Application of EOF/PCA-based methods in the post-processing of GRACE derived water variations

NASA Astrophysics Data System (ADS)

Forootan, Ehsan; Kusche, Jürgen

2010-05-01

Two problems that users of monthly GRACE gravity field solutions face are 1) the presence of correlated noise in the Stokes coefficients that increases with harmonic degree and causes ‘striping', and 2) the fact that different physical signals are overlaid and difficult to separate from each other in the data. These problems are termed the signal-noise separation problem and the signal-signal separation problem. Methods that are based on principal component analysis and empirical orthogonal functions (PCA/EOF) have been frequently proposed to deal with these problems for GRACE. However, different strategies have been applied to different (spatial: global/regional, spectral: global/order-wise, geoid/equivalent water height) representations of the GRACE level 2 data products, leading to differing results and a general feeling that PCA/EOF-based methods are to be applied ‘with care'. In addition, it is known that conventional EOF/PCA methods force separated modes to be orthogonal, and that, on the other hand, to either EOFs or PCs an arbitrary orthogonal rotation can be applied. The aim of this paper is to provide a common theoretical framework and to study the application of PCA/EOF-based methods as a signal separation tool due to post-process GRACE data products. In order to investigate and illustrate the applicability of PCA/EOF-based methods, we have employed them on GRACE level 2 monthly solutions based on the Center for Space Research, University of Texas (CSR/UT) RL04 products and on the ITG-GRACE03 solutions from the University of Bonn, and on various representations of them. Our results show that EOF modes do reveal the dominating annual, semiannual and also long-periodic signals in the global water storage variations, but they also show how choosing different strategies changes the outcome and may lead to unexpected results.

Exploring the Linkage of Sea Surface Temperature Variability on Three Spatial Scales

NASA Astrophysics Data System (ADS)

Luo, L.; Capone, D. G.; Hutchins, D.; Kiefer, D.

2011-12-01

As part of a project examining climate change in the Southern California Bight at the University of Southern California, we studied the linkage of the variability of sea surface temperature across three nested spatial scales, the north Pacific Basin, the West Coast of North American, and the Southern California Bight. Specifically, we analyzed daily GHRSST images between September 1981 and July 2009. In order to remove seasonal changes in temperature and focus upon differences between years, we calculate weekly mean temperature for each pixel from the time series, and then subjected the anomalies for the 3 spatial scales to empirical orthogonal function (EOF) analysis. The corresponding temporal expansion coefficients and spatial components (eigenvector) for each EOF mode were then generated to examine the temporal and spatial patterns of SST change. The results showed that the El Nino Southern Oscillation (ENSO) has a clear influence on the SST variability across all the three spatial scales, especially the 1st EOF mode which represents the largest variance. The comparison between the time coefficients of the 1st EOF mode and the Oceanic Nino Index (ONI) suggested that the EOF mode 1 of the Pacific Basin region matched well with almost all the El Nino and La Nina signals while the West Coast of North American captured only the strong signals and the Southern California Bight captures still fewer of the signals. This clearly indicated that the Southern California Bight is relatively insensitive to ENSO signal relative to other locations along the West Coast. The 1st EOF Mode for the West Coast of North American was also clearly influenced by upwelling. The cross correlation coefficient between each pair of the EOF mode 1 temporal expansion coefficients for the three spatial scales suggested that they were significantly correlated to each other. The effect of the Pacific Decadal Oscillation (PDO) on the SST change was also demonstrated by the temporal variability of the temporal expansion coefficients of the 2nd EOF mode. However, the correlations of 2nd EOF mode time coefficients between the three scales appeared relatively low compared the 1st EOF mode. In summary sea surface temperature in the Southern California Bight behaves like a node that is relatively insensitive to ENSO, PDO, and upwelling signals.

Factors controlling the interannual variation of 30-60-day boreal summer intraseasonal oscillation over the Asian summer monsoon region

NASA Astrophysics Data System (ADS)

Li, Jianying; Mao, Jiangyu

2018-04-01

The 30-60-day boreal summer intraseasonal oscillation (BSISO) is a dominant variability of the Asian summer monsoon (ASM), with its intensity being quantified by intraseasonal standard deviations based on OLR data. The spatial and interannual variations of the BSISO intensity are identified via empirical orthogonal function (EOF) analysis for the period 1981-2014. The first EOF mode (EOF1) shows a spatially coherent enhancement or suppression of BSISO activity over the entire ASM region, and the interannual variability of this mode is related to the sea surface temperature anomaly (SSTA) contrast between the central-eastern North Pacific (CNP) and tropical Indian Ocean. In contrast, the second mode (EOF2) exhibits a seesaw pattern between the southeastern equatorial Indian Ocean (EIO) and equatorial western Pacific (EWP), with the interannual fluctuation linked with developing ENSO events. During strong years of EOF1 mode, the enhanced low-level westerlies induced by the summer-mean SSTA contrast between the warmer CNP and cooler tropical Indian Ocean tend to form a wetter moisture background over the eastern EIO, which interacts with intraseasonal low-level convergent flows, leading to stronger equatorial eastward propagation. The intensified easterly shear favors stronger northward propagation over the South Asian and Eastern Asian/Western North Pacific sectors, respectively. Opposite situation is for weak years. For interannual variations of EOF2 mode, the seesaw patterns with enhanced BSISO activity over the southeastern EIO while weakened activity over the EWP mostly occur in the La Niña developing summers, but inverse patterns appear in the El Niño developing summers.

Ameliorating effects of ethyl acetate fraction from onion (Allium cepa L.) flesh and peel in mice following trimethyltin-induced learning and memory impairment.

PubMed

Park, Seon Kyeong; Jin, Dong Eun; Park, Chang Hyeon; Seung, Tae Wan; Guo, Tian Jiao; Song, Jong Wook; Kim, Jong Hwan; Kim, Dae Ok; Heo, Ho Jin

2015-09-01

The anti-amnesic effects of onion (Allium cepa L.) flesh (OF) 1 and peel (OP) 2 on trimethyltin (TMT) 3 -induced learning and memory dysfunction were investigated to confirm learning and memory function. The inhibitory effect against cellular acetylcholinesterase (AChE) 4 showed that the EtOAc fraction of OP (EOP 5 , IC 50 value=37.11μg/mL) was higher than the EtOAc fraction of OF (EOF 6 , IC 50 value=433.34μg/mL). The cognitive effects in ICR mice were also evaluated using Y-maze, passive avoidance, and Morris water maze tests. After the behavioral tests, AChE activity (control=100%, TMT=128%, EOF 20=108%, EOP 10=104%, and EOP 20=98%), superoxide dismutase (SOD) 7 activity, oxidized glutathione (GSSG) 8 /total glutathione (GSH) 9 and malondialdehyde (MDA) 10 production were examined. These results indicate that both EOF and EOP improved learning and memory function. The main compounds of the EOF and EOP were analyzed by Q-TOF UPLC/MS, and the results were as follows: The EOF (quercetin and quercetin-4'-glucoside) and the EOP (quercetin-4'-glucoside and isorhamnetin-4'-glucoside). Consequently, our results suggest that both EOF and EOP could be efficacious in improving cognitive function through AChE inhibition and antioxidant activity in mice brains. Copyright © 2015 Elsevier Ltd. All rights reserved.

Empirical orthogonal function analysis of cloud-containing coastal zone color scanner images of northeastern North American coastal waters

NASA Technical Reports Server (NTRS)

Eslinger, David L.; O'Brien, James J.; Iverson, Richard L.

1989-01-01

Empirical-orthogonal-function (EOF) analyses were carried out on 36 images of the Mid-Atlantic Bight and the Gulf of Maine, obtained by the CZCS aboard Nimbus 7 for the time period from February 28 through July 9, 1979, with the purpose of determining pigment concentrations in coastal waters. The EOF procedure was modified so as to include images with significant portions of data missing due to cloud obstruction, making it possible to estimate pigment values in areas beneath clouds. The results of image analyses explained observed variances in pigment concentrations and showed a south-to-north pattern corresponding to an April Mid-Atlantic Bight bloom and a June bloom over Nantucket Shoals and Platts Bank.

An Improved DINEOF Algorithm for Filling Missing Values in Spatio-Temporal Sea Surface Temperature Data.

PubMed

Ping, Bo; Su, Fenzhen; Meng, Yunshan

2016-01-01

In this study, an improved Data INterpolating Empirical Orthogonal Functions (DINEOF) algorithm for determination of missing values in a spatio-temporal dataset is presented. Compared with the ordinary DINEOF algorithm, the iterative reconstruction procedure until convergence based on every fixed EOF to determine the optimal EOF mode is not necessary and the convergence criterion is only reached once in the improved DINEOF algorithm. Moreover, in the ordinary DINEOF algorithm, after optimal EOF mode determination, the initial matrix with missing data will be iteratively reconstructed based on the optimal EOF mode until the reconstruction is convergent. However, the optimal EOF mode may be not the best EOF for some reconstructed matrices generated in the intermediate steps. Hence, instead of using asingle EOF to fill in the missing data, in the improved algorithm, the optimal EOFs for reconstruction are variable (because the optimal EOFs are variable, the improved algorithm is called VE-DINEOF algorithm in this study). To validate the accuracy of the VE-DINEOF algorithm, a sea surface temperature (SST) data set is reconstructed by using the DINEOF, I-DINEOF (proposed in 2015) and VE-DINEOF algorithms. Four parameters (Pearson correlation coefficient, signal-to-noise ratio, root-mean-square error, and mean absolute difference) are used as a measure of reconstructed accuracy. Compared with the DINEOF and I-DINEOF algorithms, the VE-DINEOF algorithm can significantly enhance the accuracy of reconstruction and shorten the computational time.

Reduced rank models for travel time estimation of low order mode pulses.

PubMed

Chandrayadula, Tarun K; Wage, Kathleen E; Worcester, Peter F; Dzieciuch, Matthew A; Mercer, James A; Andrew, Rex K; Howe, Bruce M

2013-10-01

Mode travel time estimation in the presence of internal waves (IWs) is a challenging problem. IWs perturb the sound speed, which results in travel time wander and mode scattering. A standard approach to travel time estimation is to pulse compress the broadband signal, pick the peak of the compressed time series, and average the peak time over multiple receptions to reduce variance. The peak-picking approach implicitly assumes there is a single strong arrival and does not perform well when there are multiple arrivals due to scattering. This article presents a statistical model for the scattered mode arrivals and uses the model to design improved travel time estimators. The model is based on an Empirical Orthogonal Function (EOF) analysis of the mode time series. Range-dependent simulations and data from the Long-range Ocean Acoustic Propagation Experiment (LOAPEX) indicate that the modes are represented by a small number of EOFs. The reduced-rank EOF model is used to construct a travel time estimator based on the Matched Subspace Detector (MSD). Analysis of simulation and experimental data show that the MSDs are more robust to IW scattering than peak picking. The simulation analysis also highlights how IWs affect the mode excitation by the source.

Characteristic variations of sea surface temperature with multiple time scales in the North Pacific

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanimoto, Youichi; Hanawa, Kimio; Toba, Yoshiaki

1993-06-01

It is unclear whether the recent increases in global temperatures are really due to the increase of greenhouse gases or are a manifestation of natural variability. Temporal evolution and spectral structure of sea surface temperature (SST) anomalies in the North Pacific over the last 37 years are investigated on the three characteristic time scales: shorter than 24 months (HF), 24-60 months (ES), and longer than 60 months (DC). The leading empirical-orthogonal function (EOF) for the DC time scale is characterized by a zonally elongated monopole centered at around 40[degrees]N, 180[degrees]. The leading EOF for the HF time scale is somewhatmore » similar to that for the DC time scale, although there are two centers of action with the same polarity at the mid and western Pacific. The leading EOF for the ES time scale, however, exhibits a different pattern whose center of action at the mid Pacific is located farther southeastward. In the time evolution of the SST anomalies associated with the leading EOF of the DC time scale, several anomaly periods can be identified that last five years or longer. The transition from a persistent period to another with the opposite polarity is generally very brief, except for the one that lasts throughout the late 1960s. The EOF analysis was repeated separately on these persistent anomaly periods and the long transition period. The spatial structure of the leading EOF of the SST variability with the ES time scale is found to be sensitive to the polarity of the decadal anomaly. These results are suggestive of the possible influence of the decadal SST variability upon the spatial structure of the variability with shorter time scales. 31 refs., 8 figs.« less

Electrophoretic separations in poly(dimethylsiloxane) microchips using a mixture of ionic and zwitterionic surfactants

PubMed Central

Guan, Qian; Noblitt, Scott D.; Henry, Charles S.

2012-01-01

The use of mixtures of ionic and zwitterionic surfactants in poly(dimethylsiloxane) (PDMS) microchips is reported. The effect of surfactant concentration on EOF was studied for a single anionic surfactant (sodium dodecyl sulfate, SDS), a single zwitterionic surfactant (N-tetradecylammonium-N,N-dimethyl-3-ammonio-1-propanesulfonate, TDAPS), and a mixed SDS/TDAPS surfactant system. SDS increased the EOF as reported previously while TDAPS showed an initial increase in EOF followed by a reduction at higher concentrations. When TDAPS was added to a solution containing SDS, the EOF decreased in a concentration dependent manner. The EOF for all three surfactant systems followed expected pH trends, with increasing EOF at higher pH. The mixed surfactant system allowed tuning of the EOF across a range of pH and concentration conditions. After establishing the EOF behavior, the adsorption/desorption kinetics were measured and showed a slower adsorption/desorption rate for TDAPS than SDS. Finally, the separation and electrochemical detection of model catecholamines in buffer and reduced glutathione (GSH) in red blood cell lysate using the mixed surfactant system were explored. The mixed surfactant system provided shorter analysis times and/or improved resolution when compared to the single surfactant systems. PMID:22222982

Use of Multi-class Empirical Orthogonal Function for Identification of Hydrogeological Parameters and Spatiotemporal Pattern of Multiple Recharges in Groundwater Modeling

NASA Astrophysics Data System (ADS)

Huang, C. L.; Hsu, N. S.; Yeh, W. W. G.; Hsieh, I. H.

2017-12-01

This study develops an innovative calibration method for regional groundwater modeling by using multi-class empirical orthogonal functions (EOFs). The developed method is an iterative approach. Prior to carrying out the iterative procedures, the groundwater storage hydrographs associated with the observation wells are calculated. The combined multi-class EOF amplitudes and EOF expansion coefficients of the storage hydrographs are then used to compute the initial gauss of the temporal and spatial pattern of multiple recharges. The initial guess of the hydrogeological parameters are also assigned according to in-situ pumping experiment. The recharges include net rainfall recharge and boundary recharge, and the hydrogeological parameters are riverbed leakage conductivity, horizontal hydraulic conductivity, vertical hydraulic conductivity, storage coefficient, and specific yield. The first step of the iterative algorithm is to conduct the numerical model (i.e. MODFLOW) by the initial guess / adjusted values of the recharges and parameters. Second, in order to determine the best EOF combination of the error storage hydrographs for determining the correction vectors, the objective function is devised as minimizing the root mean square error (RMSE) of the simulated storage hydrographs. The error storage hydrograph are the differences between the storage hydrographs computed from observed and simulated groundwater level fluctuations. Third, adjust the values of recharges and parameters and repeat the iterative procedures until the stopping criterion is reached. The established methodology was applied to the groundwater system of Ming-Chu Basin, Taiwan. The study period is from January 1st to December 2ed in 2012. Results showed that the optimal EOF combination for the multiple recharges and hydrogeological parameters can decrease the RMSE of the simulated storage hydrographs dramatically within three calibration iterations. It represents that the iterative approach that using EOF techniques can capture the groundwater flow tendency and detects the correction vector of the simulated error sources. Hence, the established EOF-based methodology can effectively and accurately identify the multiple recharges and hydrogeological parameters.

Empirical Orthogonal Function (EOF) Analysis of Storm-Time GPS Total Electron Content Variations

NASA Astrophysics Data System (ADS)

Thomas, E. G.; Coster, A. J.; Zhang, S.; McGranaghan, R. M.; Shepherd, S. G.; Baker, J. B.; Ruohoniemi, J. M.

2016-12-01

Large perturbations in ionospheric density are known to occur during geomagnetic storms triggered by dynamic structures in the solar wind. These ionospheric storm effects have long attracted interest due to their impact on the propagation characteristics of radio wave communications. Over the last two decades, maps of vertically-integrated total electron content (TEC) based on data collected by worldwide networks of Global Positioning System (GPS) receivers have dramatically improved our ability to monitor the spatiotemporal dynamics of prominent storm-time features such as polar cap patches and storm enhanced density (SED) plumes. In this study, we use an empirical orthogonal function (EOF) decomposition technique to identify the primary modes of spatial and temporal variability in the storm-time GPS TEC response at midlatitudes over North America during more than 100 moderate geomagnetic storms from 2001-2013. We next examine the resulting time-varying principal components and their correlation with various geophysical indices and parameters in order to derive an analytical representation. Finally, we use a truncated reconstruction of the EOF basis functions and parameterization of the principal components to produce an empirical representation of the geomagnetic storm-time response of GPS TEC for all magnetic local times local times and seasons at midlatitudes in the North American sector.

Cluster analysis of multiple planetary flow regimes

NASA Technical Reports Server (NTRS)

Mo, Kingtse; Ghil, Michael

1988-01-01

A modified cluster analysis method developed for the classification of quasi-stationary events into a few planetary flow regimes and for the examination of transitions between these regimes is described. The method was applied first to a simple deterministic model and then to a 500-mbar data set for Northern Hemisphere (NH), for which cluster analysis was carried out in the subspace of the first seven empirical orthogonal functions (EOFs). Stationary clusters were found in the low-frequency band of more than 10 days, while transient clusters were found in the band-pass frequency window between 2.5 and 6 days. In the low-frequency band, three pairs of clusters determined EOFs 1, 2, and 3, respectively; they exhibited well-known regional features, such as blocking, the Pacific/North American pattern, and wave trains. Both model and low-pass data exhibited strong bimodality.

Soil water content evaluation considering time-invariant spatial pattern and space-variant temporal change

NASA Astrophysics Data System (ADS)

Hu, W.; Si, B. C.

2013-10-01

Soil water content (SWC) varies in space and time. The objective of this study was to evaluate soil water content distribution using a statistical model. The model divides spatial SWC series into time-invariant spatial patterns, space-invariant temporal changes, and space- and time-dependent redistribution terms. The redistribution term is responsible for the temporal changes in spatial patterns of SWC. An empirical orthogonal function was used to separate the total variations of redistribution terms into the sum of the product of spatial structures (EOFs) and temporally-varying coefficients (ECs). Model performance was evaluated using SWC data of near-surface (0-0.2 m) and root-zone (0-1.0 m) from a Canadian Prairie landscape. Three significant EOFs were identified for redistribution term for both soil layers. EOF1 dominated the variations of redistribution terms and it resulted in more changes (recharge or discharge) in SWC at wetter locations. Depth to CaCO3 layer and organic carbon were the two most important controlling factors of EOF1, and together, they explained over 80% of the variations in EOF1. Weak correlation existed between either EOF2 or EOF3 and the observed factors. A reasonable prediction of SWC distribution was obtained with this model using cross validation. The model performed better in the root zone than in the near surface, and it outperformed conventional EOF method in case soil moisture deviated from the average conditions.

Spatio-temporal patterns of soil water storage under dryland agriculture at the watershed scale

NASA Astrophysics Data System (ADS)

Ibrahim, Hesham M.; Huggins, David R.

2011-07-01

SummarySpatio-temporal patterns of soil water are major determinants of crop yield potential in dryland agriculture and can serve as the basis for delineating precision management zones. Soil water patterns can vary significantly due to differences in seasonal precipitation, soil properties and topographic features. In this study we used empirical orthogonal function (EOF) analysis to characterize the spatial variability of soil water at the Washington State University Cook Agronomy Farm (CAF) near Pullman, WA. During the period 1999-2006, the CAF was divided into three roughly equal blocks (A, B, and C), and soil water at 0.3 m intervals to a depth of 1.5 m measured gravimetrically at approximately one third of the 369 geo-referenced points on the 37-ha watershed. These data were combined with terrain attributes, soil bulk density and apparent soil conductivity (EC a). The first EOF generated from the three blocks explained 73-76% of the soil water variability. Field patterns of soil water based on EOF interpolation varied between wet and dry conditions during spring and fall seasons. Under wet conditions, elevation and wetness index were the dominant factors regulating the spatial patterns of soil water. As soil dries out during summer and fall, soil properties (EC a and bulk density) become more important in explaining the spatial patterns of soil water. The EOFs generated from block B, which represents average topographic and soil properties, provided better estimates of soil water over the entire watershed with larger Nash-Sutcliffe Coefficient of Efficiency (NSCE) values, especially when the first two EOFs were retained. Including more than the first two EOFs did not significantly increase the NSCE of soil water estimate. The EOF interpolation method to estimate soil water variability worked slightly better during spring than during fall, with average NSCE values of 0.23 and 0.20, respectively. The predictable patterns of stored soil water in the spring could serve as the basis for delineating precision management zones as yield potential is largely driven by water availability. The EOF-based method has the advantage of estimating the soil water variability based on soil water data from several measurement times, whereas in regression methods only soil water measurement at a single time are used. The EOF-based method can also be used to estimate soil water at any time other than measurement times, assuming the average soil water of the watershed is known at that time.

Decadal period external magnetic field variations determined via eigenanalysis

NASA Astrophysics Data System (ADS)

Shore, R. M.; Whaler, K. A.; Macmillan, S.; Beggan, C.; Velímský, J.; Olsen, N.

2016-06-01

We perform a reanalysis of hourly mean magnetic data from ground-based observatories spanning 1997-2009 inclusive, in order to isolate (after removal of core and crustal field estimates) the spatiotemporal morphology of the external fields important to mantle induction, on (long) periods of months to a full solar cycle. Our analysis focuses on geomagnetically quiet days and middle to low latitudes. We use the climatological eigenanalysis technique called empirical orthogonal functions (EOFs), which allows us to identify discrete spatiotemporal patterns with no a priori specification of their geometry -- the form of the decomposition is controlled by the data. We apply a spherical harmonic analysis to the EOF outputs in a joint inversion for internal and external coefficients. The results justify our assumption that the EOF procedure responds primarily to the long-period external inducing field contributions. Though we cannot determine uniquely the contributory source regions of these inducing fields, we find that they have distinct temporal characteristics which enable some inference of sources. An identified annual-period pattern appears to stem from a north-south seasonal motion of the background mean external field distribution. Separate patterns of semiannual and solar-cycle-length periods appear to stem from the amplitude modulations of spatially fixed background fields.

Conditioned empirical orthogonal functions for interpolation of runoff time series along rivers: Application to reconstruction of missing monthly records

NASA Astrophysics Data System (ADS)

Li, Lingqi; Gottschalk, Lars; Krasovskaia, Irina; Xiong, Lihua

2018-01-01

Reconstruction of missing runoff data is of important significance to solve contradictions between the common situation of gaps and the fundamental necessity of complete time series for reliable hydrological research. The conventional empirical orthogonal functions (EOF) approach has been documented to be useful for interpolating hydrological series based upon spatiotemporal decomposition of runoff variation patterns, without additional measurements (e.g., precipitation, land cover). This study develops a new EOF-based approach (abbreviated as CEOF) that conditions EOF expansion on the oscillations at outlet (or any other reference station) of a target basin and creates a set of residual series by removing the dependence on this reference series, in order to redefine the amplitude functions (components). This development allows a transparent hydrological interpretation of the dimensionless components and thereby strengthens their capacities to explain various runoff regimes in a basin. The two approaches are demonstrated on an application of discharge observations from the Ganjiang basin, China. Two alternatives for determining amplitude functions based on centred and standardised series, respectively, are tested. The convergence in the reconstruction of observations at different sites as a function of the number of components and its relation to the characteristics of the site are analysed. Results indicate that the CEOF approach offers an efficient way to restore runoff records with only one to four components; it shows more superiority in nested large basins than at headwater sites and often performs better than the EOF approach when using standardised series, especially in improving infilling accuracy for low flows. Comparisons against other interpolation methods (i.e., nearest neighbour, linear regression, inverse distance weighting) further confirm the advantage of the EOF-based approaches in avoiding spatial and temporal inconsistencies in estimated series.

Multi-year Droughts in California in the Last Two Decades

NASA Astrophysics Data System (ADS)

Myoung, B.; Kafatos, M.

2016-12-01

Multi-year droughts in California including the notorious 2013-2014 drought became serious problems recently, causing significant socio-economic damages. In the present study, focusing on the three multi-year droughts in California, i.e., 1999-2002, 2007-2009, and 2012-2014, during the recent two decades (1995-2014), we compared and investigated their characteristics of the atmosphere and the oceans. By positioning abnormally strong anticyclonic circulations at 500 hPa over the North Pacific, the droughts seem to start around strong La Niña years and continued or intensified until the year prior to an El Niño. While precipitation decreases in La Niña years have been well documented previously, the intensification of droughts in the later period has not. The Empirical Orthogonal Function (EOF) and correlation analyses suggest that, around strong La Niña years, the first EOF mode (EOF1) of the 500 hPa height is active, while the second EOF mode (EOF2) becomes active in moderate/weak La Nina years. It is also found that while EOF1 is sensitive to SST variability in the central Pacific which is associated with the major ENSO events, EOF2 is sensitive to that in the western/South Pacific. Relations to various climate variability other than ENSO, e.g., Pacific Decadal Oscillation (PDO), Tropical/Northern Hemisphere (TNH), Pacific/North American (PNA), and North Atlantic Oscillation (NAO), are also examined.

Analysis and Modeling of the Arctic Oscillation Using a Simple Barotropic Model with Baroclinic Eddy Forcing.

NASA Astrophysics Data System (ADS)

Tanaka, H. L.

2003-06-01

In this study, a numerical simulation of the Arctic Oscillation (AO) is conducted using a simple barotropic model that considers the barotropic-baroclinic interactions as the external forcing. The model is referred to as a barotropic S model since the external forcing is obtained statistically from the long-term historical data, solving an inverse problem. The barotropic S model has been integrated for 51 years under a perpetual January condition and the dominant empirical orthogonal function (EOF) modes in the model have been analyzed. The results are compared with the EOF analysis of the barotropic component of the real atmosphere based on the daily NCEP-NCAR reanalysis for 50 yr from 1950 to 1999.According to the result, the first EOF of the model atmosphere appears to be the AO similar to the observation. The annular structure of the AO and the two centers of action at Pacific and Atlantic are simulated nicely by the barotropic S model. Therefore, the atmospheric low-frequency variabilities have been captured satisfactorily even by the simple barotropic model.The EOF analysis is further conducted to the external forcing of the barotropic S model. The structure of the dominant forcing shows the characteristics of synoptic-scale disturbances of zonal wavenumber 6 along the Pacific storm track. The forcing is induced by the barotropic-baroclinic interactions associated with baroclinic instability.The result suggests that the AO can be understood as the natural variability of the barotropic component of the atmosphere induced by the inherent barotropic dynamics, which is forced by the barotropic-baroclinic interactions. The fluctuating upscale energy cascade from planetary waves and synoptic disturbances to the zonal motion plays the key role for the excitation of the AO.

Analysis of satellite precipitation over East Africa during last decades

NASA Astrophysics Data System (ADS)

Cattani, Elsa; Wenhaji Ndomeni, Claudine; Merino, Andrés; Levizzani, Vincenzo

2016-04-01

Daily accumulated precipitation time series from satellite retrieval algorithms (e.g., ARC2 and TAMSAT) are exploited to extract the spatial and temporal variability of East Africa (EA - 5°S-20°N, 28°E-52°E) precipitation during last decades (1983-2013). The Empirical Orthogonal Function (EOF) analysis is applied to precipitation time series to investigate the spatial and temporal variability in particular for October-November-December referred to as the short rain season. Moreover, the connection among EA's precipitation, sea surface temperature, and soil moisture is analyzed through the correlation with the dominant EOF modes of variability. Preliminary results concern the first two EOF's modes for the ARC2 data set. EOF1 is characterized by an inter-annual variability and a positive correlation between precipitation and El Niño, positive Indian Ocean Dipole mode, and soil moisture, while EOF2 shows a dipole structure of spatial variability associated with a longer scale temporal variability. This second dominant mode is mostly linked to sea surface temperature variations in the North Atlantic Ocean. Further analyses are carried out by computing the time series of the joint CCI/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI, http://etccdi.pacificclimate.org/index.shtml), i.e. RX1day, RX5day, CDD, CDD, CWD, SDII, PRCPTOT, R10, R20. The purpose is to identify the occurrenes of extreme events (droughts and floods) and extract precipitation temporal variation by trend analysis (Mann-Kendall technique). Results for the ARC2 data set demonstrate the existence of a dipole spatial pattern in the linear trend of the time series of PRCPTOT (annual precipitation considering days with a rain rate > 1 mm) and SDII (average precipitation on wet days over a year). A negative trend is mainly present over West Ethiopia and Sudan, whereas a positive trend is exhibited over East Ethiopia and Somalia. CDD (maximum number of consecutive dry days) and CWD (maximum number of consecutive wet days) time series do not exhibit a similar behavior and trends are generally weaker with a lower significance level with respect to PRCPTOT and SDII.

An Investigation of Dust Storms Observed with the Mars Color Imager

NASA Technical Reports Server (NTRS)

Guzewich, Scott D.; Toigo, Anthony D.; Wang, Huiqun

2017-01-01

Daily global imaging by the Mars Color Imager (MARCI) continues the record of the Mars Orbiter Camera (MOC) and has allowed creation of a long-duration record of Martian dust storms. We observe dust storms over the first two Mars years of the MARCI record, including tracking individual storms over multiple sols, as well as tracking the growth and recession of the seasonal polar caps. Using the combined 6 Mars year record of textured dust storms (storms with visible textures on the observed dust cloud tops), we study the relationship between textured dust storm activity and meteorology (as simulated by the MarsWRF general circulation model) and surface properties. We find that textured dust storms preferentially occur in places and seasons with above average surface wind stress. Textured dust storm occurrence also has a modest linear anti-correlation with surface albedo (0.43) and topography (0.40). Lastly, we perform an empirical orthogonal function (EOF) analysis on the distribution of occurrence of textured dust storms and find that over 50 of the variance in textured dust storm activity can be explained by two EOF modes. We associate the first EOF mode with cap-edge storms just before Ls = 180deg and the second EOF mode with flushing dust storms that occur from Ls = 180-210deg and again near Ls = 320deg.

Determination of the Navier slip coefficient of microchannels exploiting the streaming potential.

PubMed

Park, Hung Mok

2012-03-01

For most microchannels made of hydrophobic materials such as polymers, velocity slip occurs at the wall, affecting volumetric flow rate of electroosmotic flow Q(eof) and streaming potential (∂ϕ(str)/∂z). Since most techniques exploit Q(eof) or (∂ϕ(str)/∂z) to determine the zeta potential, ζ, it is very difficult to measure ζ of hydrophobic walls, if the slip coefficient b is not found a priori. Until now, Q(eof) and (∂ϕ(str)/∂z) are known to depend on ζ and b in a same functional form, which makes it impossible to estimate ζ or b separately using measurements of Q(eof) and (∂ϕ(str)/∂z). However, exploiting the analytic formula for Q(eof) and (∂ϕ(str)/∂z) derived in the present work, it is found that the effect of ζ and that of b on Q(eof) and (∂ϕ(str)/∂z) can be separated from each other by varying the bulk ionic concentration. Thus, the slip coefficient as well as the zeta potential of hydrophobic microchannels can be found with reasonable accuracy by means of a nonlinear curve fitting method using measured data of Q(eof) and (∂ϕ(str)/∂z) at various bulk ionic concentrations. The present method allows an accurate estimation of slip coefficient of hydrophobic microchannels, which is quite simple and cheap compared with methods employing microparticle velocimetry. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Climate forcing for dynamics of dissolved inorganic nutrients at Palmer Station, Antarctica: An interdecadal (1993-2013) analysis

NASA Astrophysics Data System (ADS)

Kim, Hyewon; Doney, Scott C.; Iannuzzi, Richard A.; Meredith, Michael P.; Martinson, Douglas G.; Ducklow, Hugh W.

2016-09-01

We analyzed 20 years (1993-2013) of observations of dissolved inorganic macronutrients (nitrate, N; phosphate, P; and silicate, Si) and chlorophyll a (Chl) at Palmer Station, Antarctica (64.8°S, 64.1°W) to elucidate how large-scale climate and local physical forcing affect the interannual variability in the seasonal phytoplankton bloom and associated drawdown of nutrients. The leading modes of nutrients (N, P, and Si empirical orthogonal functions 1, EOF1) represent overall negative anomalies throughout growing seasons, showing a mixed signal of variability in the initial levels and drawdown thereafter (low-frequency dynamics). The second most common seasonal patterns of nitrate and phosphate (N and P EOF2) capture prolonged drawdown events during December-March, which are correlated to Chl EOF1. Si EOF2 captures a drawdown event during November-December, which is correlated to Chl EOF2. These different drawdown patterns are shaped by different sets of physical and climate forcing mechanisms. N and P drawdown events during December-March are influenced by the winter and spring Southern Annular Mode (SAM) phase, where nutrient utilization is enhanced in a stabilized upper water column as a consequence of SAM-driven winter sea ice and spring wind dynamics. Si drawdown during November-December is influenced by early sea ice retreat, where ice breakup may induce abrupt water column stratification and a subsequent diatom bloom or release of diatom cells from within the sea ice. Our findings underscore that seasonal nutrient dynamics in the coastal WAP are coupled to large-scale climate forcing and related physics, understanding of which may enable improved projections of biogeochemical responses to climate change.

Spatio-temporal patterns of soil water storage under dryland agriculture at the watershed scale

USDA-ARS?s Scientific Manuscript database

Soil water patterns vary significantly due to precipitation, soil properties, topographic features, and land use. We used empirical orthogonal function (EOF) analysis to characterize the spatial variability of soil water across a 37-ha field of the Washington State University Cook Agronomy Farm near...

Controlling retention, selectivity and magnitude of EOF by segmented monolithic columns consisting of octadecyl and naphthyl monolithic segments--applications to RP-CEC of both neutral and charged solutes.

PubMed

Karenga, Samuel; El Rassi, Ziad

2011-04-01

Monolithic capillaries made of two adjoining segments each filled with a different monolith were introduced for the control and manipulation of the electroosmotic flow (EOF), retention and selectivity in reversed phase-capillary electrochromatography (RP-CEC). These columns were called segmented monolithic columns (SMCs) where one segment was filled with a naphthyl methacrylate monolith (NMM) to provide hydrophobic and π-interactions, while the other segment was filled with an octadecyl acrylate monolith (ODM) to provide solely hydrophobic interaction. The ODM segment not only provided hydrophobic interactions but also functioned as the EOF accelerator segment. The average EOF of the SMC increased linearly with increasing the fractional length of the ODM segment. The neutral SMC provided a convenient way for tuning EOF, selectivity and retention in the absence of annoying electrostatic interactions and irreversible solute adsorption. The SMCs allowed the separation of a wide range of neutral solutes including polycyclic aromatic hydrocarbons (PAHs) that are difficult to separate using conventional alkyl-bonded stationary phases. In all cases, the k' of a given solute was a linear function of the fractional length of the ODM or NMM segment in the SMCs, thus facilitating the tailoring of a given SMC to solve a given separation problem. At some ODM fractional length, the fabricated SMC allowed the separation of charged solutes such as peptides and proteins that could not otherwise be achieved on a monolithic column made from NMM as an isotropic stationary phase due to the lower EOF exhibited by this monolith. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards the prediction of the East Africa short rains based on sea-surface temperature-atmosphere coupling

NASA Astrophysics Data System (ADS)

Mutai, C. C.; Ward, M. N.; Colman, A. W.

1998-07-01

It is shown that the July-September sea-surface temperature (SST) pattern contains moderately strong relationships with the October-December (OND) seasonal rainfall total averaged across East Africa 15°S-5°N, 30°-41.25°E. The relations can be described by using three rotated global SST empirical orthogonal functions (EOFs), mainly measuring aspects of SST patterns in the tropical Pacific (related to El Niño/Southern Oscillation), tropical Indian and, to a lesser extent, tropical Atlantic. Confidence in the relationships is raised because the three EOFs correlate significantly with OND near-surface divergence over the tropical Pacific, Indian and Atlantic Oceans (extending into Northern mid-latitudes), as well as with the rainfall in East Africa and also with rainfall across southern and western tropical Africa.For the East African region, multiple linear regression (MLR) and linear discriminant analysis prediction models are tested. The predictors are pre-rainfall season values of the three rotated SST EOFs. The predictors use information through September. Validating MLR hindcasts using a 1945-1966 (1967-1988) training period and a 1967-1988 (1945-1966) testing period between 30 to 60% of the area-averaged rainfall variance is explained. To achieve unbiased estimates of the expected skill of a forecast system, it is safest to keep model training and testing periods completely separate. The above strategy achieves this in the most important step of ensuring that the models fit the SST predictors to the rainfall predictand using years independent of the testing period. However, the EOFs were calculated over 1901-1980, so for hindcasts prior to 1981, the EOFs describe the SST variability a little better than could be achieved in real-time, which could inflate skill estimates. Tests in the years 1981-1994, independent of the 1901-1980 eigenvector analysis period, do produce similar levels of skill, but a few more forecast years are needed to confirm this result. It is shown that the mean verification at each individual location within East Africa is somewhat lower, which is important to consider for some applications. The need to monitor the prediction relationships and update the models is emphasised. Furthermore, these forecasts only become available as the OND season is underway, though some evidence is found for one of the EOF predictors having skill as early as June.

Statistical Prediction of Sea Ice Concentration over Arctic

NASA Astrophysics Data System (ADS)

Kim, Jongho; Jeong, Jee-Hoon; Kim, Baek-Min

2017-04-01

In this study, a statistical method that predict sea ice concentration (SIC) over the Arctic is developed. We first calculate the Season-reliant Empirical Orthogonal Functions (S-EOFs) of monthly Arctic SIC from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data, which contain the seasonal cycles (12 months long) of dominant SIC anomaly patterns. Then, the current SIC state index is determined by projecting observed SIC anomalies for latest 12 months to the S-EOFs. Assuming the current SIC anomalies follow the spatio-temporal evolution in the S-EOFs, we project the future (upto 12 months) SIC anomalies by multiplying the SI and the corresponding S-EOF and then taking summation. The predictive skill is assessed by hindcast experiments initialized at all the months for 1980-2010. When comparing predictive skill of SIC predicted by statistical model and NCEP CFS v2, the statistical model shows a higher skill in predicting sea ice concentration and extent.

Assimilation of altimeter data into a quasigeostrophic ocean model using optimal interpolation and eofs

NASA Astrophysics Data System (ADS)

Rienecker, M. M.; Adamec, D.

1995-01-01

An ensemble of fraternal-twin experiments is used to assess the utility of optimal interpolation and model-based vertical empirical orthogonal functions (eofs) of streamfunction variability to assimilate satellite altimeter data into ocean models. Simulated altimeter data are assimilated into a basin-wide 3-layer quasi-geostrophic model with a horizontal grid spacing of 15 km. The effects of bottom topography are included and the model is forced by a wind stress curl distribution which is constant in time. The simulated data are extracted, along altimeter tracks with spatial and temporal characteristics of Geosat, from a reference model ocean with a slightly different climatology from that generated by the model used for assimilation. The use of vertical eofs determined from the model-generated streamfunction variability is shown to be effective in aiding the model's dynamical extrapolation of the surface information throughout the rest of the water column. After a single repeat cycle (17 days), the analysis errors are reduced markedly from the initial level, by 52% in the surface layer, 41% in the second layer and 11% in the bottom layer. The largest differences between the assimilation analysis and the reference ocean are found in the nonlinear regime of the mid-latitude jet in all layers. After 100 days of assimilation, the error in the upper two layers has been reduced by over 50% and that in the bottom layer by 38%. The essence of the method is that the eofs capture the statistics of the dynamical balances in the model and ensure that this balance is not inappropriately disturbed during the assimilation process. This statistical balance includes any potential vorticity homogeneity which may be associated with the eddy stirring by mid-latitude surface jets.

Procrustean rotation in concert with principal component analysis of molecular dynamics trajectories: Quantifying global and local differences between conformational samples.

PubMed

Oblinsky, Daniel G; Vanschouwen, Bryan M B; Gordon, Heather L; Rothstein, Stuart M

2009-12-14

Given the principal component analysis (PCA) of a molecular dynamics (MD) conformational trajectory for a model protein, we perform orthogonal Procrustean rotation to "best fit" the PCA squared-loading matrix to that of a target matrix computed for a related but different molecular system. The sum of squared deviations of the elements of the rotated matrix from those of the target, known as the error of fit (EOF), provides a quantitative measure of the dissimilarity between the two conformational samples. To estimate precision of the EOF, we perform bootstrap resampling of the molecular conformations within the trajectories, generating a distribution of EOF values for the system and target. The average EOF per variable is determined and visualized to ascertain where, locally, system and target sample properties differ. We illustrate this approach by analyzing MD trajectories for the wild-type and four selected mutants of the beta1 domain of protein G.

Procrustean rotation in concert with principal component analysis of molecular dynamics trajectories: Quantifying global and local differences between conformational samples

NASA Astrophysics Data System (ADS)

Oblinsky, Daniel G.; VanSchouwen, Bryan M. B.; Gordon, Heather L.; Rothstein, Stuart M.

2009-12-01

Given the principal component analysis (PCA) of a molecular dynamics (MD) conformational trajectory for a model protein, we perform orthogonal Procrustean rotation to "best fit" the PCA squared-loading matrix to that of a target matrix computed for a related but different molecular system. The sum of squared deviations of the elements of the rotated matrix from those of the target, known as the error of fit (EOF), provides a quantitative measure of the dissimilarity between the two conformational samples. To estimate precision of the EOF, we perform bootstrap resampling of the molecular conformations within the trajectories, generating a distribution of EOF values for the system and target. The average EOF per variable is determined and visualized to ascertain where, locally, system and target sample properties differ. We illustrate this approach by analyzing MD trajectories for the wild-type and four selected mutants of the β1 domain of protein G.

Photochemical properties and sensor applications of modified yellow fluorescent protein (YFP) covalently attached to the surfaces of etched optical fibers (EOFs).

PubMed

Veselov, Alexey A; Abraham, Bobin George; Lemmetyinen, Helge; Karp, Matti T; Tkachenko, Nikolai V

2012-01-01

Fluorescent proteins have the inherent ability to act as sensing components which function both in vitro and inside living cells. We describe here a novel study on a covalent site-specific bonding of fluorescent proteins to form self-assembled monolayers (SAMs) on the surface of etched optical fibers (EOFs). Deposition of fluorescent proteins on EOFs gives the opportunity to increase the interaction of guided light with deposited molecules relative to plane glass surfaces. The EOF modification is carried out by surface activation using 3-aminopropylthrimethoxysilane (APTMS) and bifunctional crosslinker sulfosuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (sulfo-SMCC) which exposes sulfhydryl-reactive maleimide groups followed by covalent site-specific coupling of modified yellow fluorescent protein (YFP). Steady-state and fluorescence lifetime measurements confirm the formation of SAM. The sensor applications of YPF SAMs on EOF are demonstrated by the gradual increase of emission intensity upon addition of Ca(2+) ions in the concentration range from a few tens of micromolars up to a few tens of millimolars. The studies on the effect of pH, divalent cations, denaturing agents, and proteases reveal the stability of YFP on EOFs at normal physiological conditions. However, treatments with 0.5% SDS at pH 8.5 and protease trypsin are found to denaturate or cleave the YFP from fiber surfaces.

Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP

NASA Astrophysics Data System (ADS)

Liu, Zhao-Jun; Nakamura, Hirohiko; Zhu, Xiao-Hua; Nishina, Ayako; Dong, Menghong

2017-09-01

Ferryboat Acoustic Doppler Current Profiler (ADCP) data from 2003 to 2012 are used to estimate the tidal and residual currents across the northern Ryukyu Island chain (RIC) between the islands of Okinawa and Amamioshima. In this region, the M2 tide current is the strongest tidal component, and the K1 tide current is the strongest diurnal tidal component. The corresponding maximum amplitudes are 40 and 34 cm s-1, respectively. After removal of the tidal currents, the mean volume transport, 1.5 ± 2.7 Sv, flows into the East China Sea (ECS) from the western North Pacific through four channels in this area. In an empirical orthogonal function (EOF) analysis performed to clarify the temporal and spatial variability of currents through the four channels, the first two EOF modes account for 71% and 18% of the total variance, respectively. The EOF1 mode shows a clear bottom-intensified mode through the deep channel, which is likely to be formed by the propagation of bottom-trapped long topographic Rossby wave caused by the impingement of westward-propagating mesoscale eddies upon the eastern slope of the northern RIC. The EOF2 mode has significant seasonal variability and may be driven by the wind stress prevailing over the Kuroshio flow region around the northern RIC in October-November. This study provides observational evidence of the water exchanges across the northern RIC, which is essential for constructing a circulation scheme in the North Pacific subtropical western boundary region.

Impacts of Pacific SSTs on California Winter Precipitation

NASA Astrophysics Data System (ADS)

Myoung, B.; Kafatos, M.

2017-12-01

Consecutive below-normal precipitation years and resulted multi-year droughts are critical issues as the recent 2012-2015 drought of California caused tremendous socio-economic damages. However, studies on the causes of the multi-year droughts lack. In this study, focusing on the three multi-year droughts (1999-2002, 2007-2009, and 2012-2015) in California during the last two decades, we investigated the atmospheric and oceanic characteristics of the three drought events for winter (December-February, DJF) in order to understand large-scale circulations that are responsible for initiation, maintenance, and termination of the droughts. It was found that abnormally developed upper-tropospheric ridges over the North Pacific are primarily responsible for precipitation deficits and then droughts. These ridges developed when negative sea surface temperature anomalies (SSTs) including La Niña events are pervasive in the tropical Pacific. After 3 or 4 years, the droughts ended under the opposite conditions; upper-tropospheric troughs in the North Pacific with El Niño events in the tropics. Results of Empirical Orthogonal Function (EOF) analysis for the 41-year (1974/75-2014/15) 500 hPa geopotential height in DJF revealed that, during the drought periods, the positive phases of the first and second EOF mode (EOF1+ and EOF2+, respectively) were active one by one, positioning upper-tropospheric ridges over the North Pacific. While EOF1+ is associated with cold tropical central Pacific and negative Pacific Decadal Oscillation (PDO), EOF2+ is associated with the tropical east-west SST dipole pattern (i.e., warm western tropical Pacific and cool eastern tropical Pacific near the southern Peru). Based on these results, we developed a regression model for winter precipitation. While dominant SST factors differ by decades, for the recent two decades (1994/1995-2014/2015), 56% variability of DJF precipitation is explained by the tropical east-west SST dipole pattern and PDO (NINO3.4 signal removed) together. These results suggest that SST variability not only in the western/eastern tropical Pacific but also in the North Pacific independently contribute to precipitation variability and long-term droughts in California.

Models of electroosmotic flow in micro- and nanochannels

NASA Astrophysics Data System (ADS)

Zheng, Z.; Conlisk, A. T.; Sadr, R.; Yoda, M.

2003-11-01

Understanding electrooosmotic flow (EOF) is essential for developing efficient drug delivery and rapid biomolecular analysis devices given the extremely high pressure gradients required to drive flows through channels smaller than about 10 μ m. We consider fully-developed and steady EOF in one- and two-dimensional micro- and nanochannel geometries. The fluid, which is assumed to behave as a continuum, is a mixture of a neutral solvent such as water and a salt where the ionic species are entirely dissociated. The model can be used to analyze EOF where the opposite channel walls are oppositely charged and EOF with arbitrary electric double layer thickness. Unlike most previous models which assume a wall ζ -potential a priori, the model calculates the boundary conditions for the (wall) mole fractions using the equilibrium electrochemical potential in the upstream reservoir. We can therefore predict the wall ζ -potential, and calculate EOF with spatially and temporally varying wall ζ -potentials. The model results for electroosmotic mobility and volumetric flow rate are compared with those from three independent experimental datasets, and found to be in good agreement with all three sets of experimental data for channel sizes ranging from O(10 nm) to O(10 μ m). The limits of the continuum theory for EOF are discussed.

Nordic Sea Level - Analysis of PSMSL RLR Tide Gauge data

NASA Astrophysics Data System (ADS)

Knudsen, Per; Andersen, Ole

2015-04-01

Tide gauge data from the Nordic region covering a period of time from 1920 to 2000 are evaluated. 63 stations having RLR data for at least 40 years have been used. Each tide gauge data record was averaged to annual averages after the monthly average seasonal anomalies were removed. Some stations lack data, especially before around 1950. Hence, to compute representative sea level trends for the 1920-2000 period a procedure for filling in estimated sea level values in the voids, is needed. To fill in voids in the tide gauge data records a reconstruction method was applied that utilizes EOF.s in an iterative manner. Subsequently the trends were computed. The estimated trends range from about -8 mm/year to 2 mm/year reflecting both post-glacial uplift and sea level rise. An evaluation of the first EOFs show that the first EOF clearly describes the trends in the time series. EOF #2 and #3 describe differences in the inter-annual sea level variability with-in the Baltic Sea and differences between the Baltic and the North Atlantic / Norwegian seas, respectively.

Electroosmotic flow in microchannels with nanostructures.

PubMed

Yasui, Takao; Kaji, Noritada; Mohamadi, Mohamad Reza; Okamoto, Yukihiro; Tokeshi, Manabu; Horiike, Yasuhiro; Baba, Yoshinobu

2011-10-25

Here we report that nanopillar array structures have an intrinsic ability to suppress electroosmotic flow (EOF). Currently using glass chips for electrophoresis requires laborious surface coating to control EOF, which works as a counterflow to the electrophoresis mobility of negatively charged samples such as DNA and sodium dodecyl sulfate (SDS) denatured proteins. Due to the intrinsic ability of the nanopillar array to suppress the EOF, we carried out electrophoresis of SDS-protein complexes in nanopillar chips without adding any reagent to suppress protein adsorption and the EOF. We also show that the EOF profile inside a nanopillar region was deformed to an inverse parabolic flow. We used a combination of EOF measurements and fluorescence observations to compare EOF in microchannel, nanochannel, and nanopillar array chips. Our results of EOF measurements in micro- and nanochannel chips were in complete agreement with the conventional equation of the EOF mobility (μ(EOF-channel) = αC(i)(-0.5), where C(i) is the bulk concentration of the i-ions and α differs in micro- and nanochannels), whereas EOF in the nanopillar chips did not follow this equation. Therefore we developed a new modified form of the conventional EOF equation, μ(EOF-nanopillar) ≈ β[C(i) - (C(i)(2)/N(i))], where N(i) is the number of sites available to i-ions and β differs for each nanopillar chip because of different spacings or patterns, etc. The modified equation of the EOF mobility that we proposed here was in good agreement with our experimental results. In this equation, we showed that the charge density of the nanopillar region, that is, the total number of nanopillars inside the microchannel, affected the suppression of EOF, and the arrangement of nanopillars into a tilted or square array had no effect on it.

Sea level reconstructions from altimetry and tide gauges using independent component analysis

NASA Astrophysics Data System (ADS)

Brunnabend, Sandra-Esther; Kusche, Jürgen; Forootan, Ehsan

2017-04-01

Many reconstructions of global and regional sea level rise derived from tide gauges and satellite altimetry used the method of empirical orthogonal functions (EOF) to reduce noise, improving the spatial resolution of the reconstructed outputs and investigate the different signals in climate time series. However, the second order EOF method has some limitations, e.g. in the separation of individual physical signals into different modes of sea level variations and in the capability to physically interpret the different modes as they are assumed to be orthogonal. Therefore, we investigate the use of the more advanced statistical signal decomposition technique called independent component analysis (ICA) to reconstruct global and regional sea level change from satellite altimetry and tide gauge records. Our results indicate that the used method has almost no influence on the reconstruction of global mean sea level change (1.6 mm/yr from 1960-2010 and 2.9 mm/yr from 1993-2013). Only different numbers of modes are needed for the reconstruction. Using the ICA method is advantageous for separating independent climate variability signals from regional sea level variations as the mixing problem of the EOF method is strongly reduced. As an example, the modes most dominated by the El Niño-Southern Oscillation (ENSO) signal are compared. Regional sea level changes near Tianjin, China, Los Angeles, USA, and Majuro, Marshall Islands are reconstructed and the contributions from ENSO are identified.

Signatures of large-scale and local climates on the demography of white-tailed ptarmigan in Rocky Mountain National Park, Colorado, USA.

PubMed

Wang, Guiming; Hobbs, N Thompson; Galbraith, Hector; Giesen, Kenneth M

2002-09-01

Global climate change may impact wildlife populations by affecting local weather patterns, which, in turn, can impact a variety of ecological processes. However, it is not clear that local variations in ecological processes can be explained by large-scale patterns of climate. The North Atlantic oscillation (NAO) is a large-scale climate phenomenon that has been shown to influence the population dynamics of some animals. Although effects of the NAO on vertebrate population dynamics have been studied, it remains uncertain whether it broadly predicts the impact of weather on species. We examined the ability of local weather data and the NAO to explain the annual variation in population dynamics of white-tailed ptarmigan ( Lagopus leucurus) in Rocky Mountain National Park, USA. We performed canonical correlation analysis on the demographic subspace of ptarmigan and local-climate subspace defined by the empirical orthogonal function (EOF) using data from 1975 to 1999. We found that two subspaces were significantly correlated on the first canonical variable. The Pearson correlation coefficient of the first EOF values of the demographic and local-climate subspaces was significant. The population density and the first EOF of local-climate subspace influenced the ptarmigan population with 1-year lags in the Gompertz model. However, the NAO index was neither related to the first two EOF of local-climate subspace nor to the first EOF of the demographic subspace of ptarmigan. Moreover, the NAO index was not a significant term in the Gompertz model for the ptarmigan population. Therefore, local climate had stronger signature on the demography of ptarmigan than did a large-scale index, i.e., the NAO index. We conclude that local responses of wildlife populations to changing climate may not be adequately explained by models that project large-scale climatic patterns.

Variability in Sea Surface Height: A Qualitative Measure for the Meridional Overturning in the North Atlantic

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa

1999-01-01

Sea surface height (SSH) from altimeter observations from 1992 on and from modeling results is investigated to determine the modes of variability and the linkages to the state of oceanic circulation in the North Atlantic. First the altimeter and model simulated SSH are analyzed using the empirical orthogonal function (EOF) analysis. They are found to share a similar leading mode where the center of action is along the Gulf Stream and North Atlantic Current with opposite sign anomalies in the subpolar gyre and in the slope waters along the Eastern Seaboard. The time series of the leading EOF mode from the altimeter data shows that between winters of 1995 and 1996, SSH over the Gulf Stream decreased by about 12cm which change is reproduced by the model simulation. Based on the relationship from the model simulations between the time series of the SSH EOF1 and meridional heat transport, it is suggested that associated with this SSH change in 1995-96, the overturning has slowed down from its heights in the early 90's. Furthermore, it is shown that decadal variability in the leading SSH mode originates from the thermal forcing component. This adds confidence to the qualitative relationship between the state of overturning/meridional heat transport and SSH in the limited area described by the EOF1. SSH variability in the eastern side of the North Atlantic basin, outside the western boundary current region, is determined by local and remote (Rossby waves) wind stress curl forcing.

Changes in the frequency of extreme air pollution events over the Eastern United States and Europe

NASA Astrophysics Data System (ADS)

Rieder, H. E.; Fiore, A. M.; Fang, Y.; Staehelin, J.

2011-12-01

Over the past few decades, thresholds for national air quality standards, intended to protect public health and welfare, have been lowered repeatedly. At the same time observations, over Europe and the Eastern U.S., demonstrate that extreme air pollution events (high O3 and PM2.5) are typically associated with stagnation events. Recent work showed that in a changing climate high air pollution events are likely to increase in frequency and duration. Within this work we examine meteorological and surface ozone observations from CASTNet over the U.S. and EMEP over Europe and "idealized" simulations with the GFDL AM3 chemistry-climate model, which isolate the role of climate change on air quality. Specifically, we examine an "idealized 1990s" simulation, forced with 20-year mean monthly climatologies for sea surface temperatures and sea ice from observations for 1981-2000, and an "idealized 2090s" simulation forced by the observed climatologies plus the multi-model mean changes in sea surface temperature and sea ice simulated by 19 IPCC AR-4 models under the A1B scenario for 2081-2100. With innovative statistical tools (empirical orthogonal functions (EOFs) and statistics of extremes (EVT)), we analyze the frequency distribution of past, present and future extreme air pollution events over the Eastern United States and Europe. The upper tail of observed values at individual stations (e.g., within the CASTNet), i.e., the extremes (maximum daily 8-hour average (MDA8) O3>60ppb) are poorly described by a Gaussian distribution. However, further analysis showed that applying Peak-Over-Threshold-models, better capture the extremes and allows us to estimate return levels of pollution events above certain threshold values of interest. We next apply EOF analysis to identify regions that vary coherently within the ground-based monitoring networks. Over the United States, the first EOF obtained from the model in both the 1990s and 2090s idealized simulations identifies the Northeast as a region that varies coherently. Correlation analysis reveals that this EOF pattern is most strongly expressed in association with high surface temperature and high surface pressure conditions, consistent with previous work showing that observed O3 episodes over this area reflect the combined impacts of stagnation and increased chemical production. Next steps include the extension of this analysis applying EVT tools to the principal component time series associated with this EOF. The combination of EOF and EVT tools applied to the GFDL AM3 1990s vs. 2090s idealized simulations will enable us to quantify changes in the return levels of air pollution extremes. Therefore the combination of observational data and numerical and statistical models should allow us to identify key driving forces between high air pollution events and to estimate changes in the frequency of such events under different climate change scenarios.

Observed evolution of drought episodes assessed with the Standardized Precipitation Evapotranspiration Index (SPEI) over the Czech Republic

NASA Astrophysics Data System (ADS)

Potop, V.; Boroneana, C.; Mozny, M.; Stepanek, P.; Skalak, P.

2012-04-01

This paper investigates the spatial and temporal evolution of drought episodes assessed with the Standardized Precipitation Evapotranspiration Index (SPEI) over the Czech Republic. The SPEI were calculated from monthly records of mean temperature and precipitation totals using a dense network of 183 climatological stations for the period 1961-2010. The SPEI were calculated with various lags, 1, 3, 6, 12 and 24 months. The drought at these time scales is relevant for agricultural, hydrological and socio-economic impact, respectively. The study refers at the warm season of the year (April to September). The principal modes of variability of these five time scale SPEI were identified using the analysis of Empirical Orthogonal Functions (EOF). The explained variance of the leading EOF ranges between 71 and 61% as the time scale for calculating the SPEI increases from 1 month to 24 months. The explained variance of EOF2 and EOF3 ranges between 5 to 9% and 4 to 6%, respectively, as the SPEI is calculated for 1 to 24 months. Based on the spatial distribution of the EOF2 and EOF3 for all time scales of SPEI, which correspond to some extend to a regionalization previously used in other studies, we identified three climatically homogeneous regions, corresponding to the altitudes below 400 m, between 401 and 700 m and, above 700 m. These regions correspond to different land use types with mostly intensive agriculture, less intensive agriculture and limited agricultural production and mostly forested, respectively. For these three regions the frequency distribution of the SPEI values in 7 classes of drought category (%) were calculated based on station records in each region. The normal conditions represent around 65% out of the total values of SPEI for all times scales, in all three regions, while moderate drought and moderate wet conditions are almost equally distributed around 10.5 %. Differences in extremely dry conditions (5%) compared to extremely wet conditions (1.5 %) were observed when increasing the SPEI timescales. The drought is classified as local when covers up to 10% of the territory of the Czech Republic, widespread when covers 11-30% of the territory, very widespread when covers 31-50% of the territory and most extended when covers more than 50% of the country territory. We gratefully acknowledge the support of the Ministry of Education, Youth and Sports for projects OC10010.

What Causes the North Sea Level to Rise Faster over the Last Decade ?

NASA Astrophysics Data System (ADS)

Karpytchev, Mikhail; Letetrel, Camille

2013-04-01

We combined tide gauge records (PSMSL) and satellite altimetry data (TOPEX/POSEIDON-JASON 1-2) to reconstruct the mean level of the North Sea and the Norwegian Sea Shelf (NS-NSS) over 1950-2012. The reconstructed NS-NSS mean sea level fluctuations reveal a pronounced interannual variability and a strong sea level acceleration since the mid-1990's. In order to understand the causes of this acceleration, the NS-NSS mean sea level was cross-correlated with the North Atlantic Oscillation and Arctic Oscillation indices. While the interannual variability of the mean sea level correlates well with the NAO/AO indices, the observed acceleration in the NS-NSS mean level is not linked linearly to the NAO/AO fluctuations. On the other hand, the Empirical Orthogonal Functions (EOF) analysis of steric sea level variations in the eastern North Atlantic gives a dominant EOF pattern (55% of variance explained) that varies on a decadal scale very closely to the NS-NSS mean level flcutuations. Also, the amplification in the temporal amplitude of the dominant steric sea level EOF corresponds to the acceleration observed in the NS-NSS mean sea level signal. This suggests that decadal variations in the mean level of the North Sea - the Norwegian Sea Shelf reflect changes in the Subpolar Front currents (Rossby, 1996).

A Canonical Ensemble Correlation Prediction Model for Seasonal Precipitation Anomaly

NASA Technical Reports Server (NTRS)

Shen, Samuel S. P.; Lau, William K. M.; Kim, Kyu-Myong; Li, Guilong

2001-01-01

This report describes an optimal ensemble forecasting model for seasonal precipitation and its error estimation. Each individual forecast is based on the canonical correlation analysis (CCA) in the spectral spaces whose bases are empirical orthogonal functions (EOF). The optimal weights in the ensemble forecasting crucially depend on the mean square error of each individual forecast. An estimate of the mean square error of a CCA prediction is made also using the spectral method. The error is decomposed onto EOFs of the predictand and decreases linearly according to the correlation between the predictor and predictand. This new CCA model includes the following features: (1) the use of area-factor, (2) the estimation of prediction error, and (3) the optimal ensemble of multiple forecasts. The new CCA model is applied to the seasonal forecasting of the United States precipitation field. The predictor is the sea surface temperature.

Statistical downscaling forecast of Chinese winter temperature based on the autumn SST anomalies

NASA Astrophysics Data System (ADS)

Lu, J.

2017-12-01

This study investigates the impacts of the autumn sea surface temperature anomalies (SSTA) on interannual variations of Chinese winter temperature, and discusses the potential predictability of December-January-February (DJF) 2-m air temperature anomalies (TSA) over China based on the intimate linkage between the DJF TSA and autumn SSTA. According to the Empirical Orthogonal Function (EOF) analysis, three leading EOF modes jointly account for 80% of the total TSA variances and are characterized by a homogeneous spatial pattern, a north-south seesaw and a cross structure. The first three EOFs exhibit a stable feature revealed by cross-validation, suggesting the potential predictability of the DJF TSA. The EOF1 mode is influenced by changes in the intensities of the Siberian High (SH), East Asian winter monsoon (EAWM) and East Asian Trough related to an Eurasian pattern teleconnection, which can be tracked back to September-October-November (SON) SSTA associated with two SSTA tripole patterns in the North Pacific and North Atlantic, a dipole mode in the Indian Ocean and an ENSO-like mode in the equatorial and subtropical Pacific. However, the Arctic Oscillation plays an important role in the second mode. The teleconnection connecting the atmospheric circulation anomalies in two hemispheres indicates that the configuration of global SON SSTA induces the two annular modes and causes a TSA oscillation between the northern and southern parts of China. The third mode is related to the westward shift of the SH and western pathway EAWM, which are attributed to two dipole modes in the North Pacific and South Pacific, Atlantic Multidecadal Oscillation and Indian Ocean Basin Mode. Therefore a physically-based statistical model is established based on autumn SSTA indices. Cross-validation suggests that this statistical downscaling forecast model shows a good performance in predicting the DJF TSA.

Numerical Study on Interdecadal Modulations of ENSO-related Spring Rainfall over South China by the Pacific Decadal Oscillation

NASA Astrophysics Data System (ADS)

MAO, J.; WU, X.

2017-12-01

The spatio-temporal variations of eastern China spring rainfall are identified via empirical orthogonal function (EOF) analysis of rain-gauge (gridded) precipitation datasets for the period 1958-2013 (1920-2013). The interannual variations of the first two leading EOF modes are linked with the El Niño-Southern Oscillation (ENSO), with this linkage being modulated by the Pacific Decadal Oscillation (PDO). The EOF1 mode, characterized by predominant rainfall anomalies from the Yangtze River to North China (YNC), is more likely associated with out-of-phase PDO-ENSO events [i.e., El Niño during cold PDO (EN_CPDO) and La Niña during warm PDO (LN_WPDO)]. The sea surface temperature anomaly (SSTA) distributions of EN_CPDO (LN_WPDO) events induce a significant anomalous anticyclone (cyclone) over the western North Pacific stretching northwards to the Korean Peninsula and southern Japan, resulting in anomalous southwesterlies (northeasterlies) prevailing over eastern China and above-normal (below-normal) rainfall over YNC. In contrast, EOF2 exhibits a dipole pattern with predominantly positive rainfall anomalies over southern China along with negative anomalies over YNC, which is more likely connected to in-phase PDO-ENSO events [i.e., El Niño during warm PDO (EN_WPDO) and La Niña during cold PDO (LN_CPDO)]. EN_WPDO (LN_CPDO) events force a southwest-northeast oriented dipole-like circulation pattern leading to significant anomalous southwesterlies (northeasterlies) and above-normal (below-normal) rainfall over southern China. Numerical experiments with the CAM5 model forced by the SSTA patterns of EN_WPDO and EN_CPDO events reproduce reasonably well the corresponding anomalous atmospheric circulation patterns and spring rainfall modes over eastern China, validating the related mechanisms.

Sea ice algae chlorophyll a concentrations derived from under-ice spectral radiation profiling platforms

NASA Astrophysics Data System (ADS)

Lange, Benjamin A.; Katlein, Christian; Nicolaus, Marcel; Peeken, Ilka; Flores, Hauke

2016-12-01

Multiscale sea ice algae observations are fundamentally important for projecting changes to sea ice ecosystems, as the physical environment continues to change. In this study, we developed upon previously established methodologies for deriving sea ice-algal chlorophyll a concentrations (chl a) from spectral radiation measurements, and applied these to larger-scale spectral surveys. We conducted four different under-ice spectral measurements: irradiance, radiance, transmittance, and transflectance, and applied three statistical approaches: Empirical Orthogonal Functions (EOF), Normalized Difference Indices (NDI), and multi-NDI. We developed models based on ice core chl a and coincident spectral irradiance/transmittance (N = 49) and radiance/transflectance (N = 50) measurements conducted during two cruises to the central Arctic Ocean in 2011 and 2012. These reference models were ranked based on two criteria: mean robustness R2 and true prediction error estimates. For estimating the biomass of a large-scale data set, the EOF approach performed better than the NDI, due to its ability to account for the high variability of environmental properties experienced over large areas. Based on robustness and true prediction error, the three most reliable models, EOF-transmittance, EOF-transflectance, and NDI-transmittance, were applied to two remotely operated vehicle (ROV) and two Surface and Under-Ice Trawl (SUIT) spectral radiation surveys. In these larger-scale chl a estimates, EOF-transmittance showed the best fit to ice core chl a. Application of our most reliable model, EOF-transmittance, to an 85 m horizontal ROV transect revealed large differences compared to published biomass estimates from the same site with important implications for projections of Arctic-wide ice-algal biomass and primary production.

An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations

PubMed Central

Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J. Harry

2016-01-01

Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types. PMID:27472383

An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations.

PubMed

Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J Harry

2016-01-01

Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types.

Hindcast of extreme sea states in North Atlantic extratropical storms

NASA Astrophysics Data System (ADS)

Ponce de León, Sonia; Guedes Soares, Carlos

2015-02-01

This study examines the variability of freak wave parameters around the eye of northern hemisphere extratropical cyclones. The data was obtained from a hindcast performed with the WAve Model (WAM) model forced by the wind fields of the Climate Forecast System Reanalysis (CFSR). The hindcast results were validated against the wave buoys and satellite altimetry data showing a good correlation. The variability of different wave parameters was assessed by applying the empirical orthogonal functions (EOF) technique on the hindcast data. From the EOF analysis, it can be concluded that the first empirical orthogonal function (V1) accounts for greater share of variability of significant wave height (Hs), peak period (Tp), directional spreading (SPR) and Benjamin-Feir index (BFI). The share of variance in V1 varies for cyclone and variable: for the 2nd storm and Hs V1 contains 96 % of variance while for the 3rd storm and BFI V1 accounts only for 26 % of variance. The spatial patterns of V1 show that the variables are distributed around the cyclones centres mainly in a lobular fashion.

Growth of Errors and Uncertainties in Medium Range Ensemble Forecasts of U.S. East Coast Cool Season Extratropical Cyclones

NASA Astrophysics Data System (ADS)

Zheng, Minghua

Cool-season extratropical cyclones near the U.S. East Coast often have significant impacts on the safety, health, environment and economy of this most densely populated region. Hence it is of vital importance to forecast these high-impact winter storm events as accurately as possible by numerical weather prediction (NWP), including in the medium-range. Ensemble forecasts are appealing to operational forecasters when forecasting such events because they can provide an envelope of likely solutions to serve user communities. However, it is generally accepted that ensemble outputs are not used efficiently in NWS operations mainly due to the lack of simple and quantitative tools to communicate forecast uncertainties and ensemble verification to assess model errors and biases. Ensemble sensitivity analysis (ESA), which employs a linear correlation and regression between a chosen forecast metric and the forecast state vector, can be used to analyze the forecast uncertainty development for both short- and medium-range forecasts. The application of ESA to a high-impact winter storm in December 2010 demonstrated that the sensitivity signals based on different forecast metrics are robust. In particular, the ESA based on the leading two EOF PCs can separate sensitive regions associated with cyclone amplitude and intensity uncertainties, respectively. The sensitivity signals were verified using the leave-one-out cross validation (LOOCV) method based on a multi-model ensemble from CMC, ECMWF, and NCEP. The climatology of ensemble sensitivities for the leading two EOF PCs based on 3-day and 6-day forecasts of historical cyclone cases was presented. It was found that the EOF1 pattern often represents the intensity variations while the EOF2 pattern represents the track variations along west-southwest and east-northeast direction. For PC1, the upper-level trough associated with the East Coast cyclone and its downstream ridge are important to the forecast uncertainty in cyclone strength. The initial differences in forecasting the ridge along the west coast of North America impact the EOF1 pattern most. For PC2, it was shown that the shift of the tri-polar structure is most significantly related to the cyclone track forecasts. The EOF/fuzzy clustering tool was applied to diagnose the scenarios in operational ensemble forecast of East Coast winter storms. It was shown that the clustering method could efficiently separate the forecast scenarios associated with East Coast storms based on the 90-member multi-model ensemble. A scenario-based ensemble verification method has been proposed and applied it to examine the capability of different EPSs in capturing the analysis scenarios for historical East Coast cyclone cases at lead times of 1-9 days. The results suggest that the NCEP model performs better in short-range forecasts in capturing the analysis scenario although it is under-dispersed. The ECMWF ensemble shows the best performance in the medium range. The CMC model is found to show the smallest percentage of members in the analysis group and a relatively high missing rate, suggesting that it is less reliable regarding capturing the analysis scenario when compared with the other two EPSs. A combination of NCEP and CMC models has been found to reduce the missing rate and improve the error-spread skill in medium- to extended-range forecasts. Based on the orthogonal features of the EOF patterns, the model errors for 1-6-day forecasts have been decomposed for the leading two EOF patterns. The results for error decomposition show that the NCEP model tends to better represent both EOF1 and EOF2 patterns by showing less intensity and displacement errors during 1-3 days. The ECMWF model is found to have the smallest errors in both EOF1 and EOF2 patterns during 4-6 days. We have also found that East Coast cyclones in the ECMWF forecast tend to be towards the southwest of the other two models in representing the EOF2 pattern, which is associated with the southwest-northeast shifting of the cyclone. This result suggests that ECMWF model may have a tendency to show a closer-to-shore solution in forecasting East Coast winter storms. The downstream impacts of Rossby wave packets (RWPs) on the predictability of winter storms are investigated to explore the source of ensemble uncertainties. The composited RWPA anomalies show that there are enhanced RWPs propagating across the Pacific in both large-error and large-spread cases over the verification regions. There are also indications that the errors might propagate with a speed comparable with the group velocity of RWPs. Based on the composite results as well as our observations of the operation daily RWPA, a conceptual model of errors/uncertainty development associated with RWPs has been proposed to serve as a practical tool to understand the evolution of forecast errors and uncertainties associated with the coherent RWPs originating from upstream as far as western Pacific. (Abstract shortened by ProQuest.).

An Empirical Orthogonal Function Reanalysis of the Northern Polar External and Induced Magnetic Field During Solar Cycle 23

NASA Astrophysics Data System (ADS)

Shore, R. M.; Freeman, M. P.; Gjerloev, J. W.

2018-01-01

We apply the method of data-interpolating empirical orthogonal functions (EOFs) to ground-based magnetic vector data from the SuperMAG archive to produce a series of month length reanalyses of the surface external and induced magnetic field (SEIMF) in 110,000 km2 equal-area bins over the entire northern polar region at 5 min cadence over solar cycle 23, from 1997.0 to 2009.0. Each EOF reanalysis also decomposes the measured SEIMF variation into a hierarchy of spatiotemporal patterns which are ordered by their contribution to the monthly magnetic field variance. We find that the leading EOF patterns can each be (subjectively) interpreted as well-known SEIMF systems or their equivalent current systems. The relationship of the equivalent currents to the true current flow is not investigated. We track the leading SEIMF or equivalent current systems of similar type by intermonthly spatial correlation and apply graph theory to (objectively) group their appearance and relative importance throughout a solar cycle, revealing seasonal and solar cycle variation. In this way, we identify the spatiotemporal patterns that maximally contribute to SEIMF variability over a solar cycle. We propose this combination of EOF and graph theory as a powerful method for objectively defining and investigating the structure and variability of the SEIMF or their equivalent ionospheric currents for use in both geomagnetism and space weather applications. It is demonstrated here on solar cycle 23 but is extendable to any epoch with sufficient data coverage.

Experiments in Reconstructing Twentieth-Century Sea Levels

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Douglas, Bruce C.

2011-01-01

One approach to reconstructing historical sea level from the relatively sparse tide-gauge network is to employ Empirical Orthogonal Functions (EOFs) as interpolatory spatial basis functions. The EOFs are determined from independent global data, generally sea-surface heights from either satellite altimetry or a numerical ocean model. The problem is revisited here for sea level since 1900. A new approach to handling the tide-gauge datum problem by direct solution offers possible advantages over the method of integrating sea-level differences, with the potential of eventually adjusting datums into the global terrestrial reference frame. The resulting time series of global mean sea levels appears fairly insensitive to the adopted set of EOFs. In contrast, charts of regional sea level anomalies and trends are very sensitive to the adopted set of EOFs, especially for the sparser network of gauges in the early 20th century. The reconstructions appear especially suspect before 1950 in the tropical Pacific. While this limits some applications of the sea-level reconstructions, the sensitivity does appear adequately captured by formal uncertainties. All our solutions show regional trends over the past five decades to be fairly uniform throughout the global ocean, in contrast to trends observed over the shorter altimeter era. Consistent with several previous estimates, the global sea-level rise since 1900 is 1.70 +/- 0.26 mm/yr. The global trend since 1995 exceeds 3 mm/yr which is consistent with altimeter measurements, but this large trend was possibly also reached between 1935 and 1950.

Southern hemisphere low level wind circulation statistics from the Seasat scatterometer

NASA Technical Reports Server (NTRS)

Levy, Gad

1994-01-01

Analyses of remotely sensed low-level wind vector data over the Southern Ocean are performed. Five-day averages and monthly means are created and the month-to-month variability during the winter (July-September) of 1978 is investigated. The remotely sensed winds are compared to the Australian Bureau of Meteorology (ABM) and the National Meteorological Center (NMC) surface analyses. In southern latitudes the remotely sensed winds are stronger than what the weather services' analyses suggest, indicating under-estimation by ABM and NMC in these regions. The evolution of the low-level jet and the major stormtracks during the season are studied and different flow regimes are identified. The large-scale variability of the meridional flow is studied with the aid of empirical orthogonal function (EOF) analysis. The dominance of quasi-stationary wave numbers 3,4, and 5 in the winter flows is evident in both the EOF analysis and the mean flow. The signature of an exceptionally strong blocking situation is evident in July and the special conditions leading to it are discussed. A very large intraseasonal variability with different flow regimes at different months is documented.

Constraining the variability of optical properties in the Santa Barbara Channel, CA: A phytoplankton story

NASA Astrophysics Data System (ADS)

Barron, Rebecca Katherine

The research presented in this dissertation evaluates the direct relationships of phytoplankton community composition and inherent optical properties (IOP); that is, the absorption and scattering of light in the ocean. Phytoplankton community composition affect IOPs in both direct and indirect ways, thus creating challenges for optical measurements of biological and biogeochemical properties in aquatic systems. Studies were performed in the Santa Barbara Channel (SBC), CA where an array of optical and biogeochemical measurements were made. Phytoplankton community structure was characterized by an empirical orthogonal functional analysis (EOF) using phytoplankton accessory pigments. The results showed that phytoplankton community significantly correlated to all IOPs, e.g. phytoplankton specific absorption, detrital absorption, CDOM absorption and particle backscattering coefficients. Furthermore, the EOF analysis was unique in splitting the microphytoplankton size class into separate diatom and dinoflagellate regimes allowing for assessment optical property differences within the same size class, a technique previously not systematically achievable. The phytoplankton functional group dinoflagellates were particularly influential to IOPs in surprising ways. Dinoflagellates showed higher backscattering efficiencies than would be predicted based on Mie theory, and significantly influenced CDOM absorption via direct association with dissolved mycosproine-like amino acid absorption (MAA) peaks in CDOM spectra. A new index was developed in this work to quantify MAA absorption peaks in CDOM spectra, and was named the MAA Index. Prior to this research dissolved MAA absorption in natural waters was never quantified, and CDOM data containing these peaks were often disregarded and discarded from analysis. CDOM dynamics in the SBC were assessed for a 15-year study period, and this work shows that significantly large MAA Index values, e.g. MAA Index > 1, were present in approximately 16% of surface water data. Variability in CDOM spectral shape was quantified using the EOF technique, and regression analysis with EOF outputs showed that CDOM absorption intensity and spectral shape were well correlated dinoflagellate presence. Furthermore, results showed that phytoplankton biomass played a secondary role in relation to CDOM absorption, and that variability in CDOM absorption coefficients were primarily driven by community composition. CDOM quality in the SBC was also assessed using CDOM fluorescence properties via excitation emission matrix spectroscopy (EEMS). The EEMS data was analyzed using a multivariate statistical procedure, again, an EOF analysis, to identify three dominant CDOM source regimes: the surface pelagic regime, deep-water (up to 300 m) regime and kelp forest pelagic regime. This work also found that while CDOM absorption coefficient was strongly influence by which phytoplankton groups were present, DOM quality was characterized more so by the amount of phytoplankton biomass, hence indicating strong microbial component to DOM production. Lastly, with the use of the EEMS data, and characterization of CDOM absorption properties, e.g. spectral slope, S, slope ratio, SR, specific UV-absorbance, SUVA and MAA Index, we found that terrestrial sources of CDOM were very limited in the SBC. Based on this research, mineral particle concentrations that significantly correlated with IOPs were thought to be associated with suspended sediments from shoaling of the continental shelf rather than from stream/river influence. Thus, the SBC is a unique, optically complex ocean system where IOP dynamics, thus remote sensing reflectance, are strongly influenced by shifts in phytoplankton community structure.

Toward Better Intraseasonal and Seasonal Prediction: Verification and Evaluation of the NOGAPS Model Forecasts

DTIC Science & Technology

2013-09-30

Circulation (HC) in terms of the meridional streamfunction. The interannual variability of the Atlantic HC in boreal summer was examined using the EOF...large-scale circulations in the NAVGEM model and the source of predictability for the seasonal variation of the Atlantic TCs. We have been working...EOF analysis of Meridional Circulation (JAS). (a) The leading mode (M1); (b) variance explained by the first 10 modes. 9

Exploring the Dominant Modes of Shoreline Change Along the Central Florida Atlantic Coast

NASA Astrophysics Data System (ADS)

Conlin, M. P.; Adams, P. N.; Jaeger, J. M.; MacKenzie, R.

2017-12-01

Geomorphic change within the littoral zone can place communities, ecosystems, and critical infrastructure at risk as the coastal environment responds to changes in sea level, sediment supply, and wave climate. At NASA's Kennedy Space Center near Cape Canaveral, Florida, chronic shoreline retreat currently threatens critical launch infrastructure, but the spatial (alongshore) pattern of this hazard has not been well documented. During a 5-year monitoring campaign (2009-2014), 86 monthly and rapid-response RTK GPS surveys were completed along this 11 km-long coastal reach in order to monitor and characterize shoreline change and identify links between ocean forcing and beach morphology. Results indicate that the study area can be divided into four behaviorally-distinct alongshore regions based on seasonal variability in shoreline change, mediated by the complex offshore bathymetry of the Cape Canaveral shoals. In addition, seasonal erosion/accretion cycles are regularly interrupted by large erosive storm events, especially during the anomalous wave climates produced during winter Nor'Easter storms. An effective tool for analyzing multidimensional datasets like this one is Empirical Orthogonal Function (EOF) analysis, a technique to determine the dominant spatial and temporal signals within a dataset. Using this approach, it is possible to identify the main time and space scales (modes) along which coastal changes are occurring. Through correlation of these changes with oceanographic forcing mechanisms, we are enabled to infer the principal drivers of shoreline change at this site. Here, we document the results of EOF analysis applied to the Cape Canaveral shoreline change dataset, and further correlate the results of this analysis with oceanographic forcings in order to reveal the dominant modes as well as drivers of coastal variability along the central Atlantic coast of Florida. This EOF-based analysis, which is the first such analysis in the region, is shedding light on the hazards that most affect Florida's coastal communities and the scales at which coastal planners and stakeholders should focus protection efforts.

Open-access and multi-directional electroosmotic flow chip for positioning heterotypic cells.

PubMed

Terao, Kyohei; Kitazawa, Yuko; Yokokawa, Ryuji; Okonogi, Atsuhito; Kotera, Hidetoshi

2011-04-21

We propose a novel method of cell positioning using electroosmotic flow (EOF) to analyze cell-cell interactions. The EOF chip has an open-to-air configuration, is equipped with four electrodes to induce multi-directional EOF, and allows access of tools for liquid handling and of physical probes for cell measurements. Evaluation of the flow within this chip indicated that it controlled hydrodynamic transport of cells, in terms of both speed and direction. We also evaluated cell viability after EOF application and determined appropriate conditions for cell positioning. Two cells were successively positioned in pocket-like microstructures, one in each micropocket, by controlling the EOF direction. As an experimental demonstration, we observed contact interactions between two individual cells through gap junction channels. The EOF chip should provide ways to elucidate various cell-cell interactions between heterotypic cells.

Field-effect Flow Control in Polymer Microchannel Networks

NASA Technical Reports Server (NTRS)

Sniadecki, Nathan; Lee, Cheng S.; Beamesderfer, Mike; DeVoe, Don L.

2003-01-01

A new Bio-MEMS electroosmotic flow (EOF) modulator for plastic microchannel networks has been developed. The EOF modulator uses field-effect flow control (FEFC) to adjust the zeta potential at the Parylene C microchannel wall. By setting a differential EOF pumping rate in two of the three microchannels at a T-intersection with EOF modulators, the induced pressure at the intersection generated pumping in the third, field-free microchannel. The EOF modulators are able to change the magnitude and direction of the pressure pumping by inducing either a negative or positive pressure at the intersection. The flow velocity is tracked by neutralized fluorescent microbeads in the microchannels. The proof-of-concept of the EOF modulator described here may be applied to complex plastic ,microchannel networks where individual microchannel flow rates are addressable by localized induced-pressure pumping.

[Effect of climate change on the fisheries conununity pattern in the overwintering ground of open waters of northern East China Sea].

PubMed

Liu, Zun-lei; Yuan, Xing-wei; Yang, Lin-lin; Yan, Li-ping; Tian, Yong-jun; Chen, Jia-hua

2015-03-01

Data sets of 26 fisheries target species from the fishery-depen-dent and fishery-independent surveys in the overwintering ground of open waters of northern East China Sea (OW-NECS), combined sea surface temperature (SST), were used to examine the links between diversity index, pattern of common variability and climate changes based on the principal component analysis (PCA) and generalized additive model (GAM). The results showed that the shift from a cold regime to a warm regime was detected in SST during the 1970s-2011 with step changes around 1982/ 1983. SST increased during the cold regime and the warm regime before 1998 (warming trend period, 1972-1998), and decreased during the warm regime after 1998 (cooling trend period, 1999-2011). Shannon diversity index was largely dependent on the filefish, which contributed up to 50% of the total production as a single species, with low diversity in the waters of the OW-NECS, during the late 1980s and early 1990s. Excluding the filefish, the diversity index linearly increased and decreased during 1972-1998 and 1999-2011, respectively. The variation pattern generally corresponds with the trend in water temperature, strongly suggesting the effect of the SST on the diversity. The first two components (PC1 and PC2) of PCA for target species, which accounted for 32.43% of the total variance, showed evident decadal variation patterns with a step change during 1992-1999 and inter-annual variability with short-period fluctuation, respectively. It seems that PC1 was associated with large scale climatic change, while PC2 was related to inter-annual oceanographic variability such as ENSO events. Linear fitting results showed winEOF1 had significant effect on PC1, and GAM analysis for PC1 showed that winter EOF1 (winEOF1) and summer EOF2 (sumEOF2) can explain 88.9% of the total variance. Nonlinear effect was also found between PC2 and win EOF1, indicating that the fish community structure, which had predominantly decadal/inter-annual variation patterns, was influenced by inter-annual variations in oceanographic conditions.

Transport of the Norwegian Atlantic current as determined from satellite altimetry

NASA Technical Reports Server (NTRS)

Pistek, Pavel; Johnson, Donald R.

1992-01-01

Relatively warm and salty North Atlantic surface waters flow through the Faeroe-Shetland Channel into the higher latitudes of the Nordic Seas, preserving an ice-free winter environment for much of the exterior coast of northern Europe. This flow was monitored along the Norwegian coast using Geosat altimetry on two ascending arcs during the Exact Repeat Mission in 1987-1989. Concurrent undertrack CTD surveys were used to fix a reference surface for the altimeter-derived SSH anomalies, in effect creating time series of alongtrack surface dynamic height topographies. Climatologic CTD casts were then used, with empirical orthogonal function (EOF) analysis, to derive relationships between historical surface dynamic heights and vertical temperature and salinity profiles. Applying these EOF relationships to the altimeter signals, mean transports of volume, heat, and salt were calculated at approximately 2.9 Sverdrups, 8.1 x 10 exp 11 KCal/s and 1.0 x 10 exp 8 Kg/s, respectively. Maximum transports occurred in February/March and minimum in July/August.

A Survey of Synoptic Waves over West Africa

NASA Astrophysics Data System (ADS)

Cheng, Yuan-Ming; Thorncroft, Chris D.; Kiladis, George N.

2017-04-01

Motivated by the pronounced wave-to-wave variability in African easterly wave (AEW) circulation, the three-dimensional structure of synoptic waves over West Africa is revisited with an Empirical Orthogonal Function (EOF) approach to isolate the dominant wave pattern. In this talk we present results of EOF analyses conducted with brightness temperature (Tb) derived from satellite observation and meridional wind at multiple levels from reanalysis data to examine the characteristics and variability of synoptic waves. The structure of waves is extracted by projecting the wind fields and Tb onto the principle components associated with EOF patterns of appropriately filtered parameters. The Tb EOF shows a confined AEW circulation centered around 7.5°N and a distinct evolution of convection within the wave in line with previous research. However, in striking contrast to the confined flow pattern in the Tb EOF, the EOF of 700-hPa meridional wind is distinguished by a meridionally broad AEW circulation. While the peak in circulation is centered around 10°N, there is marked cross-equatorial flow that is associated with an antisymmetric geopotential signature across the equator. This suggests the presence of a mixed Rossby-gravity wave (MRG) structure consistent with Matsuno's shallow water theory. Granted that the vast majority of studies on MRGs focus on the central and western Pacific region, this "hybrid" between AEWs and MRGs over West Africa and Atlantic sector has received little attention and more work regarding the nature and causes of its wave structure and behavior is needed. In addition, an upper-level synoptic wave is captured by EOFs of 200-hPa meridional wind. The kinematic fields reveal a continental-scale wave straddling the equator that resembles an MRG. This upper-level MRG appears to develop in situ over the Horn of Africa and intensifies as it moves across the continent. The associated lower-level structure shows an AEW-like circulation but with a larger spatial extent. This finding motivates the need for more in-depth investigations of synoptic wave variability over the region including an assessment of the direction of causality between the upper-level MRG and the lower-level AEW. This study highlights the various synoptic wave structures over West Africa and their interaction with AEWs. The results suggest the variability of AEW activity could be modulated by, in addition to the large-scale environment, other synoptic waves in the region. We will pursue the EOF approach to shed light on the characteristics and causes of the variability in synoptic wave activity over West Africa.

