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1

Asian Dust Weather Categorization with Satellite and Surface Observations  

NASA Technical Reports Server (NTRS)

This study categorizes various dust weather types by means of satellite remote sensing over central Asia. Airborne dust particles can be identified by satellite remote sensing because of the different optical properties exhibited by coarse and fine particles (i.e. varying particle sizes). If a correlation can be established between the retrieved aerosol optical properties and surface visibility, the intensity of dust weather can be more effectively and consistently discerned using satellite rather than surface observations. In this article, datasets consisting of collocated products from Moderate Resolution Imaging Spectroradiometer Aqua and surface measurements are analysed. The results indicate an exponential relationship between the surface visibility and the satellite-retrieved aerosol optical depth, which is subsequently used to categorize the dust weather. The satellite-derived spatial frequency distributions in the dust weather types are consistent with China s weather station reports during 2003, indicating that dust weather classification using satellite data is highly feasible. Although the period during the springtime from 2004 to 2007 may be not sufficient for statistical significance, our results reveal an increasing tendency in both intensity and frequency of dust weather over central Asia during this time period.

Lin, Tang-Huang; Hsu, N. Christina; Tsay, Si-Chee; Huang, Shih-Jen

2011-01-01

2

Revised Uniform Summary of Surface Weather Observations, Incirlik Air Base, Turkey. Parts A-F.  

National Technical Information Service (NTIS)

A six-part statistical data summary of surface weather observation for: Incirlik, AB Turkey. Summary consists of: PART A, Weather Conditions and Atmospheric Phenomena; PART B, Precipitation; PART C, Surface Winds; PART D, Ceiling and Visibility; PART E, P...

1987-01-01

3

Revised Uniform Summary of Surface Weather Observations (RUSSWO) - Osan AB, Osan-Ni, Korea.  

National Technical Information Service (NTIS)

This six-part statistical summary of surface weather observations for Osan AB, Osan-Ni, Korea contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (C) S...

1978-01-01

4

Osan AB, Korea. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Osan AB, Korea. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values)...

1982-01-01

5

Fairford RAF, Swindon, United Kingdom. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

This report is a six-part statistical summary of surface weather observations for Fairford RAF, Swindon, United Kingdom. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amou...

1979-01-01

6

Abrupt Seasonal Changes of Surface Climate Observed in Northern Mongolia by an Automatic Weather Station  

Microsoft Academic Search

Continuous observations of surface meteorological elements have been carried out since September 30, 1993, to study the roles of land surface processes in seasonal climate variation. The observations were taken by the AANDERA Automatic Weather Station (AWS) at Baruunkharaa (48°55?N, 106°4?E) in northern Mongolia. This location is the center of the source region of the Siberian high, which is a

Shin Miyazaki; Tetsuzo Yasunari; T A

1999-01-01

7

On Observing the Weather  

NSDL National Science Digital Library

In this article, Mount Washington Observatory meteorologist Tim Markle shares the ins and outs of his daily weather-observing routine and offers insights on making weather observations at home or at school.

Crane, Peter

2004-05-01

8

Arctic Weather Change: Linking Indigenous (Inuit) Observations With the Surface Temperature Record  

NASA Astrophysics Data System (ADS)

Inuit observations in the Artic describe increasing unpredictability in the weather. In an effort to link their reports with scientific data, we analyzed time series of surface temperatures from two stations; Baker Lake and Clyde River, located in Nunavut, Canada. 52 year records (1953-2004) of hourly WMO weather station temperature data were utilized for a statistical assessment at the two locations. Large positive trends in mean temperature were observed at both sites. Hourly and daily temperature differences were then calculated noting that a positive tendency in results may be indicative of recent variability. This was not seen. Further examination focused on a possible increase or decrease in frontal activity; these results displayed little change in the magnitude of frontal activity in both locations. Very small changes were observed in the variance, with a tendency toward higher values. It is difficult to understand how these small changes in variance could be easily observable by the Inuit, although the ramification of a small change in variance may be more easily observed. Finally, day-to-day autocorrelation was calculated as a way to quantify the persistence of weather. A strong change was noted in June at Baker Lake. At the beginning of the time series (1953 - 1990) autocorrelation values were typically in the 0.8 +- 0.1 range, in the 1990's they were often around 0.4. These results show a marked change in the persistence of weather for this month. We will need to explore further if such an outcome can be used to estimate the predictability of weather and estimate changes in weather patterns. These initial results, however, are promising and point to a distinct change in the nature and predictability of weather.

Noonan, G. J.; Weatherhead, E. C.; Gearheard, S.; Barry, R.

2005-12-01

9

National Weather Service Observing Handbook No. 1: Marine Surface Weather Operations.  

National Technical Information Service (NTIS)

In writing this new edition of NWS Observing Handbook No. 1, it has been our intent to include as much useful information as possible in the available space. The compact size and design, and field guide format, should allow for easy handling and quick ref...

2004-01-01

10

Seymour Johnson AFB, North Carolina Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.  

National Technical Information Service (NTIS)

A six-part statistical data summary of surface observation climatology for: Seynour Johnson AFB, North Carolina. Summary consists of: Part A, Weather Conditions and Atmospheric Phenomena; Part B, Precipitation; Part C, Surface Winds; Part D, Ceiling and V...

1985-01-01

11

On Observing the Weather  

ERIC Educational Resources Information Center

Rain, sun, snow, sleet, wind... the weather affects everyone in some way every day, and observing weather is a terrific activity to attune children to the natural world. It is also a great way for children to practice skills in gathering and recording information and to learn how to use simple tools in a standardized fashion. What better way to…

Crane, Peter

2004-01-01

12

A revised empirical model to estimate solar radiation using automated surface weather observations  

Microsoft Academic Search

The transition from manual to automated weather observations at US National Weather Service Offices has compromised the ability to use these data as a means for estimating global horizontal and direct solar radiation. The creation of long term model-derived solar radiation climatologies continues to rely on the in situ cloud data that these observations provide, since homogeneous and readily available

Brian N. Belcher; Arthur T. DeGaetano

2007-01-01

13

Recovery of Global Surface Weather Observations for Historical Reanalyses and International Users  

NASA Astrophysics Data System (ADS)

Third International Atmospheric Circulation Reconstructions Over the Earth Initiative Workshop: Reanalysis and Applications; Baltimore, Maryland, 3-5 November 2010 ; The third Atmospheric Circulation Reconstructions over the Earth (ACRE) workshop advanced the goals of the international ACRE initiative (http://www.met-acre.org/) to undertake and facilitate the recovery of instrumental terrestrial and marine global surface weather observations underpinning global weather reconstructions and reanalyses spanning the past 200-250 years (http://reanalyses.org). The workshop improved integration of the 35-40 ACRE-linked international scientific projects, institutions, and organizations working toward these ends. The meeting highlighted the broad array and international usage of ACRE-facilitated data sets and reanalysis: the International Surface Pressure Databank (ISPD; http://dss.ucar.edu/datasets/ds132.0/), the International Comprehensive Ocean-Atmosphere Data Set (http:/icoads.noaa.gov/ICOADS;), and the 20th Century Reanalysis (20CR; http://www.esrl.noaa.gov/psd/data/20thC_Rean/). The need for more data recovery for all regions of the globe during the nineteenth and early twentieth centuries was emphasized. Many regional efforts for such recovery are under way. The Arctic and maritime regions were highlighted as particular areas needing attention. As a result of the meeting, connections with existing projects were made and new efforts were started to address these needs.

Allan, Rob; Compo, Gil; Carton, Jim

2011-05-01

14

Incipient Space Weathering Observed on the Surface of Itokawa Dust Particles  

NASA Astrophysics Data System (ADS)

The reflectance spectra of the most abundant meteorites, ordinary chondrites, are different from those of the abundant S-type (mnemonic for siliceous) asteroids. This discrepancy has been thought to be due to space weathering, which is an alteration of the surfaces of airless bodies exposed to the space environment. Here we report evidence of space weathering on particles returned from the S-type asteroid 25143 Itokawa by the Hayabusa spacecraft. Surface modification was found in 5 out of 10 particles, which varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles exist in a thin (5 to 15 nanometers) surface layer on olivine, low-Ca pyroxene, and plagioclase, which is suggestive of vapor deposition. Sulfur-free Fe-rich nanoparticles exist deeper inside (<60 nanometers) ferromagnesian silicates. Their texture suggests formation by metamictization and in situ reduction of Fe2+.

Noguchi, T.; Nakamura, T.; Kimura, M.; Zolensky, M. E.; Tanaka, M.; Hashimoto, T.; Konno, M.; Nakato, A.; Ogami, T.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

2011-08-01

15

Incipient space weathering observed on the surface of Itokawa dust particles.  

PubMed

The reflectance spectra of the most abundant meteorites, ordinary chondrites, are different from those of the abundant S-type (mnemonic for siliceous) asteroids. This discrepancy has been thought to be due to space weathering, which is an alteration of the surfaces of airless bodies exposed to the space environment. Here we report evidence of space weathering on particles returned from the S-type asteroid 25143 Itokawa by the Hayabusa spacecraft. Surface modification was found in 5 out of 10 particles, which varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles exist in a thin (5 to 15 nanometers) surface layer on olivine, low-Ca pyroxene, and plagioclase, which is suggestive of vapor deposition. Sulfur-free Fe-rich nanoparticles exist deeper inside (<60 nanometers) ferromagnesian silicates. Their texture suggests formation by metamictization and in situ reduction of Fe(2+). PMID:21868670

Noguchi, T; Nakamura, T; Kimura, M; Zolensky, M E; Tanaka, M; Hashimoto, T; Konno, M; Nakato, A; Ogami, T; Fujimura, A; Abe, M; Yada, T; Mukai, T; Ueno, M; Okada, T; Shirai, K; Ishibashi, Y; Okazaki, R

2011-08-26

16

Subgrid Surface Fluxes in Fair Weather Conditions during TOGA COARE: Observational Estimates and Parameterization  

Microsoft Academic Search

Bulk aerodynamic formulas are applied to meteorological data from low-altitude aircraft flights to obtain observational estimates of the subgrid enhancement of momentum, sensible heat, and latent heat exchange at the atmospheric-oceanic boundary in light wind, fair weather conditions during TOGA COARE (Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment). Here, subgrid enhancement refers to the contributions of unresolved disturbances to

Dean Vickers; Steven K. Esbensen

1998-01-01

17

Observations of “fresh” and weathered surfaces on asteroid pairs and their implications on the rotational-fission mechanism  

NASA Astrophysics Data System (ADS)

The rotational-fission of a “rubble-pile” structured asteroid can result in an “asteroid pair” - two unbound asteroids sharing nearly identical heliocentric orbits. Models suggest that this mechanism exposes material from below the progenitor surface that previously had never have been exposed to the weathering conditions of space. Therefore, the surfaces of asteroid pairs offer the opportunity to observe non-weathered “fresh” spectra. Here we report near-infrared spectroscopic observations of 31 asteroids in pairs. In order to search for spectral indications of fresh surfaces we analyze their spectral slopes, parameters of their 1 ?m absorption band and taxonomic classification. Additionally, through backward dynamical integration we estimate the time elapsed since the disintegration of the pairs’ progenitors. Analyzing the 19 ordinary chondrite-like (S-complex) objects in our sample, we find two Q-type Asteroids (19289 and 54827) that are the first of their kind to be observed in the main-belt of asteroids over the full visible and near-infrared range. This solidly demonstrates that the Q-type taxonomy is not limited to the NEA population. The pairs in our sample present a range of fresh and weathered surfaces with no clear evidence for a correlation with the ages of the pairs. However, our sample includes “old” pairs (2 × 106 ? age ? 1 × 106 years) that present relatively low, meteoritic-like spectral slopes (<0.2% per ?m). This illustrates a timescale of at least ?2 myr before an object develops high spectral slope that is typical for S-type asteroids. We discuss three mechanisms that explain the existence of weathered pairs with young dynamical ages and find that the “secondary fission” model (Jacobson, S.-A., Scheeres, D.-J. [2011]. Icarus 214, 161-178) is the most robust with our observations. In this mechanism an additional and subsequent fission of the secondary component contributes the lion share of fresh material that re-settles on the primary’s surface and recoats it with fresh material. If the secondary breaks loose from the vicinity of the primary before its “secondary fission”, this main source of fresh dust is avoided. We prefer this secondary fission model since (i) the secondary members in our sample present “fresh” parameters that tend to be “fresher” than their weathered primaries; (ii) most of the fresh pairs in our sample have low size ratios between the secondary and the primary; (iii) 33% of the primaries in our sample are fresh, similar to the prediction set by the secondary fission model (Jacobson, S.-A., Scheeres, D.-J. [2011]. Icarus 214, 161-178); (iv) known satellites orbit two of the pairs in our sample with low size ratio (D2/D1) and fresh surface; (v) there is no correlation between the weathering state and the primary shape as predicted by other models.

Polishook, David; Moskovitz, Nicholas; Binzel, Richard P.; DeMeo, Francesca E.; Vokrouhlický, David; Žižka, Jind?ich; Oszkiewicz, Dagmara

2014-05-01

18

Statistics of link blockage due to cloud cover for free-space optical communications using NCDC surface weather observation data  

NASA Astrophysics Data System (ADS)

Cloud opacity is one of the main atmospheric physical phenomena that can jeopardize the successful completion of an optical link between a spacecraft and a ground station. Hence, the site location chosen for a telescope used for optical communications must rely on knowledge of weather and cloud cover statistics for the geographical area where the telescope itself is located. In this work, the effects of cloud cover on an optical link are statistically described, considering ten observation sites at locations in the southwestern United States, From California to Texas. The data used for the preparation of this work are surface observation data provided by the National Climatic Data Center (NCDC). NCDC provides hourly information on the cloud coverage of an observation site. Using proper algorithms, these data give a statistical description of link blockage over the ten selected observations sites. Statistics averaged over a number of years for each observation site are presented. Cloud coverage statistics for two and three site diversity are also given for a ground network of optical telescopes. Finally, it is shown quantitatively how the use of two or three telescopes can improve the probability of completion of an optical link and how to select the right locations for a ground network of telescopes in the southwestern United States.

Piazzolla, Sabino; Slobin, Stephen

2002-04-01

19

Martian surface weathering studies  

NASA Technical Reports Server (NTRS)

The nature of the Martian surface was characterized by means of its reflectance properties. The Mariner 9 photography was used to establish terrain units which were crossed by the Mariner 6 and 7 paths. The IR reflectance measured by the IR spectrometers on these spacecraft was to be used to indicate the nature of the surface within these units. There is an indication of physical size and/or compositional variation between units but too many natural parameters can vary (size, shape, composition, adsorbed phases, reradiation, atmospheric absorbtion, temperature gradients, etc.) to be certain what effect is causing those variations observed. It is suggested that the characterization could be fruitfully pursued by a group which was dedicated to peeling back the layers of minutia affecting IR reflectance.

Calvin, M.

1973-01-01

20

The potential of QuikSCAT and WindSat observations for the estimation of sea surface wind vector under severe weather conditions  

Microsoft Academic Search

The physics of remote sensing sea surface measurements is still poorly understood under severe weather conditions. Wind vector algorithms are usually developed for non-precipitating atmospheres and for wind speeds less than 20 m\\/s. In this study, we analyze observations from the QuikSCAT Ku-band scatterometer collocated with the WindSat full polarimetric microwave radiometer to estimate the potential of these two instruments

Y. Quilfen; C. Prigent; B. Chapron; A. A. Mouche; N. Houti

2007-01-01

21

Earth Observation Services Weather Imaging  

NASA Technical Reports Server (NTRS)

Microprocessor-based systems for processing satellite data offer mariners real-time images of weather systems, day and night, of large areas or allow them to zoom in on a few square miles. Systems West markets these commercial image processing systems, which have significantly decreased the cost of satellite weather stations. The company was assisted by the EOCAP program, which provides government co-funding to encourage private investment in, and to broaden the use of, NASA-developed technology for analyzing information about Earth and ocean resources.