Solar and Heliospheric Observatory (SOHO) Experimenters' Operations Facility (EOF)

NASA Technical Reports Server (NTRS)

Larduinat, Eliane; Potter, William

1994-01-01

This paper describes the SOHO Instrumenters' Operations Facility (EOF) project. The EOF is the element of the SOHO ground system at the Goddard Space Flight Center that provides the interface between the SOHO scientists and the other ground system elements. This paper first describes the development context of the SOHO EOF. It provides an overview of the SOHO mission within the International Solar-Terrestrial Physics (ISTP) project, and discusses the SOHO scientific objectives. The second part of this paper presents the implementation of the SOHO EOF, its innovative features, its possible applications to other missions, and its potential for use as part of a fully integrated ground control system.

An Alternating Current Electroosmotic Pump Based on Conical Nanopore Membranes.

PubMed

Wu, Xiaojian; Ramiah Rajasekaran, Pradeep; Martin, Charles R

2016-04-26

Electroosmotic flow (EOF) is used to pump solutions through microfluidic devices and capillary electrophoresis columns. We describe here an EOF pump based on membrane EOF rectification, an electrokinetic phenomenon we recently described. EOF rectification requires membranes with asymmetrically shaped pores, and conical pores in a polymeric membrane were used here. We show here that solution flow through the membrane can be achieved by applying a symmetrical sinusoidal voltage waveform across the membrane. This is possible because the alternating current (AC) carried by ions through the pore is rectified, and we previously showed that rectified currents yield EOF rectification. We have investigated the effect of both the magnitude and frequency of the voltage waveform on flow rate through the membrane, and we have measured the maximum operating pressure. Finally, we show that operating in AC mode offers potential advantages relative to conventional DC-mode EOF pumps.

[Residue of organic fluorine pollutants in hair and nails collected from Tianjin].

PubMed

Yao, Dan; Zhang, Hong; Chai, Zhi-Fang; Shen, Jin-Can; Yang, Bo; Wang, Yan-Ping; Liu, Guo-Qing

2013-02-01

In order to explore the residue and distributions of organic fluorine pollutants in hair and nails, the residue levels of total fluorine (TF), extractable organic fluorine (EOF) and perfluorinated chemicals (PFCs) in hair and nails collected from Tianjin adults were measured by the cyclic neutron activation analysis (CNAA) combined with the high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results showed that inorganic fluorine (mean: 2.0 mg.kg-1, 4.5 mg.kg-1) was the primary fluorine in TF while EOF(mean: 0.7 mg.kg-1, 1.8 mg.kg-1) was minor. The average amount of identified fluorine (IF) was 0.038 mg.kg-1 in hair and 0.047 mg.kg-1 in nails, accounting or 7.1% (2.6%-16%) and 3.5% (1.1%-11%) of EOF, respectively, which indicated that more than 84% of EOF was unknown. The major residue in hair and nails were medium-and short-chain PFCs,in which perfluorooctane sulfonate, perfluorooctanoic acid and perfluorononanoic acid were the main species. TF, EOF and IF levels in dyed and permed hair were significantly higher than untreated hair (P <0.05), and the concentrations of Sigma PFCs in hair and nails showed no difference between genders. With significantly higher levels of sigma PFCs and PFOS residues than hair (P <0.01), nails could potentially become a more sensitive bioindicator for the exposure level of PFCs in human.

Decadal variability of the position and strength of the South Atlantic Convergence Zone and its relationship to precipitation variability and extremes over Southeastern Brazil

NASA Astrophysics Data System (ADS)

Zilli, M. T.; Carvalho, L. V.; Lintner, B. R.

2016-12-01

The South Atlantic Convergence Zone (SACZ) is a diagonally oriented zone of low-level convergence, convective cloudiness, and rainfall originating over South America and extending to the southeast over the Atlantic Ocean. The objective of this study is to investigate the role of variability in the position and strength of the SACZ in causing precipitation variability and extremes over the southeastern Brazilian coast (SE). To that end, we perform Empirical Orthogonal Function (EOF) analysis of total summer (DJF) precipitation from 1979 to 2013, using the National Center for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), at 0.5° spatial resolution. The first mode (EOF-1) explains 22.7% of total variance and is characterized by a dipole-like structure, with opposite signs over central South America and over central South Atlantic along the northern margin of the SACZ. The time-coefficient or principal component of EOF-1 indicates a transition from a predominantly negative phase over 1999 to 2005 to a predominantly positive phase after 2006. The positive phase is associated with an increase in total precipitation over the continent and a reduction over the central South Atlantic, along the northern margin of the SACZ. These results provide evidence of the poleward shift of the SACZ and weakening of convergence along its northern margin over the past decade, consistent with the observed recent trends in extreme precipitation over SE. Compositing reanalysis fields with respect to the PC of EOF-1 suggests changes in moisture availability and circulation that could have affected precipitation regimes over SE. In particular, an increase in available precipitable water may have enhanced convective activity over the southern portion of SE Brazil, whereas the weakening of the northerly winds may be responsible for the weakening of convergence over the northern flank of the SACZ, inhibiting convection in this region.

Coherent response of the Indo-African boreal summer monsoon to Pacific SST captured in Ethiopian rain δ18O

NASA Astrophysics Data System (ADS)

Madhavan, M.; Palliyil, L. R.; Ramesh, R.

2017-12-01

Pacific Sea Surface Temperature (SST) plays an important role in the inter-annual to inter-decadal variability of boreal monsoons. We identified a common mode of inter annual variability in the Indian and African boreal summer monsoon (June to September) rainfalls, which is linked to Pacific SSTs, using Empirical Orthogonal Function (EOF) analysis. Temporal coefficients (Principle component: PC1) of the leading mode of variability (EOF-1) is well correlated with the Indian summer monsoon rainfall and Sahel rainfall. About forty year long monthly observations of δ18O (and δD) at Addis Ababa, Ethiopia show a strong association with PC1 (r=0.69 for δ18O and r=0.75 for δD). Analysis of SST, sea level pressure and lower tropospheric winds suggest that 18O depletion in Ethiopian rainfall (and wet phases of PC1) is associated with cooler eastern tropical Pacific and warmer western Pacific and strengthening of Pacific subtropical high in both the hemispheres. Associated changes in the trade winds cause enhanced westerly moisture transport into the Indian subcontinent and northern Africa and cause enhanced rainfall. The intrusion of Atlantic westerly component of moisture transport at Addis Ababa during wet phases of PC1 is clearly recorded in δ18O of rain. We also observe the same common mode of variability (EOF1) of Indo-African boreal summer monsoon rain on decadal time scales. A 100 year long δ18O record of actively growing speleothem from the Mechara cave, Ethiopia, matches very well with the PC1 on the decadal time scale. This highlights the potential of speleothem δ18O and leaf wax δD from Ethiopia to investigate the natural variability and teleconnections of Indo-African boreal monsoon.

Electroosmotic Flow Reversal Outside Glass Nanopores

PubMed Central

2015-01-01

We report observations of a striking reversal in the direction of electroosmotic flow (EOF) outside a conical glass nanopore as a function of salt concentration. At high ionic strengths (>100 mM), we observe EOF in the expected direction as predicted by classical electrokinetic theory, while at low salt concentrations (<1 mM) the direction of the flow is reversed. The critical crossover salt concentration depends on the pore diameter. Finite-element simulations indicate a competition between the EOF generated from the inner and outer walls of the pore, which drives flows in opposite directions. We have developed a simple analytical model which reveals that, as the salt concentration is reduced, the flow rates inside the pore are geometrically constrained, whereas there is no such limit for flows outside the pore. This model captures all of the essential physics of the system and explains the observed data, highlighting the key role the external environment plays in determining the overall electroosmotic behavior. PMID:25490120

Reconstruction from EOF analysis of SMOS salinity data in Mediterranean Sea

NASA Astrophysics Data System (ADS)

Parard, Gaelle; Alvera-Azcárate, Aida; Barth, Alexander; Olmedo, Estrella; Turiel, Antonio; Becker, Jean-Marie

2017-04-01

Sea Surface Salinity (SSS) data from the Soil Moisture and Ocean Salinity (SMOS) mission is reconstructed in the North Atlantic and the Mediterranean Sea using DINEOF (Data Interpolating Empirical Orthogonal Functions). We used the satellite data Level 2 from SMOS Barcelona Expert Centre between 2011 and 2015. DINEOF is a technique that reconstructs missing data and removes noise by retaining only an optimal set of EOFs. DINEOF analysis is used to detect and remove outliers from the SMOS SSS daily field. The gain obtained with DINEOF method and L2 SMOS data give a higher spatial and temporal resolution between 2011 and 2015, allow to study the SSS variability from daily to seasonal resolution. In order to improve the SMOS salinity data reconstruction we combine with other parameters measured from satellite such chlorophyll, sea surface temperature, precipitation and CDOM variability. After a validation of the SMOS satellite data reconstruction with in situ data (CTD, Argo float salinity measurement) in the North Atlantic and Mediterranean Sea, the main SSS processes and their variability are studied. The gain obtained with the higher spatial and temporal resolution with SMOS salinity data give assess to study the characteristics of oceanic structures in North Atlantic and Mediterranean Sea.

Effect of nanostructures orientation on electroosmotic flow in a microfluidic channel

NASA Astrophysics Data System (ADS)

Eng Lim, An; Lim, Chun Yee; Cheong Lam, Yee; Taboryski, Rafael; Rui Wang, Shu

2017-06-01

Electroosmotic flow (EOF) is an electric-field-induced fluid flow that has numerous micro-/nanofluidic applications, ranging from pumping to chemical and biomedical analyses. Nanoscale networks/structures are often integrated in microchannels for a broad range of applications, such as electrophoretic separation of biomolecules, high reaction efficiency catalytic microreactors, and enhancement of heat transfer and sensing. Their introduction has been known to reduce EOF. Hitherto, a proper study on the effect of nanostructures orientation on EOF in a microfluidic channel is yet to be carried out. In this investigation, we present a novel fabrication method for nanostructure designs that possess maximum orientation difference, i.e. parallel versus perpendicular indented nanolines, to examine the effect of nanostructures orientation on EOF. It consists of four phases: fabrication of silicon master, creation of mold insert via electroplating, injection molding with cyclic olefin copolymer, and thermal bonding and integration of practical inlet/outlet ports. The effect of nanostructures orientation on EOF was studied experimentally by current monitoring method. The experimental results show that nanolines which are perpendicular to the microchannel reduce the EOF velocity significantly (approximately 20%). This flow velocity reduction is due to the distortion of local electric field by the perpendicular nanolines at the nanostructured surface as demonstrated by finite element simulation. In contrast, nanolines which are parallel to the microchannel have no effect on EOF, as it can be deduced that the parallel nanolines do not distort the local electric field. The outcomes of this investigation contribute to the precise control of EOF in lab-on-chip devices, and fundamental understanding of EOF in devices which utilize nanostructured surfaces for chemical and biological analyses.

On Relations Between the Ozonosphere and the General Atmospheric Circulation in Tropics

NASA Astrophysics Data System (ADS)

Kuznetsov, G. I.; Kramarova, N. A.

2006-05-01

The main features of temporal and spatial ozone distribution over tropics and their relations with peculiarities of the general atmospheric circulation are obtained using the total ozone data for the tropical region (Ozone Data for the World and TOMS (version 8)). Among the factors influencing ozone regime in tropics the properties of the region, like intertropical convergence zone and a structure of tropical tropopause, and processes such as stratosphere-troposphere exchange, migration of ozone equator, Quasi Biennial Oscillation are analyzed. To investigate the long term variability of tropical ozone detrended and de-seasonalized fields of TOMS observations are analyzed by means of EOF method. The first four EOFs explain about 75% of residual total ozone variability in tropical region. Spatial patterns of EOFs and corresponding time coefficients are closely connected with the Quasi-Biennial Oscillation (EOF-1), the 11-years Solar Cycle (EOF-2), the QBO-annual beat (EOF-3) and with the South Oscillation (EOF-4) correspondingly. The detailed analyses of temporal and spatial distribution of ozone EOF patterns reveals a distinct change of ozone fields to the both sides of equator at 10-15 latitude as well as at the zones of tropical tropopause break. A time delay of ozone QBO phase is observed while moving towards higher latitudes. Some features of the tropical ozone regime manifest themselves in the peculiarities of Antarctic Ozone Anomalies. A time variability of ozone QBO passes three months ahead of the Singapore 30 mbar zonal wind. Obtained relations let us to construct a linear regression model based on EOF decomposition to estimate total ozone monthly means over tropics. This model is successfully applied to predict 30 mbar zonal wind in dependence on tropical ozone behavior.

Variability of the recent climate of eastern Africa

NASA Astrophysics Data System (ADS)

Schreck, Carl J., III; Semazzi, Fredrick H. M.

2004-05-01

The primary objective of this study is to investigate the recent variability of the eastern African climate. The region of interest is also known as the Greater Horn of Africa (GHA), and comprises the countries of Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Rwanda, Somalia, Sudan, Uganda, and Tanzania.The analysis was based primarily on the construction of empirical orthogonal functions (EOFs) of gauge rainfall data and on CPC Merged Analysis of Precipitation (CMAP) data, derived from a combination of rain-gauge observations and satellite estimates. The investigation is based on the period 1961-2001 for the short rains season of eastern Africa of October through to December. The EOF analysis was supplemented by projection of National Centers for Environmental Prediction wind data onto the rainfall eigenmodes to understand the rainfall-circulation relationships. Furthermore, correlation and composite analyses have been performed with the Climatic Research Unit globally averaged surface-temperature time series to explore the potential relationship between the climate of eastern Africa and global warming.The most dominant mode of variability (EOF1) based on CMAP data over eastern Africa corresponds to El Niño-southern oscillation (ENSO) climate variability. It is associated with above-normal rainfall amounts during the short rains throughout the entire region, except for Sudan. The corresponding anomalous low-level circulation is dominated by easterly inflow from the Indian Ocean, and to a lesser extent the Congo tropical rain forest, into the positive rainfall anomaly region that extends across most of eastern Africa. The easterly inflow into eastern Africa is part of diffluent outflow from the maritime continent during the warm ENSO events. The second eastern African EOF (trend mode) is associated with decadal variability. In distinct contrast from the ENSO mode pattern, the trend mode is characterized by positive rainfall anomalies over the northern sector of eastern Africa and opposite conditions over the southern sector. This rainfall trend mode eluded detection in previous studies that did not include recent decades of data, because the signal was still relatively weak. The wind projection onto this mode indicates that the primary flow that feeds the positive anomaly region over the northern part of eastern Africa emanates primarily from the rainfall-deficient southern region of eastern Africa and Sudan. Although we do not assign attribution of the trend mode to global warming (in part because of the relatively short period of analysis), the evidence, based on our results and previous studies, strongly suggests a potential connection.

Cluster analysis of multiple planetary flow regimes

NASA Technical Reports Server (NTRS)

Mo, Kingtse; Ghil, Michael

1987-01-01

A modified cluster analysis method was developed to identify spatial patterns of planetary flow regimes, and to study transitions between them. This method was applied first to a simple deterministic model and second to Northern Hemisphere (NH) 500 mb data. The dynamical model is governed by the fully-nonlinear, equivalent-barotropic vorticity equation on the sphere. Clusters of point in the model's phase space are associated with either a few persistent or with many transient events. Two stationary clusters have patterns similar to unstable stationary model solutions, zonal, or blocked. Transient clusters of wave trains serve as way stations between the stationary ones. For the NH data, cluster analysis was performed in the subspace of the first seven empirical orthogonal functions (EOFs). Stationary clusters are found in the low-frequency band of more than 10 days, and transient clusters in the bandpass frequency window between 2.5 and 6 days. In the low-frequency band three pairs of clusters determine, respectively, EOFs 1, 2, and 3. They exhibit well-known regional features, such as blocking, the Pacific/North American (PNA) pattern and wave trains. Both model and low-pass data show strong bimodality. Clusters in the bandpass window show wave-train patterns in the two jet exit regions. They are related, as in the model, to transitions between stationary clusters.

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes

PubMed Central

Wu, Xiaojian

2017-01-01

Asymmetrically shaped nanopores have been shown to rectify the ionic current flowing through pores in a fashion similar to a p-n junction in a solid-state diode. Such asymmetric nanopores include conical pores in polymeric membranes and pyramidal pores in mica membranes. We review here both theoretical and experimental aspects of this ion current rectification phenomenon. A simple intuitive model for rectification, stemming from previously published more quantitative models, is discussed. We also review experimental results on controlling the extent and sign of rectification. It was shown that ion current rectification produces a related rectification of electroosmotic flow (EOF) through asymmetric pore membranes. We review results that show how to measure and modulate this EOF rectification phenomenon. Finally, EOF rectification led to the development of an electroosmotic pump that works under alternating current (AC), as opposed to the currently available direct current EOF pumps. Experimental results on AC EOF rectification are reviewed, and advantages of using AC to drive EOF are discussed. PMID:29240676

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes.

PubMed

Experton, Juliette; Wu, Xiaojian; Martin, Charles R

2017-12-14

Asymmetrically shaped nanopores have been shown to rectify the ionic current flowing through pores in a fashion similar to a p-n junction in a solid-state diode. Such asymmetric nanopores include conical pores in polymeric membranes and pyramidal pores in mica membranes. We review here both theoretical and experimental aspects of this ion current rectification phenomenon. A simple intuitive model for rectification, stemming from previously published more quantitative models, is discussed. We also review experimental results on controlling the extent and sign of rectification. It was shown that ion current rectification produces a related rectification of electroosmotic flow (EOF) through asymmetric pore membranes. We review results that show how to measure and modulate this EOF rectification phenomenon. Finally, EOF rectification led to the development of an electroosmotic pump that works under alternating current (AC), as opposed to the currently available direct current EOF pumps. Experimental results on AC EOF rectification are reviewed, and advantages of using AC to drive EOF are discussed.

Temporal and spatial variations of sea surface temperature in the East China Sea

NASA Astrophysics Data System (ADS)

Tseng, Chente; Lin, Chiyuan; Chen, Shihchin; Shyu, Chungzen

2000-03-01

Sea surface temperature of the East China Sea (ECS) were analyzed using the NOAA/AVHRR SST images. These satellite images reveal surface features of ECS including mainly the Kuroshio Current, Kuroshio Branch Current, Taiwan Warm Current, China coastal water, Changjiang diluted water and Yellow Sea mixed cold water. The SST of ECS ranges from 27 to 29°C in summer; some cold eddies were found off northeast Taiwan and to the south of Changjiang mouth. SST anomalies at the center of these eddies were about 2-5°C. The strongest front usually occurs in May each year and its temperature gradient is about 5-6°C over a cross-shelf distance of 30 nautical miles. The Yellow Sea mixed cold water also provides a contrast from China Coastal waters shoreward of the 50 m isobath; cross-shore temperature gradient is about 6-8°C over 30 nautical miles. The Kuroshio intrudes into ECS preferably at two locations. The first is off northeast Taiwan; the subsurface water of Kuroshio is upwelled onto the shelf while the main current is deflected seaward. The second site is located at 31°N and 128°E, which is generally considered as the origin of the Tsushima Warm Current. More quantitatively, a 2-year time series of monthly SST images is examined using EOF analysis to determine the spatial and temporal variations in the northwestern portion of ECS. The first spatial EOF mode accounts for 47.4% of total spatial variance and reveals the Changjiang plume and coastal cold waters off China. The second and third EOF modes account for 16.4 and 9.6% of total variance, respectively, and their eigenvector images show the intrusion of Yellow Sea mixed cold waters and the China coastal water. The fourth EOF mode accounts for 5.4% of total variance and reveals cold eddies around Chusan Islands. The temporal variance EOF analysis is less revealing in this study area.

An analytic description of electrodynamic dispersion in free-flow zone electrophoresis.

PubMed

Dutta, Debashis

2015-07-24

The present work analyzes the electrodynamic dispersion of sample streams in a free-flow zone electrophoresis (FFZE) chamber resulting due to partial or complete blockage of electroosmotic flow (EOF) across the channel width by the sidewalls of the conduit. This blockage of EOF has been assumed to generate a pressure-driven backflow in the transverse direction for maintaining flow balance in the system. A parallel-plate based FFZE device with the analyte stream located far away from the channel side regions has been considered to simplify the current analysis. Applying a method-of-moments formulation, an analytic expression was derived for the variance of the sample zone at steady state as a function of its position in the separation chamber under these conditions. It has been shown that the increase in stream broadening due to the electrodynamic dispersion phenomenon is additive to the contributions from molecular diffusion and sample injection, and simply modifies the coefficient for the hydrodynamic dispersion term for a fixed lateral migration distance of the sample stream. Moreover, this dispersion mechanism can dominate the overall spatial variance of analyte zones when a significant fraction of the EOF is blocked by the channel sidewalls. The analysis also shows that analyte streams do not undergo any hydrodynamic broadening due to unwanted pressure-driven cross-flows in an FFZE chamber in the absence of a transverse electric field. The noted results have been validated using Monte Carlo simulations which further demonstrate that while the sample concentration profile at the channel outlet approaches a Gaussian distribution only in FFZE chambers substantially longer than the product of the axial pressure-driven velocity and the characteristic diffusion time in the system, the spatial variance of the exiting analyte stream is well described by the Taylor-Aris dispersion limit even in analysis ducts much shorter than this length scale. Copyright © 2015 Elsevier B.V. All rights reserved.

Simple and Rapid Immobilization of Coating Polymers on Poly(dimethyl siloxane)-glass Hybrid Microchips by a Vacuum-drying Method.

PubMed

Kitagawa, Fumihiko; Nakagawara, Syo; Nukatsuka, Isoshi; Hori, Yusuke; Sueyoshi, Kenji; Otsuka, Koji

2015-01-01

A simple and rapid vacuum-drying modification method was applied to several neutral and charged polymers to obtain coating layers for controlling electroosmotic flow (EOF) and suppressing sample adsorption on poly(dimethyl siloxane) (PDMS)-glass hybrid microchips. In the vacuum-dried poly(vinylpyrrolidone) coating, the electroosmotic mobility (μeo) was suppressed from +2.1 to +0.88 × 10(-4) cm(2)/V·s, and the relative standard deviation (RSD) of μeo was improved from 10.2 to 2.5% relative to the bare microchannel. Among several neutral polymers, poly(vinylalcohol) (PVA) and poly(dimethylacrylamide) coatings gave more suppressed and repeatable EOF with RSDs of less than 2.3%. The vacuum-drying method was also applicable to polyanions and polycations to provide accelerated and inversed EOF, respectively, with acceptable RSDs of less than 4.9%. In the microchip electrophoresis (MCE) analysis of bovine serum albumin (BSA) in the vacuum-dried and thermally-treated PVA coating channel, an almost symmetric peak of BSA was obtained, while in the native microchannel a significantly skewed peak was observed. The results demonstrated that the vacuum-dried polymer coatings were effective to control the EOF, and reduced the surface adsorption of proteins in MCE.

Linear monogamy of entanglement in three-qubit systems

NASA Astrophysics Data System (ADS)

Liu, Feng; Gao, Fei; Wen, Qiao-Yan

2015-11-01

For any three-qubit quantum systems ABC, Oliveira et al. numerically found that both the concurrence and the entanglement of formation (EoF) obey the linear monogamy relations in pure states. They also conjectured that the linear monogamy relations can be saturated when the focus qubit A is maximally entangled with the joint qubits BC. In this work, we prove analytically that both the concurrence and EoF obey linear monogamy relations in an arbitrary three-qubit state. Furthermore, we verify that all three-qubit pure states are maximally entangled in the bipartition A|BC when they saturate the linear monogamy relations. We also study the distribution of the concurrence and EoF. More specifically, when the amount of entanglement between A and B equals to that of A and C, we show that the sum of EoF itself saturates the linear monogamy relation, while the sum of the squared EoF is minimum. Different from EoF, the concurrence and the squared concurrence both saturate the linear monogamy relations when the entanglement between A and B equals to that of A and C.

Linear monogamy of entanglement in three-qubit systems.

PubMed

Liu, Feng; Gao, Fei; Wen, Qiao-Yan

2015-11-16

For any three-qubit quantum systems ABC, Oliveira et al. numerically found that both the concurrence and the entanglement of formation (EoF) obey the linear monogamy relations in pure states. They also conjectured that the linear monogamy relations can be saturated when the focus qubit A is maximally entangled with the joint qubits BC. In this work, we prove analytically that both the concurrence and EoF obey linear monogamy relations in an arbitrary three-qubit state. Furthermore, we verify that all three-qubit pure states are maximally entangled in the bipartition A|BC when they saturate the linear monogamy relations. We also study the distribution of the concurrence and EoF. More specifically, when the amount of entanglement between A and B equals to that of A and C, we show that the sum of EoF itself saturates the linear monogamy relation, while the sum of the squared EoF is minimum. Different from EoF, the concurrence and the squared concurrence both saturate the linear monogamy relations when the entanglement between A and B equals to that of A and C.

Linear monogamy of entanglement in three-qubit systems

PubMed Central

Liu, Feng; Gao, Fei; Wen, Qiao-Yan

2015-01-01

For any three-qubit quantum systems ABC, Oliveira et al. numerically found that both the concurrence and the entanglement of formation (EoF) obey the linear monogamy relations in pure states. They also conjectured that the linear monogamy relations can be saturated when the focus qubit A is maximally entangled with the joint qubits BC. In this work, we prove analytically that both the concurrence and EoF obey linear monogamy relations in an arbitrary three-qubit state. Furthermore, we verify that all three-qubit pure states are maximally entangled in the bipartition A|BC when they saturate the linear monogamy relations. We also study the distribution of the concurrence and EoF. More specifically, when the amount of entanglement between A and B equals to that of A and C, we show that the sum of EoF itself saturates the linear monogamy relation, while the sum of the squared EoF is minimum. Different from EoF, the concurrence and the squared concurrence both saturate the linear monogamy relations when the entanglement between A and B equals to that of A and C. PMID:26568265

An Evaluation of Subseasonal Intensity Variation of the South Asian High in the CMIP5 Models

NASA Astrophysics Data System (ADS)

Shang, W.; Ren, X.

2017-12-01

The South Asian High (SAH) is a vital member among the Asian summer monsoon circulations in the upper troposphere located over the Tibetan Plateau and its surrounding areas during boreal summer. This study presents an evaluation of the characteristics of SAH's subseasonal intensity variation simulated by 18 coupled models from the Coupled Model Intercomparison Project (CMIP5). The empirical orthogonal function (EOF) analysis is used on subseasonal anomalies in 100hPa geopotential height over 20°-40°N, 35°-110°E for June, July and August from 1979 to 2005. The first EOF mode from the ERA-Interim (denoted as observation) shows a monopole pattern capturing the strengthening/weakening of SAH. The power spectrum analysis of the corresponding principal component (PC1) time series shows a period about 10-30 days. In general, all the 18 coupled models can reproduce the monopole pattern and its subseasonal oscillation to a certain extent. The four well-simulated models are: ACCESS1-3, HadGEM2-CC, MRI-CGCM3 and BNU-ESM, which EOF1 show strong positive anomalies in the 100hPa geopotential height over the SAH's region and weak negative anomalies in their north side. Lead-lag regression shows that the evolution of the EOF1 from day -12 to +3 in the above four models is also reasonably simulated. In the observation, positive rainfall band moves northward from the equatorial Indian Ocean, the Bay of Bengals and the Western North Pacific to the north of Indian Peninsula, south of Tibetan Plateau and Southeast China, accompanied by the increasing intensity of SAH. In the above four models, the northward movement of anomalous rainfall band can be well reproduced. In the observation, the spatial pattern of anomalies in integrated apparent heat source and integrated apparent moisture sink resemble that of rainfall, thus corresponding to anomalous condensation heat release. The anomalous heating stimulates positive height anomalies with an anomalous anticyclonic circulation to its northwest in the upper troposphere, causing the strengthening of SAH intensity. For the four well-simulated models, the anomalies pattern of and are realistically simulated. That is why they are able to reproduce the key features of the subseasonal intensity variation of the SAH.

The impacts of the atmospheric annular mode on the AMOC and its feedback in an idealized experiment

NASA Astrophysics Data System (ADS)

Santis, Wlademir; Aimola, Luis; Campos, Edmo J. D.; Castellanos, Paola

2018-03-01

The interdecadal variability of the atmospheric and oceanic meridional overturning circulation is studied, using a coupled model with two narrow meridional barriers representing the land and a flat bottomed Aquaplanet. Empirical orthogonal function (EOF) analysis are used in the atmospheric and oceanic meridional overturning cells, revealing the atmospheric interdecadal variability is dominated by an annular mode, in both hemispheres, which introduces in the ocean a set of patterns of variability. The most energetic EOFs in the ocean are the barotropic responses from the annular mode. The interaction between the heat anomalies, due to the barotropic response, and the thermohaline circulation of each basin leads to a resonance mechanism that feeds back to the atmospheric forcing, modulating the annular mode spectrum. Besides the barotropic response, the annular mode introduces anomalies of salinity and temperature in the subtropical Atlantic that affects its upper buoyancy. These anomalies are incorporated within the ocean circulation and advected until the areas of deep sinking in the northern Atlantic, impacting on its overturning circulation as well.

Interannual variation of springtime biomass burning in Indochina: Regional differences, associated atmospheric dynamical changes, and downwind impacts.

PubMed

Huang, Wan-Ru; Wang, Sheng-Hsiang; Yen, Ming-Cheng; Lin, Neng-Huei; Promchote, Parichart

2016-09-16

During March and April, widespread burning occurs across farmlands in Indochina in preparation for planting at the monsoon onset. The resultant aerosols impact the air quality downwind. In this study, we investigate the climatic aspect of the interannual variation of springtime biomass burning in Indochina and its correlation with air quality at Mt. Lulin in Taiwan using long-term (2005-2015) satellite and global reanalysis data. Based on empirical orthogonal function (EOF) analysis, we find that the biomass burning activities vary with two geographical regions: northern Indochina (the primary EOF mode) and southern Indochina (the secondary EOF mode). We determine that the variation of biomass burning over northern Indochina is significantly related with the change in aerosol concentrations at Mt. Lulin. This occurs following the change in the so-called India-Burma Trough in the lower and middle troposphere. When the India-Burma Trough is intensified, a stronger northwesterly wind (to the west of the trough) transports the dryer air from higher latitude into northern Indochina, and this promotes local biomass burning activities. The increase in upward motion to the east of the intensified India-Burma Trough lifts the aerosols, which are transported toward Taiwan by the increased low-level westerly jet. Further diagnoses revealed the connection between the India-Burma Trough and the South Asian jet's wave train pattern as well as the previous winter's El Niño - Southern Oscillation phase. This information highlights the role of the India-Burma Trough in modulating northern Indochina biomass burning and possibly predicting aerosol transport to East Asia on the interannual time scale.

An effective drift correction for dynamical downscaling of decadal global climate predictions

NASA Astrophysics Data System (ADS)

Paeth, Heiko; Li, Jingmin; Pollinger, Felix; Müller, Wolfgang A.; Pohlmann, Holger; Feldmann, Hendrik; Panitz, Hans-Jürgen

2018-04-01

Initialized decadal climate predictions with coupled climate models are often marked by substantial climate drifts that emanate from a mismatch between the climatology of the coupled model system and the data set used for initialization. While such drifts may be easily removed from the prediction system when analyzing individual variables, a major problem prevails for multivariate issues and, especially, when the output of the global prediction system shall be used for dynamical downscaling. In this study, we present a statistical approach to remove climate drifts in a multivariate context and demonstrate the effect of this drift correction on regional climate model simulations over the Euro-Atlantic sector. The statistical approach is based on an empirical orthogonal function (EOF) analysis adapted to a very large data matrix. The climate drift emerges as a dramatic cooling trend in North Atlantic sea surface temperatures (SSTs) and is captured by the leading EOF of the multivariate output from the global prediction system, accounting for 7.7% of total variability. The SST cooling pattern also imposes drifts in various atmospheric variables and levels. The removal of the first EOF effectuates the drift correction while retaining other components of intra-annual, inter-annual and decadal variability. In the regional climate model, the multivariate drift correction of the input data removes the cooling trends in most western European land regions and systematically reduces the discrepancy between the output of the regional climate model and observational data. In contrast, removing the drift only in the SST field from the global model has hardly any positive effect on the regional climate model.

Numerical Analysis of Storm Surge and Seiche at Tokyo Bay caused by the 2 Similar Typhoons, Typhoon Phanphon and Vongfong in 2014

NASA Astrophysics Data System (ADS)

Iwamoto, T.; Takagawa, T.

2017-12-01

A long period damped oscillation, or seiche, sometimes happens inside a harbor after passing typhoon. For some cases, a maximum sea level is observed due to the superposition of astronomical tide and seiche rather than a peak of storm surge. Hence to clarify seiche factors for reducing disaster potential is important, a long-period seiche with a fundamental period of 5.46 hours in Tokyo Bay (Konishi, 2008) was investigated through numerical simulations and analyses. We examined the case of Typhoon Phanphon and Vongfong in 2014 (Hereafter Case P and V). The intensity and moving velocity were similar and the best-tracks were an arc-shaped, typical one approaching to Tokyo Bay. The track of Case V was about 1.5 degree higher latitude than that of Case P, only Typhoon Phanphon caused significant seiche.Firstly, numerical simulations for the 2 storm surges at Tokyo Bay were conducted by Regional Ocean Modeling System (ROMS) and Meso-Scale Model Grid Point Values (MSM-GPV). MSM-GPV gave the 10m wind speed and Sea Level Pressure (SLP), especially the Mean Error (ME) and Root Mean Squire Error (RMSE) of SLP were low compared to the 12 JMA observation points data (Case P: ME -0.303hPa, RMSE 1.87hPa, Case V: ME -0.285hPa, RMSE 0.74hPa). The computational results showed that the maximum of storm surge was underestimated but the difference was less than 20cm at 5 observation points in Tokyo Bay(Fig.1, 2).Then, power spectrals, coherences and phase differences of storm surges at the 5 observation points were obtained by spectral analysis of observed and simulated waveforms. For Case P, the phase-difference between the bay mouth and innermost part of Tokyo Bay was little, and coherence was almost 1(Fig.3, 4). However, for Case V, coherence was small around the fundamental period of 5.46 hours. Furthermore, Empirical Orthogonal Function (EOF) analysis of storm surge, SLP and sea surface stress were conducted. The contributions of EOF1 were above 90% for the all variables, the gradient of storm surge EOF1 was parallel to the bay axis for Case P, but about 50-degree oblique from the axis for Case V(Fig.5, 6). In addition, the EOF1 of SLP for Case P showed a concentric circle structure above Tokyo Bay, besides the structure was not appeared for Case V.

Signal-Processing Algorithm Development for the ACLAIM Sensor

NASA Technical Reports Server (NTRS)

vonLaven, Scott

1995-01-01

Methods for further minimizing the risk by making use of previous lidar observations were investigated. EOFs are likely to play an important role in these methods, and a procedure for extracting EOFs from data has been implemented, The new processing methods involving EOFs could range from extrapolation, as discussed, to more complicated statistical procedures for maintaining low unstart risk.

Surfactant-induced electroosmotic flow in microfluidic capillaries.

PubMed

Azadi, Glareh; Tripathi, Anubhav

2012-07-01

Control of EOF in microfluidic devices is essential in applications such as protein/DNA sizing and high-throughput drug screening. With the growing popularity of poly(methyl methacrylate) (PMMA) as the substrate for polymeric-based microfludics, it is important to understand the effect of surfactants on EOF in these devices. In this article, we present an extensive investigation exploring changes in EOF rate induced by SDS, polyoxyethylene lauryl ether (Brij35) and CTAB in PMMA microfluidic capillaries. In a standard protein buffer (Tris-Glycine), PMMA capillaries exhibited a cathodic EOF with measured mobility of 1.54 ± 0.1 (× 10⁻⁴ cm²/V.s). In the presence of surfactant below a critical concentration, EOF was independent of surfactant concentration. At high concentrations of surfactants, the electroosmotic mobility was found to linearly increase/decrease as the logarithm of concentration before reaching a constant value. With SDS, the EOF increased by 257% (compared to buffer), while it was decreased by 238% with CTAB. In the case of Brij35, the electroosmotic mobility was reduced by 70%. In a binary surfactant system of SDS/CTAB and SDS/Brij35, addition of oppositely charged CTAB reduced the SDS-induced EOF more effectively compared to nonionic Brij35. We propose possible mechanisms that explain the observed changes in EOF and zeta potential values. Use of neutral polymer coatings in combination with SDS resulted in 50% reduction in the electroosmotic mobility with 0.1% hydroxypropyl methyl cellulose (HPMC), while including 2% poly (N,N-dimethylacrylamide) (PDMA) had no effect. These results will potentially contribute to the development of PMMA-based microfluidic devices. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Propagating and Non-propagating Annular Modes and Principal Oscillation Patterns

NASA Astrophysics Data System (ADS)

Plumb, R. A.; Sheshadri, A.

2016-12-01

The leading "annular mode" in each hemisphere — usually defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability — appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. (AM2 explains a significant amount of variance, though less than AM1.) Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing (or weakening and broadening) of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the poleward propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. The leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes poleward propagating anomalies. This mode then shows up as AM1 and AM2 in EOF analyses. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. In the propagating regime, these facts have implications for the use of autocorrelations and cross-correlations to quantify eddy feedback and the susceptibility of the mode to external perturbations, including the response to stratospheric anomalies.

Effect of Divalent Electrolytes on Electroosmotic Flow

NASA Astrophysics Data System (ADS)

Li, Haifeng; Gnanaprakasam, Pradeep

2005-11-01

Electroosmotic flow (EOF) is of importance in micro- and nanofluidic applications. Recent numerical results [Zheng et al. (2003) Electrophoresis 24, 3006] suggest that the addition of even trace amounts of divalent counterions can greatly affect the velocity and electric potential distribution for EOF of a nominally monovalent electrolyte solution, nearly halving the flow rate in 20 nm channels. Scaled experiments were therefore carried out for steady and fully-developed EOF of buffered aqueous mono- and divalent electrolyte mixtures through fused silica microchannels. Nano-particle image velocimetry (nPIV), based upon evanescent-wave illumination of colloidal tracers, was used to obtain velocity data within about 300 nm of the wall. In all cases, the thickness of the electric double layer, defined as the distance from the wall where the velocity and electric potential recover to 99% of their freestream values, is of O(10 nm), or much less than the channel dimension of O(10 μm). The nPIV results are compared with predictions from an asymptotic perturbation analysis.

Alternating current electroosmotic flow in polyelectrolyte-grafted nanochannel.

PubMed

Li, Fengqin; Jian, Yongjun; Chang, Long; Zhao, Guangpu; Yang, Liangui

2016-11-01

In this work, we investigate the time periodic electroosmotic flow (EOF) of an electrolyte solution through a slit polyelectrolyte-grafted (PE-grafted) nanochannel under applied alternating current (AC) electrical field. The PE-grafted nanochannel is represented by a rigid surface covered by a polyelectrolyte layer (PEL) in a brush-like configuration. Under Debye-Hückel approximation, we obtain analytical solutions of electrical potential in decoupled regime of PE-grafted nanochannel, where the thickness of PEL is independent of the electrostatic effects triggered by polyelectrolyte charges. Based upon the electrical potential obtained above, we calculate EOF velocities with uniform and non-uniform drag coefficients for PE-grafted nanochannel and compare their results. The effects of pertinent dimensionless parameters on EOF velocity amplitude are discussed in detail. Moreover, the amplitude of EOF velocity in a PE-grafted nanochannel is compared with that in a rigid one. It is shown that larger EOF velocity and volume flow rate are found for a PE-grafted nanochannel. In addition, AC EOF velocity is further investigated. The oscillation of velocity reduces and is restricted within the region near the PEL-electrolyte interface for higher oscillating Reynolds number Re. Copyright © 2016 Elsevier B.V. All rights reserved.

A two-step method for rapid characterization of electroosmotic flows in capillary electrophoresis.

PubMed

Zhang, Wenjing; He, Muyi; Yuan, Tao; Xu, Wei

2017-12-01

The measurement of electroosmotic flow (EOF) is important in a capillary electrophoresis (CE) experiment in terms of performance optimization and stability improvement. Although several methods exist, there are demanding needs to accurately characterize ultra-low electroosmotic flow rates (EOF rates), such as in coated capillaries used in protein separations. In this work, a new method, called the two-step method, was developed to accurately and rapidly measure EOF rates in a capillary, especially for measuring the ultra-low EOF rates in coated capillaries. In this two-step method, the EOF rates were calculated by measuring the migration time difference of a neutral marker in two consecutive experiments, in which a pressure driven was introduced to accelerate the migration and the DC voltage was reversed to switch the EOF direction. Uncoated capillaries were first characterized by both this two-step method and a conventional method to confirm the validity of this new method. Then this new method was applied in the study of coated capillaries. Results show that this new method is not only fast in speed, but also better in accuracy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

NASA Astrophysics Data System (ADS)

Hu, Zhan; van der Wal, Daphne; Cai, Huayang; van Belzen, Jim; Bouma, Tjeerd J.

2018-06-01

Dynamic equilibrium theory (DET) has been applied to tidal flats to systematically explain intertidal morphological responses to various distributions of bed shear stress (BSS). However, it is difficult to verify this theory with field observations because of the discrepancy between the idealized conceptions of theory and the complex reality of intertidal dynamics. The core relation between intertidal morphodynamics and BSS distribution can be easily masked by noise in complex datasets, leading to conclusions of insufficient field evidence to support DET. In the current study, hydrodynamic and morphodynamic data were monitored daily for one year on two tidal flats with contrasting wave exposures. BSS distribution was obtained by validated numerical models. Tidal flat dynamic equilibrium behaviour and BSS were linked via Empirical Orthogonal Function (EOF) analysis. We show that the principal morphodynamic modes corresponded well with the respective modes of BSS found at both sites. Tide-induced BSS was the dominant force at both sites, regardless of the level of wave exposure. The overall erosional and steepening trend found at the two flats can be attributed to the prevailing action of tidal forcing and reduced sediment supply. Hence, EOF analysis confirmed that tidal flat morphodynamics are consistent with DET, providing both field and model evidence to support this theory.

Estimates of surface humidity and latent heat fluxes over oceans from SSM/I data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, S.H.; Atlas, R.M.; Shie, C.L.

1995-08-01

Monthly averages of daily latent heat fluxes over the oceans for February and August 1988 are estimated using a stability-dependent bulk scheme. Daily fluxes are computed from daily SSM/I (Special Sensor Microwave/Imager) wind speeds and EOF-retrieved SSM/I surface humidity, National Meteorological Center sea surface temperatures, and the European Centre for Medium-Range Weather Forecasts analyzed 2-m temperatures. Daily surface specific humidity (Q) is estimated from SSM/I precipitable water of total (W) and a 500-m bottom layer (W{sub B}) using an EOF (empirical orthogonal function) method. This method has six W-based categories of EOFs (independent of geographical locations) and is developed usingmore » 23 177 FGGE IIb humidity soundings over the global oceans. For 1200 FGGE IIb humidity soundings, the accuracy of EOF-retrieved Q is 0.75 g kg{sup -1} for the case without errors in W and W{sub B} and increases to 1.16 g kg{sup -1} for the case with errors in W and W{sub B}. Compared to 342 collocated radiosonde observations, the EOF-retrieved SSM/I Q has an accuracy of 1.7 g kg{sup -1}. The method improves upon the humidity retrieval of Liu and is competitive with that of Schulz et al. The SSM/I surface humidity and latent heat fluxes of these two months agree reasonably well with those of COADS (Comprehensive Ocean-Atmosphere Data Set). Compared to the COADS, the sea-air humidity difference of SSM/I has a positive bias of approximately 1-3 g kg{sup -1} (an overestimation of flux) over the wintertime eastern equatorial Pacific Ocean, it has a negative bias of about 1-2 g kg{sup -1} (an underestimation of flux). The results further suggest that the two monthly flux estimates, computed from daily and monthly mean data, do not differ significantly over the oceans. 35 refs., 12 figs., 4 tabs.« less

Trends in the Zonal Winds over the Southern Ocean from the NCEP/NCAR Reanalysis and Scatterometers

NASA Astrophysics Data System (ADS)

Richman, J. G.

2002-12-01

The winds over the Southern Ocean for the entire 54-year (1948-2001) period of the NCEP/NCAR Reanalysis have been decomposed into Principal Components (Empirical Orthogonal Functions). The first EOF describes 83 percent of the variance in the zonal wind. The loading of the EOF shows the predominately westerly surface flow with strongest winds in the Indian sector of the Southern Ocean. The structure of this EOF is similar to the Southern Annular Mode (SAM) identified by Thompson, et al 2000. The amplitude of this EOF reveals a large trend of 4.42 cm/s/yr in the strength of the zonal wind corresponding to a nearly 50 percent increase in the wind stress over the Southern Ocean. Such a trend, if real, would be important in the dynamics of the Antarctic Circumpolar Current (ACC). Recent studies by Gille, et al. (2001), Olbers and Ivchenko (2001) and Gent et al. (2001) have shown that the transport of the ACC is correlated to the variability in the zonal wind with a monotonic increase in the transport with increasing zonal wind strength. However, errors in the data assimilation scheme for surface pressure observations on the Antarctic continent appears to have caused a spurious trend in the sea level pressure south of 40S of -0.2 hPa/yr (Hines, et al. 2000 and Marshall, 2002). The sea level pressure difference between 40S and 60S has risen by 8 hPa over the same period. This sea level pressure difference is used as a proxy for the strength of the zonal winds. Thus, the trend in the zonal wind EOF amplitude may be an artifact of model errors in the NCEP Reanalysis. To check this trend, we analyzed scatterometer winds over the Southern Ocean from the SEASAT, ERS (1 and 2), NSCAT and QuikScat satellites. The scatterometer data is not used in the NCEP Reanalysis and, thus, is an independent estimate of the winds. The SEASAT Scatterometer (SASS) operated for 90 days in July-September, 1978, while the ERS, NSCAT and QuikScat scatterometers provide a continuous dataset from September 1992 through the present. The zonal winds for the combined ERS/NSCAT dataset were decomposed into Principal Components, similar to the NCEP winds. The first EOF describes 78 percent of the variance in the zonal wind. The loading of the EOF is nearly identical in structure to the loading of the NCEP EOF, and the correlation between the amplitudes is 0.93 for the coincident period. The trend in the scatterometer winds is 3.9 cm/s/yr for the eight years, which is not significantly different from the 4.4 cm /s/yr trend of the NCEP winds. The three months of SASS data were projected onto the scatterometer EOF and the amplitudes compared to the long-term NCEP amplitudes. The agreement between the scatterometer amplitudes and the NCEP is remarkable. The comparison between the scatterometer winds and NCEP Reanalysis winds suggests that the trend towards increasing zonal winds is real. The increasing zonal winds over the Southern Ocean may lead to a substantial increase in the transport of the ACC over the past 50 years.

Gap-filling meteorological variables with Empirical Orthogonal Functions

NASA Astrophysics Data System (ADS)

Graf, Alexander

2017-04-01

Gap-filling or modelling surface-atmosphere fluxes critically depends on an, ideally continuous, availability of their meteorological driver variables, such as e.g. air temperature, humidity, radiation, wind speed and precipitation. Unlike for eddy-covariance-based fluxes, data gaps are not unavoidable for these measurements. Nevertheless, missing or erroneous data can occur in practice due to instrument or power failures, disturbance, and temporary sensor or station dismounting for e.g. agricultural management or maintenance. If stations with similar measurements are available nearby, using their data for imputation (i.e. estimating missing data) either directly, after an elevation correction or via linear regression, is usually preferred over linear interpolation or monthly mean diurnal cycles. The popular implementation of regional networks of (partly low-cost) stations increases both, the need and the potential, for such neighbour-based imputation methods. For repeated satellite imagery, Beckers and Rixen (2003) suggested an imputation method based on empirical orthogonal functions (EOFs). While exploiting the same linear relations between time series at different observation points as regression, it is able to use information from all observation points to simultaneously estimate missing data at all observation points, provided that never all observations are missing at the same time. Briefly, the method uses the ability of the first few EOFs of a data matrix to reconstruct a noise-reduced version of this matrix; iterating missing data points from an initial guess (the column-wise averages) to an optimal version determined by cross-validation. The poster presents and discusses lessons learned from adapting and applying this methodology to station data. Several years of 10-minute averages of air temperature, pressure and humidity, incoming shortwave, longwave and photosynthetically active radiation, wind speed and precipitation, measured by a regional (70 km by 20 km by 650 m elevation difference) network of 18 sites, were treated by various modifications of the method. The performance per variable and as a function of methodology, such as e.g. number of used EOFs and method to determine its optimum, period length and data transformation, is assessed by cross-validation. Beckers, J.-M., Rixen, M. (2003): EOF calculations and data filling from incomplete oceanographic datasets. J. Atmos. Ocean. Tech. 20, 1839-1856.

Fluid mechanics of electroosmotic flow and its effect on band broadening in capillary electrophoresis.

PubMed

Ghosal, Sandip

2004-01-01

Electroosmotic flow (EOF) usually accompanies electrophoretic migration of charged species in capillary electrophoresis unless special precautions are taken to suppress it. The presence of the EOF provides certain advantages in separations. It is an alternative to mechanical pumps, which are inefficient and difficult to build at small scales, for transporting reagents and analytes on microfluidic chips. The downside is that any imperfection that distorts the EOF profile reduces the separation efficiency. In this paper, the basic facts about EOF are reviewed from the perspective of fluid mechanics and its effect on separations in free solution capillary zone electrophoresis is discussed in the light of recent advances.

A handy liquid metal based electroosmotic flow pump.

PubMed

Gao, Meng; Gui, Lin

2014-06-07

A room temperature liquid metal based electroosmotic flow (EOF) pump has been proposed in this work. This low-cost EOF pump is convenient for both fabrication and integration. It utilizes polydimethylsiloxane (PDMS) microchannels filled with the liquid-metal as non-contact pump electrodes. The electrode channels are fabricated symmetrically to both sides of the pumping channel, having no contact with the pumping channel. To test the pumping performance of the EOF pump, the mean flow velocities of the fluid (DI water) in the EOF pumps were experimentally measured by tracing the fluorescent microparticles in the flow. To provide guidance for designing a low voltage EOF pump, parametric studies on dimensions of the electrode and pumping channels were performed in this work. According to the experimental results, the pumping speed can reach 5.93 μm s(-1) at a driving voltage of only 1.6 V, when the gap between the electrode and the pumping channel is 20 μm. Injecting a room temperature liquid metal into microchannels can provide a simple, rapid, low-cost but accurately self-aligned way to fabricate microelectrodes for EOF pumps, which is a promising method to achieve the miniaturization and integration of the EOF pump in microfluidic systems. The non-contact liquid electrodes have no influence on the fluid in the pumping channel when pumping, reducing Joule heat generation and preventing gas bubble formation at the surface of electrodes. The pump has great potential to drive a wide range of fluids, such as drug reagents, cell suspensions and biological macromolecule solutions.

Interdecadal variability in pan-Pacific and global SST, revisited

NASA Astrophysics Data System (ADS)

Tung, Ka-Kit; Chen, Xianyao; Zhou, Jiansong; Li, King-Fai

2018-05-01

Interest in the "Interdecadal Pacific Oscillation (IPO)" in the global SST has surged recently on suggestions that the Pacific may be the source of prominent interdecadal variations observed in the global-mean surface temperature possibly through the mechanism of low-frequency modulation of the interannual El Nino-Southern Oscillation (ENSO) phenomenon. IPO was defined by performing empirical orthogonal function (EOF) analysis of low-pass filtered SST. The low-pass filtering creates its unique set of mathematical problems—in particular, mode mixing—and has led to some questions, many unanswered. To understand what these EOFs are, we express them first in terms of the recently developed pairwise rotated EOFs of the unfiltered SST, which can largely separate the high and low frequency bands without resorting to filtering. As reported elsewhere, the leading rotated dynamical modes (after the global warming trend) of the unfiltered global SST are: ENSO, Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). IPO is not among them. The leading principal component (PC) of the low-pass filtered global SST is usually defined as IPO and it is seen to comprise of ENSO, PDO and AMO in various proportions depending on the filter threshold. With decadal filtering, the contribution of the interannual ENSO is understandably negligible. The leading dynamical mode of the filtered global SST is mostly AMO, and therefore should not have been called the Interdecadal "Pacific" Oscillation. The leading dynamical mode of the filtered pan-Pacific SST is mostly PDO. This and other low-frequency variability that have the action center in the Pacific, from either the pan-Pacific or global SST, have near zero global mean.

Diagnosis of extratropical variability in seasonal integrations of the ECMWF model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferranti, L.; Molteni, F.; Brankovic, C.

1994-06-01

Properties of the general circulation simulated by the ECMWF model are discussed using a set of seasonal integrations at T63 resolution. For each season, over the period of 5 years, 1986-1990, three integrations initiated on consecutive days were run with prescribed observed sea surface temperature (SST). This paper presents a series of diagnostics of extratropical variability in the model, with particular emphasis on the northern winter. Time-filtered maps of variability indicate that in this season there is insufficient storm track activity penetrating into the Eurasian continent. Related to this the maximum of lower-frequency variability for northern spring are more realistic.more » Blocking is defined objectively in terms of the geostrophic wind at 500 mb. Consistent with the low-frequency transience, in the Euro-Atlantic sector the position of maximum blocking in the model is displaced eastward. The composite structure of blocks over the Pacific is realistic, though their frequency is severely underestimated at all times of year. Shortcomings in the simulated wintertime general circulation were also revealed by studying the projection of 5-day mean fields onto empirical orthogonal functions (EOFs) of the observed flow. The largest differences were apparent for statistics of EOFs of the zonal mean flow. Analysis of weather regime activity, defined from the EOFs, suggested that regimes with positive PNA index were overpopulated, while the negative PNA regimes were underpopulated. A further comparison between observed and modeled low-frequency variance revealed that underestimation of low-frequency variability occurs along the same axes that explain most of the spatial structure of the error in the mean field, suggesting a common dynamical origin for these two aspects of the systematic error. 17 refs., 17 figs., 4 tabs.« less

Sub-weekly to interannual variability of a high-energy shoreline

USGS Publications Warehouse

Barnard, Patrick L.; Jeff E. Hansen,

2010-01-01

Sixty-one Global Positioning System (GPS), sub-aerial beach surveys were completed at 7 km long Ocean Beach, San Francisco, CA (USA), between April 2004 and March 2009. The five-year time series contains over 1 million beach elevation measurements and documents detailed changes in beach morphology over a variety of spatial, temporal, and physical forcing scales. Results show that seasonal processes dominate at Ocean Beach, with the seasonal increase and decrease in wave height being the primary driver of shoreline change. Storm events, while capable of causing large short-term changes in the shoreline, did not singularly account for a large percentage of the overall observed change. Empirical orthogonal function (EOF) analysis shows that the first two modes account for approximately three-quarters of the variance in the data set and are represented by the seasonal onshore/offshore movement of sediment (60%) and the multi-year trend of shoreline rotation (14%). The longer-term trend of shoreline rotation appears to be related to larger-scale bathymetric change. An EOF-based decomposition technique is developed that is capable of estimating the shoreline position to within one standard deviation of the range of shoreline positions observed at most locations along the beach. The foundation of the model is the observed relationship between the temporal amplitudes of the first EOF mode and seasonally-averaged offshore wave height as well as the linear trend of shoreline rotation. This technique, while not truly predictive because of the requirement of real-time wave data, is useful because it can predict shoreline position to within reasonable confidence given the absence of field data once the model is developed at a particular site.

Sub-weekly to interannual variability of a high-energy shoreline

USGS Publications Warehouse

Hansen, J.E.; Barnard, P.L.

2010-01-01

Sixty-one Global Positioning System (GPS), sub-aerial beach surveys were completed at 7 km long Ocean Beach, San Francisco, CA (USA), between April 2004 and March 2009. The five-year time series contains over 1. million beach elevation measurements and documents detailed changes in beach morphology over a variety of spatial, temporal, and physical forcing scales. Results show that seasonal processes dominate at Ocean Beach, with the seasonal increase and decrease in wave height being the primary driver of shoreline change. Storm events, while capable of causing large short-term changes in the shoreline, did not singularly account for a large percentage of the overall observed change. Empirical orthogonal function (EOF) analysis shows that the first two modes account for approximately three-quarters of the variance in the data set and are represented by the seasonal onshore/offshore movement of sediment (60%) and the multi-year trend of shoreline rotation (14%). The longer-term trend of shoreline rotation appears to be related to larger-scale bathymetric change. An EOF-based decomposition technique is developed that is capable of estimating the shoreline position to within one standard deviation of the range of shoreline positions observed at most locations along the beach. The foundation of the model is the observed relationship between the temporal amplitudes of the first EOF mode and seasonally-averaged offshore wave height as well as the linear trend of shoreline rotation. This technique, while not truly predictive because of the requirement of real-time wave data, is useful because it can predict shoreline position to within reasonable confidence given the absence of field data once the model is developed at a particular site. ?? 2010 Elsevier B.V.

Monitoring the spatio-temporal changes of terrestrial water storage using GRACE data in the Tarim River basin between 2002 and 2015.

PubMed

Yang, Peng; Xia, Jun; Zhan, Chesheng; Qiao, Yunfeng; Wang, Yueling

2017-10-01

With the threat of water shortages intensifying, the need to identify the terrestrial water storage (TWS) variation in the Tarim River Basin (TRB) becomes very significant for managing its water resource. Due to the lack of large-scale hydrological data, this study employed the Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) to monitor TWS variation in the TRB during the period of 2002-2015, cooperating with two statistical techniques, Principal Component Analysis (PCA) - Empirical Orthogonal Function (EOF) and Multiple Linear Regression (MLR). Results indicated that (1) the Tropical rainfall measuring mission (TRMM) data can be applied well in the TRB; (2) the EOF result showed that both the time series of TRMM precipitation and GRACE-derived TWS in the TRB between 2002 and 2015 were dominated by the annual signals, which were followed by the semiannual signals; (3) the linear trend for the spatially averaged GRACE-derived TWS changes exhibited an decrease of 1.6±1.1mm/a, and the EOF result indicated a significant decrease of 4.1±1.5mm/a in the north of TRB; (4) while the precipitation variations was the major driver for the TWS changes, the GLDAS-derived TWS (i.e., soil moisture) decrease and ground water decrease played the major role in the TWS decrease in the north of TRB for the significant correlation (P<0.05). The changes of TWS might be linked to excessive exploitation of water resources, increased population, and shrinking water supplies, which would impact on the water level of the lakes or reservoir. Copyright © 2017 Elsevier B.V. All rights reserved.

High pH instability of quaternary ammonium surfactant coatings in capillary electrophoresis.

PubMed

Shulman, Lisa; Pei, Lei; Bahnasy, Mahmoud F; Lucy, Charles A

2017-06-12

The two-tailed cationic surfactant dioctadecyldimethyl ammonium bromide (DODAB) produces semi-permanent coatings that yield strongly reversed electroosmotic flow (EOF), for example -0.31 ± 0.01 cm 2 kV -1 s -1 at pH 3.5. Moreover, these coatings are easy to prepare, regenerable, cost effective, and yield high efficiency (520 000-900 000 plates per m) separations of cationic proteins over many runs under acidic (pH 3.5) conditions. Given the quaternary amine functionality of DODAB, we were surprised to observe that DODAB coatings become unstable at pH > 7. At pH 7.2, the EOF of a DODAB coated capillary drifted from reversed to cathodic over only 5 runs, and protein separations became severely compromised. By pH 12, no EOF reversal was observed. Electrophoretic and mass spectrometric studies demonstrate that the coating decomposition involves a surface conversion of the quaternary amine in DODAB to a variety of products, although the exact mechanism remains elusive. Regardless, the results herein demonstrate that semi-permanent coatings based on cationic two-tailed surfactants such as DODAB are limited to separations using acidic buffers.

North-South precipitation patterns in western North America on interannual-to-decadal timescales

USGS Publications Warehouse

Dettinger, M.D.; Cayan, D.R.; Diaz, Henry F.; Meko, D.M.

1998-01-01

The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25??to 55??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both timescales, two leading EOFs describe 1) a north-south seesaw of precipitation pivoting near 40??N and 2) variations in precipitation near 40??N, respectively. The amount of overall precipitation variability is only about 10% of the mean and is largely determined by precipitation variations around 40??-45??N and most consistently influenced by nearby circulation patterns; in this sense, domain-average precipitation is closely related to the second EOF. The central latitude and latitudinal spread of precipitation distributions are strongly influenced by precipitation variations in the southern parts of western North America and are closely related to the first EOF. Central latitude of precipitation moves south (north) with tropical warming (cooling) in association with midlatitude western Pacific SLP variations, on both interannual and decadal timescales. Regional patterns and zonal averages of precipitation-sensitive tree-ring series are used to corroborate these patterns and to extend them into the past and appear to share much long- and short-term information with the instrumentally based zonal precipitation EOFs and moments.The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25?? to 55 ??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both tim

20th century trends of drought conditions in the Mediterranean: the influence of large-scale circulation patterns.

NASA Astrophysics Data System (ADS)

Sousa, Pedro; Trigo, Ricardo; Garcia-Herrera, Ricardo

2010-05-01

Here we have used the Self Calibrated PDSI (scPDSI) proposed by Wells et al (2004) as a more appropriate approach to characterize drought conditions in the Mediterranean area. The scPDSI has been shown to perform better (than the original PDSI) when evaluating spatial and temporal drought characteristics for regions outside the USA (Schrier et al, 2005). Seasonal and annual trends for the 1901-2000, 1901-1950 and 1951-2000 periods were computed using the standard Mann-Kendall test for trend significance evaluation. However, statistical significance obtained with this test can be highly misleading because it does not take into account the low variability nature that dominates the seasonal evolution of scPDSI fields. We have now improved these results by employing a modified Mann-Kendall test for auto-correlated series (Hamed and Ramachandra, 1997), such as the scPDSI case. This development allowed for a better definition of the Mediterranean areas characterized by significant changes in the scPDSI, namely the largely negative trends that dominate the Mediterranean basin, with the exceptions of parts of eastern Turkey and northwestern Iberia, since initially these areas were overestimated. The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. Afterwards we perform a comprehensive analysis on the links between the scPDSI and the large-scale atmospheric circulation indices that affect the Mediterranean basin, namely; NAO, EA, and SCAND (Trigo et al., 2006) and where we have also taken into account once again the effect of autocorrelation. Some of these links were obtained with 3 or 6 months lagged relationships, while others were achieved with instantaneous (no lag) links. This analysis was performed for the entire Mediterranean region as a whole, but also for each considered sub-domain. Finally, a stepwise regression model was developed to reproduce summer scPDSI series during the 1951-2002 period, using these large scale indices as predictors in the model. This procedure results in positive Skill Score values against the persistence model. Hamed K.H., Ramachandra A. (1997) "A modified Mann-Kendall trend test for autocorrelated data", Journal of Hidrology, 204, 182-196. Schrier G, Briffa KR, Jones PD, Osborn TJ. (2005). Summer moisture variability across Europe. Journal of Climate 19: 2818-2834. Trigo, R. and 21 authors (2006) Relations between variability in the Mediterranean region and mid-latitude variability. In: P. Lionello, P. Malanotte-Rizzoli & R. Boscolo (Eds), Mediterranean Climate Variability, Amsterdam: Elsevier, pp. 179-226. Wells N, Goddard S and Hayes MJ (2004) A self-calibrating Palmer Drought Severity Index. Journal of Climate 17, 2335-2351.

Rotation of EOFs by the Independent Component Analysis: Towards A Solution of the Mixing Problem in the Decomposition of Geophysical Time Series

NASA Technical Reports Server (NTRS)

Aires, Filipe; Rossow, William B.; Chedin, Alain; Hansen, James E. (Technical Monitor)

2001-01-01

The Independent Component Analysis is a recently developed technique for component extraction. This new method requires the statistical independence of the extracted components, a stronger constraint that uses higher-order statistics, instead of the classical decorrelation, a weaker constraint that uses only second-order statistics. This technique has been used recently for the analysis of geophysical time series with the goal of investigating the causes of variability in observed data (i.e. exploratory approach). We demonstrate with a data simulation experiment that, if initialized with a Principal Component Analysis, the Independent Component Analysis performs a rotation of the classical PCA (or EOF) solution. This rotation uses no localization criterion like other Rotation Techniques (RT), only the global generalization of decorrelation by statistical independence is used. This rotation of the PCA solution seems to be able to solve the tendency of PCA to mix several physical phenomena, even when the signal is just their linear sum.

Spatiotemporal Variability of the Meteorological Drought in Romania using the Standardized Precipitation Index

NASA Astrophysics Data System (ADS)

Cheval, Sorin; Busuioc, Aristita; Dumitrescu, Alexandru; Birsan, Marius-Victor

2013-04-01

Drought events occur over any geographical area, and may impact severely the environment and society. In terms of economic losses, droughts are one of the major natural hazards affecting Romania, so that the topic has been constantly approached. In general, the climatic projections over the 21st century display increasing temperatures and very likely declining summer precipitation (Busuioc et al., 2010), probably causing better drought conditions. This study examines the variability of the droughts in Romania, aiming to characterize the droughts intensity, durations and frequency (a), to identify spatial and temporal patterns (b), trends (c), and potential triggering factors (d). Besides, we consider comparing the performance of different instances of the Standardized Precipitation Index (SPI) (McKee et al., 1993), such as time scale and probability distribution functions (gamma and Pearson type III), for retrieving drought characteristics. Homogenous monthly precipitation amounts from 98 weather stations run by the Romanian Meteorological Administration covering the period 1961-2010 were the primary data for calculating 1, 3, 6, and 12-month time scale SPI. The Mann-Kendall statistics sustained the trend significance examination, while Empirical Orthogonal Function (EOF) analysis synthesizes the climate signal related to spatial and temporal characteristics of variability over Romania. The SPI variability over Romania is mainly influenced by the large-scale mechanisms (e.g. North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO)) accounting for more than 50% from the observed variance, on second place being the Carpathians accounting for the highest influence in winter (11%). Thus, the Carpathians separate Romania in two major regions in terms of drought characteristics, namely outside and inside the mountainous arch. Significant trends towards dry conditions are noted at very few stations in winter, spring and summer, while trend to precipitation surplus cover extended areas in autumn. Further, preliminary analysis has demonstrated that NAO and AMO influence the characteristics of the meteorological drought over Romania, and qualify as possible predictors in water deficit studies. However, a stronger connection was found between the time series associated to SPI EOF1 and sea level pressure EOF1 over the region 5°E-45°E, 30°N-55°N. The work has been financed by the research project Changes in climate extremes and associated impact in hydrological events in Romania (CLIMHYDEX), Cod PN II-ID-2011-2-0073, sponsored by the National Authority for Scientific Research.

Satellite imagery in the fight against Malaria, the case for Genetic Programming

NASA Astrophysics Data System (ADS)

Ssentongo, J. S.; Hines, E. L.

The analysis of multi-temporal data is a critical issue in the field of remote sensing and presents a constant challenge The approach used here relies primarily on utilising a method commonly used in statistics and signal processing Empirical Orthogonal Function EOF analysis Normalized Difference Vegetation Index NDVI and Rainfall Estimate RFE satellite images pertaining to the Sub-Saharan Africa region were obtained The images are derived from the Advanced Very High Resolution Radiometer AVHRR on the United States National Oceanic and Atmospheric Administration NOAA polar orbiting satellites spanning from January 2000 to December 2002 The region of interest was narrowed down to the Limpopo Province Northern Province of South Africa EOF analyses of the space-time-intensity series of dekadal mean NDVI values was been performed They reveal that NDVI can be accurately approximated by its principal component time series and contains a near sinusoidal oscillation pattern Peak greenness essentially what NDVI measures seasons last approximately 8 weeks This oscillation period is very similar to that of Malaria cases reported in the same period but lags behind by 4 dekads about 40 days Singular Value Decomposition SVD of Coupled Fields is performed on the spacetime-intensity series of dekadal mean NDVI and RFE values Correlation analyses indicate that both Malaria and greenness appear to be dependant on rainfall the onset of their seasonal highs always following an arrival of rain There is a greater

On the Predictability of Northeast Monsoon Rainfall over South Peninsular India in General Circulation Models

NASA Astrophysics Data System (ADS)

Nair, Archana; Acharya, Nachiketa; Singh, Ankita; Mohanty, U. C.; Panda, T. C.

2013-11-01

In this study the predictability of northeast monsoon (Oct-Nov-Dec) rainfall over peninsular India by eight general circulation model (GCM) outputs was analyzed. These GCM outputs (forecasts for the whole season issued in September) were compared with high-resolution observed gridded rainfall data obtained from the India Meteorological Department for the period 1982-2010. Rainfall, interannual variability (IAV), correlation coefficients, and index of agreement were examined for the outputs of eight GCMs and compared with observation. It was found that the models are able to reproduce rainfall and IAV to different extents. The predictive power of GCMs was also judged by determining the signal-to-noise ratio and the external error variance; it was noted that the predictive power of the models was usually very low. To examine dominant modes of interannual variability, empirical orthogonal function (EOF) analysis was also conducted. EOF analysis of the models revealed they were capable of representing the observed precipitation variability to some extent. The teleconnection between the sea surface temperature (SST) and northeast monsoon rainfall was also investigated and results suggest that during OND the SST over the equatorial Indian Ocean, the Bay of Bengal, the central Pacific Ocean (over Nino3 region), and the north and south Atlantic Ocean enhances northeast monsoon rainfall. This observed phenomenon is only predicted by the CCM3v6 model.

Characters of Vertical Variability with Geodetic Satellites and Ground-based Continuous GPS in Taiwan

NASA Astrophysics Data System (ADS)

Yang, C.-C.; Wu, Y.-H.; Chao, B. F.; Yu, S.-B.

2009-04-01

Present-day GPS network have been extensively used to monitor crustal deformation due to various geodynamic mechanisms. Situated among the Pacific Ring of Fire on the suture zone of Eurasian and Philippine Sea Plates, the island of Taiwan with a dense continuous GPS network since ~1996 and now over 300 stations sees plenty of geophysical phenomena including particularly prominent crustal motions. We assessed daily solution of each station's coordinate time series, and made the routine corrections, such as orbital, EOP, atmospheric and tidal corrections, using GAMIT/GLOBK software (with ITRF05). We then employ the Quasi-Observation Combination Analysis (QOCA) package to obtain the variability and trend after removing occasional earthquake "disruptions". Preliminary results show strong seasonal variations. We then utilize the numerical method of Empirical Orthogonal Function (EOF) to analysis the geophysical signals from the continuous and dense GPS vertical crustal motion observations. We wish to be able to characterize both the seasonal and non-seasonal variability in the vertical crustal motion, in terms of the EOF modes in the spatial domain over Taiwan (plus a few offshore islets) with time evolution spanning the entire period of time. Corraborating with time-variable gravity data from the geodetic satellite mission GRACE, we can further obtain vertical components of both mass-induced loading with respect to the precipitation minus evaporation and the crustal motion caused by the active tectonic processes on Taiwan.

Variations in freshwater pathways from the Arctic Ocean into the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Wang, Zeliang; Hamilton, James; Su, Jie

2017-06-01

Understanding the mechanisms that drive exchanges between the Arctic Ocean and adjacent oceans is critical to building our knowledge of how the Arctic is reacting to a warming climate, and how potential changes in Arctic Ocean freshwater export may impact the AMOC (Atlantic Meridional Overturning Circulation). Here, freshwater pathways from the Arctic Ocean to the North Atlantic are investigated using a 1 degree global model. An EOF analysis of modeled sea surface height (SSH) demonstrates that while the second mode accounts for only 15% of the variability, the associated geostrophic currents are strongly correlated with freshwater exports through CAA (Canadian Arctic Archipelago; r = 0.75), Nares Strait (r = 0.77) and Fram Strait (r = -0.60). Separation of sea level into contributing parts allows us to show that the EOF1 is primarily a barotropic mode reflecting variability in bottom pressure equivalent sea level, while the EOF2 mode reflects changes in steric height in the Arctic Basin. This second mode is linked to momentum wind driven surface current, and dominates the Arctic Ocean freshwater exports. Both the Arctic Oscillation and Arctic Dipole atmospheric indices are shown to be linked to Arctic Ocean freshwater exports, with the forcing associated with the Arctic Dipole reflecting the out-of-phase relationship between transports through the CAA and those through Fram Strait. Finally, observed freshwater transport variation through the CAA is found to be strongly correlated with tide gauge data from the Beaufort Sea coast (r = 0.81), and with the EOF2 mode of GRACE bottom pressure data (r = 0.85) on inter-annual timescales.

A global weighted mean temperature model based on empirical orthogonal function analysis

NASA Astrophysics Data System (ADS)

Li, Qinzheng; Chen, Peng; Sun, Langlang; Ma, Xiaping

2018-03-01

A global empirical orthogonal function (EOF) model of the tropospheric weighted mean temperature called GEOFM_Tm was developed using high-precision Global Geodetic Observing System (GGOS) Atmosphere Tm data during the years 2008-2014. Due to the quick convergence of EOF decomposition, it is possible to use the first four EOF series, which consists base functions Uk and associated coefficients Pk, to represent 99.99% of the overall variance of the original data sets and its spatial-temporal variations. Results show that U1 displays a prominent latitude distribution profile with positive peaks located at low latitude region. U2 manifests an asymmetric pattern that positive values occurred over 30° in the Northern Hemisphere, and negative values were observed at other regions. U3 and U4 displayed significant anomalies in Tibet and North America, respectively. Annual variation is the major component of the first and second associated coefficients P1 and P2, whereas P3 and P4 mainly reflects both annual and semi-annual variation components. Furthermore, the performance of constructed GEOFM_Tm was validated by comparison with GTm_III and GTm_N with different kinds of data including GGOS Atmosphere Tm data in 2015 and radiosonde data from Integrated Global Radiosonde Archive (IGRA) in 2014. Generally speaking, GEOFM_Tm can achieve the same accuracy and reliability as GTm_III and GTm_N models in a global scale, even has improved in the Antarctic and Greenland regions. The MAE and RMS of GEOFM_Tm tend to be 2.49 K and 3.14 K with respect to GGOS Tm data, respectively; and 3.38 K and 4.23 K with respect to IGRA sounding data, respectively. In addition, those three models have higher precision at low latitude than middle and high latitude regions. The magnitude of Tm remains at the range of 220-300 K, presented a high correlation with geographic latitude. In the Northern Hemisphere, there was a significant enhancement at high latitude region reaching 270 K during summer. GEOFM_Tm is capable to represent the spatiotemporal variations of Tm, with the high accuracy and reliability in a global scale, therefore, will be of great significance to the real-time GNSS water vapor inversion and climate studies.

Variation of Antarctic circumpolar current and its intensification in relation to the southern annular mode detected in the time-variable gravity signals by GRACE satellite

NASA Astrophysics Data System (ADS)

Liau, Jen-Ru; Chao, Benjamin F.

2017-07-01

The southern annular mode (SAM) in the atmosphere and the Antarctic circumpolar current (ACC) in the ocean play decisive roles in the climatic system of the mid- to high-latitude southern hemisphere. Using the time-variable gravity data from the GRACE satellite mission, we find the link between the space-time variabilities of the ACC and the SAM. We calculate the empirical orthogonal functions (EOF) of the non-seasonal ocean bottom pressure (OBP) field in the circum-Antarctic seas from the GRACE data for the period from 2003 to 2015. We find that the leading EOF mode of the non-seasonal OBP represents a unison OBP oscillation around Antarctica with time history closely in pace with that of the SAM Index with a high correlation of 0.77. This OBP variation gives rise to a variation in the geostrophic flow field; the result for the same EOF mode shows heightened variations in the zonal velocity that resides primarily in the eastern hemispheric portion of the ACC and coincided geographically with the southernmost boundary of the ACC's main stream. Confirming previous oceanographic studies, these geodetic satellite results provide independent information toward better understanding of the ACC-SAM process.

Recent climate extremes associated with the West Pacific Warming Mode

USGS Publications Warehouse

Funk, Chris; Hoell, Andrew

2017-01-01

Here we analyze empirical orthogonal functions (EOFs) of observations and a 30 member ensemble of Community Earth System Model version 1 (CESM1) simulations, and suggest that precipitation declines in the Greater Horn of Africa (GHA) and the northern Middle East/Southwestern Asia (NME/SWE: Iran, Iraq, Kuwait, Syria, Saudi Arabia north of 25°N, Israel, Jordan, and Lebanon) may be interpreted as an interaction between La Niña-like decadal variability and the West Pacific Warming Mode (WPWM). While they exhibit different SST patterns, warming of the Pacific cold tongue (ENSO) and warming of the western Pacific (WPWM) produce similar warm pool diabatic forcing, Walker circulation anomalies, and terrestrial teleconnections. CESM1 SST EOFs indicate that both La Niña-like WPWM warming and El Niño-like east Pacific warming will be produced by climate change. The temporal frequency of these changes, however, are distinct. WPWM varies decadally, while ENSO is dominated by interannual variability. Future WPWM and ENSO warming may manifest as a tendency toward warm West Pacific SST, punctuated by extreme warm East Pacific events. WPWM EOFs from Global Precipitation Climatology Project (GPCP) precipitation also identify dramatic WPWM-related declines in the Greater Horn of Africa and NME/SWE.

A suite of global reconstructed precipitation products and their error estimate by multivariate regression using empirical orthogonal functions: 1850-present

NASA Astrophysics Data System (ADS)

Shen, S. S.

2014-12-01

This presentation describes a suite of global precipitation products reconstructed by a multivariate regression method using an empirical orthogonal function (EOF) expansion. The sampling errors of the reconstruction are estimated for each product datum entry. The maximum temporal coverage is 1850-present and the spatial coverage is quasi-global (75S, 75N). The temporal resolution ranges from 5-day, monthly, to seasonal and annual. The Global Precipitation Climatology Project (GPCP) precipitation data from 1979-2008 are used to calculate the EOFs. The Global Historical Climatology Network (GHCN) gridded data are used to calculate the regression coefficients for reconstructions. The sampling errors of the reconstruction are analyzed in detail for different EOF modes. Our reconstructed 1900-2011 time series of the global average annual precipitation shows a 0.024 (mm/day)/100a trend, which is very close to the trend derived from the mean of 25 models of the CMIP5 (Coupled Model Intercomparison Project Phase 5). Our reconstruction examples of 1983 El Niño precipitation and 1917 La Niña precipitation (Figure 1) demonstrate that the El Niño and La Niña precipitation patterns are well reflected in the first two EOFs. The validation of our reconstruction results with GPCP makes it possible to use the reconstruction as the benchmark data for climate models. This will help the climate modeling community to improve model precipitation mechanisms and reduce the systematic difference between observed global precipitation, which hovers at around 2.7 mm/day for reconstructions and GPCP, and model precipitations, which have a range of 2.6-3.3 mm/day for CMIP5. Our precipitation products are publically available online, including digital data, precipitation animations, computer codes, readme files, and the user manual. This work is a joint effort between San Diego State University (Sam Shen, Nancy Tafolla, Barbara Sperberg, and Melanie Thorn) and University of Maryland (Phil Arkin, Tom Smith, Li Ren, and Li Dai) and supported in part by the U.S. National Science Foundation (Awards No. AGS-1015926 and AGS-1015957).

Mechanisms for Seasonal and Interannual Sea Surface Salinity Variability in the Indian Ocean

NASA Astrophysics Data System (ADS)

Köhler, J.; Stammer, D.; Serra, N.; Bryan, F.

2016-12-01

Space-borne salinity data in the Indian Ocean are analyzed over the period 2000-2015 based on data from the European Space Agency's (ESA) "Soil Moisture and Ocean Salinity" (SMOS) and the National Aeronautical Space Agency's (NASA) "Aquarius/SAC-D" missions. The seasonal variability is the dominant mode of sea surface salinity (SSS) variability in the Indian Ocean, accounting for more than 50% of salinity variance. Through a combined analysis of the satellite and ARGO data, dominant forcing terms for seasonal salinity changes are identified. It is found, that E-P controls seasonal salinity tendency in the western Indian Ocean, where the ITCZ has a strong seasonal cycle. In contrast, Ekman advection is the dominant term in the northern and eastern equatorial Indian Ocean. The influence of vertical processes on the salinity tendency is enhanced in coastal upwelling regions and south of the equator due to mid-ocean upwelling. Jointly those processes can explain most of the observed seasonal cycle with a correlation of 0.85 and an RMS difference of 0.07/month. However, the detailed composition of driving terms depends on underlying data products. In general, our study confirms previous results from Lisan Yu (2011); however, in the eastern Indian Ocean contrasting results indicate the leading role of meridional Ekman advection to the seasonal salinity tendency instead of surface external forces due to precipitation. The inferred dominant salinity budget terms are confirmed by results obtained from a high resolution NCAR Core model run driven by NCEP forcing fields. From an EOF analysis of the salinity fields after substracting the annual and semiannual cycle we found that the first EOF mode explains more than 20% of salinity variance. The first principal component of SSS EOF is correlated with the Indian Ocean Dipole Mode Index. Nevertheless the EOF pattern shows a meridional tripole structure, while the IOD describes a zonal SST dipole (Saji et al, 1999).

Electroosmotic Flow Rectification in Membranes with Asymmetrically Shaped Pores: Effects of Current and Pore Density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, Gregory W.; Lopez, Marcos M.; Ramiah Rajasekaran, Pradeep

2015-07-09

We have recently demonstrated a new electrokinetic phenomenon—electroosmotic flow rectification in membranes with asymmetrically shaped pores. Flow rectification means that at constant driving force the flow rate in one direction through the membrane is faster than the flow rate in the opposite direction. EOF rectification could be of practical use in microfluidic devices incorporating porous membranes, but additional research is required. We explore here the effects of two key experimental variables—current density used to drive flow through the membrane and membrane pore density—on EOF rectification. We have found that the extent of EOF rectification, as quantified by the rectification ratio,more » increases with increasing current density. In contrast, the rectification ratio decreases with increasing membrane pore density. We propose explanations for these results based on simple EOF and membrane-transport theories.« less

Hemispheric Circulation Regimes Associated with Predominant Anomaly Patterns of Wintertime Temperature Distribution over the Far East

NASA Astrophysics Data System (ADS)

Mukougawa, H.; Mabuchi, M.

2012-04-01

Characteristics of extratropical planetary flow regimes in the Northern Hemisphere associated with prevailing spatial patterns of temperature anomaly distribution in the winter season (DJF) over the Far East are examined based on 2D phase space spanned by the leading two EOFs of the Far East low-frequency temperature variation by the use of ERA-40 reanalysis dataset from 1957/58 to 2001/02 winter and NOAA OLR dataset from 1979/80 to 2001/02 winter. The first EOF of 10-day low-pass filtered 850-hPa temperature anomaly in the winter season over the Far East (25˚N-50˚N, 120˚E-150˚E) represents a coherent temperature variation over the whole domain while the second EOF corresponds to a meridional dipole pattern with a node around 40˚N. These two leading EOFs explain 76% of the total temperature variance over the Far East. Regression analysis of 250-hPa height anomaly with respect to the corresponding PCs shows that EOF1 and EOF2 are related to the Eurasian (EU) and the West Pacific (WP) pattern, respectively. The PDF of 850-hPa low-frequency temperature anomaly is estimated by the kernel density estimation method of Kimoto and Ghil (1993) in 2D phase space spanned by the leading 2 PCs. Inhomogeneity of the observed PDF from the bivariate Gaussianity is evaluated by a nonparametric method, and we find the existence of two distinct regimes with significantly greater PDF than the Gaussianity: One regime (regime A) represents an atmospheric state with low temperature anomaly over the whole Far East region, especially over Western Japan. The other regime (regime B) corresponds to a state with a prevailing weak positive temperature anomaly over the Far East. Finally, a composite analysis of 250-hPa height anomaly associated with regime A based on the 2D phase space reveals its time evolution as follows: Blocking developing over the Alaska 15 days (day -15) before the mature phase of regime A has a retrograde phase velocity and resides over the Sea of Okhotsk. After day -10, the EU pattern emanating from cyclonic anomaly over Europe creates a cyclonic anomaly over Western Japan and an anticyclonic anomaly over East Siberia. The anticyclonic anomaly is also amplified through the superposition of the retrograding blocking. Then, regime A comprising the EU pattern and the WP pattern with a dominant negative height anomaly over Western Japan causes a strong cold surge in Southeast Asia. Moreover, the analysis on the OLR dataset reveals that an upper-tropospheric Rossby wave train emanating from the Bay of Bengal due to an anomalous convective activity over the South China Sea also plays an important role in forming the cyclonic anomaly over Western Japan. We will discuss the recent high occurrence probability of regime A in connection with the warming trend of the SST over the western Pacific due to the global warming.

Representation of the equatorial stratospheric quasi-biennial oscillation in EOF phase space. [EOF (empirical orthogonal function)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, J.M.; Panetta, R.L.; Estberg, J.

1993-06-15

A 35-year record of monthly mean zonal wind data for the equatorial stratosphere is represented in terms of a vector (radius and phase angle) in a two-dimensional phase space defined by the normalized expansion coefficients of the two leading empirical orthogonal functions (EOFs) of the vertical structure. The tip of the vector completes one nearly circular loop during each cycle of the quasi-biennial oscillation (QBO). Hence, its position and rate of progress along the orbit of the point provide a measure of the instantaneous amplitude and rate of phase progression of the QBO. Although the phase of the QBO bearsmore » little if any relation to calendar month, the rate of phase progression is strongly modulated by the first and second harmonics of the annual cycle, with a primary maximum in April/May, in agreement with previous studies based on the descent rates of easterly and westerly regimes. A simple linear prediction model is developed for the rate of phase progression, based on the phase of the QBO and the phase of the annual cycle. The model is capable of hindcasting the phase of the QBO to within a specified degree of accuracy approximately 50% longer than a default scheme based on the mean observed rate of phase progression of the QBO (1 cycle per 28.1 months). If the seasonal dependence is ignored, the prediction equation corresponds to the [open quotes]circle map,[close quotes] for which an extensive literature exists in dynamical systems theory. 17 refs., 14 figs., 2 tabs.« less

Topside correction of IRI by global modeling of ionospheric scale height using COSMIC radio occultation data

NASA Astrophysics Data System (ADS)

Wu, M. J.; Guo, P.; Fu, N. F.; Xu, T. L.; Xu, X. S.; Jin, H. L.; Hu, X. G.

2016-06-01

The ionosphere scale height is one of the most significant ionospheric parameters, which contains information about the ion and electron temperatures and dynamics in upper ionosphere. In this paper, an empirical orthogonal function (EOF) analysis method is applied to process all the ionospheric radio occultations of GPS/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) from the year 2007 to 2011 to reconstruct a global ionospheric scale height model. This monthly medium model has spatial resolution of 5° in geomagnetic latitude (-87.5° ~ 87.5°) and temporal resolution of 2 h in local time. EOF analysis preserves the characteristics of scale height quite well in the geomagnetic latitudinal, anural, seasonal, and diurnal variations. In comparison with COSMIC measurements of the year of 2012, the reconstructed model indicates a reasonable accuracy. In order to improve the topside model of International Reference Ionosphere (IRI), we attempted to adopt the scale height model in the Bent topside model by applying a scale factor q as an additional constraint. With the factor q functioning in the exponent profile of topside ionosphere, the IRI scale height should be forced equal to the precise COSMIC measurements. In this way, the IRI topside profile can be improved to get closer to the realistic density profiles. Internal quality check of this approach is carried out by comparing COSMIC realistic measurements and IRI with or without correction, respectively. In general, the initial IRI model overestimates the topside electron density to some extent, and with the correction introduced by COSMIC scale height model, the deviation of vertical total electron content (VTEC) between them is reduced. Furthermore, independent validation with Global Ionospheric Maps VTEC implies a reasonable improvement in the IRI VTEC with the topside model correction.

Spatial and temporal variability of Mediterranean drought events

NASA Astrophysics Data System (ADS)

Trigo, R.; Sousa, P.; Nieto, R.; Gimeno, L.

2009-04-01

The original Palmer Drought Severity Index (PDSI) and a recent adaptation to European soil characteristics, the Self Calibrated PDSI (or scPDSI) proposed by Schrier et al (2005) were used. We have computed monthly, seasonal and annual trends between 1901 and 2000 but also for the first and second halves of the 20th century. Results were represented only when achieving a minimum level of statistical significance (either 5% or 10% using a Mann-Kendall test) and confirm that the majority of the western and central Mediterranean is getting drier in the last decades of the 20th century while Turkey is generally getting wetter (Trigo et al., 2006). The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. The inter-annual variability of the regional spatial droughts indices for each region was analyzed separately. We have also performed an evaluation of their eventual links with large-scale atmospheric circulation indices that affect the Mediterranean basin, namely the NAO, EA, and SCAND. Finally we have evaluated the main sources of moisture affecting two drought prone areas in the western (Iberia) and eastern (Balkans) Mediterranean. This analysis was performed by means of backward tracking the air masses that ultimately reach these two regions using the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998) and meteorological analysis data from the ECMWF to track atmospheric moisture. This was done for a five-year period (2000-2004) and using ECMWF operational analysis available every six hours (00, 06, 12 and 18 UTC) with a 1°x1° resolution (Sthol et al., 2004). Following the approach used by the authors for the Sahel (Nieto et al., 2006) and Tropical south America (Nieto et al., 2008) we traced (E-P) backwards from both regions, limiting the transport times to 10 days, which is the average time that water vapor resides in the atmosphere. In order to evaluate possible shifts in the origin of the moisture sources (between wet and dry years) this analysis was performed independently for dry and wet winter seasons. Nieto R., Gimeno L., Trigo R.M. (2006) A Lagrangian identification of major sources of Sahel moisture. Geophys. Res. Letters, 33, L18707, doi:10.1029/2006GL027232. Nieto R., Ribera P., Trigo R.M. , Gallego D., Gimeno L.(2008) Dynamic identification of moisture sources in the Orinoco Basin. Hydrological Sciences Journal, 53, 602-612. Schrier G, Briffa KR, Jones PD, Osborn TJ. (2005). Summer moisture variability across Europe. Journal of Climate, 19, 2818-2834. Stohl, A., M. Hittenberger, and G. Wotawa (1998), Validation of the Lagrangian particle dispersion model FLEXPART against large scale tracer experiment data, Atmos. Environ., 32, 4245- 4264. Stohl, A., and P. James (2004), A Lagrangian analysis of the atmospheric branch of the global water cycle. Part 1: Method description, validation, and demonstration for the August 2002 flooding in central Europe. J. Hydrometeor., 5, 656-678. Trigo, R. and 21 authors (2006) Relations between variability in the Mediterranean region and mid-latitude variability. In: P. Lionello, P. Malanotte-Rizzoli & R. Boscolo (Eds), Mediterranean Climate Variability, Amsterdam: Elsevier, pp. 179-226.

Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

NASA Astrophysics Data System (ADS)

Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

2017-06-01

In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

Matrix partitioning and EOF/principal component analysis of Antarctic Sea ice brightness temperatures

NASA Technical Reports Server (NTRS)

Murray, C. W., Jr.; Mueller, J. L.; Zwally, H. J.

1984-01-01

A field of measured anomalies of some physical variable relative to their time averages, is partitioned in either the space domain or the time domain. Eigenvectors and corresponding principal components of the smaller dimensioned covariance matrices associated with the partitioned data sets are calculated independently, then joined to approximate the eigenstructure of the larger covariance matrix associated with the unpartitioned data set. The accuracy of the approximation (fraction of the total variance in the field) and the magnitudes of the largest eigenvalues from the partitioned covariance matrices together determine the number of local EOF's and principal components to be joined by any particular level. The space-time distribution of Nimbus-5 ESMR sea ice measurement is analyzed.

Use of a mixture of n-dodecyl-beta-D-maltoside and sodium dodecyl sulfate in poly(dimethylsiloxane) microchips to suppress adhesion and promote separation of proteins.

PubMed

Huang, Bo; Kim, Samuel; Wu, Hongkai; Zare, Richard N

2007-12-01

Dynamic modification of poly(dimethylsiloxane) channels using a mixture of n-dodecyl-beta-D-maltoside (DDM) and sodium dodecyl sulfate (SDS) is able to suppress analyte adsorption and control electroosmotic flow (EOF). In this mixed surfactant system, the nonionic surfactant DDM functions as a surface blocking reagent, whereas the anionic surfactant SDS introduces negative charges to the channel walls. Changing the DDM/SDS mixing ratio tunes the surface charge density and the strength of EOF. Using 0.1% (w/v) DDM and 0.03% (w/v) SDS, Alexa Fluor 647 labeled streptavidin can be analyzed according to the charges added by the fluorophores. Protein molecules with different numbers of fluorophores are well resolved. DDM and SDS also form negatively charged mixed micelles, which act as a separation medium. The low critical micellar concentration of DDM/SDS mixed micelles also allows the use of SDS at a nondenaturing concentration, which enables the analysis of proteins in their native state. The immunocomplex between a membrane protein, beta2 adrenergic receptor, and anti-FLAG antibody has been fully separated using 0.1% (w/v) DDM and 0.03% (w/v) SDS. We have also analyzed the composition of light-harvesting protein-chromophore complexes in cyanobacteria.

Electroosmotic flows of non-Newtonian power-law fluids in a cylindrical microchannel.

PubMed

Zhao, Cunlu; Yang, Chun

2013-03-01

EOF of non-Newtonian power-law fluids in a cylindrical microchannel is analyzed theoretically. Specially, exact solutions of electroosmotic velocity corresponding to two special fluid behavior indices (n = 0.5 and 1.0) are found, while approximate solutions are derived for arbitrary values of fluid behavior index. It is found that because of the approximation for the first-order modified Bessel function of the first kind, the approximate solutions introduce largest errors for predicting electroosmotic velocity when the thickness of electric double layer is comparable to channel radius, but can accurately predict the electroosmotic velocity when the thickness of electric double layer is much smaller or larger than the channel radius. Importantly, the analysis reveals that the Helmholtz-Smoluchowski velocity of power-law fluids in cylindrical microchannels becomes dependent on geometric dimensions (radius of channel), standing in stark contrast to the Helmholtz-Smoluchowski velocity over planar surfaces or in parallel-plate microchannels. Such interesting and counterintuitive effects can be attributed to the nonlinear coupling among the electrostatics, channel geometry, and non-Newtonian hydrodynamics. Furthermore, a method for enhancement of EOFs of power-law fluids is proposed under a combined DC and AC electric field. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variability of cold season surface air temperature over northeastern China and its linkage with large-scale atmospheric circulations

NASA Astrophysics Data System (ADS)

Zhuang, Yuanhuang; Zhang, Jingyong; Wang, Lin

2018-05-01

Cold temperature anomalies and extremes have profound effects on the society, the economy, and the environment of northeastern China (NEC). In this study, we define the cold season as the months from October to April, and investigate the variability of cold season surface air temperature (CSAT) over NEC and its relationships with large-scale atmospheric circulation patterns for the period 1981-2014. The empirical orthogonal function (EOF) analysis shows that the first EOF mode of the CSAT over NEC is characterized by a homogeneous structure that describes 92.2% of the total variance. The regionally averaged CSAT over NEC is closely linked with the Arctic Oscillation ( r = 0.62, 99% confidence level) and also has a statistically significant relation with the Polar/Eurasian pattern in the cold season. The positive phases of the Arctic Oscillation and the Polar/Eurasian pattern tend to result in a positive geopotential height anomaly over NEC and a weakened East Asian winter monsoon, which subsequently increase the CSAT over NEC by enhancing the downward solar radiation, strengthening the subsidence warming and warm air advection. Conversely, the negative phases of these two climate indices result in opposite regional atmospheric circulation anomalies and decrease the CSAT over NEC.

Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements

NASA Astrophysics Data System (ADS)

Wilhelmsen, Hallgeir; Ladstädter, Florian; Scherllin-Pirscher, Barbara; Steiner, Andrea K.

2018-03-01

We provide atmospheric temperature variability indices for the tropical troposphere and stratosphere based on global navigation satellite system (GNSS) radio occultation (RO) temperature measurements. By exploiting the high vertical resolution and the uniform distribution of the GNSS RO temperature soundings we introduce two approaches, both based on an empirical orthogonal function (EOF) analysis. The first method utilizes the whole vertical and horizontal RO temperature field from 30° S to 30° N and from 2 to 35 km altitude. The resulting indices, the leading principal components, resemble the well-known patterns of the Quasi-Biennial Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO) in the tropics. They provide some information on the vertical structure; however, they are not vertically resolved. The second method applies the EOF analysis on each altitude level separately and the resulting indices contain information on the horizontal variability at each densely available altitude level. They capture more variability than the indices from the first method and present a mixture of all variability modes contributing at the respective altitude level, including the QBO and ENSO. Compared to commonly used variability indices from QBO winds or ENSO sea surface temperature, these new indices cover the vertical details of the atmospheric variability. Using them as proxies for temperature variability is also of advantage because there is no further need to account for response time lags. Atmospheric variability indices as novel products from RO are expected to be of great benefit for studies on atmospheric dynamics and variability, for climate trend analysis, as well as for climate model evaluation.

Propagating annular modes

NASA Astrophysics Data System (ADS)

Sheshadri, A.; Plumb, R. A.

2017-12-01

The leading "annular mode", defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability, appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. In the troposphere, the leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes propagating anomalies. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. These facts have implications for eddy feedback and the susceptibility of the mode to external perturbations. If one interprets the annular modes as the modes of the system, then simple theory predicts that the response to steady forcing will usually be dominated by AM1 (with the longest time scale). However, such arguments should really be applied to the true modes. Experiments with a simplified GCM show that climate response to perturbations do not necessarily have AM1 structures. Implications of these results for stratosphere-troposphere interactions are explored. The POP structures are shown to be independent of any weighting (unlike the EOFs, the structures and time scales of which change substantially with pressure weighting), a fact that is particularly important for a deep system such as the troposphere and stratospere. The structure and time evolution of coupled modes of the troposphere-stratosphere system are studied.

Forecasting ENSO events: A neural network-extended EOF approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tangang, F.T.; Tang, B.; Monahan, A.H.

The authors constructed neural network models to forecast the sea surface temperature anomalies (SSTA) for three regions: Nino 4. Nino 3.5, and Nino 3, representing the western-central, the central, and the eastern-central parts of the equatorial Pacific Ocean, respectively. The inputs were the extended empirical orthogonal functions (EEOF) of the sea level pressure (SLP) field that covered the tropical Indian and Pacific Oceans and evolved for a duration of 1 yr. The EEOFs greatly reduced the size of the neural networks from those of the authors` earlier papers using EOFs. The Nino 4 region appeared to be the best forecastedmore » region, with useful skills up to a year lead time for the 1982-93 forecast period. By network pruning analysis and spectral analysis, four important inputs were identified: modes 1, 2, and 6 of the SLP EEOFs and the SSTA persistence. Mode 1 characterized the low-frequency oscillation (LFO, with 4-5-yr period), and was seen as the typical ENSO signal, while mode 2, with a period of 2-5 yr, characterized the quasi-biennial oscillation (QBO) plus the LFO. Mode 6 was dominated by decadal and interdecadal variations. Thus, forecasting ENSO required information from the QBO, and the decadal-interdecadal oscillations. The nonlinearity of the networks tended to increase with lead time and to become stronger for the eastern regions of the equatorial Pacific Ocean. 35 refs., 14 figs., 4 tabs.« less

Long term, non-anthropogenic groundwater storage changes simulated by a global land surface model

NASA Astrophysics Data System (ADS)

Li, B.; Rodell, M.; Sheffield, J.; Wood, E. F.

2017-12-01

Groundwater is crucial for meeting agricultural, industrial and municipal water needs, especially in arid, semi-arid and drought impacted regions. Yet, knowledge on groundwater response to climate variability is not well understood due to lack of systematic and continuous in situ measurements. In this study, we investigate global non-anthropogenic groundwater storage variations with a land surface model driven by a 67-year (1948-204) meteorological forcing data set. Model estimates were evaluated using in situ groundwater data from the central and northeastern U.S. and terrestrial water storage derived from the Gravity Recovery and Climate Experiment (GRACE) satellites and found to be reasonable. Empirical orthogonal function (EOF) analysis was employed to examine modes of variability of groundwater storage and their relationship with atmospheric effects such as precipitation and evapotranspiration. The result shows that the leading mode in global groundwater storage reflects the influence of the El Niño Southern Oscillation (ENSO). Consistent with the EOF analysis, global total groundwater storage reflected the low frequency variability of ENSO and decreased significantly over 1948-2014 while global ET and precipitation did not exhibit statistically significant trends. This study suggests that while precipitation and ET are the primary drivers of climate related groundwater variability, changes in other forcing fields than precipitation and temperature are also important because of their influence on ET. We discuss the need to improve model physics and to continuously validate model estimates and forcing data for future studies.

A comparison of the gravity field over Central Europe from superconducting gravimeters, GRACE and global hydrological models, using EOF analysis

NASA Astrophysics Data System (ADS)

Crossley, David; de Linage, Caroline; Hinderer, Jacques; Boy, Jean-Paul; Famiglietti, James

2012-05-01

We analyse data from seven superconducting gravimeter (SG) stations in Europe from 2002 to 2007 from the Global Geodynamics Project (GGP) and compare seasonal variations with data from GRACE and several global hydrological models - GLDAS, WGHM and ERA-Interim. Our technique is empirical orthogonal function (EOF) decomposition of the fields that allows for the inherent incompatibility of length scales between ground and satellite observations. GGP stations below the ground surface pose a problem because part of the attraction from soil moisture comes from above the gravimeter, and this gives rise to a complex (mixed) gravity response. The first principle component (PC) of the EOF decomposition is the main indicator for comparing the fields, although for some of the series it accounts for only about 50 per cent of the variance reduction. PCs for GRACE solutions RL04 from CSR and GFZ are filtered with a cosine taper (degrees 20-40) and a Gaussian window (350 km). Significant differences are evident between GRACE solutions from different groups and filters, though they all agree reasonably well with the global hydrological models for the predominantly seasonal signal. We estimate the first PC at 10-d sampling to be accurate to 1 μGal for GGP data, 1.5 μGal for GRACE data and 1 μGal between the three global hydrological models. Within these limits the CNES/GRGS solution and ground GGP data agree at the 79 per cent level, and better when the GGP solution is restricted to the three above-ground stations. The major limitation on the GGP side comes from the water mass distribution surrounding the underground instruments that leads to a complex gravity effect. To solve this we propose a method for correcting the SG residual gravity series for the effects of soil moisture above the station.

The cross wavelet and wavelet coherence analysis of spatio-temporal rainfall-groundwater system in Pingtung plain, Taiwan

NASA Astrophysics Data System (ADS)

Lin, Yuan-Chien; Yu, Hwa-Lung

2013-04-01

The increasing frequency and intensity of extreme rainfall events has been observed recently in Taiwan. Particularly, Typhoon Morakot, Typhoon Fanapi, and Typhoon Megi consecutively brought record-breaking intensity and magnitude of rainfalls to different locations of Taiwan in these two years. However, records show the extreme rainfall events did not elevate the amount of annual rainfall accordingly. Conversely, the increasing frequency of droughts has also been occurring in Taiwan. The challenges have been confronted by governmental agencies and scientific communities to come up with effective adaptation strategies for natural disaster reduction and sustainable environment establishment. Groundwater has long been a reliable water source for a variety of domestic, agricultural, and industrial uses because of its stable quantity and quality. In Taiwan, groundwater accounts for the largest proportion of all water resources for about 40%. This study plans to identify and quantify the nonlinear relationship between precipitation and groundwater recharge, find the non-stationary time-frequency relations between the variations of rainfall and groundwater levels to understand the phase difference of time series. Groundwater level data and over-50-years hourly rainfall records obtained from 20 weather stations in Pingtung Plain, Taiwan has been collected. Extract the space-time pattern by EOF method, which is a decomposition of a signal or data set in terms of orthogonal basis functions determined from the data for both time series and spatial patterns, to identify the important spatial pattern of groundwater recharge and using cross wavelet and wavelet coherence method to identify the relationship between rainfall and groundwater levels. Results show that EOF method can specify the spatial-temporal patterns which represents certain geological characteristics and other mechanisms of groundwater, and the wavelet coherence method can identify general correlation between rainfall and groundwater signal at low frequency and high frequency relationship at some certain extreme rainfall events. Keywords: extreme rainfall, groundwater, EOF, wavelet coherence

Influence of the West Pacific subtropical high on surface ozone daily variability in summertime over eastern China

NASA Astrophysics Data System (ADS)

Zhao, Zijian; Wang, Yuxuan

2017-12-01

The West Pacific subtropical high (WPSH), as one of the most important components of the East Asian summer monsoon (EASM), is the key synoptic-scale circulation pattern influencing summertime precipitation and atmospheric conditions in China. Here we investigate the impacts of the WPSH on surface ozone daily variability over eastern China, using observations from recently established network of ozone monitors and meteorology reanalysis data during summer (June, July, August; JJA) 2014-2016 with a focus on 2014. An empirical orthogonal function (EOF) analysis of daily ozone variations reveals that the dominating eigenvector (EOF1), which contributes a quarter (25.2%) to the total variances, is a marked north-south contrast. This pattern is temporally well correlated (r = -0.66, p < 0.01) with daily anomalies of a normalized WPSH intensity index (WPSH-I). Spatially, the WPSH-I and ozone correlation is positive in North China (NC) but negative in South China (SC), which well correlates with the ozone EOF1 pattern showing the same north-south contrast (r = -0.86, p < 0.01). These associations suggest the dominant component of surface ozone daily variability in eastern China is linked with the variability of the WPSH intensity in that a stronger WPSH leads to a decrease of surface ozone over SC but an increase over NC and vice versa. This is because a stronger WPSH enhances southwesterly transport of moisture into SC, creating such conditions not conducive for ozone formation as higher RH, more cloudiness and precipitation, less UV radiation, and lower temperature. Meanwhile, as most of the rainfall due to the enhanced southwesterly transport of moisture occurs in SC, water vapor is largely depleted in the air masses transported towards NC, creating dry and sunny conditions over NC under a strong WPSH, thereby promoting ozone formation.

Extracting climate signals from large hydrological data cubes using multivariate statistics - an example for the Mediterranean basin

NASA Astrophysics Data System (ADS)

Kauer, Agnes; Dorigo, Wouter; Bauer-Marschallinger, Bernhard

2017-04-01

Global warming is expected to change ocean-atmosphere oscillation patterns, e.g. the El Nino Southern Oscillation, and may thus have a substantial impact on water resources over land. Yet, the link between climate oscillations and terrestrial hydrology has large uncertainties. In particular, the climate in the Mediterranean basin is expected to be sensitive to global warming as it may increase insufficient and irregular water supply and lead to more frequent and intense droughts and heavy precipitation events. The ever increasing need for water in tourism and agriculture reinforce the problem. Therefore, the monitoring and better understanding of the hydrological cycle are crucial for this area. This study seeks to quantify the effect of regional climate modes, e.g. the Northern Atlantic Oscillation (NAO) on the hydrological cycle in the Mediterranean. We apply Empirical Orthogonal Functions (EOF) to a wide range of hydrological datasets to extract the major modes of variation over the study period. We use more than ten datasets describing precipitation, soil moisture, evapotranspiration, and changes in water mass with study periods ranging from one to three decades depending on the dataset. The resulting EOFs are then examined for correlations with regional climate modes using Spearman rank correlation analysis. This is done for the entire time span of the EOFs and for monthly and seasonally sampled data. We find relationships between the hydrological datasets and the climate modes NAO, Arctic Oscillation (AO), Eastern Atlantic (EA), and Tropical Northern Atlantic (TNA). Analyses of monthly and seasonally sampled data reveal high correlations especially in the winter months. However, the spatial extent of the data cube considered for the analyses have a large impact on the results. Our statistical analyses suggest an impact of regional climate modes on the hydrological cycle in the Mediterranean area and may provide valuable input for evaluating process-oriented climate models. The study is supported by WACMOS-MED project of the European Space Agency.

Analytical study of mixed electroosmotic-pressure-driven flow in rectangular micro-channels

NASA Astrophysics Data System (ADS)

Movahed, Saeid; Kamali, Reza; Eghtesad, Mohammad; Khosravifard, Amir

2013-09-01

Operational state of many miniaturized devices deals with flow field in microchannels. Pressure-driven flow (PDF) and electroosmotic flow (EOF) can be recognized as the two most important types of the flow field in such channels. EOF has many advantages in comparison with PDF, such as being vibration free and not requiring any external mechanical pumps or moving parts. However, the disadvantages of this type of flow such as Joule heating, electrophoresis demixing, and not being suitable for mobile devices must be taken into consideration carefully. By using mixed electroosmotic/pressure-driven flow, the role of EOF in producing desired velocity profile will be reduced. In this way, the advantages of EOF can be exploited, and its disadvantages can be prevented. Induced pressure gradient can be utilized in order to control the separation in the system. Furthermore, in many complicated geometries such as T-shape microchannels, turns may induce pressure gradient to the electroosmotic velocity. While analytical formulas are completely essential for analysis and control of any industrial and laboratory microdevices, lack of such formulas in the literature for solving Poisson-Boltzmann equation and predicting electroosmotic velocity field in rectangular domains is evident. In the present study, first a novel method is proposed to solve Poisson-Boltzmann equation (PBE). Subsequently, this solution is utilized to find the electroosmotic and the mixed electroosmotic/pressure-driven velocity profile in a rectangular domain of the microchannels. To demonstrate the accuracy of the presented analytical method in solving PBE and finding electroosmotic velocity, a general nondimensional example is analyzed, and the results are compared with the solution of boundary element method. Additionally, the effects of different nondimensional parameters and also aspect ratio of channels on the electroosmotic part of the flow field will be investigated.

Use of Numerical Groundwater Model and Analytical Empirical Orthogonal Function for Calibrating Spatiotemporal pattern of Pumpage, Recharge and Parameter

NASA Astrophysics Data System (ADS)

Huang, C. L.; Hsu, N. S.; Hsu, F. C.; Liu, H. J.

2016-12-01

This study develops a novel methodology for the spatiotemporal groundwater calibration of mega-quantitative recharge and parameters by coupling a specialized numerical model and analytical empirical orthogonal function (EOF). The actual spatiotemporal patterns of groundwater pumpage are estimated by an originally developed back propagation neural network-based response matrix with the electrical consumption analysis. The spatiotemporal patterns of the recharge from surface water and hydrogeological parameters (i.e. horizontal hydraulic conductivity and vertical leakance) are calibrated by EOF with the simulated error hydrograph of groundwater storage, in order to qualify the multiple error sources and quantify the revised volume. The objective function of the optimization model is minimizing the root mean square error of the simulated storage error percentage across multiple aquifers, meanwhile subject to mass balance of groundwater budget and the governing equation in transient state. The established method was applied on the groundwater system of Chou-Shui River Alluvial Fan. The simulated period is from January 2012 to December 2014. The total numbers of hydraulic conductivity, vertical leakance and recharge from surface water among four aquifers are 126, 96 and 1080, respectively. Results showed that the RMSE during the calibration process was decreased dramatically and can quickly converse within 6th iteration, because of efficient filtration of the transmission induced by the estimated error and recharge across the boundary. Moreover, the average simulated error percentage according to groundwater level corresponding to the calibrated budget variables and parameters of aquifer one is as small as 0.11%. It represent that the developed methodology not only can effectively detect the flow tendency and error source in all aquifers to achieve accurately spatiotemporal calibration, but also can capture the peak and fluctuation of groundwater level in shallow aquifer.

Optimal Design for Placements of Tsunami Observing Systems to Accurately Characterize the Inducing Earthquake

NASA Astrophysics Data System (ADS)

Mulia, Iyan E.; Gusman, Aditya Riadi; Satake, Kenji

2017-12-01

Recently, there are numerous tsunami observation networks deployed in several major tsunamigenic regions. However, guidance on where to optimally place the measurement devices is limited. This study presents a methodological approach to select strategic observation locations for the purpose of tsunami source characterizations, particularly in terms of the fault slip distribution. Initially, we identify favorable locations and determine the initial number of observations. These locations are selected based on extrema of empirical orthogonal function (EOF) spatial modes. To further improve the accuracy, we apply an optimization algorithm called a mesh adaptive direct search to remove redundant measurement locations from the EOF-generated points. We test the proposed approach using multiple hypothetical tsunami sources around the Nankai Trough, Japan. The results suggest that the optimized observation points can produce more accurate fault slip estimates with considerably less number of observations compared to the existing tsunami observation networks.

Patterns of variability in steady- and non steady-state Ross Ice Shelf flow

NASA Astrophysics Data System (ADS)

Campbell, A. J.; Hulbe, C. L.; Scambos, T. A.; Klinger, M. J.; Lee, C. K.

2016-12-01

Ice shelves are gateways through which climate change can be transmitted from the ocean or atmosphere to a grounded ice sheet. It is thus important to separate patterns of ice shelf change driven internally (from the ice sheet) and patterns driven externally (by the ocean or atmosphere) so that modern observations can be viewed in an appropriate context. Here, we focus on the Ross Ice Shelf (RIS), a major component of the West Antarctic Ice Sheet system and a feature known to experience variable ice flux from tributary ice streams and glaciers, for example, ice stream stagnation and glacier surges. We perturb a model of the Ross Ice Shelf with periodic influx variations, ice rise and ice plain grounding events, and iceberg calving in order to generate transients in the ice shelf flow and thickness. Characteristic patterns associated with those perturbations are identified using empirical orthogonal functions (EOFs). The leading EOFs reveal shelf-wide pattern of response to local perturbations that can be interpreted in terms of coupled mass and momentum balance. For example, speed changes on Byrd Glacier cause both thinning and thickening in a broad region that extends to Roosevelt Island. We calculate decay times at various locations for various perturbations and find that mutli-decadal to century time scales are typical. Unique identification of responses to particular forcings may thus be difficlult to achieve and flow divergence cannot be assumed to be constant when interpreting observed changes in ice thickness. In reality, perturbations to the ice shelf do not occur individually, rather the ice shelf contains a history of boundary perturbations. To explore the degree individual perturbations are seperable from their ensemble, EOFs from individual events are combined in pairs and compared against experiments with the same periodic perturbations pairs. Residuals between these EOFs reveal the degree interaction between between disctinct perturbations.

Microchip electrophoresis of oligosaccharides using large-volume sample stacking with an electroosmotic flow pump in a single channel.

PubMed

Kawai, Takayuki; Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

2010-08-01

The applicability of an online preconcentration technique, large-volume sample stacking with an electroosmotic flow pump (LVSEP), to microchip zone electrophoresis (MCZE) for the analysis of oligosaccharides was investigated. Since the sample stacking and separation proceeded continuously without polarity switching in LVSEP, a single "straight" channel microchip could be employed. In the MCZE analysis of oligosaccharides, sample adsorption onto the channel surface should be suppressed, so the straight microchannel was modified with poly(vinyl alcohol) (PVA). So far, the mechanism of LVSEP in the polymer-coated capillary or microchannel has not been reported, and thus, the LVSEP process in the PVA-coated channel was investigated by fluorescence imaging. Although it is well-known that the PVA coating can suppress the electroosmotic flow (EOF), an enhanced EOF with a mobility of 4.4 x 10(-4) cm(2)/(V x s) was observed in a low ionic strength sample solution. It was revealed that such temporarily enhanced EOF in the sample zone worked as the driving force to remove the sample matrix in LVSEP. To evaluate the analytical performance of LVSEP-MCZE, oligosaccharides were analyzed in the PVA-coated straight channel. As a result, both the glucose ladder and oligosaccharides obtained from bovine ribonuclease B were well enriched and separated with up to 2200-2900-fold sensitivity enhancement compared to those in a conventional MCZE analysis. The run-to-run repeatabilities of the migration time and peak height were good with relative standard deviations of 1.1% and 7.2%, respectively, which were better than those of normal MCZE. By applying the LVSEP technique to MCZE, a complicated voltage program for fluidic control could be simplified from four channels for two steps to two channels for one step.

Hydrological signals in height and gravity in northeastern Italy inferred from principal components analysis

NASA Astrophysics Data System (ADS)

Zerbini, S.; Raicich, F.; Richter, B.; Gorini, V.; Errico, M.

2010-04-01

This work describes a study of GPS heights, gravity and hydrological time series collected by stations located in northeastern Italy. During the last 12 years, changes in the long-term behaviors of the GPS heights and gravity time series are observed. In particular, starting in 2004-2005, a height increase is observed over the whole area. The temporal and spatial variability of these parameters has been studied as well as those of key hydrological variables, namely precipitation, hydrological balance and water table by using the Empirical Orthogonal Functions (EOF) analysis. The coupled variability between the GPS heights and the hydrological balance and precipitation data has been investigated by means of the Singular Value Decomposition (SVD) approach. Significant common patterns in the spatial and temporal variability of these parameters have been recognized. In particular, hydrology-induced variations are clearly observable starting in 2002-2003 in the southern part of the Po Plain for the longest time series, and from 2004-2005 over the whole area. These findings, obtained by means of purely mathematical approaches, are supported by sound physical interpretation suggesting that the climate-related fluctuations in the regional/local hydrological regime are one of the main contributors to the observed variations. A regional scale signal has been identified in the GPS station heights; it is characterized by the opposite behavior of the southern and northern stations in response to the hydrological forcing. At Medicina, in the southern Po Plain, the EOF analysis has shown a marked common signal between the GPS heights and the Superconducting Gravimeter (SG) data both over the long and the short period.

A conceptual prediction model for seasonal drought processes using atmospheric and oceanic standardized anomalies: application to regional drought processes in China

NASA Astrophysics Data System (ADS)

Liu, Zhenchen; Lu, Guihua; He, Hai; Wu, Zhiyong; He, Jian

2018-01-01

Reliable drought prediction is fundamental for water resource managers to develop and implement drought mitigation measures. Considering that drought development is closely related to the spatial-temporal evolution of large-scale circulation patterns, we developed a conceptual prediction model of seasonal drought processes based on atmospheric and oceanic standardized anomalies (SAs). Empirical orthogonal function (EOF) analysis is first applied to drought-related SAs at 200 and 500 hPa geopotential height (HGT) and sea surface temperature (SST). Subsequently, SA-based predictors are built based on the spatial pattern of the first EOF modes. This drought prediction model is essentially the synchronous statistical relationship between 90-day-accumulated atmospheric-oceanic SA-based predictors and SPI3 (3-month standardized precipitation index), calibrated using a simple stepwise regression method. Predictor computation is based on forecast atmospheric-oceanic products retrieved from the NCEP Climate Forecast System Version 2 (CFSv2), indicating the lead time of the model depends on that of CFSv2. The model can make seamless drought predictions for operational use after a year-to-year calibration. Model application to four recent severe regional drought processes in China indicates its good performance in predicting seasonal drought development, despite its weakness in predicting drought severity. Overall, the model can be a worthy reference for seasonal water resource management in China.

Summer U.S. Surface Air Temperature Variability: Controlling Factors and AMIP Simulation Biases

NASA Astrophysics Data System (ADS)

Merrifield, A.; Xie, S. P.

2016-02-01

This study documents and investigates biases in simulating summer surface air temperature (SAT) variability over the continental U.S. in the Coupled Model Intercomparison Project (CMIP5) Atmospheric Model Intercomparison Project (AMIP). Empirical orthogonal function (EOF) and multivariate regression analyses are used to assess the relative importance of circulation and the land surface feedback at setting summer SAT over a 30-year period (1979-2008). In observations, regions of high SAT variability are closely associated with midtropospheric highs and subsidence, consistent with adiabatic theory (Meehl and Tebaldi 2004, Lau and Nath 2012). Preliminary analysis shows the majority of the AMIP models feature high SAT variability over the central U.S., displaced south and/or west of observed centers of action (COAs). SAT COAs in models tend to be concomitant with regions of high sensible heat flux variability, suggesting an excessive land surface feedback in these models modulate U.S. summer SAT. Additionally, tropical sea surface temperatures (SSTs) play a role in forcing the leading EOF mode for summer SAT, in concert with internal atmospheric variability. There is evidence that models respond to different SST patterns than observed. Addressing issues with the bulk land surface feedback and the SST-forced component of atmospheric variability may be key to improving model skill in simulating summer SAT variability over the U.S.

Electroosmotic flow in capillary channels filled with nonconstant viscosity electrolytes: exact solution of the Navier-Stokes equation.

PubMed

Otevrel, Marek; Klepárník, Karel

2002-10-01

The partial differential equation describing unsteady velocity profile of electroosmotic flow (EOF) in a cylindrical capillary filled with a nonconstant viscosity electrolyte was derived. Analytical solution, based on the general Navier-Stokes equation, was found for constant viscosity electrolytes using the separation of variables (Fourier method). For the case of a nonconstant viscosity electrolyte, the steady-state velocity profile was calculated assuming that the viscosity decreases exponentially in the direction from the wall to the capillary center. Since the respective equations with nonconstant viscosity term are not solvable in general, the method of continuous binding conditions was used to solve this problem. In this method, an arbitrary viscosity profile can be modeled. The theoretical conclusions show that the relaxation times at which an EOF approaches the steady state are too short to have an impact on a separation process in any real systems. A viscous layer at the wall affects EOF significantly, if it is thicker than the Debye length of the electric double layer. The presented description of the EOF dynamics is applicable to any microfluidic systems.

A DC electrophoresis method for determining electrophoretic mobility through the pressure driven negation of electro osmosis

NASA Astrophysics Data System (ADS)

Karam, Pascal; Pennathur, Sumita

2016-11-01

Characterization of the electrophoretic mobility and zeta potential of micro and nanoparticles is important for assessing properties such as stability, charge and size. In electrophoretic techniques for such characterization, the bulk fluid motion due to the interaction between the fluid and the charged surface must be accounted for. Unlike current industrial systems which rely on DLS and oscillating potentials to mitigate electroosmotic flow (EOF), we propose a simple alternative electrophoretic method for optically determining electrophoretic mobility using a DC electric fields. Specifically, we create a system where an adverse pressure gradient counters EOF, and design the geometry of the channel so that the flow profile of the pressure driven flow matches that of the EOF in large regions of the channel (ie. where we observe particle flow). Our specific COMSOL-optimized geometry is two large cross sectional areas adjacent to a central, high aspect ratio channel. We show that this effectively removes EOF from a large region of the channel and allows for the accurate optical characterization of electrophoretic particle mobility, no matter the wall charge or particle size.

Role of Electroosmosis in the Permeation of Neutral Molecules: CymA and Cyclodextrin as an Example

PubMed Central

Bhamidimarri, Satya Prathyusha; Prajapati, Jigneshkumar Dahyabhai; van den Berg, Bert; Winterhalter, Mathias; Kleinekathöfer, Ulrich

2016-01-01

To quantify the flow of small uncharged molecules into and across nanopores, one often uses ion currents. The respective ion-current fluctuations caused by the presence of the analyte make it possible to draw some conclusions about the direction and magnitude of the analyte flow. However, often this flow appears to be asymmetric with respect to the applied voltage. As a possible reason for this asymmetry, we identified the electroosmotic flow (EOF), which is the water transport associated with ions driven by the external transmembrane voltage. As an example, we quantify the contribution of the EOF through a nanopore by investigating the permeation of α-cyclodextrin through CymA, a cyclodextrin-specific channel from Klebsiella oxytoca. To understand the results from electrophysiology on a molecular level, all-atom molecular dynamics simulations are used to detail the effect of the EOF on substrate entry to and exit from a CymA channel in which the N-terminus has been deleted. The combined experimental and computational results strongly suggest that one needs to account for the significant contribution of the EOF when analyzing the penetration of cyclodextrins through the CymA pore. This example study at the same time points to the more general finding that the EOF needs to be considered in translocation studies of neutral molecules and, at least in many cases, should be able to help in discriminating between translocation and binding events. PMID:26840725

Role of Electroosmosis in the Permeation of Neutral Molecules: CymA and Cyclodextrin as an Example.

PubMed

Bhamidimarri, Satya Prathyusha; Prajapati, Jigneshkumar Dahyabhai; van den Berg, Bert; Winterhalter, Mathias; Kleinekathöfer, Ulrich

2016-02-02

To quantify the flow of small uncharged molecules into and across nanopores, one often uses ion currents. The respective ion-current fluctuations caused by the presence of the analyte make it possible to draw some conclusions about the direction and magnitude of the analyte flow. However, often this flow appears to be asymmetric with respect to the applied voltage. As a possible reason for this asymmetry, we identified the electroosmotic flow (EOF), which is the water transport associated with ions driven by the external transmembrane voltage. As an example, we quantify the contribution of the EOF through a nanopore by investigating the permeation of α-cyclodextrin through CymA, a cyclodextrin-specific channel from Klebsiella oxytoca. To understand the results from electrophysiology on a molecular level, all-atom molecular dynamics simulations are used to detail the effect of the EOF on substrate entry to and exit from a CymA channel in which the N-terminus has been deleted. The combined experimental and computational results strongly suggest that one needs to account for the significant contribution of the EOF when analyzing the penetration of cyclodextrins through the CymA pore. This example study at the same time points to the more general finding that the EOF needs to be considered in translocation studies of neutral molecules and, at least in many cases, should be able to help in discriminating between translocation and binding events. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The influence of ENSO, PDO and PNA on secular rainfall variations in Hawai`i

NASA Astrophysics Data System (ADS)

Frazier, Abby G.; Elison Timm, Oliver; Giambelluca, Thomas W.; Diaz, Henry F.

2017-11-01

Over the last century, significant declines in rainfall across the state of Hawai`i have been observed, and it is unknown whether these declines are due to natural variations in climate, or manifestations of human-induced climate change. Here, a statistical analysis of the observed rainfall variability was applied as first step towards better understanding causes for these long-term trends. Gridded seasonal rainfall from 1920 to 2012 is used to perform an empirical orthogonal function (EOF) analysis. The leading EOF components are correlated with three indices of natural climate variations (El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Pacific North American (PNA)), and multiple linear regression (MLR) is used to model the leading components with climate indices. PNA is the dominant mode of wet season (November-April) variability, while ENSO is most significant in the dry season (May-October). To assess whether there is an anthropogenic influence on rainfall, two methods are used: a linear trend term is included in the MLR, and pattern correlation coefficients (PCC) are calculated between recent rainfall trends and future changes in rainfall projected by downscaling methods. PCC results indicate that recent observed rainfall trends in the wet season are positively correlated with future expected changes in rainfall, while dry season PCC results do not show a clear pattern. The MLR results, however, show that the trend term adds significantly to model skill only in the dry season. Overall, MLR and PCC results give weak and inconclusive evidence for detection of anthropogenic signals in the observed rainfall trends.

Topside Ionospheric Response to Solar EUV Variability

NASA Astrophysics Data System (ADS)

Anderson, P. C.; Hawkins, J.

2015-12-01

We present an analysis of 23 years of thermal plasma measurements in the topside ionosphere from several DMSP spacecraft at ~800 km. The solar cycle variations of the daily averaged densities, temperatures, and H+/O+ ratios show a strong relationship to the solar EUV as described by the E10.7 solar EUV proxy with cross-correlation coefficients (CCCs) with the density greater than 0.85. The H+/O+ varies dramatically from solar maximum when it is O+ dominated to solar minimum when it is H+ dominated. These ionospheric parameters also vary strongly with season, particularly at latitudes well away from the equator where the solar zenith angle (SZA) varies greatly with season. There are strong 27-day solar rotation periodicities in the density, associated with the periodicities in the solar EUV as measured by the TIMED SEE and SDO EVE instruments, with CCCs at times greater than 0.9 at selected wavelengths. Empirical Orthogonal Function (EOF) analysis captures over 95% of the variation in the density over the 23 years in the first two principle components. The first principle component (PC1) is clearly associated with the solar EUV showing a 0.91 CCC with the E10.7 proxy while the PC1 EOFs remain relatively constant with latitude indicating that the solar EUV effects are relatively independent of latitude. The second principle component (PC2) is clearly associated with the SZA variation, showing strong correlations with the SZA and the concomitant density variations at latitudes away from the equator and with the PC2 EOFs having magnitudes near zero at the equator and maximum at high latitude. The magnitude of the variation of the response of the topside ionosphere to solar EUV variability is shown to be closely related to the composition. This is interpreted as the result of the effect of composition on the scale height in the topside ionosphere and the "pivot effect" in which the variation in density near the F2 peak is expected to be amplified by a factor of e at an altitude a scale height above the F2 peak. When the topside ionosphere is H+ dominated, DMSP may be much less than a scale height above the F2 peak while when it is O+ dominated, DMSP may be several scale heights above the F2 peak.

Modulation of Electroosmotic Flow through Skin: Effect of Poly(Amidoamine) Dendrimers

PubMed Central

Kim, Hye Ji; Oh, Seaung Youl

2018-01-01

The objective of this work is to evaluate the effect of polyamidoamine (PAMAM) dendrimers on electroosmotic flow (EOF) through skin. The effect of size and concentration of dendrimer was studied, using generation 1, 4 and 7 dendrimer (G1, G4 and G7, respectively). As a marker molecule for the direction and magnitude of EOF, a neutral molecule, acetoaminophen (AAP) was used. The visualization of dendrimer permeation into the current conducting pore (CCP) of skin was made using G4–fluorescein isothiocyanate (FITC) conjugate and confocal microscopy. Without dendrimer, anodal flux of AAP was much higher than cathodal or passive flux. When G1 dendrimer was added, anodal flux decreased, presumably due to the decrease in EOF by the association of G1 dendrimer with net negative charge in CCP. As the generation increased, larger decrease in anodal flux was observed, and the direction of EOF was reversed. Small amount of methanol used for the preparation of dendrimer solution also contributed to the decrease in anodal flux of AAP. Cross-sectional view perpendicular to the skin surface by confocal laser scanning microscope (CLSM) study showed that G4 dendrimer-FITC conjugate (G4-FITC) can penetrate into the viable epidermis and dermis under anodal current. The permeation route seemed to be localized on hair follicle region. These results suggest that PAMAM dendrimers can permeate into CCP and change the magnitude and direction of EOF. Overall, we obtained a better understanding on the mechanistic insights into the electroosmosis phenomena and its role on flux during iontophoresis. PMID:29310428

Impact of cover crop, irrigation and season on nutrient and sediment in the runoff water measured at the edge-of-fields in northeast Arkansas

USDA-ARS?s Scientific Manuscript database

Improved understanding of water quality at the edge-of-field (EOF) from production-size fields is needed to better inform agriculture and resource managers regarding sustainable farming practices and environmental stewardship. We measured runoff water quality at EOF of paired commercial fields in Mi...

Electroosmotic flow in a microcavity with nonuniform surface charges.

PubMed

Halpern, David; Wei, Hsien-Hung

2007-08-28

In this work, we theoretically explore the characteristics of electroosmostic flow (EOF) in a microcavity with nonuniform surface charges. It is well known that a uniformly charged EOF does not give rise to flow separation because of its irrotational nature, as opposed to the classical problem of viscous flow past a cavity. However, if the cavity walls bear nonuniform surface charges, then the similitude between electric and flow fields breaks down, leading to the generation of vorticity in the cavity. Because this vorticity must necessarily diffuse into the exterior region that possesses a zero vorticity set by a uniform EOF, a new flow structure emerges. Assuming Stokes flow, we employ a boundary element method to explore how a nonuniform charge distribution along the cavity surface affects the flow structure. The results show that the stream can be susceptible to flow separation and exhibits a variety of flow structures, depending on the distributions of zeta potentials and the aspect ratio of the cavity. The interactions between patterned EOF vortices and Moffatt eddies are further demonstrated for deep cavities. This work not only has implications for electrokinetic flow induced by surface imperfections but also provides optimal strategies for achieving effective mixing in microgrooves.

Using the Quantile Mapping to improve a weather generator

NASA Astrophysics Data System (ADS)

Chen, Y.; Themessl, M.; Gobiet, A.

2012-04-01

We developed a weather generator (WG) by using statistical and stochastic methods, among them are quantile mapping (QM), Monte-Carlo, auto-regression, empirical orthogonal function (EOF). One of the important steps in the WG is using QM, through which all the variables, no matter what distribution they originally are, are transformed into normal distributed variables. Therefore, the WG can work on normally distributed variables, which greatly facilitates the treatment of random numbers in the WG. Monte-Carlo and auto-regression are used to generate the realization; EOFs are employed for preserving spatial relationships and the relationships between different meteorological variables. We have established a complete model named WGQM (weather generator and quantile mapping), which can be applied flexibly to generate daily or hourly time series. For example, with 30-year daily (hourly) data and 100-year monthly (daily) data as input, the 100-year daily (hourly) data would be relatively reasonably produced. Some evaluation experiments with WGQM have been carried out in the area of Austria and the evaluation results will be presented.

An Optimal Design for Placements of Tsunami Observing Systems Around the Nankai Trough, Japan

NASA Astrophysics Data System (ADS)

Mulia, I. E.; Gusman, A. R.; Satake, K.

2017-12-01

Presently, there are numerous tsunami observing systems deployed in several major tsunamigenic regions throughout the world. However, documentations on how and where to optimally place such measurement devices are limited. This study presents a methodological approach to select the best and fewest observation points for the purpose of tsunami source characterizations, particularly in the form of fault slip distributions. We apply the method to design a new tsunami observation network around the Nankai Trough, Japan. In brief, our method can be divided into two stages: initialization and optimization. The initialization stage aims to identify favorable locations of observation points, as well as to determine the initial number of observations. These points are generated based on extrema of an empirical orthogonal function (EOF) spatial modes derived from 11 hypothetical tsunami events in the region. In order to further improve the accuracy, we apply an optimization algorithm called a mesh adaptive direct search (MADS) to remove redundant measurements from the initially generated points by the first stage. A combinatorial search by the MADS will improve the accuracy and reduce the number of observations simultaneously. The EOF analysis of the hypothetical tsunamis using first 2 leading modes with 4 extrema on each mode results in 30 observation points spread along the trench. This is obtained after replacing some clustered points within the radius of 30 km with only one representative. Furthermore, the MADS optimization can improve the accuracy of the EOF-generated points by approximately 10-20% with fewer observations (23 points). Finally, we compare our result with the existing observation points (68 stations) in the region. The result shows that the optimized design with fewer number of observations can produce better source characterizations with approximately 20-60% improvement of accuracies at all the 11 hypothetical cases. It should be note, however, that our design is a tsunami-based approach, some of the existing observing systems are equipped with additional devices to measure other parameter of interests, i.e., for monitoring seismic activities.

Intraseasonal variability of winter precipitation over central asia and the western tibetan plateau from 1979 to 2013 and its relationship with the North Atlantic Oscillation

NASA Astrophysics Data System (ADS)

Liu, Heng; Liu, Xiaodong; Dong, Buwen

2017-09-01

Winter precipitation over Central Asia and the western Tibetan Plateau (CAWTP) is mainly a result of the interaction between the westerly circulation and the high mountains around the plateau. Empirical Orthogonal Functions (EOFs), Singular Value Decomposition (SVD), linear regression and composite analysis were used to analyze winter daily precipitation and other meteorological elements in this region from 1979 to 2013, in order to understand how interactions between the regional circulation and topography affect the intraseasonal variability in precipitation. The SVD analysis shows that the winter daily precipitation variability distribution is characterized by a dipole pattern with opposite signs over the northern Pamir Plateau and over the Karakoram Himalaya, similar to the second mode of EOF analysis. This dipole pattern of precipitation anomaly is associated with local anomalies in both the 700 hPa moisture transport and the 500 hPa geopotential height and is probably caused by oscillations in the regional and large-scale circulations, which can influence the westerly disturbance tracks and water vapor transport. The linear regression shows that the anomalous mid-tropospheric circulation over CAWTP corresponds to an anti-phase variation of the 500 hPa geopotential height anomalies over the southern and northern North Atlantic 10 days earlier (at 95% significance level), that bears a similarity to the North Atlantic Oscillation (NAO). The composite analysis reveals that the NAO impacts the downstream regions including CAWTP by controlling south-north two branches of the middle latitude westerly circulation around the Eurasian border. During the positive phases of the NAO, the northern branch of the westerly circulation goes around the northwest Tibetan Plateau, whereas the southern branch encounters the southwest Tibetan Plateau, which leads to reduced precipitation over the northern Pamir Plateau and increased precipitation over the Karakoram Himalaya, and vice versa.

Variability in pigment concentration in warm-core rings as determined by coastal zone color scanner satellite imagery from the Mid-Atlantic Bight

NASA Technical Reports Server (NTRS)

Garcia-Moliner, Graciela; Yoder, James A.

1994-01-01

A time series of coastal zone color scanner (CZCS) derived chlorophyll (CZCS-chl) and sea surface temperature (SST) satellite imagery was developed for the Mid-Atlantic Bight (MAB). Warm-core rings (WCR) were identified by both the warmer SST signal as well as the low pigment concentrations of their cores. The variation in pigment concentrations and SST observed in satellite imagery over the geographic range and life span of four WCRs is investigated. The hypotheses are that pigment concentration increase during the lifetime of the WCR is a response to processes such as convective overturn, upwelling, edge enhancement due to increased vertical mixing, active convergence, or lateral exchange. Empirical orthogonal function analysis (EOF) is used to investigate the relationship between SST and pigment patterns observed in the presence of a WCR. The first two EOF modes explain more than 80% of the variability observed in all four WCRs and in both (SST and pigment) data sets. The results of this study show that, at the synoptic scales of staellite data, the variability observed in the WCRs is greater at the periphery of the rings. These results show that advective entrainment, rather than processes at ring center (e.g., shoaling of the pycnocline/nutricline in response to frictional decay) or at the periphery due to other processes such as vertical mixing, is the mechanism responsible for the observed variability.

Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

NASA Astrophysics Data System (ADS)

Xiao, Ziniu; Li, Delin

2016-06-01

The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

Multi-sensor Oceanographic Correlations for Pacific Hake Acoustic Survey Improvement

NASA Astrophysics Data System (ADS)

Brozen, M.; Hillyer, N.; Holt, B.; Armstrong, E. M.

2010-12-01

North Pacific hake (Merluccius productus), the most abundant groundfish along the Pacific coast of northwestern America, are an essential source of income for the coastal region from southern California to British Columbia, Canada. However, hake abundance and distribution are highly variable among years, exhibiting variance in both the north-south and east-west distribution as seen in the results from biannual acoustic surveys. This project is part of a larger undertaking, ultimately focused on the prediction of hake distribution to improve the distribution of survey effort and precision of stock assessments in the future. Four remotely sensed oceanographic variables are examined as a first step in improving our understanding the relationship between the intensity of coastal upwelling and other ocean dynamics, and the north-south summer hake distribution. Sea surface height, wind vectors, chlorophyll - a concentrations, and sea surface temperature were acquired from several satellites, including AVHRR, SeaWifs, TOPEX/Poseidon, Jason-1, Jason-2, SSM/I, ASMR-E, and QuikScat. Data were aligned to the same spatial and temporal resolution, and these re-gridded data were then analyzed using empirical orthogonal functions (EOFs). EOFs were used as a spatio-temporally compact representation of the data and to reduce the co-variability of the multiple time series in the dataset. The EOF results were plotted and acoustic survey results were overlaid to understand differences between regions. Although this pilot project used data from only a single year (2007), it demonstrated a methodology for reducing dimensionality of linearly related satellite variables that can used in future applications, and provided insight into multi-dimensional ocean characteristics important for hake distribution.

Atmospheric soluble dust records from a Tibetan ice core: Possible climate proxies and teleconnection with the Pacific Decadal Oscillation

NASA Astrophysics Data System (ADS)

Grigholm, B.; Mayewski, P. A.; Kang, S.; Zhang, Y.; Kaspari, S.; Sneed, S. B.; Zhang, Q.

2009-10-01

In autumn 2005, a joint expedition between the University of Maine and the Institute of Tibetan Plateau Research recovered three ice cores from Guoqu Glacier (33°34'37.8″N, 91°10'35.3″E, 5720 m above sea level) on the northern side of Mt. Geladaindong, central Tibetan Plateau. Isotopes (δ18O), major soluble ions (Na+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-), and radionuclide (β-activity) measurements from one of the cores revealed a 70-year record (1935-2005). Statistical analysis of major ion time series suggests that atmospheric soluble dust species dominate the chemical signature and that background dust levels conceal marine ion species deposition. The soluble dust time series have interspecies relations and common structure (empirical orthogonal function (EOF) 1), suggesting a similar soluble dust source or transport route. Annual and seasonal correlations between the EOF 1 time series and National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis climate variables (1948-2004) suggest that the Mt. Geladaindong ice core record provides a proxy for local and regional surface pressure. An approximately threefold decrease of soluble dust concentrations in the middle to late 1970s, accompanied by regional increases in pressure and temperature and decreases in wind velocity, coincides with the major 1976-1977 shift of the Pacific Decadal Oscillation (PDO) from a negative to a positive state. This is the first ice core evidence of a potential teleconnection between central Asian atmospheric soluble dust loading and the PDO. Analysis of temporally longer ice cores from Mt. Geladaindong may enhance understanding of the relationship between the PDO and central Asian atmospheric circulation and subsequent atmospheric soluble dust loading.

Dynamically formed admicelle layer to control the amplitude of cathodic electroosmotic flow.

PubMed

Erny, Guillaume L; Gonçalves, Bruna M; Esteves, Valdemar I

2012-09-21

In this manuscript, a method to precisely adjust the amplitude of a cathodic electroosmotic flow is described. The method uses a capillary pre-coated with a cationic polymer (polybrene), in presence of an anionic surfactant such as sodium dodecyl sulfate. At low concentration of surfactant, molecules will self-assemble to form an immobilized hemimicelle layer with the anionic "head" in contact with the cationic coating and the hydrophobic tail reaching into the background electrolyte. At higher concentration, surfactant molecules in solution will then interact, via hydrophobic interactions, to form an admicelle layer. It has been demonstrated that the admicelle layer can be constructed with either pure anionic surfactant (SDS), or a mixture of anionic and neutral surfactants. Admicelle coatings can be used to control the electroosmotic flow (EOF). While at low surfactant concentration the amplitude of the EOF depends on the concentration of the surfactants concentration, when this concentration reaches the critical admicelle concentration the EOF becomes near constant. The amplitude of the EOF can also be adjusted via the relative proportion of neutral and ionic surfactant in solution. Using this approach, the EOF was varied from 0.450 to 3.848 × 10(-8)m(2)V(-1)s(-1) with a precision below 0.050 × 10(-8)m(2)V(-1)s(-1) (standard deviation measured with three replicates). The coating has been tested using a mix of triazines (atrazine, simazine and terbuthylazine) and a beer sample. With the beer sample an average relative standard deviation of 1.5% for the migration time and of 2.2% for the corrected peak area was obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Phenotypic homogeneity with minor deviance in osmotic fragility of Sahel goat erythrocytes in non-ionic sucrose media during various physiologic states.

PubMed

Igbokwe, Nanacha Afifi; Igbokwe, Ikechukwu Onyebuchi

2016-11-01

Erythrocyte swelling in non-ionic sucrose media and the subsequent osmotic lysis are influenced by mechanisms of regulatory volume adjustment and osmotic water permeability. Kinetics of transmembrane water and ion fluxes in varied physiologic states may determine the phenotype of erythrocyte osmotic fragility (EOF) and affect estimates of EOF. Effects of sex, age, late pregnancy (third trimester) and lactation on the haemolysis of Sahel goat erythrocytes incubated in a series of hyposmotic non-ionic sucrose media were investigated. The fragiligram was sigmoidal in 72 (97%) out of 74 goats. Two male (3%) goats with low and high extreme median erythrocyte fragilities (MEF), had non-sigmoidal curves. The mean fragilities at osmolarities of 30-300 mosmol/L of sucrose and the mean osmolarities responsible for 10%-90% haemolysis (CH10-CH90) were not significantly different between males and non-pregnant dry (NPD) females, amongst the age groups and between pregnant or lactating and NPD female goats. The MEF (CH50) of the goats were at osmolarities of 126-252 mosmol/L (median of data: 171 mosmol/L) with a mean of 175.24±16.20 mosmol/L. Therefore, phenotypic homogeneity of EOF occurred with minor deviance, since EOF variables were not differentiated by sex, age, late pregnancy or lactation. Physiologic states of the goat did not affect EOF phenotype in non-ionic sucrose media. Sigmoidal fragility phenotype seemed to be homogeneously conserved by osmoregulatory mechanisms not partitioned by sex, age, late pregnancy or lactation, but a minor non-sigmoidal curve might have occurred due to altered erythrocyte osmotic behaviour that would require further investigation.

Secondary electroosmotic flow in microchannels with nonuniform and asymmetric Zeta potential

NASA Astrophysics Data System (ADS)

Zhang, Jinbai; He, Guowei; Liu, Feng

2004-11-01

Microfluidics has a broad range of applications in biotechnology, such as sample injection, drug delivering, solution mixing, and separations. All of these techniques require handling fluids in the low Reynolds number (Re) regime. Electroosmotic flow (EOF) or electroosmocitcs is the bulk movement of liquid relative to a stationary surface due to an externally applied electronic field. It is an alternative to pressure-driven flows with convenient implementation The driving force for EOF is dependent on the zeta potential. Previous reseraches focus on the nonuniform Zeta potential. In the present work, we consider nonuniform and asymmetric Zeta potential. The effects of asymmetric Zeta potential on the EOF are investigated analytically and simulated numerically. It is demonstrated that the nonuniform and asymmetric Zeta potential can generate more flow patterns for microfluidic control compared to symmetric Zeta potential.

Reconstruction of Missing Pixels in Satellite Images Using the Data Interpolating Empirical Orthogonal Function (DINEOF)

NASA Astrophysics Data System (ADS)

Liu, X.; Wang, M.

2016-02-01

For coastal and inland waters, complete (in spatial) and frequent satellite measurements are important in order to monitor and understand coastal biological and ecological processes and phenomena, such as diurnal variations. High-frequency images of the water diffuse attenuation coefficient at the wavelength of 490 nm (Kd(490)) derived from the Korean Geostationary Ocean Color Imager (GOCI) provide a unique opportunity to study diurnal variation of the water turbidity in coastal regions of the Bohai Sea, Yellow Sea, and East China Sea. However, there are lots of missing pixels in the original GOCI-derived Kd(490) images due to clouds and various other reasons. Data Interpolating Empirical Orthogonal Function (DINEOF) is a method to reconstruct missing data in geophysical datasets based on Empirical Orthogonal Function (EOF). In this study, the DINEOF is applied to GOCI-derived Kd(490) data in the Yangtze River mouth and the Yellow River mouth regions, the DINEOF reconstructed Kd(490) data are used to fill in the missing pixels, and the spatial patterns and temporal functions of the first three EOF modes are also used to investigate the sub-diurnal variation due to the tidal forcing. In addition, DINEOF method is also applied to the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (SNPP) satellite to reconstruct missing pixels in the daily Kd(490) and chlorophyll-a concentration images, and some application examples in the Chesapeake Bay and the Gulf of Mexico will be presented.

Conditions for similitude and the effect of finite Debye length in electroosmotic flows.

PubMed

Oh, Jung Min; Kang, Kwan Hyoung

2007-06-15

Under certain conditions, the velocity field is similar to the electric field for electroosmotic flow (EOF) inside a channel. There was a disagreement between investigators on the necessity of the infinitesimal-Reynolds-number condition for the similarity when the Helmholtz-Smoluchowski relation is applied throughout the boundaries. What is puzzling is a recent numerical result that showed, contrary to the conventional belief, an evident Reynolds number dependence of the EOF. We show here that the notion that the infinitesimal-Reynolds-number condition is required originates from the misunderstanding that the EOF is the Stokes flow. We point out that the EOF becomes the potential flow when the Helmholtz-Smoluchowski relation is applied at the boundaries. We carry out a numerical simulation to investigate the effect of finiteness of the Debye length and the vorticity layer inherently existing at the channel wall. We show that the Reynolds number dependence of the previous numerical simulation resulted from the finiteness of the Debye length and subsequent convective transport of vorticity toward the bulk flow. We discuss in detail how the convection of vorticity occurs and what factors are involved in the transport process, after carrying out the simulation for different Reynolds numbers, Debye lengths, corner radii, and geometries.

Effect of the electric field ratio on electroosmotic flow patterns in cross-shaped microchannels by the lattice-Boltzmann Method

NASA Astrophysics Data System (ADS)

Socias, Alvaro; Oyarzun, Diego; Guzman, Amador

2014-11-01

The electroosmotic flow (EOF) pattern characteristics in cross-shaped microchannels flow are important features when either suppressing or enhancing flow features for injection and separation or mixing of multiple species are the wanted objectives. There are situations in EOF in cross-shaped microchannels where the fluid flows toward unexpected and unwanted directions under a given external electric field that depends of both the applied electric field and lengths of the different channels. This article describes the effect of the electric field ratio, defined as the ratio between longitudinal nominal electric field ELong = (VE-VW) /(LW + LE) and the nominal electric field E a = (VS-VE) /(VS + VE) , where E, S and W define the east, south and west directions of the cross-shaped microchannel; V is the externally applied voltage and L is the length, on the EOF characteristics in a cross-shaped microchannel. We use the lattice-Boltzmann method (LBM) for solving the discretized Boltzmann Transport Equation (BTE) describing the coupled processes of hydrodynamics and electrodynamic. Our numerical simulations allow us to determine the EOF pattern for a wide range of the electric field ratio and Ea such that inverted flow features are captured and described, which are very important to determine for flow separation or mixing.

The power of power: electrokinetic control of PAH interactions with exfoliated graphite.

PubMed

Qin, Jinyi; Moustafa, Ahmed; Harms, Hauke; El-Din, Mohamed Gamal; Wick, Lukas Y

2015-05-15

Exfoliated graphite (EG) exhibits exceptional sorption capacity for petroleum and dissolved hydrocarbons owing to its highly hydrophobic surface and wide pore size distribution. The high price of preparing EG, however, restricts its application. Methods which increase the rate or extent of sorption to EG even further are thus longed for. Here, we assess the effects of weak direct current (DC) fields on the sorption of the polycyclic aromatic hydrocarbon phenanthrene (PHE) to EG. DC applied to an ionic solution in a solid matrix invokes electroosmotic flow (EOF), i.e., the surface charge-induced movement of the solution. EG was exposed to weak DC fields in the presence of dissolved PHE to test if EOF increases transport of PHE to poorly accessible sorption sites. DC fields increased PHE sorption rates in EG sevenfold and reduced the desorption rate of sorbed PHE by >99%. EOF thus appeared to be highly effective in translocating PHE into pores, which contribute most of the sorption sites, but are difficult to access in the absence of EOF by molecular diffusion only. The observed 'power of power' may be used to kinetically regulate the interaction of sorbates with EG or other porous sorbents in environmental (bio-) technology. Copyright © 2015 Elsevier B.V. All rights reserved.

Spatial patterns of soil moisture connected to monthly-seasonal precipitation variability in a monsoon region

Treesearch

Yongqiang Liu

2003-01-01

The relations between monthly-seasonal soil moisture and precipitation variability are investigated by identifying the coupled patterns of the two hydrological fields using singular value decomposition (SVD). SVD is a technique of principal component analysis similar to empirical orthogonal knctions (EOF). However, it is applied to two variables simultaneously and is...

Separation of organic cations using novel background electrolytes by capillary electrophoresis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steiner, S.; Fritz, J.

2008-02-12

A background electrolyte for capillary electrophoresis containing tris(-hydroxymethyl) aminomethane (THAM) and ethanesulfonic acid (ESA) gives excellent efficiency for separation of drug cations with actual theoretical plate numbers as high as 300,000. However, the analyte cations often elute too quickly and consequently offer only a narrow window for separation. The best way to correct this is to induce a reverse electroosmotic flow (EOF) that will spread out the peaks by slowing their migration rates, but this has always been difficult to accomplish in a controlled manner. A new method for producing a variable EOF is described in which a low variablemore » concentration of tributylammonium- or triethylammonium ESA is added to the BGE. The additive equilibrates with the capillary wall to give it a positive charge and thereby produce a controlled opposing EOF. Excellent separations of complex drug mixtures were obtained by this method.« less

[Characteristics of electroosmotic flow in open-tubular capillary electrochromatography with magnetic nanoparticle coating as mixed-mode stationary phase].

PubMed

Qin, Sasa; Zhou, Chaoran; Zhu, Yaxian; Ren, Zhiyu; Zhang, Lingyi; Fu, Honggang; Zhang, Weibing

2011-09-01

A novel open-tubular capillary electrochromatography (OT-CEC) column with magnetic nanoparticle coating as mixed-mode stationary phase was prepared. The mixed-mode stationary phases were obtained by mixing C18 and amino modified magnetic nanoparticles with different ratios. The mixed modified magnetic nanoparticles as stationary phase were introduced into the capillary by using external magnetic force. The magnetic nanoparticle coating can be easily regenerated by removing the external magnetic field, and applied to other separation modes. The characteristics of electroosmotic flow (EOF) were theoretically investigated through the effect of physicochemical properties of different stationary phases on EOF. The experiment was conducted under different ratios of mixed-mode stationary phases and coating lengths, and it was verified that the theoretical conclusions accorded with the experimental results. It was shown that the EOF can be easily adjusted by changing the ratio of stationary phases or the number of permanent magnets.

Predicting the Dominant Patterns of Subseasonal Variability of Wintertime Surface Air Temperature in Extratropical Northern Hemisphere

NASA Astrophysics Data System (ADS)

Lin, Hai

2018-05-01

Skillfully predicting persistent extreme temperature anomalies more than 10 days in advance remains a challenge although it is of great value to the society. Here the two leading modes of subseasonal variability of surface air temperature over the extratropical Northern Hemisphere in boreal winter are identified with pentad (5 days) averaged data. They are well separated geographically, dominating temperature variability in North America and Eurasia, respectively. There exists a two-pentad lagged correlation between these two modes, implying an intercontinental link of temperature variability. Forecast skill of these two modes is evaluated based on three operational subseasonal prediction models. The results show that useful forecasts of the Eurasian mode (EOF2) can be achieved four pentads in advance, which is more skillful than the North American mode (EOF1). EOF2 is found to benefit from the Madden-Julian Oscillation signal in the initial condition.

Investigations of the preferred modes of north Pacific jet variability, their downstream impacts, and tropical and extratropical precursors

NASA Astrophysics Data System (ADS)

Griffin, Kyle S.

Time extended EOF (TE-EOF) analysis is employed to examine the synoptic-scale evolution of the two leading modes of north Pacific jet stream variability, namely its zonal extension/retraction (TE-EOF 1) and the north/south shift of its exit region (TE-EOF 2). Composite analyses are constructed preceding and following peaks in the principal component associated with each of the two TE-EOFs, providing insight into the preferred evolutions of the north Pacific jet. Jet extension events are associated with an anomalous Gulf of Alaska cyclone, while jet retractions are associated with an anomalous ridge over the Aleutians. Similar but shifted upper level patterns are noted with the corresponding poleward/equatorward shifted jet phases, with the poleward (equatorward) shift of the jet exit region associated with anomalous low-level warmth (cold) over western North America. Such composites also suggest connections between certain phases of these leading modes of jet variability and deep convection in the tropics, a connection that has been challenging to physically diagnose in previous studies. The isentropic pressure depth measures the mass contained within an isentropic layer in a given grid column, enabling the tracking of mass exhausted by deep convection. The gradient of isentropic pressure depth is directly associated with the vertical geostrophic wind shear in that layer and thus provides a means to track the influence of convective mass flux on the evolution of the jet stream. A case study focused on the extreme North American warm episode of March 2012 demonstrates how positive pressure depth anomalies from a strong MJO event impact the jet stream over eastern Asia and drive a portion of the mid-latitude response that leads to the flow amplification and subsequent downstream warmth. This study demonstrates one way by which isentropic pressure depth can diagnose the impacts of tropical deep convection on the mid-latitude circulation. Using TE-EOFs, composites of isentropic pressure depth are constructed, to examine the evolution of pressure depth anomalies preceding each phase of the two leading modes of jet variability. In jet extension events, a large negative pressure depth anomaly in the 315-330 K isentropic layer and a positive pressure depth anomaly in the 340-355 K isentropic layer align north and south of the climatological jet exit region, respectively. A similar but opposite configuration is found in jet retraction events. During poleward shifted jet events, the configuration of pressure depth anomalies is comparable to that observed in jet extension events, but shifted poleward. Positive pressure depth anomalies in each set of events predominantly originate from either the Maritime Continent or East Asia and track along the climatological jet before impacting the exit region of the jet stream. Negative pressure depth anomalies have similar upstream origins before moving through the jet in a similar manner. These composite evolutions provide insight into the synoptic-scale evolutions that precede the preferred modes of jet variability, highlighting the influence of both mid-latitude weather systems and mass flux from tropical deep convection on North Pacific jet variability.

Interannual correlations between sea surface temperature and concentration of chlorophyll pigment off Punta Eugenia, Baja California, during different remote forcing conditions

NASA Astrophysics Data System (ADS)

Herrera-Cervantes, H.; Lluch-Cota, S. E.; Lluch-Cota, D. B.; Gutiérrez-de-Velasco, G.

2014-05-01

Interannual correlation between satellite-derived sea surface temperature (SST) and surface chlorophyll a (Chl a) are examined in the coastal upwelling zone off Punta Eugenia on the west coast of the Baja California Peninsula, an area than has been identified as having intense biological productivity and oceanographic transition between midlatitude and tropical ocean conditions. We used empirical orthogonal functions (EOF) analysis separately and jointly on the two fields from 1997 through 2007, a time period dominated by different remote forcing: ENSO (El Niño-Southern Oscillation) conditions (weak, moderate and strong) and the largest intrusion of subarctic water reported in the last 50 years. Coastal upwelling index anomalies (CUI) and the multivariate ENSO index (MEI) were used to identify the influence of local (wind stress) and remote (ENSO) forcing over the interannual variability of both variables. The spatial pattern of the individual EOF1 analysis showed the greater variability of SST and Chl a offshore, their corresponding amplitude time series presented the highest peaks during the strong 1997-2000 El Niño-La Niña cycles and during the 2002-2004 period associated to the intrusion of subarctic water. The MEI is well correlated with the individual SST principal component (R ≈ 0.67, P < 0.05) and poorly with the individual Chl a principal component (R = -0.13). The joint EOF1 and the SST-Chl a correlation patterns show the area where both variables covary tightly; a band near the coast where the largest correlations occurred (| R | > 0.4) mainly regulated by ENSO cycles. This was spatially revealed when we calculated the homogeneous correlations for the 1997-1999 El Niño-La Niña period and during the 2002-2004 period, the intrusion of subarctic water period. Both, SST and Chl a showed higher coupling and two distinct physical-biological responses: on average ENSO influence was observed clearly along the coast mostly in SST, while the subarctic water influence, observed offshore and in Bahía Vizcaíno, mostly in Chl a. We found coastal chlorophyll blooms off Punta Eugenia during the 2002-2003 period, an enrichment pattern similar to that observed off the coast of Oregon. These chlorophyll blooms are likely linked to high wind stress anomalies during 2002, mainly at high latitudes. This observation may provide an explanation of why Punta Eugenia is one of the most important biological action centers on the Pacific coast.

The influence of Indian summer monsoon on the climatic regime of Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Rizou, D.; Flocas, H. A.; Bartzokas, A.; Helmis, C. G.

2012-04-01

In a previous study, composite analysis demonstrated that there are significant differences in the atmospheric circulation over the greater Mediterranean region at the upper and lower levels between strong and weak monsoon years. More specifically, in the lower atmosphere the geopotential height anomaly patterns for the extreme Indian summer monsoon (ISM) years indicated the intensification (weakening) of the Azores anticyclone and the Persian trough, which extends from the Asian monsoon towards the Aegean Sea, during strong (weak) ISM years. This further implies that the ISM has an impact on the strong northerly winds blowing over the Aegean Sea, namely "Etesians", which result from the combined action of the two aforementioned major systems. The accompanied continual cool advection in the area was identified in the negative anomalies of the strong 1000 hPa temperature composite over the region. At the same time, in the 500 hPa ω anomaly field it was found that a pronounced subsidence (upward motion) dominates over Eastern Mediterranean during years of strong (weak) ISM, counteracting the advective cooling in the area. The objective of this study is to further investigate the ISM impact on the temperature and wind regime of the Eastern Mediterranean region, with the aid of multivariate statistics. For this purpose, the standardized Dynamic Indian Monsoon Index by Wang and Fan (1999) was used for a period of 44 years (1958-2001) along with ERA40 Reanalysis data, including monthly means of surface air temperature and wind at 850hPa with a horizontal resolution of 0.25° latitude x 0.25° longitude. Initially, the correlation maps of the seasonal anomalies of the two variables upon ISM index are computed and subsequently Empirical Orthogonal Function Analysis (EOF) is carried out on individual fields. Under this framework, correlation coefficients between the derived EOF amplitudes and ISM index are calculated and in order to validate the results from the first method, the EOF modes that exhibit high correlation coefficients are compared to the aforementioned correlation patterns. Our results verify that there is correlation between Indian monsoon and the etesian pattern over the Aegean Sea. Acknowledgments: This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund.

Long-Term Validation and Variability of the Shortwave and Longwave Radiation Data of the GEWEX Surface Radiation Budget (SRB) Project

NASA Technical Reports Server (NTRS)

Zhang, Taiping; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Cox, Stephan J.; Mikovitz, Colleen; Hinkelman, Laura M.

2006-01-01

In this investigation, we make systematic Surface Radiation Budget-Baseline Surface Radiation Network (SRB-BSRN), Surface Radiation Data Centre (SRB-WRDC) and Surface Radiation Budget-Global Energy Balance Archive (SRB-GEBA) comparisons for both shortwave and longwave daily and monthly mean radiation fluxes at the Earth's surface. We first have an overview of all the comparable pairs of data in scatter or scatter density plots. Then we show the time series of the SRB data at grids in which there are ground sites where longterm records of data are available for comparison. An overall very good agreement between the SRB data and ground observations is found. To see the variability of the SRB data during the 21.5 years, we computed the global mean and its linear trend. No appreciable trend is detected at the 5% level. The empirical orthogonal functions (EOF) of the SRB deseasonalized shortwave downward flux are computed over the Pacific region, and the first EOF coefficient is found to be correlated with the ENSO Index at a high value of coefficient of 0.7083.

Results on SSH neural network forecasting in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Rixen, Michel; Beckers, Jean-Marie; Alvarez, Alberto; Tintore, Joaquim

2002-01-01

Nowadays, satellites are the only monitoring systems that cover almost continuously all possible ocean areas and are now an essential part of operational oceanography. A novel approach based on artificial intelligence (AI) concepts, exploits pasts time series of satellite images to infer near future ocean conditions at the surface by neural networks and genetic algorithms. The size of the AI problem is drastically reduced by splitting the spatio-temporal variability contained in the remote sensing data by using empirical orthogonal function (EOF) decomposition. The problem of forecasting the dynamics of a 2D surface field can thus be reduced by selecting the most relevant empirical modes, and non-linear time series predictors are then applied on the amplitudes only. In the present case study, we use altimetric maps of the Mediterranean Sea, combining TOPEX-POSEIDON and ERS-1/2 data for the period 1992 to 1997. The learning procedure is applied to each mode individually. The final forecast is then reconstructed form the EOFs and the forecasted amplitudes and compared to the real observed field for validation of the method.

Unsteady electroosmosis in a microchannel with Poisson-Boltzmann charge distribution.

PubMed

Chang, Chien C; Kuo, Chih-Yu; Wang, Chang-Yi

2011-11-01

The present study is concerned with unsteady electroosmotic flow (EOF) in a microchannel with the electric charge distribution described by the Poisson-Boltzmann (PB) equation. The nonlinear PB equation is solved by a systematic perturbation with respect to the parameter λ which measures the strength of the wall zeta potential relative to the thermal potential. In the small λ limits (λ<1), we recover the linearized PB equation - the Debye-Hückel approximation. The solutions obtained by using only three terms in the perturbation series are shown to be accurate with errors <1% for λ up to 2. The accurate solution to the PB equation is then used to solve the electrokinetic fluid transport equation for two types of unsteady flow: transient flow driven by a suddenly applied voltage and oscillatory flow driven by a time-harmonic voltage. The solution for the transient flow has important implications on EOF as an effective means for transporting electrolytes in microchannels with various electrokinetic widths. On the other hand, the solution for the oscillatory flow is shown to have important physical implications on EOF in mixing electrolytes in terms of the amplitude and phase of the resulting time-harmonic EOF rate, which depends on the applied frequency and the electrokinetic width of the microchannel as well as on the parameter λ. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Combined EOF/Variational Approach for Mapping Radar-Derived Sea Surface Currents

DTIC Science & Technology

2011-01-13

characterized by specific structure of the artificial gaps introduced into the simulated data set assess the benefits of the gap-filling technique. These...15 minutes and 1-2 km respectively. However, the back-scattered HFR signals suffer from to numerous distortions of artificial and natural origin. As a...data because information on the spatial structure of the velocity field within the gap is implicitly drawn from the idealized covariance function

Coupled cluster investigation on the thermochemistry of dimethyl sulphide, dimethyl disulphide and their dissociation products: the problem of the enthalpy of formation of atomic sulphur

NASA Astrophysics Data System (ADS)

Denis, Pablo A.

2014-04-01

By means of coupled cluster theory and correlation consistent basis sets we investigated the thermochemistry of dimethyl sulphide (DMS), dimethyl disulphide (DMDS) and four closely related sulphur-containing molecules: CH3SS, CH3S, CH3SH and CH3CH2SH. For the four closed-shell molecules studied, their enthalpies of formation (EOFs) were derived using bomb calorimetry. We found that the deviation of the EOF with respect to experiment was 0.96, 0.65, 1.24 and 1.29 kcal/mol, for CH3SH, CH3CH2SH, DMS and DMDS, respectively, when ΔHf,0 = 65.6 kcal/mol was utilised (JANAF value). However, if the recently proposed ΔHf,0 = 66.2 kcal/mol was used to estimate EOF, the errors dropped to 0.36, 0.05, 0.64 and 0.09 kcal/mol, respectively. In contrast, for the CH3SS radical, a better agreement with experiment was obtained if the 65.6 kcal/mol value was used. To compare with experiment avoiding the problem of the ΔHf,0 (S), we determined the CH3-S and CH3-SS bond dissociation energies (BDEs) in CH3S and CH3SS. At the coupled cluster with singles doubles and perturbative triples correction level of theory, these values are 48.0 and 71.4 kcal/mol, respectively. The latter BDEs are 1.5 and 1.2 kcal/mol larger than the experimental values. The agreement can be considered to be acceptable if we take into consideration that these two radicals present important challenges when determining their EOFs. It is our hope that this work stimulates new studies which help elucidate the problem of the EOF of atomic sulphur.

Predictability of the summer East Asian upper-tropospheric westerly jet in ENSEMBLES multi-model forecasts

NASA Astrophysics Data System (ADS)

Li, Chaofan; Lin, Zhongda

2015-12-01

The interannual variation of the East Asian upper-tropospheric westerly jet (EAJ) significantly affects East Asian climate in summer. Identifying its performance in model prediction may provide us another viewpoint, from the perspective of upper-tropospheric circulation, to understand the predictability of summer climate anomalies in East Asia. This study presents a comprehensive assessment of year-to-year variability of the EAJ based on retrospective seasonal forecasts, initiated from 1 May, in the five state-of-the-art coupled models from ENSEMBLES during 1960-2005. It is found that the coupled models show certain capability in describing the interannual meridional displacement of the EAJ, which reflects the models' performance in the first leading empirical orthogonal function (EOF) mode. This capability is mainly shown over the region south of the EAJ axis. Additionally, the models generally capture well the main features of atmospheric circulation and SST anomalies related to the interannual meridional displacement of the EAJ. Further analysis suggests that the predicted warm SST anomalies in the concurrent summer over the tropical eastern Pacific and northern Indian Ocean are the two main sources of the potential prediction skill of the southward shift of the EAJ. In contrast, the models are powerless in describing the variation over the region north of the EAJ axis, associated with the meridional displacement, and interannual intensity change of the EAJ, the second leading EOF mode, meaning it still remains a challenge to better predict the EAJ and, subsequently, summer climate in East Asia, using current coupled models.

Potential impacts of the Arctic on interannual and interdecadal summer precipitation over China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yuefeng; Leung, Lai-Yung R.

2013-02-01

After the end of the 1970s, there has been a tendency for enhanced summer precipitation over South China and the Yangtze River valley and drought over North China and Northeastern China. Coincidentally, Arctic ice concentration has decreased since the late 1970s, with larger reduction in summer than spring. However, the Arctic warming is more significant in spring than summer, suggesting that spring Arctic conditions could be more important in their remote impacts. This study investigates the potential impacts of the Arctic on summer precipitation in China. The leading spatial patterns and time coefficients of the unfiltered, interannual, and interdecadal precipitationmore » (1960-2008) modes were analyzed and compared using empirical orthogonal function (EOF) analysis, which shows that the first three EOFs can capture the principal precipitation patterns (northern, central and southern patterns) over eastern China. Regression of the Arctic spring and summer temperature onto the time coefficients of the leading interannual and interdecadal precipitation modes shows that interdecadal summer precipitation in China is related to the Arctic spring warming, but the relationship with Arctic summer temperature is weak. Moreover, no notable relationships were found between the first three modes of interannual precipitation and Arctic spring or summer temperatures. Finally, correlations between summer precipitation and the Arctic Oscillation (AO) index from January to August were investigated, which indicate that summer precipitation in China correlates with AO only to some extent. Overall, this study suggests important relationships between the Arctic spring temperature and summer precipitation over China at the interdecadal time scale.« less

Land surface and atmospheric conditions associated with heat waves over the Chickasaw Nation in the South Central United States

NASA Astrophysics Data System (ADS)

Lee, Eungul; Bieda, Rahama; Shanmugasundaram, Jothiganesh; Basara Richter, Heather

2016-06-01

Exposure to extreme heat was reconstructed based on regional land-atmosphere processes from 1979 to 2010 in the South Central U.S. The study region surrounds the Chickasaw Nation (CN), a predominantly Native American population with a highly prevalent burden of climate-sensitive chronic diseases. Land surface and atmospheric conditions for summer heat waves were analyzed during spring (March-April-May, MAM) and summer (June-July-August, JJA) based on the Climate and Ocean: Variability, Predictability, and Change maximum temperature definition for heat wave frequency (HWF). The spatial-temporal pattern of HWF was determined using empirical orthogonal function (EOF) analysis and the corresponding principle component time series of the first EOF of HWF. Statistically significant analyses of observed conditions indicated that sensible heat increased and latent heat fluxes decreased with high HWF in the South Central U.S. The largest positive correlations of sensible heat flux to HWF and the largest negative correlations of latent heat flux to HWF were specifically observed over the CN. This is a significantly different energy transfer regime due to less available soil moisture during the antecedent MAM and JJA. The higher sensible heat from dry soil could cause significant warming from the near surface (>2.0°C) to the lower troposphere (>1.5°C), and accumulated boundary layer heat could induce the significant patterns of higher geopotential height and enhance anticyclonic circulations (negative vorticity anomaly) at the midtroposphere. Results suggested a positive land-atmosphere feedback associated with heat waves and called attention to the need for region-specific climate adaptation planning.

Land surface and atmospheric conditions associated with heat waves in the South Central United States

NASA Astrophysics Data System (ADS)

Lee, Eungul; Bieda, Rahama; Shanmugasundaram, Jothiganesh; Richter, Heather

2017-04-01

Exposure to extreme heat was reconstructed based on regional land-atmosphere processes from 1979 to 2010 in the South Central U.S. The study region surrounds the Chickasaw Nation (CN), a predominantly Native American population with a highly prevalent burden of climate-sensitive chronic diseases. Land surface and atmospheric conditions for summer heat waves were analyzed during spring (March-April-May, MAM) and summer (June-July-August, JJA) based on the Climate and Ocean: Variability, Predictability, and Change maximum temperature definition for heat wave frequency (HWF). The spatial-temporal pattern of HWF was determined using empirical orthogonal function (EOF) analysis and the corresponding principle component time series of the first EOF of HWF. Statistically significant analyses of observed conditions indicated that sensible heat increased and latent heat fluxes decreased with high HWF in the South Central U.S. The largest positive correlations of sensible heat flux to HWF and the largest negative correlations of latent heat flux to HWF were specifically observed over the CN. This is a significantly different energy transfer regime due to less available soil moisture during the antecedent MAM and JJA. The higher sensible heat from dry soil could cause significant warming from the near surface (> 2.0°C) to the lower troposphere (> 1.5°C), and accumulated boundary layer heat could induce the significant patterns of higher geopotential height and enhance anticyclonic circulations (negative vorticity anomaly) at the midtroposphere. Results suggested a positive land-atmosphere feedback associated with heat waves and called attention to the need for region-specific climate adaptation planning.

Rigorous Characterisation of a Novel, Statistically-Based Ocean Colour Algorithm for the PACE Mission

NASA Astrophysics Data System (ADS)

Craig, S. E.; Lee, Z.; Du, K.; Lin, J.

2016-02-01

An approach based on empirical orthogonal function (EOF) analysis of ocean colour spectra has been shown to accurately derive inherent optical properties (IOPs) and chlorophyll concentration in scenarios, such as optically complex waters, where standard algorithms often perform poorly. The algorithm has been successfully used in a number of regional applications, and has also shown promise in a global implementation based on the NASA NOMAD data set. Additionally, it has demonstrated the unique ability to derive ocean colour products from top of atmosphere (TOA) signals with either no or minimal atmospheric correction applied. Due to its high potential for use over coastal and inland waters, the EOF approach is currently being rigorously characterised as part of a suite of approaches that will be used to support the new NASA ocean colour mission, PACE (Pre-Aerosol, Clouds and ocean Ecosystem). A major component in this model characterisation is the generation of a synthetic TOA data set using a coupled ocean-atmosphere radiative transfer model, which has been run to mimic PACE spectral resolution, and under a wide range of geographical locations, water constituent concentrations, and sea surface and atmospheric conditions. The resulting multidimensional data set will be analysed, and results presented on the sensitivity of the model to various combinations of parameters, and preliminary conclusions made regarding the optimal implementation strategy of this promising approach (e.g. on a global, optical water type or regional basis). This will provide vital guidance for operational implementation of the model for both existing satellite ocean colour sensors and the upcoming PACE mission.

Synthetic temperature profiles derived from Geosat altimetry: Comparison with air-dropped expendable bathythermograph profiles

NASA Astrophysics Data System (ADS)

Carnes, Michael R.; Mitchell, Jim L.; de Witt, P. Webb

1990-10-01

Synthetic temperature profiles are computed from altimeter-derived sea surface heights in the Gulf Stream region. The required relationships between surface height (dynamic height at the surface relative to 1000 dbar) and subsurface temperature are provided from regression relationships between dynamic height and amplitudes of empirical orthogonal functions (EOFs) of the vertical structure of temperature derived by de Witt (1987). Relationships were derived for each month of the year from historical temperature and salinity profiles from the region surrounding the Gulf Stream northeast of Cape Hatteras. Sea surface heights are derived using two different geoid estimates, the feature-modeled geoid and the air-dropped expendable bathythermograph (AXBT) geoid, both described by Carnes et al. (1990). The accuracy of the synthetic profiles is assessed by comparison to 21 AXBT profile sections which were taken during three surveys along 12 Geosat ERM ground tracks nearly contemporaneously with Geosat overflights. The primary error statistic considered is the root-mean-square (rms) difference between AXBT and synthetic isotherm depths. The two sources of error are the EOF relationship and the altimeter-derived surface heights. EOF-related and surface height-related errors in synthetic temperature isotherm depth are of comparable magnitude; each translates into about a 60-m rms isotherm depth error, or a combined 80 m to 90 m error for isotherms in the permanent thermocline. EOF-related errors are responsible for the absence of the near-surface warm core of the Gulf Stream and for the reduced volume of Eighteen Degree Water in the upper few hundred meters of (apparently older) cold-core rings in the synthetic profiles. The overall rms difference between surface heights derived from the altimeter and those computed from AXBT profiles is 0.15 dyn m when the feature-modeled geoid is used and 0.19 dyn m when the AXBT geoid is used; the portion attributable to altimeter-derived surface height errors alone is 0.03 dyn m less for each. In most cases, the deeper structure of the Gulf Stream and eddies is reproduced well by vertical sections of synthetic temperature, with largest errors typically in regions of high horizontal gradient such as across rings and the Gulf Stream front.

Compilation of Abstracts of Theses Submitted by Candidates for Degrees, 1 October 1981 - 30 September 1982.

DTIC Science & Technology

1983-05-01

the European Center for Medium Range Weather Forecasts is used to define the storm and to calculate the budgets. Important differences are found...geopotential field at 850, 700 and 500mb on a 120 point grid with 5 degree latitude and longitude spacing that is centered on the storm . The 120 EOF... storm movement and intensity during the past 36 hours. The EOF-based regression equations are verified over an independent sample of 50 storms , and

Using empirical orthogonal functions from remote sensing reflectance spectra to predict various phytoplankton pigment concentrations in the Eastern Tropical Atlantic

NASA Astrophysics Data System (ADS)

Bracher, Astrid; Taylor, Bettina; Taylor, Marc; Steinmetz, Francois; Dinter, Tilman; Röttgers, Rüdiger

2014-05-01

Phytoplankton pigments play a major role in photosynthesis and photoprotection. Their composition and abundance give information on characteristics of a phytoplankton community in respect to its acclimation to light, overall biomass and composition of major phytoplankton groups. Most phytoplankton pigments can be measured by applying HPLC techniques to filtered water samples. This method like other mathods analysing water samples in the laboratory is time consuming and therefore only a limited number of samples can be obtained. In order to obtain information on phytoplankton pigment composition with a better temporal and spatial composition, the rationale was to develop a method to get from continuous optical measurements pigment concentrations. We have used remote sensing reflectances (RRS) derived from ship-based hyper-spectral underwater radiometric and from satellite MERIS measurements (using the POLYMER algorithm developed by Steinmetz et al. 2011), sampled in the Eastern Tropical Atlantic, to predict the water surface concentration of various pigments or pigment groups in this area. A statistical model based on Empirical Orthogonal Function (EOF) analysis of these RRS spectra was developed. Then subsequently linear models with measured (collocated) pigment concentrations as the response variable and EOF loadings as predictor variables were constructed. The model results, which have been verified by cross validation, show that from the ship-based RRS measurements the surface concentrations of a suite of pigments and pigment groups can be well predicted, even when only a multi-spectral resolution of RRS data is chosen. Based on the MERIS reflectance data, only concentrations of total chlorophyll-a (chl-a), monovinyl-chl-a and the groups of photoprotective and photosynthetic carotenoids can be obtained with high quality. The model constructed on the satellite reflectances as input was also applied to one month of MERIS POLYMER data to predict for the whole Eastern Tropical Atlantic area the concentration of those pigments. Finally, the potential, limitations and future perspectives for the application of our generic method are discussed.