1992-01-01

22

Statistics of link blockage due to cloud cover for free-space optical communications using NCDC surface weather observation data  

NASA Technical Reports Server (NTRS)

Cloud opacity is one of the main atmospheric physical phenomena that can jeopardize the successful completion of an optical link between a spacecraft and a ground station. Hence, the site location chosen for a telescope used for optical communications must rely on knowledge of weather and cloud cover statistics for the geographical area where the telescope itself is located.

Slobin, S. D.; Piazzolla, S.

2002-01-01

23

Statistics of link blockage due to cloud cover for free-space optical communications using NCDC surface weather observation data  

Microsoft Academic Search

Cloud opacity is one of the main atmospheric physical phenomena that can jeopardize the successful completion of an optical link between a spacecraft and a ground station. Hence, the site location chosen for a telescope used for optical communications must rely on knowledge of weather and cloud cover statistics for the geographical area where the telescope itself is located. In

Sabino Piazzolla; Stephen D. Slobin

2002-01-01

24

Methods to Estimate Surface Fluxes of Momentum and Heat from Routine Weather Observations for Dispersion Applications under Stable Stratification  

NASA Astrophysics Data System (ADS)

We examine the efficacy of two methods commonly used to estimate the vertical turbulent fluxes of momentum and sensible heat from routinely observed mean quantities in the surface layer under stable stratification. The single-level method uses mean wind speed and temperature measurements at a single height, whereas the two-level method uses mean wind speed measurements at a single height and mean temperature measurements at two heights. These methods are used in popular meteorological processors such as the U.S. Environmental Protection Agency approved AERMET and CALMET to generate inputs for dispersion simulations. We use data from a flux station of the U.K. Met Office at Cardington for comparison. It is found that the single-level method does not describe the flux variation in the weakly stable regime at all, because of its assumption that the temperature scale, i.e. the ratio of the kinematic sensible heat flux to the friction velocity, is constant, which is plausible only under strongly stable conditions. On the other hand, the two-level method provides a physically realistic variation of the fluxes with stability, but the required temperature measurements at two levels are usually not available on a routine basis. If measurements of the standard deviation of temperature are also available, in addition to the mean temperature at a single level, then they can be usefully employed in a third (single-level) method, with the consequence that the computed fluxes are very similar to those obtained from the two-level method. An improvement to the original single-level method is considered, and flux calculations under low wind conditions are also discussed.

Luhar, Ashok K.; Rayner, Ken N.

2009-09-01

25

Surface mass-balance observations and automatic weather station data along a transect near Kangerlussuaq, West Greenland  

Microsoft Academic Search

Surface mass-balance data from the Kangerlussuaq transect (K-transect) located on the western part of the Greenland ice sheet near 678 N are presented. The series covers the period 1990- 2003 and is the longest series of surface mass-balance measurements in Greenland. The surface mass- balance measurements cover an altitude range of 390-1850 m and show a linear increase of the

W. Greuell; M. R. van den Broeke; C. H. Reijmer; J. Oerlemans

2005-01-01

26

Surface mass-balance observations and automatic weather station data along a transect near Kangerlussuaq, West Greenland  

Microsoft Academic Search

Surface mass-balance data from the Kangerlussuaq transect (K-transect) located on the western part of the Greenland ice sheet near 67° N are presented. The series covers the period 1990-2003 and is the longest series of surface mass-balance measurements in Greenland. The surface massbalance measurements cover an altitude range of 390-1850 m and show a linear increase of the specific mass

W. Greuell; M. R. van den Broeke; C. H. Reijmer; J. Oerlemans

2005-01-01

27

Anomaly patterns about strong convective events in the tropics and midlatitudes: Observations from radiosondes and surface weather stations  

NASA Astrophysics Data System (ADS)

use 13 years (1998-2010) of rainfall estimates from the Tropical Rainfall Measuring Mission to identify high rain events located close to radiosondes. This is done in four regions: the Western Tropical Pacific, Tropical Brazil, Southeast China, and Southeast U.S. We then construct composite anomaly patterns of temperature, relative humidity, surface pressure, convective available potential energy (CAPE), geopotential height, mass divergence, relative vorticity, and potential vorticity about these high rain events. One motivation of this analysis is to identify regional differences in the interaction between strong convective events and the background atmosphere. We find, overall, that the changes in meteorological variables which occur during the evolution of strong convective events in midlatitudes are similar to the changes that occur in the tropics. In midlatitudes, however, strong convective events are associated with stronger anomalies in surface pressure and geopotential height and exhibit a warm anomaly in the lower troposphere prior to peak rainfall. In the Southeast U.S., the near-surface layer of positive CAPE that occurs prior to high rain events is thicker than in the Western Tropical Pacific. In the two midlatitude regions, the midlevel potential vorticity maximum that develops during the growth stage of high rain events acquires a downward tilt toward the surface during the decay stage, suggesting downward transport toward the surface. A conceptual model previously used to interpret the anomaly patterns of the 2 day equatorial wave is used to interpret the anomaly patterns associated with more general types of high rain events in the tropics.

Mitovski, Toni; Folkins, Ian

2014-01-01

28

Observations of the radiation divergence in the surface layer and its implication for its parameterization in numerical weather prediction models  

Microsoft Academic Search

This paper presents the results of 5 months of in situ observations of the diurnal cycle of longwave radiative heating rate in the lower part of the atmospheric boundary layer over grassland, with a particular focus on nighttime conditions. The observed longwave radiative heating is minimal at the evening transition, with a median value of ?1.8 K h?1 between 1.3

G. J. Steeneveld; M. J. J. Wokke; C. D. Groot Zwaaftink; S. Pijlman; B. G. Heusinkveld; A. F. G. Jacobs; A. A. M. Holtslag

2010-01-01

29

Regional chemical weather forecasting system CFORS: Model descriptions and analysis of surface observations at Japanese island stations during the ACE-Asia experiment  

Microsoft Academic Search

The Chemical Weather Forecast System (CFORS) is designed to aid in the design of field experiments and in the interpretation\\/postanalysis of observed data. The system integrates a regional chemical transport model with a multitracer, online system built within the Regional Atmospheric Modeling System (RAMS) mesoscale model. CFORS was deployed in forecast and postanalysis modes during the NASA Global Tropospheric Experiment

I. Uno; G. R. Carmichael; D. G. Streets; Y. Tang; J. J. Yienger; S. Satake; Z. Wang; Jung-Hun Woo; S. Guttikunda; M. Uematsu; K. Matsumoto; H. Tanimoto; K. Yoshioka; T. Iida

2003-01-01

30

Weather observations through oceanic acoustic noise recorded by gliders  

NASA Astrophysics Data System (ADS)

Offshore estimates of the meteorological parameters are unfortunately spurious when considering in-situ observtions only due to obvious observational limitations while their use would allow to calibrate satellite observations and to have better weather forecasts, if assimilated in numerical weather forecasting systems. The WOTAN (Weather Observations through Acoustic Noise) approach may be used to fill these gaps if coupled to the Global Ocean Observing Sytem which has now a global coverage thanks to many autonomous observing platforms. In this study we show first results from acoustic records collected by gliders deployed in the northwestern Mediterranean Sea in the framework of MOOSE. We show that using 3 descriptors at 5kHz, 8kHz, and 20kHz allows to extract the intensity of the wind and the precipitation when the glider is at depth. This approach based on the method presented by Barry & Nuysten (2004) is compared with meterological data from coastal weather stations and the offshore meteorological buoys from Meteo-France. We also show that there is a vane effect with the tail of the glider while at surface which allows to estimate the direction of the wind every so often. These observations coupled with the in-situ profiles on temperature and salinity profiles can allow to better study air-sea interactions.

Cauchy, Pierre; Testor, Pierre; Guinet, Christophe; Gervaise, Cedric; Di Oro, Lucia; Ioana, Cornel; Mortier, Laurent; Bouin, Marie-Noelle; Beguery, Laurent; Klein, Patrice

2013-04-01

31

Rates of oxidative weathering on the surface of Mars  

NASA Technical Reports Server (NTRS)

Implicit in the mnemonic 'MSATT' (Mars surface and atmosphere through time) is that rates of surface processes on Mars through time should be investigated, including studies of the kinetics and mechanism of oxidative weathering reactions occurring in the Martian regolith. Such measurements are described. Two major elements analyzed in the Viking Lander XRF experiment that are most vulnerable to atmospheric oxidation are iron and sulfur. Originally, they occurred as Fe(2+)-bearing silicate and sulfide minerals in basaltic rocks on the surface of Mars. However, chemical weathering reactions through time have produced ferric- and sulfate-bearing assemblages now visible in the Martian regolith. Such observations raise several question about: (1) when the oxidative weathering reactions took place on Mars; (2) whether or not the oxidized regolith is a fossilized remnant of past weathering processes; (3) deducting chemical interactions of the ancient Martian atmosphere with its surface from surviving phases; (4) possible weathering reactions still occurring in the frozen regolith; and (5) the kinetics and mechanism of past and present-day oxidative reactions on Mars. These questions may be addressed experimentally by studying reaction rates of dissolution and oxidation of basaltic minerals, and by identifying reaction products forming on the mineral surfaces. Results for the oxidation of pyrrhotite and dissolved ferrous iron are reported.

Burns, Roger G.

1992-01-01

32

Rates of oxidative weathering on the surface of Mars  

NASA Astrophysics Data System (ADS)

Implicit in the mnemonic 'MSATT' (Mars surface and atmosphere through time) is that rates of surface processes on Mars through time should be investigated, including studies of the kinetics and mechanism of oxidative weathering reactions occurring in the Martian regolith. Such measurements are described. Two major elements analyzed in the Viking Lander XRF experiment that are most vulnerable to atmospheric oxidation are iron and sulfur. Originally, they occurred as Fe(2+)-bearing silicate and sulfide minerals in basaltic rocks on the surface of Mars. However, chemical weathering reactions through time have produced ferric- and sulfate-bearing assemblages now visible in the Martian regolith. Such observations raise several question about: (1) when the oxidative weathering reactions took place on Mars; (2) whether or not the oxidized regolith is a fossilized remnant of past weathering processes; (3) deducting chemical interactions of the ancient Martian atmosphere with its surface from surviving phases; (4) possible weathering reactions still occurring in the frozen regolith; and (5) the kinetics and mechanism of past and present-day oxidative reactions on Mars. These questions may be addressed experimentally by studying reaction rates of dissolution and oxidation of basaltic minerals, and by identifying reaction products forming on the mineral surfaces. Results for the oxidation of pyrrhotite and dissolved ferrous iron are reported.

Burns, Roger G.

33

Widespread Surface Weathering on Early Mars  

NASA Astrophysics Data System (ADS)

The recent discovery of widespread hydrous clays on Mars indicates that diverse and widespread aqueous environments existed on Mars, from the surface to kilometric depths [1,2]. The study of the past habitability of the planet requires assessing the importance of sustained surface water vs. subsurface water in its aqueous history. Using remote sensing data, we propose that surface weathering existed on Mars, suggesting that Mars experienced durable episodes of sustained liquid water on its surface. Weathering profiles are identified as vertical sequences of Al-rich clays and Fe/Mg-rich clays in the top tens of meters of the surface, similar to cases of pedogenesis on Earth (e.g. [3,4]). Such localized clay sequences have been reported by other works in 3 regions of Mars [5-8] and a similar origin was also proposed. Their frequency is however likely underestimated due to limitations of orbital investigations and re-surfacing processes. A large survey of the CRISM dataset leaded to a down-selection of 104 deposits with clear vertical sequences, widely distributed over the southern highlands and grouped in regional clusters [9]. These putative weathering sequences are found either on inter-crater plateaus, on the floor of craters and large basins, or on crater ejectas. We investigated the thickness of the altered sequences, the age of the altered units and the different geological contexts to further understand the weathering process(es). Using few HiRISE DEMs where possible, and CTX DEMs, we find that the thickness of the exposed Al clays is on average of the order of several meters to few tens of meters. The clay sequences reported here are consistent with terrestrial weathering sequences which form under wet climates over geological timescales (> 105-107 years). The combined age assessment of the altered unit and the unaltered capping (where present) provides constraints on the age of the weathering itself. All investigated cases point to an active weathering limited to the late Noachian to early Hesperian. The widespread distribution of weathering sequences in different geologic contexts, and the consistency in their estimated ages are best explained if Mars experienced a period/periods between the middle Noachian and the early Hesperian during which climatic conditions allowed sustained liquid water flow on its surface, while the high degree of degradation of older terrains does not allow affirming nor infirming earlier surface weathering on Mars. Only the in-situ exploration of Phyllosian/Noachian terrains may provide an answer to this fundamental question. Some of the authors have received funding from the European Research Council (FP7/2007-2013)/ERC Grant agreement n° 280168. [1] Ehlmann B., et al. Nature, 479, 53-60 (2011). [2] Carter J., et al. JGR, 118, 831-858 (2013) [3] Velde B., et al. Ed. Springer, Berlin, (1995). [4] Wilson M. Clay Minerals, 39, 233-266 (2004). [5] Gaudin A., et al. Icarus, 216(1), 257-268 (2011). [6] Loizeau D., et al. Icarus, 205, 396-418 (2010). [7] Noe Dobrea E., et al. JGR, 115, E00D19 (2010). [8] Le Deit L., et al. JGR, 117, E00J05 (2012). [9] Carter J., et al. LPSC 2012, p.1755

Loizeau, D.; Carter, J.; Mangold, N.; Poulet, F.; Rossi, A.; Allemand, P.; Quantin, C.; Bibring, J.

2013-12-01

34

Widespread Surface Weathering on Early Mars  

NASA Astrophysics Data System (ADS)

The recent discovery of widespread hydrous clays on Mars indicates that diverse and widespread aqueous environments existed on Mars, from the surface to kilometric depths [1,2]. The study of the past habitability and past climates of the planet requires assessing the importance of sustained surface water vs. subsurface water in its aqueous history. Using remote sensing data, we propose that surface weathering existed on Mars, suggesting that Mars experienced durable episodes of sustained liquid water on its surface. Weathering profiles are identified as vertical sequences of Al-rich clays and Fe/Mg-rich clays in the top tens of meters of the surface, similar to cases of pedogenesis on Earth (e.g. [3,4]). Such localized clay sequences have been reported by other works in 3 regions of Mars [5-8] and a similar origin was also proposed. Their frequency is however likely underestimated due to limitations of orbital investigations and re-surfacing processes. A large survey of the CRISM dataset leaded to a down-selection of ~100 deposits with clear vertical sequences, widely distributed over the southern highlands and grouped in regional clusters [9]. These putative weathering sequences are found either on inter-crater plateaus, on the floor of craters and large basins, or on crater ejectas. We investigated the thickness of the altered sequences, the age of the altered units and the different geological contexts to further understand the weathering process(es). Using few HiRISE DEMs where possible, and CTX DEMs, we find that the thickness of the exposed Al clays is on average of the order of several meters to few tens of meters. The clay sequences reported here are consistent with terrestrial weathering sequences which form under wet climates over geological timescales (>105-107 years). The combined age assessment of the altered unit and the unaltered capping (where present) provides constraints on the age of the weathering itself. All investigated cases point to an active weathering limited to the late Noachian to early Hesperian. The widespread distribution of weathering sequences in different geologic contexts, and the consistency in their estimated ages are best explained if Mars experienced a period/periods between the middle Noachian and the early Hesperian during which climatic conditions allowed sustained liquid water flow on its surface, while the high degree of degradation of older terrains does not allow affirming nor infirming earlier surface weathering on Mars. Only the in-situ exploration of Phyllosian/Noachian terrains may provide an answer to this fundamental question. Some of the authors have received funding from the ERC (FP7/2007-2013)/ERC Grant agreement n° 280168. [1] Ehlmann B., et al. Nature, 479, 53-60 (2011). [2] Carter J., et al. JGR, 118, 831-858 (2013) [3] Velde B., et al. Ed. Springer, Berlin, (1995). [4] Wilson M. Clay Minerals, 39, 233-266 (2004). [5] Gaudin A., et al. Icarus, 216(1), 257-268 (2011). [6] Loizeau D., et al. Icarus, 205, 396-418 (2010). [7] Noe Dobrea E., et al. JGR, 115, E00D19 (2010). [8] Le Deit L., et al. JGR, 117, E00J05 (2012). [9] Carter J., et al. LPSC 2012, p.1755

Loizeau, Damien; Carter, John; Mangold, Nicolas; Poulet, François; Rossi, Angelo; Allemand, Pascal; Quantin, Cathy; Bibring, Jean-Pierre

2014-05-01

35

Automation of surface observations program  

NASA Technical Reports Server (NTRS)

At present, surface weather observing methods are still largely manual and labor intensive. Through the nationwide implementation of Automated Surface Observing Systems (ASOS), this situation can be improved. Two ASOS capability levels are planned. The first is a basic-level system which will automatically observe the weather parameters essential for aviation operations and will operate either with or without supplemental contributions by an observer. The second is a more fully automated, stand-alone system which will observe and report the full range of weather parameters and will operate primarily in the unattended mode. Approximately 250 systems are planned by the end of the decade. When deployed, these systems will generate the standard hourly and special long-line transmitted weather observations, as well as provide continuous weather information direct to airport users. Specific ASOS configurations will vary depending upon whether the operation is unattended, minimally attended, or fully attended. The major functions of ASOS are data collection, data processing, product distribution, and system control. The program phases of development, demonstration, production system acquisition, and operational implementation are described.