Metallomesogenic stationary phase for open-tubular capillary electrochromatography.

PubMed

Chen, Jian-Lian

2006-02-01

A synthetic coppermesogenic polymer is prepared and then covalently bonded to the siloxane-based deactivated column as the stationary phases of open-tubular CEC with essentially high phase ratio. The EOF generated from the modified phase is surveyed through conventional aqueous buffers and hydroorganic mobile phases. Zeta potentials, which are computed from the EOF data and the ratio of dielectric constant to viscosity, are plotted as a function of pH, ionic molarity, and compositional range. These plots responsible for the electroosmotic characteristic of the bonded phases are found to be like those of bare fused-silica or deactivated columns through decreasing or increasing the ACN content in the mobile phase, respectively. This two-phase characteristic is basically derived from the polymeric configuration with carboxylato ligands attached onto the polysiloxane backbone. Phthalates and amino acids are suitable probes to examine the two phenomena, more-polar and less-polar mediums, respectively, and to judge whether the chromatographic retention is the major source of separation mechanism. With the mixing modes of Lewis acid-base interaction, dispersive force, and shape discrimination, the chromatographic partition adequately accomplishes the uneasily resolved separations by only CZE mode, although the electrophoretic migration is truly somewhat involved.

A strategy to modulate the electrophoretic behavior in plastic microchips using sodium polystyrene sulfonate.

PubMed

Guo, Jinxiu; Chen, Yu; Zhao, Lizhi; Sun, Ping; Li, Hongli; Zhou, Lei; Wang, Xiayan; Pu, Qiaosheng

2016-12-16

Plastic microchips have been broadly used as disposable microfluidic devices, but the poorly defined surface properties limit their application. Herein, we proved that an anionic polymer could be used as the background electrolyte (BGE) to provide a strong and stable cathodic electroosmotic flow (EOF) and modulate the electrophoretic behavior for efficient separation in relative thicker microchannels (∼75μm id). A cathodic EOF of ∼3.3×10 -4 cm 2 V -1 s -1 was maintained using sodium polystyrene sulfonate (PSSNa) with a molecular weight of 5×10 5 as the BGE, which ensured fluorescein isothiocyanate labeled biogenic amines (BAs) appeared ahead of other components in the electropherograms obtained with microchips of cyclic olefin copolymer. Four selected BAs appeared within 50s and theoretical plate numbers of 8.0×10 5 /m were achieved. The role of PSSNa was evaluated with streaming potential, dynamic light scattering, contact angle and atomic force microscopy. Its functionalities as surface modifier, viscosity regulator and pseudostationary phase were also confirmed. The proposed electrophoretic method was applied in the fast determination of BAs in fish meat samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Study Variability of Seasonal Soil Moisture in Ensemble of CMIP5 Models Over South Asia During 1950-2005

NASA Astrophysics Data System (ADS)

Fahim, A. M.; Shen, R.; Yue, Z.; Di, W.; Mushtaq Shah, S.

2015-12-01

Moisture in the upper most layer of soil column from 14 different models under Coupled Model Intercomparison Project Phase-5 (CMIP5) project were analyzed for four seasons of the year. Aim of this study was to explore variability in soil moisture over south Asia using multi model ensemble and relationship between summer rainfall and soil moisture for spring and summer season. GLDAS (Global Land Data Assimilation System) dataset set was used for comparing CMIP5 ensemble mean soil moisture in different season. Ensemble mean represents soil moisture well in accordance with the geographical features; prominent arid regions are indicated profoundly. Empirical Orthogonal Function (EOF) analysis was applied to study the variability. First component of EOF explains 17%, 16%, 11% and 11% variability for spring, summer, autumn and winter season respectively. Analysis reveal increasing trend in soil moisture over most parts of Afghanistan, Central and north western parts of Pakistan, northern India and eastern to south eastern parts of China, in spring season. During summer, south western part of India exhibits highest negative trend while rest of the study area show minute trend (increasing or decreasing). In autumn, south west of India is under highest negative loadings. During winter season, north western parts of study area show decreasing trend. Summer rainfall has very week (negative or positive) spatial correlation, with spring soil moisture, while possess higher correlation with summer soil moisture. Our studies have significant contribution to understand complex nature of land - atmosphere interactions, as soil moisture prediction plays an important role in the cycle of sink and source of many air pollutants. Next level of research should be on filling the gaps between accurately measuring the soil moisture using satellite remote sensing and land surface modelling. Impact of soil moisture in tracking down different types of pollutant will also be studied.

Total fluorine, extractable organic fluorine, perfluorooctane sulfonate and other related fluorochemicals in liver of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from South China.

PubMed

Yeung, L W Y; Miyake, Y; Wang, Y; Taniyasu, S; Yamashita, N; Lam, P K S

2009-01-01

The concentrations of 10 PFCs (perfluorinated compounds: PFOS, PFHxS, PFOSA, N-EtFOSA, PFDoDA, PFUnDA, PFDA, PFNA, PFOA, and PFHpA) were measured in liver samples of Indo-Pacific humpback dolphins (Sousa chinensis) (n=10) and finless porpoises (Neophocaena phocaenoides) (n=10) stranded in Hong Kong between 2003 and 2007. PFOS was the dominant PFC in the tissues at concentrations ranging at 26-693 ng/g ww in dolphins and 51.3-262 ng/g ww in porpoises. A newly developed combustion ion chromatography for fluorine was applied to measure total fluorine (TF) and extractable organic fluorine (EOF) in these liver samples to understand PFC contamination using the concept of mass balance analysis. Comparisons between the amounts of known PFCs and EOF in the livers showed that a large proportion (approximately 70%) of the organic fluorine in both species is of unknown origin. These investigations are critical for a comprehensive assessment of the risks of these compounds to humans and other receptors.

Drought assessment using multi-sattelite remote sensing in Brazil

NASA Astrophysics Data System (ADS)

Rebello, V.; Getirana, A.; Rotunno Filho, O. C.; Lakshmi, V.

2016-12-01

In this study, we investigated long-term Terra-MODIS Normalized Difference Vegetation Index (NDVI) response to a recent drought period in Brazil's Southeast (SE) and Northeast (NE) regions between 2012 and 2015. An analysis of precipitation anomaly from 1979 to 2015 suggests a dry period over NE in 2012-2013 and SE in 2014-2015. Through EOF analysis it was possible to note that the first two modes account for 76% of variability and depict the vegetation seasonal cycle. Moreover, the time series of the respective modes show a deviation of NDVI in 2012 when both regions had negative precipitation anomaly. The other EOF modes show a negative trend from 2012 until 2015 mainly in northeastern Brazil in the semiarid region named Caatinga. In order to examine the influence of hydro-meterological variables on vegetation changes, the SVD technique was used to identify coupled patterns between NDVI and precipitation, soil moisture and evapotranspiration. SVD results showed that the highest correlations are achieved between NDVI and precipitation, 0.81 and 0.83, respectively in the first two modes. Although less correlated than precipitation, significant coupling between NDVI and evapotranspiration was found for the second and third modes, the correlation between their expanded coefficients was respectively 0.82 and 0.90.

Worsened physical condition due to climate change contributes to the increasing hypoxia in Chesapeake Bay.

PubMed

Du, Jiabi; Shen, Jian; Park, Kyeong; Wang, Ya Ping; Yu, Xin

2018-07-15

There are increasing concerns about the impact of worsened physical condition on hypoxia in a variety of coastal systems, especially considering the influence of changing climate. In this study, an EOF analysis of the DO data for 1985-2012, a long-term numerical simulation of vertical exchange, and statistical analysis were applied to understand the underlying mechanisms for the variation of DO condition in Chesapeake Bay. Three types of analysis consistently demonstrated that both biological and physical conditions contribute equally to seasonal and interannual variations of the hypoxic condition in Chesapeake Bay. We found the physical condition (vertical exchange+temperature) determines the spatial and seasonal pattern of the hypoxia in Chesapeake Bay. The EOF analysis showed that the first mode, which was highly related to the physical forcings and correlated with the summer hypoxia volume, can be well explained by seasonal and interannual variations of physical variables and biological activities, while the second mode is significantly correlated with the estuarine circulation and river discharge. The weakened vertical exchange and increased water temperature since the 1980s demonstrated a worsened physical condition over the past few decades. Under changing climate (e.g., warming, accelerated sea-level rise, altered precipitation and wind patterns), Chesapeake Bay is likely to experience a worsened physical condition, which will amplify the negative impact of anthropogenic inputs on eutrophication and consequently require more efforts for nutrient reduction to improve the water quality condition in Chesapeake Bay. Copyright © 2018 Elsevier B.V. All rights reserved.

Distinct winter patterns of tropical Pacific convection anomaly and the associated extratropical wave trains in the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Ding, Shuoyi; Chen, Wen; Graf, Hans-F.; Guo, Yuanyuan; Nath, Debashis

2017-11-01

In this paper, distinct patterns of boreal winter convection anomalies over the tropical Pacific and associated wave trains in the extratropics are addressed. The first leading mode (EOF1) of convection anomalies as measured by outgoing longwave radiation demonstrates an east-west oscillation of deep convection with centers over the equatorial central Pacific (CP) and over the tropical western North Pacific and the Maritime Continent. The second leading mode (EOF2) is also a dipole pattern with opposite centers straddling 170°W, possibly modifying EOF1 to some extent. Combining the first two leading modes, five major categories of tropical convection anomalies can be identified for the period 1979/80-2012/13. The comparison between these five categories and the corresponding SST anomaly patterns indicates a nonlinear relationship between convection and SST. The combination of EOF1 and EOF2 with in-phase PCs exhibits an east-west dipole pattern with opposite signs over west of the dateline and the Maritime Continent. The negative phase of the two PCs, named La Niña pattern, induces a negative Pacific/North American—positive North Atlantic Oscillation teleconnection in the extratropics. Approximately opposite responses can be detected in its positive phase, named CP El Niño pattern. The negative PC2 superposing positive PC1, named EP El Niño pattern, shows the strongest convection anomalies with enhanced (depressed) convection over the eastern (western) Pacific and leads to a Tropical/Northern Hemisphere-like teleconnection pattern and an anomalous anticyclone extending from the North Pacific to the North Atlantic. The positive PC2 with neutral PC1, named western CP pattern, shows weakly enhanced convection to the west of the dateline as a response to local SST warming around the dateline. This convection anomaly pattern, although weak, is important and excites a northeastward wave train from the tropics to Greenland, resulting in surface air temperature cooling covering the northeastern North America and warmer and wetter conditions over Western Europe.

[Key factors in the control of electroosmosis with external radial electric field in CE].

PubMed

Zhu, Y; Chen, Y

1999-11-01

Direct control of electroosmosis flow (EOF) by external radial electric field was performed at room temperature using a home-made field-modulated capillary electrophoresis (CE) system. The EOF was monitored at 206 nm by using DMSO as a probe. To apply a radial electric field across the CE capillary wall, the capillary was cased with a wide column. Both of the concentric space and the capillary bore were then filled with an identical running buffer and applied with an axial electric field of 150 V/cm but starting from different levels. All of the tubes used were made of fused silica with polyimide over-coating (from the Yongnian Optical Fiber Work, Hebei, P. R. China). The size of the CE capillaries adopted was 25-100 microns i.d. (375 microns o.d.) x 28.5/45 cm (effective/total length), and that of the casing column 400 microns i.d. x 32 cm. To investigate the fundamentals of the external EOF control when using the flexible fused silica capillaries, various parameters have been inspected such as pH, buffer composition, additives and capillary wall feature etc.. As expected, to well control both of the magnitude and direction of the electroosmosis, the buffer pH should be kept below 4 and the buffer concentration below 50 mmol/L. However, buffers below 1 mmol/L should be avoided because such a diluted running buffer may result in poor CE separation. Weak electrolytes like citric acid, tartaric acid and acetic acid were found to be capable of generating better EOF control than the strong electrolytes such as phosphate and chlorides. This is possibly due to the formation of looser electric double layer with the weak rather than the strong electrolytes. Some wall coatings like calix arene and its derivatives can evidently improve the EOF control even at pH 5. This reveals an exciting way to expend the controllable pH range. In addition, narrow-bore capillaries were demonstrated to be better than wide-bore tubes. Other conditions such as buffer additives and capillary rinse procedure were shown to have only negligible influence on the control.

High storm surge events in Venice and the 11-yr solar cycle

NASA Astrophysics Data System (ADS)

Barriopedro, David; García-Herrera, Ricardo; Lionello, Piero; Pino, Cosimo

2010-05-01

In the last years the Venice lagoon has received much attention as a case of coastal vulnerability, mainly because of relative sea level rise and increase frequency of storm surge events, the so-called "aqua alta", which, particularly during autumn, cause the flooding of the Venice historical city center. Long-term fluctuations in solar activity and large-scale climate patterns have been suggested as feasible factors of flooding variability. This study explores the long-term frequency variability of High Surge Events (HSE) in Venice for the period 1948-2008 and its modulation by the 11-yr solar cycle. A significant decadal variability in the frequency of HSE is found in good correspondence with the 11-yr cycle, solar maxima being associated to a significant increase of the October-November-December HSE frequency. A Storm Surge Pattern (SSP), i.e. the seasonal 1000 hPa height pattern associated to increased frequency of HSE, is identified and found similar to the positive phase of the main variability mode of the regional atmospheric circulation (EOF1). However, further analyses indicate that the increase of HSE in solar maxima cannot be simply explained by a higher recurrence of positive EOF1 phases during high solar years. It rather seems that solar activity modulates the spatial patterns of the atmospheric circulation (EOF) and the favorable conditions for HSE occurrence (SSP). Thus, under solar maxima, the occurrence of HSE is enhanced by the EOF1, namely a large-scale wave train pattern that is symptomatic of storm track paths over northern Europe. Solar minima reveal a substantially different and less robust SSP, consisting of a meridionally oriented dipole with a preferred southward path of storm track activity, which is not associated to any EOF during low solar periods. It is concluded that solar activity plays an indirect role in the frequency of HSE by modulating the spatial patterns of the main modes of atmospheric regional variability, the favorable patterns for HSE occurrence and their mutual relationships, so that constructive interaction between them is enhanced during solar maxima and inhibited in solar minima.

TRMM Fire Algorithm, Product and Applications

NASA Technical Reports Server (NTRS)

Ji, Yi-Min; Stocker, Erich

2003-01-01

Land fires are frequent menaces to human lives and property. They also change the state of the vegetation and contribute to the climate forcing by releasing large amount of aerosols and greenhouse gases into the atmosphere. This paper summarizes methodologies of detecting global land fires from the Tropical Rainfall Measuring Mission (TRMM) Visible Infrared Scanner FIRS) measurements. The TRMM Science Data and Information System (TSDIS) fire products include global images of daily hot spots and monthly fire counts at 0.5 deg. x 0.5 deg. resolution, as well as text fiies that details necessary information of all fire pixels. The information includes date, orbit number, pixel number, local time, solar zenith angle, latitude, longitude, reflectance of visible/near infrared channels, brightness temperatures of infrared channels, as well as background brightness temperatures of infrared channels. These products have been archived since January 1998. The TSDIS fire products are compared with the coincidental European Commission (EC) Joint Research Center (JRC) 1 km AVHRR fire products. Analyses of the TSDIS monthly fire products during the period from 1998 to 2003 manifested seasonal cycles of biomass fires over Southeast Asia, Africa, North America and South America. The data also showed interannual variations associated with the 98/99 ENS0 cycle in Central America and the Indonesian region. In order to understand the variability of global land fires and their effects on the distribution of atmospheric aerosols, statistical methods were applied to the TSDIS fire products as well as to the Total Ozone Mapping Spectrometer (TOMS) aerosol index products for a period of five years from January 1998 to December 2002. The variability of global atmospheric aerosol is consistent with the fire variations over these regions during this period. The correlation between fire count and TOMS aerosol index is about 0.55 for fire pixels in Southeast Asia, Indonesia, and Africa. Parallel statistical analyses such as Empirical Orthogonal Function (EOF) analysis and Singular Spectrum Analysis (SSA) methods were applied to pentad TRMM fire data and TOMS aerosol data. The EOF analyses showed contrast between North and South hemispheres and also inter- continental transitions in Africa and America. EOF and SSA analyses also identified 25-60 day intra-seasonal oscillations that were superimposed on the annual cycles of both fire and aerosol data. The intra-seasonal variability of fires showed similarity of tropical rainfall oscillation modes. The TRMM fire products were also compared to the coincident TRMh4 rainfall and other rainfall products to investigate the interaction between rainfall and fire. The results indicate that the annual, interannual and intraseasonal variability of fire are dominated by global rainfall variations. However, the feedback of fire to the rainfall occurrence at regional scale for certain regions is also evident.

Error Estimation of An Ensemble Statistical Seasonal Precipitation Prediction Model

NASA Technical Reports Server (NTRS)

Shen, Samuel S. P.; Lau, William K. M.; Kim, Kyu-Myong; Li, Gui-Long

2001-01-01

This NASA Technical Memorandum describes an optimal ensemble canonical correlation forecasting model for seasonal precipitation. Each individual forecast is based on the canonical correlation analysis (CCA) in the spectral spaces whose bases are empirical orthogonal functions (EOF). The optimal weights in the ensemble forecasting crucially depend on the mean square error of each individual forecast. An estimate of the mean square error of a CCA prediction is made also using the spectral method. The error is decomposed onto EOFs of the predictand and decreases linearly according to the correlation between the predictor and predictand. Since new CCA scheme is derived for continuous fields of predictor and predictand, an area-factor is automatically included. Thus our model is an improvement of the spectral CCA scheme of Barnett and Preisendorfer. The improvements include (1) the use of area-factor, (2) the estimation of prediction error, and (3) the optimal ensemble of multiple forecasts. The new CCA model is applied to the seasonal forecasting of the United States (US) precipitation field. The predictor is the sea surface temperature (SST). The US Climate Prediction Center's reconstructed SST is used as the predictor's historical data. The US National Center for Environmental Prediction's optimally interpolated precipitation (1951-2000) is used as the predictand's historical data. Our forecast experiments show that the new ensemble canonical correlation scheme renders a reasonable forecasting skill. For example, when using September-October-November SST to predict the next season December-January-February precipitation, the spatial pattern correlation between the observed and predicted are positive in 46 years among the 50 years of experiments. The positive correlations are close to or greater than 0.4 in 29 years, which indicates excellent performance of the forecasting model. The forecasting skill can be further enhanced when several predictors are used.

A discussion of the links between solar variability and high-storm-surge events in Venice

NASA Astrophysics Data System (ADS)

Barriopedro, David; GarcíA-Herrera, Ricardo; Lionello, Piero; Pino, Cosimo

2010-07-01

This study explores the long-term frequency variability of high-surge events (HSEs) in the North Adriatic, the so-called acqua alta, which, particularly during autumn, cause flooding of the historical city center of Venice. The period 1948-2008, when hourly observations of sea level are available, is considered. The frequency of HSEs is correlated with the 11 year solar cycle, solar maxima being associated with a significant increase in the October-November-December HSE frequency. The seasonal geopotential height pattern at 1000 hPa (storm surge pattern; SSP) associated with the increased frequency of HSEs is identified for the whole time period and found to be similar to the positive phase of the main variability mode of the regional atmospheric circulation (empirical orthogonal function 1; EOF1). However, further analysis indicates that solar activity modulates the spatial patterns of the atmospheric circulation (EOF) and the favorable conditions for HSE occurrence (SSP). Under solar maxima, the occurrence of HSEs is enhanced by the main mode of regional atmospheric variability, namely, a large-scale wave train pattern that is symptomatic of storm track paths over northern Europe. Solar minima reveal a substantially different and less robust SSP, consisting of a meridionally oriented dipole with a preferred southward path of storm track activity, which is not associated with any dominant mode of atmospheric variability during low-solar periods. It is concluded that solar activity plays an indirect role in the frequency of HSEs by modulating the spatial patterns of the main modes of atmospheric regional variability, the favorable patterns for HSE occurrence, and their mutual relationships, so that constructive interaction between them is enhanced during solar maxima and inhibited in solar minima.

Statistical downscaling of general-circulation-model- simulated average monthly air temperature to the beginning of flowering of the dandelion (Taraxacum officinale) in Slovenia

NASA Astrophysics Data System (ADS)

Bergant, Klemen; Kajfež-Bogataj, Lučka; Črepinšek, Zalika

2002-02-01

Phenological observations are a valuable source of information for investigating the relationship between climate variation and plant development. Potential climate change in the future will shift the occurrence of phenological phases. Information about future climate conditions is needed in order to estimate this shift. General circulation models (GCM) provide the best information about future climate change. They are able to simulate reliably the most important mean features on a large scale, but they fail on a regional scale because of their low spatial resolution. A common approach to bridging the scale gap is statistical downscaling, which was used to relate the beginning of flowering of Taraxacum officinale in Slovenia with the monthly mean near-surface air temperature for January, February and March in Central Europe. Statistical models were developed and tested with NCAR/NCEP Reanalysis predictor data and EARS predictand data for the period 1960-1999. Prior to developing statistical models, empirical orthogonal function (EOF) analysis was employed on the predictor data. Multiple linear regression was used to relate the beginning of flowering with expansion coefficients of the first three EOF for the Janauary, Febrauary and March air temperatures, and a strong correlation was found between them. Developed statistical models were employed on the results of two GCM (HadCM3 and ECHAM4/OPYC3) to estimate the potential shifts in the beginning of flowering for the periods 1990-2019 and 2020-2049 in comparison with the period 1960-1989. The HadCM3 model predicts, on average, 4 days earlier occurrence and ECHAM4/OPYC3 5 days earlier occurrence of flowering in the period 1990-2019. The analogous results for the period 2020-2049 are a 10- and 11-day earlier occurrence.

Identification of biogeochemical hot spots using time-lapse hydrogeophysics

NASA Astrophysics Data System (ADS)

Franz, T. E.; Loecke, T.; Burgin, A.

2016-12-01

The identification and monitoring of biogeochemical hot spots and hot moments is difficult using point based sampling techniques and sensors. Without proper monitoring and accounting of water, energy, and trace gas fluxes it is difficult to assess the environmental footprint of land management practices. One key limitation is optimal placement of sensors/chambers that adequately capture the point scale fluxes and thus a reasonable integration to landscape scale flux. In this work we present time-lapse hydrogeophysical imaging at an old agricultural field converted into a wetland mitigation bank near Dayton, Ohio. While the wetland was previously instrumented with a network of soil sensors and surface chambers to capture a suite of state variables and fluxes, we hypothesize that time-lapse hydrogeophysical imaging is an underutilized and critical reconnaissance tool for effective network design and landscape scaling. Here we combine the time-lapse hydrogeophysical imagery with the multivariate statistical technique of Empirical Orthogonal Functions (EOF) in order to isolate the spatial and temporal components of the imagery. Comparisons of soil core information (e.g. soil texture, soil carbon) from around the study site and organized within like spatial zones reveal statistically different mean values of soil properties. Moreover, the like spatial zones can be used to identify a finite number of future sampling locations, evaluation of the placement of existing sensors/chambers, upscale/downscale observations, all of which are desirable techniques for commercial use in precision agriculture. Finally, we note that combining the EOF analysis with continuous monitoring from point sensors or remote sensing products may provide a robust statistical framework for scaling observations through time as well as provide appropriate datasets for use in landscape biogeochemical models.

Instantaneous velocity measurement of AC electroosmotic flows by laser induced fluorescence photobleaching anemometer with high temporal resolution

NASA Astrophysics Data System (ADS)

Zhao, Wei; Yang, Fang; Qiao, Rui; Wang, Guiren; Rui Qiao Collaboration

2015-11-01

Understanding the instantaneous response of flows to applied AC electric fields may help understand some unsolved issues in induced-charge electrokinetics and enhance performance of microfluidic devices. Since currently available velocimeters have difficulty in measuring velocity fluctuations with frequency higher than 1 kHz, most experimental studies so far focus only on the average velocity measurement in AC electrokinetic flows. Here, we present measurements of AC electroosmotic flow (AC-EOF) response time in microchannels by a novel velocimeter with submicrometer spatial resolution and microsecond temporal resolution, i.e. laser-induced fluorescence photobleaching anemometer (LIFPA). Several parameters affecting the AC-EOF response time to the applied electric signal were investigated, i.e. channel length, transverse position and solution conductivity. The experimental results show that the EOF response time under a pulsed electric field decreases with the reduction of the microchannel length, distance between the detection position to the wall and the conductivity of the solution. This work could provide a new powerful tool to measure AC electrokinetics and enhance our understanding of AC electrokinetic flows.

Spatial and temporal correlation between beach and wave processes: implications for bar-berm sediment transition

NASA Astrophysics Data System (ADS)

Joevivek, V.; Chandrasekar, N.; Saravanan, S.; Anandakumar, H.; Thanushkodi, K.; Suguna, N.; Jaya, J.

2018-06-01

Investigation of a beach and its wave conditions is highly requisite for understanding the physical processes in a coast. This study composes spatial and temporal correlation between beach and nearshore processes along the extensive sandy beach of Nagapattinam coast, southeast peninsular India. The data collection includes beach profile, wave data, and intertidal sediment samples for 2 years from January 2011 to January 2013. The field data revealed significant variability in beach and wave morphology during the northeast (NE) and southwest (SW) monsoon. However, the beach has been stabilized by the reworking of sediment distribution during the calm period. The changes in grain sorting and longshore sediment transport serve as a clear evidence of the sediment migration that persevered between foreshore and nearshore regions. The Empirical Orthogonal Function (EOF) analysis and Canonical Correlation Analysis (CCA) were utilized to investigate the spatial and temporal linkages between beach and nearshore criterions. The outcome of the multivariate analysis unveiled that the seasonal variations in the wave climate tends to influence the bar-berm sediment transition that is discerned in the coast.

The PPP Simulator: User’s Manual and Report

DTIC Science & Technology

1986-11-01

simulator: Script started on Thu Aug 28 09:16:15 1986 1 ji] -> ppp -d Benchmarks/Par/ccon6.w pau load /a/hprg’fagin/ PPPl /Benchmarks/Par,’concatOP .w Capace...EOF ) putc( c, stdout ) #else if(( fp = fopen("/a/hprg/fagin/ PPPl /notes’, fir" ))!NULL) while(( c = getc(fp)) != EOF ) putc( c, stdout ) #erndif if...hprg/fagin/ PPPl /bitl.d’, fir" ) =NULL) lddsptbl( fp, bi-tbl ); while((--argc > 0) && ((*.+argv)[0]= -I for( s =argv[0]+l; *s!=’\\0’ s++ A -A Aug 18 16

Spatio-temporal water quality mapping from satellite images using geographically and temporally weighted regression

NASA Astrophysics Data System (ADS)

Chu, Hone-Jay; Kong, Shish-Jeng; Chang, Chih-Hua

2018-03-01

The turbidity (TB) of a water body varies with time and space. Water quality is traditionally estimated via linear regression based on satellite images. However, estimating and mapping water quality require a spatio-temporal nonstationary model, while TB mapping necessitates the use of geographically and temporally weighted regression (GTWR) and geographically weighted regression (GWR) models, both of which are more precise than linear regression. Given the temporal nonstationary models for mapping water quality, GTWR offers the best option for estimating regional water quality. Compared with GWR, GTWR provides highly reliable information for water quality mapping, boasts a relatively high goodness of fit, improves the explanation of variance from 44% to 87%, and shows a sufficient space-time explanatory power. The seasonal patterns of TB and the main spatial patterns of TB variability can be identified using the estimated TB maps from GTWR and by conducting an empirical orthogonal function (EOF) analysis.

Variability of the western Galician upwelling system (NW Spain) during an intensively sampled annual cycle. An EOF analysis approach

NASA Astrophysics Data System (ADS)

Herrera, J. L.; Rosón, G.; Varela, R. A.; Piedracoba, S.

2008-07-01

The key features of the western Galician shelf hydrography and dynamics are analyzed on a solid statistical and experimental basis. The results allowed us to gather together information dispersed in previous oceanographic works of the region. Empirical orthogonal functions analysis and a canonical correlation analysis were applied to a high-resolution dataset collected from 47 surveys done on a weekly frequency from May 2001 to May 2002. The main results of these analyses are summarized bellow. Salinity, temperature and the meridional component of the residual current are correlated with the relevant local forcings (the meridional coastal wind component and the continental run-off) and with a remote forcing (the meridional temperature gradient at latitude 37°N). About 80% of the salinity and temperature total variability over the shelf, and 37% of the residual meridional current total variability are explained by two EOFs for each variable. Up to 22% of the temperature total variability and 14% of the residual meridional current total variability is devoted to the set up of cross-shore gradients of the thermohaline properties caused by the wind-induced Ekman transport. Up to 11% and 10%, respectively, is related to the variability of the meridional temperature gradient at the Western Iberian Winter Front. About 30% of the temperature total variability can be explained by the development and erosion of the seasonal thermocline and by the seasonal variability of the thermohaline properties of the central waters. This thermocline presented unexpected low salinity values due to the trapping during spring and summer of the high continental inputs from the River Miño recorded in 2001. The low salinity plumes can be traced on the Galician shelf during almost all the annual cycle; they tend to be extended throughout the entire water column under downwelling conditions and concentrate in the surface layer when upwelling favourable winds blow. Our evidences point to the meridional temperature gradient acting as an important controlling factor of the central waters thermohaline properties and in the development and decay of the Iberian Poleward Current.

Creation of Synthetic Surface Temperature and Precipitation Ensembles Through A Computationally Efficient, Mixed Method Approach

NASA Astrophysics Data System (ADS)

Hartin, C.; Lynch, C.; Kravitz, B.; Link, R. P.; Bond-Lamberty, B. P.

2017-12-01

Typically, uncertainty quantification of internal variability relies on large ensembles of climate model runs under multiple forcing scenarios or perturbations in a parameter space. Computationally efficient, standard pattern scaling techniques only generate one realization and do not capture the complicated dynamics of the climate system (i.e., stochastic variations with a frequency-domain structure). In this study, we generate large ensembles of climate data with spatially and temporally coherent variability across a subselection of Coupled Model Intercomparison Project Phase 5 (CMIP5) models. First, for each CMIP5 model we apply a pattern emulation approach to derive the model response to external forcing. We take all the spatial and temporal variability that isn't explained by the emulator and decompose it into non-physically based structures through use of empirical orthogonal functions (EOFs). Then, we perform a Fourier decomposition of the EOF projection coefficients to capture the input fields' temporal autocorrelation so that our new emulated patterns reproduce the proper timescales of climate response and "memory" in the climate system. Through this 3-step process, we derive computationally efficient climate projections consistent with CMIP5 model trends and modes of variability, which address a number of deficiencies inherent in the ability of pattern scaling to reproduce complex climate model behavior.

Quality evaluation of six bioactive constituents in goji berry based on capillary electrophoresis field amplified sample stacking.

PubMed

Wang, Wei-Feng; Yang, Jun-Li; Shi, Yan-Ping

2018-04-27

Goji berry, fruits of the plant Lycium barbarum L., has long been used as traditional medicine and functional food in China. In this work, a simple and easy-operation on-line concentration capillary electrophoresis (CE) for detection flavonoids in goji berry was developed by coupling of field amplified sample stacking (FASS) with an electroosmotic (EOF) pump driving water removal process. Due to the EOF pump and electrokinetic injection showing different influence on the concentration, the analytes injection condition should be systemically studied. Thereafter, the verification of the analytes injection conditions was achieved using response surface experimental design. Under the optimum conditions, 86-271 folds sensitivity enhancement upon normal capillary zone electrophoresis (CZE, 50 mbar × 5 s) were achieved for six flavonoids, and the detection limits ranged from 0.35 to 1.82 ng/mL; the LOQ ranged from 1.20 to 6.01 ng/mL. Eventually, the proposed method was applied to detect flavonoids in 30 goji berry samples from different habitats of China; and the results indicated that the flavonoids were rich in the eluent of 30-60% methanol, which provided a reference for extraction of goji berry flavonoids. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water exchange between Algeciras Bay and the Strait of Gibraltar: A study based on HF coastal radar

NASA Astrophysics Data System (ADS)

Chioua, J.; Dastis, C.; González, C. J.; Reyes, E.; Mañanes, R.; Ruiz, M. I.; Álvarez, E.; Yanguas, F.; Romero, J.; Álvarez, O.; Bruno, M.

2017-09-01

This study analyses the water mass exchanges at subinertial scale between Algeciras Bay and the adjacent Strait of Gibraltar. The mechanisms triggering this exchange process is investigated with the aid of recently-acquired data on surface currents obtained using a system of HF coastal radars deployed on the eastern side of the Strait, and remotely-sensed images of sea surface temperature (SST) and chlorophyll from the MODIS sensor of the Aqua satellite. HF radar data on surface currents are analyzed by the application of real empirical orthogonal function (EOF) decomposition, which produces three EOF modes explaining more than 70% of the variance of the surface currents at the mouth of the Bay (modes 2, 3, and 6). Mode 2 is related to the fluctuations of the Atlantic Jet in the central zone of the Strait, mainly due to a combined effect of the atmospheric pressure fluctuations in the Western Mediterranean Sea and local wind in the eastern side of the Strait; mode 3 is related to the coastal currents induced by zonal wind forcing on the north-western coast of the Strait and Alboran Sea; and mode 6 seems to be related to water transport induced by winds blowing with a significant north component into and out of the Bay.

FGGE/ERBM tape specification and shipping letter description

NASA Technical Reports Server (NTRS)

Han, D.; Lo, H.

1983-01-01

The Nimbus-7 FGGE/ERBM tape contains 27 ERB parameters which are extracted and reformatted from the Nimbus-7 ERB-MATRIX tape. There are four types of files on a FGGE/ERBM tape: a test file; tape-header file which describes the data set characteristics and the contents of the tape; a grid-descriptor file which contains the information of the ERB scanning channel target number and their associated latitude limits and longitude intervals; and one or more data files. A single end-of-file (EOF) tape mark is written after each file, and two EOF marks are written after the last data file on the tape.

Tradeoff between mixing and transport for electroosmotic flow in heterogeneous microchannels with nonuniform surface potentials.

PubMed

Tian, Fuzhi; Li, Baoming; Kwok, Daniel Y

2005-02-01

Electroosmotic flow (EOF) is a phenomenon associated with the movement of an aqueous solution induced by the application of an electric field in microchannels. The characteristics of EOF depend on the nature of the surface potential, i.e., whether it is uniform or nonuniform. In this paper, a lattice Boltzmann model (LBM) combined with the Poisson-Boltzmann equation is used to simulate flow field in a rectangular microchannel with nonuniform (step change) surface potentials. The simulation results indicate that local circulations can occur near a heterogeneous region with nonuniform surface potentials, in agreement with those by other authors. Largest circulations, which imply a highest mixing efficiency due to convection and short-range diffusion, were found when the average surface potential is zero, regardless of whether the distribution of the heterogeneous patches is symmetric or asymmetric. In this work, we have illustrated that there is a trade-off between the mixing and liquid transport in EOF microfluidics. One should not simply focus on mixing and neglect liquid transport, as performed in the literature. Excellent mixing could lead to a poor transport of electroosmotic flow in microchannels.

North Polar Radiative Flux Variability from 2002 Through 2014

NASA Technical Reports Server (NTRS)

Rutan, David; Rose, Fred; Doelling, David; Kato, Seiji; Smith, Bill, Jr.

2017-01-01

NASA's Clouds and the Earth's Radiant Energy System (CERES) project produces the SYN1Deg data product. SYN1deg provides global, 1deg gridded, hourly estimates of Top of Atmosphere (TOA) (CERES observations and calculations) and atmospheric and surface radiative flux (calculations). Examples of 12 year North Polar averages of some variables are shown to the right. Given recent interest in polar science we focus here on TOA and Surface validation of calculated irradiant fluxes. TOA upward longwave irradiance calculations match the CERES observations well both spatially and temporally with correlations remaining strong through PC 6. Compare SYN1Deg Calculations & Meteorological Teleconnections. TOA reflected shortwave irradiance calculations match the CERES observations well both spatially and temporally with correlations remaining string through PC 7. Comparing SYN1Deg calculations to teleconnection patterns requires expanding the area to 30N for EOF analyses. Correlating the Principal Components of various variables to teleconnection time series indicates which variable is most highly correlated with which teleconnection signal. The tables indicate the Pacific North American Oscillation is most correlated to the OLR EOF 1, and the North American Oscillation is correlated most closely to surface LW flux down EOF 1.

Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

PubMed

Song, Hongjun; Wang, Yi; Pant, Kapil

2013-01-01

This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space.

Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow

PubMed Central

Song, Hongjun; Wang, Yi; Pant, Kapil

2012-01-01

This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space. PMID:23554584

Surface instability of a thin electrolyte film undergoing coupled electroosmotic and electrophoretic flows in a microfluidic channel.

PubMed

Ray, Bahni; Reddy, Puchalapalli Dinesh Sankar; Bandyopadhyay, Dipankar; Joo, Sang W; Sharma, Ashutosh; Qian, Shizhi; Biswas, Gautam

2011-11-01

We consider the stability of a thin liquid film with a free charged surface resting on a solid charged substrate by performing a general Orr-Sommerfeld (O-S) analysis complemented by a long-wave (LW) analysis. An externally applied field generates an electroosmotic flow (EOF) near the solid substrate and an electrophoretic flow (EPF) at the free surface. The EPF retards the EOF when both the surfaces have the same sign of the potential and can even lead to the flow reversal in a part of the film. In conjunction with the hydrodynamic stress, the Maxwell stress is also considered in the problem formulation. The electrokinetic potential at the liquid-air and solid-liquid interfaces is modelled by the Poisson-Boltzmann equation with the Debye-Hückel approximation. The O-S analysis shows a finite-wavenumber shear mode of instability when the inertial forces are strong and an LW interfacial mode of instability in the regime where the viscous force dominates. Interestingly, both the modes are found to form beyond a critical flow rate. The shear (interfacial) mode is found to be dominant when the film is thick (thin), the electric field applied is strong (weak), and the zeta-potentials on the liquid-air and solid-liquid interfaces are high (small). The LW analysis predicts the presence of the interfacial mode, but fails to capture the shear mode. The change in the propagation direction of the interfacial mode with the zeta-potential is predicted by both O-S and LW analyses. The parametric range in which the LW analysis is valid is thus demonstrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spatial and temporal variability of thermohaline properties in the Bay of Koper (northern Adriatic Sea)

NASA Astrophysics Data System (ADS)

Soczka Mandac, Rok; Žagar, Dušan; Faganeli, Jadran

2013-04-01

In this study influence of fresh water discharge on the spatial and temporal variability of thermohaline (TH) conditions is explored for the Bay of Koper (Bay). The Bay is subject to different driving agents: wind stress (bora, sirocco), tidal and seiches effect, buoyancy fluxes, general circulation of the Adriatic Sea and discharge of the Rizana and Badaševica rivers. These rivers have torrential characteristics that are hard to forecast in relation to meteorological events (precipitation). Therefore, during episodic events the spatial and temporal variability of TH properties in the Bay is difficult to determine [1]. Measurements of temperature, salinity and turbidity were conducted monthly on 35 sampling points in the period: June 2011 - December 2012. The data were processed and spatial interpolated with an objective analysis method. Furthermore, empirical orthogonal function analysis (EOF) [2] was applied to investigate spatial and temporal TH variations. Strong horizontal and vertical stratification was observed in the beginning of June 2011 due to high fresh water discharge of the Rizana (31 m3/s) and Badaševica (2 m3/s) rivers. The horizontal gradient (ΔT = 6°C) was noticed near the mouth of the Rizana river. Similar pattern was identified for salinity field on the boundary of the front where the gradient was ΔS = 20 PSU. Vertical temperature gradient was ΔT = 4°C while salinity gradient was ΔS = 18 PSU in the subsurface layer at depth of 3 m. Spatial analysis of the first principal component (86% of the total variance) shows uniform temperature distribution in the surface layer (1m) during the studied period. Furthermore, temporal variability of temperature shows seasonal variation with a minimum in February and maximum in August. This confirms that episodic events have a negligible effect on spatial and temporal variation of temperature in the subsurface layer. Further analysis will include application of EOF on the salinity, density and total suspended matter. Additionally, we will investigate the cross correlations between the above mentioned parameters with singular value decomposition method. Reference: 1. Faganeli, J., Planinc, R., Pezdic, J., Smodis, B., Stegnar, P., and Ogorelec, B. 1991. Marine geology of Gulf of Trieste (northern Adriatic): Geochemical aspects. Marine Geology, 99: 93-108. 2. Glover, M., Jenkins, J., and Doney, S. C. 2011. Modeling methods for marine science. Cambridge University Press, 571 p.

The Low-Level Flow Along the Gulf of California During the North American Monsoon.

NASA Astrophysics Data System (ADS)

Bordoni, S.; Stevens, B.

2007-05-01

Six-years (1999-2004) of QuikSCAT near-surface ocean winds are used to study the flow over the northeast Pacific and the Gulf of California (GoC) during the North American Monsoon season. The wind data show that the onset of the summer season is accompanied by a reversal of the flow along the GoC, with the establishment of a mean southerly wind throughout the gulf. This reversal occurs in late spring and precedes the onset of the monsoonal rains. In the heart of the monsoon season, the time-mean flow is found to be composed of periods of enhanced southerly winds associated with gulf surges. The role that gulf surges play in modulating the GoC mean southerly flow is further explored by performing an EOF analysis of the summertime daily wind anomalies. A gulf surge mode emerges from this analysis as the leading EOF, with the corresponding principal component time series interpretable as an objective index for gulf surge occurrence. This index is used as a reference time series for regression analysis, to explore the relationship between gulf surges and precipitation over the core and marginal regions of the monsoon, as well as the manifestation of these transient events in the large-scale circulation. It is found that, although seemingly mesoscale features confined over the GoC, gulf surges are intimately linked to patterns of large-scale variability of the eastern Pacific ITCZ and greatly contribute to the definition of the northward extent of the monsoonal rains.

Evaluation of atmospheric precipitable water from reanalysis products using homogenized radiosonde observations over China

NASA Astrophysics Data System (ADS)

Zhao, Tianbao; Wang, Juanhuai; Dai, Aiguo

2015-10-01

Many multidecadal atmospheric reanalysis products are available now, but their consistencies and reliability are far from perfect. In this study, atmospheric precipitable water (PW) from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), NCEP/Department of Energy (DOE), Modern Era Retrospective-Analysis for Research and Applications (MERRA), Japanese 55 year Reanalysis (JRA-55), JRA-25, ERA-Interim, ERA-40, Climate Forecast System Reanalysis (CFSR), and 20th Century Reanalysis version 2 is evaluated against homogenized radiosonde observations over China during 1979-2012 (1979-2001 for ERA-40). Results suggest that the PW biases in the reanalyses are within ˜20% for most of northern and eastern China, but the reanalyses underestimate the observed PW by 20%-40% over western China and by ˜60% over the southwestern Tibetan Plateau. The newer-generation reanalyses (e.g., JRA25, JRA55, CFSR, and ERA-Interim) have smaller root-mean-square error than the older-generation ones (NCEP/NCAR, NCEP/DOE, and ERA-40). Most of the reanalyses reproduce well the observed PW climatology and interannual variations over China. However, few reanalyses capture the observed long-term PW changes, primarily because they show spurious wet biases before about 2002. This deficiency results mainly from the discontinuities contained in reanalysis relative humidity fields in the middle-lower troposphere due to the wet bias in older radiosonde records that are assimilated into the reanalyses. An empirical orthogonal function (EOF) analysis revealed two leading modes that represent the long-term PW changes and El Niño-Southern Oscillation-related interannual variations with robust spatial patterns. The reanalysis products, especially the MERRA and JRA-25, roughly capture these EOF modes, which account for over 50% of the total variance. The results show that even during the post-1979 satellite era, discontinuities in radiosonde data can still induce large spurious long-term changes in reanalysis PW and other related fields. Thus, more efforts are needed to remove spurious changes in input data for future long-term reanalyses.

The Relationship Between Sediment Properties and Sedimentation Patterns on a Macrotidal Gravel Beach over a Semi-lunar Tidal Cycle.

NASA Astrophysics Data System (ADS)

Buscombe, D.; Masselink, G.

2007-12-01

Detailed measurements of profile and sediment dynamics have been obtained from a macrotidal gravel barrier beach in southern England. Surface and sub-surface sediment samples, beach profiles, and disturbance depths were taken from the intertidal zone on consecutive low tides over semi-lunar tidal cycles, along with continuous wave and tide measurements. Results from two separate field surveys are presented, representing 26 and 24 consecutive low tides, respectively. A combination of Canonical Correlation Analysis (CCA) and Empirical Orthogonal Function (EOF) analysis was used to identify a number of consistent relationships in morphological and sedimentological variables not readily apparent using ordinary correlations. The disadvantage of such statistical models is that the relationships obtained cannot be expressed in physically meaningful units, which does limit its utility in physical-numerical modelling. However, the results reveal some interesting relationships between gravel beachface sedimentology and morphological change. For example, beachface morphology and sedimentology are more similar at a given spatial location over time than over space (cross-shore) at any individual time. Subsurface sedimentology over the depth of disturbance indicates that the beach step can be traced through the sediment characteristics. Indeed, the study suggests that gravel beachface sedimentology is 'slaved' to morphological change rather than vice-versa; and that the relationship becomes more evident as secondary morphological features develop on the beachface. The results imply that median sediment size and geometric sorting are suitable parameters for detecting such relationships. Strong hysteresis over space was present in the EOF modes associated with the most variance in the data sets, for both sediment size and sorting. Statistically significant relationships were found between the temporal modes of (absolute) size/sorting and net sedimentation associated with the largest variance in the non-decomposed respective data sets. Finally, significant relationships were found between a suite of measured hydrodynamic time-series and pairs of significantly correlated morpho-sedimentary eigenmodes. The techniques used were thus able to objectively demonstrate linear association between morphological and sedimentological change on a gravel beachface over a semi-lunar tidal cycle; and also that simultaneous changes in each could be linearly correlated to hydrodynamic forcing.

Combination of Rivest-Shamir-Adleman Algorithm and End of File Method for Data Security

NASA Astrophysics Data System (ADS)

Rachmawati, Dian; Amalia, Amalia; Elviwani

2018-03-01

Data security is one of the crucial issues in the delivery of information. One of the ways which used to secure the data is by encoding it into something else that is not comprehensible by human beings by using some crypto graphical techniques. The Rivest-Shamir-Adleman (RSA) cryptographic algorithm has been proven robust to secure messages. Since this algorithm uses two different keys (i.e., public key and private key) at the time of encryption and decryption, it is classified as asymmetric cryptography algorithm. Steganography is a method that is used to secure a message by inserting the bits of the message into a larger media such as an image. One of the known steganography methods is End of File (EoF). In this research, the cipher text resulted from the RSA algorithm is compiled into an array form and appended to the end of the image. The result of the EoF is the image which has a line with black gradations under it. This line contains the secret message. This combination of cryptography and steganography in securing the message is expected to increase the security of the message, since the message encryption technique (RSA) is mixed with the data hiding technique (EoF).

Large-Scale Circulation and Climate Variability. Chapter 5

NASA Technical Reports Server (NTRS)

Perlwitz, J.; Knutson, T.; Kossin, J. P.; LeGrande, A. N.

2017-01-01

The causes of regional climate trends cannot be understood without considering the impact of variations in large-scale atmospheric circulation and an assessment of the role of internally generated climate variability. There are contributions to regional climate trends from changes in large-scale latitudinal circulation, which is generally organized into three cells in each hemisphere-Hadley cell, Ferrell cell and Polar cell-and which determines the location of subtropical dry zones and midlatitude jet streams. These circulation cells are expected to shift poleward during warmer periods, which could result in poleward shifts in precipitation patterns, affecting natural ecosystems, agriculture, and water resources. In addition, regional climate can be strongly affected by non-local responses to recurring patterns (or modes) of variability of the atmospheric circulation or the coupled atmosphere-ocean system. These modes of variability represent preferred spatial patterns and their temporal variation. They account for gross features in variance and for teleconnections which describe climate links between geographically separated regions. Modes of variability are often described as a product of a spatial climate pattern and an associated climate index time series that are identified based on statistical methods like Principal Component Analysis (PC analysis), which is also called Empirical Orthogonal Function Analysis (EOF analysis), and cluster analysis.

Comparative evaluation of haematological parameters and erythrocyte membrane stability in pregnant and lactating goats in different seasons of tropical Savannah.

PubMed

Habibu, B; Makun, H J; Yaqub, L S; Buhari, H U; Aluwong, T; Kawu, M U

2017-09-01

Haematological parameters and erythrocyte osmotic fragility (EOF) are commonly used as indicators of health status and erythrocyte membrane integrity. Variations in haematological parameters and EOF in late gestation and early lactation during the cold-dry (CDS), hot-dry (HDS) and rainy (RAS) seasons were studied in sixty (n = 60) Red Sokoto goats (20 goats for each season). The ambient temperatures and temperature-humidity index recorded were higher in the afternoon hours of the HDS and RAS, but lower in the morning hours of the CDS as compared with the thermoneutral zone of goats. Results revealed that the pregnant goats had significantly (P < 0.05) lower PCV and RBC, but higher haemoglobin parameters (Hb, MCH and MCHC) in RAS. Unlike in the pregnant goats, higher (P < 0.05) values of PCV and RBC were observed during the HDS as compared with the CDS and RAS in lactating goats. The EOF was significantly higher during lactation than pregnancy in the CDS and HDS. Similarly, the magnitude of the left shift in fragiligram during the CDS was more marked in pregnant compared with lactating goats. During gestation, the CDS had lower (P < 0.05) EOF than HDS and RAS, with a marked left shift in the fragiligram of both pregnant and lactating goats during the CDS. In conclusion, seasonal variations exist in physiology of erythrocytes of goats during the peri-partum period, with an increase in PCV and RBC, but a decrease in haemoglobin parameters in pregnant compared with lactating goats during the RAS. Erythrocyte stability and membrane integrity were higher in pregnant than lactating goats, and also higher during the CDS than the HDS and RAS, irrespective of reproductive status. This information may be useful in the design of animal breeding and is of value in animal welfare, research, diagnosis and management of haematological conditions during the peri-partum period. Copyright © 2017 Elsevier Inc. All rights reserved.

Detect signals of interdecadal climate variations from an enhanced suite of reconstructed precipitation products since 1850 using the historical station data from Global Historical Climatology Network and the dynamical patterns derived from Global Precipitation Climatology Project

NASA Astrophysics Data System (ADS)

Shen, S. S.

2015-12-01

This presentation describes the detection of interdecadal climate signals in a newly reconstructed precipitation data from 1850-present. Examples are on precipitation signatures of East Asian Monsoon (EAM), Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillations (AMO). The new reconstruction dataset is an enhanced edition of a suite of global precipitation products reconstructed by Spectral Optimal Gridding of Precipitation Version 1.0 (SOGP 1.0). The maximum temporal coverage is 1850-present and the spatial coverage is quasi-global (75S, 75N). This enhanced version has three different temporal resolutions (5-day, monthly, and annual) and two different spatial resolutions (2.5 deg and 5.0 deg). It also has a friendly Graphical User Interface (GUI). SOGP uses a multivariate regression method using an empirical orthogonal function (EOF) expansion. The Global Precipitation Climatology Project (GPCP) precipitation data from 1981-20010 are used to calculate the EOFs. The Global Historical Climatology Network (GHCN) gridded data are used to calculate the regression coefficients for reconstructions. The sampling errors of the reconstruction are analyzed according to the number of EOF modes used in the reconstruction. Our reconstructed 1900-2011 time series of the global average annual precipitation shows a 0.024 (mm/day)/100a trend, which is very close to the trend derived from the mean of 25 models of the CMIP5 (Coupled Model Intercomparison Project Phase 5). Our reconstruction has been validated by GPCP data after 1979. Our reconstruction successfully displays the 1877 El Nino (see the attached figure), which is considered a validation before 1900. Our precipitation products are publically available online, including digital data, precipitation animations, computer codes, readme files, and the user manual. This work is a joint effort of San Diego State University (Sam Shen, Gregori Clarke, Christian Junjinger, Nancy Tafolla, Barbara Sperberg, and Melanie Thorn), UCLA (Yongkang Xue), and University of Maryland (Tom Smith and Phil Arkin) and supported in part by the U.S. National Science Foundation (Awards No. AGS-1419256 and AGS-1015957).

Voltage-Rectified Current and Fluid Flow in Conical Nanopores.

PubMed

Lan, Wen-Jie; Edwards, Martin A; Luo, Long; Perera, Rukshan T; Wu, Xiaojian; Martin, Charles R; White, Henry S

2016-11-15

Ion current rectification (ICR) refers to the asymmetric potential-dependent rate of the passage of solution ions through a nanopore, giving rise to electrical current-voltage characteristics that mimic those of a solid-state electrical diode. Since the discovery of ICR in quartz nanopipettes two decades ago, synthetic nanopores and nanochannels of various geometries, fabricated in membranes and on wafers, have been extensively investigated to understand fundamental aspects of ion transport in highly confined geometries. It is now generally accepted that ICR requires an asymmetric electrical double layer within the nanopore, producing an accumulation or depletion of charge-carrying ions at opposite voltage polarities. Our research groups have recently explored how the voltage-dependent ion distributions and ICR within nanopores can induce novel nanoscale flow phenomena that have applications in understanding ionics in porous materials used in energy storage devices, chemical sensing, and low-cost electrical pumping of fluids. In this Account, we review our most recent investigations on this topic, based on experiments using conical nanopores (10-300 nm tip opening) fabricated in thin glass, mica, and polymer membranes. Measurable fluid flow in nanopores can be induced either using external pressure forces, electrically via electroosmotic forces, or by a combination of these two forces. We demonstrate that pressure-driven flow can greatly alter the electrical properties of nanopores and, vice versa, that the nonlinear electrical properties of conical nanopores can impart novel and useful flow phenomena. Electroosmotic flow (EOF), which depends on the magnitude of the ion fluxes within the double layer of the nanopore, is strongly coupled to the accumulation/depletion of ions. Thus, the same underlying cause of ICR also leads to EOF rectification, i.e., unequal flows occurring for the same voltage but opposite polarities. EOF rectification can be used to electrically pump fluids with very precise control across membranes containing conical pores via the application of a symmetric sinusoidal voltage. The combination of pressure and asymmetric EOF can also provide a means to generate new nanopore electrical behaviors, including negative differential resistance (NDR), in which the current through a conical pore decreases with increasing driving force (applied voltage), similar to solid-state tunnel diodes. NDR results from a positive feedback mechanism between the ion distributions and EOF, yielding a true bistability in both fluid flow and electrical current at a critical applied voltage. Nanopore-based NDR is extremely sensitive to the surface charge near the nanopore opening, suggesting possible applications in chemical sensing.

Chiral separation of β-blockers by MEEKC using neutral microemulsion: Analysis of separation mechanism and further elucidation of resolution equation.

PubMed

Hu, Shao-Qiang; Lü, Wen-Juan; Ma, Yan-Hua; Hu, Qin; Dong, Li-Jun; Chen, Xing-Guo

2013-01-01

Based on the investigation of the effect of microemulsion charge on the chiral separation, a new chiral separation method with MEEKC employing neutral microemulsion was established. The method used a microemulsion containing 3.0% (w/v) neutral surfactant Tween 20 and 0.8% (w/v, 30 mM) dibutyl l-tartrate in 40 mM sodium tetraborate buffer to separate the enantiomers of β-blockers. The effect of major parameters on the chiral separation was investigated. The applied voltage had little effect on the resolution, but the chiral separation could be improved by suppressing the EOF. Nine racemic β-blockers obtained relatively good enantioseparation after appropriate concentrations of tetradecyl trimethyl ammonium bromide were added into the microemulsion to suppress the EOF. These results were explained based on the analysis of the separation mechanism of the method and deduced separation equations. The resolution equation of the method was further elucidated. It was found that the fourth term in the resolution equation, an additional term compared to the conventional resolution equation for column chromatography, represents the ratio of the relative movement distance between the analyte and microemulsion droplets relative to the effective capillary length. It can be regarded as a correction for the effective capillary length. These findings are significant for the development of the theory of MEEKC and the development of new chiral MEEKC method. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Contrasting ENSO types with novel satellite derived ocean phytoplankton biomass

NASA Astrophysics Data System (ADS)

Sharma, P.; Singh, A. M.; Marinov, I.; Kostadinov, T. S.

2016-12-01

Observed variations in community structure and biogeochemical processes in the tropics and the North Atlantic have been linked, in the first order, to the El Niño Southern Oscillation phenomenon (e.g., Bates, 2001; Karl et al., 2001; Di Lorenzo et al., 2010; Di Lorenzo et al., 2013). Current significant technical advances have allowed for the retrieval of biological data from the optical properties of the water via satellite ocean color remote sensing, providing an opportunity for quantifying the relationships between biological and climate indices. Studies have focused in-depth on contrasting flavors of the ENSO types with various physical (e.g., Singh et al. 2011; Turk et al. 2011) and biological (e.g., Radenac et al. 2012) indices. Here, we analyze the impact of different ENSO types on biology via analysis of recently-derived backscattering-based biomass separated into size-groups (Kostadinov et al. 2010, 2016) over the 17-year (1997-2013). We further contrast the responses of biomass with those of chlorophyll (Chl) and particulate inorganic carbon (PIC). We analyze the complex spatial differences in both physical (SST, mixed layer depth, winds) and biological (Chl, total and size-partitioned biomass) variability across the Pacific warm pool and equatorial tongue via simple EOF, combined regression-EOF and Agglomerative Hierarchical Clustering (AHC) analysis. The interannual variability in the physical and biological fields show clear signatures of the Niño cold-tongue (NCT) and Niño warm pool (NWP). Possible mechanisms responsible for these signatures are discussed.

Evaluation of Atmospheric Precipitable Water from Reanalysis Products Using Homogenized Radiosonde Observations over China

NASA Astrophysics Data System (ADS)

Zhao, T.; Wang, J.; Dai, A.

2015-12-01

Many multi-decadal atmospheric reanalysis products are avialable now, but their consistencies and reliability are far from perfect. In this study, atmospheric precipitable water (PW) from the NCEP/NCAR, NCEP/DOE, MERRA, JRA-55, JRA-25, ERA-Interim, ERA-40, CFSR and 20CR reanalyses is evaluated against homogenized radiosonde observations over China during 1979-2012 (1979-2001 for ERA-40). Results suggest that the PW biases in the reanalyses are within ˜20% for most of northern and eastern China, but the reanalyses underestimate the observed PW by 20%-40% over western China, and by ˜60% over the southwestern Tibetan Plateau. The newer-generation reanalyses (e.g., JRA25, JRA55, CFSR and ERA-Interim) have smaller root-mean-square error (RMSE) than the older-generation ones (NCEP/NCAR, NCEP/DOE and ERA-40). Most of the reanalyses reproduce well the observed PW climatology and interannual variations over China. However, few reanalyses capture the observed long-term PW changes, primarily because they show spurious wet biases before about 2002. This deficiency results mainly from the discontinuities contained in reanalysis RH fields in the mid-lower troposphere due to the wet bias in older radiosonde records that are assimilated into the reanalyses. An empirical orthogonal function (EOF) analysis revealed two leading modes that represent the long-term PW changes and ENSO-related interannual variations with robust spatial patterns. The reanalysis products, especially the MERRA and JRA-25, roughly capture these EOF modes, which account for over 50% of the total variance. The results show that even during the post-1979 satellite era, discontinuities in radiosonde data can still induce large spurious long-term changes in reanalysis PW and other related fields. Thus, more efforts are needed to remove spurious changes in input data for future long-term reanlayses.

Prediction of rainfall anomalies during the dry to wet transition season over the Southern Amazonia using machine learning tools

NASA Astrophysics Data System (ADS)

Shan, X.; Zhang, K.; Zhuang, Y.; Fu, R.; Hong, Y.

2017-12-01

Seasonal prediction of rainfall during the dry-to-wet transition season in austral spring (September-November) over southern Amazonia is central for improving planting crops and fire mitigation in that region. Previous studies have identified the key large-scale atmospheric dynamic and thermodynamics pre-conditions during the dry season (June-August) that influence the rainfall anomalies during the dry to wet transition season over Southern Amazonia. Based on these key pre-conditions during dry season, we have evaluated several statistical models and developed a Neural Network based statistical prediction system to predict rainfall during the dry to wet transition for Southern Amazonia (5-15°S, 50-70°W). Multivariate Empirical Orthogonal Function (EOF) Analysis is applied to the following four fields during JJA from the ECMWF Reanalysis (ERA-Interim) spanning from year 1979 to 2015: geopotential height at 200 hPa, surface relative humidity, convective inhibition energy (CIN) index and convective available potential energy (CAPE), to filter out noise and highlight the most coherent spatial and temporal variations. The first 10 EOF modes are retained for inputs to the statistical models, accounting for at least 70% of the total variance in the predictor fields. We have tested several linear and non-linear statistical methods. While the regularized Ridge Regression and Lasso Regression can generally capture the spatial pattern and magnitude of rainfall anomalies, we found that that Neural Network performs best with an accuracy greater than 80%, as expected from the non-linear dependence of the rainfall on the large-scale atmospheric thermodynamic conditions and circulation. Further tests of various prediction skill metrics and hindcasts also suggest this Neural Network prediction approach can significantly improve seasonal prediction skill than the dynamic predictions and regression based statistical predictions. Thus, this statistical prediction system could have shown potential to improve real-time seasonal rainfall predictions in the future.

Potential Predictability and Prediction Skill for Southern Peru Summertime Rainfall

NASA Astrophysics Data System (ADS)

WU, S.; Notaro, M.; Vavrus, S. J.; Mortensen, E.; Block, P. J.; Montgomery, R. J.; De Pierola, J. N.; Sanchez, C.

2016-12-01

The central Andes receive over 50% of annual climatological rainfall during the short period of January-March. This summertime rainfall exhibits strong interannual and decadal variability, including severe drought events that incur devastating societal impacts and cause agricultural communities and mining facilities to compete for limited water resources. An improved seasonal prediction skill of summertime rainfall would aid in water resource planning and allocation across the water-limited southern Peru. While various underlying mechanisms have been proposed by past studies for the drivers of interannual variability in summertime rainfall across southern Peru, such as the El Niño-Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), and extratropical forcings, operational forecasts continue to be largely based on rudimentary ENSO-based indices, such as NINO3.4, justifying further exploration of predictive skill. In order to bridge this gap between the understanding of driving mechanisms and the operational forecast, we performed systematic studies on the predictability and prediction skill of southern Peru summertime rainfall by constructing statistical forecast models using best available weather station and reanalysis datasets. At first, by assuming the first two empirical orthogonal functions (EOFs) of summertime rainfall are predictable, the potential predictability skill was evaluated for southern Peru. Then, we constructed a simple regression model, based on the time series of tropical Pacific sea-surface temperatures (SSTs), and a more advanced Linear Inverse Model (LIM), based on the EOFs of tropical ocean SSTs and large-scale atmosphere variables from reanalysis. Our results show that the LIM model consistently outperforms the more rudimentary regression models on the forecast skill of domain averaged precipitation index and individual station indices. The improvement of forecast correlation skill ranges from 10% to over 200% for different stations. Further analysis shows that this advantage of LIM is likely to arise from its representation of local zonal winds and the position of Intertropical Convergence Zone (ITCZ).

Dust sources and atmospheric circulation in concert controlling Saharan dust emission and transport towards the Western Mediterranean Basin

NASA Astrophysics Data System (ADS)

Schepanski, Kerstin; Mallet, Marc; Heinold, Bernd; Ulrich, Max

2017-04-01

Dust transported from north African source regions towards Europe is a ubiquitous phenomenon in the Mediterranean region, a geographic region that is in part densely populated. Besides its impacts on the atmospheric radiation budget, dust suspended in the atmosphere results in reduced air quality, which is generally sensed as a reduction in quality of life. Furthermore, the exposure to dust aerosols enhances the prevalence of respiratory diseases, which reduces the general human wellbeing, and ultimately results in an increased loss of working hours due to illness and hospitalization rates. Characteristics of the atmospheric dust life cycle that determine dust transport will be presented with focus on the ChArMEx special observation period in June and July 2013 using the atmosphere-dust model COSMO-MUSCAT (COSMO: Consortium for Small-scale MOdeling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Modes of atmospheric circulation were identified from empirical orthogonal function (EOF) analysis of the geopotential height at 850 hPa for summer 2013 and compared to EOFs calculated from 1979-2015 ERA-Interim reanalysis. Generally, two different phases were identified. They are related to the eastward propagation of the subtropical ridge into the Mediterranean basin, the position of the Saharan heat low, and the predominant Iberian heat low. The relation of these centres of action illustrates a dipole pattern for enhanced (reduced) dust emission fluxes, stronger (weaker) meridional dust transport, and consequent increase (decrease) atmospheric dust concentrations and deposition fluxes. In concert, the results from this study aim at illustrating the relevance of knowing the dust source locations in concert with the atmospheric circulation. Ultimately, this study addresses the question of what is finally transported towards the Mediterranean basin and Europe from which source regions - and fostered by which atmospheric circulation pattern. Outcomes from this study contribute to the understanding of varying atmospheric mineral dust contributions to the aerosol burden affecting populated areas around Europe.

CM-DataONE: A Framework for collaborative analysis of climate model output

NASA Astrophysics Data System (ADS)

Xu, Hao; Bai, Yuqi; Li, Sha; Dong, Wenhao; Huang, Wenyu; Xu, Shiming; Lin, Yanluan; Wang, Bin

2015-04-01

CM-DataONE is a distributed collaborative analysis framework for climate model data which aims to break through the data access barriers of increasing file size and to accelerate research process. As data size involved in project such as the fifth Coupled Model Intercomparison Project (CMIP5) has reached petabytes, conventional methods for analysis and diagnosis of model outputs have been rather time-consuming and redundant. CM-DataONE is developed for data publishers and researchers from relevant areas. It can enable easy access to distributed data and provide extensible analysis functions based on tools such as NCAR Command Language, NetCDF Operators (NCO) and Climate Data Operators (CDO). CM-DataONE can be easily installed, configured, and maintained. The main web application has two separate parts which communicate with each other through APIs based on HTTP protocol. The analytic server is designed to be installed in each data node while a data portal can be configured anywhere and connect to a nearest node. Functions such as data query, analytic task submission, status monitoring, visualization and product downloading are provided to end users by data portal. Data conform to CMIP5 Model Output Format in each peer node can be scanned by the server and mapped to a global information database. A scheduler included in the server is responsible for task decomposition, distribution and consolidation. Analysis functions are always executed where data locate. Analysis function package included in the server has provided commonly used functions such as EOF analysis, trend analysis and time series. Functions are coupled with data by XML descriptions and can be easily extended. Various types of results can be obtained by users for further studies. This framework has significantly decreased the amount of data to be transmitted and improved efficiency in model intercomparison jobs by supporting online analysis and multi-node collaboration. To end users, data query is therefore accelerated and the size of data to be downloaded is reduced. Methodology can be easily shared among scientists, avoiding unnecessary replication. Currently, a prototype of CM-DataONE has been deployed on two data nodes of Tsinghua University.

Monitoring Lake Victoria Water Quality from Space: Opportunities for Strengthening Trans-boundary Information Sharing for Effective Resource Management

NASA Astrophysics Data System (ADS)

Mugo, R. M.; Korme, T.; Farah, H.; Nyaga, J. W.; Irwin, D.; Flores, A.; Limaye, A. S.; Artis, G.

2014-12-01

Lake Victoria (LV) is an important freshwater resource in East Africa, covering 68,800 km2, and a catchment that spans 193,000km2. It is an important source of food, energy, drinking and irrigation water, transport and a repository for agricultural, human and industrial wastes generated from its catchment. For such a lake, and a catchment transcending 5 international boundaries, collecting data to guide informed decision making is a hard task. Remote sensing is currently the only tool capable of providing information on environmental changes at high spatio-temporal scales. To address the problem of information availability for LV, we tackled two objectives; (1) we analyzed water quality parameters retrieved from MODIS data, and (2) assessed land cover changes in the catchment area using Landsat data. We used L1A MODIS-Aqua data to retrieve lake surface temperature (LST), total suspended matter (TSM), chlorophyll-a (CHLa) and diffuse attenuation coefficient (KD490) in four temporal periods i.e. daily, weekly, monthly and seasonal scales. An Empirical Orthogonal Function (EOF) analysis was done on monthly data. An analysis of land cover change was done using Landsat data for 3 epochs in order to assess if land degradation contributes to water quality changes. Our results indicate that MODIS-Aqua data provides synoptic views of water quality changes in LV at different temporal scales. The Winam Gulf in Kenya, the shores of Jinja town in Uganda, as well as the Mwanza region in Tanzania represent water quality hotspots due to their relatively high TSM and CHLa concentrations. High levels of KD490 in these areas would also indicate high turbidity and thus low light penetration due to the presence of suspended matter, algal blooms, and/or submerged vegetation. The EOF analysis underscores the areas where LST and water color variability are more significant. The changes can be associated with corresponding land use changes in the catchment, where for instance wetlands are converted to croplands. On-going dissemination of our findings together with capacity building efforts with the three main fishery and research institutions working in the lake, will enable informed decision making for the water management of LV. Enhanced capacity in trans-boundary water resources research is critical for successful decision making.

10Be in late deglacial climate simulated by ECHAM5-HAM - Part 2: Isolating the solar signal from 10Be deposition

NASA Astrophysics Data System (ADS)

Heikkilä, U.; Shi, X.; Phipps, S. J.; Smith, A. M.

2013-10-01

This study investigates the effect of deglacial climate on the deposition of the solar proxy 10Be globally, and at two specific locations, the GRIP site at Summit, Central Greenland, and the Law Dome site in coastal Antarctica. The deglacial climate is represented by three 30 yr time slice simulations of 10 000 BP (years before present = 1950 CE), 11 000 BP and 12 000 BP, compared with a preindustrial control simulation. The model used is the ECHAM5-HAM atmospheric aerosol-climate model, driven with sea surface temperatures and sea ice cover simulated using the CSIRO Mk3L coupled climate system model. The focus is on isolating the 10Be production signal, driven by solar variability, from the weather or climate driven noise in the 10Be deposition flux during different stages of climate. The production signal varies on lower frequencies, dominated by the 11yr solar cycle within the 30 yr time scale of these experiments. The climatic noise is of higher frequencies. We first apply empirical orthogonal functions (EOF) analysis to global 10Be deposition on the annual scale and find that the first principal component, consisting of the spatial pattern of mean 10Be deposition and the temporally varying solar signal, explains 64% of the variability. The following principal components are closely related to those of precipitation. Then, we apply ensemble empirical decomposition (EEMD) analysis on the time series of 10Be deposition at GRIP and at Law Dome, which is an effective method for adaptively decomposing the time series into different frequency components. The low frequency components and the long term trend represent production and have reduced noise compared to the entire frequency spectrum of the deposition. The high frequency components represent climate driven noise related to the seasonal cycle of e.g. precipitation and are closely connected to high frequencies of precipitation. These results firstly show that the 10Be atmospheric production signal is preserved in the deposition flux to surface even during climates very different from today's both in global data and at two specific locations. Secondly, noise can be effectively reduced from 10Be deposition data by simply applying the EOF analysis in the case of a reasonably large number of available data sets, or by decomposing the individual data sets to filter out high-frequency fluctuations.

Validation Test Report for the Improved Synthetic Ocean Profile (ISOP) System, Part I: Synthetic Profile Methods and Algorithm

DTIC Science & Technology

2013-03-15

methods as those used for constructing the Generalized Digital Environmental Model ( GDEM ) version 4 (Carnes, Helber, et al. 2010). The purpose of...in the EOF analysis, which is described in Sections 4.2. 1 and 5.2.3. The primary difference between the ISOP climatology and GDEM is that ISOP only...uses paired profiles of T and S whereas GDEM uses all T profiles available. Paired profiles of T and S are required for ISOP because the T and S co

Electroosmotic flow hysteresis for dissimilar ionic solutions

PubMed Central

Lim, An Eng; Lam, Yee Cheong

2015-01-01

Electroosmotic flow (EOF) with two or more fluids is commonly encountered in various microfluidics applications. However, no investigation has hitherto been conducted to investigate the hysteretic or flow direction-dependent behavior during the displacement flow of solutions with dissimilar ionic species. In this investigation, electroosmotic displacement flow involving dissimilar ionic solutions was studied experimentally through a current monitoring method and numerically through finite element simulations. The flow hysteresis can be characterized by the turning and displacement times; turning time refers to the abrupt gradient change of current-time curve while displacement time is the time for one solution to completely displace the other solution. Both experimental and simulation results illustrate that the turning and displacement times for a particular solution pair can be directional-dependent, indicating that the flow conditions in the microchannel are not the same in the two different flow directions. The mechanics of EOF hysteresis was elucidated through the theoretical model which includes the ionic mobility of each species, a major governing parameter. Two distinct mechanics have been identified as the causes for the EOF hysteresis involving dissimilar ionic solutions: the widening/sharpening effect of interfacial region between the two solutions and the difference in ion concentration distributions (and thus average zeta potentials) in different flow directions. The outcome of this investigation contributes to the fundamental understanding of flow behavior in microfluidic systems involving solution pair with dissimilar ionic species. PMID:25945139

Characterization of the startup transient electrokinetic flow in rectangular channels of arbitrary dimensions, zeta potential distribution, and time-varying pressure gradient.

PubMed

Miller, Andrew; Villegas, Arturo; Diez, F Javier

2015-03-01

The solution to the startup transient EOF in an arbitrary rectangular microchannel is derived analytically and validated experimentally. This full 2D transient solution describes the evolution of the flow through five distinct periods until reaching a final steady state. The derived analytical velocity solution is validated experimentally for different channel sizes and aspect ratios under time-varying pressure gradients. The experiments used a time resolved micro particle image velocimetry technique to calculate the startup transient velocity profiles. The measurements captured the effect of time-varying pressure gradient fields derived in the analytical solutions. This is tested by using small reservoirs at both ends of the channel which allowed a time-varying pressure gradient to develop with a time scale on the order of the transient EOF. Results showed that under these common conditions, the effect of the pressure build up in the reservoirs on the temporal development of the transient startup EOF in the channels cannot be neglected. The measurements also captured the analytical predictions for channel walls made of different materials (i.e., zeta potentials). This was tested in channels that had three PDMS and one quartz wall, resulting in a flow with an asymmetric velocity profile due to variations in the zeta potential between the walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evanescent-wave particle velocimetry measurements of zeta-potentials in fused-silica microchannels.

PubMed

Cevheri, Necmettin; Yoda, Minami

2013-07-01

The wall ζ-potential ζ(w), the potential at the shear plane of the electric double layer, depends on the properties of the BGE solution such as the valence and type of electrolyte, the pH and the ionic strength. Most of the methods estimate ζ(w) from measurements of the EOF velocity magnitude ueo , usually spatially averaged over the entire capillary. In these initial studies, evanescent-wave particle velocimetry was used to measure ueo in steady EOF for a variety of monovalent aqueous solutions to evaluate the effect of small amounts of divalent cations, as well as the pH and ionic strength of BGE solutions. In brief, the magnitude of the EOF velocity of NaCl-NaOH and borate buffer-NaOH solutions was estimated from the measured velocities of radius α = 104 nm fluorescent polystyrene particles in 33 μm fused-silica microchannels. The particle ζ-potentials were measured separately using laser-Doppler micro-electrophoresis; ζ(w) was then determined from ueo. The results suggest that evanescent-wave particle velocimetry can be used to estimate ζ(w) for a variety of BGE solutions, and that it can be used in the future to estimate local wall ζ-potential, and hence spatial variations in ζ(w). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hyperspectral retrieval of surface reflectances: A new scheme

NASA Astrophysics Data System (ADS)

Thelen, Jean-Claude; Havemann, Stephan

2013-05-01

Here, we present a new prototype algorithm for the simultaneous retrieval of the atmospheric profiles (temperature, humidity, ozone and aerosol) and the surface reflectance from hyperspectral radiance measurements obtained from air/space borne, hyperspectral imagers. The new scheme, proposed here, consists of a fast radiative transfer code, based on empirical orthogonal functions (EOFs), in conjunction with a 1D-Var retrieval scheme. The inclusion of an 'exact' scattering code based on spherical harmonics, allows for an accurate treatment of Rayleigh scattering and scattering by aerosols, water droplets and ice-crystals, thus making it possible to also retrieve cloud and aerosol optical properties, although here we will concentrate on non-cloudy scenes.

Recruitment success of different fish stocks in the North Sea in relation to climate variability

NASA Astrophysics Data System (ADS)

Dippner, Joachim W.

1997-09-01

Long-term data of year class strengths of different commercially harvested fish stocks based on a virtual population analysis (VPA) are available from ICES. The anomalies of these long-term data sets of year class strength are analyzed using Empirical Orthogonal Functions (EOFs) and are related to climate variability: the anomalies of the sea surface temperature (SST) in the northern North Sea and the North Atlantic Oscillation (NAO) index. A Canonical Correlation Analysis (CCA) between the leading eigenmodes is performed. The results suggest that the variability in the fish recruitment of western mackerel and three gadoids, namely North Sea cod, North Sea saithe, and North Sea whiting is highly correlated to the variability of the North Sea SST which is directly influenced by the NAO. For North Sea haddock and herring no meaningful correlation exists to North Sea SST and NAO. The results allow the conclusion that is seems possible to predict long-term changes in the fish recruitment from climate change scenarios for North Sea cod, North Sea saithe and western mackerel. Furthermore, the results indicate the possibility of recruitment failure for North Sea cod, North Sea whiting, and western mackerel in the case of global warming.

Surface circulation in the Strait of Gibraltar: a comparison study between HF radar and high resolution model data.

NASA Astrophysics Data System (ADS)

Soto-Navarro, Javier; Lorente, Pablo; Álvarez-Fanjul, Enrique; Ruiz-Gil de la Serna, M. Isabel

2015-04-01

Surface currents from the HF radar system deployed by Puertos del Estado (PdE) at the Strait of Gibraltar and an operational high resolution configuration of the MIT global circulation model, implemented in the strait area in the frame of the SAMPA project, have been analyzed and compared in the period February 2013 - September 2014. The comparison have been carried out in the time and frequency domains, by statistical a geophysical (tide ellipses, wind forcing, EOF) methods. Results show good agreement between both current fields in the strait axis, with correlation around 0.6 (reaching 0.9 in the low frequency band). Higher discrepancies are found in the boundaries of the domain, due to the differences in the meridional components, likely related to the sparser and less accurate radar measurements in these areas. Rotary spectral analysis show a very good agreement between both systems, which is reflected in a very similar and realistic representation of the main tide constituents (M2, S2 and K1). The wind forced circulation pattern, of special interest in the mouth of the Bay of Algeciras, is also precisely represented by radar and model. Finally, the spatial patterns of the first four EOF modes of both fields are rather close, reinforcing the previous results. As conclusion, the analysis points out the proper representation of the surface circulation of the area performed by the PdE HF radar system and the SAMPA model. However, weak and strong points are found in both, stressing the importance of having two complementary tools in the area.

The Impact of a Submaximal Level of Exercise on Balance Performance in Older Persons

PubMed Central

2014-01-01

Objective. The purpose of this study was to determine the impact of a submaximal level of exercise on balance performance under a variety of conditions. Material and Method. Thirteen community-dwelling older persons with intact foot sensation (age = 66.69 ± 8.17 years, BMI = 24.65 ± 4.08 kg/m2, female, n = 6) volunteered to participate. Subjects' balance performances were measured using the Modified Clinical Test of Sensory Integration of Balance (mCTSIB) at baseline and after test, under four conditions of stance: (1) eyes-opened firm-surface (EOF), (2) eyes-closed firm-surface (ECF), (3) eyes-opened soft-surface (EOS), and (4) eyes-closed soft-surface (ECS). The 6-minute walk test (6MWT) protocol was used to induce the submaximal level of exercise. Data was analyzed using the Wilcoxon Signed-Rank Test. Results. Balance changes during EOF (z = 0.00, P = 1.00) and ECF (z = −1.342, P = 0.180) were not significant. However, balance changes during EOS (z = −2.314, P = 0.021) and ECS (z = −3.089, P = 0.02) were significantly dropped after the 6MWT. Conclusion. A submaximal level of exercise may influence sensory integration that in turn affects balance performance, particularly on an unstable surface. Rehabilitation should focus on designing intervention that may improve sensory integration among older individuals with balance deterioration in order to encourage functional activities. PMID:25383386

DOE Office of Scientific and Technical Information (OSTI.GOV)

W. C. Adams

The U.S. Nuclear Regulatory Commission (NRC) requested that the Oak Ridge Institute for Science and Education (ORISE) perform a confirmatory survey on the Emergency Operations Facility (EOF) at the Connecticut Yankee Haddam Neck Plant (HNP) in Haddam, Connecticut

Directional flow induced by synchronized longitudinal and zeta-potential controlling AC-electrical fields.

PubMed

van der Wouden, E J; Hermes, D C; Gardeniers, J G E; van den Berg, A

2006-10-01

Electroosmotic flow (EOF) in a microchannel can be controlled by electronic control of the surface charge using an electrode embedded in the wall of the channel. By setting a voltage to the electrode, the zeta-potential at the wall can be changed locally. Thus, the electrode acts as a "gate" for liquid flow, in analogy with a gate in a field-effect transistor. In this paper we will show three aspects of a Field Effect Flow Control (FEFC) structure. We demonstrate the induction of directional flow by the synchronized switching of the gate potential with the channel axial potential. The advantage of this procedure is that potential gas formation by electrolysis at the electrodes that provide the axial electric field is suppressed at sufficiently large switching frequencies, while the direction and magnitude of the EOF can be maintained. Furthermore we will give an analysis of the time constants involved in the charging of the insulator, and thus the switching of the zeta potential, in order to predict the maximum operating frequency. For this purpose an equivalent electrical circuit is presented and analyzed. It is shown that in order to accurately describe the charging dynamics and pH dependency the traditionally used three capacitor model should be expanded with an element describing the buffer capacitance of the silica wall surface.

Insight into the stability of poly(diallydimethylammoniumchloride) and polybrene poly cationic coatings in capillary electrophoresis.

PubMed

Pei, Lei; Lucy, Charles A

2014-10-24

Polycationic polymers are widely used in capillary electrophoresis (CE) as surface coatings to prevent protein adsorption and control electroosmotic flow (EOF). Such semi-permanent coatings are formed by flushing the capillary with a quaternary amine-based polymer such as poly(diallydimethylammonium chloride) (PDADMAC) or polybrene. Compared to covalent capillary coatings, the claimed advantages of adsorptive polycation coatings are their simple preparation and that they are not limited to the pH 2-8 range as are covalent coatings. However, while the latter is commonly claimed, few studies have demonstrated the stability of polycationic coatings at extreme pH. Herein PDADMAC and polybrene are studied as model cationic coatings. PDADMAC with higher molecular weight (M.W.) demonstrated higher EOF stability at pH 9.5, with PDADMAC of M.W. less than 200,000 being unstable at pH 9.5. X-ray photoelectron spectroscopy (XPS) shows that the quaternary amines of PDADMAC and polybrene were slowly converted to tertiary amines in alkaline solution and more rapidly when adsorbed on a silica surface. The degraded polycation deprotonated at pH >7, resulting in loss of polymer from the surface and diminishing EOF. Successive multiple ionic layer (SMIL) coatings show greater alkaline stability by distancing the polycation from the surface. Separations of inorganic anions at pH 9.5 illustrate the degradation behavior and enhanced stability of higher M.W. polycationic coatings. Copyright © 2014 Elsevier B.V. All rights reserved.

Erythrocyte osmotic fragility and general health status of adolescent Sprague Dawley rats supplemented with Hibiscus sabdariffa aqueous calyx extracts as neonates followed by a high-fructose diet post-weaning.

PubMed

Ibrahim, K G; Lembede, B W; Chivandi, E; Erlwanger, K

2018-02-01

High-fructose diets (HFD) can cause oxidative damage to tissues including erythrocyte cell membranes. Hibiscus sabdariffa (HS) has protective antioxidant properties. Rats were used to investigate whether the consumption of HS by neonates would result in long-term effects on their erythrocyte osmotic fragility (EOF) and general health when later fed a high-fructose diet post-weaning through adolescence. Eighty of four-day-old Sprague Dawley rat pups were divided randomly into three treatment groups. The controls (n = 27) received distilled water at 10 ml/kg b. w, while the other groups received either 50 mg/kg (n = 28) or 500 mg/kg (n = 25) of an HS aqueous calyx extract orally till post-natal day 14. The rats in each group were weaned and divided into two subgroups; one continued on normal rat chow, and the other received fructose (20% w/v) in their drinking water for 30 days. Blood was collected in heparinised tubes and added to serially diluted (0.0-0.85%) phosphate-buffered saline to determine the EOF. Clinical markers of health status were determined with an automated chemical analyser. HS extracts did not programme metabolism in the growing rats to alter their general health and EOF in response to the HFD. © 2017 Blackwell Verlag GmbH.

Assessment of chlorophyll variability along the northwestern coast of Iberian Peninsula

NASA Astrophysics Data System (ADS)

Picado, A.; Alvarez, I.; Vaz, N.; Varela, R.; Gomez-Gesteira, M.; Dias, J. M.

2014-10-01

The northwestern coast of the Iberian Peninsula is characterized by a high primary production mainly supported by coastal upwelling, creating an extraordinary commercial interest for fisheries and aquaculture. Considering chlorophyll-a (Chl-a) as an indicator of primary production, its spatio-temporal variability was researched in this study in the surface water of this upwelling region from 1998 to 2007. Satellite derived Chl-a, Sea Surface Temperature (SST) and Ekman transport data as well as the inflow of the main rivers discharging into the study area were used to investigate the origin of the Chl-a concentration. Empirical Orthogonal Function (EOF) analysis of weekly Chl-a images was performed, as well as correlation analysis between Chl-a concentration, Ekman transport and river discharge. EOF results suggest that the highest Chl-a concentration occurs near the coast up to 60 km offshore. The interannual variability of Chl-a, SST and Ekman transport was also studied considering summer and winter months. Generally, 2005, 2006 and 2007 were the most productive years during the summer months with high Chl-a concentrations along the coast associated to the strong upwelling conditions observed. Otherwise, 1998 seemed to be the most productive year during winter. The absence of upwelling favorable conditions together with localized low SST and considerable discharges, suggests that the high Chl-a concentrations observed during this period are mainly due to the entrance of nutrients through river runoff. However, in winter, high concentrations of colored dissolved organic matter (CDOM), associated with river runoff, are present in the ocean surface, leading to an erroneous strong signal of the satellite. During winter correlations of 0.58 and 0.49 were found between Chl-a concentration and Douro and Minho discharges, respectively, evidencing that high Chl-a concentration was related with river runoff. Otherwise, during summer, Chl-a and Ekman transport exhibited a correlation of - 0.38 indicating that high Chl-a is associated to upwelling events. In summary, it was found that the spatio-temporal variability of Chl-a along the northwestern coast of Iberian Peninsula exhibited the clear influence of upwelling events during summer. Conversely, the variability during winter was mainly due to entrance of nutrients through the rivers discharge which flow into the area.