Short, Steve E.

1988-01-01

36

Initialisation of Land Surface Variables for Numerical Weather Prediction  

NASA Astrophysics Data System (ADS)

Land surface processes and their initialisation are of crucial importance for Numerical Weather Prediction (NWP). Current land data assimilation systems used to initialise NWP models include snow depth analysis, soil moisture analysis, soil temperature and snow temperature analysis. This paper gives a review of different approaches used in NWP to initialise land surface variables. It discusses the observation availability and quality, and it addresses the combined use of conventional observations and satellite data. Based on results from the European Centre for Medium-Range Weather Forecasts (ECMWF), results from different soil moisture and snow depth data assimilation schemes are shown. Both surface fields and low-level atmospheric variables are highly sensitive to the soil moisture and snow initialisation methods. Recent developments of ECMWF in soil moisture and snow data assimilation improved surface and atmospheric forecast performance.

de Rosnay, Patricia; Balsamo, Gianpaolo; Albergel, Clément; Muñoz-Sabater, Joaquín; Isaksen, Lars

2014-05-01

37

Observing Space Weather towards building Predictive Capabilities  

NASA Astrophysics Data System (ADS)

Simultaneous data from multi-point space missions operating in the Sun-Earth system in conjunction with dedicated ground- based networks have facilitated major steps towards the quantification of space weather processes, better understandings of their impacts on the various high level systems of modern societal infrastructure and fundamental developments in space weather forecasting. Through the EU FP7 program and the ESA Space Situational Awareness (SSA) program several dedicated space weather projects and studies have currently been initiated, such as the AFFECTS (Advanced Forecast For Ensuring Communications Through Space), aiming in establishing prototype space weather services, instruments and missions as precursors of a future space weather operational system. This presentation provides an overview of the ongoing European activities, upcoming challenges and opportunities for international collaborations.

Bothmer, Volker

2012-07-01

38

Weather  

NSDL National Science Digital Library

You will learn how to describe and observe changes in weather patterns by completing the following activities. The students will record and report changes in weather on their data sheet. The Process: Read the information on How Air Pressure Affects You. In this article you will see the term barometer. Write its definition. Now look over Weather Facts. Now go to Investigate Climate Conditions and use the weather maker to observe the effects of certain changes. Answer the questions: How much of a change in temperature is needed to make it ...

Lauren, Ms.

2010-11-17

39

Summary of Meteorological Observations, Surface (SMOS), Cecil Field, FL.  

National Technical Information Service (NTIS)

This data report consists of a six part statistical summary of surface weather observations. The six parts are: Part A - Weather Conditions/Atmospheric Phenomena, Part B - Precipitation/Snowfall/Snow Depth, Part C - Surface Winds, Part D - Ceiling versus ...

1978-01-01

40

Easter Island, Chile Limited Surface Observations Climatic Summary (LISOCS). Parts A, C-F.  

National Technical Information Service (NTIS)

A statistical data summary of surface weather observation climatology for: Easter Island Chile. This summary is similar to the Revised Uniform Summary of Surface Weather Observations (RUSSWO), but is based on data collected from limited-duty weather obser...

1985-01-01

41

Observe the effects of mechanical weathering  

NSDL National Science Digital Library

In this interactive Earth science resource, students are first presented with six photographs, each featuring a different mechanical weathering event in which rock is broken down. Examples of the events include road damage due to ice heaving and the expansion of cracks in rocks due to tree growth. Students are instructed to click on each labeled image to see an enlarged version of it. In the enlarged view, brief text, often accompanied by visual cues such as arrows, explains the physical weathering process shown. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

42

Stepwise Onset of Monsoon Weather Observed in the Nepal Himalaya  

Microsoft Academic Search

Mountain weather changes in the Nepal Himalaya were intensively examined during the 2003 monsoon onset using in situ datasets, observed by multiple automatic weather stations (AWS) distributed across the Coordinated Enhanced Observing Period (CEOP) Himalaya reference site at locations with significant differences in altitude. Onset of monsoon rainfall characterized as nighttime precipitation was initiated simultaneously at all stations with the

K. Ueno; K. Toyotsu; L. Bertolani; G. Tartari

2008-01-01

43

SMEI Observations and Space Weather Forecasting  

Microsoft Academic Search

CMEs are a primary cause of severe space weather at Earth because they trigger geomagnetic storms that damage space and ground-based assets. The Solar Mass Ejection Imager (SMEI) is a U. S. Air Force experiment whose primary purpose is to demonstrate the ability to track CMEs from near the Sun to Earth, thus providing a new capability for forecasting storms.

D. Webb; T. Howard; J. Johnston; C. Fry

2006-01-01

44

Observation impact on forecast parameters of mesoscale weather systems  

NASA Astrophysics Data System (ADS)

The sensitivity of forecast outputs to observational inputs is quantified by utilizing the adjoint formulations of a numerical weather prediction model and data assimilation system. The reduction in short term forecast error due to the assimilation of observations is investigated using a limited area model with horizontal grid spacings appropriate for mesoscale weather systems. The relative impact of observations can vary greatly depending on the physical location of the model's domain and the area over which the error is calculated. For example, observations from radiosondes and aircraft are important for reducing error over the eastern United States, but satellite derived winds and surface reports over the eastern Pacific Ocean are most important if the target area is over the western US. There are subtle differences in the observation impacts on forecasts utilizing a range of horizontal grid spacings (20-60 km). In a few cases for the smaller grid spacings, the adjoint of the limited area model fails to account for a satisfactory amount of the nonlinear model error. Impacts on metrics other than forecast error will also be presented.

Amerault, C. M.

2011-12-01

45

Standardisation of Temperature Observed by Automatic Weather Stations  

Microsoft Academic Search

Daily mean, maximum and minimum surface airtemperature data were gathered from a network ofautomatic weather stations (AWS) within the Moor HouseNational Nature Reserve in northern England. Five AWSwere installed next to the official EnvironmentalChange Network weather station at Moor House. Datawere compared graphically and correction constantswere calculated to adjust data from each AWS to thestandard of the official station by

A. Joyce; J. Adamson; B. Huntley; T. Parr; R. Baxter

2001-01-01

46

Automated surface observing systems  

NSF Publications Database

Title : Automated surface observing systems Type : Antarctic EAM NSF Org: OD / OPP Date : August 19 ... Action Memorandum (Installation of Automated Surface Observing Systems [ASOS}) To: Director, Office ...

47

Surface Landing Site Weather Analysis for Constellation Program  

NASA Technical Reports Server (NTRS)

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is an important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface atmospheric conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. Climatological time series of operational surface weather observations are used to calculate probabilities of occurrence of various sets of hypothetical vehicle constraint thresholds, Data are available for numerous geographical locations such that statistical analysis can be performed for single sites as well as multiple-site network configurations. Results provide statistical descriptions of how often certain weather conditions are observed at the site(s) and the percentage that specified criteria thresholds are matched or exceeded. Outputs are tabulated by month and hour of day to show both seasonal and diurnal variation. This paper will describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that can be obtained,

Altino, Karen M.; Burns, K. Lee

2008-01-01

48

Evidence of Space Weathering Processes Across the Surface of Vesta  

NASA Astrophysics Data System (ADS)

As NASA's Dawn spacecraft explores the surface of Vesta, it has become abundantly clear that Vesta is like no other planetary body visited to date. Dawn is collecting global data at increasingly higher spatial resolution during its one-year orbital mission. The bulk properties of Vesta have previously been linked to the HED meteorites through remote mineral characterization of its surface from Earth-based spectroscopy. A principal puzzle has been why Vesta exhibits relatively unweathered diagnostic optical features compared to other large asteroids. Is this due to the composition of this proto-planet or the space environment at Vesta? Alteration or weathering of materials in space normally develops as the products of several processes accumulate on the surface or in an evolving particulate regolith, transforming the bedrock into fragmental material with properties that may be measurably different from the original. Data from Dawn reveal that the regolith of Vesta is exceptionally diverse. Regional surface units are observed that have not been erased by weathering with time. Several morphologically-fresh craters have excavated bright, mafic-rich materials and exhibit bright ray systems. Some of the larger craters have surrounding subdued regions (often asymmetric) that are lower in albedo and relatively red-sloped in the visible while exhibiting weaker mafic signatures. Several other prominent craters have rim exposures containing very dark material and/or display a system of prominent dark rays. Most, but not all, dark areas associated with craters exhibit significantly lower spectral contrast, suggesting that either a Vesta lithology with an opaque component has been exposed locally or that the surface has been contaminated by a relatively dark impactor. Similarly, most, but not all, bright areas associated with craters exhibit enhanced mafic signatures compared to surroundings. On a regional scale, the large south polar structure and surrounding terrain exhibit relatively strong mafic absorption features, suggesting either a concentration of mafic materials or that materials exposed have been less affected by space weathering products. These combined initial observations indicate some space weathering processes are active in this part of the main asteroid belt, but are highly variable across the surface of Vesta. Such processes include: impacts from wandering asteroidal debris and local mixing at both micro- and macro-scales, irradiation by solar wind and galactic particles, production and distribution of impact breccias or melt products, and local movement of materials to gravity lows (gradual as well as sudden).

Pieters, C. M.; Blewett, D. T.; Gaffey, M.; Mittlefehldt, D. W.; De sanctis, M.; Reddy, V.; Coradini, A.; Nathues, A.; Denevi, B. W.; Li, J.; McCord, T. B.; Marchi, S.; Palmer, E. E.; Sunshine, J. M.; Filacchione, G.; Ammannito, E.; Raymond, C. A.; Russell, C. T.

2011-12-01

49

Evidence of Space Weathering Processes Across the Surface of Vesta  

NASA Technical Reports Server (NTRS)

As NASA s Dawn spacecraft explores the surface of Vesta, it has become abundantly clear that Vesta is like no other planetary body visited to date. Dawn is collecting global data at increasingly higher spatial resolution during its one-year orbital mission. The bulk properties of Vesta have previously been linked to the HED meteorites through remote mineral characterization of its surface from Earth-based spectroscopy. A principal puzzle has been why Vesta exhibits relatively unweathered diagnostic optical features compared to other large asteroids. Is this due to the composition of this proto-planet or the space environment at Vesta? Alteration or weathering of materials in space normally develops as the products of several processes accumulate on the surface or in an evolving particulate regolith, transforming the bedrock into fragmental material with properties that may be measurably different from the original. Data from Dawn reveal that the regolith of Vesta is exceptionally diverse. Regional surface units are observed that have not been erased by weathering with time. Several morphologically-fresh craters have excavated bright, mafic-rich materials and exhibit bright ray systems. Some of the larger craters have surrounding subdued regions (often asymmetric) that are lower in albedo and relatively red-sloped in the visible while exhibiting weaker mafic signatures. Several other prominent craters have rim exposures containing very dark material and/or display a system of prominent dark rays. Most, but not all, dark areas associated with craters exhibit significantly lower spectral contrast, suggesting that either a Vesta lithology with an opaque component has been exposed locally or that the surface has been contaminated by a relatively dark impactor. Similarly, most, but not all, bright areas associated with craters exhibit enhanced mafic signatures compared to surroundings. On a regional scale, the large south polar structure and surrounding terrain exhibit relatively strong mafic absorption features, suggesting either a concentration of mafic materials or that materials exposed have been less affected by space weathering products. These combined initial observations indicate some space weathering processes are active in this part of the main asteroid belt, but are highly variable across the surface of Vesta. Such processes include: impacts from wandering asteroidal debris and local mixing at both micro- and macro-scales, irradiation by solar wind and galactic particles, production and distribution of impact breccias or melt products, and local movement of materials to gravity lows (gradual as well as sudden).

Pieters, Carle M.; Blewett, David T.; Gaffey, Michael; Mittlefehldt, David W.; CristinaDeSanctis, Maria; Reddy, Vishnu; Coradini, Angioletta; Nathues, Andreas; Denevi, Brett W.; Li, Jian-Yang; McCord, Thomas B.; Marchi, Simone; Palmer, Eric E.; Sunshine, Jessica M.; Filacchione, Gianrico; Ammannito, Eleonora; Raymond, Carol A.; Russell, Christopher T.

2011-01-01

50

State of the Atmosphere: Interpreting Weather Observations  

NSDL National Science Digital Library

The purpose of this lesson is to let students analyze atmospheric radiosonde data from a balloon launched at NASA Langley Research Center by teachers attending a workshop. Other resources are included to assist in interpreting the observations. Students are asked to explain in paragraph format their interpretation of the atmospheric conditions depicted by the data and the graph produced using the data.

Lafrance, Kim

51

Surface microcracking induced by weathering of polycarbonate sheet  

Microsoft Academic Search

Polycarbonate sheet subjected to outdoor weathering for relatively short periods develops a network of surface microcracks on the side exposed to solar radiation. Artificial weathering and SEM microscopy were used to illustrate the process of microcrack formation. Microcracking occurs under the influence of light radiation in conjunction with cycling of either temperature and moisture or temperature alone. The use of

A. Blaga; R. S. Yamasaki

1976-01-01

52

Weather  

NSDL National Science Digital Library

This is a first grade weather unit. SEASONS Fall Winter Build a Snowman Spring Summer What things determine and effect the weather? Cloud Precipitation Sunshine Temperature Visibility Wind Direction Wind Force WEATHER VIDEOS Tornado Hurricane Hail Lightning FUN AND GAMES Dress the Bear for the Weather The Great Weather Race Game Weather coloring books for kids ...

Stearns, Ms.

2008-10-25

53

A New Perspective on Surface Weather Maps  

ERIC Educational Resources Information Center

A two-dimensional weather map is actually a physical representation of three-dimensional atmospheric conditions at a specific point in time. Abstract thinking is required to visualize this two-dimensional image in three-dimensional form. But once that visualization is accomplished, many of the meteorological concepts and processes conveyed by the…

Meyer, Steve

2006-01-01

54

Weather  

NSDL National Science Digital Library

Have you ever wondered how the weather man, or meteorolgist, on TV knows what to say about tomorrow\\'s weather? It\\'s because they have certain tools that they use that help them predict what the weather will be. Throughout this school year you are going to be making tools and predicting weather just like a meterorologist! Task You are going to be weather forcasters! You are going to record and track weather patterns throughout the year. You will also use weather tools to make predictions about the weather like real weather forecasters! The Process 1. First we need to learn a little bit about weather so ...