ENSO-related Interannual Variability of Southern Hemisphere Atmospheric Circulation: Assessment and Projected Changes in CMIP5 Models

NASA Astrophysics Data System (ADS)

Frederiksen, Carsten; Grainger, Simon; Zheng, Xiaogu; Sisson, Janice

2013-04-01

ENSO variability is an important driver of the Southern Hemisphere (SH) atmospheric circulation. Understanding the observed and projected changes in ENSO variability is therefore important to understanding changes in Australian surface climate. Using a recently developed methodology (Zheng et al., 2009), the coherent patterns, or modes, of ENSO-related variability in the SH atmospheric circulation can be separated from modes that are related to intraseasonal variability or to changes in radiative forcings. Under this methodology, the seasonal mean SH 500 hPa geopotential height is considered to consist of three components. These are: (1) an intraseasonal component related to internal dynamics on intraseasonal time scales; (2) a slow-internal component related to internal dynamics on slowly varying (interannual or longer) time scales, including ENSO; and (3) a slow-external component related to external (i.e. radiative) forcings. Empirical Orthogonal Functions (EOFs) are used to represent the modes of variability of the interannual covariance of the three components. An assessment is first made of the modes in models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) dataset for the SH summer and winter seasons in the 20th century. In reanalysis data, two EOFs of the slow component (which includes the slow-internal and slow-external components) have been found to be related to ENSO variability (Frederiksen and Zheng, 2007). In SH summer, the CMIP5 models reproduce the leading ENSO mode very well when the structures of the EOF and the associated SST, and associated variance are considered. There is substantial improvement in this mode when compared with the CMIP3 models shown in Grainger et al. (2012). However, the second ENSO mode in SH summer has a poorly reproduced EOF structure in the CMIP5 models, and the associated variance is generally underestimated. In SH winter, the performance of the CMIP5 models in reproducing the structure and variance is similar for both ENSO modes, with the associated variance being generally underestimated. Projected changes in the modes in the 21st century are then investigated using ensembles of CMIP5 models that reproduce well the 20th century slow modes. The slow-internal and slow-external components are examined separately, allowing the projected changes in the response to ENSO variability to be separated from the response to changes in greenhouse gas concentrations. By using several ensembles, the model-dependency of the projected changes in the ENSO-related slow-internal modes is examined. Frederiksen, C. S., and X. Zheng, 2007: Variability of seasonal-mean fields arising from intraseasonal variability. Part 3: Application to SH winter and summer circulations. Climate Dyn., 28, 849-866. Grainger, S., C. S. Frederiksen, and X. Zheng, 2012: Modes of interannual variability of Southern Hemisphere atmospheric circulation in CMIP3 models: Assessment and Projections. Climate Dyn., in press. Zheng, X., D. M. Straus, C. S. Frederiksen, and S. Grainger, 2009: Potentially predictable patterns of extratropical tropospheric circulation in an ensemble of climate simulations with the COLA AGCM. Quart. J. Roy. Meteor. Soc., 135, 1816-1829.

Research highlights: June 1990 - May 1991

NASA Technical Reports Server (NTRS)

1991-01-01

Linear instability calculations at MSFC have suggested that the Geophysical Fluid Flow Cell (GFFC) should exhibit classic baroclinic instability at accessible parameter settings. Interest was in the mechanisms of transition to temporal chaos and the evolution of spatio-temporal chaos. In order to understand more about such transitions, high resolution numerical experiments for the physically simplest model of two layer baroclinic instability were conducted. This model has the advantage that the numerical code is exponentially convergent and can be efficiently run for very long times, enabling the study of chaotic attractors without the often devastating effects of low-order trunction found in many previous studies. Numerical algorithms for implementing an empirical orthogonal function (EOF) analysis of the high resolution numerical results were completed. Under conditions of rapid rotation and relatively low differential heating, convection in a spherical shell takes place as columnar banana cells wrapped around the annular gap, but with axes oriented along the axis of rotation; these were clearly evident in the GFFC experiments. The results of recent numerical simulations of columnar convection and future research plans are presented.

Reconstruction of regional mean temperature for East Asia since 1900s and its uncertainties

NASA Astrophysics Data System (ADS)

Hua, W.

2017-12-01

Regional average surface air temperature (SAT) is one of the key variables often used to investigate climate change. Unfortunately, because of the limited observations over East Asia, there were also some gaps in the observation data sampling for regional mean SAT analysis, which was important to estimate past climate change. In this study, the regional average temperature of East Asia since 1900s is calculated by the Empirical Orthogonal Function (EOF)-based optimal interpolation (OA) method with considering the data errors. The results show that our estimate is more precise and robust than the results from simple average, which provides a better way for past climate reconstruction. In addition to the reconstructed regional average SAT anomaly time series, we also estimated uncertainties of reconstruction. The root mean square error (RMSE) results show that the the error decreases with respect to time, and are not sufficiently large to alter the conclusions on the persist warming in East Asia during twenty-first century. Moreover, the test of influence of data error on reconstruction clearly shows the sensitivity of reconstruction to the size of the data error.

Analysis of the nonlinearity of Asian summer monsoon intraseasonal variability using spherical PDFs

NASA Astrophysics Data System (ADS)

Jajcay, Nikola; Hannachi, Abdel

2013-04-01

The Asian summer monsoon (ASM) is a high-dimensional and highly complex phenomenon affecting more than one fifth of the world population. The intraseasonal component of the ASM undergoes periods of active and break phases associated respectively with enhanced and reduced rainfall over the Indian subcontinent and surroundings. In this paper the nonlinear nature of the intraseasonal monsoon variability is investigated using the leading EOFs of ERA-40 sea level pressure reanalyses field over the ASM region. The probability density function is then computed in spherical coordinates using a Epaneshnikov kernel method. Three significant modes are identified. They represent respectively (i) East - West mode with above normal sea level pressure over East China sea and below normal pressure over Himalayas, (ii) mode with above normal sea level pressure over East China sea (without compensating centre of opposite sign as in (i)) and (iii) mode with below normal sea level pressure over East China sea (same as (ii) but with opposite sign). Relationship to large scale flow are also investigated and discussed.

10Be in late deglacial climate simulated by ECHAM5-HAM - Part 2: Isolating the solar signal from 10Be deposition

NASA Astrophysics Data System (ADS)

Heikkilä, U.; Shi, X.; Phipps, S. J.; Smith, A. M.

2014-04-01

This study investigates the effect of deglacial climate on the deposition of the solar proxy 10Be globally, and at two specific locations, the GRIP site at Summit, Central Greenland, and the Law Dome site in coastal Antarctica. The deglacial climate is represented by three 30 year time slice simulations of 10 000 BP (years before present = 1950 CE), 11 000 and 12 000 BP, compared with a preindustrial control simulation. The model used is the ECHAM5-HAM atmospheric aerosol-climate model, driven with sea-surface temperatures and sea ice cover simulated using the CSIRO Mk3L coupled climate system model. The focus is on isolating the 10Be production signal, driven by solar variability, from the weather- or climate-driven noise in the 10Be deposition flux during different stages of climate. The production signal varies at lower frequencies, dominated by the 11 year solar cycle within the 30 year timescale of these experiments. The climatic noise is of higher frequencies than 11 years during the 30 year period studied. We first apply empirical orthogonal function (EOF) analysis to global 10Be deposition on the annual scale and find that the first principal component, consisting of the spatial pattern of mean 10Be deposition and the temporally varying solar signal, explains 64% of the variability. The following principal components are closely related to those of precipitation. Then, we apply ensemble empirical decomposition (EEMD) analysis to the time series of 10Be deposition at GRIP and at Law Dome, which is an effective method for adaptively decomposing the time series into different frequency components. The low-frequency components and the long-term trend represent production and have reduced noise compared to the entire frequency spectrum of the deposition. The high-frequency components represent climate-driven noise related to the seasonal cycle of e.g. precipitation and are closely connected to high frequencies of precipitation. These results firstly show that the 10Be atmospheric production signal is preserved in the deposition flux to surface even during climates very different from today's both in global data and at two specific locations. Secondly, noise can be effectively reduced from 10Be deposition data by simply applying the EOF analysis in the case of a reasonably large number of available data sets, or by decomposing the individual data sets to filter out high-frequency fluctuations.

Speciation of mercury by hydrostatically modified electroosmotic flow capillary electrophoresis coupled with volatile species generation atomic fluorescence spectrometry.

PubMed

Yan, Xiu-Ping; Yin, Xue-Bo; Jiang, Dong-Qing; He, Xi-Wen

2003-04-01

A novel method for speciation analysis of mercury was developed by on-line hyphenating capillary electrophoresis (CE) with atomic fluorescence spectrometry (AFS). The four mercury species of inorganic mercury Hg(II), methymercury MeHg(I), ethylmercury EtHg(I), and phenylmercury PhHg(I) were separated as mercury-cysteine complexes by CE in a 50-cm x 100-microm-i.d. fused-silica capillary at 15 kV and using a mixture of 100 mmol L(-1) of boric acid and 12% v/v methanol (pH 9.1) as electrolyte. A novel technique, hydrostatically modified electroosmotic flow (HSMEOF) in which the electroosmotic flow (EOF) was modified by applying hydrostatical pressure opposite to the direction of EOF was used to improve resolution. A volatile species generation technique was used to convert the mercury species into their respective volatile species. A newly developed CE-AFS interface was employed to provide an electrical connection for stable electrophoretic separations and to allow on-line volatile species formation. The generated volatile species were on-line detected with AFS. The precisions (RSD, n = 5) were in the range of 1.9-2.5% for migration time, 1.8-6.3% for peak area response, and 2.3-6.1% for peak height response for the four mercury species. The detection limits ranged from 6.8 to 16.5 microg L(-1) (as Hg). The recoveries of the four mercury species in the water samples were in the range of 86.6-111%. The developed technique was successfully applied to speciation analysis of mercury in a certified reference material (DORM-2, dogfish muscle).

Annual asymmetry in thermospheric density: Observations and simulations

NASA Astrophysics Data System (ADS)

Lei, Jiuhou; Dou, Xiankang; Burns, Alan; Wang, Wenbin; Luan, Xiaoli; Zeng, Zhen; Xu, Jiyao

2013-05-01

In this paper, the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) observations during 2002-2010 are utilized to study the variation of the annual asymmetry in thermospheric density at 400 km under low solar activity condition (F10.7 = 80) based on the method of empirical orthogonal functions (EOFs). The derived asymmetry index (AI) in thermospheric density from the EOF analysis shows a strong latitudinal variation at night but varies a little with latitudes in daytime. Moreover, it exhibits a terdiurnal tidal signature at low to middle latitudes. The global mean value of the AI is 0.191, indicating that a 47% difference in thermosphere between the December and June solstices in the global average. In addition, the NCAR Thermosphere-Ionosphere Electrodynamics Global Circulation Model (TIEGCM) is used to explore the possible mechanisms responsible for the observed annual asymmetry in thermospheric density. It is found that the standard simulations give a lower AI and also a weaker day-to-night difference. The simulated AI shows a semidiurnal pattern in the equatorial and low-latitude regions in contrast with the terdiurnal tide signature seen in the observed AI. The daily mean AI obtained from the simulation is 0.125, corresponding to a 29% December-to-June difference in thermospheric density at 400 km. Further sensitivity simulations demonstrated that the effect of the varying Sun-Earth distance between the December and June solstices is the main process responsible for the annual asymmetry in thermospheric density, while the magnetic field configuration and tides from the lower atmosphere contribute to the temporal and spatial variations of the AI. Specifically, the simulations show that the Sun-Earth distance effect explains 93% of the difference in thermospheric density between December and June, which is mainly associated with the corresponding changes in neutral temperature. However, our calculation from the density observations reveals that the varying Sun-Earth distance effect only accounts for ~67% of the December-to-June difference in thermosphere density, indicating that the TIEGCM might significantly underestimate the forcing originating from the lower atmosphere.

Predictability of a Coupled Model of ENSO Using Singular Vector Analysis: Optimal Growth and Forecast Skill.

NASA Astrophysics Data System (ADS)

Xue, Yan

The optimal growth and its relationship with the forecast skill of the Zebiak and Cane model are studied using a simple statistical model best fit to the original nonlinear model and local linear tangent models about idealized climatic states (the mean background and ENSO cycles in a long model run), and the actual forecast states, including two sets of runs using two different initialization procedures. The seasonally varying Markov model best fit to a suite of 3-year forecasts in a reduced EOF space (18 EOFs) fits the original nonlinear model reasonably well and has comparable or better forecast skill. The initial error growth in a linear evolution operator A is governed by the eigenvalues of A^{T}A, and the square roots of eigenvalues and eigenvectors of A^{T}A are named singular values and singular vectors. One dominant growing singular vector is found, and the optimal 6 month growth rate is largest for a (boreal) spring start and smallest for a fall start. Most of the variation in the optimal growth rate of the two forecasts is seasonal, attributable to the seasonal variations in the mean background, except that in the cold events it is substantially suppressed. It is found that the mean background (zero anomaly) is the most unstable state, and the "forecast IC states" are more unstable than the "coupled model states". One dominant growing singular vector is found, characterized by north-south and east -west dipoles, convergent winds on the equator in the eastern Pacific and a deepened thermocline in the whole equatorial belt. This singular vector is insensitive to initial time and optimization time, but its final pattern is a strong function of initial states. The ENSO system is inherently unpredictable for the dominant singular vector can amplify 5-fold to 24-fold in 6 months and evolve into the large scales characteristic of ENSO. However, the inherent ENSO predictability is only a secondary factor, while the mismatches between the model and data is a primary factor controlling the current forecast skill.

North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model

NASA Technical Reports Server (NTRS)

Achuthavarier, Deepthi; Schubert, Siegfried D.; Vikhliaev, Yury V.

2013-01-01

This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the GEOS-5 general circulation model. The model simulates a realistic PDO pattern that is resolved as the first empirical orthogonal function (EOF) of winter sea surface temperature (SST). The simulated PDO is primarily forced by Aleutian low through Ekman transport and surface fluxes, and shows a red spectrum without any preferred periodicity. This differs from the observations, which indicate a greater role of El Nino-Southern Oscillation (ENSO) forcing, and likely reflects the too short time scale of the simulated ENSO. The geostrophic transport in response to the Aleutian low is limited to the Kuroshio-Oyashio Extension, and is unlikely the main controlling factor in this model, although it reinforces the Ekman-induced SST anomalies. The delay between the Aleutian low and the PDO is relatively short (1 year) suggesting that the fast Ekman response (rather than Rossby wave propagation) sets the SST pattern immediately following an Aleutian low fluctuation. The atmospheric feedback (response to the SST) is only about 25 of the forcing and never evolves into an Aleutian low completely, instead projecting onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure (SLP). The lack of preferred periodicity and weak atmospheric response bothindicate a coupled oscillation is an unlikely mechanism for the PDO in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation (NPGO), which is another leading EOF of the North Pacific SST. A possible connection between the PDO and the NPGO is discussed.

North Pacific decadal variability: insights from a biennial ENSO environment

NASA Astrophysics Data System (ADS)

Achuthavarier, Deepthi; Schubert, Siegfried D.; Vikhliaev, Yury V.

2017-08-01

This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the NASA GEOS-5 general circulation model (GCM). Similar to several other state-of-the-art GCMs, the El Niño-Southern Oscillation (ENSO) simulated by the GEOS-5 has a strong biennial periodicity. Since this is a model bias that precludes a strong role of ENSO, it provides a unique environment to assess the other leading mechanisms of North Pacific decadal variability. Despite the biennial ENSO periodicity, the model simulates a realistic PDO pattern in the North Pacific that is resolved as the first empirical orthogonal function (EOF) of winter mean sea surface temperature (SST). The spectrum of the PDO indicates no preferred periodicity. The SST anomalies associated with the PDO, particularly its basin wide structure, are primarily forced by the Aleutian low through Ekman transport. The slow geostrophic transport in association with the meridional adjustment of the subtropical gyre is limited to a narrow region in the Kuroshio-Oyashio extension, north of 40°N. The atmosphere's response to the PDO, while weak, projects onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure. Both the lack of preferred periodicity and the weak atmospheric response indicate an air-sea coupled oscillation is an unlikely mechanism in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation, which is another leading EOF of North Pacific SST variability. The results emphasize the role of atmospheric variability in the North Pacific SST modes, thereby bringing into question the potential for their predictability.

North Pacific Decadal Variability: Insights from a Biennial ENSO Environment

NASA Technical Reports Server (NTRS)

Achuthavarier, Deepthi; Schubert, Siegfried D.; Vikhliaev, Yury V.

2016-01-01

This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the NASA GEOS-5 general circulation model (GCM). Similar to several other state-of-the-art GCMs, the El Niño-Southern Oscillation (ENSO) simulated by the GEOS-5 has a strong biennial periodicity. Since this is a model bias that precludes a strong role of ENSO, it provides a unique environment to assess the other leading mechanisms of North Pacific decadal variability. Despite the biennial ENSO periodicity, the model simulates a realistic PDO pattern in the North Pacific that is resolved as the first empirical orthogonal function (EOF) of winter mean sea surface temperature (SST). The spectrum of the PDO indicates no preferred periodicity. The SST anomalies associated with the PDO, particularly its basin wide structure, are primarily forced by the Aleutian low through Ekman transport. The slow geostrophic transport in association with the meridional adjustment of the subtropical gyre is limited to a narrow region in the Kuroshio-Oyashio extension, north of 40degN. The atmosphere's response to the PDO, while weak, projects onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure. Both the lack of preferred periodicity and the weak atmospheric response indicate an air-sea coupled oscillation is an unlikely mechanism in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation, which is another leading EOF of North Pacific SST variability. The results emphasize the role of atmospheric variability in the North Pacific SST modes, thereby bringing into question the potential for their predictability.

Multiset canonical correlations analysis and multispectral, truly multitemporal remote sensing data.

PubMed

Nielsen, Allan Aasbjerg

2002-01-01

This paper describes two- and multiset canonical correlations analysis (CCA) for data fusion, multisource, multiset, or multitemporal exploratory data analysis. These techniques transform multivariate multiset data into new orthogonal variables called canonical variates (CVs) which, when applied in remote sensing, exhibit ever-decreasing similarity (as expressed by correlation measures) over sets consisting of 1) spectral variables at fixed points in time (R-mode analysis), or 2) temporal variables with fixed wavelengths (T-mode analysis). The CVs are invariant to linear and affine transformations of the original variables within sets which means, for example, that the R-mode CVs are insensitive to changes over time in offset and gain in a measuring device. In a case study, CVs are calculated from Landsat Thematic Mapper (TM) data with six spectral bands over six consecutive years. Both Rand T-mode CVs clearly exhibit the desired characteristic: they show maximum similarity for the low-order canonical variates and minimum similarity for the high-order canonical variates. These characteristics are seen both visually and in objective measures. The results from the multiset CCA R- and T-mode analyses are very different. This difference is ascribed to the noise structure in the data. The CCA methods are related to partial least squares (PLS) methods. This paper very briefly describes multiset CCA-based multiset PLS. Also, the CCA methods can be applied as multivariate extensions to empirical orthogonal functions (EOF) techniques. Multiset CCA is well-suited for inclusion in geographical information systems (GIS).

On the estimation of physical height changes using GRACE satellite mission data - A case study of Central Europe

NASA Astrophysics Data System (ADS)

Godah, Walyeldeen; Szelachowska, Małgorzata; Krynski, Jan

2017-12-01

The dedicated gravity satellite missions, in particular the GRACE (Gravity Recovery and Climate Experiment) mission launched in 2002, provide unique data for studying temporal variations of mass distribution in the Earth's system, and thereby, the geometry and the gravity fi eld changes of the Earth. The main objective of this contribution is to estimate physical height (e.g. the orthometric/normal height) changes over Central Europe using GRACE satellite mission data as well as to analyse them and model over the selected study area. Physical height changes were estimated from temporal variations of height anomalies and vertical displacements of the Earth surface being determined over the investigated area. The release 5 (RL05) GRACE-based global geopotential models as well as load Love numbers from the Preliminary Reference Earth Model (PREM) were used as input data. Analysis of the estimated physical height changes and their modelling were performed using two methods: the seasonal decomposition method and the PCA/ EOF (Principal Component Analysis/Empirical Orthogonal Function) method and the differences obtained were discussed. The main fi ndings reveal that physical height changes over the selected study area reach up to 22.8 mm. The obtained physical height changes can be modelled with an accuracy of 1.4 mm using the seasonal decomposition method.

Impacts of Climate Variability on the Spatio-temporal Characteristics of Water Stress in Korea

NASA Astrophysics Data System (ADS)

Kim, Soojun; Devineni, Naresh; Lall, Upmanu; Kim, Hung Soo

2017-04-01

This study intended to evaluate water stress quantitatively targeted at the Korean Peninsula and to analyze the spatial and temporal characteristics of its occurrence. First, the severity and multiyear influence of water stress were analyzed by realizing water balance based on water supply and demand and by calculating the normalized deficit index (NDI) and the normalized deficit cumulated (NDC) for 113 small basins in the Korean Peninsula. Next, a change in the periodic characteristics of water stress was analyzed using wavelet transform of the NDI by small basins and 3 bands of periods of 1 year, 2-4 years, and 4-8 years were separated. Through an analysis of the empirical orthogonal function (EOF) on each band, it was found that water stress occurring in the Korean Peninsula has the characteristics of spatial distribution that it is extended from the south coast to the northern area and inland as its period gets longer. An analysis of the band with a period of 2-8 years for water stress showed that it has a relationship with El Niño-Southern Oscillation (ENSO). Acknowledgment This research was supported by a grant (14AWMP-B082564-01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

An Innovative Metric to Evaluate Satellite Precipitation's Spatial Distribution

NASA Astrophysics Data System (ADS)

Liu, H.; Chu, W.; Gao, X.; Sorooshian, S.

2011-12-01

Thanks to its capability to cover the mountains, where ground measurement instruments cannot reach, satellites provide a good means of estimating precipitation over mountainous regions. In regions with complex terrains, accurate information on high-resolution spatial distribution of precipitation is critical for many important issues, such as flood/landslide warning, reservoir operation, water system planning, etc. Therefore, in order to be useful in many practical applications, satellite precipitation products should possess high quality in characterizing spatial distribution. However, most existing validation metrics, which are based on point/grid comparison using simple statistics, cannot effectively measure satellite's skill of capturing the spatial patterns of precipitation fields. This deficiency results from the fact that point/grid-wised comparison does not take into account of the spatial coherence of precipitation fields. Furth more, another weakness of many metrics is that they can barely provide information on why satellite products perform well or poor. Motivated by our recent findings of the consistent spatial patterns of the precipitation field over the western U.S., we developed a new metric utilizing EOF analysis and Shannon entropy. The metric can be derived through two steps: 1) capture the dominant spatial patterns of precipitation fields from both satellite products and reference data through EOF analysis, and 2) compute the similarities between the corresponding dominant patterns using mutual information measurement defined with Shannon entropy. Instead of individual point/grid, the new metric treat the entire precipitation field simultaneously, naturally taking advantage of spatial dependence. Since the dominant spatial patterns are shaped by physical processes, the new metric can shed light on why satellite product can or cannot capture the spatial patterns. For demonstration, a experiment was carried out to evaluate a satellite precipitation product, CMORPH, against the U.S. daily precipitation analysis of Climate Prediction Center (CPC) at a daily and .25o scale over the Western U.S.

The Deepwater Horizon oil spill and Gulf of Mexico shelf hypoxia

NASA Astrophysics Data System (ADS)

Rabalais, Nancy N.; Smith, Leslie M.; Turner, R. Eugene

2018-01-01

The oil/water/dispersant mixture from the 2010 Deepwater Horizon oil spill was juxtaposed on the Louisiana continental shelf with the annual development of oxygen-depleted bottom waters. There was uncertainty whether the oil from the spill might worsen the extent or severity of the seasonal hypoxic area formation in 2010. The surface and bottom water hydrocarbons in May were elevated compared to in June and July, while the bottom-water dissolved oxygen concentrations were higher in May and June compared to in July. The degradation of oil in the water column or sediments was not known. The results of an empirical orthogonal functions (EOF) analysis of the progression of hypoxia development in May, June and July 2010, and an analysis of conditions in July compared to a 27-year background database, indicated no difference in oxygen concentrations for May, June or July 2010, with or without oil data included, nor any difference in July 2010 compared to other years. The analysis instead indicated that, in all years compared, the hypoxic area increased with higher river discharge, higher nitrate-N load, an easterly (westward) wind and reduced wind speed. Although the analyses did not demonstrate that the oil spill affected, or did not affect, the size of the 2010 hypoxic zone, there was evidence that the 2010 hypoxia season did not differ from the long-term record.

Inference of Global Mean Temperature Trend and Climate Change from MSU and AMSU

NASA Technical Reports Server (NTRS)

Prabhakara, Cuddapah; Iacovazzi, R. A., Jr.; Yoo, J.-M.; Lau, William K. M. (Technical Monitor)

2001-01-01

Microwave Sounding Unit (MSU) and Advanced MSU (AMSU) radiometers flown on the NOAA operational satellite series are potentially valuable as global temperature monitoring devices. Spencer and Christy pioneered the analysis of mid-tropospheric temperature, given by MSU Channel 2 (Ch 2) at 53.74 GHz, to derive the global temperature trend. Also, in addition to monitoring global temperature, these microwave radiometers have the potential to reveal interannual climate signals in tropics. We have analyzed the data of MSU Ch 2 and AMSU Ch 5 (53.6 GHz) from the NOAA operational satellites for the period 1980 to 2000, utilizing the NOAA calibration procedure. The data are corrected for the satellite orbital drift based on the temporal changes of the on-board warm blackbody temperature. From our analysis, we find that the global temperature increased at a rate of 0.13 +/- 0.05 Kdecade(sup -1) during 1980 to 2000. From an Empirical Orthogonal Function (EOF) analysis of the MSU global data, we find that the mid-tropospheric temperature in middle and high latitudes responds to the ENSO forcing during the Northern Hemisphere Winter in a distinct manner. This mid-latitude response is opposite in phase to that in the tropics. This result is in accord with simulations performed with an ECMWF global spectral model. This study shows a potential use of the satellite observations for climatic change.

Developing a Complex Independent Component Analysis (CICA) Technique to Extract Non-stationary Patterns from Geophysical Time Series

NASA Astrophysics Data System (ADS)

Forootan, Ehsan; Kusche, Jürgen; Talpe, Matthieu; Shum, C. K.; Schmidt, Michael

2017-12-01

In recent decades, decomposition techniques have enabled increasingly more applications for dimension reduction, as well as extraction of additional information from geophysical time series. Traditionally, the principal component analysis (PCA)/empirical orthogonal function (EOF) method and more recently the independent component analysis (ICA) have been applied to extract, statistical orthogonal (uncorrelated), and independent modes that represent the maximum variance of time series, respectively. PCA and ICA can be classified as stationary signal decomposition techniques since they are based on decomposing the autocovariance matrix and diagonalizing higher (than two) order statistical tensors from centered time series, respectively. However, the stationarity assumption in these techniques is not justified for many geophysical and climate variables even after removing cyclic components, e.g., the commonly removed dominant seasonal cycles. In this paper, we present a novel decomposition method, the complex independent component analysis (CICA), which can be applied to extract non-stationary (changing in space and time) patterns from geophysical time series. Here, CICA is derived as an extension of real-valued ICA, where (a) we first define a new complex dataset that contains the observed time series in its real part, and their Hilbert transformed series as its imaginary part, (b) an ICA algorithm based on diagonalization of fourth-order cumulants is then applied to decompose the new complex dataset in (a), and finally, (c) the dominant independent complex modes are extracted and used to represent the dominant space and time amplitudes and associated phase propagation patterns. The performance of CICA is examined by analyzing synthetic data constructed from multiple physically meaningful modes in a simulation framework, with known truth. Next, global terrestrial water storage (TWS) data from the Gravity Recovery And Climate Experiment (GRACE) gravimetry mission (2003-2016), and satellite radiometric sea surface temperature (SST) data (1982-2016) over the Atlantic and Pacific Oceans are used with the aim of demonstrating signal separations of the North Atlantic Oscillation (NAO) from the Atlantic Multi-decadal Oscillation (AMO), and the El Niño Southern Oscillation (ENSO) from the Pacific Decadal Oscillation (PDO). CICA results indicate that ENSO-related patterns can be extracted from the Gravity Recovery And Climate Experiment Terrestrial Water Storage (GRACE TWS) with an accuracy of 0.5-1 cm in terms of equivalent water height (EWH). The magnitude of errors in extracting NAO or AMO from SST data using the complex EOF (CEOF) approach reaches up to 50% of the signal itself, while it is reduced to 16% when applying CICA. Larger errors with magnitudes of 100% and 30% of the signal itself are found while separating ENSO from PDO using CEOF and CICA, respectively. We thus conclude that the CICA is more effective than CEOF in separating non-stationary patterns.

Using synchronization in multi-model ensembles to improve prediction

NASA Astrophysics Data System (ADS)

Hiemstra, P.; Selten, F.

2012-04-01

In recent decades, many climate models have been developed to understand and predict the behavior of the Earth's climate system. Although these models are all based on the same basic physical principles, they still show different behavior. This is for example caused by the choice of how to parametrize sub-grid scale processes. One method to combine these imperfect models, is to run a multi-model ensemble. The models are given identical initial conditions and are integrated forward in time. A multi-model estimate can for example be a weighted mean of the ensemble members. We propose to go a step further, and try to obtain synchronization between the imperfect models by connecting the multi-model ensemble, and exchanging information. The combined multi-model ensemble is also known as a supermodel. The supermodel has learned from observations how to optimally exchange information between the ensemble members. In this study we focused on the density and formulation of the onnections within the supermodel. The main question was whether we could obtain syn-chronization between two climate models when connecting only a subset of their state spaces. Limiting the connected subspace has two advantages: 1) it limits the transfer of data (bytes) between the ensemble, which can be a limiting factor in large scale climate models, and 2) learning the optimal connection strategy from observations is easier. To answer the research question, we connected two identical quasi-geostrohic (QG) atmospheric models to each other, where the model have different initial conditions. The QG model is a qualitatively realistic simulation of the winter flow on the Northern hemisphere, has three layers and uses a spectral imple-mentation. We connected the models in the original spherical harmonical state space, and in linear combinations of these spherical harmonics, i.e. Empirical Orthogonal Functions (EOFs). We show that when connecting through spherical harmonics, we only need to connect 28% of the state variables to obtain synchronization. In addition, when connecting through EOFs, we can reduce this percentage even more to 12%. This reduction is caused by the more efficient description of the model state variables when using EOFs. The connected state variables center around the medium scale structures in the model. Small and large scale structures need not be connected in order to obtain synchronization. This could be related to the baroclinic instabilities in the QG model which are located in the medium scale structures of the model. The baroclinic instabilities are the main source of divergence between the two connected models.

Effects of L-glutamine on rectal temperature and some markers of oxidative stress in Red Sokoto goats during the hot-dry season.

PubMed

Ocheja, Ohiemi Benjamin; Ayo, Joseph Olusegun; Aluwong, Tagang; Minka, Ndazo Salka

2017-08-01

The experiment investigated the ameliorative effects of L-glutamine administration on rectal temperature (RT), erythrocyte osmotic fragility (EOF), serum antioxidant enzyme activities and malondialdehyde (MDA) concentration in Red Sokoto goats during the hot-dry season. Twenty eight healthy Red Sokoto goats, comprising 14 experimental (administered 0.2 g/kg of L-glutamine dissolved in 10 mL of distilled water, once daily for 21 days) and 14 control (administered equivalent of distilled water) goats served as subjects. Rectal temperature (measured at 6:00, 13:00 and 18:00 h) and blood samples (taken at 8:00 h) were obtained from all subjects weekly, before, during and after L-glutamine administration. Data obtained were compared using one-way repeated-measures ANOVA, followed by Tukey's post-hoc test. The dry-bulb temperature, relative humidity and temperature-humidity index for the study period ranged between 24.0 and 37.5 °C, 26.0 and 84.0% and 73.0 and 86.3, respectively. L-glutamine administration decreased (P < 0.05) RT, EOF and MDA and increased superoxide dismutase (SOD) activity in experimental group, compared to controls during weeks 1, 2 and 3. Glutathione peroxidase (GPx) and catalase activities were higher (P < 0.05) in the experimental group than in the controls only during week 1 of L-glutamine administration. In conclusion, L-glutamine administration mitigated increases in RT, EOF and serum MDA concentration and enhanced serum SOD, GPx and catalase activities and may be beneficial in heat-stressed goats during the hot-dry season.

Cryohemolysis, erythrocyte osmotic fragility, and supplementary hematimetric indices in the diagnosis of hereditary spherocytosis.

PubMed

Emilse, Ledesma Achem Miryam; Cecilia, Haro; María, Terán Magdalena; Eugenia, Mónaco María; Alicia, Issé Blanca; Lazarte, Sandra Stella

2018-03-01

Hereditary spherocytosis (HS) is a chronic hemolytic anemia characterized by microspherocytes in the peripheral blood and increased erythrocyte osmotic fragility (EOF). This study evaluated the cryohemolysis test (CHT); initial hemolysis (IH); immediate and incubated hemolysis percentage in 5.5 g/L NaCl (H5.5); mean corpuscular hemoglobin concentration (MCHC); red blood cell distribution width (RDW); and Hb/MCHC, Hb/RDW, and MCHC/RDW ratios for the diagnosis of HS. Data from 13 patients with HS were evaluated at the Instituto de Bioquímica Aplicada and compared with data from 14 unaffected individuals and 11 patients with anemia due to another etiology. Total blood and reticulocyte counts, CHT, and immediate and incubated EOF were performed in all subjects; sensitivity, specificity, efficiency, and Youden index (YI) were calculated. Eight patients with HS had MCHC ≥345 g/L, 10 had RDW ≥14.5%, 12 had IH >5.0 g/L, 11 had immediate H5.5 ≥5%, and 13 had incubated H5.5 ≥50% (the cut-off value to consider HS). The efficiency and YI were: immediate H5.5 (0.94-0.85), incubated H5.5 (0.89-0.82), IH (0.89-0.78), MCHC (0.87-0.62), CHT (0.84-0.54), and Hb/MCHC (0.71-0.56), respectively. The calculated ratios could distinguish subjects with HS from unaffected individuals ( P <0.05), but not those with anemia of another etiology ( P >0.05). Although the CHT and supplementary hematimetric indexes were useful to differentiate individuals with SH from healthy controls, they cannot distinguish from anemias of other etiology. CHT and MCHC, in addition to EOF, are recommended for diagnosing HS patients because of their low cost and efficiency.

Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

PubMed

Hayes, J D; Malik, A

2001-03-01

Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

Combination Base64 Algorithm and EOF Technique for Steganography

NASA Astrophysics Data System (ADS)

Rahim, Robbi; Nurdiyanto, Heri; Hidayat, Rahmat; Saleh Ahmar, Ansari; Siregar, Dodi; Putera Utama Siahaan, Andysah; Faisal, Ilham; Rahman, Sayuti; Suita, Diana; Zamsuri, Ahmad; Abdullah, Dahlan; Napitupulu, Darmawan; Ikhsan Setiawan, Muhammad; Sriadhi, S.

2018-04-01

The steganography process combines mathematics and computer science. Steganography consists of a set of methods and techniques to embed the data into another media so that the contents are unreadable to anyone who does not have the authority to read these data. The main objective of the use of base64 method is to convert any file in order to achieve privacy. This paper discusses a steganography and encoding method using base64, which is a set of encoding schemes that convert the same binary data to the form of a series of ASCII code. Also, the EoF technique is used to embed encoding text performed by Base64. As an example, for the mechanisms a file is used to represent the texts, and by using the two methods together will increase the security level for protecting the data, this research aims to secure many types of files in a particular media with a good security and not to damage the stored files and coverage media that used.

Wave spectral energy variability in the northeast Pacific

USGS Publications Warehouse

Bromirski, P.D.; Cayan, D.R.; Flick, R.E.

2005-01-01

The dominant characteristics of wave energy variability in the eastern North Pacific are described from NOAA National Data Buoy Center (NDBC) buoy data collected from 1981 to 2003. Ten buoys at distributed locations were selected for comparison based on record duration and data continuity. Long-period (LP) [T > 12] s, intermediate-period [6 ??? T ??? 12] s, and short-period [T < 6] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses of monthly wave energy anomalies reveal that all three wave energy components exhibit similar patterns of spatial variability. The dominant mode represents coherent heightened (or diminished) wave energy along the West Coast from Alaska to southern California, as indicated by composites of the 700 hPa height field. The second EOF mode reveals a distinct El Nin??o-Southern Oscillation (ENSO)-associated spatial distribution of wave energy, which occurs when the North Pacific storm track is extended unusually far south or has receded to the north. Monthly means and principal components (PCs) of wave energy levels indicate that the 1997-1998 El Nin??o winter had the highest basin-wide wave energy within this record, substantially higher than the 1982-1983 El Nin??o. An increasing trend in the dominant PC of LP wave energy suggests that storminess has increased in the northeast Pacific since 1980. This trend is emphasized at central eastern North Pacific locations. Patterns of storminess variability are consistent with increasing activity in the central North Pacific as well as the tendency for more extreme waves in the south during El Nin??o episodes and in the north during La Nin??a. Copyright 2005 by the American Geophysical Union.

European Climate and Pinot Noir Grape-Harvest Dates in Burgundy, since the 17th Century

NASA Astrophysics Data System (ADS)

Tourre, Y. M.

2011-12-01

Time-series of growing season air temperature anomalies in the Parisian region and of 'Pinot Noir' grape-harvest dates (GHD) in Burgundy (1676-2004) are analyzed in the frequency-domain. Variability of both time-series display three significant frequency-bands (peaks significant at the 5% level) i.e., a low-frequency band (multi-decadal) with a 25-year peak period; a 3-to-8 year band period (inter-annual) with a 3.1-year peak period; and a 2-to-3 year band period (quasi-biennial) with a 2.4-year peak period. Joint sea surface temperature/sea level pressure (SST/SLP) empirical orthogonal functions (EOF) analyses during the 20th century, along with spatio-temporal patterns for the above frequency-bands are presented. It is found that SST anomalies display early significant spatial SST patterns in the North Atlantic Ocean (air temperature lagging by 6 months) similar to those obtained from EOF analyses. It is thus proposed that the robust power spectra for the above frequency-bands could be linked with Atlantic climate variability metrics modulating Western European climate i.e., 1) the global Multi-decadal Oscillation (MDO) with its Atlantic Multi-decadal Oscillation (AMO) footprint; 2) the Atlantic Inter-Annual (IA) fluctuations; and 3) the Atlantic Quasi-Biennial (QB) fluctuations, respectively. Moreover these specific Western European climate signals have effects on ecosystem health and can be perceived as contributors to the length of the growing season and the timing of GHD in Burgundy. Thus advance knowledge on the evolution and phasing of the above climate fluctuations become important elements for viticulture and wine industry management. It is recognized that anthropogenic effects could have modified time-series patterns presented here, particularly since the mid 1980s.

Decadal-period external magnetic field variations resolved with eigenanalysis

NASA Astrophysics Data System (ADS)

Shore, Robert; Whaler, Kathryn; Macmillan, Susan; Beggan, Ciarán; Velímský, Jakub; Olsen, Nils

2017-04-01

Variations in the magnetic field at and above the Earth's surface permeate the interior of our planet, and can be used to determine the electrical conductivity of the mantle. Presently, the annual and semi-annual period fields induced by magnetospheric and ionospheric currents, suitable to estimate mantle conductivity in the approximate depth range 1,200-2,000 km, are subject to large uncertainty since they overlap with the periods on which the core field also changes significantly. It is timely to obtain an improved determination of the spatial geometry of the external, inducing, fields in order to better separate their internal, induced, part from that generated in the core. We apply the method of Empirical Orthogonal Functions (EOFs) to a dataset of ground-based magnetic observatory hourly means in order to decompose the external magnetic field during quiet times over a full 11-year solar cycle into its modes of maximum variance. This allows us to assess the spatial structures and magnitude changes of its dominant spatio-temporal patterns. Specifically, our focus is on isolating the long period external inducing fields as they penetrate to the depths of the mantle where the conductivity is least constrained. We expand ground-based measurements in the inertial local-time frame to produce spherical harmonic models of the dominant long period signals isolated by the EOF method. Whilst the ring current dominates the decomposition, we show that an annual and a semi-annual oscillation are important in describing the full inducing field. Each of these terms exhibits a modulation from the 11-year solar cycle. In summary, the most important harmonic in the description of the inducing fields is P10, followed by P21. There are lesser but still significant contributions from the P11 and P20 harmonics.

Predictable patterns of the May-June rainfall anomaly over East Asia

NASA Astrophysics Data System (ADS)

Xing, Wen; Wang, Bin; Yim, So-Young; Ha, Kyung-Ja

2017-02-01

During early summer (May-June, MJ), East Asia (EA) subtropical front is a defining feature of Asian monsoon, which produces the most prominent precipitation band in the global subtropics. Here we show that dynamical prediction of early summer EA (20°N-45°N, 100°E-130°E) rainfall made by four coupled climate models' ensemble hindcast (1979-2010) yields only a moderate skill and cannot be used to estimate predictability. The present study uses an alternative, empirical orthogonal function (EOF)-based physical-empirical (P-E) model approach to predict rainfall anomaly pattern and estimate its potential predictability. The first three leading modes are physically meaningful and can be, respectively, attributed to (a) the interaction between the anomalous western North Pacific subtropical high and underlying Indo-Pacific warm ocean, (b) the forcing associated with North Pacific sea surface temperature (SST) anomaly, and (c) the development of equatorial central Pacific SST anomalies. A suite of P-E models is established to forecast the first three leading principal components. All predictors are 0 month ahead of May, so the prediction here is named as a 0 month lead prediction. The cross-validated hindcast results demonstrate that these modes may be predicted with significant temporal correlation skills (0.48-0.72). Using the predicted principal components and the corresponding EOF patterns, the total MJ rainfall anomaly was hindcasted for the period of 1979-2015. The time-mean pattern correlation coefficient (PCC) score reaches 0.38, which is significantly higher than dynamical models' multimodel ensemble skill (0.21). The estimated potential maximum attainable PCC is around 0.65, suggesting that the dynamical prediction models may have large rooms to improve. Limitations and future work are discussed.

Interannual variability of western North Pacific SST anomalies and its impact on North Pacific and North America

NASA Astrophysics Data System (ADS)

Park, Jae-Heung; An, Soon-Il; Kug, Jong-Seong

2017-12-01

In this study, the interannual variability of sea surface temperature (SST) and its atmospheric teleconnection over the western North Pacific (WNP) toward the North Pacific/North America during boreal winter are investigated. First, we defined the WNP mode as the first empirical orthogonal function (EOF) mode of SST anomalies over the WNP region (100-165°E, 0-35°N), of which the principle component time-series are significantly correlated with several well-known climate modes such as the warm pool mode which is the second EOF mode of the tropical to North Pacific SST anomalies, North Pacific oscillation (NPO), North Pacific gyre oscillation (NPGO), and central Pacific (CP)-El Niño at 95% confidence level, but not correlated with the eastern Pacific (EP)-El Niño. The warm phase of the WNP mode (sea surface warming) is initiated by anomalous southerly winds through reduction of wind speed with the background of northerly mean winds over the WNP during boreal winter, i.e., reduced evaporative cooling. Meanwhile, the atmospheric response to the SST warming pattern and its diabatic heating further enhance the southerly wind anomaly, referred to the wind-evaporation-SST (WES) feedback. Thus, the WNP mode is developed and maintained through winter until spring, when the northerly mean wind disappears. Furthermore, it is also known that anomalous upper-level divergence associated with WNP mode leads to the NPO-like structure over the North Pacific and the east-west pressure contrast pattern over the North America through Rossby wave propagation, impacting the climate over the North Pacific and North America.

Comparison of field-enhanced and pressure-assisted field-enhanced sample injection techniques for the analysis of water-soluble vitamins using CZE.

PubMed

Liu, Qingqing; Liu, Yaling; Guan, Yu; Jia, Li

2009-04-01

A new online concentration method, namely pressure-assisted field-enhanced sample injection (PA-FESI), was developed and compared with FESI for the analysis of water-soluble vitamins by CZE with UV detection. In PA-FESI, negative voltage and positive pressure were simultaneously applied to initialize PA-FESI. PA-FESI uses the hydrodynamic flow generated by the positive pressure to counterbalance the reverse EOF in the capillary column during electrokinetic sample injection, which allowed a longer injection time than usual FESI mode without compromising the separation efficiency. Using the PA-FESI method, the LODs of the vitamins were at ng/mL level based on the S/N of 3 and the RSDs of migration time and peak area for each vitamin (1 microg/mL) were less than 5.1%. The developed method was applied to the analysis of water-soluble vitamins in corns.

Signals of El Niño Modoki in the tropical tropopause layer and stratosphere

NASA Astrophysics Data System (ADS)

Xie, F.; Li, J.; Tian, W.; Feng, J.; Huo, Y.

2012-06-01

The effects of El Niño Modoki events on the tropical tropopause layer (TTL) and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF) reanalysis data, oceanic El Niño indices, and general climate model outputs. El Niño Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during El Niño Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pacific upper troposphere. The spatial patterns of the outgoing longwave radiation (OLR) and upper tropospheric water vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF) analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Niño events are associated with the leading mode of the EOF, while El Niño Modoki events correspond to the second mode. The composite analysis based on ERA-interim data indicate that El Niño Modoki events have a reverse effect on middle-high latitudes stratosphere, as compared with the effect of typical El Niño events, i.e., the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Niño Modoki events. According to the simulation' results, we found that the reverse effect on the middle-high latitudes stratosphere is resulted from a complicated interaction between quasi-biennial oscillation (QBO) signal of east phase and El Niño Modoki signal. This interaction is not a simply linear overlay of QBO signal and El Niño Modoki signal in the stratosphere, it is El Niño Modoki that leads to different tropospheric zonal wind anomalies with QBO forcing from that caused by typical El Niño, thus, the planetary wave propagation from troposphere to the stratosphere during El Niño Modoki events is different from that during canonical El Niño events. However, when QBO is in its west phase, El Niño Modoki events have the same effect on middle-high latitudes stratosphere as the typical El Niño events. Our simulations also suggest that canonical El Niño and El Niño Modoki activities actually have the same influence on the middle-high latitudes stratosphere when in the absence of QBO forcing.

Dispersal of the Pearl River plume over continental shelf in summer

NASA Astrophysics Data System (ADS)

Chen, Zhaoyun; Gong, Wenping; Cai, Huayang; Chen, Yunzhen; Zhang, Heng

2017-07-01

Satellite images of turbidity were used to study the climatological, monthly, and typical snapshot distributions of the Pearl River plume over the shelf in summer from 2003 to 2016. These images show that the plume spreads offshore over the eastern shelf and is trapped near the coast over the western shelf. Eastward extension of the plume retreats from June to August. Monthly spatial variations of the plume are characterized by eastward spreading, westward spreading, or both. Time series of monthly plume area was quantified by applying the K-mean clustering method to identify the turbid plume water. Decomposition of the 14-year monthly turbidity data by the empirical orthogonal function (EOF) analysis isolated the 1st mode in both the eastward and westward spreading pattern as the time series closely related to the Pearl River discharge, and the 2nd mode with out-of-phase turbidity anomalies over the eastern and western shelves that is associated with the prevailing wind direction. Eight typical plume types were detected from the satellite snapshots. They are characterized by coastal jet, eastward offshore spreading, westward spreading, bidirectional spreading, bulge, isolated patch, offshore branch, and offshore filaments, respectively. Their possible mechanisms are discussed.

U.S. ports and the funding of intermodal facilities : an overview of key issues

DOT National Transportation Integrated Search

2000-03-28

The growing us eof containers to move freight has led carriers to use fewer but larger ports. In their efforts to attract and retain carriers, U.S. ports have made or are planning substantial investments in new berths, docks, and improved connections...

Exploring image data assimilation in the prospect of high-resolution satellite oceanic observations

NASA Astrophysics Data System (ADS)

Durán Moro, Marina; Brankart, Jean-Michel; Brasseur, Pierre; Verron, Jacques

2017-07-01

Satellite sensors increasingly provide high-resolution (HR) observations of the ocean. They supply observations of sea surface height (SSH) and of tracers of the dynamics such as sea surface salinity (SSS) and sea surface temperature (SST). In particular, the Surface Water Ocean Topography (SWOT) mission will provide measurements of the surface ocean topography at very high-resolution (HR) delivering unprecedented information on the meso-scale and submeso-scale dynamics. This study investigates the feasibility to use these measurements to reconstruct meso-scale features simulated by numerical models, in particular on the vertical dimension. A methodology to reconstruct three-dimensional (3D) multivariate meso-scale scenes is developed by using a HR numerical model of the Solomon Sea region. An inverse problem is defined in the framework of a twin experiment where synthetic observations are used. A true state is chosen among the 3D multivariate states which is considered as a reference state. In order to correct a first guess of this true state, a two-step analysis is carried out. A probability distribution of the first guess is defined and updated at each step of the analysis: (i) the first step applies the analysis scheme of a reduced-order Kalman filter to update the first guess probability distribution using SSH observation; (ii) the second step minimizes a cost function using observations of HR image structure and a new probability distribution is estimated. The analysis is extended to the vertical dimension using 3D multivariate empirical orthogonal functions (EOFs) and the probabilistic approach allows the update of the probability distribution through the two-step analysis. Experiments show that the proposed technique succeeds in correcting a multivariate state using meso-scale and submeso-scale information contained in HR SSH and image structure observations. It also demonstrates how the surface information can be used to reconstruct the ocean state below the surface.

A star-shaped poly(2-methyl-2-oxazoline)-based antifouling coating: Application in investigation of the interaction between acetaminophen and bovine serum albumin by frontal analysis capillary electrophoresis.

PubMed

Du, Haiqin; Zhang, Chong; Mao, Ke; Wang, Yanmei

2017-08-01

In this work, an antifouling capillary modified with star-shaped poly(2-methyl-2-oxazoline)-based copolymer was used to study the interaction between acetaminophen (APAP) and bovine serum albumin (BSA) by frontal analysis capillary electrophoresis (FACE). The star-shaped copolymer, poly(ethylene imine)-graft-poly(2-methyl-2-oxazoline) (PEI-g-PMOXA), was immobilized onto the fused-silica capillary inner wall via dopamine-assisted co-deposition strategy, yielding a PEI-g-PMOXA/polydopamine (PDA)-coated antifouling capillary, i.e., an antifouling capillary coated with the PEI-g-PMOXA/PDA co-deposited film. Electroosmotic flow (EOF) mobility of the PEI-g-PMOXA/PDA-coated capillary was almost zero in a wide pH range (3.0-10.0), while the EOF mobility of bare capillary was much larger and increased significantly with pH increasing. When the PEI-g-PMOXA/PDA-coated capillary was exploited to separate a protein mixture including cytochrome c, lysozyme, ribonuclease A and α-chymotrypsinogen A, the theoretical plate numbers were of five orders of magnitude which were about ten-fold higher over those obtained with bare capillary; in addition, the RSD values of migration time were mostly less than 0.7% (30 consecutive runs) which were much smaller than those of bare capillary (c.a. 5.7%). The protein-resistant PEI-g-PMOXA/PDA-coated capillary was then used to investigate the interaction between APAP and BSA by FACE, the binding constant and number of binding sites at 25°C and pH 7.4 (Tris/HCl buffer of 25mM) were 1.39×10 4 M -1 and 1.08, respectively, which were comparable to the results determined by fluorescence spectroscopic measurement (3.18×10 4 M -1 and 1.19, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

Signals of El Niño Modoki in the tropical tropopause layer and stratosphere

NASA Astrophysics Data System (ADS)

Xie, F.; Li, J.; Tian, W.; Feng, J.

2012-02-01

The effects of El Niño Modoki events on the tropical tropopause layer (TTL) and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF) reanalysis data, satellite observations from the Aura satellite Microwave Limb Sounder (MLS), oceanic El Niño indices, and general climate model outputs. El Niño Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pacific upper troposphere. The spatial patterns of the outgoing longwave radiation (OLR) and upper tropospheric water vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF) analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Niño events are associated with the leading mode of the EOF, while El Niño Modoki events correspond to the second mode. El Niño Modoki activities tend to moisten the lower and middle stratosphere, but dry the upper stratosphere. It was also found that the canonical El Niño signal can overlay linearly on the QBO signal in the stratosphere, whereas the interaction between the El Niño Modoki and QBO signals is non-linear. Because of these non-linear interactions, El Niño Modoki events have a reverse effect on high latitudes stratosphere, as compared with the effects of typical Modoki events, i.e. the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Niño Modoki events. However, simulations suggest that canonical El Niño and El Niño Modoki activities actually have the same influence on high latitudes stratosphere, in the absence of interactions between QBO and ENSO signals. The present results also reveal that canonical El Niño events have a greater impact on the high-latitude Northern Hemisphere stratosphere than on the high-latitude Southern Hemisphere stratosphere. However, El Niño Modoki events can more profoundly influence the high-latitude Southern Hemisphere stratosphere than the high-latitude Northern Hemisphere stratosphere.

The northern annular mode in summer and its relation to solar activity variations in the GISS ModelE

NASA Astrophysics Data System (ADS)

Lee, Jae N.; Hameed, Sultan; Shindell, Drew T.

2008-03-01

The northern annular mode (NAM) has been successfully used in several studies to understand the variability of the winter atmosphere and its modulation by solar activity. The variability of summer circulation can also be described by the leading empirical orthogonal function (EOF) of geopotential heights. We compare the annular modes of the summer geopotential heights in the northern hemisphere stratosphere and troposphere in the Goddard Institute for Space Studies (GISS) ModelE with those in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both model and observation suggests that the summer stratosphere is more "summer-like" when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The temperature fluctuations in simulated solar minimum conditions are greater than in solar maximum throughout the summer stratosphere. The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum variability over the Asian monsoon region. The corresponding EOF in ModelE has a qualitatively similar structure but with less variability in the Asian monsoon region which is displaced eastward of its observed position. In both the NCEP/NCAR reanalysis and the GCM the negative anomalies associated with the NAM in the Euro-Atlantic and Aleutian island regions are enhanced in the solar minimum conditions, though the results are not statistically significant.

Regional application of multi-layer artificial neural networks in 3-D ionosphere tomography

NASA Astrophysics Data System (ADS)

Ghaffari Razin, Mir Reza; Voosoghi, Behzad

2016-08-01

Tomography is a very cost-effective method to study physical properties of the ionosphere. In this paper, residual minimization training neural network (RMTNN) is used in voxel-based tomography to reconstruct of 3-D ionosphere electron density with high spatial resolution. For numerical experiments, observations collected at 37 GPS stations from Iranian permanent GPS network (IPGN) are used. A smoothed TEC approach was used for absolute STEC recovery. To improve the vertical resolution, empirical orthogonal functions (EOFs) obtained from international reference ionosphere 2012 (IRI-2012) used as object function in training neural network. Ionosonde observations is used for validate reliability of the proposed method. Minimum relative error for RMTNN is 1.64% and maximum relative error is 15.61%. Also root mean square error (RMSE) of 0.17 × 1011 (electrons/m3) is computed for RMTNN which is less than RMSE of IRI2012. The results show that RMTNN has higher accuracy and compiles speed than other ionosphere reconstruction methods.

Winter Precipitation in North America and the Pacific-North America Pattern in GEOS-S2Sv2 Seasonal Hindcast

NASA Technical Reports Server (NTRS)

Li, Zhao; Molod, Andrea; Schubert, Siegfried

2018-01-01

Reliable prediction of precipitation remains one of the most pivotal and complex challenges in seasonal forecasting. Previous studies show that various large-scale climate modes, such as ENSO, PNA and NAO play significant role in winter precipitation variability over the Northern America. The influences are most pronounced in years of strong indices of such climate modes. This study evaluates model bias, predictability and forecast skills of monthly winter precipitation in GEOS5-S2S 2.0 retrospective forecast from 1981 to 2016, with emphasis on the forecast skill of precipitation over North America during the extreme events of ENSO, PNA and NAO by applying EOF and composite analysis.

Migration behavior of organic dyes based on physicochemical properties of solvents as background electrolytes in non-aqueous capillary electrophoresis.

PubMed

Gu, Minjeong; Cho, Keunchang; Kang, Seong Ho

2018-07-27

The migration behavior of organic fluorescent dyes (i.e., crystal violet, methyl violet base, methyl violet B base, rhodamine 6G, and rhodamine B base) in non-aqueous capillary electrophoresis (NACE) was investigated by focusing on the physicochemical properties of various organic solvents [ethanol, methanol, 2-propanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)] in background electrolyte (BGE). Laser-induced fluorescence (LIF) and UV/Vis detectors were employed to observe both the migration time of organic dyes and the electroosmotic flow (EOF) in NACE, respectively. As seen in conventional aqueous BGE, the mobility of EOF in organic solvents tended to rise when the ratio between the dielectric constant and the solvent's viscosity (ε/η) increased in accordance with Smoluchowski's equation. However, unlike the ε/η of pure organic solvents, the migration order of dyes changed as follows: methanol (60.0) > DMF (45.8) > ethanol (22.8) > DMSO (23.4) > 2-propanol (9.8). Since the amount of acetic acid added to balance the pH depends on the pK a of each solvent, EOF changed when the difference in the ε/η value was small. This resulted from the inhibition of mobility, and its difference was dependent on the ε/η of BGEs with high ionic strength. In particular, the actual mobility of dyes in DMF showed excellent compliance with the Debye-Hückel-Onsager (DHO) theory extended by Falkenhagen and Pitts, which enabled us to analyze all dyes within 15 min with excellent resolution (R s >  2.5) under optimum NACE conditions (10 mM sodium borate and 4661 mM acetic acid in 100% DMF, pH 4.5). In addition, the NACE method was successfully applied for analyzing commercially available ballpoint ink pens. Thus, these results could be used to anticipate the migration order of organic dyes in a 100% NACE separation system. Copyright © 2018 Elsevier B.V. All rights reserved.

Cryohemolysis, erythrocyte osmotic fragility, and supplementary hematimetric indices in the diagnosis of hereditary spherocytosis

PubMed Central

Emilse, Ledesma Achem Miryam; Cecilia, Haro; María, Terán Magdalena; Eugenia, Mónaco María; Alicia, Issé Blanca

2018-01-01

Background Hereditary spherocytosis (HS) is a chronic hemolytic anemia characterized by microspherocytes in the peripheral blood and increased erythrocyte osmotic fragility (EOF). This study evaluated the cryohemolysis test (CHT); initial hemolysis (IH); immediate and incubated hemolysis percentage in 5.5 g/L NaCl (H5.5); mean corpuscular hemoglobin concentration (MCHC); red blood cell distribution width (RDW); and Hb/MCHC, Hb/RDW, and MCHC/RDW ratios for the diagnosis of HS. Methods Data from 13 patients with HS were evaluated at the Instituto de Bioquímica Aplicada and compared with data from 14 unaffected individuals and 11 patients with anemia due to another etiology. Total blood and reticulocyte counts, CHT, and immediate and incubated EOF were performed in all subjects; sensitivity, specificity, efficiency, and Youden index (YI) were calculated. Results Eight patients with HS had MCHC ≥345 g/L, 10 had RDW ≥14.5%, 12 had IH >5.0 g/L, 11 had immediate H5.5 ≥5%, and 13 had incubated H5.5 ≥50% (the cut-off value to consider HS). The efficiency and YI were: immediate H5.5 (0.94–0.85), incubated H5.5 (0.89–0.82), IH (0.89–0.78), MCHC (0.87–0.62), CHT (0.84–0.54), and Hb/MCHC (0.71–0.56), respectively. The calculated ratios could distinguish subjects with HS from unaffected individuals (P<0.05), but not those with anemia of another etiology (P>0.05). Conclusion Although the CHT and supplementary hematimetric indexes were useful to differentiate individuals with SH from healthy controls, they cannot distinguish from anemias of other etiology. CHT and MCHC, in addition to EOF, are recommended for diagnosing HS patients because of their low cost and efficiency. PMID:29662857

[Recent advances and applications of capillary electrochromatography and pressurized capillary electrochromatography].

PubMed

Wu, Yi; Zhang, Xiaohui; Wei, Juan; Xue, Yunyun; Bahatibieke, Marjan; Wang, Yan; Yan, Chao

2009-09-01

Capillary electrochromatography (CEC), in which electroosmotic flow (EOF) created from the electrical double layer is made to act as a pump to drive the mobile phase in a capillary column packed with micro-particulates or coated with stationary phase. Both neutral and charged species can be resolved by CEC. It has been demonstrated that the efficiency of a separation obtained by electroosmotic propulsion is superior to that obtained by pressure-driven flow (as is the case in HPLC). CEC combines the best features of CE and versatile selectivity and large sample capacity of HPLC, promising high efficiency, high resolution, high selectivity and high peak capacity. However, in practice, when CEC is used without pressure, often used on a commercial CE instrument, there are problems and difficulties associated with bubbles formation and column dry-out. These difficulties can be overcome by a pressurized CEC (pCEC) system, in which a supplementary pressure is applied to the column in addition to the EOF. In such a system, a pressure can be applied to the capillary column to suppress bubbles formation. Quantitative sample introduction in pCEC can be easily achieved through a rotary-type injector. Most importantly, it is amenable for a solvent gradient mode, similar to that in HPLC, by programming the composition of mobile phase. The article brings a comprehensive survey of recent development of CEC and pCEC, including the development of instrumentation, capillary columns and stationary phase as well as CEC and pCEC applications in life science, biotechnology, pharmaceutical analysis, food safety and environmental security. Prospects for CEC and pCEC development and application are also discussed.

Comments on `A Cautionary Note on the Interpretation of EOFs'.

NASA Astrophysics Data System (ADS)

Behera, Swadhin K.; Rao, Suryachandra A.; Saji, Hameed N.; Yamagata, Toshio

2003-04-01

The misleading aspect of the statistical analyses used in Dommenget and Latif, which raises concerns on some of the reported climate modes, is demonstrated. Adopting simple statistical techniques, the physical existence of the Indian Ocean dipole mode is shown and then the limitations of varimax and regression analyses in capturing the climate mode are discussed.

Submesoscale Structure of the California Current Near San Clemente Island

DTIC Science & Technology

1990-06-01

components at the 8 km line in figure 9 p• p - e 0 Fi u eOFS JSlIE DIS TAIIC I |MI .: ..- 1111 O, AIF | KA Figrellh. Vertical cross-section of standard...7. Huyer, Adriana and P. Michael Kosro, Mesoscale Surveys over the Shelf and Slope in the Upwelling Region Near Point Arena, California, J. Geophs

A New 1DVAR Retrieval for AMSR2 and GMI: Validation and Sensitivites

NASA Astrophysics Data System (ADS)

Duncan, D.; Kummerow, C. D.

2015-12-01

A new non-raining retrieval has been developed for microwave imagers and applied to the GMI and AMSR2 sensors. With the Community Radiative Transfer Model (CRTM) as the forward model for the physical retrieval, a 1-dimensional variational method finds the atmospheric state which minimizes the difference between observed and simulated brightness temperatures. A key innovation of the algorithm development is a method to calculate the sensor error covariance matrix that is specific to the forward model employed and includes off-diagonal elements, allowing the algorithm to handle various forward models and sensors with little cross-talk. The water vapor profile is resolved by way of empirical orthogonal functions (EOFs) and then summed to get total precipitable water (TPW). Validation of retrieved 10m wind speed, TPW, and sea surface temperature (SST) is performed via comparison with buoys and radiosondes as well as global models and other remotely sensed products. In addition to the validation, sensitivity experiments investigate the impact of ancillary data on the under-constrained retrieval, a concern for climate data records that strive to be independent of model biases. The introduction of model analysis data is found to aid the algorithm most at high frequency channels and affect TPW retrievals, whereas wind and cloud water retrievals show little effect from ingesting further ancillary data.

Leading modes of tropical Pacific subsurface ocean temperature and associations with two types of El Niño.

PubMed

Zhang, Zhiyuan; Ren, Baohua; Zheng, Jianqiu

2017-02-17

Using empirical orthogonal function (EOF) analysis of the monthly tropical Pacific subsurface ocean temperature anomalies (SOTA) from 1979 to 2014, we detected three leading modes in the tropical Pacific subsurface temperature. The first mode has a dipole pattern, with warming in the eastern Pacific and cooling in the western Pacific, and is closely related to traditional El Niño. The second mode has a monopole pattern, with only warming in the central Pacific subsurface. The third mode has a zonal tripole pattern, with warming in the off-equatorial central Pacific and cooling in the far eastern Pacific and western Pacific. The second and third modes are both related to El Niño Modoki. Mode 1 is linked with a Kelvin wave that propagates from the central to the eastern Pacific and is induced by the anomalous westerlies that propagate from the western to the central Pacific. Mode 2 is also linked with a Kelvin wave that propagates from the western to the central Pacific induced by the enhancement of westerlies over the western Pacific. Mode 3 is linked with a Rossby wave that propagates from the central to the western Pacific driven by the anomalous easterlies over the eastern Pacific.

cBathy: A robust algorithm for estimating nearshore bathymetry

USGS Publications Warehouse

Plant, Nathaniel G.; Holman, Rob; Holland, K. Todd

2013-01-01

A three-part algorithm is described and tested to provide robust bathymetry maps based solely on long time series observations of surface wave motions. The first phase consists of frequency-dependent characterization of the wave field in which dominant frequencies are estimated by Fourier transform while corresponding wave numbers are derived from spatial gradients in cross-spectral phase over analysis tiles that can be small, allowing high-spatial resolution. Coherent spatial structures at each frequency are extracted by frequency-dependent empirical orthogonal function (EOF). In phase two, depths are found that best fit weighted sets of frequency-wave number pairs. These are subsequently smoothed in time in phase 3 using a Kalman filter that fills gaps in coverage and objectively averages new estimates of variable quality with prior estimates. Objective confidence intervals are returned. Tests at Duck, NC, using 16 surveys collected over 2 years showed a bias and root-mean-square (RMS) error of 0.19 and 0.51 m, respectively but were largest near the offshore limits of analysis (roughly 500 m from the camera) and near the steep shoreline where analysis tiles mix information from waves, swash and static dry sand. Performance was excellent for small waves but degraded somewhat with increasing wave height. Sand bars and their small-scale alongshore variability were well resolved. A single ground truth survey from a dissipative, low-sloping beach (Agate Beach, OR) showed similar errors over a region that extended several kilometers from the camera and reached depths of 14 m. Vector wave number estimates can also be incorporated into data assimilation models of nearshore dynamics.

Southern Indian Ocean SST as a modulator for the progression of Indian summer monsoon

NASA Astrophysics Data System (ADS)

Shahi, Namendra Kumar; Rai, Shailendra; Mishra, Nishant

2018-01-01

This study explores the possibility of southern Indian Ocean (SIO) sea surface temperature (SST) as a modulator for the early phase of Indian summer monsoon and its possible physical mechanism. A dipole-like structure is obtained from the empirical orthogonal function (EOF) analysis which is similar to an Indian Ocean subtropical dipole (IOSD) found earlier. A subtropical dipole index (SDI) is defined based on the SST anomaly over the positive and negative poles. The regression map of rainfall over India in the month of June corresponding to the SDI during 1983-2013 shows negative patterns along the Western Ghats and Central India. However, the regression pattern is insignificant during 1952-1982. The multiple linear regression models and partial correlation analysis also indicate that the SDI acts as a dominant factor to influence the rainfall over India in the month of June during 1983-2013. The similar result is also obtained with the help of composite rainfall over the land points of India in the month of June for positive (negative) SDI events. It is also observed that the positive (negative) SDI delays (early) the onset dates of Indian monsoon over Kerala during the time domain of our study. The study is further extended to identify the physical mechanism of this impact, and it is found that the heating (cooling) in the region covering SDI changes the circulation pattern in the SIO and hence impacts the progression of monsoon in India.

Examining the Complexity of Educational Attainment for Black Males in an Educational Opportunity Fund Program at a Community College

ERIC Educational Resources Information Center

Williams, LaVon A.

2017-01-01

The purpose of this research is to describe the lived experience of Black males in an Educational Opportunity Fund (EOF) program at a community college. According to research, community colleges are the first option for many Black male students who are underprepared academically and come from low socioeconomic backgrounds. This phenomenological…

Estimating mass balances of the global water reservoirs by GRACE satellite gravimetry

NASA Astrophysics Data System (ADS)

Ramillien, G.; Lombard, A.; Cazenave, A.

2004-12-01

According to global hydrology models, the total water storage on the continents continuously decreases with time. In order to verify this scenario of a global and progressive transfer of water mass between the atmosphere, the oceans and the continents, we estimated and analysed the time-variations of the water mass in these water mass reservoirs for a recent period of time by space gravimetry. For this purpose, we used the monthly GRACE geoids recently released by CSR and GFZ (04/2002-05/2004). The spatial resolution of the GRACE solutions was unfortunately limited to degree 10-15 (around 2000 km) by the presence of noise for the higher harmonic degrees. The water mass changes were also analysed using Empirical Othogonal Functions (EOFs) decompositions for characterizing the main modes of mass variability for each water reservoirs at seasonal and inter-annual time scales.

Towards high concentration enhancement of microfluidic temperature gradient focusing of sample solutes using combined AC and DC field induced Joule heating.

PubMed

Ge, Zhengwei; Wang, Wei; Yang, Chun

2011-04-07

It is challenging to continuously concentrate sample solutes in microfluidic channels. We present an improved electrokinetic technique for enhancing microfluidic temperature gradient focusing (TGF) of sample solutes using combined AC and DC field induced Joule heating effects. The introduction of an AC electric field component services dual functions: one is to produce Joule heat for generating temperature gradient; the other is to suppress electroosmotic flow. Consequently the required DC voltages for achieving sample concentration by Joule heating induced TGF are reduced, thereby leading to smaller electroosmotic flow (EOF) and thus backpressure effects. As a demonstration, the proposed technique can lead to concentration enhancement of sample solutes of more than 2500-fold, which is much higher than the existing literature reported microfluidic concentration enhancement by utilizing the Joule heating induced TGF technique.

Surface retrievals from Hyperion EO1 using a new, fast, 1D-Var based retrieval code

NASA Astrophysics Data System (ADS)

Thelen, Jean-Claude; Havemann, Stephan; Wong, Gerald

2015-05-01

We have developed a new algorithm for the simultaneous retrieval of the atmospheric profiles (temperature, humidity, ozone and aerosol) and the surface reflectance from hyperspectral radiance measurements obtained from air/space-borne, hyperspectral imagers such as Hyperion EO-1. The new scheme, proposed here, consists of a fast radiative transfer code, based on empirical orthogonal functions (EOFs), in conjunction with a 1D-Var retrieval scheme. The inclusion of an 'exact' scattering code based on spherical harmonics, allows for an accurate treatment of Rayleigh scattering and scattering by aerosols, water droplets and ice-crystals, thus making it possible to also retrieve cloud and aerosol optical properties, although here we will concentrate on non-cloudy scenes. We successfully tested this new approach using hyperspectral images taken by Hyperion EO-1, an experimental pushbroom imaging spectrometer operated by NASA.

System Learning via Exploratory Data Analysis: Seeing Both the Forest and the Trees

NASA Astrophysics Data System (ADS)

Habash Krause, L.

2014-12-01

As the amount of observational Earth and Space Science data grows, so does the need for learning and employing data analysis techniques that can extract meaningful information from those data. Space-based and ground-based data sources from all over the world are used to inform Earth and Space environment models. However, with such a large amount of data comes a need to organize those data in a way such that trends within the data are easily discernible. This can be tricky due to the interaction between physical processes that lead to partial correlation of variables or multiple interacting sources of causality. With the suite of Exploratory Data Analysis (EDA) data mining codes available at MSFC, we have the capability to analyze large, complex data sets and quantitatively identify fundamentally independent effects from consequential or derived effects. We have used these techniques to examine the accuracy of ionospheric climate models with respect to trends in ionospheric parameters and space weather effects. In particular, these codes have been used to 1) Provide summary "at-a-glance" surveys of large data sets through categorization and/or evolution over time to identify trends, distribution shapes, and outliers, 2) Discern the underlying "latent" variables which share common sources of causality, and 3) Establish a new set of basis vectors by computing Empirical Orthogonal Functions (EOFs) which represent the maximum amount of variance for each principal component. Some of these techniques are easily implemented in the classroom using standard MATLAB functions, some of the more advanced applications require the statistical toolbox, and applications to unique situations require more sophisiticated levels of programming. This paper will present an overview of the range of tools available and how they might be used for a variety of time series Earth and Space Science data sets. Examples of feature recognition from both 1D and 2D (e.g. imagery) time series data sets will be presented.

Atmospheric Teleconnections From Cumulants

NASA Astrophysics Data System (ADS)

Sabou, F.; Kaspi, Y.; Marston, B.; Schneider, T.

2011-12-01

Multi-point cumulants of fields such as vorticity provide a way to visualize atmospheric teleconnections, complementing other approaches such as the method of empirical orthogonal functions (EOFs). We calculate equal-time two-point cumulants of the vorticity from NCEP reanalysis data during the period 1980 -- 2010 and from direct numerical simulation (DNS) using an idealized dry general circulation model (GCM) (Schneider and Walker, 2006). Extratropical correlations seen in the NCEP data are qualitatively reproduced by the model. Three- and four-point cumulants accumulated from DNS quantify departures of the probability distribution function from a normal distribution, shedding light on the efficacy of direct statistical simulation (DSS) of atmosphere dynamics by cumulant expansions (Marston, Conover, and Schneider, 2008; Marston 2011). Lagged-time two-point cumulants between temperature gradients and eddy kinetic energy (EKE), accumulated by DNS of an idealized moist aquaplanet GCM (O'Gorman and Schneider, 2008), reveal dynamics of storm tracks. Regions of enhanced baroclinicity (as found along the eastern boundary of continents) lead to a local enhancement of EKE and a suppression of EKE further downstream as the storm track self-destructs (Kaspi and Schneider, 2011).

A comparison between general circulation model simulations using two sea surface temperature datasets for January 1979

NASA Technical Reports Server (NTRS)

Ose, Tomoaki; Mechoso, Carlos; Halpern, David

1994-01-01

Simulations with the UCLA atmospheric general circulation model (AGCM) using two different global sea surface temperature (SST) datasets for January 1979 are compared. One of these datasets is based on Comprehensive Ocean-Atmosphere Data Set (COADS) (SSTs) at locations where there are ship reports, and climatology elsewhere; the other is derived from measurements by instruments onboard NOAA satellites. In the former dataset (COADS SST), data are concentrated along shipping routes in the Northern Hemisphere; in the latter dataset High Resolution Infrared Sounder (HIRS SST), data cover the global domain. Ensembles of five 30-day mean fields are obtained from integrations performed in the perpetual-January mode. The results are presented as anomalies, that is, departures of each ensemble mean from that produced in a control simulation with climatological SSTs. Large differences are found between the anomalies obtained using COADS and HIRS SSTs, even in the Northern Hemisphere where the datasets are most similar to each other. The internal variability of the circulation in the control simulation and the simulated atmospheric response to anomalous forcings appear to be linked in that the pattern of geopotential height anomalies obtained using COADS SSTs resembles the first empirical orthogonal function (EOF 1) in the control simulation. The corresponding pattern obtained using HIRS SSTs is substantially different and somewhat resembles EOF 2 in the sector from central North America to central Asia. To gain insight into the reasons for these results, three additional simulations are carried out with SST anomalies confined to regions where COADS SSTs are substantially warmer than HIRS SSTs. The regions correspond to warm pools in the northwest and northeast Pacific, and the northwest Atlantic. These warm pools tend to produce positive geopotential height anomalies in the northeastern part of the corresponding oceans. Both warm pools in the Pacific produce large-scale circulation anomalies with a pattern that resembles that obtained using COADS SSTs as well as EOF 1 of the control simulation; the warm pool in the Atlantic does not. These results suggest that the differences obtained with COADS SSTs and HIRS SSTs are mostly due to the differences in the datasets over the northern Pacific. There was a blocking episode near Greenland in late January 1979. Both simulations with warm SST anomalies over the northwest and northeast Pacific show a tendency toward increased incidence of North Atlantic blocking; the simulation with warm SST anomalies over the northwest Atlantic shows a tendency toward decreased incidence. These results suggest that features in both SST datasets that do not have a counterpart in the other dataset contribute signficantly to the differences between the simulated and observed fields. The results of this study imply that uncertainties in current SST distributions for the world oceans can be as important as the SST anomalies themselves in terms of their impact on the atmospheric circulation. Caution should be exercised, therefore, when linking anomalous circulation and SST patterns, especially in long-range prediction.

Quantifying the Influence of Dynamics Across Scales on Regional Climate Uncertainty in Western North America

NASA Astrophysics Data System (ADS)

Goldenson, Naomi L.

Uncertainties in climate projections at the regional scale are inevitably larger than those for global mean quantities. Here, focusing on western North American regional climate, several approaches are taken to quantifying uncertainties starting with the output of global climate model projections. Internal variance is found to be an important component of the projection uncertainty up and down the west coast. To quantify internal variance and other projection uncertainties in existing climate models, we evaluate different ensemble configurations. Using a statistical framework to simultaneously account for multiple sources of uncertainty, we find internal variability can be quantified consistently using a large ensemble or an ensemble of opportunity that includes small ensembles from multiple models and climate scenarios. The latter offers the advantage of also producing estimates of uncertainty due to model differences. We conclude that climate projection uncertainties are best assessed using small single-model ensembles from as many model-scenario pairings as computationally feasible. We then conduct a small single-model ensemble of simulations using the Model for Prediction Across Scales with physics from the Community Atmosphere Model Version 5 (MPAS-CAM5) and prescribed historical sea surface temperatures. In the global variable resolution domain, the finest resolution (at 30 km) is in our region of interest over western North America and upwind over the northeast Pacific. In the finer-scale region, extreme precipitation from atmospheric rivers (ARs) is connected to tendencies in seasonal snowpack in mountains of the Northwest United States and California. In most of the Cascade Mountains, winters with more AR days are associated with less snowpack, in contrast to the northern Rockies and California's Sierra Nevadas. In snowpack observations and reanalysis of the atmospheric circulation, we find similar relationships between frequency of AR events and winter season snowpack in the western United States. In spring, however, there is not a clear relationship between number of AR days and seasonal mean snowpack across the model ensemble, so caution is urged in interpreting the historical record in the spring season. Finally, the representation of the El Nino Southern Oscillation (ENSO)--an important source of interannual climate predictability in some regions--is explored in a large single-model ensemble using ensemble Empirical Orthogonal Functions (EOFs) to find modes of variance across the entire ensemble at once. The leading EOF is ENSO. The principal components (PCs) of the next three EOFs exhibit a lead-lag relationship with the ENSO signal captured in the first PC. The second PC, with most of its variance in the summer season, is the most strongly cross-correlated with the first. This approach offers insight into how the model considered represents this important atmosphere-ocean interaction. Taken together these varied approaches quantify the implications of climate projections regionally, identify processes that make snowpack water resources vulnerable, and seek insight into how to better simulate the large-scale climate modes controlling regional variability.

New multilayer coating using quaternary ammonium chitosan and κ-carrageenan in capillary electrophoresis: application in fast analysis of betaine and methionine.

PubMed

Vitali, Luciano; Della Betta, Fabiana; Costa, Ana Carolina O; Vaz, Fernando Antonio Simas; Oliveira, Marcone Augusto Leal; Vistuba, Jacqueline Pereira; Fávere, Valfredo T; Micke, Gustavo A

2014-06-01

The aim of this study was to develop a new multilayer coating with crosslinked quaternary ammonium chitosan (hydroxypropyltrimethyl ammonium chloride chitosan; HACC) and κ-carrageenan for use in capillary electrophoresis. A new semi-permanent multilayer coating was formed using the procedure developed and the method does not require the presence of polymers in the background electrolyte (BGE). The new capillary multilayer coating showed a cathodic electroosmotic flow (EOF) of around 30×10(-9) m(2) V(-1) s(-1) which is pH-independent in the range of pH 2 to 10. The enhanced EOF at low pH obtained contributed significantly to the development of a fast method of separation. The multilayer coating was then applied in the development of a fast separation method to determine betaine and methionine in pharmaceutical formulations by capillary zone electrophoresis (CZE). The BGE used to determine the betaine and methionine concentrations was composed of 10 mmol L(-1) tris(hydroxymethyl) aminomethane, 40 mmol L(-1) phosphoric acid and 10% (v/v) ethanol, at pH 2.1. A fused-silica capillary of 32 cm (50 µm ID×375 µm OD) was used in the experiments and samples and standards were analyzed employing the short-end injection procedure (8.5 cm effective length). The instrumental analysis time of the optimized method was 1.53 min (approx. 39 runs per hour). The validation of the proposed method for the determination of betaine and methionine showed good linearity (R(2)>0.999), adequate limit of detection (LOD <8 mg L(-1)) for the concentration in the samples and inter-day precision values lower than 3.5% (peak area and time migration). The results for the quantification of the amino acids in the samples determined by the CZE-UV method developed were statistically equal to those obtained with the comparative LC-MS/MS method according to the paired t-test with a confidence level of 95%. Copyright © 2014 Elsevier B.V. All rights reserved.

Tropical storm interannual and interdecadal variability in an ensemble of GCM integrations

NASA Astrophysics Data System (ADS)

Vitart, Frederic Pol.

1999-11-01

A T42L18 Atmospheric General Circulation Model forced by observed SSTs has been integrated for 10 years with 9 different initial conditions. An objective procedure for tracking model-generated tropical storms has been applied to this ensemble. Statistical tools have been applied to the ensemble frequency, intensity and location of tropical storms, leading to the conclusion that the potential predictability is particularly strong over the western North Pacific, the eastern North Pacific and the western North Atlantic. An EOF analysis of local SSts and a combined EOF analysis of vertical wind shear, 200 mb and 850 mb vorticity indicate that the simulated tropical storm interannual variability is mostly constrained by the large scale circulation as in observations. The model simulates a realistic interannual variability of tropical storms over the western North Atlantic, eastern North Pacific, western North Pacific and Australian basin where the model simulates a realistic large scale circulation. Several experiments with the atmospheric GCM forced by imposed SSTs demonstrate that the GCM simulates a realistic impact of ENSO on the simulated Atlantic tropical storms. In addition the GCM simulates fewer tropical storms over the western North Atlantic with SSTs of the 1950s than with SSTs of the 1970s in agreement with observations. Tropical storms simulated with RAS and with MCA have been compared to evaluate their sensitivity to a change in cumulus parameterization. Composites of tropical storm structure indicate stronger tropical storms with higher warm cores with MCA. An experiment using the GFDL hurricane model and several theoretical calculations indicate that the mean state may be responsible for the difference in intensity and in the height of the warm core. With the RAS scheme, increasing the threshold which determines when convection can occur increases the tropical storm frequency almost linearly. The increase of tropical storm frequency seems to be linked to an increase of CAPE. Tropical storms predicted by a coupled model produce a strong cooling of SSTs and their intensity is lower than in the simulations. An ensemble of coupled GCM integrations displays some skill in forecasting the tropical storm frequency when starting on July 1st.

Urban Thermodynamic Island in a Coastal City Analysed from an Optimized Surface Network

NASA Astrophysics Data System (ADS)

Pigeon, Grégoire; Lemonsu, Aude; Long, Nathalie; Barrié, Joël; Masson, Valéry; Durand, Pierre

2006-08-01

Within the framework of ESCOMPTE, a French experiment performed in June and July 2001 in the south-east of France to study the photo-oxidant pollution at the regional scale, the urban boundary layer (UBL) program focused on the study of the urban atmosphere over the coastal city of Marseille. A methodology developed to optimize a network of 20 stations measuring air temperature and moisture over the city is presented. It is based on the analysis of a numerical simulation, performed with the non-hydrostatic, mesoscale Meso-NH model, run with four nested-grids down to a horizontal resolution of 250 m over the city and including a specific parametrization for the urban surface energy balance. A three-day period was modelled and evaluated against data collected during the preparatory phase for the project in summer 2000. The simulated thermodynamic surface fields were analysed using an empirical orthogonal function (EOF) decomposition in order to determine the optimal network configuration designed to capture the dominant characteristics of the fields. It is the first attempt of application of this kind of methodology to the field of urban meteorology. The network, of 20 temperature and moisture sensors, was implemented during the UBL-ESCOMPTE experiment and continuously recorded data from 12 June to 14 July 2001. The measurements were analysed in order to assess the urban thermodynamic island spatio-temporal structure, also using EOF decomposition. During nighttime, the influence of urbanization on temperature is clear the field is characterized by concentric thermo-pleths around the old core of the city, which is the warmest area of the domain. The moisture field is more influenced by proximity to the sea and airflow patterns. During the day, the sea breeze often moves from west or south-west and consequently the spatial pattern for both parameters is characterized by a gradient perpendicular to the shoreline. Finally, in order to assess the methodology adopted, the spatial structures extracted from the simulation of the 2000 preparatory campaign and observations gathered in 2001 have been compared. They are highly correlated, which is a relevant validation of the methodology proposed. The relations between these spatial structures and geographical characteristics of the site have also been studied. High correlations between temperature spatial structure during nighttime and urban cover fraction or street aspect ratio are observed and simulated. For temperature during daytime or moisture during both daytime and nighttime these geographical factors are not correlated with thermodynamic fields spatial structures.

How predictable is the anomaly pattern of the Indian summer rainfall?

NASA Astrophysics Data System (ADS)

Li, Juan; Wang, Bin

2016-05-01

Century-long efforts have been devoted to seasonal forecast of Indian summer monsoon rainfall (ISMR). Most studies of seasonal forecast so far have focused on predicting the total amount of summer rainfall averaged over the entire India (i.e., all Indian rainfall index-AIRI). However, it is practically more useful to forecast anomalous seasonal rainfall distribution (anomaly pattern) across India. The unknown science question is to what extent the anomalous rainfall pattern is predictable. This study attempted to address this question. Assessment of the 46-year (1960-2005) hindcast made by the five state-of-the-art ENSEMBLE coupled dynamic models' multi-model ensemble (MME) prediction reveals that the temporal correlation coefficient (TCC) skill for prediction of AIRI is 0.43, while the area averaged TCC skill for prediction of anomalous rainfall pattern is only 0.16. The present study aims to estimate the predictability of ISMR on regional scales by using Predictable Mode Analysis method and to develop a set of physics-based empirical (P-E) models for prediction of ISMR anomaly pattern. We show that the first three observed empirical orthogonal function (EOF) patterns of the ISMR have their distinct dynamical origins rooted in an eastern Pacific-type La Nina, a central Pacific-type La Nina, and a cooling center near dateline, respectively. These equatorial Pacific sea surface temperature anomalies, while located in different longitudes, can all set up a specific teleconnection pattern that affects Indian monsoon and results in different rainfall EOF patterns. Furthermore, the dynamical models' skill for predicting ISMR distribution primarily comes primarily from these three modes. Therefore, these modes can be regarded as potentially predictable modes. If these modes are perfectly predicted, about 51 % of the total observed variability is potentially predictable. Based on understanding the lead-lag relationships between the lower boundary anomalies and the predictable modes, a set of P-E models is established to predict the principal component of each predictable mode, so that the ISMR anomaly pattern can be predicted by using the sum of the predictable modes. Three validation schemes are used to assess the performance of the P-E models' hindcast and independent forecast. The validated TCC skills of the P-E model here are more than doubled that of dynamical models' MME hindcast, suggesting a large room for improvement of the current dynamical prediction. The methodology proposed here can be applied to a wide range of climate prediction and predictability studies. The limitation and future improvement are also discussed.

New Science ang technology development about CSES and LAIC coupling mechanism

NASA Astrophysics Data System (ADS)

Zhang, X.; Zhao, S.; Zhou, C.; Ren, Z.; Wu, Y.

2016-12-01

China CSES satellite will be launched in 2017. There are eight scientific payloads onboard. In order to bring them into full play, some new technologies and science have been developed in data processing and LAIC coupling mechanism. Based on the GPS constellation, the assimilation model of ionosphere on Ne has been developed by using EOF method., where E and F layer have been calculated separately under different coordinate systems. Furthermore, the Hall and Pederson conductivity have been obtained at the altitude of 90-500km. By using the TBB receiver data, the ionospheric tomography technology has been developed by employing the methods of Truncated Singular Value Decomposition, Spherical Function and Empirical Orthogonal Function (EOF). On the basis of beacon receiver data in China, the Ne profiles along the observing links have been built up, and their temporal features have been studied. The full wave propagation model of VLF radio waves has been improved, and the two-dimensional calculating results are displayed to reveal the spatial distribution features of these radio waves. The actual observation on DEMETER satellite of ground transmitters is compared with the 2D theoretical results, and their consistence verifies the reliability of the model. By emitting the high power HF signals into the space, one can disturb and cause the heating phenomena in lower and topside ionosphere. Three heating events have been chosen out in SURA-DEMETER experiments. Based on the Ohmic heating theory, a 3D model has been constructed to simulate the heating process, in which the disturbed amplitudes in Ne are close to the actual observing under different ionospheric state. In the LAIC model related to earthquake research, the DC electric field coupling model has been paid more attention in recent years.Some simultaneous variation phenomena have been obtained around earthquakes. To explain these disturbances, the electric field model is suggested and improved, in which the additional current at the ground surface is considered. It is found that, vertical electric field is more obvious at low latitude and the horizontal electric field does not change with the height at high latitudes. The penetration height of LAI electric field in ionosphere is lower at low latitude than that at high latitude.

Predicting Trophic Interactions and Habitat Utilization in the California Current Ecosystem

DTIC Science & Technology

2015-09-30

spatial and temporal distribution of key marine organisms over multiple trophic levels, and (2) natural and anthropogenic variability in ecosystem...areas of climate modeling in upwelling regions (E. Curchitser), physical-biological modeling in the CCLME (J. Fiechter and C. Edwards), data...optimal growth conditions). By comparing interannual changes in fat depot against EOF modes for environmental variability (i.e., SST) and prey

Sustained Responses in Chronic Hepatitis B Patients with Nucleos(t)ide Analogue Drug-resistance after Peg-interferon Alfa-2a Add-on Treatment: A Long-term Cohort Study.