Williams, Ms.

2005-10-25

55

Weather Information for Surface Transportation. National Needs Assessment Report.  

National Technical Information Service (NTIS)

In 1998, a federal interagency committee identified the weather information needs of surface transportation sectors as a priority for coordinated action. In response, the Office of the Federal Coordinator for Meteorological Services and Supporting Researc...

2002-01-01

56

Use of meteorological satellite observations in weather modification programs  

NASA Technical Reports Server (NTRS)

The potential value of weather satellite data in field operations of weather modification is appraised. It was found that satellites could play a useful role in operational weather modification projects, particularly in the recognition of treatment opportunities. Satellite cloud photographs and infrared observations appear promising in the identification of treatment opportunities in seeding orographic cloud systems for increased snowpack, in seeding convective clouds for increased rainfall, in identifying hail threats, and in tracking and observing hurricanes as an aid to timing and location of seeding treatments. It was concluded that the potential value of satellite data in the treatment and evaluation phases of operational projects is not as great as in the recognition of treatment opportunity.

Dennis, A. S.; Smith, P. L., Jr.; Biswas, K. R.

1973-01-01

57

Generation of Multivariate Surface Weather Series with Use of the Stochastic Weather Generator Linked to Regional Climate Model  

NASA Astrophysics Data System (ADS)

The regional-scale simulations of weather-sensitive processes (e.g. hydrology, agriculture and forestry) for the present and/or future climate often require high resolution meteorological inputs in terms of the time series of selected surface weather characteristics (typically temperature, precipitation, solar radiation, humidity, wind) for a set of stations or on a regular grid. As even the latest Global and Regional Climate Models (GCMs and RCMs) do not provide realistic representation of statistical structure of the surface weather, the model outputs must be postprocessed (downscaled) to achieve the desired statistical structure of the weather data before being used as an input to the follow-up simulation models. One of the downscaling approaches, which is employed also here, is based on a weather generator (WG), which is calibrated using the observed weather series and then modified (in case of simulations for the future climate) according to the GCM- or RCM-based climate change scenarios. The present contribution uses the parametric daily weather generator M&Rfi to follow two aims: (1) Validation of the new simulations of the present climate (1961-1990) made by the ALADIN-Climate/CZ (v.2) Regional Climate Model at 25 km resolution. The WG parameters will be derived from the RCM-simulated surface weather series and compared to those derived from observational data in the Czech meteorological stations. The set of WG parameters will include selected statistics of the surface temperature and precipitation (characteristics of the mean, variability, interdiurnal variability and extremes). (2) Testing a potential of RCM output for calibration of the WG for the ungauged locations. The methodology being examined will consist in using the WG, whose parameters are interpolated from the surrounding stations and then corrected based on a RCM-simulated spatial variability. The quality of the weather series produced by the WG calibrated in this way will be assessed in terms of selected climatic characteristics focusing on extreme precipitation and temperature characteristics (including characteristics of dry/wet/hot/cold spells). Acknowledgements: The present experiment is made within the frame of projects ALARO (project P209/11/2405 sponsored by the Czech Science Foundation), WG4VALUE (project LD12029 sponsored by the Ministry of Education, Youth and Sports) and VALUE (COST ES 1102 action).

Dubrovsky, M.; Farda, A.; Huth, R.

2012-12-01

58

Titan's seasonal weather patterns, associated surface modification, and geological implications  

NASA Astrophysics Data System (ADS)

Model predictions [e.g., 1-3] and observations [e.g., 4,5] illustrate changes in Titan's weather patterns related to the seasons (Fig. 1). In two cases, surface changes were documented following large cloud outbursts (Figs. 2, 3): the first in Arrakis Planitia at high southern latitudes in Fall 2004, during Titan's late southern summer [6]; and the second at lows southern latitudes in Concordia and Hetpet Regiones, Yalaing Terra (Fig. 3), and Adiri, in Fall 2010, just over a year after Titan's northern vernal equinox [4, 7, 8]. Not only do these storms demonstrate Titan's atmospheric conditions and processes, they also have important implications for Titan's surface process, its methane cycle, and its geologic history.

Turtle, E. P.; Perry, J. E.; Barnes, J. W.; McEwen, A. S.; Barbara, J. M.; Del Genio, A. D.; Hayes, A. G.; West, R. A.; Lorenz, R. D.; Schaller, E. L.; Lunine, J. I.; Ray, T. L.; Lopes, R. M. C.; Stofan, E. R.

2013-09-01

59

Observed Weather Satellite Thermal IR Responses Prior to Earthquakes  

Microsoft Academic Search

A number of observers claim to have seen thermal anomalies prior to earthquakes, but subsequent analysis by others have failed to produce similar findings. It was the purpose of this study to determine if thermal anomalies could be found in association with known earthquakes by systematically co-registering weather satellite images at the sub-pixel level and then determining if statistically significant

N. A. Bryant; A. L. Zobrist; L. L. Logan; F. Freund; S. Nishenko

2002-01-01

60

Aviation Weather Observations for Supplementary Aviation Weather Reporting Stations (SAWRS) and Limited Aviation Weather Reporting Stations (LAWRS). Federal Meteorological Handbook No. 9.  

ERIC Educational Resources Information Center

This handbook provides instructions for observing, identifying, and recording aviation weather at Limited Aviation Weather Reporting Stations (LAWRS) and Supplementary Aviation Weather Reporting Stations (SAWRS). Official technical definitions, meteorological and administrative procedures are outlined. Although this publication is intended for use…

Department of Transportation, Washington, DC.

61

Weathering  

NSDL National Science Digital Library

This course handout covers the processes and effects of weathering. The purpose of this handout is to contrast weathering and erosion, contrast and discuss chemical and mechanical weathering, list the products resulting from the chemical weathering of igneous rocks, and list and discuss the factors that influence the type and rate of rock weathering. Many photographs accompany this summary which depict weathered landscapes. Links are provided to the online Physical Geology resources at Georgia Perimeter College.

Gore, Pamela

1995-08-29

62

SEPSAT – A Nanosatellite to Observe Parameters of Space Weather  

Microsoft Academic Search

\\u000a SEPSAT (Spherical EUV- and Plasma Spectrometer-Satellite) is a nanosatellite that will observe several parameters of space\\u000a weather, especially solar Extreme Ultraviolet Radiation (EUV), the higher atmosphere and effects of solar fluctuation on parameters\\u000a of the ionosphere. This helps to improve our knowledge of integrity and accuracy of GNSS signals, the origin and variation\\u000a of EUV radiation and finally the composition

Jens Rießelmann; Franziska Arlt; Klaus Brieß; Lars Dornburg; Kay Köhler; Jana Weise

63

Surface chemistry associated with the cooling and subaerial weathering of recent basalt flows  

USGS Publications Warehouse

The surface chemistry of fresh and weathered historical basalt flows was characterized using surface-sensitive X-ray photoelectron spectroscopy (XPS). Surfaces of unweathered 1987-1990 flows from the Kilauea Volcano, Hawaii, exhibited variable enrichment in Al, Mg, Ca, and F due to the formation of refractory fluoride compounds and pronounced depletion in Si and Fe from the volatilization of SiF4 and FeF3 during cooling. These reactions, as predicted from shifts in thermodynamic equilibrium with temperature, are induced by diffusion of HF from the flow interiors to the cooling surface. The lack of Si loss and solid fluoride formation for recent basalts from the Krafla Volcano, Iceland, suggest HF degassing at higher temperatures. Subsequent short-term subaerial weathering reactions are strongly influenced by the initial surface composition of the flow and therefore its cooling history. Successive samples collected from the 1987 Kilauea flow demonstrated that the fluoridated flow surfaces leached to a predominantly SiO2 composition by natural weathering within one year. These chemically depleted surfaces were also observed on Hawaiian basalt flows dating back to 1801 AD. Solubility and kinetic models, based on thermodynamic and kinetic data for crystalline AlF3, MgF2, and CaF2, support observed elemental depletion rates due to chemical weathering. Additional loss of alkalis from the Hawaiian basalt occurs from incongruent dissolution of the basalt glass substrate during weathering. ?? 1992.

White, A. F.; Hochella, Jr. , M. F.

1992-01-01

64

Limited Surface Observations Climatic Summary (LISOCS), Camp Zama/Kastner AAF, Japan.  

National Technical Information Service (NTIS)

This report presents a statistical data summary of surface weather observation climatology at Camp Zama/Kastner AAF Japan. The summary is in five parts: Weather conditions and atmospheric phenomena; Surface winds; Ceiling and visibility; Psychrometric sum...

1988-01-01

65

Mobile vehicle road and weather observation quality check methods  

NASA Astrophysics Data System (ADS)

Today State Departments of Transportation rely more and more on road weather data to make maintenance decisions. Inaccurate data can result in wrong treatment applications or inadequate staffing levels to maintain the roadway at the desired level of service. Previous methods of road condition data reporting have been limited to static in situ sensor stations. These road weather information systems (RWIS) provide varied data about precipitation, winds, temperature, and more, but their siting does not always provide an accurate representation of weather and road conditions along the roadway. The use of mobile data collection from vehicles travelling the highway corridors may assist in the locations where RWIS sitings are sparse or non-existent. The United States Department of Transporation's "Connected Vehicle" (formally IntelliDrive) research project is designed to create a fully connected transportation system providing road and weather data collection from an extensive array of vehicles. While the implementation of Connected Vehicle is in the future, some of the theories and technologies are already in place today. Several states, as a part of the Pooled Fund Study Maintenance Decision Support System (MDSS), have equipped their winter maintenance vehicles with Mobile Data Collection Automated / Vehicle Location (MDC/AVL) systems. In addition, since 1996, automobiles sold in the United States are required to be equipped with an Onboard Diagnostic Version 2 (OBDII) port that streams live data from sensors located in and around the vehicle. While these sensors were designed for vehicle diagnostics, some of the data can be used to determine weather characteristics around the vehicle. The OBDII data can be collected by a smartphone and sent to a server in real time to be processed. These mobile systems may fill the information gap along the roads that stationary environmental sensor stations are not able to collect. Particular concern and care needs to be focused on data quality and accuracy, requiring the development of quality checks for mobile data collection. Using OBDII-equipped automobiles and mobile collection methods, we can begin to address issues of data quality by understanding, characterizing, and demonstrating the quality of mobile system observations from operational and research environments. Several forms of quality checking can be used, including range checks, Barnes spatial checks, comparing vehicle data to road weather models, and applying Clarus quality check methodologies and algorithms to mobile observations. Development of these quality checks can lead to the future integration of mobile data into the Clarus system, data implementation for improved forecasting, maintenance decision support, and traveler safety. This paper will discuss the benefits and challenges in mobile data collection, along with how the development and implementation of a system of quality checks will improve the quality and accuracy of mobile data collection.

Koller, Daniel Raymond

66

Observational and modelling studies of Australian severe weather  

NASA Astrophysics Data System (ADS)

The forecastability of severe weather conditions over sub-tropical Australia are tested with a mesoscale model capable of running at high resolutions over a region of interest anywhere in the world. Improved forecast output, for example, of precipitation, wind speed/direction and humidity which are required to indicate severe weather conditions are dependent on model improvements and the following areas are addressed: (1)data; (2)theory; (3)model; and, (4)computing. The initial condition uncertainty inherent in the data which is used in the analysis to initialise numerical weather prediction (NWP) models is addressed through two ensemble forecasting studies, one on rainfall from a mesoscale system and the other on the central low position, wind and rainfall distribution of an explosive east coast low. Also, relating to data, some major mesoscale phenomena are described in the form of New South Wales coastal ridging which helps produce severe weather in this area and which needs to be captured by a mesoscale NWP model in order that improved predictions can be made. In terms of theory the major focus is on the ensemble methodology and on the use of improved precipitation parameterisations, namely, those of Fritsch-Chappell and Kain-Fritsch. The mesoscale model development is extended through the use of increased resolution studies, for example, by showing statistically significant greater than operational skill in predicting details of wind, relative humidity and temperature patterns both near the surface and above the boundary layer in relation to the Sydney January 1994 bushfire weather; by including an option for a Lagrangian particle dispersion model; and by replacement of a previously inadequate representation of cumulus convection which was required to represent the effects of mesoscale downdrafts which are essential for the successful prediction of the squall-line over Sydney in Chapter 7. Mesoscale weather prediction is one of the so called `grand challenges' of computational science in that it requires large amounts of memory and very efficient use of high performance computers. In this thesis the computations ranged form multiprocessor shared memory main frames; high performance work stations; and, now state-of-the-art Pentium PCs. Each of these machines has its distinct requirements for optimisation. Much work has been dedicated in producing code that transfers easily between platforms.

Speer, Milton Samuel

1998-09-01

67

Weather  

NSDL National Science Digital Library

The National Oceanic and Atmospheric Administration (NOAA) provides these two Websites on weather. The first site serves as a major hub for information related to weather, with links to primary data sources, forecasts, maps, images (such as the latest satellite imagery for North America), and a wealth of other data, including space weather. Researchers will also find links to national weather research centers and other related agencies.

68

Weather  

NSDL National Science Digital Library

What are the different types of weather? In this project you will compare different types of weather by drawing pictures and making it into a flip book. First you will begin by learning about the different types of weather. Read about each topic. Then get together with your partner and draw a picture of each type of weather. 1. Thunder storm Thunder storm Thunder storm Kids 2. Lightning Lightning Lightning picture 3. Tornado Tornadoes Tornado Kids 4. ...

Jennie, Miss

2009-10-22

69

Integrated Surface Hourly Observations, 1995-1999. Volumes 17-20.  

National Technical Information Service (NTIS)

This 4-disc collection contains worldwide surface weather observations from about 20,000 stations. The CD-ROM's also contain hourly and synoptic weather observations. The data is broken down by station, year, month, day, hour and minute.

2000-01-01

70

Integrated Surface Hourly Observations, 1995-1999. Volumes 9-12.  

National Technical Information Service (NTIS)

This 4-disc collection contains worldwide surface weather observations from about 20,000 stations. The CD-ROM's also contain hourly and synoptic weather observations. The data is broken down by station, year, month, day, hour and minute.

2000-01-01

71

Integrated Surface Hourly Observations, 1995-1999. Volumes 5-8.  

National Technical Information Service (NTIS)

This 4-disc collection contains worldwide surface weather observations from about 20,000 stations. The CD-ROM's also contain hourly and synoptic weather observations. The data is broken down by station, year, month, day, hour and minute.

2000-01-01

72

Integrated Surface Hourly Observations, 1995-1999. Volumes 13-16.  

National Technical Information Service (NTIS)

This 4-disc collection contains worldwide surface weather observations from about 20,000 stations. The CD-ROM's also contain hourly and synoptic weather observations. The data is broken down by station, year, month, day, hour and minute.

2000-01-01

73

Integrated Surface Hourly Observations, 1995-1999. Volumes 1-4.  

National Technical Information Service (NTIS)

This 4-disc collection contains worldwide surface weather observations from about 20,000 stations. The CD-ROM's also contain hourly and synoptic weather observations. The data is broken down by station, year, month, day, hour and minute.