PubMed

Liu, Yunhua; Li, Weikun; Jia, Ting; Peng, Dan; Li, Huimin; Li, Xiaofei; Lv, Songqin

2018-03-28

Background and Aims: The use of additional nucleos(t)ide analogues (NAs) without cross-resistance to previously used NAs as a rescue therapy is recommended by most international guidelines for chronic hepatitis B patients with NA-resistance. We aimed to investigate the efficacy and safety of combination therapy of peg-interferon (PegIFN) alfa-2a and NA in these patients, comparing to those who switch to an alternative NA therapy without cross-resistance. Methods: In this prospective, comparative and cohort study, data were collected from the patients' hospital records. Eligible patients were those with hepatitis B e antigen (HBeAg) positivity and resistance to one or more NAs. All patients were treated with alternative NA alone or in combination with PegIFN alfa-2a for 52 weeks or 72 weeks, respectively. HBeAg seroconversion was measured at the end of follow-up (EOF; more than 104 weeks after the end of treatment). Results: Sixty-three patients were recruited to the cohort study (NA-therapy group = 31 patients; combination therapy group of NA and PegIFN alfa-2a = 32 patients). At the EOF, significantly more patients in the combination therapy group (13/27, 48.2%) achieved primary outcome of HBeAg seroconversion than those in the NA therapy group (4/32, 12.5%) ( p = 0.003). Four patients (14.8%) in the combination therapy group achieved hepatitis B surface antigen (HBsAg) loss and HBsAg seroconversion, but none in the NA therapy group did ( p = 0.039). In the combination therapy group, 16 patients (51.6%) achieved HBeAg seroconversion at the end of treatment, of which, 11 patients (68.8%) maintained the response until EOF. Conclusions: Adding on PegIFN alfa-2a in combination with NA therapy might be an appropriate rescue treatment option for patients who have prior NA resistance. In addition, combination therapy induced sustained off-treatment biochemical responses in these patients.

Characterization of Nanoparticles by Capillary Electrophoresis and Trapping of Nanoparticles in Microfluidics Device

DTIC Science & Technology

2009-08-01

tubular mode driven by electroosmotic flow and the inherent electrophoretic mobility of the analytes under the influence of an applied electric field...could be due to unlabeled beads. Figure 3 (C and D) also shows electropherogram of a neutral electroosmotic flow (EOF) marker dye BODIPY and...internal turbulent mixing . The current microfabricated electromagnets cannot produce sufficient fields to trap the NPs against a large flow forces

The Influence of Atmosphere-Ocean Interaction on MJO Development and Propagation

DTIC Science & Technology

2012-09-30

feedbacks and their influence on MJO development, and for forecasting of air sea interaction in the Indian Ocean basin and its influence on MJO. The...indicating precipitation maximum over the DYNAMO area and the red line indicating the precipitation anomaly west of Sumatra . The corresponding EOF...characterizing the November episode, relatively weaker October episode and convection situated in the eastern part of the Indian Ocean basin in December

The Influence of Atmosphere-Ocean Interaction on MJO Development and Propagation

DTIC Science & Technology

2012-09-30

atmosphere-ocean feedbacks and their influence on MJO development, and for forecasting of air sea interaction in the Indian Ocean basin and its influence...black line indicating precipitation maximum over the DYNAMO area and the red line indicating the precipitation anomaly west of Sumatra . The... basin in December. Similar EOF decomposition of the precipitation associated with Kelvin waves (not shown here) indicates strong Kelvin wave anomaly

A macrocyclic polyamine as an anion receptor in the capillary electrochromatographic separation of carbohydrates.

PubMed

Liu, Chuen-Ying; Chen, Tse-Hsien; Misra, Tarun Kumar

2007-06-22

An analytical approach of the 32-membered macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N8) was described for the capillary electrochromatographic (CEC) separation of derivatized mono- and disaccharides. The column displayed reversal electroosmotic flow (EOF) at pH below 7.0, while a cathodic EOF was shown at pH above 7.0. The reductive amination of saccharides was carried out with p-aminobenzoic acid. Some parameters that affect the CEC separations were investigated. Several competitive ligands, such as Tris, EDTA and phosphate were also examined for the effect on the performance. We achieved a complete separation of all compounds as well as the excess derivatizing agent by using borate buffer (pH 9.0) in a mode of concentration gradient (60 mM inlet side and 70 mM outlet side). The relative standard deviation of the retention time measured for each sample was less than 4% in six continuous runs, suggesting that the bonded phase along with the gradient formed inside the column was quite stable. With the mixing modes of anion coordination, anion exchange, and shape discrimination, the interaction adequately accomplishes the separation of carbohydrates which are epimers or have different glycosidic linkage, although the electrophoretic migration is also involved in the separation mechanism.

Effect of packing on changes in erythrocyte osmotic fragility and malondialdehyde concentration in donkeys administered with ascorbic acid.

PubMed

Olaifa, Folashade; Ayo, Joseph O; Ambali, Suleiman F; Rekwot, Peter I

2012-12-05

Experiments were performed with the aim of investigating the effect of packing on erythrocyte osmotic fragility (EOF) and malondialdehyde (MDA) concentration in donkeys, and the effect of ascorbic acid (AA). Twelve apparently healthy donkeys raised under the traditional extensive system served as experimental subjects. Six donkeys administered orally with AA (200 mg/kg) and subjected to packing were used as experimental animals, whilst six others not administered with AA served as controls. Blood samples were collected pre- and post-packing from all the donkeys for the determination of MDA and EOF. At 0.3% Sodium Chloride (NaCl) concentration, the percentage haemolysis was 93.69% ± 2.21% in the control donkeys and the value was significantly (P < 0.05) higher than the value of 71.31% ± 8.33%, recorded in the experimental donkeys. The post-packing MDA concentration obtained in the control donkeys was 39.62 µmol ± 4.16 µmol, and was not significantly different (P > 0.05) from the value of 35.97 µmol ± 2.88 µmol recorded in the experimental donkeys. In conclusion, the increase in haemolysis obtained in the donkeys suggested that packing induced oxidative stress, which was ameliorated by AA administration.

Assessment of polyelectrolyte coating stability under dynamic buffer conditions in CE.

PubMed

Swords, Kyleen E; Bartline, Peter B; Roguski, Katherine M; Bashaw, Sarah A; Frederick, Kimberley A

2011-09-01

Dynamic buffer conditions are present in many electrophoretically driven separations. Polyelectrolyte multilayer coatings have been employed in CE because of their chemical and physical stability as well as their ease of application. The goal of this study is to measure the effect of dynamic changes in buffer pH on flow using a real-time method for measuring EOF. Polyelectrolyte multilayers (PEMs) were composed of pairs of strong or completely ionized polyelectrolytes including poly(diallyldimethylammonium) chloride and poly(styrene sulfonate) and weak or ionizable polyelectrolytes including poly(allylamine) and poly(methacrylic acid). Polyelectrolyte multilayers of varying thicknesses (3, 4, 7, 8, 15, or 16 layers) were also studied. While the magnitude of the EOF was monitored every 2 s, the buffer pH was exchanged from a relatively basic pH (7.1) to increasingly acidic pHs (6.6, 6.1, 5.5, and 5.1). Strong polyelectrolytes responded minimally to changes in buffer pH (<1%), whereas substantial (>10%) and sometimes irreversible changes were measured with weak polyelectrolytes. Thicker coatings resulted in a similar magnitude of response but were more likely to degrade in response to buffer pH changes. The most stable coatings were formed from thinner layers of strong polyelectrolytes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The CE-Way of Thinking: "All Is Relative!".

PubMed

Schmitt-Kopplin, Philippe; Fekete, Agnes

2016-01-01

Over the last two decades the development of capillary electrophoresis instruments lead to systems with programmable sampler, separation column, separation buffer, and detection devices comparable visually in many aspects to the setup of classical chromatography.Two processes make capillary electrophoresis essentially different from chromatography and are the basis of the CE-way of thinking, namely, the injection type and the liquid flow within the capillary. (1) When the injection is made hydrodynamically (such as in most of the found applications in the literature), the injected volumes are directly dependent on the type and size of the separation capillary. (2) The buffer velocity is not pressure driven as in liquid chromatography but electrokinetically governed by the quality of the capillary surface (separation buffer dependant surface charge) inducing an electroosmotic flow (EOF). The EOF undergoes small variations and is not necessarily identical from one separation or day to the other. The direct consequence is an apparent nonreproducible migration time of the analytes, even though the own velocity of the ions is the same.The effective mobility (field strength normalized velocity) of the ions is a possible parameterization from acquired timescale to effective mobility-scale electropherograms leading to a reproducible visualization and better quantification with a direct relation to structural characters of the analytes (i.e., charge and size-see chapter on semiempirical modelization).

HadCM3 Simulations of ENSO behaviour during the Mid-Pliocene Warm Period

NASA Astrophysics Data System (ADS)

Bonham, S. G.; Haywood, A. M.; Lunt, D. J.

2009-04-01

It has been suggested that a permanent El Niño state existed during the mid-Pliocene (ca. 3.3 - 3.0 Ma BP), with a west-to-east temperature gradient in the tropical Pacific considerably weaker than today. This is based upon a number of palaeoceanographic studies which have examined the development of the thermocline and SST gradient in the tropical Pacific over the last five million years. This state is now being referred to as El Padre in recognition of the fact that a mean state warming in EEP SSTs does not necessarily imply the presence of a permanent El Niño. Recent results from mid-Pliocene coupled ocean-atmosphere model simulations have shown clear ENSO variability whilst maintaining the warming in the EEP. This research expands on this study, using the UK Met Office GCM (HadCM3), to examine the behaviour and characteristics of ENSO in two mid-Pliocene simulations (with an open and closed Central American Seaway, CAS) compared with a control pre-industrial run, as well as produce a detailed profile of the mean state climates. The results shown include timescales of ENSO variability across four regions in the Pacific, as well as frequency, EOF and wavelet analysis. We have also looked at the interaction of ENSO with the annual cycle and the onset of ENSO events, and the interdecadal variability in the simulations. The initial timeseries produced have shown a greater variability of ENSO during the closed CAS mid-Pliocene simulation where the system oscillates between events much more frequently than seen in the pre-industrial run. The EOF and wavelet analyses quantify this behaviour, showing that the variability is approximately 15% higher over the central and eastern equatorial Pacific, with a period of oscillation of 2-5 years compared with 4-8 years for the pre-industrial simulation. These results will be compared with those obtained from the second mid-Pliocene simulation (open CAS).

Spatial prediction of near surface soil water retention functions using hydrogeophysics and empirical orthogonal functions

NASA Astrophysics Data System (ADS)

Gibson, Justin; Franz, Trenton E.

2018-06-01

The hydrological community often turns to widely available spatial datasets such as the NRCS Soil Survey Geographic database (SSURGO) to characterize the spatial variability of soil properties. When used to spatially characterize and parameterize watershed models, this has served as a reasonable first approximation when lacking localized or incomplete soil data. Within agriculture, soil data has been left relatively coarse when compared to numerous other data sources measured. This is because localized soil sampling is both expensive and time intense, thus a need exists in better connecting spatial datasets with ground observations. Given that hydrogeophysics is data-dense, rapid, non-invasive, and relatively easy to adopt, it is a promising technique to help dovetail localized soil sampling with spatially exhaustive datasets. In this work, we utilize two common near surface geophysical methods, cosmic-ray neutron probe and electromagnetic induction, to identify temporally stable spatial patterns of measured geophysical properties in three 65 ha agricultural fields in western Nebraska. This is achieved by repeat geophysical observations of the same study area across a range of wet to dry field conditions in order to evaluate with an empirical orthogonal function. Shallow cores were then extracted within each identified zone and water retention functions were generated in the laboratory. Using EOF patterns as a covariate, we quantify the predictive skill of estimating soil hydraulic properties in areas without measurement using a bootstrap validation analysis. Results indicate that sampling locations informed via repeat hydrogeophysical surveys, required only five cores to reduce the cross-validation root mean squared error by an average of 64% as compared to soil parameters predicted by a commonly used benchmark, SSURGO and ROSETTA. The reduction to five strategically located samples within the 65 ha fields reduces sampling efforts by up to ∼90% as compared to the common practice of soil grid sampling every 1 ha.

Determination of Nitrate Carry-Over on Bytac(registered) Strips Via Capillary Electrophoresis

DTIC Science & Technology

2012-01-19

Beckman Coulter P/ ACE MDQ capillary electrophoresis instrument. A 60 cm long (10 cm effective length), 75 µm i.d. bare fused-silica capillary was used...the separation. Due to the high concentration of the BGE, electroosmotic flow (EOF) is significantly reduced allowing for the application of a...bromide) are not seen in the electropherogram due to the reversed polarity; electroosmotic flow suppression is sufficient to cause the ammonium and

Tomography Reconstruction of Ionospheric Electron Density with Empirical Orthonormal Functions Using Korea GNSS Network

NASA Astrophysics Data System (ADS)

Hong, Junseok; Kim, Yong Ha; Chung, Jong-Kyun; Ssessanga, Nicholas; Kwak, Young-Sil

2017-03-01

In South Korea, there are about 80 Global Positioning System (GPS) monitoring stations providing total electron content (TEC) every 10 min, which can be accessed through Korea Astronomy and Space Science Institute (KASI) for scientific use. We applied the computerized ionospheric tomography (CIT) algorithm to the TEC dataset from this GPS network for monitoring the regional ionosphere over South Korea. The algorithm utilizes multiplicative algebraic reconstruction technique (MART) with an initial condition of the latest International Reference Ionosphere-2016 model (IRI-2016). In order to reduce the number of unknown variables, the vertical profiles of electron density are expressed with a linear combination of empirical orthonormal functions (EOFs) that were derived from the IRI empirical profiles. Although the number of receiver sites is much smaller than that of Japan, the CIT algorithm yielded reasonable structure of the ionosphere over South Korea. We verified the CIT results with NmF2 from ionosondes in Icheon and Jeju and also with GPS TEC at the center of South Korea. In addition, the total time required for CIT calculation was only about 5 min, enabling the exploration of the vertical ionospheric structure in near real time.

Arctic Ocean Circulation Patterns Revealed by GRACE

NASA Astrophysics Data System (ADS)

Peralta-Ferriz, Cecilia; Morison, James H.; Wallace, John M.; Bonin, Jennifer A.; Zhang, Jinlun

2013-04-01

EOF analysis of non-seasonal, month-to-month variations in GRACE derived Arctic Ocean bottom pressure (OBP) yield three dominant modes. The first mode is a wintertime basin wide variation in mass associated with high atmospheric pressure (SLP) over Scandinavia. The second mode is a shift of mass from the central Arctic Ocean to the Siberian shelves due to low pressure over the basins, associated with the strength of the Arctic Oscillation. The third mode is a shift in mass between the Eastern and Western Siberian shelves, related to strength of the Beaufort High mainly in summer, and to eastward alongshore winds on the Barents Sea in winter. The PIOMAS and ECCO2 modeled OBP are consistent with the form of these modes and provide context in terms of variations in sea surface height. The models are used to investigate the ocean dynamics associated with each mode of OBP variability.

Reduced-Rank Array Modes of the California Current Observing System

NASA Astrophysics Data System (ADS)

Moore, Andrew M.; Arango, Hernan G.; Edwards, Christopher A.

2018-01-01

The information content of the ocean observing array spanning the U.S. west coast is explored using the reduced-rank array modes (RAMs) derived from a four-dimensional variational (4D-Var) data assimilation system covering a period of three decades. RAMs are an extension of the original formulation of array modes introduced by Bennett (1985) but in the reduced model state-space explored by the 4D-Var system, and reveal the extent to which this space is activated by the observations. The projection of the RAMs onto the empirical orthogonal functions (EOFs) of the 4D-Var background error correlation matrix provides a quantitative measure of the effectiveness of the measurements in observing the circulation. It is found that much of the space spanned by the background error covariance is unconstrained by the present ocean observing system. The RAM spectrum is also used to introduce a new criterion to prevent 4D-Var from overfitting the model to the observations.

Atmospheric correction of short-wave hyperspectral imagery using a fast, full-scattering 1DVar retrieval scheme

NASA Astrophysics Data System (ADS)

Thelen, J.-C.; Havemann, S.; Taylor, J. P.

2012-06-01

Here, we present a new prototype algorithm for the simultaneous retrieval of the atmospheric profiles (temperature, humidity, ozone and aerosol) and the surface reflectance from hyperspectral radiance measurements obtained from air/space-borne, hyperspectral imagers such as the 'Airborne Visible/Infrared Imager (AVIRIS) or Hyperion on board of the Earth Observatory 1. The new scheme, proposed here, consists of a fast radiative transfer code, based on empirical orthogonal functions (EOFs), in conjunction with a 1D-Var retrieval scheme. The inclusion of an 'exact' scattering code based on spherical harmonics, allows for an accurate treatment of Rayleigh scattering and scattering by aerosols, water droplets and ice-crystals, thus making it possible to also retrieve cloud and aerosol optical properties, although here we will concentrate on non-cloudy scenes. We successfully tested this new approach using two hyperspectral images taken by AVIRIS, a whiskbroom imaging spectrometer operated by the NASA Jet Propulsion Laboratory.

Inter-annual variability and long term predictability of exchanges through the Strait of Gibraltar

NASA Astrophysics Data System (ADS)

Boutov, Dmitri; Peliz, Álvaro; Miranda, Pedro M. A.; Soares, Pedro M. M.; Cardoso, Rita M.; Prieto, Laura; Ruiz, Javier; García-Lafuente, Jesus

2014-03-01

Inter-annual variability of calculated barotropic (netflow) and simulated baroclinic (inflow and outflow) exchanges through the Strait of Gibraltar is analyzed and their response to the main modes of atmospheric variability is investigated. Time series of the outflow obtained by high resolution simulations and estimated from in-situ Acoustic Doppler Current Profiler (ADCP) current measurements are compared. The time coefficients (TC) of the leading empirical orthogonal function (EOF) modes that describe zonal atmospheric circulation in the vicinity of the Strait (1st and 3rd of Sea-Level Pressure (SLP) and 1st of the wind) show significant covariance with the inflow and outflow. Based on these analyses, a regression model between these SLP TCs and outflow of the Mediterranean Water was developed. This regression outflow time series was compared with estimates based on current meter observations and the predictability and reconstruction of past exchange variability based on atmospheric pressure fields are discussed. The simple regression model seems to reproduce the outflow evolution fairly reasonably, with the exception of the year 2008, which is apparently anomalous without available physical explanation yet. The exchange time series show a reduced inter-annual variability (less than 1%, 2.6% and 3.1% of total 2-day variability, for netflow, inflow and outflow, respectively). From a statistical point of view no clear long-term tendencies were revealed. Anomalously high baroclinic fluxes are reported for the years of 2000-2001 that are coincident with strong impact on the Alboran Sea ecosystem. The origin of the anomalous flow is associated with a strong negative anomaly (~ - 9 hPa) in atmospheric pressure fields settled north of Iberian Peninsula and extending over the central Atlantic, favoring an increased zonal circulation in winter 2000/2001. These low pressure fields forced intense and durable westerly winds in the Gulf of Cadiz-Alboran system. The signal of this anomaly is also seen in time coefficients of the most significant EOF modes. The predictability of the exchanges for future climate is discussed.

CONSORT: Effects of adding adefovirdipivoxil to peginterferon alfa-2a at different time points on HBeAg-positivepatients: A prospective, randomized study.

PubMed

Zhang, Ka; Cao, Hong; Liang, Jiayi; Shu, Xin; Sun, Haixia; Li, Gang; Xu, Qihuan

2016-08-01

The aims of this study were to compare the efficacy and safety of the addition of adefovir dipivoxil (ADV) (started at different time points) to pegylated interferon alpha-2a (PEG-INF-α2a) and PEG-INF-α2a monotherapy. This prospective, randomized study sought to evaluate the safety and efficacy of the combination of PEG-INF-α2a and ADV at different time points.120 patients were randomized into groups that received PEG-INF-α2a as monotherapy (group A) or in combination with ADV started at week 0 (group B), 12 (group C), or 24 (group D). All patients were followed for 48 weeks. Efficacy and safety analyses were performed. Patients in group a received 135 μg of PEG-INF-α2a by subcutaneous injection once weekly for 48 weeks. Patients in the ADV add-on group received 135 μg of PEG-INF-α2a subcutaneously once weekly and received 10 mg of ADV administered once daily for 48 weeks. HBV DNA, HBsAg, HBeAg, and hepatitis B e antibody levels were determined. Responses were determined at week 12 (ADV add-on), the end of treatment for PEG-INF-α2a (48weeks) and ADV (EOT) and at the end of 96 weeks of follow-up (EOF). The rate of HBV DNA loss were higher in the combination groups than group A at the week 12, week 48, the EOT and EOF (P < 0.05). The rates of HBeAg seroconversion and HBsAg loss were similar among the treatment groups (P>0.05). The alanineaminotransferase (ALT) normalization rate was higher in the combination group than group A only at the EOT (P = 0.007). By the EOF, the patients with ADV added at week 12 achieved higher rates of HBV DNA loss (71.9%), HBeAg seroconversion (50.0%), HBsAg loss (15.6%), and ALT normalization (78.1%). PEG-INF-α2a plus ADV combination therapy is safe and superior to PEG-INF-α2amonotherapyfor decreasing serum HBV DNA and normalizing the ALT level but has no significant impact on the rate of HBeAg seroconversion and HBsAg loss. Adding ADV at week 12 may be an optimal combination strategy.

International Technology Transfer the Rope to Hang the West

DTIC Science & Technology

1989-03-28

order to provide awareness and appreciation of its importance to the security of the United States. DO R 1473 EOfTION OF V NOV 65 I.; OBSOLETE E - 7I... e Data Eme’e, USAWC MILITARY STUDIES PROGRAM PAPER INTERNATIONAL TECHNOLOGY TRANSFER The Rope To Hang The West AN INDIVIDUAL STUDY PROJECT Intended...notably the Departments of State, Commerce and Defense), and other friendly nations at odds with each other over competing demands and parochial interests

The Influence of Survey Methodology in Estimating Prevalence Rates of Childhood Sexual Abuse Among Navy Recruits

DTIC Science & Technology

2000-08-15

incidence and relationship to psychopathology. Child Abuse & Neglect, 18(5), 393-399. Cigrang, J. A., Carbone, E. G., Todd, S., & Fiedler, E...of college women. Child Abuse and Neglect, 10, 5-15. Haapasalo, J., & Pokela, E. (1999). Child- rearing and child abuse antecedents of...Research Center. Milner, J. S., Robertson, K. R., & Rogers, D. L. (1990). Childhood history of abuse and adult child abuse potential. Journal of Family

An Evaluation of the Effectiveness of the Crew Resource Management Programme in Naval Aviation

DTIC Science & Technology

2012-01-01

O’Connor* Centre for Innovation and Structural Change, J.E. Cairnes School of Business and Economics, National University of Ireland, Galway , Ireland E...of Ireland, Galway , as a Research Methodologist in July 2010. He received his PhD in Psychology from the University of Aberdeen, Scotland, in 2002...the US Navy, the Naval Postgraduate School, Naval Air Warfare Center, or the National University of Ireland, Galway . References Alkov, R.A. and

Effect of the Power Balance® band on static balance, hamstring flexibility, and arm strength in adults.

PubMed

Verdan, Princess J R; Marzilli, Thomas S; Barna, Geanina I; Roquemore, Anntionette N; Fenter, Brad A; Blujus, Brittany; Gosselin, Kevin P

2012-08-01

The purpose of this study was to determine the effect of Power Balance® bands on strength, flexibility, and balance. Strength and flexibility were measured using the MicroFit system. Strength was measured via a bicep curl and flexibility via the sit-and-reach method. Balance was measured by the BIODEX System SD. There were 4 different conditions for the balance test: eyes open on a firm surface (EOFS), eyes closed on a firm surface (ECFS), eyes open on a foam surface (EOFoS), and eyes closed on a foam surface (ECFoS). There were 24 subjects in the study (10 men and 14 women). A counterbalance, double-blind, placebo, controlled within-subject design was used. Each of the subjects participated in 3 treatment sessions, consisting of Power Balance®, placebo band, and no band. An alpha level of p ≤ 0.05 was set a priori. There were no significant differences in strength, flexibility, or balance with regard to the treatments used. There was a significant difference between the conditions in the balance test (p = 0.000): EOFS (0.51), ECFS (0.68), EOFoS (0.99), and ECFoS (2.18); however, these were independent of the treatment conditions. The results indicate that the Power Balance® bands did not have an effect on strength, flexibility, or balance.

Justification of rapid prototyping in the development cycle of thermoplastic-based lab-on-a-chip.

PubMed

Preywisch, Regina; Ritzi-Lehnert, Marion; Drese, Klaus S; Röser, Tina

2011-11-01

During the developmental cycle of lab-on-a-chip devices, various microstructuring techniques are required. While in the designing and assay implementation phase direct structuring or so-called rapid-prototyping methods such as milling or laser ablation are applied, replication methods like hot embossing or injection moulding are favourable for large quantity manufacturing. This work investigated the applicability of rapid-prototyping techniques for thermoplastic chip development in general, and the reproducibility of performances in dependency of the structuring technique. A previously published chip for prenatal diagnosis that preconcentrates DNA via electrokinetic trapping and field-amplified-sample-stacking and afterwards separates it in CGE was chosen as a model. The impact of structuring, sealing, and the integration of membranes on the mobility of the EOF, DNA preconcentration, and DNA separation was studied. Structuring methods were found to significantly change the location where preconcentration of DNA occurs. However, effects on the mobility of the EOF and the separation quality of DNA were not observed. Exchange of the membrane has no effect on the chip performance, whereas the sealing method impairs the separation of DNA within the chip. The overall assay performance is not significantly influenced by different structuring methods; thus, the application of rapid-prototyping methods during a chip development cycle is well justified. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The CE way of thinking: "all is relative!".

PubMed

Schmitt-Kopplin, Philippe; Fekete, Agnes

2008-01-01

Over the last two decades, the development of capillary electrophoresis (CE) instruments has lead to systems with programmable samplers, separation columns, separation buffers, and detection devices comparable visually in many aspects to the setup of classical chromatography. Two characteristics make CE essentially different from chromatography and are the basis of the CE way of thinking: first is the injection type and the liquid flow within the capillary. When the injection is made hydrodynamically (such as in most of the applications found in the literature), the injected volumes are directly dependent on the type and size of the separation capillary. The second characteristic is that in CE, buffer velocity is not pressure-driven, as in liquid chromatography, but is electrokinetically governed by the quality of the capillary surface (separation buffer dependent surface charge) inducing an electroosmotic flow (EOF). The EOF undergoes small variations and is not necessarily identical from one separation or day to the other. The direct consequence is that the migration time of the analytes apparently nonreproducible, although the velocity of the ions is the same. The effective mobility (field strength normalized velocity) of the ions is a possible parameterization from acquired time-scale to effective mobility-scale electropherograms leading to a reproducible visualization and better quantification with a direct relation to structural characters of the analytes (i.e., charge and size; see Chapter 23).

Echium Oil Reduces Plasma Triglycerides by Increasing Intravascular Lipolysis in apoB100-Only Low Density Lipoprotein (LDL) Receptor Knockout Mice

PubMed Central

Forrest, Lolita M.; Lough, Christopher M.; Chung, Soonkyu; Boudyguina, Elena Y.; Gebre, Abraham K.; Smith, Thomas L.; Colvin, Perry L.; Parks, John S.

2013-01-01

Echium oil (EO), which is enriched in SDA (18:4 n-3), reduces plasma triglyceride (TG) concentrations in humans and mice. We compared mechanisms by which EO and fish oil (FO) reduce plasma TG concentrations in mildly hypertriglyceridemic male apoB100-only LDLrKO mice. Mice were fed one of three atherogenic diets containing 0.2% cholesterol and palm oil (PO; 20%), EO (10% EO + 10% PO), or FO (10% FO + 10% PO). Livers from PO- and EO-fed mice had similar TG and cholesteryl ester (CE) content, which was significantly higher than in FO-fed mice. Plasma TG secretion was reduced in FO vs. EO-fed mice. Plasma very low density lipoprotein (VLDL) particle size was ordered: PO (63 ± 4 nm) > EO (55 ± 3 nm) > FO (40 ± 2 nm). Post-heparin lipolytic activity was similar among groups, but TG hydrolysis by purified lipoprotein lipase was significantly greater for EO and FO VLDL compared to PO VLDL. Removal of VLDL tracer from plasma was marginally faster in EO vs. PO fed mice. Our results suggest that EO reduces plasma TG primarily through increased intravascular lipolysis of TG and VLDL clearance. Finally, EO may substitute for FO to reduce plasma TG concentrations, but not hepatic steatosis in this mouse model. PMID:23857172

Echium oil reduces plasma triglycerides by increasing intravascular lipolysis in apoB100-only low density lipoprotein (LDL) receptor knockout mice.

PubMed

Forrest, Lolita M; Lough, Christopher M; Chung, Soonkyu; Boudyguina, Elena Y; Gebre, Abraham K; Smith, Thomas L; Colvin, Perry L; Parks, John S

2013-07-12

Echium oil (EO), which is enriched in SDA (18:4 n-3), reduces plasma triglyceride (TG) concentrations in humans and mice. We compared mechanisms by which EO and fish oil (FO) reduce plasma TG concentrations in mildly hypertriglyceridemic male apoB100-only LDLrKO mice. Mice were fed one of three atherogenic diets containing 0.2% cholesterol and palm oil (PO; 20%), EO (10% EO + 10% PO), or FO (10% FO + 10% PO). Livers from PO- and EO-fed mice had similar TG and cholesteryl ester (CE) content, which was significantly higher than in FO-fed mice. Plasma TG secretion was reduced in FO vs. EO-fed mice. Plasma very low density lipoprotein (VLDL) particle size was ordered: PO (63 ± 4 nm) > EO (55 ± 3 nm) > FO (40 ± 2 nm). Post-heparin lipolytic activity was similar among groups, but TG hydrolysis by purified lipoprotein lipase was significantly greater for EO and FO VLDL compared to PO VLDL. Removal of VLDL tracer from plasma was marginally faster in EO vs. PO fed mice. Our results suggest that EO reduces plasma TG primarily through increased intravascular lipolysis of TG and VLDL clearance. Finally, EO may substitute for FO to reduce plasma TG concentrations, but not hepatic steatosis in this mouse model.

Causes of Long-Term Drought in the United States Great Plains

NASA Technical Reports Server (NTRS)

Schubert, Siegfried D.; Suarez, Max J.; Pegion, Philip J.; Koster, Randal

2002-01-01

The United States Great Plains (USGP) experienced a number of multi-year droughts during the last century, most notably the droughts of the 1930s and 1950s. This study examines the causes of such droughts using ensembles of long term (1930-1999) simulations carried out with the NASA Seasonal-to-Interannual Prediction Project (NSIPP-1) atmospheric general circulation model (AGCM) forced with observed sea surface temperatures (SSTs). The results show that the model produces long-term (multi-year) variations in the USGP precipitation that are similar to those observed. A correlative analysis suggests that the ensemble mean low frequency (time scales longer than about 6 years) rainfall variations in the USGP are linked to a pan-Pacific pattern of SST variability that is the leading empirical orthogonal function (EOF) in the low frequency SST data. The link between the SST and the Great Plains precipitation is confirmed in idealized AGCM simulations, in which the model is forced by the 2 polarities of the pan-Pacific SST pattern. The idealized simulations further show that it is primarily the tropical part of the SST anomalies that influence the USGP. As such, the USGP tend to have above normal precipitation when the tropical Pacific SSTs are above normal, while there is a tendency for drought when the tropical SSTs are cold. The upper tropospheric response to the pan-Pacific SST EOF shows a global-scale pattern with a strong wave response in the Pacific and a substantial zonally-symmetric component in which USGP pluvial (drought) conditions are associated with reduced (enhanced) heights throughout the extra-tropics. The potential predictability of rainfall in the USGP associated with SSTs is rather modest, with on average about 1/3 of the total low frequency rainfall variance forced by SST anomalies. Further idealized experiments with climatological SST, suggest that the remaining low frequency variance in the USGP precipitation is the result of interactions with soil moisture. In particular, simulations with soil moisture feedback show a six-fold increase in the variance in annual USGP precipitation compared with simulations in which the soil feedback is excluded. In addition to increasing variance, the interactions with the soil introduce year-to-year memory in the hydrological cycle that is consistent with a red noise process, in which the low frequencies in the deep soil are the result of integrating a net forcing (precipitation-evaporation-runoff) that is white noise on interannual time scales. As such, the role of low frequency SST variability is to introduce a bias to the net forcing on the soil moisture that drives the random process preferentially to either wet or dry conditions.

Serum protein fractionation using supported molecular matrix electrophoresis.

PubMed

Dong, Weijie; Matsuno, Yu-ki; Kameyama, Akihiko

2013-08-01

Supported molecular matrix electrophoresis (SMME), in which a hydrophilic polymer such as PVA serves as a support within a porous PVDF membrane, was recently developed. This method is similar to cellulose acetate membrane electrophoresis but differs in the compatibility to glycan analysis of the separated bands. In this report, we describe the first instance of the application of SMME to human serum fractionation, and demonstrate the differences with serum fractionation by cellulose acetate membrane electrophoresis. The SMME membrane exhibited almost no EOF during electrophoresis, unlike the cellulose acetate membrane, but afforded comparative results for serum fractionation. The visualization of each fraction was achieved by conventional staining with dye such as Direct Blue-71, and objective quantification was obtained by densitometry after inducing membrane transparency with 1-nonene. Immunostaining was also achieved. Moreover, mass spectrometric analysis of both N-linked and O-linked glycans from the separated bands was demonstrated. Serum fractionation and glycan profiling of each fraction using SMME will enable novel insights into the relationships between various glycosylation profiles and disease states. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Finite element techniques in computational time series analysis of turbulent flows

NASA Astrophysics Data System (ADS)

Horenko, I.

2009-04-01

In recent years there has been considerable increase of interest in the mathematical modeling and analysis of complex systems that undergo transitions between several phases or regimes. Such systems can be found, e.g., in weather forecast (transitions between weather conditions), climate research (ice and warm ages), computational drug design (conformational transitions) and in econometrics (e.g., transitions between different phases of the market). In all cases, the accumulation of sufficiently detailed time series has led to the formation of huge databases, containing enormous but still undiscovered treasures of information. However, the extraction of essential dynamics and identification of the phases is usually hindered by the multidimensional nature of the signal, i.e., the information is "hidden" in the time series. The standard filtering approaches (like f.~e. wavelets-based spectral methods) have in general unfeasible numerical complexity in high-dimensions, other standard methods (like f.~e. Kalman-filter, MVAR, ARCH/GARCH etc.) impose some strong assumptions about the type of the underlying dynamics. Approach based on optimization of the specially constructed regularized functional (describing the quality of data description in terms of the certain amount of specified models) will be introduced. Based on this approach, several new adaptive mathematical methods for simultaneous EOF/SSA-like data-based dimension reduction and identification of hidden phases in high-dimensional time series will be presented. The methods exploit the topological structure of the analysed data an do not impose severe assumptions on the underlying dynamics. Special emphasis will be done on the mathematical assumptions and numerical cost of the constructed methods. The application of the presented methods will be first demonstrated on a toy example and the results will be compared with the ones obtained by standard approaches. The importance of accounting for the mathematical assumptions used in the analysis will be pointed up in this example. Finally, applications to analysis of meteorological and climate data will be presented.

Spatiotemporal variations of the twentieth century Tibetan Plateau precipitation based on the monthly 2.5° reconstructed data

NASA Astrophysics Data System (ADS)

Shen, Samuel S. P.; Clarke, Gregori; Shen, Bo-Wen; Yao, Tandong

2017-12-01

This paper studies the spatiotemporal variations of precipitation over the Tibetan Plateau (TP) region with latitude and longitude ranges of (25° N, 45° N) and (65° E, 105° E) of the twentieth century from January 1901-December 2000. A long-term (January 1901-December 2009) TP monthly precipitation dataset with 2.5° latitude-longitude resolution is generated in this paper using spectral optimal gridding (SOG) method. The method uses the Global Precipitation Climatology Center (GPCC) ground station data to anchor the basis of empirical orthogonal functions (EOFs) computed from the Global Precipitation Climatology Project (GPCP) data. Our gridding takes teleconnection into account and uses data from stations both within and outside of the TP region. While the annual total precipitation increased at an approximate rate of 2.6 mm per decade in the period of 1971-2000 exists, no significant increase of TP precipitation from 1901 to 2000 was found. Our rate is less than those of previous publications based only on the TP stations because our data consider the entire TP region, including desert and high-altitude areas. An analysis of extremes and spatiotemporal patterns of our data shows that our reconstructed data can properly quantify the reported disasters of flooding and droughts in India, Bangladesh, and China for the following events: flooding in 1988 and 1998 and drought in 1972. Our time-frequency analysis using the empirical mode decomposition method shows that our nonlinear trend agrees well with the linear trend in the period from 1971 to 2000. The spatiotemporal variation characteristics documented in this paper can help understand atmospheric circulations on TP precipitation and validate the TP precipitation in climate models.

Causing Factors for Extreme Precipitation in the Western Saudi-Arabian Peninsula

NASA Astrophysics Data System (ADS)

Alharbi, M. M.; Leckebusch, G. C.

2015-12-01

In the western coast of Saudi Arabia the climate is in general semi-arid but extreme precipitation events occur on a regular basis: e.g., on 26th November 2009, when 122 people were killed and 350 reported missing in Jeddah following more than 90mm in just four hours. Our investigation will a) analyse major drivers of the generation of extremes and b) investigate major responsible modes of variability for the occurrence of extremes. Firstly, we present a systematic analysis of station based observations of the most relevant extreme events (1985-2013) for 5 stations (Gizan, Makkah, Jeddah, Yenbo and Wejh). Secondly, we investigate the responsible mechanism on the synoptic to large-scale leading to the generation of extremes and will analyse factors for the time variability of extreme event occurrence. Extreme events for each station are identified in the wet season (Nov-Jan): 122 events show intensity above the respective 90th percentile. The most extreme events are systematically investigated with respect to the responsible forcing conditions which we can identify as: The influence of the Soudan Low, active Red-Sea-Trough situations established via interactions with mid-latitude tropospheric wave activity, low pressure systems over the Mediterranean, the influence of the North Africa High, the Arabian Anticyclone and the influence of the Indian monsoon trough. We investigate the role of dynamical forcing factors like the STJ and the upper-troposphere geopotential conditions and the relation to smaller local low-pressure systems. By means of an empirical orthogonal function (EOF) analysis based on MSLP we investigate the possibility to objectively quantify the influence of existing major variability modes and their role for the generation of extreme precipitation events.

MODIS observations of cyanobacterial risks in a eutrophic lake: Implications for long-term safety evaluation in drinking-water source.

PubMed

Duan, Hongtao; Tao, Min; Loiselle, Steven Arthur; Zhao, Wei; Cao, Zhigang; Ma, Ronghua; Tang, Xiaoxian

2017-10-01

The occurrence and related risks from cyanobacterial blooms have increased world-wide over the past 40 years. Information on the abundance and distribution of cyanobacteria is fundamental to support risk assessment and management activities. In the present study, an approach based on Empirical Orthogonal Function (EOF) analysis was used to estimate the concentrations of chlorophyll a (Chla) and the cyanobacterial biomarker pigment phycocyanin (PC) using data from the MODerate resolution Imaging Spectroradiometer (MODIS) in Lake Chaohu (China's fifth largest freshwater lake). The approach was developed and tested using fourteen years (2000-2014) of MODIS images, which showed significant spatial and temporal variability of the PC:Chla ratio, an indicator of cyanobacterial dominance. The results had unbiased RMS uncertainties of <60% for Chla ranging between 10 and 300 μg/L, and unbiased RMS uncertainties of <65% for PC between 10 and 500 μg/L. Further analysis showed the importance of nutrient and climate conditions for this dominance. Low TN:TP ratios (<29:1) and elevated temperatures were found to influence the seasonal shift of phytoplankton community. The resultant MODIS Chla and PC products were then used for cyanobacterial risk mapping with a decision tree classification model. The resulting Water Quality Decision Matrix (WQDM) was designed to assist authorities in the identification of possible intake areas, as well as specific months when higher frequency monitoring and more intense water treatment would be required if the location of the present intake area remained the same. Remote sensing cyanobacterial risk mapping provides a new tool for reservoir and lake management programs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Normal forms for reduced stochastic climate models

PubMed Central

Majda, Andrew J.; Franzke, Christian; Crommelin, Daan

2009-01-01

The systematic development of reduced low-dimensional stochastic climate models from observations or comprehensive high-dimensional climate models is an important topic for atmospheric low-frequency variability, climate sensitivity, and improved extended range forecasting. Here techniques from applied mathematics are utilized to systematically derive normal forms for reduced stochastic climate models for low-frequency variables. The use of a few Empirical Orthogonal Functions (EOFs) (also known as Principal Component Analysis, Karhunen–Loéve and Proper Orthogonal Decomposition) depending on observational data to span the low-frequency subspace requires the assessment of dyad interactions besides the more familiar triads in the interaction between the low- and high-frequency subspaces of the dynamics. It is shown below that the dyad and multiplicative triad interactions combine with the climatological linear operator interactions to simultaneously produce both strong nonlinear dissipation and Correlated Additive and Multiplicative (CAM) stochastic noise. For a single low-frequency variable the dyad interactions and climatological linear operator alone produce a normal form with CAM noise from advection of the large scales by the small scales and simultaneously strong cubic damping. These normal forms should prove useful for developing systematic strategies for the estimation of stochastic models from climate data. As an illustrative example the one-dimensional normal form is applied below to low-frequency patterns such as the North Atlantic Oscillation (NAO) in a climate model. The results here also illustrate the short comings of a recent linear scalar CAM noise model proposed elsewhere for low-frequency variability. PMID:19228943

A Combined EOF/Variational Approach for Mapping Radar-Derived Sea Surface Currents

DTIC Science & Technology

2011-01-01

Section 4 describes the results of experiments with the real observations off the Opal Coast of the Eastern English Channel. It is shown that the...To assess the method’s performance, we conducted twin-data experiments with simulated HFR data (Section 3) and real observations off the Opal Coast...the Opal coast of the Pas de Calais in northern France. 4.1. The data In May-June 2003. two HF radars were deployed to monitor surface currents

Lab on a Chip Packing of Submicron Particles for High Performance EOF Pumping

DTIC Science & Technology

2010-08-26

and wet etching techniques, using a soda lime glass substrate coated with chromium and photoresist (Nanofilm, Westlake Village, CA). A weir structure...observed previously for these soda lime glass microchips [8]. Images of the three segments of different sized particles con- tainedwithin the packed... Silica beads High pressure Lab on a chip a b s t r a c t The packing of submicrometer sized silica beads inside a microchannel was enabled by a novel

The Mesoscale Eddies and Kuroshio Transport in the Western North Pacific East of Taiwan from 8-year (2003-2010) Model Reanalysis

DTIC Science & Technology

2013-07-25

EOF . SVD 1 Introduction Mesoscale eddies are abundant in the ocean. Chelton et al. ( 2007 ), based on 10 years of altimetry sea surface height anomaly...transport. The dynamic height has a strong annual signal due to steric variations (Wang and Koblinsky 1996; Stammer 1997). Since our study is...JOE.2004.838334 Chelton DB, Schlax MG, Samelson RM, deSzoeke RA ( 2007 ) Global observations of large oceanic eddies. Geophys Res Lett 34, L15606. doi

Implementation of a reduced order Kalman filter to assimilate ocean color data into a coupled physical-biochemical model of the North Aegean Sea.

NASA Astrophysics Data System (ADS)

Kalaroni, Sofia; Tsiaras, Kostas; Economou-Amilli, Athena; Petihakis, George; Politikos, Dimitrios; Triantafyllou, George

2013-04-01

Within the framework of the European project OPEC (Operational Ecology), a data assimilation system was implemented to describe chlorophyll-a concentrations of the North Aegean, as well the impact on the European anchovy (Engraulis encrasicolus) biomass distribution provided by a bioenergetics model, related to the density of three low trophic level functional groups of zooplankton (heterotrophic flagellates, microzooplankton and mesozooplankton). The three-dimensional hydrodynamic-biogeochemical model comprises two on-line coupled sub-models: the Princeton Ocean Model (POM) and the European Regional Seas Ecosystem Model (ERSEM). The assimilation scheme is based on the Singular Evolutive Extended Kalman (SEEK) filter and its variant that uses a fixed correction base (SFEK). For the initialization, SEEK filter uses a reduced order error covariance matrix provided by the dominant Empirical Orthogonal Functions (EOF) of model. The assimilation experiments were performed for year 2003 using SeaWiFS chlorophyll-a data during which the physical model uses the atmospheric forcing obtained from the regional climate model HIRHAM5. The assimilation system is validated by assessing the relevance of the system in fitting the data, the impact of the assimilation on non-observed biochemical parameters and the overall quality of the forecasts.

Effects of surface roughness and electrokinetic heterogeneity on electroosmotic flow in microchannel

NASA Astrophysics Data System (ADS)

Masilamani, Kannan; Ganguly, Suvankar; Feichtinger, Christian; Bartuschat, Dominik; Rüde, Ulrich

2015-06-01

In this paper, a hybrid lattice-Boltzmann and finite-difference (LB-FD) model is applied to simulate the effects of three-dimensional surface roughness and electrokinetic heterogeneity on electroosmotic flow (EOF) in a microchannel. The lattice-Boltzmann (LB) method has been employed to obtain the flow field and a finite-difference (FD) method is used to solve the Poisson-Boltzmann (PB) equation for the electrostatic potential distribution. Numerical simulation of flow through a square cross-section microchannel with designed roughness is conducted and the results are critically analysed. The effects of surface heterogeneity on the electroosmotic transport are investigated for different roughness height, width, roughness interval spacing, and roughness surface potential. Numerical simulations reveal that the presence of surface roughness changes the nature of electroosmotic transport through the microchannel. It is found that the electroosmotic velocity decreases with the increase in roughness height and the velocity profile becomes asymmetric. For the same height of the roughness elements, the EOF velocity rises with the increase in roughness width. For the heterogeneously charged rough channel, the velocity profile shows a distinct deviation from the conventional plug-like flow pattern. The simulation results also indicate locally induced flow vortices which can be utilized to enhance the flow and mixing within the microchannel. The present study has important implications towards electrokinetic flow control in the microchannel, and can provide an efficient way to design a microfluidic system of practical interest.

Eddies in a bottleneck: an arbitrary Debye length theory for capillary electroosmosis.

PubMed

Park, Stella Y; Russo, Christopher J; Branton, Daniel; Stone, Howard A

2006-05-15

Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (kappa(-1)) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of eddies for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central eddies in very narrow constrictions at the scale of the Debye length. Eddies can be found both in the center of the channel and along the perimeter, and the presence of the eddies is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction.

Eddies in a Bottleneck: An Arbitrary Debye Length Theory for Capillary Electroosmosis

PubMed Central

Park, Stella Y.; Russo, Christopher J.; Branton, Daniel; Stone, Howard A.

2011-01-01

Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (κ−1) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of eddies for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central eddies in very narrow constrictions at the scale of the Debye length. Eddies can be found both in the center of the channel and along the perimeter, and the presence of the eddies is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction. PMID:16376361

The Sub-Polar Gyre Index - a community data set for application in fisheries and environment research

NASA Astrophysics Data System (ADS)

Berx, Barbara; Payne, Mark R.

2017-04-01

Scientific interest in the sub-polar gyre of the North Atlantic Ocean has increased in recent years. The sub-polar gyre has contracted and weakened, and changes in circulation pathways have been linked to changes in marine ecosystem productivity. To aid fisheries and environmental scientists, we present here a time series of the Sub-Polar Gyre Index (SPG-I) based on monthly mean maps of sea surface height. The established definition of the SPG-I is applied, and the first EOF (empirical orthogonal function) and PC (principal component) are presented. Sensitivity to the spatial domain and time series length are explored but found not to be important factors in terms of the SPG-I's interpretation. Our time series compares well with indices presented previously. The SPG-I time series is freely available online (http://dx.doi.org/10.7489/1806-1), and we invite the community to access, apply, and publish studies using this index time series.

Aircraft Configuration Noise Reduction. Volume 3. Computer Program Source Listing

DTIC Science & Technology

1976-06-01

CAT GEN 11 12=1 1+11 CATGtN 32 0360 REAOIKI,10CENIj=4C)(OT(J),.I=11,I2) CATCEN 33 REAO(KI, 100) fDI (JbJ=I#Ii) CATGtkN 34 IF (EOF(KI)) 4C9 20 CATGEN...CORE ANu IURBINE CGNVk 1 COMMON/COREIN/T13,PP3,cMF3,EX3,oELT3,J83, CONVR 13 CONVR 1’ C =5 EXIT FANC .,NVx i COMMUN/FANUAT/NSIG45,NLET45,NAFT45,1CP45,N845

A Numerical Study on the Influence of the Mid-Atlantic Ridge on Nonlinear Barotropic and First-Mode Baroclinic Rossby Waves Generated by Seasonal Winds.

DTIC Science & Technology

1986-12-01

ridge. Sponge layers protect all boundaries except the eastern one from wave reflexion. The model is forced by a purely fluctuating wind stress curl...which propagate westward. This is a new feature of the time- dependent wind driven ocean circulation. Barnier uses a wind stress curl field patterned...forced by a purely fluctuating wind stress curl derived from the most significant EOF’s of the FGGE winds. A flat bottom and a ridge experiment are

Exploratory Research on Personnel Long Range Planning

DTIC Science & Technology

1982-05-01

rN4 and Joyce ShieldsI AR I ’I.0 04E~i Reserch nsttuteforU. S., Army K-Z Reearh Istiuteforthe Behavioral and Social Sciences May 1982 4S () 9 2~s.? 001...should be included in a personnel long ,ang plan (PLRP), DD , 0711W03 mno EOF@ 9 Nov sois@oneum UNCLASSIFIED SECURITY CLASSIFICATION OF TNIS PAE9 (ftaft...Accessions 3-16 3-7 FY1998 Distribution of Non-Prior-Service Accessions 3-17 3-8 FY1988 Distribution of Non-Prior-Service Accessions 3-18 * 3- 9 FY1989

Multivariate statistical data analysis methods for detecting baroclinic wave interactions in the thermally driven rotating annulus

NASA Astrophysics Data System (ADS)

von Larcher, Thomas; Harlander, Uwe; Alexandrov, Kiril; Wang, Yongtai

2010-05-01

Experiments on baroclinic wave instabilities in a rotating cylindrical gap have been long performed, e.g., to unhide regular waves of different zonal wave number, to better understand the transition to the quasi-chaotic regime, and to reveal the underlying dynamical processes of complex wave flows. We present the application of appropriate multivariate data analysis methods on time series data sets acquired by the use of non-intrusive measurement techniques of a quite different nature. While the high accurate Laser-Doppler-Velocimetry (LDV ) is used for measurements of the radial velocity component at equidistant azimuthal positions, a high sensitive thermographic camera measures the surface temperature field. The measurements are performed at particular parameter points, where our former studies show that kinds of complex wave patterns occur [1, 2]. Obviously, the temperature data set has much more information content as the velocity data set due to the particular measurement techniques. Both sets of time series data are analyzed by using multivariate statistical techniques. While the LDV data sets are studied by applying the Multi-Channel Singular Spectrum Analysis (M - SSA), the temperature data sets are analyzed by applying the Empirical Orthogonal Functions (EOF ). Our goal is (a) to verify the results yielded with the analysis of the velocity data and (b) to compare the data analysis methods. Therefor, the temperature data are processed in a way to become comparable to the LDV data, i.e. reducing the size of the data set in such a manner that the temperature measurements would imaginary be performed at equidistant azimuthal positions only. This approach initially results in a great loss of information. But applying the M - SSA to the reduced temperature data sets enable us to compare the methods. [1] Th. von Larcher and C. Egbers, Experiments on transitions of baroclinic waves in a differentially heated rotating annulus, Nonlinear Processes in Geophysics, 2005, 12, 1033-1041, NPG Print: ISSN 1023-5809, NPG Online: ISSN 1607-7946 [2] U. Harlander, Th. von Larcher, Y. Wang and C. Egbers, PIV- and LDV-measurements of baroclinic wave interactions in a thermally driven rotating annulus, Experiments in Fluids, 2009, DOI: 10.1007/s00348-009-0792-5

Decadal climate variability and the spatial organization of deep hydrological drought

NASA Astrophysics Data System (ADS)

Barros, Ana P.; Hodes, Jared L.; Arulraj, Malarvizhi

2017-10-01

Empirical Orthogonal Function (EOF), wavelet, and wavelet coherence analysis of baseflow time-series from 126 streamgauges (record-length > 50 years; small and mid-size watersheds) in the US South Atlantic (USSA) region reveal three principal modes of space-time variability: (1) a region-wide dominant mode tied to annual precipitation that exhibits non-stationary decadal variability after the mid 1990s concurrent with the warming of the AMO (Atlantic Multidecadal Oscillation); (2) two spatial modes, east and west of the Blue Ridge, exhibiting nonstationary seasonal to sub-decadal variability before and after 1990 attributed to complex nonlinear interactions between ENSO and AMO impacting precipitation and recharge; and (3) deep (decadal) and shallow (< 6 years) space-time modes of groundwater variability separating basins with high and low annual mean baseflow fraction (MBF) by physiographic region. The results explain the propagation of multiscale climate variability into the regional groundwater system through recharge modulated by topography, geomorphology, and geology to determine the spatial organization of baseflow variability at decadal (and longer) time-scales, that is, deep hydrologic drought. Further, these findings suggest potential for long-range predictability of hydrological drought in small and mid-size watersheds, where baseflow is a robust indicator of nonstationary yield capacity of the underlying groundwater basins. Predictive associations between climate mode indices and deep baseflow (e.g. persistent decreases of the decadal-scale components of baseflow during the cold phase of the AMO in the USSA) can be instrumental toward improving forecast lead-times and long-range mitigation of severe drought.

Forced and Internal Multi-Decadal Variability in the North Atlantic and their Climate Impacts

NASA Astrophysics Data System (ADS)

Ting, M.

2017-12-01

Atlantic Multidecadal Variability (AMV), a basin-wide North Atlantic sea surface temperature warming or cooling pattern varying on decadal and longer time scales, is one of the most important climate variations in the Atlantic basin. The AMV has shown to be associated with significant climate impacts regionally and globally, from Atlantic hurricane activities, frequency and severity of droughts across North America, as well as rainfall anomalies across the African Sahel and northeast Brazil. Despite the important impacts of the AMV, its mechanisms are not completely understood. In particular, it is not clear how much of the historical Atlantic SST fluctuations were forced by anthropogenic sources such as greenhouse warming and aerosol cooling, versus driven internally by changes in the coupled ocean-atmosphere processes in the Atlantic. Using climate models such as the NCAR large ensemble simulations, we were able to successfully separate the forced and internally generated North Atlantic sea surface temperature anomalies through a signal-to-noise maximizing Empirical Orthogonal Function (S/N EOF) analysis method. Two forced modes were identified with one representing a hemispherical symmetric mode and one asymmetric mode. The symmetric mode largely represents the greenhouse forced component while the asymmetric mode resembles the anthropogenic aerosol forcing. When statistically removing both of the forced modes, the residual multidecadal Atlantic SST variability shows a very similar structure as the AMV in the preindustrial simulation. The distinct climate impacts of each of these modes are also identified and the implications and challenges for decadal climate prediction will be discussed.

Surface Charge, Electroosmotic Flow and DNA Extension in Chemically Modified Thermoplastic Nanoslits and Nanochannels

PubMed Central

Uba, Franklin I.; Pullagurla, Swathi R.; Sirasunthorn, Nichanun; Wu, Jiahao; Park, Sunggook; Chantiwas, Rattikan; Cho, Yoonkyoung; Shin, Heungjoo; Soper, Steven A.

2014-01-01

Thermoplastics have become attractive alternatives to glass/quartz for microfluidics, but the realization of thermoplastic nanofluidic devices has been slow in spite of the rather simple fabrication techniques that can be used to produce these devices. This slow transition has in part been attributed to insufficient understanding of surface charge effects on the transport properties of single molecules through thermoplastic nanochannels. We report the surface modification of thermoplastic nanochannels and an assessment of the associated surface charge density, zeta potential and electroosmotic flow (EOF). Mixed-scale fluidic networks were fabricated in poly(methylmethacrylate), PMMA. Oxygen plasma was used to generate surface-confined carboxylic acids with devices assembled using low temperature fusion bonding. Amination of the carboxylated surfaces using ethylenediamine (EDA) was accomplished via EDC coupling. XPS and ATR-FTIR revealed the presence of carboxyl and amine groups on the appropriately prepared surfaces. A modified conductance equation for nanochannels was developed to determine their surface conductance and was found to be in good agreement with our experimental results. The measured surface charge density and zeta potential of these devices were lower than glass nanofluidic devices and dependent on the surface modification adopted, as well as the size of the channel. This property, coupled to an apparent increase in fluid viscosity due to nanoconfinement, contributed to the suppression of the EOF in PMMA nanofluidic devices by an order of magnitude compared to the micro-scale devices. Carboxylated PMMA nanochannels were efficient for the transport and elongation of λ-DNA while these same DNA molecules were unable to translocate through aminated nanochannels. PMID:25369728

Surface charge, electroosmotic flow and DNA extension in chemically modified thermoplastic nanoslits and nanochannels.

PubMed

Uba, Franklin I; Pullagurla, Swathi R; Sirasunthorn, Nichanun; Wu, Jiahao; Park, Sunggook; Chantiwas, Rattikan; Cho, Yoon-Kyoung; Shin, Heungjoo; Soper, Steven A

2015-01-07

Thermoplastics have become attractive alternatives to glass/quartz for microfluidics, but the realization of thermoplastic nanofluidic devices has been slow in spite of the rather simple fabrication techniques that can be used to produce these devices. This slow transition has in part been attributed to insufficient understanding of surface charge effects on the transport properties of single molecules through thermoplastic nanochannels. We report the surface modification of thermoplastic nanochannels and an assessment of the associated surface charge density, zeta potential and electroosmotic flow (EOF). Mixed-scale fluidic networks were fabricated in poly(methylmethacrylate), PMMA. Oxygen plasma was used to generate surface-confined carboxylic acids with devices assembled using low temperature fusion bonding. Amination of the carboxylated surfaces using ethylenediamine (EDA) was accomplished via EDC coupling. XPS and ATR-FTIR revealed the presence of carboxyl and amine groups on the appropriately prepared surfaces. A modified conductance equation for nanochannels was developed to determine their surface conductance and was found to be in good agreement with our experimental results. The measured surface charge density and zeta potential of these devices were lower than glass nanofluidic devices and dependent on the surface modification adopted, as well as the size of the channel. This property, coupled to an apparent increase in fluid viscosity due to nanoconfinement, contributed to the suppression of the EOF in PMMA nanofluidic devices by an order of magnitude compared to the micro-scale devices. Carboxylated PMMA nanochannels were efficient for the transport and elongation of λ-DNA while these same DNA molecules were unable to translocate through aminated nanochannels.

Remote sensing evaluation of CLM4 GPP for the period 2000 to 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Jiafu; Thornton, Peter E; Shi, Xiaoying

2012-01-01

The ability of a process-based ecosystem model like Version 4 of the Community Land Model (CLM4) to provide accurate estimates of CO2 flux is a top priority for researchers, modelers and policy makers. Remote sensing can provide long-term and large scale products suitable for ecosystem model evaluation. Global estimations of gross primary production (GPP) at the 1 km spatial resolution from years 2000 to 2009 from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor offer a unique opportunity for evaluating the temporal and spatial patterns of global GPP and its relationship with climate for CLM4. We compare monthly GPP simulated bymore » CLM4 at half-degree resolution with satellite estimates of GPP from the MODIS GPP (MOD17) dataset for the 10-yr period, January 2000 December 2009. The assessment is presented in terms of long-term mean carbon assimilation, seasonal mean distributions, amplitude and phase of the annual cycle, and intra-annual and inter-annual GPP variability and their responses to climate variables. For the long-term annual and seasonal means, major GPP patterns are clearly demonstrated by both products. Compared to the MODIS product, CLM4 overestimates the magnitude of GPP for tropical evergreen forests. CLM4 has longer carbon uptake period than MODIS for most plant functional types (PFTs) with an earlier onset of GPP in spring and later decline of GPP in autumn. Empirical Orthogonal Function (EOF) analysis of the monthly GPP changes indicates that on the intra-annual scale, both CLM4 and MODIS display similar spatial representations and temporal patterns for most terrestrial ecosystems except in northeast Russia and the very dry region in central Australia. For 2000-2009, CLM4 simulates increases in annual averaged GPP over both hemispheres, however estimates from MODIS suggest a reduction in the Southern Hemisphere (-0.2173 PgC/year) balancing the significant increase over the Northern Hemisphere (0.2157 PgC/year).« less

A better GRACE solution for improving the regional Greenland mass balance

NASA Astrophysics Data System (ADS)

Schrama, E.; Xu, Z.

2012-04-01

In most GRACE based researches, a variety of smoothing methods is employed to remove alternating bands of positive and negative stripes stretching in the north-south direction. Many studies have suggested to smooth the GRACE maps, on which mass variations are represented as equivalent water height (EWH). Such maps are capable of exposing the redistribution of earth surface mass over time. In Greenland the shrinking of the ice cap becomes significant in the last decade. Our present study confirms that the dominating melting trends are in the east and southeast coastal zones, however, the smoothed signals along the coastline in these areas do not represent the original but averaged measurements from GRACE satellites which means the signal strength indicating that negative mass variations are mixed with some positive signals that are very close to this area. An exact identification of the topographic edge is not possible and visually the EWH maps appear to be blurred. To improve this, we firstly used spherical harmonic coefficients of GRACE level-2 data from CSR-RL04 and produced a smoothed EWH map. Empirical Orthogonal Functions(EOF)/Principal Component Analysis(PCA) have been introduced as well, in order to extract the melting information associated with the recent warming climate. Next, the Greenland area is redefined by 16 basins and the corresponding melting zones are quantified respectively. Least Squares methods are invoked to interpolate the mass distribution function on each basin. In this way we are able to estimate more accurately regional ice melting rate and we sharpen the EWH map. After comparing our results with a hydrological model the combination SMB - D is established which contains the surface mass balance (SMB) and ice-discharge (D). A general agreement can be reached and it turns out this method is capable to enhance our understanding of the shrinking global cryosphere

Archiving and Exchange of a Computerized Marine Seismic Database: The ROSE (Rivera Ocean Seismic Experiment) Data Archive System

DTIC Science & Technology

1983-12-01

END IF 322 : C WRITE VAHIABLES, mCLDDING KEYWORDS, TO CATBUF 323: C 324: . CATX Bir70UT(CATLrH,CATBOT,112,rEOF) 325...SCORR.SD.SIZE,RC0RR,RD,RANGE 7012 . FORMAT(6F10.4) 91 92 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338...SIZEMX 320: 2013 FORMATC Max shot size:’,F10.4,’ Enter size:’) 118 321 322 323 14 324 2014 325 326 327 15 328 2015 329 330 331 16

The Effects of Glacial and Oceanic Advection on Spatial Patterns of Freshwater Contents and Temperatures of Small Fjords and Major Basins in Prince William Sound, Alaska

NASA Astrophysics Data System (ADS)

Gay, S. M., III

2016-02-01

Using spatial principal component (PC) analysis, the variation in freshwater contents and temperatures in the upper 100m are quantified for small fjords and primary basins within Prince William Sound, Alaska. Two EOF modes explain over 90% of the variance in the freshwater content anomalies (FWCA) giving the total magnitude and vertical structure of the FWCAs respectively. Large, positive PC amplitudes (PCAs) of modes 1 and 2 indicate stratification from surface freshening, shown also by negative surface salinity anomalies, whereas positive FWCA PCAs in conjunction with negative mode 2 amplitudes infer higher subsurface freshening due to either vertical mixing or advection. In contrast, basins with negative mode 1 amplitudes are typically salty to slightly brackish, but the mode 2 PCAs determine if the FWC is concentrated near the surface or mixed deeper in the water column. The vertical structure of the temperature anomalies (TA) is more complicated, and at least three EOF modes are required to explain over 90% of the variance. The reasons for this include differences in solar heating (i.e. local climates) modulated by cold alpine runoff and advection of cold, brackish surface and subsurface glacial water. Fjords and major basins influenced by the latter exhibit large, positive mode 1 amplitudes of FWCA and negative mode 1 and 2 PCAs of TA and FWCA respectively. In certain fjords, however, advection of glacial water into the outer basins enhances the total FWC, whereas other fjords exhibit atypically low FWC due to unusual topographic features of the watersheds and inner basins. This combination of factors leads to generally poor correlations between average FWC and watershed to fjord surface area ratios or hydrology. With exception of a few sites, gradients in FWC between the small fjords and major basins are relatively weak. Thus the main driver of baroclinic flow in northern and western PWS is cold, brackish surface and subsurface water propagating from large tidewater glacial fjords. The glacial water has a marked affect on the dynamic topography, which shows southerly baroclinic-geostrophic flows within the western sound. At Montague Strait and Hinchinbrook Entrance inflows may occur from either fresh or salty conditions; low water density of the latter being shown by negative (positive) FWCA (TA) PCAs respectively.

Asian Summer Monsoon Rainfall associated with ENSO and its Predictability

NASA Astrophysics Data System (ADS)

Shin, C. S.; Huang, B.; Zhu, J.; Marx, L.; Kinter, J. L.; Shukla, J.

2015-12-01

The leading modes of the Asian summer monsoon (ASM) rainfall variability and their seasonal predictability are investigated using the CFSv2 hindcasts initialized from multiple ocean analyses over the period of 1979-2008 and observation-based analyses. It is shown that the two leading empirical orthogonal function (EOF) modes of the observed ASM rainfall anomalies, which together account for about 34% of total variance, largely correspond to the ASM responses to the ENSO influences during the summers of the developing and decaying years of a Pacific anomalous event, respectively. These two ASM modes are then designated as the contemporary and delayed ENSO responses, respectively. It is demonstrated that the CFSv2 is capable of predicting these two dominant ASM modes up to the lead of 5 months. More importantly, the predictability of the ASM rainfall are much higher with respect to the delayed ENSO mode than the contemporary one, with the predicted principal component time series of the former maintaining high correlation skill and small ensemble spread with all lead months whereas the latter shows significant degradation in both measures with lead-time. A composite analysis for the ASM rainfall anomalies of all warm ENSO events in this period substantiates the finding that the ASM is more predictable following an ENSO event. The enhanced predictability mainly comes from the evolution of the warm SST anomalies over the Indian Ocean in the spring of the ENSO maturing phases and the persistence of the anomalous high sea surface pressure over the western Pacific in the subsequent summer, which the hindcasts are able to capture reasonably well. The results also show that the ensemble initialization with multiple ocean analyses improves the CFSv2's prediction skill of both ENSO and ASM rainfall. In fact, the skills of the ensemble mean hindcasts initialized from the four different ocean analyses are always equivalent to the best ones initialized from any individual ocean analysis, although the best performer varies with lead-time and starting calendar month.

Role of climate anomalies on decadal variation in the occurrence of wintertime haze in the Yangtze River Delta, China.

PubMed

Xu, Jianming; Chang, Luyu; Yan, Fengxia; He, JinHai

2017-12-01

The wintertime haze day (HD) in the Yangtze River Delta (YRD) region of China shows a significant upward trend during the past decades due to the rapid industrialization and urbanization. Besides the enhanced anthropogenic emission, climate change also plays the important role in the long term HD variations. In this study, the significant decadal variation of wintertime HD during the period 1960-2012 in YRD is examined by the empirical orthogonal function (EOF) analysis, featured as less HD occurrence before 1980 and more occurrence after 2000. The numerical simulations by the global transport and chemical model (Model for Ozone and Related chemical Tracers, MOZART) with the same emission inventory suggest 8.4% enhancement of wintertime PM 2.5 (particulate matter with the equivalent diameter of air dynamics less than or equal to 2.5μm) mass concentration in YRD during 2001-2009 compared with that during 1971-1979 attributed to meteorological changes, indicating the significant effect of climate anomaly on the decadal variations of wintertime HD. Through the composite analysis on the atmospheric dynamical and thermal conditions based on the reanalysis data, the faster warming in the lower and middle troposphere over the continent in the recent decade is suggested to be important for the out-of-phase decadal HD variation in YRD. The thermal anomaly not only reverses the zonal thermal difference of land-sea to stimulate the anomalous southerlies over YRD leading to reduced prevailing north wind in winter, but also develops the deep inversion below the mid-troposphere to enhance the atmospheric stability. As a result, more frequent and persistent air stagnations in recent decade are expected for the reduction of atmospheric horizontal dispersion and vertical diffusion capacity leading to more occurrence of wintertime HD in YRD. Copyright © 2017 Elsevier B.V. All rights reserved.

Improving visibility of rear surface cracks during inductive thermography of metal plates using Autoencoder

NASA Astrophysics Data System (ADS)

Xie, Jing; Xu, Changhang; Chen, Guoming; Huang, Weiping

2018-06-01

Inductive thermography is one kind of infrared thermography (IRT) technique, which is effective in detection of front surface cracks in metal plates. However, rear surface cracks are usually missed due to their weak indications during inductive thermography. Here we propose a novel approach (AET: AE Thermography) to improve the visibility of rear surface cracks during inductive thermography by employing the Autoencoder (AE) algorithm, which is an important block to construct deep learning architectures. We construct an integrated framework for processing the raw inspection data of inductive thermography using the AE algorithm. Through this framework, underlying features of rear surface cracks are efficiently extracted and new clearer images are constructed. Experiments of inductive thermography were conducted on steel specimens to verify the efficacy of the proposed approach. We visually compare the raw thermograms, the empirical orthogonal functions (EOFs) of the prominent component thermography (PCT) technique and the results of AET. We further quantitatively evaluated AET by calculating crack contrast and signal-to-noise ratio (SNR). The results demonstrate that the proposed AET approach can remarkably improve the visibility of rear surface cracks and then improve the capability of inductive thermography in detecting rear surface cracks in metal plates.

Variability of sea surface height and circulation in the North Atlantic: Forcing mechanisms and linkages

NASA Astrophysics Data System (ADS)

Wang, Zeliang; Lu, Youyu; Dupont, Frederic; W. Loder, John; Hannah, Charles; G. Wright, Daniel

2015-03-01

Simulations with a coarse-resolution global ocean model during 1958-2004 are analyzed to understand the inter-annual and decadal variability of the North Atlantic. Analyses of Empirical Orthogonal Functions (EOFs) suggest relationships among basin-scale variations of sea surface height (SSH) and depth-integrated circulation, and the winter North Atlantic Oscillation (NAO) or the East Atlantic Pattern (EAP) indices. The linkages between the atmospheric indices and ocean variables are shown to be related to the different roles played by surface momentum and heat fluxes in driving ocean variability. In the subpolar region, variations of the gyre strength, SSH in the central Labrador Sea and the NAO index are highly correlated. Surface heat flux is important in driving variations of SSH and circulation in the upper ocean and decadal variations of the Atlantic Meridional Overturning Circulation (AMOC). Surface momentum flux drives a significant barotropic component of flow and makes a noticeable contribution to the AMOC. In the subtropical region, momentum flux plays a dominant role in driving variations of the gyre circulation and AMOC; there is a strong correlation between gyre strength and SSH at Bermuda.

The Onset of the Madden-Julian Oscillation Within an Aquaplanet Model

NASA Technical Reports Server (NTRS)

Colon, Edward; Lindesay, James; Suarez, Max

1997-01-01

A series of numerical experiments using a two-level atmospheric general circulation model (AGCM) were performed for the purpose of investigating the coupling between sea surface temperature (SST) profile and the onset of the Madden-Julian Oscillation (MJO). The AGCM was modified to run as an aquaplane with all seasonal forcing removed. SST distributions based on the New Global Sea-Ice and Sea Surface Temperature (GISST) Data Set for 1903-1994 were generated then modified to vary the north-south gradient and tropical temperatures. It was found that the MJO signal did not depend on the SST temperature gradients but rather on the absolute temperature of the equatorial region, EOF analysis revealed that the SST distribution which generated the strongest MJO signal produced a periodic fluctuation in velocity potential at the 250 millibar level with a phase speed of 15 m/s, and a periodicity of 30 days which falls within the shortest limit of observed oscillations. This distribution also possessed the coolest equatorial SSTs which suggests that increased stability in the atmosphere favors the occurrence of organized MJO propagation.

Subsampled Numerical Experiments as a Guide for Field Deployment of Thermistor Chains

NASA Astrophysics Data System (ADS)

Shaw, Justin; Stastna, Marek

2017-11-01

Thermistor chains are a standard tool for recording temperature profiles in geophysical flows. Density values can be inferred from readings and the resulting density field analyzed for the passage of internal waves, Kelvin-Helmholtz billows, and other dynamic events. The number and spacing of the thermistors, both on and between chains, determines which events can be identified in the dataset. We examine the effect of changing these variables by subsampling a set of numerical experiments to simulate thermistor chain locations. A pseudo spectral method was used to solve the incompressible Navier-Stokes equations under the Boussinesq approximation. The resulting flows are a set of high resolution seiches where the depth was held constant across experiments, and the length was varied. Sampling a known, commonly occurring flow with relatively simple geometry allows for a clear analysis of the effects of thermistor placement in the capture of dynamic events. We will discuss three dimensional deployment strategies, as well as EOF and DMD analyses if there is time. Funded by a Grant from the National Sciences and Engineering Research Council of Canada.

Rapid sample screening method for authenticity controlling vanilla flavors using a CE microchip approach with electrochemical detection.

PubMed

Avila, Mónica; González, María Cristina; Zougagh, Mohammed; Escarpa, Alberto; Ríos, Angel

2007-11-01

Five vanilla-related flavors of food significance, vanillic alcohol (VOH), ethyl maltol (EMA), maltol (MAL), ethyl vanillin (EVA) and vanillin (VAN), were separated using CE microchips with electrochemical detection (CE-ED microchips). A +2 kV driving voltage for both injection and separation operation steps, using a borate buffer (pH 9.5, 20 mM) and 1 M nitric acid in the detection reservoir allowed the selective and sensitive detection of the target analytes in less than 200 s with reproducible control of EOF (RSD(migration times)<3%). The analysis in selected real vanilla samples was focusing on VAN and EVA because VAN is a basic fragrance compound of the vanilla aroma, whereas EVA is an unequivocal proof of adulteration of vanilla flavors. Fast detection of all relevant flavors (200 s) with an acceptable resolution (R(s) >1.5) and a high accuracy (recoveries higher than 90%) were obtained with independence of the matrices and samples examined. These results showed the reliability of the method and the potential use of CE microchips in the food control field for fraudulent purposes.

[Variability of vegetation growth season in different latitudinal zones of North China: a monitoring by NOAA NDVI and MSAVI].

PubMed

Wang, Hong; Li, Xiaobing; Han, Ruibo; Ge, Yongqin

2006-12-01

In this study, North China was latitudinally divided into five zones, i.e., 32 degrees - 36 degrees N (Zone I), 36 degrees - 40 degrees N (Zone II), 40 degrees - 44 degrees N (Zone III), 44 degrees - 48 degrees N (Zone IV) and 48 degrees - 52 degrees N (Zone V), and the NOAA/ AVHRR NDVI and MSAVI time-series images from 1982 to 1999 were smoothed with Savitzky-Golay filter algorithm. Based on the EOF analysis, the principal components of NDVI and MSAVI for the vegetations in different latitudinal zones of North China were extracted, the annual beginning and ending dates and the length of growth season in 1982 - 1999 were estimated, and the related parameters were linearly fitted, aimed to analyze the variability of vegetation growth season. The results showed that the beginning date of the growth season in different zones tended to be advanced, while the ending date tended to be postponed with increasing latitude. The length of the growth season was also prolonged, with the prolonging time exceeded 10 days.

Dynamic microparticle manipulation with an electroosmotic flow gradient in low-frequency alternating current dielectrophoresis.

PubMed

Gencoglu, Aytug; Olney, David; LaLonde, Alexandra; Koppula, Karuna S; Lapizco-Encinas, Blanca H

2014-02-01

In this study, the potential of low-frequency AC insulator-based DEP (iDEP) was explored for the separation of polystyrene microparticles and yeast cells. An EOF gradient was generated by employing an asymmetrical, 20 Hz AC electrical signal in an iDEP device consisting of a microchannel with diamond-shaped insulating posts. Two types of samples were analyzed, the first sample contained three types of polystyrene particles with different diameters (0.5, 1.0, and 2.0 μm) and the second sample contained two types of polystyrene particles (1.0 and 2 μm) and yeast cells (6.3 μm). This particular scheme uses a tapered AC signal that allows for all particles to be trapped and concentrated at the insulating post array, as the signal becomes asymmetrical (more positive), particles are selectively released. The smallest particles in each sample were released first, since they require greater dielectrophoretic forces to remain trapped. The largest particles in each sample were released last, when the applied signal became cyclical. A dielectropherogram, which is analogous to a chromatogram, was obtained for each sample, demonstrating successful separation of the particles by showing "peaks" of the released particles. These separations were achieved at lower applied potentials than those reported in previous studies that used solely direct current electrical voltages. Additionally, mathematical modeling with COMSOL Multiphysics was carried out to estimate the magnitude of the dielectrophoretic and EOF forces acting on the particles considering the low-frequency, asymmetrical AC signal used in the experiments. The results demonstrated the potential of low-frequency AC-iDEP systems for handling and separating complex mixtures of microparticles and biological cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A hydrophobic ionic liquid compartmentalized sampling/labeling and its separation techniques in polydimethylsiloxane microchip capillary electrophoresis.

PubMed

Quan, Hong Hua; Li, Ming; Huang, Yan; Hahn, Jong Hoon

2017-01-01

This paper demonstrates a novel compartmentalized sampling/labeling method and its separation techniques using a hydrophobic ionic liquid (IL)-1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imidate (BmimNTf 2 )-as the immiscible phase, which is capable of minimizing signal losses during microchip capillary electrophoresis (MCE). The MCE device consists of a silica tube connected to a straight polydimethylsiloxane (PDMS) separation channel. Poly(diallyldimethylammonium chloride) (PDDAC) was coated on the inner surface of channel to ease the introduction of IL plugs and enhance the IL wetting on the PDMS surface for sample releasing. Electroosmotic flow (EOF)-based sample compartmentalization was carried out through a sequenced injection into sampling tubes with the following order: leading IL plug/sample segment/terminal IL plug. The movement of the sample segment was easily controlled by applying an electrical voltage across both ends of the chip without a sample volume change. This approach effectively prevented analyte diffusion before injection into MCE channels. When the sample segment was manipulated to the PDDAC-modified PDMS channel, the sample plug then was released from isolation under EOF while IL plugs adsorbed onto channel surfaces owing to strong adhesion. A mixture of flavin adenine nucleotides (FAD) and flavin mononucleotides (FMN) was successfully separated on a 2.5 cm long separation channel, for which the theoretical numbers of plates were 15 000 and 17 000, respectively. The obtained peak intensity was increased 6.3-fold over the corresponding value from conventional electrokinetic injection with the same sampling time. Furthermore, based on the compartmented sample segment serving as an interim reactor, an on-chip fluorescence labeling is demonstrated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proline-coated column for the capillary electrochromatographic separation of amino acids by in-column derivatization.

PubMed

Lin, Chun-Chi; Liu, Chuen-Ying

2004-10-01

With 3-trimethoxysilylpropyl chloride as the spacer, a proline-coated capillary column was prepared for the capillary electrochromatographic (CEC) separation of amino acids by in-column derivatization. Nine standard mixtures, including aspartic acid, glutamic acid, valine, phenylalanine, alanine, isoleucine, leucine, tyrosine, and tryptophan, were injected. o-Phthalaldehyde (OPA), OPA/2-mercaptoethanol (2-ME) and OPA/N-acetylcysteine (NAC) in borate buffer were tested as the derivatizing agent. Among them, OPA (50 mM) in borate buffer (pH 9.5, 50 mM) gave the best performance. The formation of isoindole could be detected by UV detection. The sandwich-type injection was carried out in hydrostatic mode (10 cm) with the program R(10 s)S(10 s) R(10 s)W(10 min) with R, S, and W being the reagent, sample, and waiting times. Mesityl oxide, benzyl alcohol, and acetone showed some interaction with the column. A current monitoring method was used instead of the determination of the electroosmotic flow (EOF). The direction of EOF was from anode to cathode even under acidic condition lower than the pI value (6.31) of the bonded group due to some unreacted silanol groups. Some parameters including pH, nature, and concentration of the mobile phase and the effect of organic modifier with regard to the CEC separation were investigated. With the proline-coated column (75 (50) cm x 75 microm ID) the best separation was performed in phosphate buffer (pH 4.00, 100 mM) with an applied voltage of -15 kV. The established method was also compared with those precolumn derivatized prior to the separation with proline-coated column as well as with in-capillary derivatization and separation with a bare fused-silica column. Copyright 2004 WILEY-VCH Verlag GmbH & Co.

Surface Snow Density of East Antarctica Derived from In-Situ Observations

NASA Astrophysics Data System (ADS)

Tian, Y.; Zhang, S.; Du, W.; Chen, J.; Xie, H.; Tong, X.; Li, R.

2018-04-01

Models based on physical principles or semi-empirical parameterizations have used to compute the firn density, which is essential for the study of surface processes in the Antarctic ice sheet. However, parameterization of surface snow density is often challenged by the description of detailed local characterization. In this study we propose to generate a surface density map for East Antarctica from all the filed observations that are available. Considering that the observations are non-uniformly distributed around East Antarctica, obtained by different methods, and temporally inhomogeneous, the field observations are used to establish an initial density map with a grid size of 30 × 30 km2 in which the observations are averaged at a temporal scale of five years. We then construct an observation matrix with its columns as the map grids and rows as the temporal scale. If a site has an unknown density value for a period, we will set it to 0 in the matrix. In order to construct the main spatial and temple information of surface snow density matrix we adopt Empirical Orthogonal Function (EOF) method to decompose the observation matrix and only take first several lower-order modes, because these modes already contain most information of the observation matrix. However, there are a lot of zeros in the matrix and we solve it by using matrix completion algorithm, and then we derive the time series of surface snow density at each observation site. Finally, we can obtain the surface snow density by multiplying the modes interpolated by kriging with the corresponding amplitude of the modes. Comparative analysis have done between our surface snow density map and model results. The above details will be introduced in the paper.

Time Changes of the European Gravity Field from GRACE: A Comparison with Ground Measurements from Superconducting Gravimeters and with Hydrology Model Predictions

NASA Technical Reports Server (NTRS)

Hinderer, J.; Lemoine, Frank G.; Crossley, D.; Boy, J.-P.

2004-01-01

We investigate the time-variable gravity changes in Europe retrieved from the initial GRACE monthly solutions spanning a 18 month duration from April 2002 to October 2003. Gravity anomaly maps are retrieved in Central Europe from the monthly satellite solutions we compare the fields according to various truncation levels (typically between degree 10 and 20) of the initial fields (expressed in spherical harmonics to degree 120). For these different degrees, an empirical orthogonal function (EOF) decomposition of the time-variable gravity field leads us to its main spatial and temporal characteristics. We show that the dominant signal is found to be annual with an amplitude and a phase both in agreement with predictions in Europe modeled using snow and soil-moisture variations from recent hydrology models. We compare these GRACE gravity field changes to surface gravity observations from 6 superconducting gravimeters of the GGP (Global Geodynamics Project) European sub-network, with a special attention to loading corrections. Initial results suggest that all 3 data sets (GRACE, hydrology and GGP) are responding to annual changes in near-surface water in Europe of a few microGal (at length scales of approx.1000 km) that show a high value in winter and a summer minimum. We also point out that the GRACE gravity field evolution seems to indicate that there is a trend in gravity between summer 2002 and summer 2003 which can be related to the 2003 heatwave in Europe and its hydrological consequences (drought). Despite the limited time span of our analysis and the uncertainties in retrieving a regional solution from the network of gravimeters, the calibration and validation aspects of the GRACE data processing based on the annual hydrology cycle in Europe are in progress.

Teleconnections in the Presence of Climate Change: A Case Study of the Annular Modes

NASA Astrophysics Data System (ADS)

Gerber, Edwin; Baldwin, Mark

2010-05-01

Long model integrations of future and past climates present a problem for defining teleconnection patterns through Empirical Orthogonal Function (EOF) or correlation analysis when trends in the underlying climate begin to dominate the covariance structure. Similar issues may soon appear in observations as the record becomes longer, especially if climate trends accelerate. The Northern and Southern Annular Modes provide a prime example, because the poleward shift of the jet streams strongly projects onto these patterns, particularly in the Southern Hemisphere. Climate forecasts of the 21st century by chemistry climate models provide a case study. Computation of the annular modes in these long data sets with secular trends requires refinement of the standard definition of the annular mode, and a more robust procedure that allows for slowly varying trends is established and verified. The new procedure involves two key changes. First, the global mean geopotential height is removed at each time step before computing anomalies. This is particularly important high in the atmosphere, where seasonal variations in geopotential height become significant, and filters out trends due to changes in the temperature structure of the atmosphere. Pattern definition can be very sensitive near the tropopause, as regions of the atmosphere that used to be more of stratospheric character begin to take on tropospheric characteristics as the tropopause rises. The second change is to define anomalies relative to a slowly evolving seasonal climatology, so that the covariance structure reflects internal variability. Once these changes are accounted for, it is found that the zonal mean variability of the atmosphere stays remarkably constant, despite significant changes in the baseline climate forecast for the rest of the century. This stability of the internal variability makes it possible to relate trends in climate to teleconnections.

Zonal migration and transport variations of the Kuroshio east of Taiwan induced by eddy impingements

NASA Astrophysics Data System (ADS)

Chang, Ming-Huei; Jan, Sen; Mensah, Vigan; Andres, Magdalena; Rainville, Luc; Yang, Yiing Jang; Cheng, Yu-Hsin

2018-01-01

Variability of the Kuroshio east of Taiwan was observed at a cross-stream transect 50 km south of the PCM-1 line with an array of three moored ADCPs measuring for 23 months, supplemented with eleven repeated shipboard surveys. Observations of the Kuroshio's velocity structure reveal the absence of an obvious regular seasonal signal, but significant variability at 70-200 day period for both maximum velocity axis migration and transport due to interactions with mesoscale eddies. Empirical orthogonal function (EOF) analysis shows the migration and transport modes explain 46% and 29% of the total variance, respectively, which is in contrast to the findings at the PCM-1 line where the transport mode explained more variance than did the migration mode. The Kuroshio transport in the upper 500 m across a 150 km section is 17.2 Sv with a standard deviation of 5 Sv. The estimated Kuroshio transport is 4.3 Sv lower than that reported for the PCM-1 line, likely due to the interannual variations related to abundance of mesoscale eddies in the Subtropical Counter Current (STCC) region. Transport variability east of Taiwan is mostly caused by Kuroshio-eddy interactions. When single anticyclonic (cyclonic) eddies encounter the Kuroshio, they enhance (reduce) poleward transport, presumably by increasing (decreasing) the sea level anomaly (SLA) along the eastern flank of the Kuroshio (correlation = 0.82). When a pair of eddies impinges on the Kuroshio, the upstream confluence and diffluence caused by the dipole eddies increases and decreases the Kuroshio transport, respectively. Furthermore, the eastward (westward) currents that result from either the single eddy or the dipole eddy produce flow divergence (convergence) adjacent to the Kuroshio's eastern edge, favoring the offshore (onshore) migration of the Kuroshio axis.

Morphological evolution of Jinshan Trough in Hangzhou Bay (China) from 1960 to 2011

NASA Astrophysics Data System (ADS)

Liu, Yifei; Xia, Xiaoming; Chen, Shenliang; Jia, Jianjun; Cai, Tinglu

2017-11-01

An extensive system of tidal channels, starting with Jinshan Trough in the east, is located along the north shore of Hangzhou Bay, China. This contribution investigates the morphological evolution of Jinshan Trough by using 17 bathymetric charts from a series covering a period of 51 years from 1960 to 2011. Three stages of evolution during this period are distinguishable based on the morphology and annual mean volume data. The first stage (1960-1987) is characterized by extension of the trough; the second stage (1987-1996) is a relatively stable period with some adjustments in the trough morphology; the third stage (1996-2011) is marked by the processes of erosion and deposition in the beginning of the period and a subsequent slow erosion process. Spatio-temporal variability of the trough was evaluated by using empirical orthogonal function (EOF) analysis. The first eigenfunction indicates that erosion is the main evolution process and there exists three stages similar to those distinguished from volume variations. The second eigenfunction mainly reflects erosion and deposition in the northwest part of the trough located in the flood tidal current shadow area of the artificial headland in Jinshan. The third eigenfunction mainly reflects annual fluctuations of erosion and deposition in the side slope at the artificial headland in Jinshan. A particularly intense erosion process occurred between 1996 and 1998. The major effects on morphological evolution in Jinshan Trough from 1960 to 2011 were investigated and tentative conclusions were presented. Continuous coastal reclamations in Jinshan had the most pronounced effect on the morphological evolution during the first and the second stages. The storm surge had a pronounced effect on the evolution at the beginning of the third stage.