2000-01-01

74

Observations and Modeling of Space Weather Impacts on the Earth  

NASA Astrophysics Data System (ADS)

``Space weather'' refers to conditions in the solar wind, magnetosphere, ionosphere, and upper atmosphere, that influence space-borne and ground-based technological systems and can endanger human space exploration. These effects are caused by variations in solar photon and particle radiation due to flares and coronal mass ejections, and changes in the solar/interplanetary magnetic field, that impact the magnetosphere and ionosphere. Space weather can initiate satellite failures, interfere with radio communications, cause navigation errors, disrupt electrical power distribution systems, and expose astronauts to dangerous levels of radiation. Mitigation requires both a better understanding of the space environment, and developing the ability to forecast conditions in space. The development of first-principles numerical models of the solar-terrestrial system gives us insight into the causes and nature of these phenomena, and holds the promise of ultimately being able to acquire a short-term predictive capability for some of them. This presentation will describe what we do and don't understand about the basic physics behind space weather, discuss some of its aspects and effects, and describe the latest observational and modeling efforts

Solomon, Stanley C.

2006-10-01

75

Land-surface influences on weather and climate  

NASA Technical Reports Server (NTRS)

Land-surface influences on weather and climate are reviewed. The interrelationship of vegetation, evapotranspiration, atmospheric circulation, and climate is discussed. Global precipitation, soil moisture, the seasonal water cycle, heat transfer, and atmospheric temperature are among the parameters considered in the context of a general biosphere model.

Baer, F.; Mintz, Y.

1984-01-01

76

Observations of upper atmospheric weather during solar minimum winter  

SciTech Connect

The authors report on a wide variety of thermospheric and ionospheric observations from three consecutive January World Day campaign periods. Despite remarkably similar geophysical conditions characterizing the in situ forcing of the upper atmosphere during these solar minimum campaigns, they find significant variability in the observations of the ionosphere and thermosphere particularly at low latitudes in the American sector. In addition, they present further observational evidence of the unexpected exospheric temperature suppression at low latitudes initially reported by Hagran and Salah (1988). They discuss the lower and upper atmospheric coupling mechanisms of plausible importance to the interpretation of the observed thermospheric weather patterns. They report evidence that lower thermospheric (NO) (nitric oxide number density) and upward propagating atmospheric tides affected the thermospheric energy and momentum budgets during the campaign periods.

Hagan, M.E. (Massachusetts Inst. of Tech., Westford (United States) National Center for Atmospheric Research, Boulder, CO (United States)); Barth, C.A. (Univ. of Colorado, Boulder (United States)); Tobiska, W.K. (Univ. of California, Berkeley (United States)); Manson, A.H. (Univ. of Saskatchewan, Saskatoon (Canada)); Vincent, R.A. (Univ. of Adelaide (Australia)); Buonsanto, M.J. (Massachusetts Inst. of Tech., Westford (United States)); Burnside, R.G. (Cornell Univ., Arecibo (Puerto Rico)); Wickwar, V.B. (Utah State Univ., Logan (United States))

1992-04-01

77

Surface Transportation Weather Decision Support Requirements. Draft Version 2.0. Operational Concept Description. Advanced-Integrated Decision Support Using Weather Information for Surface Transportation Decisions Makers.  

National Technical Information Service (NTIS)

This is a draft document for the Surface Transportation Weather Decision Support Requirements (STWDSR) project. The STWDSR project is being conducted for the FHWAs Office of Transportation Operations (HOTO) Road Weather Management Program by Mitretek Syst...

P. Pisano G. G. Nelson

2000-01-01

78

Does mineral surface area affect chemical weathering rates?  

NASA Astrophysics Data System (ADS)

Iceland is a basaltic volcanic island representative of the high relief, volcanic and tectonic active islands that contribute over 45% of river suspended material to the oceans worldwide (Milliman and Syvitski, 1992). These islands have enormous mechanical and chemical weathering rates due to the combined effects of high relief, high runoff, the presence of glaciers and easily weathered volcanic rocks, and a lack of sedimentary traps. In total, Iceland delivers 0.7% of the worldwide river suspended matter flux to the ocean, which is approximately one fourth that of Africa (Tómasson, 1990). River suspended matter from volcanic islands is highly reactive in seawater and might play an important role in the global carbon cycle (Gislason et al., 2006). Thus it is important to define and understand the mechanical and chemical weathering rates of these islands. Experimental dissolution experiments performed in the laboratory suggest that chemical weathering rates should be proportional to rock-water interfacial surface area. This hypothesis is tested in the present study through a study of the chemical composition of suspended material collected from rivers located in Northeast Iceland. These rivers were selected for this study because their catchments essentially monolithic, consisting of uniform compositioned and aged basalts. Gaillardet (1999) described weathering intensities of the worlds river systems to be from 1 (low weathering intensity) to 25 (high weathering intensity). These indexes were calculated to be from 1.8 to 3.2 in rivers in NE-Iceland (Eiriksdottir et al., 2008). The surface area of sediments is inversely proportional to particle size; smaller particles have larger specific surface areas. As a result, smaller particles should weather faster. This trend is confirmed by the measured compositions of analyzed suspended material. The concentration of insoluble elements (Zr, Fe, Cu, Ni, Y) is found to increase in the suspended material, whereas the concentration of soluble elements (Na, Ca, Ba, V) decrease with decreasing particle size in samples collected from various catchments. References. Eiriksdottir E.S., Louvat P., Gislason S.R., Óskarsson N., Hardardóttir J., 2008. Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion. EPSL 272, 78-88 Gaillardet, J., Dupré, B., Allegre, C.J., Négrel, P., 1999b. Geochemistry of large river suspended sediments: silicate weathering or recycling tracer? Geochim. Cosmochim. Acta 63, 4037-4051. Gislason, S.R., Oelkers, E.H., Snorrason, Á., 2006. Role of river-suspended material in the global carbon cycle. Geology 34, 49-52. Milliman, J.D., Syvitski, J.P.M., 1992. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers. J. Geol. 100, 525-544. Tómasson, H., 1990. Suspended material in Icelandic rivers. In: Guttormur, S. (Ed.), Vatnid og Landid. Orkustofnun, Reykjavik, pp. 169-174.

Salome Eiriksdottir, Eydis; Reynir Gislason, Sigurdur; Oelkers, Eric H.

2010-05-01

79

Surface Landing Site Weather Analysis for NASA's Constellation Program  

NASA Technical Reports Server (NTRS)

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing of the Ares vehicles to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is art important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface weather conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center (MSFC) Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. This paper wiI1 describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that cab be obtained.

Altino, Karen M.; Burns, K. L.

2008-01-01

80

Potential Impacts of Stratospheric Observations on Weather Forecasts  

NASA Astrophysics Data System (ADS)

This study examines the potential impact of novel stratospheric measurements on tropospheric weather forecasts. We focus on the upper stratosphere, where routine measurements of temperature and winds are sparse, and where there is potential to expand the current observing system using measurements from the ARISE (Atmospheric Dynamics Research Infrastructure in Europe) network. We consider 30 day forecasts initiated just before Sudden Stratospheric Warmings (SSWs). Previous studies have shown a small but significant impact on tropospheric forecast skill, for NWP forecasts after 5 days, when stratospheric initial conditions are severely degraded, and a similar increase in forecast skill when the stratospheric state is damped towards observed conditions. Using a version of the second technique we are able to reproduce previous results, which show around a 5% increase in tropospheric forecast skill when the stratosphere is damped towards its observed state. We then use the same technique to compare the quantitative impact of damping the stratospheric state towards observations in the lower and upper stratosphere (with a boundary at 40km), and for observations in the European sector only.

Lee, Christopher; Charlton-Perez, Andrew; Harrison, R. Giles

2014-05-01

81

Weather.  

ERIC Educational Resources Information Center

This subject guide to weather resources includes Web sites, CD-ROMs and software, videos, books, audios, magazines, and professional resources. Related disciplines are indicated, age levels are specified, and a student activity is included. (LRW)

Web Feet K-8, 2000

2000-01-01

82

Weathering  

Microsoft Academic Search

In the natural environment, weathering and breakdown of stone is an accepted part of long-term landscape development but the\\u000a same acceptance of change and deterioration is not extended to stone used in construction especially when such deterioration\\u000a affects historically and\\/or culturally important structures. The value of an integrative approach to improve understanding\\u000a of weathering and failure of building stone is

P. A. Warke; J. McKinley; B. J. Smith

83

Effect of accelerated weathering on surface chemistry of modified wood  

NASA Astrophysics Data System (ADS)

In this study, the effects of UV-light irradiation and water spray on colour and surface chemistry of scots pine sapwood samples were investigated. The specimens were treated with chromated copper arsenate (CCA), a metal-free propiconazol-based formulation, chitosan, furfuryl alcohol and linseed and tall oils. The weathering experiment was performed by cycles of 2 h UV-light irradiation followed by water spray for 18 min. The changes at the surface of the weathered samples were characterised by Fourier transform infrared spectroscopy (FT-IR); colour characterizations were performed by measuring CIELab parameters. The results show that all treatment methods except chitosan treatment provided lower colour changes than the control groups after 800 h exposure in weathering test cycle, but differences between chitosan and control were also small. The lowest colour changes were found on linseed oil (full cell process) and CCA treated wood. FT-IR results show that oil treatment (linseed and tall oil) decreased the intensities of a lignin specific peak (1500-1515 cm -1). Absorption band changes at 1630-1660 cm -1 were reduced by all treatments.

Temiz, Ali; Terziev, Nasko; Eikenes, Morten; Hafren, Jonas

2007-04-01

84

The influence of aspect on the biological weathering of granites: observations from the Kunlun Mountains, China  

Microsoft Academic Search

Bedrock and boulder weathering in the higher elevation, permafrost areas of the Qinghai–Tibetan Plateau have usually been ascribed to frost action. For short periods during two summers, an attempt was made to better elucidate weathering processes in this region. A combination of visual observation coupled with rudimentary data regarding removable weathered material from the four cardinal aspects of granite boulders

Kevin Hall; Joselito M. Arocena; Jan Boelhouwers; Zhu Liping

2005-01-01

85

Aviation & Space Weather Policy Research: Integrating Space Weather Observations & Forecasts into Operations  

NASA Astrophysics Data System (ADS)

The American Meteorological Society and SolarMetrics Limited are conducting a policy research project leading to recommendations that will increase the safety, reliability, and efficiency of the nation's airline operations through more effective use of space weather forecasts and information. This study, which is funded by a 3-year National Science Foundation grant, also has the support of the Federal Aviation Administration and the Joint Planning and Development Office (JPDO) who is planning the Next Generation Air Transportation System. A major component involves interviewing and bringing together key people in the aviation industry who deal with space weather information. This research also examines public and industrial strategies and plans to respond to space weather information. The focus is to examine policy issues in implementing effective application of space weather services to the management of the nation's aviation system. The results from this project will provide government and industry leaders with additional tools and information to make effective decisions with respect to investments in space weather research and services. While space weather can impact the entire aviation industry, and this project will address national and international issues, the primary focus will be on developing a U.S. perspective for the airlines.

Fisher, G.; Jones, B.

2006-12-01

86

Multipurpose Weather Roundup Program.  

National Technical Information Service (NTIS)

Program RWR9 reads Surface Airways Observations (SAO's) from the local AFOS database and reformats them into plain language collectives for Hourly, State, and Regional Weather Roundups. Output is suitable for direct transmission on the state weather wire....

W. E. Sunkel

1983-01-01

87

Meteorological observation with Doppler and Raman lidars and comparison with numerical weather simulations  

NASA Astrophysics Data System (ADS)

Meteorological observation data such as temperature, humidity, wind speed and wind direction are important for validating and improving numerical weather simulation models. Lidar is an effective method for acquiring such data with high range resolution and short time intervals. In this study, we carried out a field observation with coherent Doppler Lidar and Raman Lidar systems at the coastal area of Yokosuka, Japan, and compared the observed data with the results of numerical weather simulations. We obtained the vertical profiles of horizontal wind speeds and wind directions by Doppler Lidar with 65 m vertical range resolution, and the vertical profiles of the water vapor mixing ratio by Raman Lidar with 20 m vertical range resolution at the lower atmospheric boundary layer (200-600 m height from ground level). These data were acquired at time intervals of 10 minutes. We found an interesting phenomenon from observed data indicating that, under weak wind conditions, water vapor in the atmosphere significantly increased just after a definite change in wind direction from land breeze to sea breeze. A similar phenomenon was also predicted by the numerical weather simulation with the same meteorological and terrestrial conditions. We analyzed the numerical results and found that the change in water vapor mentioned above is mainly caused by the difference between the evaporation from land and sea surfaces, which were located upwind of the land and sea breezes, respectively.

Tamura, Hidetoshi; Kihara, Naoto; Fujii, Takashi; Fukuchi, Tetsuo; Wada, Koji; Hirakuchi, Hiromaru

2012-11-01

88

Bacillus qingshengii sp. nov., a rock-weathering bacterium isolated from weathered rock surface.  

PubMed

A novel type of rock-weathering bacterium was isolated from weathered rock (tuff) surface collected from Dongxiang (Jiangxi, eastern China). Cells of strain G19(T) were Gram-reaction-positive, rod-shaped, endospore-forming and non-motile. The strain was aerobic, catalase- and oxidase-positive, and grew optimally at 30 °C and pH 7.0. On the basis of 16S rRNA gene sequence analysis, strain G19(T) was shown to belong to the genus Bacillus and the closest phylogenetic relatives were Bacillus aryabhattai B8W22(T) (97.4?%) and Bacillus megaterium IAM 13418(T) (97.1?%). The DNA G+C content was 36.7 mol% and the predominant respiratory quinone was MK-7. The major fatty acids were iso-C14?:?0, iso-C15?:?0 and anteiso-C15?:?0. The polar lipid profile of strain G19(T) contained phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and an unidentified lipid. Based on the low level of DNA-DNA relatedness (ranging from 49.4?% to 55.0?%) to these type strains of species of the genus Bacillus and unique phenotypic characteristics, strain G19(T) represents a novel species of the genus Bacillus, for which the name Bacillus qingshengii sp. nov. is proposed. The type strain is G19(T) (?=?CCTCC AB 2013273(T)?=?JCM 19454(T)). PMID:24801156

Xi, Jun; He, Lin-Yan; Huang, Zhi; Sheng, Xia-Fang

2014-07-01

89

Coleman AAF, Germany (West). Limited Surface Observations Climatic Summary (LISOCS).  

National Technical Information Service (NTIS)

This report is similar to a Revised Uniform Summary of Surface Weather Observations (RUSSWO) except the summary generated is from data observed at limited-duty observation sites. This summary is blocked based on the normal hours of observation and only th...

1983-01-01

90

Surface Meteorological Observation System (SMOS) Handbook  

SciTech Connect

The Surface Meteorological Observation System (SMOS) mostly uses conventional in situ sensors to obtain 1-minute, 30-minute, and 1440-minute (daily) averages of surface wind speed, wind direction, air temperature, relative humidity (RH), barometric pressure, and precipitation at the Central Facility and many of the extended facilities of the Southern Great Plains (SGP) climate research site. The SMOSs are not calibrated as systems. The sensors and the data logger (which includes the analog-to-digital converter, or A/D) are calibrated separately. All systems are installed using components that have a current calibration. SMOSs have not been installed at extended facilities located within about 10 km of existing surface meteorological stations, such as those of the Oklahoma Mesonet. The Surface Meteorological Observation Systems are used to create climatology for each particular location, and to verify the output of numerical weather forecast and other model output. They are also used to “ground-truth” other remote sensing equipment.

Ritsche, MT

2008-03-01

91

Weather Radars and Lidar for Observing the Atmosphere  

NASA Astrophysics Data System (ADS)

The Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado develops and deploys state-of-the-art ground-based radar, airborne radar and lidar instruments to advance scientific understanding of the earth system. The ground-based radar (S-Pol) is equipped with dual-wavelength capability (S-band and Ka-band). S-Pol is the only transportable radar in the world. In order to capture faster moving weather events such as tornadoes and record observations of clouds over rugged mountainous terrain and ocean, an airborne radar (ELDORA) is used. It is the only airborne Doppler meteorological radar that is able to detect motions in the clear air. The EOL is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add complementary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. The envisioned capability of a millimeter wave radar system on GV is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction. The presentation will describe the capabilities of current instruments and also planned instrumentation development.

(Vivek) Vivekanandan, J.

2010-05-01

92

TOF-SIMS investigations on weathered silver surfaces.  

PubMed

Silver-coated quartz crystal microbalance (QCM) disks were treated under different environmental conditions (including changes in parameters such as relative humidity (%RH) and SO(2)/H(2)S content) in atmospheres of synthetic air and pure N(2) for 24 h in a weathering chamber. The corroded surfaces were subjected to depth profiling by a time of flight (TOF) secondary ion mass spectrometry (SIMS) instrument, equipped with a Bi(+) analysis gun and Cs(+) sputter gun. The evaluation of the in-depth distribution of several elements and species provides evidence for the formation of a corrosion layer containing Ag(2)SO(3), even in the absence of oxidizing agents, such as H(2)O(2) or NO(2). Furthermore it could be elucidated that the thickness of the formed Ag(2)SO(3) layer does not depend on the SO(2) concentration but rather on the humidity and oxygen content of the ambient atmosphere. In weathering experiments in atmospheres composed of synthetic air, humidity, and H(2)S, the presence of different oxygen species (surface and bulk) and silver sulfide could be detected by TOF-SIMS depth profiling experiments. The obtained results for both acidifying gases are in good correlation with the corresponding tapping mode atomic force microscopy (TM-AFM) investigations and in situ QCM measurements. PMID:18004549

Schnöller, J; Wiesinger, R; Kleber, C; Hilfrich, U; Schreiner, M; Hutter, H

2008-03-01

93

Weather  

NSDL National Science Digital Library

In the project you will learn about thunderstorms and tornadoes and play a weather matching game. What exactly are thunderstorms and tornadoes? Use your T- chart to explain some facts about a thunderstorm and a tornado as we review each. T-Chart Begin by reviewing what a thunderstorm is and how they form. Thunderstorm information What is a thunderstorm? What are thunderstorms most likely to occur? What causes thunder? Next review what a tornado ...

Caitlin, Ms.

2009-10-21

94

Tropical Ocean Surface Energy Balance Variability: Linking Weather to Climate Scales  

NASA Technical Reports Server (NTRS)

Radiative and turbulent surface exchanges of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth s energy and water balance. Characterizing the spatiotemporal variability of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. These fluxes are integral components to tropical ocean-atmosphere variability; they can drive ocean mixed layer variations and modify the atmospheric boundary layer properties including moist static stability, thereby influencing larger-scale tropical dynamics. Non-parametric cluster-based classification of atmospheric and ocean surface properties has shown an ability to identify coherent weather regimes, each typically associated with similar properties and processes. Using satellite-based observational radiative and turbulent energy flux products, this study investigates the relationship between these weather states and surface energy processes within the context of tropical climate variability. Investigations of surface energy variations accompanying intraseasonal and interannual tropical variability often use composite-based analyses of the mean quantities of interest. Here, a similar compositing technique is employed, but the focus is on the distribution of the heat and moisture fluxes within their weather regimes. Are the observed changes in surface energy components dominated by changes in the frequency of the weather regimes or through changes in the associated fluxes within those regimes? It is this question that the presented work intends to address. The distribution of the surface heat and moisture fluxes is evaluated for both normal and non-normal states. By examining both phases of the climatic oscillations, the symmetry of energy and water cycle responses are considered.

Roberts, J. Brent; Clayson, Carol Anne

2013-01-01

95

Weather Observer, 15-1. Military Curriculum Materials for Vocational and Technical Education.  

ERIC Educational Resources Information Center

This course, adapted from military curriculum materials for use in vocational and technical education, was designed to upgrade an apprentice weather observer to the weather observer specialist level. Intended to be used in a laboratory or on-the-job learning situation, it contains both basic information needed for review and supervisory…

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

96

Experimental observations of the effects of bacteria on aluminosilicate weathering  

Microsoft Academic Search

Mineral dissolution experiments using batch cultures of soil and groundwater bacteria were monitored with solution chemistry and various microscopic techniques to determine the effects of these organisms on weathering reactions. Several strains of bacteria produced organic and inorganic acids and extracellular polymers in culture, increasing the release of cations from biotite (Si, Fe, Al) and plagioclase feldspar (Si, Al) by

W. W. Barker; S. A. Welch; S. Chu; J. F. Banfield

1998-01-01

97

Synoptic observations of space weather processes in the inner magnetosphere  

Microsoft Academic Search

Space weather in the magnetosphere is driven by coronal mass ejections and other solar wind disturbances. The magnetosphere has, in turn, a remarkable capability of further processing the energy and plasma coming from the solar wind. One way of determining the severeness of magnetic storms is to estimate the strength of the westward ring current carried by ions at energies

H. Koskinen

2002-01-01

98

Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations  

NASA Technical Reports Server (NTRS)

Today s presentation describes how real time space weather data is used by the International Space Station (ISS) space environments team to obtain data on auroral charging of the ISS vehicle and support ISS crew efforts to obtain auroral images from orbit. Topics covered include: Floating Potential Measurement Unit (FPMU), . Auroral charging of ISS, . Real ]time space weather monitoring resources, . Examples of ISS auroral charging captured from space weather events, . ISS crew observations of aurora.

Minow, Joseph; Pettit, Donald R.; Hartman, William A.

2012-01-01

99

Geomorphic controls on mineral weathering, elemental transport, and production of mineral surface area in a schist bedrock weathering profile, Piedmont Pennsylvania  

NASA Astrophysics Data System (ADS)

We assess a deep chemical weathering profile in the context of geomorphic evolution in the Laurels Schist, a late proterozoic greenschist formation in the Christina River Basin Critical Zone Observatory located in the Piedmont region in southeastern Pennsylvania. Two 21-meter deep rotosonic drill cores were sampled at the ridge top and footslope positions in a first-order, forested watershed. The top meter was sampled at high-resolution in a soil pit adjacent to each drill core and along a hillslope transect to assess geomorphic controls on the weathering profile. Weathering processes in soil and saprolite were examined by observing changes in mineralogy, including the emergence of secondary phyllosilicate and oxide minerals; measuring specific surface area of bulk soil and saprolite; and by quantifying elemental mass changes of major and minor rock-forming elements. Mineral profiles were assessed using clay and bulk XRD, and reveal that kaolinite, a common secondary phyllosilicate, is present above 1.5 meters in the weathering profile. Specific surface area (SSA) values decrease with increasing depth to a critical depth around 2 meters, where the values of untreated (carbon-loaded) and muffled (carbon removed by heating) mineral grains converge to baseline SSA values below 10 m2g-1, indicating that carbon is sorbed with mineral surface area in the upper 2 meters. Immobile element concentrations decrease with increasing depth up to 3 meters, indicating that the preferential removal of mobile elements extends beyond the depth of C-mineral adsorption. Variability of immobile elements in the deep weathering profile reveal variations that could be the result of weathering in fractures but are more likely inherited by the rock composition and particle size of pre-metamorphosed parent rock.

Wenell, B.; Yoo, K.; Aufdenkampe, A. K.; Mahoney, J. B.; Lepak, L.

2013-12-01

100

Formation of the Surface Space Charge Layer in Fair Weather  

NASA Astrophysics Data System (ADS)

It is widely known that the positive space charge, caused by electrode effect action, is obtained near surface in fair weather. Space charge density depends on the different local features: meteorological conditions, aerosol particles concentration, convective transfer of the surface layer. Namely space charge determines the local variations of electric field. Space charge could be negative in condition of strong ionization rate in thin air layer near surface. The electrodynamic model, consisting of transfer equations of light ions and nucleuses, generated by interactions between lights ions and aerosol particles, and Poisson equation. The turbulent transfer members, electric field near the surface, the mobility of positive and negative ions, recombination coefficient, ionization rate, the number of elementary charges on the nuclei were took into account in the model equations. The time-space variations of positive and negative small and heavy ions, electric field, electrical conductivity, current density and space charge, depending on aerosol particles concentrations, turbulence and convective transfer ionization rate, aerosol particles size and number of charged on the particles are calculated. The mechanisms of turbulent and convection-turbulent surface layer electrodynamic structure forming in dependence of single and multi-charged aerosol particles for different physical and meteorological conditions are investigated. Increasing of turbulent mixing intensity leads to increasing of character electrode layer thickness, decreasing of space charge density value, decreasing of electric current conductivity value. The electrode effect of the whole layer remains constant. Increasing of aerosol particles concentration leads to decreasing of electrode effect within the whole electrode layer and increasing of electric field values, decreasing of space charge density values and current conductivity density. It was received that increasing of the aerosol particles concentration under weak turbulent mixing leads to increasing of the negative space charge density and its displacement to the surface level. Under severe contamination condition the electrodynamic structure of surface layer is primarily determined by negative space charge, generated by nucleuses. It was received that in case of small aerosol particles the surface layer electrodynamic structure is basically established by single- and double-charged particles. Single-charged and double-charged as triply-charged, fourfold-charged and fivefold-charged aerosol particles primarily affect on electrodynamic structure of the surface layer in case of increasing of aerosol particles size. The local variations of the electric field in different conditions were studied. Theoretical results are in a good agreement with experimental facts.

Redin, Alexander; Kupovykh, Gennady; Boldyreff, Anton

2014-05-01

101

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science  

NASA Technical Reports Server (NTRS)

We often look "through a glass, darkly" at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers are radiation crusts on cometary nuclei and iogenic components of sulfate hydrate deposits on the trailing hemisphere of Europa. Weathering processes include plasma ion implantation into surfaces, sputtering by charged particles and solar ultraviolet photons, photolytic chemistry driven by UV irradiation, and radiolytic chemistry evolving from products of charged particle irradiation. Regolith structure from impacts, and underlying deeper structures from internal evolution, affects efficacy of certain surface interactions, e.g. sputtering as affected by porosity and surface irradiation dosage as partly attenuated by local topographic shielding. These processes should be regarded for mission science planning as potentially enabling, e.g. since direct surface sputtering, and resultant surface-bound exospheres, can provide in-situ samples of surface composition to ion and neutral mass spectrometers on orbital spacecraft. Sample return for highest sensitivity compOSitional and structural analyses at Earth will usually be precluded by limited range of surface sampling, long times for return, and high cost. Targeted advancements in instrument technology would be more cost efficient for local remote and in-situ sample analysis. More realistic laboratory simulations, e.g. for bulk samples, are needed to interpret mission science observations of weathered surfaces. Space environment effects on mission spacecraft and science operations must also be specified and mitigated from the hourly to monthly changes in space weather and from longer term (e.g., solar cycle) evolution of space climate. Capable instrumentation on planetary missions can and should be planned to contribute to knowledge of interplanetary space environments. Evolving data system technologies such as virtual observatories should be explored for more interdisciplinary application to the science of planetary surface, atmospheric, magnetospheric, and interplanetary interactions.

Cooper, John F.

2011-01-01

102

Validation of the Space Weather Modeling Framework using observations from CHAMP and DMSP  

Microsoft Academic Search

The Space Weather Modeling Framework (SWMF) is a flexible framework for space weather simulation, which can couple magnetosphere and ionosphere processes. This work compares ionospheric outputs from SWMF with magnetic and plasma observations from CHAMP and DMSP satellites under both quiet and storm conditions, emphasizing the dependence of the model's performance for various magnetic local times, solar wind conditions, and

H. Wang; A. J. Ridley; H. Lühr

2008-01-01

103

Coastal observations of weather features in Senegal during the African Monsoon Multidisciplinary Analysis Special Observing Period 3  

NASA Astrophysics Data System (ADS)

During 15 August through 30 September 2006 (Special Observing Period 3, SOP3), key weather measurements are obtained from ground and aircraft platforms during the African Monsoon Multidisciplinary Analysis campaign. Key measurements are aimed at investigating African easterly waves (AEWs) and mesoscale convective systems in a coastal environment as they transition to the eastern Atlantic Ocean. Ground and aircraft instruments include polarimetric radar, a coarse and a high-density rain gauge network, surface chemical measurements, 12 m meteorological measurement, broadband IR, solar and microwave measurements, rawinsonde, aircraft dropsonde, lidar, and cloud radar measurements. Ground observations during SOP3 show that Senegal was influenced by 5 squall lines, 6 Saharan air layer intrusions, and 10 AEWs. Downstream tropical cyclones developed were associated with the passage of four AEWs. FA-20 aircraft measurements of microphysical aspects of 22 September squall line and several nondeveloping AEWs over the extreme eastern Atlantic Ocean are presented.

Jenkins, G.; Kucera, P.; Joseph, E.; Fuentes, J.; Gaye, A.; Gerlach, J.; Roux, F.; Viltard, N.; Papazzoni, M.; Protat, A.; Bouniol, D.; Reynolds, A.; Arnault, J.; Badiane, D.; Kebe, F.; Camara, M.; Sall, S.; Ndiaye, S. A.; Deme, A.

2010-09-01

104

Training Guide in Surface SAWRS Observations.  

ERIC Educational Resources Information Center

As a replacement of the 1949 primary training manual for supplementary aeronautical weather reports, instructions are presented in this Training Paper No. 5 for the purpose of guiding learners through their study of the Weather Service Observing Handbook (WSOH) No. 4. The content is divided into six chapters concerned with such topics as…

National Oceanic and Atmospheric Administration (DOC), Rockville, MD. National Weather Service.

105

Titan's rotation - Surface feature observed  

NASA Astrophysics Data System (ADS)

A surface feature or a near-surface fracture is suggested to account for the time variations in the 0.94, 1.08, and 1.28 micron atmospheric windows of Titan's geometric albedo, relative to its albedo in adjacent methane bands. These observations are noted to be consistent with synchronous rotation. They can also be explained by a 0.1-higher surface albedo on Titan's leading hemisphere.

Lemmon, M. T.; Karkoschka, E.; Tomasko, M.

1993-06-01

106

Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroid Space Weathering Studies  

NASA Technical Reports Server (NTRS)

Understanding the composition of Mercury's crust is key to comprehending the formation of the planet. The regolith, derived from the crustal bedrock, has been altered via a set of space weathering processes. These processes are the same set of mechanisms that work to form Mercury's exosphere, and are moderated by the local space environment and the presence of an intrinsic planetary magnetic field. The alterations need to be understood in order to determine the initial crustal compositions. The complex interrelationships between Mercury's exospheric processes, the space environment, and surface composition are examined and reviewed. The processes are examined in the context of our understanding of these same processes on the lunar and asteroid regoliths. Keywords: Mercury (planet) Space weathering Surface processes Exosphere Surface composition Space environment 3

Dominque, Deborah L.; Chapman, Clark R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Orlando, Thomas M.; Schriver, David; Sprague, Ann L.; Blewett, David T.; Gillis-Davis, Jeffrey J.; Feldman, William C.; Lawrence, David J.; Ho, George C.; Vilas, Faith; Pieters, Carle M.; McClintock, William E.; Helbert, Jorn

2011-01-01

107

Federal Cooperation toward a Nationwide Network of Weather and Climate Observing Networks  

NASA Astrophysics Data System (ADS)

Weather observing in the US has expanded well beyond its original scope, when it was largely the province of the Federal government. Much of today's observational data is collected by individuals or organizations outside the Federal domain. Application of all weather observations from across the enterprise would be useful in a variety of weather-related disciplines. However, many of those observations are not available or are not used because their quality is suspect or unknown to potential users. A broadly accepted and adopted system of standards to facilitate discovery, access, and selection of acceptable weather observations is needed to fully exploit the wealth of data being collected. Because of its still substantial role in taking and collecting weather observations, it is assumed that a system of standards employed by the Federal government would provide a strong basis for an enterprise-wide system. However, such a system, based on Federal requirements with due consideration of broader needs, does not exist. The effort to establish standards is a first step in a more comprehensive process of recognizing needs for mesoscale observations for a variety of applications, making all current observations-regardless of source-available to meet those needs, and planning for deployment of additional observing capability to fill the gaps. In response to the National Academy of Sciences report Observing Weather and Climate from the Ground Up-a Nationwide Network of Networks, the Office of the Federal Coordinator for Meteorology is working in conjunction with the American Meteorological Society and the National Earth Observation Task Force to address the challenges of building a weather observing and data management capability that meets the needs of a growing community of interest.