Multi-scale linkages of winter drought variability to ENSO and the Arctic Oscillation: A case study in Shaanxi, North China

NASA Astrophysics Data System (ADS)

Liu, Zhiyong; Zhang, Xin; Fang, Ruihong

2018-02-01

Understanding the potential connections between climate indices such as the El Niño-Southern Oscillation (ENSO) and Arctic Oscillation (AO) and drought variability will be beneficial for making reasonable predictions or assumptions about future regional droughts, and provide valuable information to improve water resources planning and design for specific regions of interest. This study is to examine the multi-scale relationships between winter drought variability over Shaanxi (North China) and both ENSO and AO during the period 1960-2009. To accomplish this, we first estimated winter dryness/wetness conditions over Shaanxi based on the self-calibrating Palmer drought severity index (PDSI). Then, we identified the spatiotemporal variability of winter dryness/wetness conditions in the study area by using the empirical orthogonal function (EOF). Two primary sub-regions of winter dryness/wetness conditions across Shaanxi were identified. We further examined the periodical oscillations of dryness/wetness conditions and the multi-scale relationships between dryness/wetness conditions and both ENSO and AO in winter using wavelet analysis. The results indicate that there are inverse multi-scale relations between winter dryness/wetness conditions and ENSO (according to the wavelet coherence) for most of the study area. Moreover, positive multi-scale relations between winter dryness/wetness conditions and AO are mainly observed. The results could be beneficial for making reasonable predictions or assumptions about future regional droughts and provide valuable information to improve water resources planning and design within this study area. In addition to the current study area, this study may also offer a useful reference for other regions worldwide with similar climate conditions.

Easy-to-fabricate thin-film coating on PDMS substrate with super hydrophilicity and stability.

PubMed

Sun, Lijun; Luo, Yong; Gao, Zhigang; Zhao, Weijie; Lin, Bingcheng

2015-03-01

With the fast expansion of microfluidic applications, stable, and easy-to-fabricate PDMS surface coating with super hydrophilicity is highly desirable. In this study, we introduce a new kind of copolymer-based, single-layer thin-film coating for PDMS. The coating can exist in air at room temperature for at least 6 months without any noticeable deterioration in the super hydrophilicity (water contact angle ∼7°), resistance of protein adsorption, or inhibition of the EOF. In addition, this coating enables arbitrary patterning of cells on planar surfaces. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward microscale flow control using non-uniform electro-osmotic flow

NASA Astrophysics Data System (ADS)

Paratore, Federico; Boyko, Evgeniy; Gat, Amir D.; Kaigala, Govind V.; Bercovici, Moran

2018-02-01

We present a novel method that allows establishing desired flow patterns in a Hele-Shaw cell, solely by controlling the surface chemistry, without the use of physical walls. Using weak electrolytes, we locally pattern the chamber's ceiling and/or floor, thus defining a spatial distribution of surface charge. This translates to a non-uniform electric double layer which when subjected to an external electric field applied along the chamber, gives rise to non-uniform electroosmotic flow (EOF). We present the theory that allows prediction and design of such flows fields, as well as experimental demonstrations opening the door to configurable microfluidic devices.

Dual-opposite injection capillary electrophoresis: Principles and misconceptions.

PubMed

Blackney, Donna M; Foley, Joe P

2017-03-01

Dual-opposite injection capillary electrophoresis (DOI-CE) is a separation technique that utilizes both ends of the capillary for sample introduction. The electroosmotic flow (EOF) is suppressed to allow all ions to reach the detector quickly. Depending on the individual electrophoretic mobilities of the analytes of interest and the effective length that each analyte travels to the detection window, the elution order of analytes in a DOI-CE separation can vary widely. This review discusses the principles, applications, and limitations of dual-opposite injection capillary electrophoresis. Common misconceptions regarding DOI-CE are clarified. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spatial-temporal analysis of climate variations in mid-17th through 19th centuries in East China and the possible relationships with Monsoon climate

NASA Astrophysics Data System (ADS)

Lin, K. H. E.; Wang, P. K.; Liao, Y. C.; Lee, S. Y.; Tan, P.

2016-12-01

IPCC AR5 has revealed more frequent extreme climate events and higher climate variability in the near future. Regardless of all the improvements, East Asia monsoon climate is still less understood and/or poorly projected due partly to insufficient records. Most areas of the Asian region lack sufficient observational records to draw conclusions about trends in annual precipitation over the past century (i.e. WGIAR5 Chapter 2). Precipitation trends, including extremes, are characterized by strong variability, with both increasing and decreasing observed in different parts and seasons of Asia. Understanding the variations of the monsoon climate in historical time may bring significant insights to reveal its spatial and temporal patterns embedded in the atmospheric dynamics at different decadal or centennial scales. This study presents some preliminary research results of high resolution climate reconstruction, in both time and space coverage, in east China, by using RCEC historical climate dataset that is developed under interdisciplinary collaboration led by Research Center for Environmental Changes at Academia Sinica, Taiwan. The present research results are derived from chronological meteorological records in the RCEC dataset in Qing dynasty labeling mid-17th to 19th centuries. In total, the dataset comprises more than 1,300 cities/counties in China that has had more than sixty thousands meteorological records in the period. The analysis comprises three parts. Firstly, the frequency of extreme temperature, precipitation, drought, and flood in every recorded cities/counties were computed to depicting climate variabilities in northeast, central-east and southeast China. Secondly, the multivariate regression model was conducted to estimate the coefficients among the climatic index (temperature, precipitation, and drought). It is found that the temperature and wet-dry characteristics have great seasonal and yearly variations; northeast China compared with central-east or southeast tends to have higher variability. Thirdly, those data was used to conduct empirical orthogonal function (EOF) analysis to decompose possible mechanisms that might have cause changes in East Asia monsoon regime during the time period. The reconstructed data were also compared against paleoclimate simulation.

On the application of the Principal Component Analysis for an efficient climate downscaling of surface wind fields

NASA Astrophysics Data System (ADS)

Chavez, Roberto; Lozano, Sergio; Correia, Pedro; Sanz-Rodrigo, Javier; Probst, Oliver

2013-04-01

With the purpose of efficiently and reliably generating long-term wind resource maps for the wind energy industry, the application and verification of a statistical methodology for the climate downscaling of wind fields at surface level is presented in this work. This procedure is based on the combination of the Monte Carlo and the Principal Component Analysis (PCA) statistical methods. Firstly the Monte Carlo method is used to create a huge number of daily-based annual time series, so called climate representative years, by the stratified sampling of a 33-year-long time series corresponding to the available period of the NCAR/NCEP global reanalysis data set (R-2). Secondly the representative years are evaluated such that the best set is chosen according to its capability to recreate the Sea Level Pressure (SLP) temporal and spatial fields from the R-2 data set. The measure of this correspondence is based on the Euclidean distance between the Empirical Orthogonal Functions (EOF) spaces generated by the PCA (Principal Component Analysis) decomposition of the SLP fields from both the long-term and the representative year data sets. The methodology was verified by comparing the selected 365-days period against a 9-year period of wind fields generated by dynamical downscaling the Global Forecast System data with the mesoscale model SKIRON for the Iberian Peninsula. These results showed that, compared to the traditional method of dynamical downscaling any random 365-days period, the error in the average wind velocity by the PCA's representative year was reduced by almost 30%. Moreover the Mean Absolute Errors (MAE) in the monthly and daily wind profiles were also reduced by almost 25% along all SKIRON grid points. These results showed also that the methodology presented maximum error values in the wind speed mean of 0.8 m/s and maximum MAE in the monthly curves of 0.7 m/s. Besides the bulk numbers, this work shows the spatial distribution of the errors across the Iberian domain and additional wind statistics such as the velocity and directional frequency. Additional repetitions were performed to prove the reliability and robustness of this kind-of statistical-dynamical downscaling method.

Estimation of typhoon rainfall in GaoPing River: A Multivariate Maximum Entropy Method

NASA Astrophysics Data System (ADS)

Pei-Jui, Wu; Hwa-Lung, Yu

2016-04-01

The heavy rainfall from typhoons is the main factor of the natural disaster in Taiwan, which causes the significant loss of human lives and properties. Statistically average 3.5 typhoons invade Taiwan every year, and the serious typhoon, Morakot in 2009, impacted Taiwan in recorded history. Because the duration, path and intensity of typhoon, also affect the temporal and spatial rainfall type in specific region , finding the characteristics of the typhoon rainfall type is advantageous when we try to estimate the quantity of rainfall. This study developed a rainfall prediction model and can be divided three parts. First, using the EEOF(extended empirical orthogonal function) to classify the typhoon events, and decompose the standard rainfall type of all stations of each typhoon event into the EOF and PC(principal component). So we can classify the typhoon events which vary similarly in temporally and spatially as the similar typhoon types. Next, according to the classification above, we construct the PDF(probability density function) in different space and time by means of using the multivariate maximum entropy from the first to forth moment statistically. Therefore, we can get the probability of each stations of each time. Final we use the BME(Bayesian Maximum Entropy method) to construct the typhoon rainfall prediction model , and to estimate the rainfall for the case of GaoPing river which located in south of Taiwan.This study could be useful for typhoon rainfall predictions in future and suitable to government for the typhoon disaster prevention .

First Results from HF (High-Frequency) Oblique Backscatter Soundings to the Northwest of College, Alaska Using a Modified ULCAR Digisonde D-256

DTIC Science & Technology

1989-03-01

the D-256: The D-256 vertical sounder has been described in considerable detail by Bibl et al. (1981), but for the sake of completeness, the essential...in Figure 12. 20 Table 3 Status Table for Current Sounder Modes at Sheep Creek 1 VI Z T H X D 7 1 4 (for actual Doppler values, see Table 5.7 in Bibl ...etal, 1981) Azimuth Sequence Code Table 5.9 I oblique ( Bibl ) N P X S U F L V choes have ’EofN 00 3000 2400 1800 1200 600 X 0 polariza ion and Status

Integration of GRACE and GNET GPS in modeling the deglaciation of Greenland

NASA Astrophysics Data System (ADS)

Knudsen, P.; Madsen, F. B.; Khan, S. A.; Bevis, M. G.; van Dam, T. M.

2017-12-01

The use the monthly gravity fields from the Gravity Recovery and Climate Experiment (GRACE) has become essential when assessing and modeling the mass changes of the ice sheets. The recent degradation of the current mission, however, has hampered the continuous monitoring of ice sheet masses, at least until GRACE Follow-On mission will become operational. Through the recent years it has been demonstrated that mass changes can be observed by GPS receivers mounted on the adjacent bedrock. Especially, the Greenland GPS Network (GNET) has proven that GPS is a valuable technique for detecting mass changes through the Earths elastic response. An integration of GNET with other observations of the Greenland ice sheet, e.g. satellite altimetry and GRACE, has made studies of GIA progressing significantly. In this study, we aim at improving the monitoring of the ice sheet mass by utilizing the redundancy for reducing the influence of errors and to fill in at data voids and, not at least to bridge the gap between GRACE and GRACE FO. Initial analyses are carried out to link GRACE and GNET time series empirically. EOF analyses are carried out to extract the main part of the variability and to isolate errors. Subsequently, empirical covariance functions are derived and used in the integration. Preliminary results are derived and inter-compared.

Climatology and variability of SST frontal activity in Eastern Pacific Ocean over the past decade

NASA Astrophysics Data System (ADS)

Wang, Y.; Yuan, Y.

2016-12-01

Distribution of sea surface temperature (SST) fronts are derived from high-resolution MODIS dataset in Eastern Pacific Ocean from 2003 to 2015. Daily distribution of frontal activities shows detailed feature and movement of front and the discontinuity of the track of front cause by cloud coverage. Monthly frontal probability is calculated to investigate corresponding climatology and variability. Frontal probability is generally higher along the coast and decreasing offshore. The frontal activity could extend few hundreds of kilometers near the major capes and central Pacific Ocean. SST gradient associated with front is changing over different latitude with stronger gradient near the mid-latitude and under major topographic effects near tropics. Corresponding results from empirical orthogonal functions (EOF) shows major variability of SST front is found in mid-latitude and central Pacific Ocean. The temporal variability captures a strong interannual and annual variability in those regions, while Intraannual variability are found more important at small scale near major capes and topographic features. The frontal variability is highly impacted by wind stress, upwelling, air-sea interaction, current, topography, eddy activity, El Nino along with other factors. And front plays an importance role in influencing the distribution of nutrients, the activity of fisheries and the development of ecosystems.

Bio-Optical Data Assimilation With Observational Error Covariance Derived From an Ensemble of Satellite Images

NASA Astrophysics Data System (ADS)

Shulman, Igor; Gould, Richard W.; Frolov, Sergey; McCarthy, Sean; Penta, Brad; Anderson, Stephanie; Sakalaukus, Peter

2018-03-01

An ensemble-based approach to specify observational error covariance in the data assimilation of satellite bio-optical properties is proposed. The observational error covariance is derived from statistical properties of the generated ensemble of satellite MODIS-Aqua chlorophyll (Chl) images. The proposed observational error covariance is used in the Optimal Interpolation scheme for the assimilation of MODIS-Aqua Chl observations. The forecast error covariance is specified in the subspace of the multivariate (bio-optical, physical) empirical orthogonal functions (EOFs) estimated from a month-long model run. The assimilation of surface MODIS-Aqua Chl improved surface and subsurface model Chl predictions. Comparisons with surface and subsurface water samples demonstrate that data assimilation run with the proposed observational error covariance has higher RMSE than the data assimilation run with "optimistic" assumption about observational errors (10% of the ensemble mean), but has smaller or comparable RMSE than data assimilation run with an assumption that observational errors equal to 35% of the ensemble mean (the target error for satellite data product for chlorophyll). Also, with the assimilation of the MODIS-Aqua Chl data, the RMSE between observed and model-predicted fractions of diatoms to the total phytoplankton is reduced by a factor of two in comparison to the nonassimilative run.

Is the Aquarius sea surface salinity variability representative?

NASA Astrophysics Data System (ADS)

Carton, J.; Grodsky, S.

2016-12-01

The leading mode of the Aquarius monthly anomalous sea surface salinity (SSS) is evaluated within the 50S-50N belt, where SSS retrieval accuracy is higher. This mode accounts for about 18% of the variance and resembles a pattern of the ENSO-induced anomalous rainfall. The leading mode of SSS variability deducted from a longer JAMSTEC analysis also accounts for about 17% of the variance and has very similar spatial pattern and almost a perfect correspondence of its temporal principal component to the SOI index. In that sense, the Aquarius SSS variability at low and middle latitudes is representative of SSS variability that may be obtained from longer records. This is explained by the fact that during the Aquarius period (2011-2015), the SOI index changed significantly from La Nina toward El Nino state, thus spanning a significant range of its characteristic variations. Multivariate EOF analysis of anomalous SSS and SST suggests that ENSO-induced shift in the tropical Pacific rainfall produces negatively correlated variability of temperature and salinity, which are expected if the anomalous surface flux (stronger rainfall coincident with less downward radiation) drives the system. But, anomalous SSS and SST are positively correlated in some areas including the northwestern Atlantic shelf (north of the Gulfstream) and the Pacific sector adjusting to the California peninsula. This positive correlation is indicative of an advection driven regime that is analyzed separately.

Atmospheric forcing and Sea Surface Temperature response in the Gulf of Cadiz-Alboran Sea system in a 20 years simulation

NASA Astrophysics Data System (ADS)

Boutov, D.; Peliz, A.

2012-04-01

In the frame of MedEX ("Inter-basin exchange in the changing Mediterranean Sea") Project a 20 years (1989-2008) simulation at 2km resolution covering Gulf of Cadiz and Alboran Sea, forced by 9 km winds (WRF downscaling of ERA-Interim reanalysis), is analyzed and compared with observations. Statistical methods, EOF techniques and two harmonic (including annual and semi-annual frequencies) data fit were performed for the analysis. Modeled SST fields are also compared with long-term (1996-2008) in-situ buoy observations provided by Puertos del Estado (Spain) and satellite derived Pathfinder SST database. Model SSTs generally follow observations data at annual and inter-annual scales with a global error not exceeding 0.17°C (model warmer than SST). No significant warming tendency was observed in both basins during the 20 years and the Interanual variability dominates, with the series showing a cooling period from 1991 to 1993 followed by a warming period started from 1994. In particular we show that SST cooling observed in the early 1990's in the Gulf of Cadiz - Alboran system is associated with the 1991 catastrophic eruption of Pinatubo volcano (Philippines).

Interannual Variations in Synoptic-Scale Disturbances over the Western North Pacific

NASA Astrophysics Data System (ADS)

Zhou, Xingyan; Lu, Riyu; Chen, Guanghua; Wu, Liang

2018-05-01

The present study investigates the interannual variation of June-November synoptic disturbance activity over the western North Pacific (WNP) and its relationship with large-scale circulation for the period 1958-2014. Two leading modes of eddy kinetic energy for the disturbance variability over the WNP are obtained by EOF analysis, characterized by anomalous eddy kinetic energy over the subtropical WNP and around the Philippines, respectively. These modes explain a large portion of the interannual variance of synoptic disturbance activity over the WNP. Both are associated with lower-level cyclonic anomalies, but with different locations: over the subtropical WNP for the first mode and over the South China Sea for the second mode. Considering the impact of ENSO on synoptic disturbance activity over the WNP, we repeat the analyses after removing the effect of ENSO, which is simply defined as the components linearly regressed onto the Niño3.4 index, and find similar results, suggesting that the leading modes and their relationships with large-scale circulation exist without SST effects. Further analyses suggest that the meridional shear of zonal winds caused by cyclonic anomalies is crucial for maintaining the leading modes through barotropic conversion.

Implementation of the DINEOF ArcGIS Toolbox: Case study of reconstruction of Chlorophyll-a missing data over the Mediterranean using MyOcean satellite data products.

NASA Astrophysics Data System (ADS)

Nikolaidis, Andreas; Stylianou, Stavros; Georgiou, Georgios; Hadjimitsis, Diofantos; Akylas, Evangelos

2014-05-01

ArcGIS® is a well known standard on Geographical Information Systems, used over the years for various remote sensing procedures. During the last decade, Rixen (2003) and Azcarate (2011) presented the DINEOF (Data Interpolating Empirical Orthogonal Functions) method, a EOF-based technique to reconstruct missing data in satellite images. The recent results of the DINEOF method in various experimental trials (Wang and Liu, 2013; Nikolaidis et al., 2013;2014) showed that this computationally affordable method leads to effective reconstruction of missing data from geophysical fields, such as chlorophyll-a, sea surface temperatures or salinities and geophysical fields derived from satellite data. Implementing the method in a GIS system will lead to a complete and integrated approach, enhancing its applicability. The inclusion of statistical tools within the GIS, will multiply the effectiveness, providing interoperability with other sources in the same application environment. This may be especially useful in studies where various different kinds of data are of interest. For this purpose, in this study we have implemented a new GIS toolbox that aims at automating the usage of the algorithm, incorporating the DINEOF codes provided by GHER (GeoHydrodynamics and Environment Research Group of University of Liege) into the ArcGIS®. A case-study of filling the chlorophyll-a missing data in the Mediterranean Sea area, for a 18-day period is analyzed, as an example for the effectiveness and simplicity of the toolbox. More specifically, we focus on chlorophyll-a MODIS satellite data collected by CNR-ISAC (Italian National Research Council, Institute of Atmospheric Sciences and Climate), from the respective products of MyOcean2® organization, that provides free online access to Level 3, with 1 km resolution. All the daily products with an initial level of only 27% data coverage were successfully reconstructed over the Mediterranean Sea. [1] Alvera-Azcárate A., Barth A.,Sirjacobs D., Lenartz F., Beckers J.-M.. Data Interpolating Empirical Orthogonal Functions (DINEOF): a tool for geophysical data analyses. Medit. Mar. Sci., 5-11, (2011). [2] Rixen M., Beckers J. M.,, EOF Calculations and Data Filling from Incomplete Oceanographic Datasets. Journal of Atmospheric and Oceanic Technology, Vol. 20(12), pp. 1839-1856, (2003) [3] Nikolaidis A., Georgiou G., Hadjimitsis D. and E. Akylas, Applying a DINEOF algorithm on cloudy sea-surface temperature satellite data over the eastern Mediterranean Sea, Central European Journal of Geosciences 6(1), pp. 1-16, (2014) [4] Nikolaidis A., Georgiou G., Hadjimitsis D. and E. Akylas Applying DINEOF algorithm on cloudy sea-surface temperature satellite data over the eastern Mediterranean Sea, Proc. SPIE 8795, First International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2013), 87950L, 8-10 April 2013, Paphos, Cyprus, 10.1117/12.2029085 [5] Wang Y. and D. Liu (2014), Reconstruction of satellite chlorophyll-a data using a modified DINEOF method: a case study in the Bohai and Yellow seas, China, International Journal of Remote Sensing, Vol. 35(1), 204-217, (2014).

Effects of geometric modulation and surface potential heterogeneity on electrokinetic flow and solute transport in a microchannel

NASA Astrophysics Data System (ADS)

Bera, Subrata; Bhattacharyya, S.

2017-12-01

A numerical investigation is performed on the electroosmotic flow (EOF) in a surface-modulated microchannel to induce enhanced solute mixing. The channel wall is modulated by placing surface-mounted obstacles of trigonometric shape along which the surface potential is considered to be different from the surface potential of the homogeneous part of the wall. The characteristics of the electrokinetic flow are governed by the Laplace equation for the distribution of external electric potential; the Poisson equation for the distribution of induced electric potential; the Nernst-Planck equations for the distribution of ions; and the Navier-Stokes equations for fluid flow simultaneously. These nonlinear coupled set of governing equations are solved numerically by a control volume method over the staggered system. The influence of the geometric modulation of the surface, surface potential heterogeneity and the bulk ionic concentration on the EOF is analyzed. Vortical flow develops near a surface modulation, and it becomes stronger when the surface potential of the modulated region is in opposite sign to the surface potential of the homogeneous part of the channel walls. Vortical flow also depends on the Debye length when the Debye length is in the order of the channel height. Pressure drop along the channel length is higher for a ribbed wall channel compared to the grooved wall case. The pressure drop decreases with the increase in the amplitude for a grooved channel, but increases for a ribbed channel. The mixing index is quantified through the standard deviation of the solute distribution. Our results show that mixing index is higher for the ribbed channel compared to the grooved channel with heterogeneous surface potential. The increase in potential heterogeneity in the modulated region also increases the mixing index in both grooved and ribbed channels. However, the mixing performance, which is the ratio of the mixing index to pressure drop, reduces with the rise in the surface potential heterogeneity.

Effects of geometric modulation and surface potential heterogeneity on electrokinetic flow and solute transport in a microchannel

NASA Astrophysics Data System (ADS)

Bera, Subrata; Bhattacharyya, S.

2018-04-01

A numerical investigation is performed on the electroosmotic flow (EOF) in a surface-modulated microchannel to induce enhanced solute mixing. The channel wall is modulated by placing surface-mounted obstacles of trigonometric shape along which the surface potential is considered to be different from the surface potential of the homogeneous part of the wall. The characteristics of the electrokinetic flow are governed by the Laplace equation for the distribution of external electric potential; the Poisson equation for the distribution of induced electric potential; the Nernst-Planck equations for the distribution of ions; and the Navier-Stokes equations for fluid flow simultaneously. These nonlinear coupled set of governing equations are solved numerically by a control volume method over the staggered system. The influence of the geometric modulation of the surface, surface potential heterogeneity and the bulk ionic concentration on the EOF is analyzed. Vortical flow develops near a surface modulation, and it becomes stronger when the surface potential of the modulated region is in opposite sign to the surface potential of the homogeneous part of the channel walls. Vortical flow also depends on the Debye length when the Debye length is in the order of the channel height. Pressure drop along the channel length is higher for a ribbed wall channel compared to the grooved wall case. The pressure drop decreases with the increase in the amplitude for a grooved channel, but increases for a ribbed channel. The mixing index is quantified through the standard deviation of the solute distribution. Our results show that mixing index is higher for the ribbed channel compared to the grooved channel with heterogeneous surface potential. The increase in potential heterogeneity in the modulated region also increases the mixing index in both grooved and ribbed channels. However, the mixing performance, which is the ratio of the mixing index to pressure drop, reduces with the rise in the surface potential heterogeneity.

Was the Little Ice Age more or less El Niño-like than the Mediaeval Climate Anomaly? Evidence from hydrological and temperature proxy data

NASA Astrophysics Data System (ADS)

Henke, L. M. K.; Lambert, F. H.; Charman, D. J.

2015-11-01

The El Niño-Southern Oscillation (ENSO), an ocean-atmosphere coupled oscillation over the equatorial Pacific, is the most important source of global climate variability on inter-annual time scales. It has substantial environmental and socio-economic consequences such as devastation of South American fish populations and increased forest fires in Indonesia. The instrumental ENSO record is too short for analysing long-term trends and variability, hence proxy data is used to extend the record. However, different proxy sources have produced varying reconstructions of ENSO, with some evidence for a temperature-precipitation divergence in ENSO trends over the past millennium, in particular during the Mediaeval Climate Anomaly (MCA; AD 800-1300) and the Little Ice Age (LIA; AD 1400-1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using EOF-based weighting to create two new large-scale ENSO reconstructions derived independently from precipitation proxies and temperature proxies respectively. The method is developed and validated using pseudoproxy experiments that address the effects of proxy dating error, resolution and noise to improve uncertainty estimations. The precipitation ENSO reconstruction displays a significantly more El Niño-like state during the LIA than the MCA, while the temperature reconstruction shows no significant difference. The trends shown in the precipitation ENSO reconstruction are relatively robust to variations in the precipitation EOF pattern. However, the temperature reconstruction suffers significantly from a lack of high-quality, favourably located proxy records, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records.

Current and historical concentrations of poly and perfluorinated compounds in sediments of the northern Great Lakes - Superior, Huron, and Michigan.

PubMed

Codling, Garry; Hosseini, Soheil; Corcoran, Margaret B; Bonina, Solidea; Lin, Tian; Li, An; Sturchio, Neil C; Rockne, Karl J; Ji, Kyunghee; Peng, Hui; Giesy, John P

2018-05-01

Current and historical concentrations of 22 poly- and perfluorinated compounds (PFASs) in sediment collected from Lake Superior and northern Lake Michigan in 2011 and Lake Huron in 2012 are reported. The sampling was performed in two ways, Ponar grabs of surface sediments for current spatial distribution across the lake and dated cores for multi-decadal temporal trends. Mean concentrations of the sum of PFASs (∑PFASs) were 1.5, 4.6 and 3.1 ng g -1 dry mas (dm) in surface sediments for Lakes Superior, Michigan and Huron, respectively. Of the five Laurentian Lakes, the watersheds of Superior and Huron are the less densely populated by humans, and concentrations observed were typically less and from more diffuse sources, due to lesser urbanization and industrialization. However, some regions of greater concentrations were observed and might indicate more local, point sources. In core samples concentrations ranged from 7 that include perfluoro-n-octane sulfonate (PFOS) bind more strongly to sediment, which resulted in more accurate analyses of temporal trends. Shorter-chain PFASs, such as perfluoro-n-butanoic acid which is the primary replacement for C8 PFASs that have been phased out, are more soluble and were identified in some core layers at depths corresponding to pre-production periods. Thus, analyses of temporal trends of these more soluble compounds in cores of sediments were less accurate. Total elemental fluorine (TF) and extractable organic fluorine (EOF) indicated that identified PFASs were not a significant fraction of fluorine containing compounds in sediment (<0.01% in EOF). Copyright © 2018 Elsevier Ltd. All rights reserved.

Extended-range forecasting of Chinese summer surface air temperature and heat waves

NASA Astrophysics Data System (ADS)

Zhu, Zhiwei; Li, Tim

2018-03-01

Because of growing demand from agricultural planning, power management and activity scheduling, extended-range (5-30-day lead) forecasting of summer surface air temperature (SAT) and heat waves over China is carried out in the present study via spatial-temporal projection models (STPMs). Based on the training data during 1960-1999, the predictability sources are found to propagate from Europe, Northeast Asia, and the tropical Pacific, to influence the intraseasonal 10-80 day SAT over China. STPMs are therefore constructed using the projection domains, which are determined by these previous predictability sources. For the independent forecast period (2000-2013), the STPMs can reproduce EOF-filtered 30-80 day SAT at all lead times of 5-30 days over most part of China, and observed 30-80 and 10-80 day SAT at 25-30 days over eastern China. Significant pattern correlation coefficients account for more than 50% of total forecasts at all 5-30-day lead times against EOF-filtered and observed 30-80 day SAT, and at a 20-day lead time against observed 10-80 day SAT. The STPMs perform poorly in reproducing 10-30 day SAT. Forecasting for the first two modes of 10-30 day SAT only shows useful skill within a 15-day lead time. Forecasting for the third mode of 10-30 day SAT is useless after a 10-day lead time. The forecasted heat waves over China are determined by the reconstructed SAT which is the summation of the forecasted 10-80 day SAT and the lower frequency (longer than 80-day) climatological SAT. Over a large part of China, the STPMs can forecast more than 30% of heat waves within a 15-day lead time. In general, the STPMs demonstrate the promising skill for extended-range forecasting of Chinese summer SAT and heat waves.

Paleoclimatic significance of insoluble microparticle records from Canadian Arctic and Greenland ice cores

NASA Astrophysics Data System (ADS)

Zdanowicz, Christian Michel

1999-10-01

The past and present variability of climate in the Arctic region is investigated using ice core records of atmospheric dust (microparticles) and volcanic aerosols developed from the Canadian Arctic and Greenland. A high- resolution, 10 4-year long proxy record of atmospheric dust deposition is developed from an ice core (P95) drilled through the Penny Ice Cap, Baffin Island. Snowpit studies indicate that dust deposited on the Penny Ice Cap are representative of background mineral aerosol, and demonstrate that the variability of dust fallout is preserved in the P95 core at multi-annual to longer time scales. The P95 dust record reveals a significant increase in dust deposition on the Penny Ice Cap between ca 7500-5000 yr ago. This increase was driven by early to mid-/late Holocene transformations in the Northern Hemisphere landscape (ice cover retreat, postglacial land emergence) and climate (transition to colder, drier conditions) that led to an expansion of sources and enhanced eolian activity. Comparison between dust records in the P95 and GISP2 (Greenland) ice cores shows an increasing divergence between the two records beginning ca 7500 years ago. The effects of Northern Hemisphere atmospheric circulation and snow cover extent on atmospheric dust deposition in the Arctic are evaluated by comparing the P95 dust record with observational data. Changes in dust deposition are strongly linked to modes of the Northern Hemisphere winter circulation. Most prominently, an inverse relationship between the P95 dust record and the intensity of the winter Siberian High accounts for over 50% of the interannual variance of these two parameters over the period 1899-1995. On inter- to multi- annual time scales, the P95 dust record is significantly anticorrelated with variations in spring, and to a lesser extent fall, snow cover extent in the mid-latitude interior regions of Eurasia and North America. These relationships account for an estimated 10 to 20% of variance in the P95 dust record. An empirical orthogonal function (EOF) analysis is used to investigate patterns of temporal covariance among insoluble microparticles and major ions deposited in the GISP2 and P95 ice cores. Dust and major ions covary strongly in the GISP2 late glacial record but are uncorrelated in both the GISP2 and P95 Holocene records. Companion EOF analyses of the Holocene records identify distinctive covariance patterns among microparticles and/or major ions that are associated with certain aerosols types or with source-specific air masses reaching the Arctic, providing further evidence of increased regional-scale climatic and atmospheric variability over the last ~ 12,000 years. The atmospheric and climatic impact of the early Holocene eruption of Mount Mazama (Crater Lake, Oregon) is evaluated from the GISP2 ice core record of volcanically- derived sulfate and ash particles. The calendrical age of the eruption is determined to be 7627 +/- 150 cal yr B.P. The GISP2 sulfate record suggests a total stratospheric aerosol loading between 88 and 224 Mt spread over a ~ 6-year period following the eruption. From these figures, the Mount Mazama eruption is estimated to have depressed temperature by ~ 0.6 to 0.7°C at mid- to high northern latitudes. (Abstract shortened by UMI.)

Secondary iris recognition method based on local energy-orientation feature

NASA Astrophysics Data System (ADS)

Huo, Guang; Liu, Yuanning; Zhu, Xiaodong; Dong, Hongxing

2015-01-01

This paper proposes a secondary iris recognition based on local features. The application of the energy-orientation feature (EOF) by two-dimensional Gabor filter to the extraction of the iris goes before the first recognition by the threshold of similarity, which sets the whole iris database into two categories-a correctly recognized class and a class to be recognized. Therefore, the former are accepted and the latter are transformed by histogram to achieve an energy-orientation histogram feature (EOHF), which is followed by a second recognition with the chi-square distance. The experiment has proved that the proposed method, because of its higher correct recognition rate, could be designated as the most efficient and effective among its companion studies in iris recognition algorithms.

North Atlantic Oscillation influence and weather types associated with winter total and extreme precipitation events in Spain

NASA Astrophysics Data System (ADS)

Queralt, S.; Hernández, E.; Barriopedro, D.; Gallego, D.; Ribera, P.; Casanova, C.

2009-12-01

An analysis of winter intensity and frequency of precipitation is presented, based on 102 daily precipitation stations over Spain and the Balearic Islands for the 1997-2006 decade. Precipitation stations have been merged in the eight different regions which compose the analyzed area by the use of an EOF analysis. NAO influence on the intensity and frequency of precipitation of each region is described in terms of mean precipitation, mean rain frequency, the number of extreme events, changes in the precipitation distribution and the prevalent synoptic configuration. Results indicate a non-stationary response; NAO signal being more evident in mid-late winter. Strong regional differences in the response to NAO are also found, which vary according to the specific character of the precipitation under analysis. Thus, NAO exerts a clear effect on the intensity of total and extreme precipitation rates in northern and westernmost Spanish regions, whereas the frequency of precipitation is clearly affected by NAO in central and southwestern areas. While the correlation between NAO and precipitation is negative for most of the analyzed area, two regions reveal positive responses to NAO in total precipitation occurrence and intensity for specific months. Further analyses reveal asymmetric responses to opposite phases of NAO in the precipitation distributions of some regions. The complex regional relationship between NAO and precipitation is also revealed through the modulation of the former in the preferred Circulation Weather Types associated to precipitation in each region. This spatially non-homogeneous NAO signal stresses the need of caution when employing Iberian precipitation as a proxy for NAO.

Surface Water and Energy Budgets for Sub-Saharan Africa in GFDL Coupled Climate Model

NASA Astrophysics Data System (ADS)

Tian, D.; Wood, E. F.; Vecchi, G. A.; Jia, L.; Pan, M.

2015-12-01

This study compare surface water and energy budget variables from the Geophysical Fluid Dynamics Laboratory (GFDL) FLOR models with the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), Princeton University Global Meteorological Forcing Dataset (PGF), and PGF-driven Variable Infiltration Capacity (VIC) model outputs, as well as available observations over the sub-Saharan Africa. The comparison was made for four configurations of the FLOR models that included FLOR phase 1 (FLOR-p1) and phase 2 (FLOR-p2) and two phases of flux adjusted versions (FLOR-FA-p1 and FLOR-FA-p2). Compared to p1, simulated atmospheric states in p2 were nudged to the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. The seasonal cycle and annual mean of major surface water (precipitation, evapotranspiration, runoff, and change of storage) and energy variables (sensible heat, ground heat, latent heat, net solar radiation, net longwave radiation, and skin temperature) over a 34-yr period during 1981-2014 were compared in different regions in sub-Saharan Africa (West Africa, East Africa, and Southern Africa). In addition to evaluating the means in three sub-regions, empirical orthogonal functions (EOFs) analyses were conducted to compare both spatial and temporal characteristics of water and energy budget variables from four versions of GFDL FLOR, NCEP CFSR, PGF, and VIC outputs. This presentation will show how well each coupled climate model represented land surface physics and reproduced spatiotemporal characteristics of surface water and energy budget variables. We discuss what caused differences in surface water and energy budgets in land surface components of coupled climate model, climate reanalysis, and reanalysis driven land surface model. The comparisons will reveal whether flux adjustment and nudging would improve depiction of the surface water and energy budgets in coupled climate models.

Hydrology in Central Europe - a Comparison Between Data from the GRACE Satellite Mission and Ground Superconducting Gravimeters

NASA Astrophysics Data System (ADS)

Crossley, D.; de Linage, C.; Boy, J.-P.; Hinderer, J.

2009-04-01

The surface gravity field is subject to many influences of mass redistribution within the Earth system, operating at the microgal (10-8 m s-2) level and at timescales from minutes to years. We include deformation within the Earth (tides, polar motion), motions within the atmosphere (local, regional, and global loading; also mass attractions), the oceans (non-tidal currents), and near-surface hydrology derived from rainfall (local, regional, and global contributions). In central Europe a network of 7 superconducting gravimeters (the only instrument with the required resolution for this type of work) has been operating for many years, recording variations at the sub-microgal level. Hydrology is the largest component in the un-modelled residual signal, most of which comes from an area within a few hundred m of the instrument. We use data from 2002-2007 to construct a regionalized ground gravity data set that is analyzed by Principal Component (EOF) analysis to extract the predominantly seasonal signal common to all stations. This we compare with the GRACE-derived field using solutions from GFZ Potsdam, CSR Texas, and GRGS Toulouse. There is very good agreement on the phase of the two different types of data, but the amplitude of the ground signal is complicated by the local hydrology around several of the stations, which is both above and below the instrument. We show our most recent analysis and compare the results with the GLDAS global hydrology model from NASA.

Global-Local Interactions Modulate Tropical Moisture Exports to the Ohio River Basin

NASA Astrophysics Data System (ADS)

Doss-Gollin, J.; Farnham, D. J.; Lall, U.

2016-12-01

Regional-scale extreme rainfall and flooding are temporally and spatially associated with the occurrence of tropical moisture exports (TMEs) in the Ohio River Basin (ORB). TMEs are related to but not synonymous with atmospheric rivers, which refer to specific filiamentary organizational processes. TMEs to the ORB may be driven by strong, persistent ridging over the Eastern United States and troughing over the Central United States, creating favorable conditions for southerly flow and moisture transport from the Gulf of Mexico and Caribbean Sea. However, the strong inter-annual variation in TME activity over the ORB suggests dependence on global-scale features of the atmospheric circulation. We suggest that this synoptic dipole pattern may be viewed as the passage of one or more high-wavenumber, transient Rossby waves. We build a multi-level hierarchical Bayesian model in which the probability distribution of TME entering the ORB is a function of the phase and amplitude of the traveling waves. In turn, the joint distribution of the phase and amplitude of this wave is modulated by hemispheric-scale features of the atmospheric and oceanic circulation, and the amplitude and synchronization of quasi-stationary Rossby waves with wavenumber 1-4. Our approach bridges information about different features of the atmospheric circulation which inform the predictability of TME at multiple time scales and develops existing understanding of the atmospheric drivers of TMEs beyond existing composite and EOF studies.

Seasonal Mass Changes and Crustal Vertical Deformations Constrained by GPS and GRACE in Northeastern Tibet

PubMed Central

Pan, Yuanjin; Shen, Wen-Bin; Hwang, Cheinway; Liao, Chaoming; Zhang, Tengxu; Zhang, Guoqing

2016-01-01

Surface vertical deformation includes the Earth’s elastic response to mass loading on or near the surface. Continuous Global Positioning System (CGPS) stations record such deformations to estimate seasonal and secular mass changes. We used 41 CGPS stations to construct a time series of coordinate changes, which are decomposed by empirical orthogonal functions (EOFs), in northeastern Tibet. The first common mode shows clear seasonal changes, indicating seasonal surface mass re-distribution around northeastern Tibet. The GPS-derived result is then assessed in terms of the mass changes observed in northeastern Tibet. The GPS-derived common mode vertical change and the stacked Gravity Recovery and Climate Experiment (GRACE) mass change are consistent, suggesting that the seasonal surface mass variation is caused by changes in the hydrological, atmospheric and non-tidal ocean loads. The annual peak-to-peak surface mass changes derived from GPS and GRACE results show seasonal oscillations in mass loads, and the corresponding amplitudes are between 3 and 35 mm/year. There is an apparent gradually increasing gravity between 0.1 and 0.9 μGal/year in northeast Tibet. Crustal vertical deformation is determined after eliminating the surface load effects from GRACE, without considering Glacial Isostatic Adjustment (GIA) contribution. It reveals crustal uplift around northeastern Tibet from the corrected GPS vertical velocity. The unusual uplift of the Longmen Shan fault indicates tectonically sophisticated processes in northeastern Tibet. PMID:27490550

Observational evidence for the relationship between spring soil moisture and June rainfall over the Indian region

NASA Astrophysics Data System (ADS)

KanthaRao, B.; Rakesh, V.

2018-05-01

Understanding the relationship between gradually varying soil moisture (SM) conditions and monsoon rainfall anomalies is crucial for seasonal prediction. Though it is an important issue, very few studies in the past attempted to diagnose the linkages between the antecedent SM and Indian summer monsoon rainfall. This study examined the relationship between spring (April-May) SM and June rainfall using observed data during the period 1979-2010. The Empirical Orthogonal Function (EOF) analyses showed that the spring SM plays a significant role in June rainfall over the Central India (CI), South India (SI), and North East India (NEI) regions. The composite anomaly of the spring SM and June rainfall showed that excess (deficit) June rainfall over the CI was preceded by wet (dry) spring SM. The anomalies in surface-specific humidity, air temperature, and surface radiation fluxes also supported the existence of a positive SM-precipitation feedback over the CI. On the contrary, excess (deficit) June rainfall over the SI and NEI region were preceded by dry (wet) spring SM. The abnormal wet (dry) SM over the SI and NEI decreased (increased) the 2-m air temperature and increased (decreased) the surface pressure compared to the surrounding oceans which resulted in less (more) moisture transport from oceans to land (negative SM-precipitation feedback over the Indian monsoon region).

A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

PubMed

Ludewig, Ronny; Nietzsche, Sandor; Scriba, Gerhard K E

2011-01-01

A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Response of ENSO amplitude to global warming in CESM large ensemble: uncertainty due to internal variability

NASA Astrophysics Data System (ADS)

Zheng, Xiao-Tong; Hui, Chang; Yeh, Sang-Wook

2018-06-01

El Niño-Southern Oscillation (ENSO) is the dominant mode of variability in the coupled ocean-atmospheric system. Future projections of ENSO change under global warming are highly uncertain among models. In this study, the effect of internal variability on ENSO amplitude change in future climate projections is investigated based on a 40-member ensemble from the Community Earth System Model Large Ensemble (CESM-LE) project. A large uncertainty is identified among ensemble members due to internal variability. The inter-member diversity is associated with a zonal dipole pattern of sea surface temperature (SST) change in the mean along the equator, which is similar to the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV) in the unforced control simulation. The uncertainty in CESM-LE is comparable in magnitude to that among models of the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting the contribution of internal variability to the intermodel uncertainty in ENSO amplitude change. However, the causations between changes in ENSO amplitude and the mean state are distinct between CESM-LE and CMIP5 ensemble. The CESM-LE results indicate that a large ensemble of 15 members is needed to separate the relative contributions to ENSO amplitude change over the twenty-first century between forced response and internal variability.

Comparison of velocity and temperature time series data analysis in experiments on the thermally driven rotating annulus

NASA Astrophysics Data System (ADS)

von Larcher, Thomas; Harlander, Uwe; Alexandrov, Kiril; Wang, Yongtai

2010-05-01

The model of the differentially heated, rotating cylindrical gap filled with a fluid is since more than four decades extensively used for laboratory experiments of baroclinic wave interactions, and a number of data acquisition techniques are applied e.g. to unhide regular waves of different zonal wave number, to better understand the transition to the quasi-chaotic regime, and to reveal the underlying dynamical processes of complex wave flows. In our experiments presented here, we make use of non-intrusive measurement techniques of a quite different nature. While the high accurate Laser-Doppler-Velocimetry (LDV ) is used for measurements of the radial velocity component at equidistant azimuthal positions, a high sensitive thermographic camera, which resolution allows for resolving fine scale structures, measures the surface temperature field. Both sets of time series data are analyzed by using multivariate statistical techniques. While the LDV data sets are studied by applying the Multi-Channel Singular Spectrum Analysis (M - SSA), the temperature data sets are analyzed by applying the Empirical Orthogonal Functions (EOF ). In addition, the temperature data are processed in a way to become comparable to the LDV data, i.e. reducing the size of the data set in such a manner that the temperature measurements would imaginary be performed at equidistant azimuthal positions only. This approach initially results in a great loss of information. But applying the M - SSA to the reduced temperature data sets enable us not only to compare the data analysis methods but also to reclassify the results yielded with the LDV data analysis. The measurements are performed at particular parameter points, where our former studies show that kinds of complex wave patterns occur [1, 2]. For example, we found a dominant and a weak mode in the 3-4 wave transition region. This finding confirms earlier ideas on wave dispersion in transition regions between regular waves. Increasing the annulus' rotation leads to a growth of the weak mode until this mode becomes the dominant one. [1] Th. von Larcher and C. Egbers, Experiments on transitions of baroclinic waves in a differentially heated rotating annulus, Nonlinear Processes in Geophysics, 2005, 12, 1033-1041, NPG Print: ISSN 1023-5809, NPG Online: ISSN 1607-7946 [2] U. Harlander, Th. von Larcher, Y. Wang and C. Egbers, PIV- and LDV-measurements of baroclinic wave interactions in a thermally driven rotating annulus, Experiments in Fluids, 2009, DOI: 10.1007/s00348-009-0792-5

Precipitation interannual variability and predictions for West Africa from the National Multi-Model Ensemble dataset

NASA Astrophysics Data System (ADS)

Thiaw, W. M.

2013-12-01

The ability of coupled climate models from the national multi-model ensemble (NMME) dataset to reproduce the basic state and interannual variability of precipitation in West Africa and associated teleconnections is examined. The analysis is for the period 1982-2010 for most of the models, which corresponds to the NMME hindcast period, except for the CFS version 1 (CFSv1) which covers the period 1981-2009. The satellite based CPC African Rainfall Climatology (ARC2) data is used as proxy for observed rainfall and to validate the models. We examine rainfall patterns throughout the year. Models are able to reproduce the north-south migration of precipitation from winter and spring when the area of maximum precipitation is located in Central Africa and the Gulf of Guinea region to the summer when it is in northern Sub-Saharan Africa, and the later return to the south. Models also appropriately place precipitation over the Gulf of Guinea region during the equinoxes in MAM and OND. However, there are considerable differences in the representation of the intensities and locations of the rainfall. Three of the models including the two versions of the NCEP CFS and the NASA models also have a systematic dry (wet) bias over the Sahel (Gulf of Guinea region) during the summer rainfall season, while the others show alternating wet and dry biases across West Africa. All models have spatially averaged values of standard deviation lower than that observed. Models are also able to reproduce to some extent the main features of the precipitation variability maximum, but again with deficiencies in the amplitudes and locations. The areas of highest variability are generally depicted, but there are significant differences among the models, and even between the two versions of the CFS. Teleconnections in the models are investigated by first conducting an EOF in the precipitation anomaly fields and then perform a regression of the first or second EOF time series onto the global SST. Focusing on JAS rainfall season, only the CFSv1 and the NASA models were able to depict the dipole pattern between the Sahel and the Gulf of Guinea rainfall. However, none of the models was able to reproduce the observed upward trend of Sahel rainfall in the last decade. The relationship to SST is also examined. The observed influence of tropical north Atlantic SST on the Sahel rainfall is only partially represented even in the CFSv1, while the NASA model inconsistently emphasizes the role of the tropical South Atlantic. A majority of the models show a partial ENSO teleconnection combined with the tropical south Atlantic mode. However, observations indicate that the influence of ENSO on northern Sub-Saharan summer rainfall has been very weak over the past 30 years. Results for MAM, and OND are also presented. The influence of model errors on the predictions of African rainfall is presented. Canonical correlation analysis (CCA) is employed to correct the model simulations. A new ensemble based on models corrected forecasts is then formed and the results are presented.

Analysis of acrylamide in food products by in-line preconcentration capillary zone electrophoresis.

PubMed

Bermudo, Elisabet; Núñez, Oscar; Puignou, Luis; Galceran, Maria Teresa

2006-09-29

Two in-line preconcentration capillary zone electrophoresis (CZE) methods (field amplified sample injection (FASI) and stacking with sample matrix removal (LVSS)) have been evaluated for the analysis of acrylamide (AA) in foodstuffs. To allow the determination of AA by CZE, it was derivatized using 2-mercaptobenzoic acid. For FASI, the optimum conditions were water at pH > or = 10 adjusted with NH3 as sample solvent, 35 s hydrodynamic injection (0.5 psi) of a water plug, 35 s of electrokinetic injection (-10 kV) of the sample, and 6s hydrodynamic injection (0.5 psi) of another water plug to prevent AA removal by EOF. In stacking with sample matrix removal, the reversal time was found to be around 3.3 min. A 40 mM phosphate buffer (pH 8.5) was used as carrier electrolyte for CZE separation in both cases. For both FASI and LVSS methods, linear calibration curves over the range studied (10-1000 microg L(-1) and 25-1000 microg L(-1), respectively), limit of detection (LOD) on standards (1 microg L(-1) for FASI and 7 microg L(-1) for LVSS), limit of detection on samples (3 ng g(-1) for FASI and 20 ng g(-1) for LVSS) and both run-to-run (up to 14% for concentration and 0.8% for time values) and day-to-day precisions (up to 16% and 5% for concentration and time values, respectively) were established. Due to the lower detection limits obtained with the FASI-CZE this method was applied to the analysis of AA in different foodstuffs such as biscuits, cereals, crisp bread, snacks and coffee, and the results were compared with those obtained by LC-MS/MS.

Ligase Detection Reaction for the Analysis of Point Mutations using Free Solution Conjugate Electrophoresis in a Polymer Microfluidic Device

PubMed Central

Sinville, Rondedrick; Coyne, Jennifer; Meagher, Robert J.; Cheng, Yu-Wei; Barany, Francis; Barron, Annelise; Soper, Steven A.

2010-01-01

We have developed a new method for the analysis of low abundant point mutations in genomic DNA using a combination of an allele-specific ligase detection reaction (LDR) with free-solution conjugate electrophoresis (FSCE) to generate and analyze the genetic products. FSCE eliminates the need for a polymer sieving matrix by conjugating chemically synthesized polyamide “drag-tags” onto the LDR primers. The additional drag of the charge-neutral drag-tag breaks the linear scaling of the charge-to-friction ratio of DNA and enables size-based separations of DNA in free solution using electrophoresis with no sieving matrix. We successfully demonstrate the conjugation of polyamide drag-tags onto a set of four LDR primers designed to probe the K-ras oncogene for mutations highly associated with colorectal cancer, the simultaneous generation of fluorescently-labeled LDR/drag-tagged (LDR-dt) products in a multiplexed, single-tube format with mutant:wild-type ratios as low as 1:100, respectively, and the single-base, high-resolution separation of all four LDR-dt products. Separations were conducted in free solution with no polymer network using both a commercial capillary array electrophoresis (CAE) system and a poly(methylmethacrylate), PMMA, microchip replicated via hot-embossing with only a Tris-based running buffer containing additives to suppress the electroosmotic flow (EOF). Typical analysis times for LDR-dt conjugates were 11 min using the CAE system and as low as 85 s for the PMMA microchips. With resolution comparable to traditional gel-based CAE, FSCE along with microchip electrophoresis decreased the separation time by more than a factor of 40. PMID:19053073

Selection of optimal complexity for ENSO-EMR model by minimum description length principle

NASA Astrophysics Data System (ADS)

Loskutov, E. M.; Mukhin, D.; Mukhina, A.; Gavrilov, A.; Kondrashov, D. A.; Feigin, A. M.

2012-12-01

One of the main problems arising in modeling of data taken from natural system is finding a phase space suitable for construction of the evolution operator model. Since we usually deal with strongly high-dimensional behavior, we are forced to construct a model working in some projection of system phase space corresponding to time scales of interest. Selection of optimal projection is non-trivial problem since there are many ways to reconstruct phase variables from given time series, especially in the case of a spatio-temporal data field. Actually, finding optimal projection is significant part of model selection, because, on the one hand, the transformation of data to some phase variables vector can be considered as a required component of the model. On the other hand, such an optimization of a phase space makes sense only in relation to the parametrization of the model we use, i.e. representation of evolution operator, so we should find an optimal structure of the model together with phase variables vector. In this paper we propose to use principle of minimal description length (Molkov et al., 2009) for selection models of optimal complexity. The proposed method is applied to optimization of Empirical Model Reduction (EMR) of ENSO phenomenon (Kravtsov et al. 2005, Kondrashov et. al., 2005). This model operates within a subset of leading EOFs constructed from spatio-temporal field of SST in Equatorial Pacific, and has a form of multi-level stochastic differential equations (SDE) with polynomial parameterization of the right-hand side. Optimal values for both the number of EOF, the order of polynomial and number of levels are estimated from the Equatorial Pacific SST dataset. References: Ya. Molkov, D. Mukhin, E. Loskutov, G. Fidelin and A. Feigin, Using the minimum description length principle for global reconstruction of dynamic systems from noisy time series, Phys. Rev. E, Vol. 80, P 046207, 2009 Kravtsov S, Kondrashov D, Ghil M, 2005: Multilevel regression modeling of nonlinear processes: Derivation and applications to climatic variability. J. Climate, 18 (21): 4404-4424. D. Kondrashov, S. Kravtsov, A. W. Robertson and M. Ghil, 2005. A hierarchy of data-based ENSO models. J. Climate, 18, 4425-4444.

Electroosmotic flow mixing in zigzag microchannels.

PubMed

Chen, Jia-Kun; Yang, Ruey-Jen

2007-03-01

In this study we performed numerical and experimental investigations into the mixing of EOFs in zigzag microchannels with two different corner geometries, namely sharp corners and flat corners. In the zigzag microchannel with sharp corners, the flow travels more rapidly near the inner wall of the corner than near the outer wall as a result of the higher electric potential drop. The resulting velocity gradient induces a racetrack effect, which enhances diffusion within the fluid and hence improves the mixing performance. The simulation results reveal that the mixing index is approximately 88.83%. However, the sharp-corner geometry causes residual liquid or bubbles to become trapped in the channel at the point where the flow is almost stationary, when the channel is in the process of cleaning. Accordingly, a zigzag microchannel with flat-corner geometry is developed. The flat-corner geometry forms a convergent-divergent type nozzle which not only enhances the mixing performance in the channel, but also prevents the accumulation of residual liquid or bubbles. Scaling analysis reveals that this corner geometry leads to an effective increase in the mixing length. The experimental results reveal that the mixing index is increased to 94.30% in the flat-corner zigzag channel. Hence, the results demonstrate that the mixing index of the flat-corner zigzag channel is better than that of the conventional sharp-corner microchannel. Finally, the results of Taguchi analysis indicate that the attainable mixing index is determined primarily by the number of corners in the microchannel and by the flow passing height at each corner.

Statistical downscaling of IPCC sea surface wind and wind energy predictions for U.S. east coastal ocean, Gulf of Mexico and Caribbean Sea

NASA Astrophysics Data System (ADS)

Yao, Zhigang; Xue, Zuo; He, Ruoying; Bao, Xianwen; Song, Jun

2016-08-01

A multivariate statistical downscaling method is developed to produce regional, high-resolution, coastal surface wind fields based on the IPCC global model predictions for the U.S. east coastal ocean, the Gulf of Mexico (GOM), and the Caribbean Sea. The statistical relationship is built upon linear regressions between the empirical orthogonal function (EOF) spaces of a cross- calibrated, multi-platform, multi-instrument ocean surface wind velocity dataset (predictand) and the global NCEP wind reanalysis (predictor) over a 10 year period from 2000 to 2009. The statistical relationship is validated before applications and its effectiveness is confirmed by the good agreement between downscaled wind fields based on the NCEP reanalysis and in-situ surface wind measured at 16 National Data Buoy Center (NDBC) buoys in the U.S. east coastal ocean and the GOM during 1992-1999. The predictand-predictor relationship is applied to IPCC GFDL model output (2.0°×2.5°) of downscaled coastal wind at 0.25°×0.25° resolution. The temporal and spatial variability of future predicted wind speeds and wind energy potential over the study region are further quantified. It is shown that wind speed and power would significantly be reduced in the high CO2 climate scenario offshore of the mid-Atlantic and northeast U.S., with the speed falling to one quarter of its original value.

Temporal–Spatial Surface Seasonal Mass Changes and Vertical Crustal Deformation in South China Block from GPS and GRACE Measurements

PubMed Central

He, Meilin; Shen, Wenbin; Chen, Ruizhi; Ding, Hao; Guo, Guangyi

2017-01-01

The solid Earth deforms elastically in response to variations of surface atmosphere, hydrology, and ice/glacier mass loads. Continuous geodetic observations by Global Positioning System (CGPS) stations and Gravity Recovery and Climate Experiment (GRACE) record such deformations to estimate seasonal and secular mass changes. In this paper, we present the seasonal variation of the surface mass changes and the crustal vertical deformation in the South China Block (SCB) identified by GPS and GRACE observations with records spanning from 1999 to 2016. We used 33 CGPS stations to construct a time series of coordinate changes, which are decomposed by empirical orthogonal functions (EOFs) in SCB. The average weighted root-mean-square (WRMS) reduction is 38% when we subtract GRACE-modeled vertical displacements from GPS time series. The first common mode shows clear seasonal changes, indicating seasonal surface mass re-distribution in and around the South China Block. The correlation between GRACE and GPS time series is analyzed which provides a reference for further improvement of the seasonal variation of CGPS time series. The results of the GRACE observations inversion are the surface deformations caused by the surface mass change load at a rate of about −0.4 to −0.8 mm/year, which is used to improve the long-term trend of non-tectonic loads of the GPS vertical velocity field to further explain the crustal tectonic movement in the SCB and surroundings. PMID:29301236

Morphometry, asymmetry and variations of cerebral sulci on superolateral surface of cerebrum in autopsy cases.

PubMed

Gonul, Yucel; Songur, Ahmet; Uzun, Ibrahim; Uygur, Ramazan; Alkoc, Ozan Alper; Caglar, Veli; Kucuker, Hudaverdi

2014-09-01

The cerebral sulci are known as main microanatomical borders that serve as a gateway and surgical passage to reach the ventricles or to the deeper lesions. It is a matter of curiosity that whether there is a convergence between the morphological asymmetry and the functional asymmetry, and also its significance in surgery. The aim of this study is make morphometric measurements and evaluate asymmetry of several sulci on the lateral aspects of the cerebrum in regard to main sulci and related reference key points. A total of 100 cerebral hemispheres from 50 autopsy cadavers were examined. The lengths of several sulci on the superolateral aspect of the hemispheres and the distances between the sulci and nearby sulci and the reference key points were measured. Encountered variations were examined and photographed. Evaluation of the variations: superior frontal sulcus (SFS), inferior frontal sulcus, superior temporal sulcus (STS), precentral sulcus and postcentral sulcus were found to be discontinuous in 60, 46, 41, 84 and 70 % of the hemispheres, respectively. Evaluation of the asymmetry: the distances between SFS posterior end and longitudinal fissure, STS posterior end and lateral sulcus posterior end, as well as lengths of external occipital fissure (EOF), and discontinuous course of STS were significantly different between left and right hemispheres. There is usually a morphological partial asymmetry between the right and left hemispheres for any individual. Also, some of our measurements were found to be compatible with the ones in the literature, while others were incompatible.

Towards uncertainty estimation for operational forecast products - a multi-model-ensemble approach for the North Sea and the Baltic Sea

NASA Astrophysics Data System (ADS)

Golbeck, Inga; Li, Xin; Janssen, Frank

2014-05-01

Several independent operational ocean models provide forecasts of the ocean state (e.g. sea level, temperature, salinity and ice cover) in the North Sea and the Baltic Sea on a daily basis. These forecasts are the primary source of information for a variety of information and emergency response systems used e.g. to issue sea level warnings or carry out oil drift forecast. The forecasts are of course highly valuable as such, but often suffer from a lack of information on their uncertainty. With the aim of augmenting the existing operational ocean forecasts in the North Sea and the Baltic Sea by a measure of uncertainty a multi-model-ensemble (MME) system for sea surface temperature (SST), sea surface salinity (SSS) and water transports has been set up in the framework of the MyOcean-2 project. Members of MyOcean-2, the NOOS² and HIROMB/BOOS³ communities provide 48h-forecasts serving as inputs. Different variables are processed separately due to their different physical characteristics. Based on the so far collected daily MME products of SST and SSS, a statistical method, Empirical Orthogonal Function (EOF) analysis is applied to assess their spatial and temporal variability. For sea surface currents, progressive vector diagrams at specific points are consulted to estimate the performance of the circulation models especially in hydrodynamic important areas, e.g. inflow/outflow of the Baltic Sea, Norwegian trench and English Channel. For further versions of the MME system, it is planned to extend the MME to other variables like e.g. sea level, ocean currents or ice cover based on the needs of the model providers and their customers. It is also planned to include in-situ data to augment the uncertainty information and for validation purposes. Additionally, weighting methods will be implemented into the MME system to develop more complex uncertainty measures. The methodology used to create the MME will be outlined and different ensemble products will be presented. In addition, some preliminary results based on the statistical analysis of the uncertainty measures provide first estimates of the regional and temporal performance of the ocean models for each parameter. ²Northwest European Shelf Operational Oceanography System ³High-resolution Operational Model of the Baltic / Baltic Operational Oceanographic System

Long-period sea-level variations in the Mediterranean

NASA Astrophysics Data System (ADS)

Zerbini, Susanna; Raicich, Fabio; Bruni, Sara; del Conte, Sara; Errico, Maddalena; Prati, Claudio; Santi, Efisio

2016-04-01

Since the beginning of its long-lasting lifetime, the Wegener initiative has devoted careful consideration to studying sea-level variations/changes across the Mediterranean Sea. Our study focuses on several long-period sea-level time series (from end of 1800 to 2012) acquired in the Mediterranean by tide gauge stations. In general, the analysis and interpretation of these data sets can provide an important contribution to research on climate change and its impacts. We have analyzed the centennial sea-level time series of six fairly well documented tide gauges. They are: Marseille, in France, Alicante in Spain, Genoa, Trieste, Venice and Marina di Ravenna (formerly Porto Corsini), in Italy. The data of the Italian stations of Marina di Ravenna and Venice clearly indicate that land subsidence is responsible for most of the observed rate of relative sea level rise. It is well known that, in the two areas, subsidence is caused by both natural processes and human activities. For these two stations, using levelling data of benchmarks at, and/or close to, the tide gauges, and for the recent years, also GPS and InSAR height time series, modelling of the long-period non-linear behavior of subsidence was successfully accomplished. After removing the land vertical motions, the estimate of the linear long-period sea-level rise at all six stations yielded remarkably consistent values, between +1,2 and +1,3 mm/yr, with associated errors ranging from ±0,2 to ±0,3 mm/yr (95% confidence interval), which also account for the statistical autocorrelation of the time series. These trends in the Mediterranean area are lower than the global mean rate of 1,7±0,2 mm/yr (1901-2010) presented by the IPCC in its 5th Assessment Report; however, they are in full agreement with a global mean sea-level rise estimate, over the period 1901-1990, recently published by Hay et al. (2015, doi:10.1038/nature14093) and obtained using probabilistic techniques that combine sea-level records with physics-based and model-derived geometries of the contributing processes. An EOF analysis (Empirical Orthogonal Functions) has also been carried out on the six sea-level time series to identify the dominant modes of variability.

Application of capillary electrophoresis for organic acid analysis in herbal studies.

PubMed

Fung, Y S; Tung, H S

2001-07-01

A capillary electrophoresis (CE) procedure has been developed for the separation of 25 inorganic and organic acid anions using a buffer system consisting of 15 mM tris(hydroxymethyl)aminomethane, 3 mM 1,2,4-benzenetricarboxylic acid, 1.5 mM tetraethylenepentaamine (TEPA) and 20% methanol with pH adjusted to 8.4. A good separation of organic acids extracted from a mixture of Chinese traditional medicine (TCM) containing three herbs, Flos chrysthemi, Spica prunellae, and Folium mori was obtained using the procedure developed with satisfactory working range (0.20-77 mg/g), low detection limit (90-190 microg/g), and good repeatability (relative standard deviation 4.47-6.99%, n = 4). A satisfactory extraction of organic acids was achieved within 20 min using 0.1 M NaOH. The addition of TEPA to provide a reduced electroosmotic flow (EOF) environment was shown to remove interfering organic compounds extracted from TCM. The applicability of using organic acids as markers for determining the mixing ratio of constituent herbs for a TCM mixture was investigated using a three-component mixture with a 1:1:1 mixing ratio. A satisfactory mixing ratio of 1.04:1.09:0.98 was obtained using the methodology developed based on organic acids as markers. The application of our method for determining more complicated TCM mixtures has been discussed.

1D-VAR Retrieval Using Superchannels

NASA Technical Reports Server (NTRS)

Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen

2008-01-01

Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.

Enhancement of Electrokinetically-Driven Flow Mixing in Microchannel with Added Side Channels

NASA Astrophysics Data System (ADS)

Yang, Ruey-Jen; Wu, Chien-Hsien; Tseng, Tzu-I; Huang, Sung-Bin; Lee, Gwo-Bin

2005-10-01

Electroosmotic flow (EOF) in microchannels is restricted to low Reynolds number regimes. Since the inertial forces are extremely weak in such regimes, turbulent conditions do not readily develop. Therefore, species mixing occurs primarily via diffusion, with the result that extended mixing channels are generally required. The present study considers a T-shaped microchannel configuration with a mixing channel of width W=280 μm. Computational fluid dynamics simulations and experiments were performed to investigate the influence on the mixing efficiency of various geometrical parameters, including the side-channel width, the side-channel separation, and the number of side-channel pairs. The influence of different applied voltages is also considered. The numerical results reveal that the mixing efficiency can be enhanced to yield a fourfold improvement by incorporating two pairs of side channels into the mixing channel. It was also found that the mixing performance depends significantly upon the magnitudes of the applied voltages.

Effects of ionic concentration gradient on electroosmotic flow mixing in a microchannel.

PubMed

Peng, Ran; Li, Dongqing

2015-02-15

Effects of ionic concentration gradient on electroosmotic flow (EOF) mixing of one stream of a high concentration electrolyte solution with a stream of a low concentration electrolyte solution in a microchannel are investigated numerically. The concentration field, flow field and electric field are strongly coupled via concentration dependent zeta potential, dielectric constant and electric conductivity. The results show that the electric field and the flow velocity are non-uniform when the concentration dependence of these parameters is taken into consideration. It is also found that when the ionic concentration of the electrolyte solution is higher than 1M, the electrolyte solution essentially cannot enter the channel due to the extremely low electroosmotic flow mobility. The effects of the concentration dependence of zeta potential, dielectric constant and electric conductivity on electroosmotic flow mixing are studied. Copyright © 2014 Elsevier Inc. All rights reserved.

Precipitation Anomalies in the Tropical Indian Ocean and Possible Links to the Initiation of El Nino

NASA Technical Reports Server (NTRS)

Curtis, Scott; Adler, Robert F.; Huffman, George J.; Starr, David OC. (Technical Monitor)

2001-01-01

A pattern of variability in precipitation and 1000mb zonal winds for the tropical Indian Ocean during, 1979 to 1999 (AtmIO mode) is described using EOFs. The AtmIO mode consists of a cross-equatorial gradient of precipitation anomalies and equatorial wind anomalies of alternating signs on the Equator. The positive phase is defined as enhanced precipitation to the In "n south of the equator, suppressed precipitation to the north, and anomalous westerlies centered on the island of Sumatra. In September-October 1981, February-March 1990, and October-December 1996 the AtmIO mod-, was positive and there was a significant 30-60 day variability in the gradient of precipitation anomalies. These cases coincided with moderate to heavy ,activity in the Madden-Jullan Oscillation (MJO). Links between the AtmIO, MJO, and El Nino are discussed.

The Dynamics of Quantum Discord and Entanglement of Three Atoms Coupled to Three Spatially Separate Cavities

NASA Astrophysics Data System (ADS)

He, Juan; Wu, Tao; Ye, Liu

2013-10-01

In this paper, we study the dynamics of quantum discord and entanglement of three identical two-level atoms simultaneously resonantly interacting with three spatially separate single-mode of high- Q cavities respectively. Taking advantage of the depiction quantum discord and entanglement of formation (EoF), we conclude that the discord and entanglement of atoms and cavities can be mediated by changing some parameters and the maximum values of discord and entanglement are independent on the couplings of cavities and atoms. In particular, there also exists quantum discord sudden death as well as entanglement sudden death and the time interval of the former is shorter than that of the later in the proposed quantum system. It is shown that the discord and entanglement of any two atoms among three atoms can be transferred to the corresponding cavities, and there exists discord and entanglement exchanging between the atoms and the corresponding cavities.

General monogamy relation of multiqubit systems in terms of squared Rényi-α entanglement

NASA Astrophysics Data System (ADS)

Song, Wei; Bai, Yan-Kui; Yang, Mou; Yang, Ming; Cao, Zhuo-Liang

2016-02-01

We prove that the squared Rényi-α entanglement (SR α E ), which is the generalization of entanglement of formation, obeys a general monogamy inequality in an arbitrary N -qubit mixed state. Furthermore, for a class of Rényi-α entanglement, we prove that the monogamy relations of the SR α E have a hierarchical structure when the N -qubit system is divided into k parties. As a by-product, the analytical relation between the Rényi-α entanglement and the squared concurrence is derived for bipartite 2 ⊗d systems. Based on the monogamy properties of SR α E , we can construct the corresponding multipartite entanglement indicators, which still work well even when the indicators based on the squared concurrence and EOF lose their efficacy. In addition, the monogamy property of the μ th power of Rényi-α entanglement is analyzed.

"One-pot" preparation of basic amino acid-silica hybrid monolithic column for capillary electrochromatography.

PubMed

Xu, Hongrui; Xu, Zhendong; Yang, Limin; Wang, Qiuquan

2011-08-01

A novel "one-pot" strategy was developed for the preparation of amino acid (AA)-silica hybrid monolithic column. The basic AA (L-Arginine, L-Lysine and L-Histidine) was covalently incorporated into the silica hybrid skeleton via the epoxy ring-opening reaction between the amine group and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS), which was confirmed by elemental analysis and FT-IR studies, while the basic AA was also found to catalyze the polycondensation of tetramethoxysilane and GPTMS. The average mesopore and macropore sizes of the prepared basic AA-silica hybrid monolithic columns were 3.86 nm and 1.71 μm for the L-Lysine-silica hybrid monolith, 5.38 nm and 4.24 μm for the L-Arginine-silica hybrid monolith, and 6.38 nm and 1.24 μm for the L-Histidine-silica hybrid monolith. The hybrid monolith afforded a zwitterionic stationary phase for CEC, the direction and magnitude of EOF can be controlled by the pH of the mobile phase used. Besides an electrophoretic mechanism, the monoliths behave in a typical hydrophilic interaction with the analytes when ACN percentage in the mobile phase is over 40%. Four polar compounds (toluene, DMF, formamide and thiourea) were tested on the three AA-silica hybrid monolithic columns, and the best separation efficiency was observed in the L-Lysine-silica hybrid monolithic column, its theoretical plate height was down to 5.7 μm for thiourea when 20 mM HCOOH-HCOONH4 containing 20% ACN (pH 4.1) was used as a running buffer. The corresponding theoretical plate number for toluene, DMF, formamide and thiourea were 123,385, 103,620, 121,845 and 105,345 plates/m, respectively. Effective separation of phenols and peptides on the L-Lysine-silica hybrid monolithic column was achieved using CEC. We believe that this strategy paves a way for the easy preparation of various functional silica hybrid monolithic columns, aiming at different separation purposes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the ENSO temperature and specific humidity signals in the troposphere and lower stratosphere with global COSMIC GPS RO observations from June 2006 to June 2014

NASA Astrophysics Data System (ADS)

Chen, Zhiping; Luo, Jia

2017-04-01

The specific humidity and the temperature response of El Niño-Southern Oscillation in the troposphere and lower stratosphere (TLS) over different areas i.e., Niño 3.4 (N3.4); -5˚ S-5˚ N, 180˚ W-180˚ E (G5); -30˚ S-30˚ N, 180˚ W-180˚ E (G30); -60˚ S-60˚ N, 180˚ W-180˚ E (G60); -90˚ S-90˚ N, 180˚ W-180˚ E (G90) were investigated using Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Global Positioning System (GPS) radio occultation (RO) data from June 2006 to June 2014. The empirical orthogonal functions (EOFs) and band-pass filtering with different filtering ranges at different altitudes were used to extract the ENSO-related signals of the specific humidity and the temperature over different altitude levels in the TLS. The time series that has the maximum correlation coefficient between the ENSO-related signals and the ONI were regarded as the strongest response to ENSO. The results confirmed that the ENSO was originated from tropical Pacific Ocean. The lag time and the phase of the maximum specific humidity or temperature response to ENSO event does not show a uniform patern at different altitudes in the troposphere over different areas, but the 1-2 seasons lag ONI was found and consistent with previous study results. The maximum correlation coefficient between the specific humidity and the ONI was about 0.94 at a lag time of 3 months at about 225 hpa altitude over the statistical areas while the maximum correlation coefficients (0.91) between the temperature and the ONI was found at ˜325 hpa altitude level at a lag time of 1 month in the TLS. The well agreement between the ENSO-related signals in the troposphere and the ONI indicates that the specific humidity and temperature derived from COSMIC GPS RO observations are significant for monitoring the ENSO events.

Why is the Skill of the Models in Reproducing MJO and its Impacts on the South American Monsoon Important for Subseasonal Prediction?

NASA Astrophysics Data System (ADS)

Grimm, A. M.; Silva, T. M.; Hirata, F. E.; Martins, G. P.

2017-12-01

The Madden Julian Oscillation (MJO) influences significantly daily precipitation and the frequency of extreme events during the summer South American monsoon (SAM) in important regions of the continent. One of the main features of the SAM, the South Atlantic Convergence Zone (SACZ), extends from central South America over Southeast Brazil and into the subtropical Atlantic Ocean, affecting very densely populated areas in Southeast Brazil. During the austral summer this region is strongly affected by landslides and floods associated with active SACZ, and the extreme precipitation events receive contribution from synoptic and MJO-related intraseasonal variability. Therefore, it is important to assess the observed impacts of the MJO in its different phases and to evaluate the models' skill in reproducing these phases and their impacts on South America in order to explore extended-range predictability of those events. The MJO cycle is divided into 8 phases according to the temporal evolution of the first two observed modes of multivariate EOF analysis of tropical convection and zonal winds. The teleconnections associated with these impacts are analyzed with simulations and influence functions of a simple model. The results show that two of the MJO phases strongly enhance the extreme events in the SACZ region and indicate the responsible mechanisms, lending these events a higher degree of predictability on subseasonal time-scales. Therefore, in selecting models to build a subseasonal-range forecasting scheme for extreme precipitation events, a necessary step is the assessment of their skill in reproducing MJO and its observed impacts on South America. Well-known models of the S2S Project, among them the ECMWF and CFS-v2 models are analyzed. Their reforecasts for weeks 1, 2, 3, 4 are separately projected onto the first two modes of tropical convection and zonal wind variability in order to identify the predicted MJO phases. Although the skill of one of the models in predicting these phases extends to week 4, generally the useful skill does not extend beyond week 3. The simulation of the impacts over South America, especially on the SACZ, is also assessed for selected models.

Why is the Skill of the Models in Reproducing MJO and its Impacts on the South American Monsoon Important for Subseasonal Prediction?

NASA Astrophysics Data System (ADS)

Gross, S.; Wirth, M.; Schäfler, A.; Ewald, F.; Urbanek, B.; Kiemle, C.; Ehret, G.

2016-12-01

The Madden Julian Oscillation (MJO) influences significantly daily precipitation and the frequency of extreme events during the summer South American monsoon (SAM) in important regions of the continent. One of the main features of the SAM, the South Atlantic Convergence Zone (SACZ), extends from central South America over Southeast Brazil and into the subtropical Atlantic Ocean, affecting very densely populated areas in Southeast Brazil. During the austral summer this region is strongly affected by landslides and floods associated with active SACZ, and the extreme precipitation events receive contribution from synoptic and MJO-related intraseasonal variability. Therefore, it is important to assess the observed impacts of the MJO in its different phases and to evaluate the models' skill in reproducing these phases and their impacts on South America in order to explore extended-range predictability of those events. The MJO cycle is divided into 8 phases according to the temporal evolution of the first two observed modes of multivariate EOF analysis of tropical convection and zonal winds. The teleconnections associated with these impacts are analyzed with simulations and influence functions of a simple model. The results show that two of the MJO phases strongly enhance the extreme events in the SACZ region and indicate the responsible mechanisms, lending these events a higher degree of predictability on subseasonal time-scales. Therefore, in selecting models to build a subseasonal-range forecasting scheme for extreme precipitation events, a necessary step is the assessment of their skill in reproducing MJO and its observed impacts on South America. Well-known models of the S2S Project, among them the ECMWF and CFS-v2 models are analyzed. Their reforecasts for weeks 1, 2, 3, 4 are separately projected onto the first two modes of tropical convection and zonal wind variability in order to identify the predicted MJO phases. Although the skill of one of the models in predicting these phases extends to week 4, generally the useful skill does not extend beyond week 3. The simulation of the impacts over South America, especially on the SACZ, is also assessed for selected models.

Evaluation and application of an algorithm for atmospheric profiling continuity from Aqua to Suomi-NPP

NASA Astrophysics Data System (ADS)

Lipton, A.; Moncet, J. L.; Lynch, R.; Payne, V.; Alvarado, M. J.

2016-12-01

We will present results from an algorithm that is being developed to produce climate-quality atmospheric profiling earth system data records (ESDRs) for application to data from hyperspectral sounding instruments, including the Atmospheric InfraRed Sounder (AIRS) on EOS Aqua and the Cross-track Infrared Sounder (CrIS) on Suomi-NPP, along with their companion microwave sounders, AMSU and ATMS, respectively. The ESDR algorithm uses an optimal estimation approach and the implementation has a flexible, modular software structure to support experimentation and collaboration. Data record continuity benefits from the fact that the same algorithm can be applied to different sensors, simply by providing suitable configuration and data files. For analysis of satellite profiles over multi-decade periods, a concern is that the algorithm could respond inadequately to climate change if it uses a static background as a retrieval constraint, leading to retrievals that underestimate secular changes over extended periods of time and become biased toward an outdated climatology. We assessed the ability of our algorithm to respond appropriately to changes in temperature and water vapor profiles associated with climate change and, in particular, on the impact of using a climatological background in retrievals when the climatology is not static. We simulated a scenario wherein our algorithm processes 30 years of data from CrIS and ATMS (CrIMSS) with a static background based on data from the start of the 30-year period. We performed simulations using products from Coupled Model Intercomparison Project 5 (CMIP5), and in particular the "representative concentration pathways" midrange emissions (RCP4.5) scenario from the GISS-E2-R model. We will present results indicating that regularization using empirical orthogonal functions (EOFs) from a 30-year outdated covariance had a negligible effect on results. For temperature, the secular change is represented with high fidelity with the CrIMSS retrievals. For water vapor, an outdated background adds distortion to the secular moistening trend in the troposphere only above 300 mb, where the sensor information content is less than at lower levels. We will also present results illustrating the consistency between retrievals from near-simultaneous AIRS and CrIMSS measurements.

Predicting the Extent of Summer Sea Ice in the Arctic

NASA Astrophysics Data System (ADS)

Rigor, I. G.; Wallace, J. M.

2003-12-01

The summers of 1998 and 2002 had the least sea ice extent (SIE) in the Arctic. These observations seem to agree with the trends noted by Parkinson, et al. (1999, hereafter P99) for the period 1979-1997, but the spatial pattern of these recent decreases in summer SIE were different. The summer trends shown by P99, exhibit large decreases in SIE primarily in the East Siberian Sea (ESS), while the decreases observed during 1998 and 2002 were much larger in the Beaufort and Chukchi seas (BCS). We now show that the trends for the period 1979 - 2002 are much smaller in the ESS than the trends shown by P99, and the largest decreasing trends have shifted from the ESS to the BCS. Rigor, et al. (2002) showed that the changes in SIE that P99 noted were driven by changes in atmospheric circulation related to the phase of the prior winter Arctic Oscillation (AO, Thompson and Wallace, 1998) index. Given that the latest trends in SIE are different than those shown by P99, one could ask whether the affect of the AO on sea ice noted by Rigor, et al. (2002) has also changed, and whether some large scale climate modes other than the AO has influenced the climate of the Arctic Ocean more? To answer these questions, we applied Empirical Orthogonal Function (EOF) analysis on the September SIE data from microwave satellites, and found that the first two modes SIE were most highly correlated to the prior winter AO, and the AO index of the summer months just prior to each September. These modes explain more than 45% of the variance in SIE, and show that the influence of the winter and summer AO dominates Arctic climate from 1979 - 2002. Using data from the International Arctic Buoy Programme and the National Centers for Environmental Prediction, we will show that the changes in sea ice extent are primarily driven by dynamic changes in sea ice thickness and discuss the implications for predicting summer SIE.

Comparative study of the venoms from three species of bees: effects on heart activity and blood.

PubMed

Hussein, A A; Nabil, Z I; Zalat, S M; Rakha, M K

2001-11-01

Crude venoms from three highly evolved aculeate species: Apis mellifera (highly social bees), Bombus morrisoni (eusocial bees), and Anthophora pauperata (solitary bees), were used for conducting this study to compare the effects of honey bee, bumble bee, and solitary bee venom on toad cardiac muscle activity. In addition, these venoms were tested on rat whole blood in order to determine their ability to induce red blood cell haemolysis. The main toxic effects on isolated toad heart were monitored by ECG after perfusion with different concentrations of each bee venom, and are represented as a decrease in the heart rate (HR) accompanied by an elongation in the P-R interval. A gradual and progressive increase in R-wave amplitude was also noted. Several electrocardiographic changes were noted 5-30 min after envenomation with any of the bee venoms. The mechanism of action of the three bee venoms was determined by direct application of atropine, nicotine, or verapamil to the isolated toad hearts. Comparison of the three venoms revealed that Anthophora pauperata venom is the most effective venom in inducing bradycardia, and it has the strongest negative dromotropic effect. Apis mellifera venom demonstrates the most positive inotropic effect of the three venoms. The effects of bee venom on the blood indices of erythrocyte osmotic fragility (EOF) and plasma albumin levels were studied after incubation of rat blood with each venom. It was noticed that RBCs decreased while Hb content, HCT, MCV, MCH, and MCHC increased, although this change did fluctuate and was not significant. A nonsignificant decrease in EOF was noted after 60 min with any of the venoms used. Incubation of rat whole blood with 1 microg/ml of any of the bee venom solutions revealed a highly significant decrease in plasma albumin levels. It can be concluded that venoms from the three species of bees we tested have negative chronotropic and dromotropic effects on isolated toad heart, with Anthophora pauperata being the most potent. In addition, the venoms have positive inotropic effects withApis mellifera being the most potent. The nonsignificant effects of venom on blood profiles and erythrocyte osmotic fragility, combined with the significant decrease in plasma albumin level suggest a protective effect of plasma albumin against bee venom induced toxicity to erythrocytes.

Accounting for observational uncertainties in the evaluation of low latitude turbulent air-sea fluxes simulated in a suite of IPSL model versions

NASA Astrophysics Data System (ADS)

Servonnat, Jerome; Braconnot, Pascale; Gainusa-Bogdan, Alina

2015-04-01

Turbulent momentum and heat (sensible and latent) fluxes at the air-sea interface are key components of the whole energetic of the Earth's climate and their good representation in climate models is of prime importance. In this work, we use the methodology developed by Braconnot & Frankignoul (1993) to perform a Hotelling T2 test on spatio-temporal fields (annual cycles). This statistic provides a quantitative measure accounting for an estimate of the observational uncertainty for the evaluation of low-latitude turbulent air-sea fluxes in a suite of IPSL model versions. The spread within the observational ensemble of turbulent flux data products assembled by Gainusa-Bogdan et al (submitted) is used as an estimate of the observational uncertainty for the different turbulent fluxes. The methodology holds on a selection of a small number of dominating variability patterns (EOFs) that are common to both the model and the observations for the comparison. Consequently it focuses on the large-scale variability patterns and avoids the possibly noisy smaller scales. The results show that different versions of the IPSL couple model share common large scale model biases, but also that there the skill on sea surface temperature is not necessarily directly related to the skill in the representation of the different turbulent fluxes. Despite the large error bars on the observations the test clearly distinguish the different merits of the different model version. The analyses of the common EOF patterns and related time series provide guidance on the major differences with the observations. This work is a first attempt to use such statistic on the evaluation of the spatio-temporal variability of the turbulent fluxes, accounting for an observational uncertainty, and represents an efficient tool for systematic evaluation of simulated air-seafluxes, considering both the fluxes and the related atmospheric variables. References Braconnot, P., and C. Frankignoul (1993), Testing Model Simulations of the Thermocline Depth Variability in the Tropical Atlantic from 1982 through 1984, J. Phys. Oceanogr., 23(4), 626-647 Gainusa-Bogdan A., Braconnot P. and Servonnat J. (submitted), Using an ensemble data set of turbulent air-sea fluxes to evaluate the IPSL climate model in tropical regions, Journal of Geophysical Research Atmosphere, 2014JD022985

Gravitational Signal of Mass Redistribution Due to Interannual Meteorological Oscillations in Atmosphere and Ocean

NASA Technical Reports Server (NTRS)

Chao, B. F.; Au, A. Y.; Johnson, T.; Smith, David E. (Technical Monitor)

2001-01-01

Interannual meteorological oscillations (ENSO, QBO, NAO, etc.) have demonstrable influences on Earth's rotation. Here we study their effects on global gravitational field, whose temporal variations are being studied using SLR (satellite laser ranging) data and in anticipation of the new space mission GRACE. The meteorological oscillation modes are identified using the EOF (empirical orthogonal function)/PC (principal component) decomposition of surface fields (in which we take care of issues associated with the area-weighting and non-zero mean). We examine two fields, one for the global surface pressure field for the atmosphere obtained from the NCEP reanalysis (for the past 40 years), one for the surface topography field for the ocean from the Topex/Poseidon (T/P) data (for the past 8 years). We use monthly maps, and remove the mean-monthly ("climatology") values from each grid point, hence focusing only on non-seasonal signals. The T/P data were first subject to a steric correction where the steric contribution to the ocean surface topography was removed according to output of the numerical POCM model. The respective atmospheric and oceanic contributions to the gravitational variation, in terms of harmonic Stokes coefficients, are then combined mode-by-mode. Since the T/P data already contain the oceanic response to overlying atmospheric pressure, no regards to the inverted-barometer behavior for the ocean need be considered. Results for the lowest-degree Stokes coefficients can then be compared with space geodetic observations including the Earth's rotation and the SLR data mentioned above, to identify the importance of each meteorological oscillations in gravitational variation signals.

GOME-2 Tropospheric Ozone Profile Retrievals from Joint UV/Visible Measurement

NASA Astrophysics Data System (ADS)

Liu, X.; Zoogman, P.; Chance, K.; Cai, Z.; Nowlan, C. R.; Huang, G.; Gonzalez Abad, G.

2016-12-01

It has been shown from sensitivity studies that adding visible measurements in the Chappuis ozone band to UV measurements in the Hartley/Huggins ozone bands can significantly enhance retrieval sensitivity to lower tropospheric ozone from backscattered solar radiances due to deeper photon penetration in the visible to the surface than in the ultraviolet. The first NASA EVI (Earth Venture Instrument) TEMPO (Tropospheric Emissions: Monitoring of Pollution) instrument is being developed to measure backscattered solar radiation in two channels ( 290-490 and 540-740 nm) and make atmospheric pollution measurements over North America from the Geostationary orbit. However, this retrieval enhancement has yet to be demonstrated from existing measurements due to the weak ozone absorption in the visible and strong interferences from surface reflectance and aerosols and the requirement of accurate radiometric calibration across different spectral channels. We present GOME-2 retrievals from joint UV/visible measurements using the SAO ozone profile retrieval algorithm, to directly explore the retrieval improvement in lower tropospheric ozone from additional visible measurements. To reduce the retrieval interference from surface reflectance, we add characterization of surface spectral reflectance in the visible based on combining EOFs (Empirical Orthogonal Functions) derived from ASTER and other surface reflectance spectra with MODIS BRDF climatology into the ozone profile algorithm. The impacts of various types of aerosols and surface BRDF on the retrievals will be investigated. In addition, we will also perform empirical radiometric calibration of the GOME-2 data based on radiative transfer simulations. We will evaluate the retrieval improvement of joint UV/visible retrieval over the UV retrieval based on fitting quality and validation against ozonesonde observations.