Stailey, J. E.

2011-12-01

108

Modelling Glacier Surface Temperature Using Weather Station Data and Synoptic Weather Conditions  

NASA Astrophysics Data System (ADS)

Glacier temperature can be directly measured at selected locations, but extrapolation is often required as data at high elevations are sparse and glacier-wide temperatures are needed for distributed melt models. A new model to extrapolate summer temperatures (May - August) is developed from data collected at Haig Glacier to address this need. Air temperatures are computed using the new model at Haig and Kwadacha Glaciers. The model accounts for solar radiation, albedo, synoptic weather systems, valley walls and elevation. It is driven by readily available weather station and synoptic data. While developing the model, an albedo model is created, the most effective way to include solar radiation is determined and the heating effects of valley walls are analyzed. The new model does not improve upon the constant lapse rate model. However, results suggest that month-specific multivariate models that have a greater emphasis on elevation may improve model performance.

Schaffer, Nicole

109

Weather Specialist/Aerographer's Mate.  

ERIC Educational Resources Information Center

This course trains Air Force personnel to perform duties prescribed for weather specialists and aerographer's mates. Training includes meteorology, surface and ship observation, weather radar, operation of standard weather instruments and communications equipment, and decoding and plotting of surface and upper air codes upon standard maps and…

Chanute AFB Technical Training Center, IL.

110

Characterizing the process and quantifying the rate of subaerial rock weathering on desert surfaces using roughness analysis  

NASA Astrophysics Data System (ADS)

Subaerial weathering of rocks is a common process observed on desert surfaces on Earth and other planetary terrestrial surfaces such as on Mars. On Earth, this weathering process has been previously identified as one of the key erosion agent driving geomorphic surface evolution and the development of desert pavements. And yet, fundamental aspects of the process, such as the relative contribution of the different weathering modes that drive it (e.g., mechanical breakdown of rocks, chemical weathering, aeolian abrasion and exfoliation) as well as the rate by which this weathering process occurs have not been systematically examined. Here, we present a new approach for quantitatively addressing these fundamental aspects of process geomorphology on desert surfaces. We focus here on co-genetic desert alluvial surfaces of different ages, i.e. alluvial chronosequences, which provide excellent recorders for the evolution of boulder-strewn surfaces into smooth desert pavements through in-situ subaerial weathering of rocks. Our approach combines independent measures of two different surface attributes: High resolution (mm-scale) 3D ground-based laser scanning (LiDAR) of surface micro-topography, and numerical dating of surface age. Roughness analysis of the LiDAR data in power spectral density (PSD) space allows us to characterize the geometric manifestation of rock weathering on the surface and to distinguish between the different weathering modes. Numerical age constraints provide independent estimates for the time elapsed since the process began. Accordingly, we are able to constrain surface roughness evolution on alluvial fan desert chronosequences through time, and present PSD analysis of surface roughness as a new quantitative tool to examine the process of subaerial rock weathering in desert environments. In this study we present results from two late Quaternary alluvial chronosequences along the Dead Sea Transform in the hyper-arid Negev desert of southern Israel. LiDAR scanning was applied on representative areas (~30-50 m2) of 10 separate surfaces ranging from rough Holocene surfaces to fairly smooth surfaces with well-developed pavements displaying an OSL age of 87 kyr. We find typical and recurring time-dependent changes in the offset as well as shape of the PSD curves in both chronosequences: PSD offset is continuously reduced over time reflecting the overall reduction in the amplitude of roughness at all wavelengths. The PSD curves display progressive moderation of slopes at the longer wavelengths with the moderation point itself systematically shifted to shorter wavelengths. This characteristic evolution of PSD offset and slope moderation at longer wavelengths reflects the typical break up of boulder-sized clasts through time as the surfaces mature into well-developed desert pavements and points towards mechanical breakdown as the dominant weathering mode. In addition, we are able to determine the rate by which the larger clasts are removed from the system. We build on these new insights into process and rate of rock weathering to propose PSD analysis of surface roughness as a complementary method for constraining the age of desert alluvial surfaces in places where 'conventional' dating cannot be applied.

Mushkin, Amit; Sagy, Amir; Trabelci, Eran

2013-04-01

111

Changes in the weathering of rock surfaces in different geomorphological environments: glacial, nival and coastal  

Microsoft Academic Search

The sclerometer or Schmidt Rock Test Hammer has been broadly applied in geomorphology to estimate the strength of different rock types and to measure the degree of rock weathering. It has been proved that for a rock type, the rebound values are lower in weathered than in fresh rock surfaces. This evidence suggests that if there is any factor that

A. Feal-Pérez; R. Blanco-Chao; A. Pérez-Alberti; J. López-Bedoya; M. Valcárcel-Díaz

2009-01-01

112

Observation and Research on Strong Meteor Showers and Their Catastrophic Space Weather Events  

Microsoft Academic Search

During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to

Yue-Hua Ma; Pin-Xin Xu; Hai-Bin Zhao

2008-01-01

113

Evaluation of Greenland Ice Sheet Surface Climate in the HIRHAM Regional Climate Model Using Automatic Weather Station Data  

Microsoft Academic Search

The 1998 annual cycle and 1991-98 summer simulations of Greenland ice sheet surface climate are made with the 0.5°-horizontal resolution HIRHAM regional climate model of the Arctic. The model output is compared with meteorological and energy balance observations from 15 Greenland Climate Network automatic weather stations. The model reproduces the monthly average surface climate parameters, to a large extent within

Jason E. Box; Annette Rinke

2003-01-01

114

Mashup aggregation of citizen-scientists weather observations and application of OGC standards to weather data for Hydro-Meteorological Research needs  

NASA Astrophysics Data System (ADS)

The growing interest towards hydro-meteorological information (e.g. forecasts and actual weather conditions) shown by citizen-scientists and increasing affordability of automated weather stations foster the development of volunteers' weather networks. The citizen-scientists weather data collections often are shared online. In some cases, for example during meteorological extreme events, such semi-professional weather networks can provide an unprecedented amount of weather observations in addition to official weather networks data. These observational data are usually provided in real time, registered with some minute frequency and data collections encompass the spatial spreading and temporal continuity. Therefore, these datasets may be extremely valuable in areas with complex orography and reduced covering by institutional weather sensors. The significant obstacles in operating of citizen-scientists weather observations are the lack of well-established aggregation mechanism for data produced by various weather networks according to different data encoding, schemes and formats. Usually, large quantity and complexity of datasets requires the innovative approaches in data collections processing. This paper describes the designing of an application addressing the collection and integration of Hydro-Meteorological (HM) datasets, provided by citizen-scientists. The application is based on the mashup approach that allows combining different sources with similar type of information and designing new data representation. This approach suits the HM community requirements for geospatial data operating, including aggregation of different type of information spread online. The integration of different datasets urges for standards data representation. The OGC consortium developed internationally recognized standards for geospatial data. These standards include interfaces and encoding schemes. In this paper OGC standards were applied to citizen-scientists weather observations, to provide standard representation, easier data integration and post analysis.

Bedrina, Tatiana; Parodi, Antonio; Quarati, Alfonso; Clematis, Andrea

2013-04-01

115

Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization  

NASA Astrophysics Data System (ADS)

Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3-5 ?m thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ˜10 5 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the possibility of this amorphous layer on feldspar surface.

Zhu, Chen; Veblen, David R.; Blum, Alex E.; Chipera, Stephen J.

2006-09-01

116

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25°C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

William P. Inskeep; Edward A. Nater; Paul R. Bloom; Dirk S. Vandervoort; M. Susan Erich

1991-01-01

117

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

W. P. Inskeep; D. S. Vandervoort; E. A. Nater; P. R. Bloom; M. S. Erich

1991-01-01

118

The rate and causes of lunar space weathering: Insights from Lunar Reconnaissance Orbiter Wide Angle Camera ultraviolet observations  

NASA Astrophysics Data System (ADS)

Lunar Reconnaissance Orbiter Wide Angle Camera global ultraviolet and visible imaging provides a unique opportunity to examine the rate and causes of space weathering on the Moon. Silicates typically have a strong decrease in reflectance toward UV wavelengths (<~450 nm) due to strong bands at 250 nm and in the far UV. Metallic iron is relatively spectrally neutral, and laboratory spectra suggest that its addition to mature soils in the form of submicroscopic iron (also known as nanophase iron) flattens silicate spectra, significantly reducing spectral slope in the ultraviolet. Reflectance at ultraviolet wavelengths may be especially sensitive to the surface coatings that form due to exposure to space weathering because scattering from the surfaces of grains contributes a larger fraction to the reflectance spectrum at short wavelengths. We find that the UV slope (as measured by the 320/415 nm ratio) is a more sensitive measure of maturity than indexes based on visible and near-infrared wavelengths. Only the youngest features (less than ~100 Ma) retain a UV slope that is distinct from mature soils of the same composition. No craters >20 km have UV slopes that approach those observed in laboratory spectra of fresh lunar materials (powdered lunar rocks). While the 320/415 nm ratio increases by ~18% from powdered rocks to mature soils in laboratory samples, Giordano Bruno, the freshest large crater, only shows a 3% difference between fresh and mature materials. At the resolution of our UV data (400 m/pixel), we observe some small (<5 km) craters that show a ~14% difference in 320/415 nm ratio from their mature surroundings. UV observations show that Reiner Gamma has had significantly lower levels of space weathering than any of the Copernican craters we examined, and was the only region we found with a UV slope that approached laboratory values for fresh powdered rock samples. This is consistent with the hypothesis that its high albedo is due to magnetic shielding from solar wind sputtering effects. Furthermore the observation that all Copernican craters we examined show some degree of space weathering and the extreme immaturity of Reiner Gamma materials show that space weathering of the surface and the resultant modification of UV spectra proceeds at a fast rate and is dominated by solar wind sputtering. Comparisons of the UV trends on other airless bodies (i.e., asteroids and Mercury) may prove fruitful for understanding the relative rates and causes of space weathering across the inner solar system.

Denevi, B. W.; Robinson, M. S.; Sato, H.; Hapke, B. W.; McEwen, A. S.; Hawke, B. R.

2011-12-01

119

BPCDG: Breakpoint Climate Data Generator for WEPP Using Observed Standard Weather Data Sets  

Microsoft Academic Search

To test the overall performance of any new prediction tool, model parameters can be taken directly from observed data sets or generated using different interface mechanisms. This paper presents a relatively simple program, BPCDG (Breakpoint Climate Data Generator), which generates breakpoint climate data using observed standard weather data sets that can then be used as input for the Water Erosion

Zeleke Gete; Thomas Winter; Dennis Flanagan

120

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

SciTech Connect

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately 700 {angstrom} thick. The more calcic phase was preferentially weathered to average depths of 1,350 {angstrom} in excess of the more sodic phase, producing a corrugated surface. The surface roughness caused by preferential weathering of the more calcic phase affects the relative exposure of calcic and sodic phases to the XPS detector. A three-dimensional analysis of possible surface exposures was used to predict the influence of a corrugated surface on XPS measurements. Results showing preferential weathering of more calcic-rich lamellae and its effect on XPS spectra indicate the importance of understanding the micro-structure of feldspars used for laboratory weathering studies.

Inskeep, W.P.; Vandervoort, D.S. (Montana State Univ., Bozeman (United States)); Nater, E.A.; Bloom, P.R. (Univ. of Minnesota, St. Paul (United States)); Erich, M.S. (Univ. of Maine, Orono (United States))

1991-03-01

121

Weather Radar Performance at Long RangeA~éÂ---Simulated and Observed  

Microsoft Academic Search

A large set of high-vertical-resolution reflectivity profiles was used to simulate the performance of radars in the United Kingdom weather radar network. In particular, limitations in the estimation of surface precipitation due to incomplete beam filling and variability in the reflectivity profile were investigated. Marked seasonal variations in range performance were found and detection failures were shown to make a

M. Kitchen; P. M. Jackson

1993-01-01

122

Promotion of chemical weathering by higher plants: field observations on Hawaiian basalts  

Microsoft Academic Search

An electron microprobe and petrographic microscope were used to study the biota-rock interface beneath higher-plant communities and lichens, as well as unvegetated surfaces, on Hawaiian basalt flows ranging from a few years to several thousand years in age and currently receiving moderate to extremely high annual rainfall. We find dramatic (order of magnitude minimum) acceleration of weathering rates beneath vascular

M. Ford Cochran; Robert A. Berner

1996-01-01

123

Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroidal Space Weathering Studies  

NASA Astrophysics Data System (ADS)

Mercury's regolith, derived from the crustal bedrock, has been altered by a set of space weathering processes. Before we can interpret crustal composition, it is necessary to understand the nature of these surface alterations. The processes that space weather the surface are the same as those that form Mercury's exosphere (micrometeoroid flux and solar wind interactions) and are moderated by the local space environment and the presence of a global magnetic field. To comprehend how space weathering acts on Mercury's regolith, an understanding is needed of how contributing processes act as an interactive system. As no direct information (e.g., from returned samples) is available about how the system of space weathering affects Mercury's regolith, we use as a basis for comparison the current understanding of these same processes on lunar and asteroidal regoliths as well as laboratory simulations. These comparisons suggest that Mercury's regolith is overturned more frequently (though the characteristic surface time for a grain is unknown even relative to the lunar case), more than an order of magnitude more melt and vapor per unit time and unit area is produced by impact processes than on the Moon (creating a higher glass content via grain coatings and agglutinates), the degree of surface irradiation is comparable to or greater than that on the Moon, and photon irradiation is up to an order of magnitude greater (creating amorphous grain rims, chemically reducing the upper layers of grains to produce nanometer-scale particles of metallic iron, and depleting surface grains in volatile elements and alkali metals). The processes that chemically reduce the surface and produce nanometer-scale particles on Mercury are suggested to be more effective than similar processes on the Moon. Estimated abundances of nanometer-scale particles can account for Mercury's dark surface relative to that of the Moon without requiring macroscopic grains of opaque minerals. The presence of nanometer-scale particles may also account for Mercury's relatively featureless visible-near-infrared reflectance spectra. Characteristics of material returned from asteroid 25143 Itokawa demonstrate that this nanometer-scale material need not be pure iron, raising the possibility that the nanometer-scale material on Mercury may have a composition different from iron metal [such as (Fe,Mg)S]. The expected depletion of volatiles and particularly alkali metals from solar-wind interaction processes are inconsistent with the detection of sodium, potassium, and sulfur within the regolith. One plausible explanation invokes a larger fine fraction (grain size <45 ?m) and more radiation-damaged grains than in the lunar surface material to create a regolith that is a more efficient reservoir for these volatiles. By this view the volatile elements detected are present not only within the grain structures, but also as adsorbates within the regolith and deposits on the surfaces of the regolith grains. The comparisons with findings from the Moon and asteroids provide a basis for predicting how compositional modifications induced by space weathering have affected Mercury's surface composition.

Domingue, Deborah L.; Chapman, Clark R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Schriver, David; Trávní?ek, Pavel M.; Orlando, Thomas M.; Sprague, Ann L.; Blewett, David T.; Gillis-Davis, Jeffrey J.; Feldman, William C.; Lawrence, David J.; Ho, George C.; Ebel, Denton S.; Nittler, Larry R.; Vilas, Faith; Pieters, Carle M.; Solomon, Sean C.; Johnson, Catherine L.; Winslow, Reka M.; Helbert, Jörn; Peplowski, Patrick N.; Weider, Shoshana Z.; Mouawad, Nelly; Izenberg, Noam R.; McClintock, William E.