Chemistry and Transport in a Multi-Dimensional Model

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

2004-01-01

Our work has two primary scientific goals, the interannual variability (IAV) of stratospheric ozone and the hydrological cycle of the upper troposphere and lower stratosphere. Our efforts are aimed at integrating new information obtained by spacecraft and aircraft measurements to achieve a better understanding of the chemical and dynamical processes that are needed for realistic evaluations of human impact on the global environment. A primary motivation for studying the ozone layer is to separate the anthropogenic perturbations of the ozone layer from natural variability. Using the recently available merged ozone data (MOD), we have carried out an empirical orthogonal function EOF) study of the temporal and spatial patterns of the IAV of total column ozone in the tropics. The outstanding problem about water in the stratosphere is its secular increase in the last few decades. The Caltech/PL multi-dimensional chemical transport model (CTM) photochemical model is used to simulate the processes that control the water vapor and its isotopic composition in the stratosphere. Datasets we will use for comparison with model results include those obtained by the Total Ozone Mapping Spectrometer (TOMS), the Solar Backscatter Ultraviolet (SBUV and SBUV/2), Stratosphere Aerosol and Gas Experiment (SAGE I and II), the Halogen Occultation Experiment (HALOE), the Atmospheric Trace Molecular Spectroscopy (ATMOS) and those soon to be obtained by the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) mission. The focus of the investigations is the exchange between the stratosphere and the troposphere, and between the troposphere and the biosphere.

Surface temperature patterns in complex terrain: Daily variations and long-term change in the central Sierra Nevada, California

USGS Publications Warehouse

Lundquist, J.D.; Cayan, D.R.

2007-01-01

A realistic description of how temperatures vary with elevation is crucial for ecosystem studies and for models of basin-scale snowmelt and spring streamflow. This paper explores surface temperature variability using temperature data from an array of 37 sensors, called the Yosemite network, which traverses both slopes of the Sierra Nevada in the vicinity of Yosemite National Park, California. These data indicate that a simple lapse rate is often a poor description of the spatial temperature structure. Rather, the spatial pattern of temperature over the Yosemite network varies considerably with synoptic conditions. Empirical orthogonal functions (EOFs) were used to identify the dominant spatial temperature patterns and how they vary in time. Temporal variations of these surface temperature patterns were correlated with large-scale weather conditions, as described by National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis data. Regression equations were used to downscale larger-scale weather parameters, such as Reanalysis winds and pressure, to the surface temperature structure over the Yosemite network. These relationships demonstrate that strong westerly winds are associated with relatively warmer temperatures on the east slope and cooler temperatures on the west slope of the Sierra, and weaker westerly winds are associated with the opposite pattern. Reanalysis data from 1948 to 2005 indicate weakening westerlies over this time period, a trend leading to relatively cooler temperatures on the east slope over decadal timescale's. This trend also appears in long-term observations and demonstrates the need to consider topographic effects when examining long-term changes in mountain regions. Copyright 2007 by the American Geophysical Union.

Nonlinear Dynamical Modes as a Basis for Short-Term Forecast of Climate Variability

NASA Astrophysics Data System (ADS)

Feigin, A. M.; Mukhin, D.; Gavrilov, A.; Seleznev, A.; Loskutov, E.

2017-12-01

We study abilities of data-driven stochastic models constructed by nonlinear dynamical decomposition of spatially distributed data to quantitative (short-term) forecast of climate characteristics. We compare two data processing techniques: (i) widely used empirical orthogonal function approach, and (ii) nonlinear dynamical modes (NDMs) framework [1,2]. We also make comparison of two kinds of the prognostic models: (i) traditional autoregression (linear) model and (ii) model in the form of random ("stochastic") nonlinear dynamical system [3]. We apply all combinations of the above-mentioned data mining techniques and kinds of models to short-term forecasts of climate indices based on sea surface temperature (SST) data. We use NOAA_ERSST_V4 dataset (monthly SST with space resolution 20 × 20) covering the tropical belt and starting from the year 1960. We demonstrate that NDM-based nonlinear model shows better prediction skill versus EOF-based linear and nonlinear models. Finally we discuss capability of NDM-based nonlinear model for long-term (decadal) prediction of climate variability. [1] D. Mukhin, A. Gavrilov, E. Loskutov , A.Feigin, J.Kurths, 2015: Principal nonlinear dynamical modes of climate variability, Scientific Reports, rep. 5, 15510; doi: 10.1038/srep15510. [2] Gavrilov, A., Mukhin, D., Loskutov, E., Volodin, E., Feigin, A., & Kurths, J., 2016: Method for reconstructing nonlinear modes with adaptive structure from multidimensional data. Chaos: An Interdisciplinary Journal of Nonlinear Science, 26(12), 123101. [3] Ya. Molkov, D. Mukhin, E. Loskutov, A. Feigin, 2012: Random dynamical models from time series. Phys. Rev. E, Vol. 85, n.3.

The Deep Meridional Overturning Circulation in the Indian Ocean Inferred from the GECCO Synthesis

NASA Astrophysics Data System (ADS)

Wang, W.; Koehl, A.; Stammer, D.

2012-04-01

The meridional overturning circulation in the Indian Ocean and its temporal variability in the GECCO ocean synthesis are being investigated. An analysis of the integrated circulation in different layers suggests that, on time average, 2.1 Sv enter the Indian Ocean in the bottom layer (>3200m) from the south and that 12.3 Sv leave the Indian Ocean in the upper and intermediate layers (<1500m), composed of the up-welled bottom layer inflow water, augmented by 9.6 Sv Indonesian Throughflow (ITF) water. The GECCO time-mean results differ significantly from those obtained by box inverse models, which, being based on individual hydrographic sections, are susceptible to aliasing. The GECCO solution has a large seasonal variation in its meridional overturning caused by the seasonal reversal of monsoon-related wind stress forcing. Associated seasonal variations of the deep meridional overturning range from -7 Sv in boreal winter to 3 Sv in summer. In addition, the upper and bottom transports across 34°S section show pronounced interannual variability with roughly biennial variations superimposed by strong anomalies during each La Niña phase as well as the ITF, which mainly affect the upper layer transports. On decadal and longer timescale, the meridional overturning variability as well as long-term trends differ before and after 1980. Notably, our analysis shows a rather stable trend for the period 1960-1979 and significant changes in the upper and bottom layer for the period 1980-2001. By means of a multivariate EOF analysis, the importance of Ekman dynamics as driving forces of the deep meridional overturning of the Indian Ocean on the interannual timescale is highlighted. The leading modes of the zonal and meridional wind stress favour a basin-wide meridional overturning mode via Ekman upwelling or downwelling mostly in the central and eastern Indian Ocean. Moreover, tropical zonal wind stress along the equator and alongshore wind stress off the Sumatra-Java coast contributes to evolution of IOD events.

Monitoring Global Sea Level: Eustatic Variations, Local Variations, and Solid Earth Effects

NASA Technical Reports Server (NTRS)

Davis, James L.

2000-01-01

Project BIFROST (Baseline Inferences for Fennoscandian Rebound Observations. Sea-level and Tectonics) combines networks of continuously operating CPS receivers in Sweden and Finland to measure ongoing crustal deformation due to glacial isostatic adjustment, (CIA). We present an analysis of data collected in the years 1993-1998. We compare the CPS determinations of three-dimensional crustal motion to predictions calculated using the high resolution Fennoscandian deglaciation model recently proposed by Lambeck et al. We find that the the maximum observed uplift rate (approx. 10 mm/ yr) and the maximum predicted uplift rate agree to better than 1 mm/ yr. The patterns of uplift also agree quite well, although differences are discernible. The chi(exp 2) difference between predicted and GPS-observed radial rates is reduced by a factor of 5-6 compared to that for the "null" (no uplift) model, depending on whether a mean difference is first removed. The north components of velocity agree at about the same relative level. whereas the agreement for the east components is worse, a problem possibly related to the lack of bias fixing. We have also compared the values for the observed radial deformation rates to those based on sea-level rates from Baltic tide gauges. The weighted RMS difference between CPS and tide-gauge rates (after removing a mean) is 0.6 mm/ yr, giving an indication of the combined accuracy of the CPS and tide-gauge measurement systems. Spectral analysis of the time series of position estimates yields spectral indices in the range -1 to -2. An EOF analysis indicates, however, that much of this power is correlated among the sites. The correlation appears to be regional and falls off only slightly with distance. Some of this correlated noise is associated with snow accumulation on the antennas or, for those antennas with radomes, on the radomes. This problem has caused us to modify the radomes used several times, leading to one of our more significant sources of uncertainty.

Department of the Air Force Supporting Data for Fiscal Year 1981, Budget Estimates Submitted to Congress January 1980, Descriptive Summaries, Research, Development, Test and Evaluation

DTIC Science & Technology

1980-01-01

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Preparation of polyhedral oligomeric silsesquioxane based hybrid monoliths by ring-opening polymerization for capillary LC and CEC.

PubMed

Lin, Hui; Zhang, Zhenbin; Dong, Jing; Liu, Zhongshan; Ou, Junjie; Zou, Hanfa

2013-09-01

A new organic-inorganic hybrid monolith was prepared by the ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS) with 1,4-butanediamine (BDA) using 1-propanol, 1,4-butanediol, and PEG 10,000 as a porogenic system. Benefiting from the moderate phase separation process, the resulting poly(POSS-co-BDA) hybrid monolith possessed a uniform microstructure and exhibited excellent performance in chromatographic applications. Neutral, acidic, and basic compounds were successfully separated on the hybrid monolith in capillary LC (cLC), and high column efficiencies were achieved in all of the separations. In addition, as the amino groups could generate a strong EOF, the hybrid monolith was also applied in CEC for the separation of neutral and polar compounds, and a satisfactory performance was obtained. These results demonstrate that the poly(POSS-co-BDA) hybrid monolith is a good separation media in chromatographic separations of various types of compounds by both cLC and CEC. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enantiomeric separation by capillary electrochromatography on a sulfated poly β-cyclodextrin modified silica-based monolith.

PubMed

Yuan, Ruijuan; Wang, Yan; Ding, Guosheng

2010-01-01

A sulfated poly β-cyclodextrin (SPCD) modified silica-based monolithic column was prepared for enantiomeric separation. First, 2-hydroxy-3-allyloxy-propyl-β-cyclodextrin (allyl-β-CD) was bonded onto a bifunctional reagent 3-(methacryloxy)propyltriethoxysilane (γ-MAPS) modified silica-based monolith through radical polymerization; the column was then sulfated with chlorosulfonic acid. The SPCD chiral stationary phase resolved the boring problem associated with desalting when sulfated CDs were synthesized to act as chiral additives. The inorganic salt in the column introduced during the sulfating process could be easily removed by washing the column with water for some time. Chiral compounds investigated were successfully resolved into their enantiomers on the SPCD modified monolith in the capillary electrochromatography (CEC) mode. Due to the existence of the -SO(3)H group, electrosmotic flow (EOF) was obviously increased, and all of the separations could be carried out in 20 min with only a minor loss in the column efficiency and resolution.

Two-Dimensional Fluidization of Nanomaterials via Biomimetic Membranes towards Assisted Self Assembly

NASA Astrophysics Data System (ADS)

Kelly, Kathleen

Materials that take advantage of the exceptional properties of nano-meter sized aggregates of atoms are poised to play an important role in future technologies. Prime examples for such nano-materials that have an extremely large surface to volume ratio and thus are physically determined by surface related effects are quantum dots (qdots) and carbon nanotubes (CNTs). The production of such manmade nano-objects has by now become routine and even commercialized. However, the controlled assembly of individual nano-sized building blocks into larger structures of higher geometric and functional complexity has proven to be much more challenging. Yet, this is exactly what is required for many applications that have transformative potential for new technologies. If the tedious procedure to sequentially position individual nano-objects is to be forgone, the assembly of such objects into larger structures needs to be implicitly encoded and many ways to bestow such self-assembly abilities onto nano objects are being developed. Yet, as overall size and complexity of such self-assembled structures increases, kinetic and geometric frustration begin to prevent the system to achieve the desired configuration. In nature, this problem is solved by relying on guided or forced variants of the self-assembly approach. To translate such concepts into the realm of man-made nano-technology, ways to dynamically manipulate nano-materials need to be devised. Thus, in the first part of this work, I provide a proof of concept that supported lipid bilayers (SLBs) that exhibit free lateral diffusion of their constituents can be utilized as a two-dimensional platform for active nano-material manipulation. We used streptavidin coated quantum dots (Q-dots) as a model nano-building-block. Q-dots are 0-dimensional nanomaterials engineered to be fluorescent based solely on their diameter making visualization convenient. Biotinylated lipids were used to tether Q-dots to a SLB and we observed that the 2-dimensional fluidity of the bilayer was translated to the quantum dots as they freely diffused. The quantum dots were visualized using wide-field fluorescent microscopy and single particle tracking techniques were employed to analyze their dynamic behavior. Next, an electric field was applied to the system to induce electroosmotic flow (EOF) which creates a bulk flow of the buffer solution. The quantum dots were again tracked and ballistic motion was observed in the particle tracks due to the electroosmosis in the system. This proved that SLBs could be used as a two-dimensional fluid platform for nanomaterials and electroosmosis can be used to manipulate the motion of the Q-dots once they are tethered to the membrane. Next, we set out to employ the same technique to carbon nanotubes (CNTs), which are known for their highly versatile mechanical and electrical properties. However, carbon nanotubes are extremely hydrophobic and tend to aggregate in aqueous solutions which negatively impacts the viability of tethering the CNTs to the bilayer, fluorescently staining and then imaging them. First, we had to solubilize the CNTs such that they were monodisperse and characterize the CNT-detergent solutions. We were able to create monodisperse solutions of CNTs such that the detergent levels were low enough that the integrity of the bilayer was intact. We were also able to fluorescently label the CNTs in order to visualize them, and tether them to a SLB using a peptide sequence. Future directions of this project would include employing EOF to mobilize the CNTs and use a more sophisticated single particle tracking software to track individual CNTs and analyze their motion.

A preliminary experiment for the long-term regional reanalysis over Japan assimilating conventional observations with NHM-LETKF

NASA Astrophysics Data System (ADS)

Fukui, Shin; Iwasaki, Toshiki; Saito, Kazuo; Seko, Hiromu; Kunii, Masaru

2016-04-01

Several long-term global reanalyses have been produced by major operational centres and have contributed to the advance of weather and climate researches considerably. Although the horizontal resolutions of these global reanalyses are getting higher partly due to the development of computing technology, they are still too coarse to reproduce local circulations and precipitation realistically. To solve this problem, dynamical downscaling is often employed. However, the forcing from lateral boundaries only cannot necessarily control the inner fields especially in long-term dynamical downscaling. Regional reanalysis is expected to overcome the difficulty. To maintain the long-term consistency of the analysis quality, it is better to assimilate only the conventional observations that are available in long period. To confirm the effectiveness of the regional reanalysis, some assimilation experiments are performed. In the experiments, only conventional observations (SYNOP, SHIP, BUOY, TEMP, PILOT, TC-Bogus) are assimilated with the NHM-LETKF system, which consists of the nonhydrostatic model (NHM) of the Japan Meteorological Agency (JMA) and the local ensemble transform Kalman filter (LETKF). The horizontal resolution is 25 km and the domain covers Japan and its surroundings. Japanese 55-year reanalysis (JRA-55) is adopted as the initial and lateral boundary conditions for the NHM-LETKF forecast-analysis cycles. The ensemble size is 10. The experimental period is August 2014 as a representative of warm season for the region. The results are verified against the JMA's operational Meso-scale Analysis, which is produced with assimilating observation data including various remote sensing observations using a 4D-Var scheme, and compared with those of the simple dynamical downscaling experiment without data assimilation. Effects of implementation of lateral boundary perturbations derived from an EOF analysis of JRA-55 over the targeted domain are also examined. The comparison proposes that the assimilation system can reproduce more accurate fields than dynamical downscaling. The implementation of the lateral boundary perturbations implies that the perturbations contribute to providing more appropriate ensemble spreads, though the perturbations are not necessarily consistent to those of the inner fields given by NHM-LETKF.

Single-step CE for miniaturized and easy-to-use system.

PubMed

Ono, Koichi; Kaneda, Shohei; Fujii, Teruo

2013-03-01

We developed a novel single-step capillary electrophoresis (SSCE) scheme for miniaturized and easy to use system by using a microchannel chip, which was made from the hydrophilic material polymethyl methacrylate (PMMA), equipped with a capillary stop valve. Taking the surface tension property of liquids into consideration, the capillary effect was used to introduce liquids and control capillary stop valves in a partial barrier structure in the wall of the microchannel. Through the combined action of stop valves and air vents, both sample plug formation for electrophoresis and sample injection into a separation channel were successfully performed in a single step. To optimize SSCE, different stop valve structures were evaluated using actual microchannel chips and the finite element method with the level set method. A partial barrier structure at the bottom of the channel functioned efficiently as a stop valve. The stability of stop valve was confirmed by a shock test, which was performed by dropping the microchannel chip to a floor. Sample plug deformation could be reduced by minimizing the size of the side partial barrier. By dissolving hydroxyl ethyl cellulose and using it as the sample solution, the EOF and adsorption of the sample into the PMMA microchannel were successfully reduced. Using this method, a 100-bp DNA ladder was concentrated; good separation was observed within 1 min. At a separation length of 5 mm, the signal was approximately 20-fold higher than a signal of original sample solution by field-amplified sample stacking effect. All operations, including liquid introduction and sample separation, can be completed within 2 min by using the SSCE scheme. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrokinetically driven active micro-mixers utilizing zeta potential variation induced by field effect

NASA Astrophysics Data System (ADS)

Lee, Chia-Yen; Lee, Gwo-Bin; Fu, Lung-Ming; Lee, Kuo-Hoong; Yang, Ruey-Jen

2004-10-01

This paper presents a new electrokinetically driven active micro-mixer which uses localized capacitance effects to induce zeta potential variations along the surface of silica-based microchannels. The mixer is fabricated by etching bulk flow and shielding electrode channels into glass substrates and then depositing Au/Cr thin films within the latter to form capacitor electrodes, which establish localized zeta potential variations near the electrical double layer (EDL) region of the electroosmotic flow (EOF) within the microchannels. The potential variations induce flow velocity changes within a homogeneous fluid and a rapid mixing effect if an alternating electric field is provided. The current experimental data confirm that the fluid velocity can be actively controlled by using the capacitance effect of the buried shielding electrodes to vary the zeta potential along the channel walls. While compared with commonly used planar electrodes across the microchannels, the buried shielding electrodes prevent current leakage caused by bad bonding and allow direct optical observation during operation. It also shows that the buried shielding electrodes can significantly induce the field effect, resulting in higher variations of zeta potential. Computational fluid dynamic simulations are also used to study the fluid characteristics of the developed active mixers. The numerical and experimental results demonstrate that the developed microfluidic device permits a high degree of control over the fluid flow and an efficient mixing effect. Moreover, the developed device could be used as a pumping device as well. The development of the active electrokinetically driven micro-mixer could be crucial for micro-total-analysis-systems.

Multi-Proxy Reconstructions of Northeast Pacific Decadal Variability from Bivalve Mollusks and Trees

NASA Astrophysics Data System (ADS)

Black, B.; Griffin, D.

2017-12-01

Decadal-scale climate variability in the Northeast Pacific Ocean profoundly influences fisheries production, forest growth, wildfire, drought, and snowpack in western North America. However, there remains considerable and long-standing uncertainly in its behavior prior to AD 1900 and the extent to which 20th century dynamics are atypical in a multi-centennial context. Here, we target the leading EOF of SST in the northeastern Pacific (ARCSST) as an index of Pacific Decadal Variability, which has been dynamically linked to sea level pressure and unlike the Pacific Decadal Oscillation Index, retains a linear warming trend. The ARCSST reconstruction is generated from a broad network of target-sensitive North American tree-ring data standardized using signal-free detrending to preserve lower frequency signals common to the original data. In a preliminary analysis, the mean of the approximately 50 chronologies that significantly (p < 0.01) correlate to the target variable explain 60% of the variance in cool-season ARCSST. Reconstruction skill is independently verified by three marine bivalve (Pacific geoduck; Panopea generosa) chronologies, the mean of which accounts for over 50% of the reconstruction variance over the common 1870-1900 interval. The nested reconstruction spans over 500 years and indicates that i) PDV is dominated by pentadecadal cycles, ii) century-long quiescent periods can occur, iii) 20th century regime shifts are typical, but iv) late 20th century warming is atypical in the longer-term context. Moreover, the reconstruction closely tracks paleofisheries datasets, particularly northern anchovy (Engraulis mordax) abundance inferred from scale deposition rates in the Santa Barbara Basin.

The Role of African Easterly Wave on Dust Transport and the Interaction Between Saharan Dust Layer and Atlantic ITCZ During Boreal Summer

NASA Technical Reports Server (NTRS)

Kim, Kyu-Myong; Lau, William K-M

2011-01-01

Saharan dust outbreaks not only transport large amount of dust to the northern Atlantic Ocean, but also alter African easterly jet and wave activities along the jet by changing north-south temperature gradient. Recent modeling and observational studies show that during periods of enhance outbreaks, rainfall on the northern part of ITCZ increases in conjunction with a northward shift of ITCZ toward the dust layer. In this paper, we study the radiative forcing of Saharan dust and its interactions with the Atlantic Inter-tropical Convergence Zone (ITCZ), through African easterly waves (AEW), African easterly jet (AEJ), using the Terra/Aqua observations as well as MERRA data. Using band pass filtered EOF analysis, we find that African easterly waves propagating westward along two principal tracks, centered at 15-25N and 5-10N respectively. The easterly waves in the northern track are slower, with propagation speed of 9 ms-1, and highly correlated with major dust outbreak over North Africa. On the other hand, easterly waves along the southern track are faster with propagating speed of 10 ms-1, and are closely tied to rainfall/cloud variations along the Atlantic ITCZ. Dust transport along the southern track leads rainfall/cloud anomalies in the same region by one or two days, suggesting the southern tracks of dust outbreak are regions of strong interaction between Saharan dust layer and Atlantic ITCZ. Possible linkage between two tracks of easterly waves, as well as the long-term change of easterly wave activities and dust outbreaks, are also discussed.

Changes in atmospheric circulation between solar maximum and minimum conditions in winter and summer

NASA Astrophysics Data System (ADS)

Lee, Jae Nyung

2008-10-01

Statistically significant climate responses to the solar variability are found in Northern Annular Mode (NAM) and in the tropical circulation. This study is based on the statistical analysis of numerical simulations with ModelE version of the chemistry coupled Goddard Institute for Space Studies (GISS) general circulation model (GCM) and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The low frequency large scale variability of the winter and summer circulation is described by the NAM, the leading Empirical Orthogonal Function (EOF) of geopotential heights. The newly defined seasonal annular modes and its dynamical significance in the stratosphere and troposphere in the GISS ModelE is shown and compared with those in the NCEP/NCAR reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both the model and observation suggests that the summer stratosphere is more "summer-like" when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum variability over the Asian monsoon region. The corresponding EOF in ModelE has a qualitatively similar structure but with less variability in the Asian monsoon region which is displaced eastward of its observed position. In both the NCEP/NCAR reanalysis and the GISS GCM, the negative anomalies associated with the NAM in the Euro-Atlantic and Aleutian island regions are enhanced in the solar minimum conditions, though the results are not statistically significant. The difference of the downward propagation of NAM between solar maximum and solar minimum is shown with the NCEP/NCAR reanalysis. For the winter NAM, a much greater fraction of stratospheric circulation perturbations penetrate to the surface in solar maximum conditions than in minimum conditions. This difference is more striking when the zonal wind direction in the tropics is from the west: when equatorial 50 hPa winds are from the west, no stratospheric signals reach the surface under solar minimum conditions, while over 50 percent reach the surface under solar maximum conditions. This work also studies the response of the tropical circulation to the solar forcing in combination with different atmospheric compositions and with different ocean modules. Four model experiments have been designed to investigate the role of solar forcing in the tropical circulation: one with the present day (PD) greenhouse gases and aerosol conditions, one with the preindustrial (PI) conditions, one with the doubled minimum solar forcing, and finally one with the hybrid-isopycnic ocean model (HYCOM). The response patterns in the tropical humidity and in the vertical motion due to solar forcing are season dependent and spatially heterogeneous. The tropical humidity response from the model experiments are compared with the corresponding differences obtained from the NCEP/NCAR reanalysis with all years and with non-ENSO years. Both the model and the reanalysis consistently show that the specific humidity is significantly greater in the convective region in solar maximum compared to solar minimum for January and July. The column integrated humidity in all the model experiments with different composition, different solar forcing, and different ocean module, increased with solar forcing in the tropical band over the Atlantic sector in both seasons. The model's humidity response pattern is generally consistent with the paleoclimate records indicating increased precipitation near the equator that decreases at subtropical to middle latitudes with increased solar output. The differences in the zonally averaged vertical velocities indicate that the ascending branch of the Hadley cell is enhanced and shifted northward, and that the descending branch is weakened and shifted northward in the solar MAX simulation in January. The downward branch of the Hadley cell is strengthened in MAX in July. A possible link of climate response in midlatitudes to solar forcing is also presented by showing changes in zonal mean wind, changes in temperature gradient, and changes in E-P flux.

Benchmarking in a differentially heated rotating annulus experiment: Multiple equilibria in the light of laboratory experiments and simulations

NASA Astrophysics Data System (ADS)

Vincze, Miklos; Harlander, Uwe; Borchert, Sebastian; Achatz, Ulrich; Baumann, Martin; Egbers, Christoph; Fröhlich, Jochen; Hertel, Claudia; Heuveline, Vincent; Hickel, Stefan; von Larcher, Thomas; Remmler, Sebastian

2014-05-01

In the framework of the German Science Foundation's (DFG) priority program 'MetStröm' various laboratory experiments have been carried out in a differentially heated rotating annulus configuration in order to test, validate and tune numerical methods to be used for modeling large-scale atmospheric processes. This classic experimental set-up is well known since the late 1940s and is a widely studied minimal model of the general mid-latitude atmospheric circulation. The two most relevant factors of cyclogenesis, namely rotation and meridional temperature gradient are quite well captured in this simple arrangement. The tabletop-size rotating tank is divided into three sections by coaxial cylindrical sidewalls. The innermost section is cooled whereas the outermost annular cavity is heated, therefore the working fluid (de-ionized water) in the middle annular section experiences differential heat flow, which imposes thermal (density) stratification on the fluid. At high enough rotation rates the isothermal surfaces tilt, leading to baroclinic instability. The extra potential energy stored in this unstable configuration is then converted into kinetic energy, exciting drifting wave patterns of temperature and momentum anomalies. The signatures of these baroclinic waves at the free water surface have been analysed via infrared thermography in a wide range of rotation rates (keeping the radial temperature difference constant) and under different initial conditions (namely, initial spin-up and "spin-down"). Paralelly to the laboratory simulations of BTU Cottbus-Senftenberg, five other groups from the MetStröm collaboration have conducted simulations in the same parameter regime using different numerical approaches and solvers, and applying different initial conditions and perturbations for stability analysis. The obtained baroclinic wave patterns have been evaluated via determining and comparing their Empirical Orthogonal Functions (EOFs), drift rates and dominant wave modes. Thus certain "benchmarks" have been created that can later be used as test cases for atmospheric numerical model validation. Both in the experiments and in the numerics multiple equilibrium states have been observed in the form of hysteretic behavior depending on the initial conditions. The precise quantification of these state and wave mode transitions may shed light to some aspects of the basic underlying dynamics of the baroclinic annulus configuration, still to be understood.

The new Cloud Dynamics and Radiation Database algorithms for AMSR2 and GMI: exploitation of the GPM observational database for operational applications

NASA Astrophysics Data System (ADS)

Cinzia Marra, Anna; Casella, Daniele; Martins Costa do Amaral, Lia; Sanò, Paolo; Dietrich, Stefano; Panegrossi, Giulia

2017-04-01

Two new precipitation retrieval algorithms for the Advanced Microwave Scanning Radiometer 2 (AMSR2) and for the GPM Microwave Imager (GMI) are presented. The algorithms are based on the Cloud Dynamics and Radiation Database (CDRD) Bayesian approach and represent an evolution of the previous version applied to Special Sensor Microwave Imager/Sounder (SSMIS) observations, and used operationally within the EUMETSAT Satellite Application Facility on support to Operational Hydrology and Water Management (H-SAF). These new products present as main innovation the use of an extended database entirely empirical, derived from coincident radar and radiometer observations from the NASA/JAXA Global Precipitation Measurement Core Observatory (GPM-CO) (Dual-frequency Precipitation Radar-DPR and GMI). The other new aspects are: 1) a new rain-no-rain screening approach; 2) the use of Empirical Orthogonal Functions (EOF) and Canonical Correlation Analysis (CCA) both in the screening approach, and in the Bayesian algorithm; 2) the use of new meteorological and environmental ancillary variables to categorize the database and mitigate the problem of non-uniqueness of the retrieval solution; 3) the development and implementations of specific modules for computational time minimization. The CDRD algorithms for AMSR2 and GMI are able to handle an extremely large observational database available from GPM-CO and provide the rainfall estimate with minimum latency, making them suitable for near-real time hydrological and operational applications. As far as CDRD for AMSR2, a verification study over Italy using ground-based radar data and over the MSG full disk area using coincident GPM-CO/AMSR2 observations has been carried out. Results show remarkable AMSR2 capabilities for rainfall rate (RR) retrieval over ocean (for RR > 0.25 mm/h), good capabilities over vegetated land (for RR > 1 mm/h), while for coastal areas the results are less certain. Comparisons with NASA GPM products, and with ground-based radar data, show that CDRD for AMSR2 is able to depict very well the areas of high precipitation over all surface types. Similarly, preliminary results of the application of CDRD for GMI are also shown and discussed, highlighting the advantage of the availability of high frequency channels (> 90 GHz) for precipitation retrieval over land and coastal areas.

Merging Multi-model CMIP5/PMIP3 Past-1000 Ensemble Simulations with Tree Ring Proxy Data by Optimal Interpolation Approach

NASA Astrophysics Data System (ADS)

Chen, Xin; Luo, Yong; Xing, Pei; Nie, Suping; Tian, Qinhua

2015-04-01

Two sets of gridded annual mean surface air temperature in past millennia over the Northern Hemisphere was constructed employing optimal interpolation (OI) method so as to merge the tree ring proxy records with the simulations from CMIP5 (the fifth phase of the Climate Model Intercomparison Project). Both the uncertainties in proxy reconstruction and model simulations can be taken into account applying OI algorithm. For better preservation of physical coordinated features and spatial-temporal completeness of climate variability in 7 copies of model results, we perform the Empirical Orthogonal Functions (EOF) analysis to truncate the ensemble mean field as the first guess (background field) for OI. 681 temperature sensitive tree-ring chronologies are collected and screened from International Tree Ring Data Bank (ITRDB) and Past Global Changes (PAGES-2k) project. Firstly, two methods (variance matching and linear regression) are employed to calibrate the tree ring chronologies with instrumental data (CRUTEM4v) individually. In addition, we also remove the bias of both the background field and proxy records relative to instrumental dataset. Secondly, time-varying background error covariance matrix (B) and static "observation" error covariance matrix (R) are calculated for OI frame. In our scheme, matrix B was calculated locally, and "observation" error covariance are partially considered in R matrix (the covariance value between the pairs of tree ring sites that are very close to each other would be counted), which is different from the traditional assumption that R matrix should be diagonal. Comparing our results, it turns out that regional averaged series are not sensitive to the selection for calibration methods. The Quantile-Quantile plots indicate regional climatologies based on both methods are tend to be more agreeable with regional reconstruction of PAGES-2k in 20th century warming period than in little ice age (LIA). Lager volcanic cooling response over Asia and Europe in context of recent millennium are detected in our datasets than that revealed in regional reconstruction from PAGES-2k network. Verification experiments have showed that the merging approach really reconcile the proxy data and model ensemble simulations in an optimal way (with smaller errors than both of them). Further research is needed to improve the error estimation on them.

Peak capacity and peak capacity per unit time in capillary and microchip zone electrophoresis.

PubMed

Foley, Joe P; Blackney, Donna M; Ennis, Erin J

2017-11-10

The origins of the peak capacity concept are described and the important contributions to the development of that concept in chromatography and electrophoresis are reviewed. Whereas numerous quantitative expressions have been reported for one- and two-dimensional separations, most are focused on chromatographic separations and few, if any, quantitative unbiased expressions have been developed for capillary or microchip zone electrophoresis. Making the common assumption that longitudinal diffusion is the predominant source of zone broadening in capillary electrophoresis, analytical expressions for the peak capacity are derived, first in terms of migration time, diffusion coefficient, migration distance, and desired resolution, and then in terms of the remaining underlying fundamental parameters (electric field, electroosmotic and electrophoretic mobilities) that determine the migration time. The latter expressions clearly illustrate the direct square root dependence of peak capacity on electric field and migration distance and the inverse square root dependence on solute diffusion coefficient. Conditions that result in a high peak capacity will result in a low peak capacity per unit time and vice-versa. For a given symmetrical range of relative electrophoretic mobilities for co- and counter-electroosmotic species (cations and anions), the peak capacity increases with the square root of the electric field even as the temporal window narrows considerably, resulting in a significant reduction in analysis time. Over a broad relative electrophoretic mobility interval [-0.9, 0.9], an approximately two-fold greater amount of peak capacity can be generated for counter-electroosmotic species although it takes about five-fold longer to do so, consistent with the well-known bias in migration time and resolving power for co- and counter-electroosmotic species. The optimum lower bound of the relative electrophoretic mobility interval [μ r,Z , μ r,A ] that provides the maximum peak capacity per unit time is a simple function of the upper bound, but its direct application is limited to samples with analytes whose electrophoretic mobilities can be varied independently of electroosmotic flow. For samples containing both co- and counter-electroosmotic ions whose electrophoretic mobilities cannot be easily manipulated, comparable levels of peak capacity and peak capacity per unit time for all ions can be obtained by adjusting the EOF to devote the same amount of time to the separation of each class of ions; this corresponds to μ r,Z =-0.5. Copyright © 2017 Elsevier B.V. All rights reserved.

Decadal Air-Sea Interaction in the North Atlantic Based on Observations and Modeling Results

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa

1998-01-01

The decadal, 12-14 year, cycle observed in the North Atlantic SST and tide gauge data was examined using the NCEP/NCAR reanalyses, COADS data and an ocean model simulation. Besides this decadal mode, a shorter, subdecadal period of about 8 years exists in tide gauge data north of 40N, in the subpolar SST and in the winter North Atlantic Oscillation (NAO) index and in subpolar winter heat flux values. The decadal cycle is a well separated mode in a singular spectrum analysis (SSA) for a time series of SST EOF mode 1 with a center over the Gulf Stream extension. Tide gauge and SST data are consistent in that both show a significant subdecadal periodicity exclusively in the subpolar gyre, but in subtropics the 12-14 year period is the prominent, but nonstationary, decadal signal. The main finding of this study is that this 12-14 year cycle can be constructed based on the leading mode of the surface heat flux. This connection to the surface heat flux implicates the participation of the thermohaline circulation in the decadal cycle. During the cycle starting from the positive index phase of NAO, SST and oceanic heat content anomalies are created in subtropics due to local heat flux and intensification of the thermohaline circulation. The anomalies advect to the subpolar gyre where they are amplified by local heat flux and are part of the negative feedback of thermohaline circulation on itself. Consequently the oceanic thermohaline circulation slows down and the opposite cycle starts. The oscillatory nature would not be possible without the active atmospheric participation in the cycle, because it provides the unstable interaction through heat flux, without it, the oceanic mode would be damped. This analysis suggests that the two principal modes of heat flux variability, corresponding to patterns similar to North Atlantic Oscillation (NAO) and Western Atlantic (WA), are part of the same decadal cycle and an indirect measure of the north-south movement of the storm tracks.

The Pelagics Habitat Analysis Module (PHAM): Decision Support Tools for Pelagic Fisheries

NASA Astrophysics Data System (ADS)

Armstrong, E. M.; Harrison, D. P.; Kiefer, D.; O'Brien, F.; Hinton, M.; Kohin, S.; Snyder, S.

2009-12-01

PHAM is a project funded by NASA to integrate satellite imagery and circulation models into the management of commercial and threatened pelagic species. Specifically, the project merges data from fishery surveys, and fisheries catch and effort data with satellite imagery and circulation models to define the habitat of each species. This new information on habitat will then be used to inform population distribution and models of population dynamics that are used for management. During the first year of the project, we created two prototype modules. One module, which was developed for the Inter-American Tropical Tuna Commission, is designed to help improve information available to manage the tuna fisheries of the eastern Pacific Ocean. The other module, which was developed for the Coastal Pelagics Division of the Southwest Fishery Science Center, assists management of by-catch of mako, blue, and thresher sharks along the Californian coast. Both modules were built with the EASy marine geographic information system, which provides a 4 dimensional (latitude, longitude, depth, and time) home for integration of the data. The projects currently provide tools for automated downloading and geo-referencing of satellite imagery of sea surface temperature, height, and chlorophyll concentrations; output from JPL’s ECCO2 global circulation model and its ROM California current model; and gridded data from fisheries and fishery surveys. It also provides statistical tools for defining species habitat from these and other types of environmental data. These tools include unbalanced ANOVA, EOF analysis of satellite imagery, and multivariate search routines for fitting fishery data to transforms of the environmental data. Output from the projects consists of dynamic maps of the distribution of the species that are driven by the time series of satellite imagery and output from the circulation models. It also includes relationships between environmental variables and recruitment. During the talk, we will briefly demonstrate features of the software and present the results of our analyses of habitats.

Tropical Cyclone Signatures in Atmospheric Convective Available Potential Energy

NASA Astrophysics Data System (ADS)

Studholme, Joshua; Gulev, Sergey

2016-04-01

Tropical cyclones play an important role in the climate system providing transports of energy and water vapor, forcing the ocean, and also affecting mid-latitude circulation phenomena. Tropical cyclone tracks experience strong interannual variability and in addition, longer term trend-like changes in all ocean basins. Analysis of recent historical data reveal a poleward shift in the locations of tropical cyclone tracks in both the Northern and Southern Hemispheres (Kossin et al. 2014, Nature, 509, 349-352). The physical consequences of these alterations are largely unconstrained. For example, the increasing encroachment of tropical cyclone activity into the extra-tropical environment presents a novel and still poorly understood paradigm for tropical-extratropical interactions. In this respect, the role that the atmospheric convective available potential energy (CAPE) plays in the dynamics of tropical cyclones is highly interesting. The two characteristic global-scale spatial patterns in CAPE are identified using EOF analysis. The first pattern shows an abundance of CAPE in the centre of the Pacific and corresponds to the El Nino Southern Oscillation. The second one is capturing positive CAPE anomalies in the oceanic tropics and negative anomalies over equatorial Africa. Associated with these buoyancy patterns, alterations in tropical cyclone activity occur in all basins forming both zonal and meridional patterns. Atmospheric buoyancy is the trigger for deep convection, and subsequently cyclone genesis. This is the mechanism of impact upon location at the start of cyclone tracks. It is found to have less impact upon where cyclones subsequently move, whether or not they undergo extratropical transition and when and where they experience lysis. It is shown that CAPE plays a critical role in the general circulation in the tropics which in turn is the larger steering context for embedded systems within the Walker and Hadley cells. So this lack of `latter life' impact posits an interesting start for further theoretical and physical consideration.

High time-resolved elemental components in fine and coarse particles in the Pearl River Delta region of Southern China: Dynamic variations and effects of meteorology.

PubMed

Zhou, Shengzhen; Davy, Perry K; Wang, Xuemei; Cohen, Jason Blake; Liang, Jiaquan; Huang, Minjuan; Fan, Qi; Chen, Weihua; Chang, Ming; Ancelet, Travis; Trompetter, William J

2016-12-01

Hourly-resolved PM 2.5 and PM 10-2.5 samples were collected in the industrial city Foshan in the Pearl River Delta region, China. The samples were subsequently analyzed for elemental components and black carbon (BC). A key purpose of the study was to understand the composition of particulate matter (PM) at high-time resolution in a polluted urban atmosphere to identify key components contributing to extreme PM concentration events and examine the diurnal chemical concentration patterns for air quality management purposes. It was found that BC and S concentrations dominated in the fine mode, while elements with mostly crustal and oceanic origins such as Si, Ca, Al and Cl were found in the coarse size fraction. Most of the elements showed strong diurnal variations. S did not show clear diurnal variations, suggesting regional rather than local origin. Based on empirical orthogonal functions (EOF) method, 3 forcing factors were identified contributing to the extreme events of PM 2.5 and selected elements, i.e., urban direct emissions, wet deposition and a combination of coarse mode sources. Conditional probability functions (CPF) were performed using wind profiles and elemental concentrations. The CPF results showed that BC and elemental Cl, K, Fe, Cu and Zn in the fine mode were mostly from the northwest, indicating that industrial emissions and combustion were the main sources. For elements in the coarse mode, Si, Al, K, Ca, Fe and Ti showed similar patterns, suggesting same sources such as local soil dust/construction activities. Coarse elemental Cl was mostly from the south and southeast, implying the influence of marine aerosol sources. For other trace elements, we found vanadium (V) in fine PM was mainly from the sources located to the southeast of the measuring site. Combined with CPF results of S and V in fine PM, we concluded shipping emissions were likely an important elemental emission source. Copyright © 2016. Published by Elsevier B.V.

Reanalysis Intercomparison on a Surface Wind Statistical Downscaling Exercise over Northeastern North America.

NASA Astrophysics Data System (ADS)

Lucio-Eceiza, Etor E.; Fidel González-Rouco, J.; Navarro, Jorge; García-Bustamante, Elena; Beltrami, Hugo; Rojas-Labanda, Cristina

2017-04-01

The area of North Eastern North America is located in a privileged position for the study of the wind behaviour as it lies within the track of many of the extratropical cyclones that travel that half of the continent. During the winter season the cyclonic activity and wind intensity are higher in the region, offering a great opportunity to analyse the relationships of the surface wind field with various large-scale configurations. The analysis of the wind behaviour is conducted via a statistical downscaling method based on Canonical Correlation Analysis (CCA). This methodology exploits the relationships among the main modes of circulation over the North Atlantic and Pacific Sectors and the behaviour of an observational surface wind database. For this exercise, various predictor variables have been selected (surface wind, SLP, geopotential height at 850 and 500 hPa, and thermal thickness between these two levels), obtained by all the global reanalysis products available to date. Our predictand field consists of an observational surface wind dataset with 525 sites distributed over North Eastern North America that span over a period of about 60 years (1953-2010). These data have been previously subjected to an exhaustive quality control process. A sensitivity analysis of the methodology to different parameter configurations has been carried out, such as reanalysis product, window size, predictor variables, number of retained EOF and CCA modes, and crossvalidation subset (to test the robustness of the method). An evaluation of the predictive skill of the wind estimations has also been conducted. Overall, the methodology offers a good representation of the wind variability, which is very consistent between all the reanalysis products. The wind directly obtained from the reanalyses offer a better temporal correlation but a larger range, and in many cases, worst representation of the local variability. The long observational period has also permitted the study of intra to multidecadal variability as the statistical relationship obtained by this method also allows for the reconstruction of the regional wind behaviour back to the mid 19th century. For this task we have used two 20th century reanalysis products as well as two additional instrumental sea level pressure datasets.

Retrieval with Infrared Atmospheric Sounding Interferometer and Validation during JAIVEx

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

2008-01-01

A state-of-the-art IR-only retrieval algorithm has been developed with an all-season-global EOF Physical Regression and followed by 1-D Var. Physical Iterative Retrieval for IASI, AIRS, and NAST-I. The benefits of this retrieval are to produce atmospheric structure with a single FOV horizontal resolution (approx. 15 km for IASI and AIRS), accurate profiles above the cloud (at least) or down to the surface, surface parameters, and/or cloud microphysical parameters. Initial case study and validation indicates that surface, cloud, and atmospheric structure (include TBL) are well captured by IASI and AIRS measurements. Coincident dropsondes during the IASI and AIRS overpasses are used to validate atmospheric conditions, and accurate retrievals are obtained with an expected vertical resolution. JAIVEx has provided the data needed to validate the retrieval algorithm and its products which allows us to assess the instrument ability and/or performance. Retrievals with global coverage are under investigation for detailed retrieval assessment. It is greatly desired that these products be used for testing the impact on Atmospheric Data Assimilation and/or Numerical Weather Prediction.

Seasonal and interannual variability of surface CDOM in the South China Sea associated with El Niño

NASA Astrophysics Data System (ADS)

Ma, Jinfeng; Zhan, Haigang; Du, Yan

2011-04-01

Satellite imagery of SeaWiFS from October 1997 to November 2007 is used to investigate the dominant seasonal and interannual variations of the surface light absorption due to Colored Dissolved Organic Materials (CDOM) in the South China Sea (SCS). Results show that the spatial distribution of CDOM mimics the major features of the SCS basin-scale circulation. High values of CDOM are found in upwelling regions like southeast of Vietnam in summer and northwest of Luzon in winter. At a basin scale, CDOM is high in winter when upwelling is strong, solar shortwave radiation and stratification weak, and vertical mixing intense. Opposite conditions exist in spring and summer. Interannual variability of the basin-wide CDOM is characterized by abnormal troughs during the El Niño events. A strong relationship exists between the time series of the first EOF mode (for both winter and summer) and Niño 3.4 Index. Associations of these events with climatic and hydrographic properties (i.e. wind forcing, solar shortwave radiation, Ekman pumping, vertical mixing, sea surface height and temperature) are discussed.

Polymerized phospholipid bilayers as permanent coatings for small amine separations using mixed aqueous/organic capillary zone electrophoresis.

PubMed

Pei, Lei; Lucy, Charles A

2012-12-07

Phospholipid bilayer (SPB) coatings have been used in capillary electrophoresis to reduce the nonspecific adsorption between the capillary wall and cationic analytes. This paper describes the use of the polymerizable lipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (Diyne PC) as a permanent capillary coating. A supported phospholipid bilayer was formed on the capillary walls and polymerization was performed in situ using ultraviolet irradiation. The polymerization reaction was monitored by UV-visible absorbance spectroscopy and atomic force microscopy. The EOF of the polymerized Diyne PC coating was moderately suppressed (2.0×10(-4)cm(2)/Vs) compared to a non-polymerized Diyne PC bilayer (0.3×10(-4)cm(2)/Vs), but the stability was improved significantly. Separations of benzylamine, veratrylamine, phenylethylamine and tolyethylamine using a poly Diyne PC coated capillary yielded efficiency of 220,000-370,000 plates/m and peak asymmetry factor 0.48-1.18. Specifically, the poly(Diyne PC) coating provided improved separation resolution in NACE due to the reduced surface adsorption. Copyright © 2012 Elsevier B.V. All rights reserved.

On two-liquid AC electroosmotic system for thin films.

PubMed

Navarkar, Abhishek; Amiroudine, Sakir; Demekhin, Evgeny A

2016-03-01

Lab-on-chip devices employ EOF for transportation and mixing of liquids. However, when a steady (DC) electric field is applied to the liquids, there are undesirable effects such as degradation of sample, electrolysis, bubble formation, etc. due to large magnitude of electric potential required to generate the flow. These effects can be averted by using a time-periodic or AC electric field. Transport and mixing of nonconductive liquids remain a problem even with this technique. In the present study, a two-liquid system bounded by two rigid plates, which act as substrates, is considered. The potential distribution is derived by assuming a Boltzmann charge distribution and using the Debye-Hückel linearization. Analytical solution of this time-periodic system shows some effects of viscosity ratio and permittivity ratio on the velocity profile. Interfacial electrostatics is also found to play a significant role in deciding velocity gradients at the interface. High frequency of the applied electric field is observed to generate an approximately static velocity profile away from the Electric Double Layer (EDL). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controls on coastal dune morphology, shoreline erosion and barrier island response to extreme storms

USGS Publications Warehouse

Houser, C.; Hapke, C.; Hamilton, S.

2008-01-01

The response of a barrier island to an extreme storm depends in part on the surge elevation relative to the height and extent of the foredunes which can exhibit considerable variability alongshore. While it is recognized that alongshore variations in dune height and width direct barrier island response to storm surge, the underlying causes of the alongshore variation remain poorly understood. This study examines the alongshore variation in dune morphology along a 11 km stretch of Santa Rosa Island in northwest Florida and relates the variation in morphology to the response of the island during Hurricane Ivan and historic and storm-related rates of shoreline erosion. The morphology of the foredune and backbarrier dunes was characterized before and after Hurricane Ivan using Empirical Orthogonal Function (EOF) analysis and related through Canonical Correlation Analysis (CCA). The height and extent of the foredune, and the presence and relative location of the backbarrier dunes, varied alongshore at discrete length scales (of ~ 750, 1450 and 4550 m) that are statistically significant at the 95% confidence level. Cospectral analysis suggests that the variation in dune morphology is correlated with transverse ridges on the inner-shelf, the backbarrier cuspate headlands, and the historical and storm-related trends in shoreline change. Sections of the coast with little to no dune development before Hurricane Ivan were observed in the narrowest portions of the island (between headlands), west of the transverse ridges. Overwash penetration tended to be larger in these areas and island breaching was common, leaving the surface close to the watertable and covered by a lag of shell and gravel. In contrast, large foredunes and the backbarrier dunes were observed at the widest sections of the island (the cuspate headlands) and at crest of the transverse ridges. Due to the large dunes and the presence of the backbarrier dunes, these areas experienced less overwash penetration and most of the sediment from the beachface and dunes was deposited within the upper-shoreface. It is argued that this sediment is returned to the beachface through nearshore bar migration following the storm and that the areas with larger foredunes and backbarrier dunes have smaller rates of historical shoreline erosion compared to areas with smaller dunes and greater transfer of sediment to the washover terrace. Since the recovery of the dunes will vary depending on the availability of sediment from the washover and beachface, it is further argued that the alongshore pattern of dune morphology and the response of the island to the next extreme storm is forced by the transverse ridges and island width through alongshore variations in storm surge and overwash gradients respectively. These findings may be particularly important for coastal managers involved in the repair and rebuilding of coastal infrastructure that was damaged or destroyed during Hurricane Ivan.

Spatial-temporal bio-optical classification of dynamic semi-estuarine waters in western North America

NASA Astrophysics Data System (ADS)

Phillips, Stephen Robert; Costa, Maycira

2017-12-01

The use of standard ocean colour reflectance based algorithms to derive surface chlorophyll may have limited applicability for optically dynamic coastal waters due to the pre-defined coefficients based on global datasets. Reflectance based algorithms adjusted to regional optical water characteristics are a promising alternative. A class-based definition of optically diverse coastal waters was investigated as a first step towards the development of temporal and spatial constrained reflectance based algorithms for optically variable coastal waters. A large set of bio-optical data were collected as part of five research cruises and bi-weekly trips aboard a ship of opportunity in the west coast of Canada, to assess the spatial and temporal variability of above-water reflectance in this contrasted coastal environment. To accomplish this, in situ biophysical and optical measurements were collected in conjunction with above-water hyperspectral remote sensing reflectance (Rrs) at 145 stations. The concentrations of measured biophysical data varied considerably; chlorophyll a (Chla) (mean = 1.64, range: 0.10-7.20 μg l-1), total suspended matter (TSM) (3.09, 0.82-20.69 mg l-1), and absorption by chromophoric dissolved organic matter (CDOM) (acdom(443 nm)) (0.525, 0.007-3.072 m-1), thus representing the spatio-temporal variability of the Salish Sea. Optically, a similar large range was also found; particulate scattering (bp(650 nm)) (1.316, 0.250-7.450 m-1), particulate backscattering (bbp(650 nm)) (0.022, 0.005-0.097 m-1), total beam attenuation coefficient (ct(650)) (1.675, 0.371-9.537 m-1) and particulate absorption coefficient (ap(650 nm)) (0.345, 0.048-2.020 m-1). An empirical orthogonal function (EOF) analysis revealed that Rrs variability was highly correlated to bp (r = 0.90), bbp (r = 0.82) and concentration of TSM (r = 0.80), which highlighted the dominant role of water turbidity in this region. Hierarchical clustering analysis was applied to the normalized Rrs spectra to define optical water classes. Class 1 was defined by the highest Rrs values, particularly above 570 nm, indicating more turbid waters; Class 2 was dominated by high Chla and TSM concentrations, which is shown by high Rrs at 570 nm as well as fluorescence and absorption peaks; Class 3 shows strong fluorescence signatures accompanied by low TSM influence; and Class 4 is most representative of clear waters with a less defined absorption peak around 440 nm. By understanding the bio-optical factors which control the variability of the Rrs spectra this study aims to develop a sub-regional characterization of this coastal region aiming to improve bio-optical algorithms in this complex coastal area.

Modes of Arctic Ocean Change from GRACE, ICESat and the PIOMAS and ECCO2 Models of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Peralta Ferriz, C.; Morison, J. H.; Bonin, J. A.; Chambers, D. P.; Kwok, R.; Zhang, J.

2012-12-01

EOF analysis of month-to-month variations in GRACE derived Arctic Ocean bottom pressure (OBP) with trend and seasonal variation removed yield three dominant modes. The first mode is a basin wide variation in mass associated with high atmospheric pressure (SLP) over Scandinavia mainly in winter. The second mode is a shift of mass from the central Arctic Ocean to the Siberian shelves due to low pressure over the basins, associated with the Arctic Oscillation. The third mode is a shift in mass between the Eastern and Western Siberian shelves, related to strength of the Beaufort High mainly in summer, and to eastward alongshore winds on the Barents Sea in winter. The PIOMAS and ECCO2 modeled OBP show fair agreement with the form of these modes and provide context in terms of variations in sea surface height SSH. Comparing GRACE OBP from 2007 to 2011 with GRACE OBP from 2002 to 2006 reveals a rising trend over most of the Arctic Ocean but declines in the Kara Sea region and summer East Siberian Sea. ECCO2 bears a faint resemblance to the observed OBP change but appears to be biased negatively. In contrast, PIOMAS SSH and ECCO2 especially, show changes between the two periods that are muted but similar to ICESat dynamic ocean topography and GRACE-ICESat freshwater trends from 2005 through 2008 [Morison et al., 2012] with a rising DOT and freshening in the Beaufort Sea and a trough with decreased freshwater on the Russian side of the Arctic Ocean. Morison, J., R. Kwok, C. Peralta-Ferriz, M. Alkire, I. Rigor, R. Andersen, and M. Steele (2012), Changing Arctic Ocean freshwater pathways, Nature, 481(7379), 66-70.

GRACE Solutions for the Gravity Field over Central Europe Compared to the Surface Field as Recorded by the GGP Network.

NASA Astrophysics Data System (ADS)

Crossley, D. J.; de Linage, C.; Hinderer, J.; Boy, J.

2007-12-01

As the number of different solutions from the GRACE satellite gravity project evolves, we can make more meaningful comparisons between the satellite-derived field and the surface field as recorded by superconducting gravimeters. On the GRACE side, we use CSR Level 2 products RL01 and the recent RL04 solutions, GFZ RL04 solutions, and the CNES/GRGS 10-day solutions, all for the time periods these are available. On the GGP side, we take advantage of the 10 years of SG data since July 1997 from 6-8 ground stations in Europe, allowing for the change in the network configuration as stations begin and end recording. Only data since 2002 can be compared directly to GRACE. Our primary measure of variability is the first principal component of the EOF analysis of all the fields. Unsurprisingly, the seasonal components for all the comparisons are similar in phase, but different in amplitude, to the predictions from a global hydrology model (GLDAS), provided allowance is made for the location of the SG stations above or below the soil moisture horizon that controls the gravity signature. We use detailed modeling at the Strasbourg station, as well as published results for Moxa and Membach, to confirm the gravity effect of hydrology. Good agreement is found between the GGP and the CNES/GRGS 10-day solutions, indicating the higher temporal resolution of this satellite solution is valid for our limited geographical area. We also synthesize the gravity field over the sub-group of GGP stations in N.E. Asia to see how the GRACE variability compares to that for the European array and to assess future ground validation using new GGP stations in that part of the world.

Predictability and prediction of the total number of winter extremely cold days over China

NASA Astrophysics Data System (ADS)

Luo, Xiao; Wang, Bin

2018-03-01

The current dynamical climate models have limited skills in predicting winter temperature in China. The present study uses physics-based empirical models (PEMs) to explore the sources and limits of the seasonal predictability in the total number of extremely cold days (NECD) over China. A combined cluster-rotated EOF analysis reveals two sub-regions of homogeneous variability among hundreds of stations, namely the Northeast China (NE) and Main China (MC). This reduces the large-number of predictands to only two indices, the NCED-NE and NCED-MC, which facilitates detection of the common sources of predictability for all stations. The circulation anomalies associated with the NECD-NE exhibit a zonally symmetric Arctic Oscillation-like pattern, whereas those associated with the NECD-MC feature a North-South dipolar pattern over Asia. The predictability of the NECD originates from SST and snow cover anomalies in the preceding September and October. However, the two regions have different SST predictors: The NE predictor is in the western Eurasian Arctic while the MC predictor is over the tropical-North Pacific. The October snow cover predictors also differ: The NE predictor primarily resides in the central Eurasia while the MC predictor is over the western and eastern Eurasia. The PEM prediction results suggest that about 60% (55%) of the total variance of winter NECD over the NE (Main) China are likely predictable 1 month in advance. The NECD at each station can also be predicted by using the four predictors that were detected for the two indices. The cross-validated temporal correlation skills exceed 0.70 at most stations. The physical mechanisms by which the autumn Arctic sea ice, snow cover, and tropical-North Pacific SST anomalies affect winter NECD over the NE and Main China are discussed.

Identification of inorganic ions in post-blast explosive residues using portable CE instrumentation and capacitively coupled contactless conductivity detection.

PubMed

Hutchinson, Joseph P; Johns, Cameron; Breadmore, Michael C; Hilder, Emily F; Guijt, Rosanne M; Lennard, Chris; Dicinoski, Greg; Haddad, Paul R

2008-11-01

Novel CE methods have been developed on portable instrumentation adapted to accommodate a capacitively coupled contactless conductivity detector for the separation and sensitive detection of inorganic anions and cations in post-blast explosive residues from homemade inorganic explosive devices. The methods presented combine sensitivity and speed of analysis for the wide range of inorganic ions used in this study. Separate methods were employed for the separation of anions and cations. The anion separation method utilised a low conductivity 70 mM Tris/70 mM CHES aqueous electrolyte (pH 8.6) with a 90 cm capillary coated with hexadimethrine bromide to reverse the EOF. Fifteen anions could be baseline separated in 7 min with detection limits in the range 27-240 microg/L. A selection of ten anions deemed most important in this application could be separated in 45 s on a shorter capillary (30.6 cm) using the same electrolyte. The cation separation method was performed on a 73 cm length of fused-silica capillary using an electrolyte system composed of 10 mM histidine and 50 mM acetic acid, at pH 4.2. The addition of the complexants, 1 mM hydroxyisobutyric acid and 0.7 mM 18-crown-6 ether, enhanced selectivity and allowed the separation of eleven inorganic cations in under 7 min with detection limits in the range 31-240 microg/L. The developed methods were successfully field tested on post-blast residues obtained from the controlled detonation of homemade explosive devices. Results were verified using ion chromatographic analyses of the same samples.

Seasonal Predictability in a Model Atmosphere.

NASA Astrophysics Data System (ADS)

Lin, Hai

2001-07-01

The predictability of atmospheric mean-seasonal conditions in the absence of externally varying forcing is examined. A perfect-model approach is adopted, in which a global T21 three-level quasigeostrophic atmospheric model is integrated over 21 000 days to obtain a reference atmospheric orbit. The model is driven by a time-independent forcing, so that the only source of time variability is the internal dynamics. The forcing is set to perpetual winter conditions in the Northern Hemisphere (NH) and perpetual summer in the Southern Hemisphere.A significant temporal variability in the NH 90-day mean states is observed. The component of that variability associated with the higher-frequency motions, or climate noise, is estimated using a method developed by Madden. In the polar region, and to a lesser extent in the midlatitudes, the temporal variance of the winter means is significantly greater than the climate noise, suggesting some potential predictability in those regions.Forecast experiments are performed to see whether the presence of variance in the 90-day mean states that is in excess of the climate noise leads to some skill in the prediction of these states. Ensemble forecast experiments with nine members starting from slightly different initial conditions are performed for 200 different 90-day means along the reference atmospheric orbit. The serial correlation between the ensemble means and the reference orbit shows that there is skill in the 90-day mean predictions. The skill is concentrated in those regions of the NH that have the largest variance in excess of the climate noise. An EOF analysis shows that nearly all the predictive skill in the seasonal means is associated with one mode of variability with a strong axisymmetric component.

Multi-platform validation of a high-resolution model in the Western Mediterranean Sea: insight into spatial-temporal variability

NASA Astrophysics Data System (ADS)

Aguiar, Eva; Mourre, Baptiste; Heslop, Emma; Juza, Mélanie; Escudier, Romain; Tintoré, Joaquín

2017-04-01

This study focuses on the validation of the high resolution Western Mediterranean Operational model (WMOP) developed at SOCIB, the Balearic Islands Coastal Observing and Forecasting System. The Mediterranean Sea is often seen as a small scale ocean laboratory where energetic eddies, fronts and circulation features have important ecological consequences. The Medclic project is a program between "La Caixa" Foundation and SOCIB which aims at characterizing and forecasting the "oceanic weather" in the Western Mediterranean Sea, specifically investigating the interactions between the general circulation and mesoscale processes. We use a WMOP 2009-2015 free run hindcast simulation and available observational datasets (altimetry, moorings and gliders) to both assess the numerical simulation and investigate the ocean variability. WMOP has a 2-km spatial resolution and uses CMEMS Mediterranean products as initial and boundary conditions, with surface forcing from the high-resolution Spanish Meteorological Agency model HIRLAM. Different aspects of the spatial and temporal variability in the model are validated from local to regional and basin scales: (1) the principal axis of variability of the surface circulation using altimetry and moorings along the Iberian coast, (2) the inter-annual changes of the surface flows incorporating also glider data, (3) the propagation of mesoscale eddies formed in the Algerian sub-basin using altimetry, and (4) the statistical properties of eddies (number, rotation, size) applying an eddy tracker detection method in the Western Mediterranean Sea. With these key points evaluated in the model, EOF analysis of sea surface height maps are used to investigate spatial patterns of variability associated with eddies, gyres and the basis-scale circulation and so gain insight into the interconnections between sub-basins, as well as the interactions between physical processes at different scales.

On the fog variability over south Asia

NASA Astrophysics Data System (ADS)

Syed, F. S.; Körnich, H.; Tjernström, M.

2012-12-01

An increasing trend in fog frequencies over south Asia during winter in the last few decades has resulted in large economical losses and has caused substantial difficulties in the daily lives of people. In order to better understand the fog phenomenon, we investigated the climatology, inter-annual variability and trends in the fog occurrence from 1976 to 2010 using observational data from 82 stations, well distributed over India and Pakistan. Fog blankets large area from Pakistan to Bangladesh across north India from west to east running almost parallel to south of the Himalayas. An EOF analysis revealed that the fog variability over the whole region is coupled and therefore must be governed by some large scale phenomenon on the inter-annual time scale. Significant positive trends were found in the fog frequency but this increase is not gradual, as with the humidity, but comprises of two distinct regimes shifts, in 1990 and 1998, with respect to both mean and variance. The fog is also detected in ERA-Interim 3 hourly, surface and model level forecast data when using the concept of "cross-over temperature" combined with boundary layer stability. This fog index is able to reproduce the regime shift around 1998 and shows that the method can be applied to analyze fog over south Asia. The inter-annual variability seems to be associated with the wave train originating from the North Atlantic in the upper troposphere that when causing higher pressure over the region results in an increased boundary layer stability and surface-near relative humidity. The trend and shifts in the fog occurrence seems to be associated with the gradual increasing trend in relative humidity from 1990 onwards.

Interannual lake level fluctuations (1993 1999) in Africa from Topex/Poseidon: connections with ocean atmosphere interactions over the Indian Ocean

NASA Astrophysics Data System (ADS)

Mercier, Franck; Cazenave, Anny; Maheu, Caroline

2002-04-01

Water level fluctuations of continental lakes are related to regional to global scale climate changes. Water level fluctuations reflect variations in evaporation and precipitation over the lake area and its catchment area. Over such inland water bodies, the satellite altimetry technique offers both a world-wide coverage and a satisfying accuracy. We present here results of lake level variations of 12 African lakes based on 7 years of Topex/Poseidon (T/P) altimetry data acquired between 1993 and 1999. Among the 12 African lakes presented in this study, three are reservoirs whose level fluctuations are mainly driven by anthropogenic usage of the water. Either closed or open, the nine remaining lakes are sensitive indicators of the climate evolution over Africa during the 1990s. Seasonal signals of each lake are clearly identified and filtered out to focus on the interannual fluctuations. Clear correlated regional variations are reported among the east African lakes: several lakes exhibit a regular level decrease between 1993 and 1997, probably due to intense droughts. However, the most spectacular feature is an abrupt water level rise occurring in late 1997-early 1998 and affecting most of the lakes located within the Rift Valley. This major anomalous pattern, explained by a large excess rainfall anomaly occurring in late 1997, is quantified in both space and time domains through an EOF analysis of the lake level height time series. The spatial distribution of the leading mode of lake level height correlates with the dominant mode of precipitation computed over the same time span. Nevertheless, similar rainfall anomaly, but with lesser intensity, occurred in late 1994 without any noticeable consequence on lake level. The precipitation anomaly appears related to the equatorial Indian Ocean warming reported during the 1997-1998 ENSO event.

Analyses of gibberellins in coconut (Cocos nucifera L.) water by partial filling-micellar electrokinetic chromatography-mass spectrometry with reversal of electroosmotic flow.

PubMed

Ge, Liya; Yong, Jean Wan Hong; Tan, Swee Ngin; Hua, Lin; Ong, Eng Shi

2008-05-01

In this paper, we present the results of simultaneous screening of eight gibberellins (GAs) in coconut (Cocos nucifera L.) water by MEKC directly coupled to ESI-MS detection. During the development of MEKC-MS, partial filling (PF) was used to prevent the micelles from reaching the mass spectrometer as this is detrimental to the MS signal, and a cationic surfactant, cetyltrimethylammonium hydroxide, was added to the electrolyte to reverse the EOF. On the basis of the resolution of the neighboring peaks, different parameters (i.e., the pH and concentration of buffer, surfactant concentrations, length of the injected micellar plug, organic modifier, and applied separation voltage) were optimized to achieve a satisfactory PF-MEKC separation of eight GA standards. Under optimum conditions, a baseline separation of GA standards, including GA1, GA3, GA5, GA6, GA7, GA9, GA12, and GA13, was accomplished within 25 min. Satisfactory results were obtained in terms of precision (RSD of migration time below 0.9%), sensitivity (LODs in the range of 0.8-1.9 microM) and linearity (R2 between 0.981 and 0.997). MS/MS with multiple reaction monitoring (MRM) detection was carried out to obtain sufficient selectivity. PF-MEKC-MS/MS allowed the direct identification and confirmation of the GAs presented in coconut water (CW) sample after SPE, while, the quantitative analysis of GAs was performed by PF-MEKC-MS approach. GA1 and GA3 were successfully detected and quantified in CW. It is anticipated that the current PF-MEKC-MS method can be applicable to analyze GAs in a wide range of biological samples.

Large-Scale Atmospheric Teleconnection Patterns Associated with the Interannual Variability of Heatwaves in East Asia and Its Decadal Changes

NASA Astrophysics Data System (ADS)

Choi, N.; Lee, M. I.; Lim, Y. K.; Kim, K. M.

2017-12-01

Heatwave is an extreme hot weather event which accompanies fatal damage to human health. The heatwave has a strong relationship with the large-scale atmospheric teleconnection patterns. In this study, we examine the spatial pattern of heatwave in East Asia by using the EOF analysis and the relationship between heatwave frequency and large-scale atmospheric teleconnection patterns. We also separate the time scale of heatwave frequency as the time scale longer than a decade and the interannual time scale. The long-term variation of heatwave frequency in East Asia shows a linkage with the sea surface temperature (SST) variability over the North Atlantic with a decadal time scale (a.k.a. the Atlantic Multidecadal Oscillation; AMO). On the other hands, the interannual variation of heatwave frequency is linked with the two dominant spatial patterns associated with the large-scale teleconnection patterns mimicking the Scandinavian teleconnection (SCAND-like) pattern and the circumglobal teleconnection (CGT-like) pattern, respectively. It is highlighted that the interannual variation of heatwave frequency in East Asia shows a remarkable change after mid-1990s. While the heatwave frequency was mainly associated with the CGT-like pattern before mid-1990s, the SCAND-like pattern becomes the most dominant one after mid-1990s, making the CGT-like pattern as the second. This study implies that the large-scale atmospheric teleconnection patterns play a key role in developing heatwave events in East Asia. This study further discusses possible mechanisms for the decadal change in the linkage between heatwave frequency and the large-scale teleconnection patterns in East Asia such as early melting of snow cover and/or weakening of East Asian jet stream due to global warming.

Assimilation of satellite altimeter data in a primitive-equation model of the Azores Madeira region

NASA Astrophysics Data System (ADS)

Gavart, Michel; De Mey, Pierre; Caniaux, Guy

1999-07-01

The aim of this study is to implement satellite altimetric assimilation into a high-resolution primitive-equation ocean model and check the validity and sensitivity of the results. Beyond this paper, the remote objective is to get a dynamical tool capable of simulating the surface ocean processes linked to the air-sea interactions as well as to perform mesoscale ocean forecasting. For computational cost and practical reasons, this study takes place in a 1000 by 1000 sq km open domain of the Canary basin. The assimilation experiments are carried out with the combined TOPEX/POSEIDON and ERS-1 data sets between June 1993 and December 1993. The space-time domain overlaps with in situ data collected during the SEMAPHORE experiment and thus enables an objective validation of the results. A special boundary treatment is applied to the model by creating a surrounding recirculating area separated from the interior by a buffer zone. The altimetric assimilation is done by implementing a reduced-order optimal interpolation algorithm with a special vertical projection of the surface model/data misfits. We perform a first experiment with a vertical projection onto an isopycnal EOF representing the Azores Current vertical variability. An objective validation of the model's velocities with Lagrangian float data shows good results (the correlation is 0.715 at 150 dbar). The question of the sensitivity to the vertical projection is addressed by performing similar experiments using a method for lifting/lowering of the water column, and using an EOF in Z-coordinates. Some comparisons with in situ temperature data do not show any significant difference between the three projections, after five months of assimilation. However, in order to preserve the large-scale water characteristics, we felt that the isopycnal projection was a more physically consistent choice. Then, the complementary character of the two satellites is assessed with two additional experiments which use each altimeter data sets separately. There is an evidence of the benefit of combining the two data sets. Otherwise, an experiment assimilating long-wavelength bias-corrected CLS altimetric maps every 10 days exhibits the best correlation scores and emphasizes the importance of reducing the orbit error and biases in the altimetric data sets. The surface layers of the model are forced using realistic daily wind stress values computed from ECMWF analyses. Although we resolve small space and time scales, in our limited domain the wind stress does not significantly influence the quality of the results obtained with the altimetric assimilation. Finally, the relative effects of the data selection procedure and of the integration times (cycle lengths) is explored by performing data window experiments. A value of 10 days seems to be the most satisfactory cycle length.

Variations of Sea Surface Temperature, Wind Stress, and Rainfall over the Tropical Atlantic and South America.

NASA Astrophysics Data System (ADS)

Nobre, Paulo; Srukla, J.

1996-10-01

Empirical orthogonal functions (E0Fs) and composite analyses are used to investigate the development of sea surface temperature (SST) anomaly patterns over the tropical Atlantic. The evolution of large-scale rainfall anomaly patterns over the equatorial Atlantic and South America are also investigated. 71e EOF analyses revealed that a pattern of anomalous SST and wind stress asymmetric relative to the equator is the dominant mode of interannual and longer variability over the tropical Atlantic. The most important findings of this study are as follows.Atmospheric circulation anomalies precede the development of basinwide anomalous SST patterns over the tropical Atlantic. Anomalous SST originate off the African coast simultaneously with atmospheric circulation anomalies and expand westward afterward. The time lag between wind stress relaxation (strengthening) and maximum SST warming (cooling) is about two months.Anomalous atmospheric circulation patterns over northern tropical Atlantic are phase locked to the seasonal cycle. Composite fields of SLP and wind stress over northern tropical Atlantic can be distinguished from random only within a few months preceding the March-May (MAM) season. Observational evidence is presented to show that the El Niño-Southern Oscillation phenomenon in the Pacific influences atmospheric circulation and SST anomalies over northern tropical Atlantic through atmospheric teleconnection patterns into higher latitudes of the Northern Hemisphere.The well-known droughts over northeastern Brazil (Nordeste) are a local manifestation of a much larger-scale rainfall anomaly pattern encompassing the whole equatorial Atlantic and Amazon region. Negative rainfall anomalies to the south of the equator during MAM, which is the rainy season for the Nordeste region, are related to an early withdrawal of the intertropical convergence zone toward the warm SST anomalies over the northern tropical Atlantic. Also, it is shown that precipitation anomalies over southern and northern parts of the Nordeste are out of phase: drought years over the northern Nordeste are commonly preceded by wetter years over the southern Nordeste, and vice versa.

Reconstruction and downscaling of Eastern Mediterranean OSCAR satellite surface current data using DINEOF

NASA Astrophysics Data System (ADS)

Nikolaidis, Andreas; Stylianou, Stavros; Georgiou, Georgios; Hajimitsis, Diofantos; Gravanis, Elias; Akylas, Evangelos

2015-04-01

During the last decade, Rixen (2005) and Alvera-Azkarate (2010) presented the DINEOF (Data Interpolating Empirical Orthogonal Functions) method, a EOF-based technique to reconstruct missing data in satellite images. The application of DINEOF method, proved to provide relative success in various experimental trials (Wang and Liu, 2013; Nikolaidis et al., 2013;2014), and tends to be an effective and computationally affordable solution, on the problem of data reconstruction, for missing data from geophysical fields, such as chlorophyll-a, sea surface temperatures or salinity and geophysical fields derived from satellite data. Implementation of this method in a GIS system will provide with a more complete, integrated approach, permitting the expansion of the applicability over various aspects. This may be especially useful in studies where various data of different kind, have to be examined. For this purpose, in this study we have implemented and present a GIS toolbox that aims to automate the usage of the algorithm, incorporating the DINEOF codes provided by GHER (GeoHydrodynamics and Environment Research Group of University of Liege) into the ArcGIS®. ArcGIS® is a well known standard on Geographical Information Systems, used over the years for various remote sensing procedures, in sea and land environment alike. A case-study of filling the missing satellite derived current data in the Eastern Mediterranean Sea area, for a monthly period is analyzed, as an example for the effectiveness and simplicity of the usage of this toolbox. The specific study focuses to OSCAR satellite data (http://www.oscar.noaa.gov/) collected by NOAA/NESDIS Operational Surface Current Processing and Data Center, from the respective products of OSCAR Project Office Earth and Space Research organization, that provides free online access to unfiltered (1/3 degree) resolution. All the 5-day mean products data coverage were successfully reconstructed. KEY WORDS: Remote Sensing, Cyprus, Mediterranean, DINEOF, ArcGIS, data reconstruction.

Postural stability and history of falls in cognitively able older adults: the Canton Ticino study.

PubMed

Merlo, Andrea; Zemp, Damiano; Zanda, Enrica; Rocchi, Sabrina; Meroni, Fabiano; Tettamanti, Mauro; Recchia, Angela; Lucca, Ugo; Quadri, Pierluigi

2012-09-01

Falls are common events in the elderly and represent the main risk factor for fractures and other injuries. Strategies for fall prevention rely on the multifactorial assessment of the risk of falling. The contribution of instrumented balance assessment to the prediction of falls remains unclear in the literature. In this study, we analyzed the association between the fall-history of a wide sample of older people without dementia and the values of a set of posturographic parameters acquired in different visual, proprioceptive and mental conditions. A consecutive sample of 130 cognitively able elderly subjects, age≥70 years, was analyzed. Based on their fall-history in the last year, subjects were categorized into non-fallers (NF), fallers (F) and recurrent fallers (RF>2 falls). Each subject was assessed by measurements of cognition and functional ability. Static posturography tests were performed in five conditions: with eyes open/close (EO/EC) on a firm/compliant (FS/CS) surface and while performing a cognitive task. The center of pressure (COP) mean position referred to the mid-point of the heels, area of the 95% confidence ellipse, sway mean velocities and RMS displacements in the antero-posterior (AP) and medio-lateral (ML) directions were computed and their association with the fall-history was assessed. The mean position of the COP in the AP direction and the confidence ellipse area were associated with the fall-history in the EOFS, ECFS and EOCS conditions (P<0.05). RMS displacements were also associated with the fall-history in the EOCS condition (P<0.05). Significant group differences (P<0.05) were found in the EOCS conditions, which greatly enhanced the differences among NF, F and RF. The ability to control balance while standing with eyes open on a compliant surface showed a high degree of association with the fall-history of older people with no or mild cognitive impairment. Copyright © 2012 Elsevier B.V. All rights reserved.

Numerical simulation and prediction of coastal ocean circulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, P.

1992-01-01

Numerical simulation and prediction of coastal ocean circulation have been conducted in three cases. 1. A process-oriented modeling study is conducted to study the interaction of a western boundary current (WBC) with coastal water, and its responses to upstream topographic irregularities. It is hypothesized that the interaction of propagating WBC frontal waves and topographic Rossby waves are responsible for upstream variability. 2. A simulation of meanders and eddies in the Norwegian Coastal Current (NCC) for February and March of 1988 is conducted with a newly developed nested dynamic interactive model. The model employs a coarse-grid, large domain to account formore » non-local forcing and a fine-grid nested domain to resolve meanders and eddies. The model is forced by wind stresses, heat fluxes and atmospheric pressure corresponding Feb/March of 1988, and accounts for river/fjord discharges, open ocean inflow and outflow, and M[sub 2] tides. The simulation reproduced fairly well the observed circulation, tides, and salinity features in the North Sea, Norwegian Trench and NCC region in the large domain and fairly realistic meanders and eddies in the NCC in the nested region. 3. A methodology for practical coastal ocean hindcast/forecast is developed, taking advantage of the disparate time scales of various forcing and considering wind to be the dominant factor in affecting density fluctuation in the time scale of 1 to 10 days. The density field obtained from a prognostic simulation is analyzed by the empirical orthogonal function method (EOF), and correlated with the wind; these information are then used to drive a circulation model which excludes the density calculation. The method is applied to hindcast the circulation in the New York Bight for spring and summer season of 1988. The hindcast fields compare favorably with the results obtained from the prognostic circulation model.« less

Past and future impact of North Atlantic teleconnection patterns on the hydroclimate of the Caspian catchment area in CESM1.2.2 and observations

NASA Astrophysics Data System (ADS)

Nandini, Sri

2017-04-01

The Caspian Sea level has undergone dramatic variations of more than 3 m during the past century with important implications for the life of coastal people, economy and the ecosystem. The origin of these variations as well as future changes in the Caspian water budget are still a matter of debate. In this study, we examine the influence of the major seasonal North Atlantic teleconnection patterns, the North Atlantic Oscillation (NAO), the East Atlantic pattern (EA), the Scandinavian pattern (SCA), and the North Sea Caspian Pattern (NCP), on Caspian hydroclimate variability from 1850-2000 CE. Numerical experiments at different atmospheric grid resolutions (2° and 1°) are carried out with the coupled Community Earth System Model (CESM1.2.2). We test model skills under different resolutions through validation against observational data by various statistical methods (Empirical Orthogonal Functions, Taylor diagrams, linear regressions and Spearman rank correlation). Results reveal the strongest simulated signal in winter (DJF) with high explained variances for 1° CESM1.2.2 NAO (39%) and EA (15.7%), similar to observational data. The model is unable to reproduce the SCA pattern in the third EOF, which is found in the observations. The modelled NAO has a strong influence on winter temperature and rainfall over the Caspian catchment area. A strong winter NCP induces above-average 2-meter temperatures over north Caspian region and lower-than-normal precipitation over the eastern Caspian sea. Our study suggests that the 1° version of CESM1.2.2 (with CAM5 atmosphere physics) shows adequate performance with respect to teleconnection maps during the historical period. Lastly, 1° model climate projections (2005-2100 CE) are performed with different Representative Concentration Pathways (RCP 4.5 and RCP 8.5) to examine potential changes in the teleconnection patterns and their influence on the Caspian region.

Interdecadal changes in the Asian winter monsoon variability and its relationship with ENSO and AO

NASA Astrophysics Data System (ADS)

Yun, Kyung-Sook; Seo, Ye-Won; Ha, Kyung-Ja; Lee, June-Yi; Kajikawa, Yoshiyuki

2014-08-01

Interdecadal changes in the Asian winter monsoon (AWM) variability are investigated using three surface air temperature datasets for the 55-year period of 1958-2012 from (1) the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis 1 (NCEP), (2) combined datasets from the European Centre for Medium-range Weather Forecasts (ECMWF) 40-yr reanalysis and interim data (ERA), and (3) Japanese 55-year reanalysis (JRA). Particular attention has been paid to the first four empirical orthogonal function (EOF) modes of the AWM temperature variability that together account for 64% of the total variance and have been previously identified as predictable modes. The four modes are characterized as follows: the first mode by a southern warming over the Indo-western Pacific Ocean associated with a gradually increasing basin-wide warming trend; the second mode by northern warming with the interdecadal change after the late 1980s; the third and fourth modes by north-south triple pattern, which reveal a phase shift after the late 1970s. The three reanalyses agree well with each other when producing the first three modes, but show large discrepancy in capturing both spatial and temporal characteristics of the fourth mode. It is therefore considered that the first three leading modes are more reliable than the rest higher modes. Considerable interdecadal changes are found mainly in the first two modes. While the first mode shows gradually decreasing variance, the second mode exhibits larger interannual variance during the recent decade. In addition, after the late 1970s, the first mode has a weakening relationship with the El Niño-Southern Oscillation (ENSO) whereas the second mode has strengthening association with the Artic Oscillation (AO). This indicates an increasing role of AO but decreasing role of ENSO on the AWM variability. A better understanding of the interdecadal change in the dominant modes would contribute toward advancing in seasonal prediction and the predictability of the AWM variability.

Ozone and stratospheric height waves for opposite phases of the QBO

NASA Technical Reports Server (NTRS)

Mo, Kingtse C.; Nogues-Paegle, Julia

1994-01-01

The stratospheric quasi-biennial oscillation (QBO) provides an important source of interannual variations in the Northern Hemisphere. O'sullivan and Salby (1990) related extra-tropical eddy transport with the phase of the tropical QBO. When the tropical wind is easterly, the zero wind line is shifted into the winter hemisphere. Enhanced wave activity in middle latitudes acts to weaken the polar vortex. When the tropical wind is in the westerly phase the situation reverses. Heights at 30 mb and ozone configurations are contrasted in this paper for these two QBO phases. When the winter vortex deforms due to the amplification of planetary waves 1 and 2, extends westward and equatorward, the complementary band of low vorticity air spirals in toward the pole from lower latitudes. Sometimes, these planetary waves break (Juckes and McIntyre, 1987) and an irreversible mixing of air takes place between high and mid-latitudes. Global ozone patterns, as obtained form satellite observations, appear to be affected by planetary wave breaking (Leovy et al. 1985). This mixing results on regions with uniform ozone and potential vorticity. In the Southern Hemisphere (SH), Newman and Randel (1988) using Total Ozone Mapping Spectrometer (TOMS) data and the NMC analyses have found strong spatial correlation between the October mean temperature in the lower stratosphere and total ozone for the 1979 through 1986 years. Recently Nogues-Paegle et al.(1992) analyzed SH ozone and height data from 1986 to 1989. They found that leading empirical orthogonal functions (EOFs) for both ozone and 50 mb heights exhibit zonal wave 1 and 2 and that the correlations between ozone and 50 mb principal components (PCs) are high. The results were found to be consistent with a linear planetary wave advecting a passive tracer. In this paper, the dominant patterns of variability for 30 mb NMC heights and TOMS total ozone are obtained for the winter to summer transition (January to May) in the Northern Hemisphere (NH) for the years 1987-1990.

Triadic Non-Gaussian teleconnections in the Sea Surface Temperature Field: a source of interannual predictability coming from triadic wave resonances

NASA Astrophysics Data System (ADS)

Pires, Carlos; Trigo, Ricardo; Perdigão, Rui

2015-04-01

Analysis of centennial (1910-2012) time-series of the monthly Sea Surface Temperature anomalies (SSTAs) around the global ocean (extracted from the NOAA ERSST v3b dataset) shows clear evidence of non-Gaussian multivariate PDFs on certain projections, as an indication of both nonlinear correlations and nonlinear teleconnections. Beyond that, we still get statistical non-Gaussian relationships involving sets of three pair-wise uncorrelated variables through the occurrence of statistically significant and cross-validated triadic correlations (TCs),reaching ~30% in certain cases, i.e. non-null third-order cross cumulants between three standardized principal components (PCs) of the SSTA field, which would vanish under multivariate Gaussianity. Further enhanced TCs are obtained in the space of orthogonally rotated standardized PCs by expressing them as a function of the generalized Euler rotation angles and then maximized by gradient-descent methods. There are multiple triads depending of the embedding space of PCs where triads are sought. Furthermore they have no preferred order due to non-unique solutions of the non-linear matricial equations to be solved in the optimization. Triadic correlation is a particular form of the triadic interaction information, defined as the parcel of the mutual information (an Information-Theoretic measure of statistical dependency) which is atributed to triadic statistical synergies, not explained by pair-wise relationships. Spatial patterns of the triad's components generally exhibit wave-like structures in spatial quadrature and satisfying the triadic wave resonance condition. Examples of triads are given in spaces spanned by the leading EOFs of the SSTA field and projecting mostly in the Pacific Ocean (e.g. El Niño, Pacific Decadal Oscillation, North-Pacific Gyre Oscillation and pattrens of waves crossing the Pacific basin). A triadic correlation means a non-null Pearson correlation between the product of any two variables and the remaining third one. This nonlinear correlation may exhibit memory extending to months or years and may even be responsible for some skill recovery at the decadal scale. The triadic cumulant may de decomposed into Fourier cross bi-spectrum terms relying on components satisfying the triadic wave resonance. This holds when the frequency (in cycles per century) of a Fourier component is the sum of frequencies of the other two Fourier components. Therefore, dominant resonances between components interacting constructively, i.e. satisfying the appropriate phase relationship, can be considered as nonlinear sources of predictability on scales ranging from months to decades. The triads and indices derived from them can be used in schemes of long-range forecasting and downscaling.

What controls the variability of oxygen in the subpolar North Pacific?

NASA Astrophysics Data System (ADS)

Takano, Yohei

Dissolved oxygen is a widely observed chemical quantity in the oceans along with temperature and salinity. Changes in the dissolved oxygen have been observed over the world oceans. Observed oxygen in the Ocean Station Papa (OSP, 50°N, 145°W) in the Gulf of Alaska exhibits strong variability over interannual and decadal timescales, however, the mechanisms driving the observed variability are not yet fully understood. Furthermore, irregular sampling frequency and relatively short record length make it difficult to detect a low-frequency variability. Motivated by these observations, we investigate the mechanisms driving the low-frequency variability of oxygen in the subpolar North Pacific. The specific purposes of this study are (1) to evaluate the robustness of the observed low-frequency variability of dissolved oxygen and (2) to determine the mechanisms driving the observed variability using statistical data analysis and numerical simulations. To evaluate the robustness of the low-frequency variability, we conducted spectral analyses on the observed oxygen at OSP. To address the irregular sampling frequency we randomly sub-sampled the raw data to form 500 ensemble members with a regular time interval, and then performed spectral analyses. The resulting power spectrum of oxygen exhibits a robust low-frequency variability and a statistically significant spectral peak is identified at a timescale of 15--20 years. The wintertime oceanic barotropic streamfunction is significantly correlated with the observed oxygen anomaly at OSP with a north-south dipole structure over the North Pacific. We hypothesize that the observed low-frequency variability is primarily driven by the variability of large-scale ocean circulation in the North Pacific. To test this hypothesis, we simulate the three-dimensional distribution of oxygen anomaly between 1952 to 2001 using data-constrained circulation fields. The simulated oxygen anomaly shows an outstanding variability in the Gulf of Alaska, showing that this region is a hotspot of oxygen fluctuation. Anomalous advection acting on the climatological mean oxygen gradient is the source of oxygen variability in this simulation. Empirical Orthogonal Function (EOF) analyses of the simulated oxygen show that the two dominant modes of the oxygen anomaly explains more than 50% of oxygen variance over the North Pacific, that are closely related to the dominant modes of climate variability in the North Pacific (Pacific Decadal Oscillation and North Pacific Oscillation). Our results imply the important link between large-scale climate fluctuations, ocean circulation and biogeochemical tracers in the North Pacific.