2014-04-01

124

Local topography of Mars and its relationship to surface weathering processes  

NASA Technical Reports Server (NTRS)

There is a growing body of evidence in favor of the importance of aqueous sedimentary processes on Mars. It is important to understand the role that surface weathering processes have played in the development of the present morphology of the Martian surface. Such an understanding is important not only for its relevance to the study of volatile sources and sinks on Mars through time, but also for its relevance to Martian geologic and tectonic history. Starting in the fall of this year, the Mars Observer Laser Altimeter will begin sending back to Earth data on the topography of Mars that is of a higher quality than most of the topography data available for the Earth. This data will be invaluable, not only for understanding global and large-scale regional processes and landforms on Mars, but also for the study of local and smaller-scale regional processes and landforms. Digital topography is an important part of geologic and geomorphic studies, useful in distinguishing between different lithologies and between different types of weathering. Digital topography data may be used to study a wide variety of local and regional-scale landforms, including valleys, sand dunes, lava flows, landslides, and slopes. Topography data are also essential to the analysis of spectral response patterns, especially in areas of high topographic relief. Geomorphic classification can be significantly improved by the addition of topographic information.

Schaefer, M. W.

1993-01-01

125

Evolution of Titan's outer icy shell: Role of ocean crystallization and surface weathering  

NASA Astrophysics Data System (ADS)

The Cassini-Huygens mission has brought evidences for an internal ocean lying under an outer ice shell. The structure and evolution of the outer ice shell and of the internal ocean are essential to understand Titan's surface morphology as well as its atmosphere evolution. The observed shape and the gravity field of Titan provide information on the present-day structure of the H2O mantle, in terms of ocean/ice interface depth and crustal density. By modeling consistently topography and gravity data, we have quantified the amplitudes of ice shell thickness and/or crustal density variations. Moreover, we have constrained the possible viscosity structure of the outer shell and thermal gradients by modeling the topography relaxation rate. Lateral variations in the thickness of the outer ice shell may be explained by heterogeneous ocean crystallization, while surface weathering by liquid hydrocarbons may generate surface erosion and crustal alteration. To determine how these processes affect Titan's dynamics, we model heat and mass transfers between the internal ocean, the ice shell and the atmosphere and we determine the time evolution of long-wavelength topography and surface stress patterns for different evolutionary scenarios. Finally, we compare our predicted maps of surface stress and heat flux anomalies with the global repartition of the morphological features observed by VIMS and Radar.

Lefevre, A.; Tobie, G.; Amit, H.; Cadek, O.; Choblet, G.; Le Mouelic, S.; Mitri, G.; Sotin, C.

2013-12-01

126

Severe weather observed by infrasound, lidar and airglow measurements during the ARISE OHP Campaign  

NASA Astrophysics Data System (ADS)

In the frame of the ARISE project dedicated to provide a new 3D image of the atmospheric dynamics in the different atmospheric layers, an observation campaign using infrasound, lidar and airglow measurements started in July 2012 in the Observatoire de Haute Provence. This paper is dedicated to present first observations of severe weather, including sprite producing thunderstorms and a tornado. The study considers acoustic waves but also focuses on gravity waves at the origin of larger scale disturbances. The coupling between atmospheric layers during these events is analyzed using numerical weather simulations. The presentation discusses the benefits of the use of the three different technologies for a better description of these events.

Blanc, Elisabeth; Farges, Thomas; Le Pichon, Alexis; Hauchecorne, Alain; Wüst, Sabine; Heinrich, Philippe; Keckhut, Philippe; Costantino, Lorenzo; Bittner, Michael; Schmidt, Carsten

2013-04-01

127

Laboratory Simulations of Space Weathering of Asteroid Surfaces by Solar Wind Ions.  

NASA Astrophysics Data System (ADS)

Studies into the formation of the terrestrial planets rely on the analysis of asteroids and meteorites. Asteroids are solar system remnants from the planetary formation period. By characterizing their mineralogical composition we can better constrain the formation and evolution of the inner planets.Remote sensing is the primary means for studying asteroids. Sample return missions, such as Hayabusa, are complex and expensive, hence we rely on asteroid reflectance spectra to determine chemical composition. Links have been made and debated between meteorite classes and asteroid types [1, 2]. If such relationships can be confirmed, then meteorites would provide a low cost asteroid sample set for study. However, a major issue in establishing this link is the spectral differences between meteorite samples and asteroid surfaces. The most commonly invoked explanation for these differences is that the surfaces of asteroids are space weathered [2, 3]. The dominant mechanism for this weathering is believed to be solar-wind ion irradiation [2, 4, 5]. Laboratory simulations of space weathering have demonstrated changes in the general direction required to alter spectra from unweathered meteorite samples to asteroid observations [3, 6 -10], but many open questions remain and we still lack a comprehensive understanding. We propose to explore the alleged connection of ordinary chondrite (OC) meteorites to S-type asteroids through a series of systematic laboratory simulations of solar-wind space weathering of asteroid surface materials. Here we describe the issue in more detail and describe the proposed apparatus. [1] Chapman C. R. (1996) Meteorit. Planet. Sci., 31, 699-725. [2] Chapman C. R. (2004), Annu. Rev. Earth Planet. Sci., 32, 539-567. [3] Hapke B. (2001) J. Ge-ophys. Res., 106, 10039-10074. [4] Pieters C.M. et al. (2000) Meteorit. Planet. Sci., 35, 1101-1107. [5] Ver-nazza P. et al. (2009) Nature, 458, 993-995. [6] Stra-zulla G. et al. (2005) Icarus, 174, 31-35 (2005). [7] Brunetto R and Strazzulla G (2005) Icarus, 179, 265-273. [8] Marchi S et al. (2005) Astron. Astrophys., 443, 769-775. [9] Loeffler M. J. et al. (2009) J. Geo-phys. Res., 114, E03003. [10] Fu X. et al. (2012) Ica-rus, 219, 630-640

Miller, Kenneth A.; De Ruette, Nathalie; Harlow, George; Domingue, Deborah L.; Savin, Daniel Wolf

2014-06-01

128

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science  

Microsoft Academic Search

We often look ``through a glass, darkly'' at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers

J. F. Cooper; R. E. Hartle; E. C. Sittler; M. A. McGrath; C. J. Alexander; J. B. Dalton; D. Pascu; C. Paranicas; C. Hibbitts; M. E. Hill; P. D. Cooper; R. E. Johnson; T. A. Cassidy; T. M. Orlando; L. J. Lanzerotti; N. A. Schwadron; K. D. Retherford; R. I. Kaiser; F. Leblanc; S. J. Sturner; R. M. Killen

2009-01-01

129

Plymouth State Weather Center  

NSDL National Science Digital Library

The Plymouth State Weather Center provides a variety of weather information, including a tropical weather menu with current and archived data on tropical depressions, storms, or hurricanes in the Atlantic or Eastern Pacific Oceans. An interactive Weather Product Generator allows students to make their own surface data maps and meteograms (24-hour summaries of weather at a specific location), and view satellite imagery. There are also interactive weather maps for the U.S., Canada, and Alaska that display the latest observations, and text servers which provide current written observations for New England and North America. A set of past and current weather data products provides information on minimum and maximum temperatures, wind chill, and heat index. In addition, there are collections of satellite loops/movies, radar/lightning images, loops, and movies, and a set of tutorials on clouds, the sun and its effects on the environment, and balanced atmospheric flows.

130

Space weathered rims found on the surfaces of the Itokawa dust particles  

NASA Astrophysics Data System (ADS)

On the basis of observations using Cs-corrected STEM, we identified three types of surface modification probably formed by space weathering on the surfaces of Itokawa particles. They are (1) redeposition rims (2-3 nm), (2) composite rims (30-60 nm), and (3) composite vesicular rims (60-80 nm). These rims are characterized by a combination of three zones. Zone I occupies the outermost part of the surface modification, which contains elements that are not included in the unchanged substrate minerals, suggesting that this zone is composed of sputter deposits and/or impact vapor deposits originating from the surrounding minerals. Redeposition rims are composed only of Zone I and directly attaches to the unchanged minerals (Zone III). Zone I of composite and composite vesicular rims often contains nanophase (Fe,Mg)S. The composite rims and the composite vesicular rims have a two-layered structure: a combination of Zone I and Zone II, below which Zone III exists. Zone II is the partially amorphized zone. Zone II of ferromagnesian silicates contains abundant nanophase Fe. Radiation-induced segregation and in situ reduction are the most plausible mechanisms to form nanophase Fe in Zone II. Their lattice fringes indicate that they contain metallic iron, which probably causes the reddening of the reflectance spectra of Itokawa. Zone II of the composite vesicular rims contains vesicles. The vesicles in Zone II were probably formed by segregation of solar wind He implanted in this zone. The textures strongly suggest that solar wind irradiation damage and implantation are the major causes of surface modification and space weathering on Itokawa.

Noguchi, Takaaki; Kimura, Makoto; Hashimoto, Takahito; Konno, Mitsuru; Nakamura, Tomoki; Zolensky, Michael E.; Okazaki, Ryuji; Tanaka, Masahiko; Tsuchiyama, Akira; Nakato, Aiko; Ogami, Toshinori; Ishida, Hatsumi; Sagae, Ryosuke; Tsujimoto, Shinichi; Matsumoto, Toru; Matsuno, Junya; Fujimura, Akio; Abe, Masanao; Yada, Toru; Mukai, Toshifumi; Ueno, Munetaka; Okada, Tatsuaki; Shirai, Kei; Ishibashi, Yukihiro

2014-02-01

131

Rates of oxidative weathering on the surface of Mars  

NASA Astrophysics Data System (ADS)

A model of acid weathering is proposed for the iron-rich basalts on Mars. Aqueous oxidation of iron sulfides released SO4(2-) and H(+) ions that initiated the dissolution of basaltic ferromagnesian silicates and released Fe(2+) ions. The Fe(2+) ions eventually underwent ferrolysis reactions and produced insoluble hydrous ferric oxide phases. Measurements of the time-dependence of acid weathering reactions show that pyrrhotite is rapidly converted to pyrite plus dissolved ferrous iron, the rate of pyrite formation decreasing with rising pH and lower temperatures. On Mars, oxidation rates of dissolved Fe(2+) ions in equatorial melt-waters in contact with the atmosphere are estimated to lie in the range 0.3-3.0 ppb Fe/yr over the pH range 2 to 6. Oxidation of Fe(2+) ions is estimated to be extremely slow in brine eutectic solutions that might be present on Mars and to be negligible in the frozen regolith.

Burns, R. G.; Fisher, D. S.

1993-02-01

132

Optimal Sites for Supplementary Weather Observations: Simulation with a Small Model  

Microsoft Academic Search

ABSTRACT Anticipating the opportunity to make,supplementary,observations at locations that can depend upon the current weather situation, the question is posed as to what strategy should be adopted to select the locations, if the greatest improvement in analyses and forecasts is to be realized. To seek a preliminary answer, the authors introduce a model consisting of 40 ordinary differential equations, with

Edward N. Lorenz; Kerry A. Emanuel

1998-01-01

133

JPL's Real-Time Weather Processor project (RWP) metrics and observations at system completion  

NASA Technical Reports Server (NTRS)

As an integral part of the overall upgraded National Airspace System (NAS), the objective of the Real-Time Weather Processor (RWP) project is to improve the quality of weather information and the timeliness of its dissemination to system users. To accomplish this, an RWP will be installed in each of the Center Weather Service Units (CWSUs), located in 21 of the 23 Air Route Traffic Control Centers (ARTCCs). The RWP System is a prototype system. It is planned that the software will be GFE and that production hardware will be acquired via industry competitive procurement. The ARTCC is a facility established to provide air traffic control service to aircraft operating on Instrument Flight Rules (IFR) flight plans within controlled airspace, principally during the en route phase of the flight. Covered here are requirement metrics, Software Problem Failure Reports (SPFRs), and Ada portability metrics and observations.

Loesh, Robert E.; Conover, Robert A.; Malhotra, Shan

1990-01-01

134

Energy balance of a glacier surface: Analysis of automatic weather station data from the Morteratschgletscher, Switzerland  

Microsoft Academic Search

We describe and analyze a complete 1-yr data set from an automatic weather station (AWS) located on the snout of the Morteratschgletscher, Switzerland. The AWS stands freely on the glacier surface and measures pressure, windspeed, wind direction, air temperature and humidity, incoming and reflected solar radiation, incoming and outgoing longwave radiation, snow temperature, and change in surface height (giving melt

J. Oerlemans; E. J. Klok

2002-01-01

135

Numerical weather prediction as a surrogate for climate observations in practical applications  

NASA Astrophysics Data System (ADS)

Climate data is used in many practical applications including energy demand estimations for heating and cooling, agricultural applications, risk assessment, and many more. The required climate data is only available if meteorological observations exist at a given location. In this study, the possibility of replacing long observational records with a few years of numerical weather forecast data is investigated for practical applications requiring temperature data. Observational data from 1980-2010, measured at 700 weather stations in Central Europe are used together with model forecasts of the years 2008-2010. Depending on the station, forecast data capture 90-110% of the standard deviation observed for daily mean and maximum temperatures and slightly less for minimum temperature. Heating and cooling degree days can be estimated with an error of 5-15% in climates where they have a relevance. Based on model data, maps of heating and cooling degree days are computed and the regional uncertainties are quantified using the observational data. The results suggest that numerical weather forecast data can be used for certain practical applications, either as a surrogate of observational data or for quite reliable estimates in locations with no observations.

Müller, M. D.; Parlow, E.

2013-02-01

136

Weathering Animation  

NSDL National Science Digital Library

Weathering is the term that describes all the processes that break down rocks in the environment near the Earth's surface. This module will help you to understand two weathering processes: mechanical and chemical.

2002-01-01

137

Extracting fair-weather data from atmospheric electric-field observations at Syowa Station, Antarctica  

NASA Astrophysics Data System (ADS)

At Syowa Station (69.0°S, 39.6°E), located on East Ongul Island near the continent of Antarctica, atmospheric electric-field observations started in 1968 and had been carried out intermittently. An improved electric-field mill at Syowa Station had and obtained better-quality atmospheric electric-field data from February 2005 to January 2006. After a 1-year interruption, the observations resumed in January 2007. The atmospheric electric-field data from Syowa Station are often contaminated due to local disturbances caused by near-ground meteorological phenomena. We examined correlations between the atmospheric electric field and near-ground weather from February 2005 to January 2006 and from February 2007 to January 2008, and proposed a criterion to extract “fair-weather” electric-field data based on wind speed and cloud coverage data. The diurnal variation of fair-weather data in January followed the shape of the so-called Carnegie curve. Fair-weather data obtained during a substorm showed some correspondence between the atmospheric electric field and variations in the geomagnetic field. This newly developed extraction method may enable the use of atmospheric electric-field data for studying the solar terrestrial environment.

Minamoto, Yasuhiro; Kadokura, Akira

2011-09-01

138

Hubble Observes Surface of Titan  

NASA Technical Reports Server (NTRS)

Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.

Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.

Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.

Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much thicker.

Smith's group used the Hubble Space Telescope's WideField/Planetary Camera 2 at near-infrared wavelengths (between .85 and 1.05 microns). Titan's haze is transparent enough in this wavelength range to allow mapping of surface features according to their reflectivity. Only Titan's polar regions could not be mapped this way, due to the telescope's viewing angle of the poles and the thick haze near the edge of the disk. Their image-resolution (that is, the smallest distance seen in detail) with the WFPC2 at the near-infrared wavelength is 360 miles. The 14 images processed and compiled into the Titan surface map were as 'noise' free, or as free of signal interference, as the space telescope allows, Smith said.

Titan makes one complete orbit around Saturn in 16 days, roughly the duration of the imaging project. Scientists have suspected that Titan's rotation also takes 16 days, so that the same hemisphere of Titan always faces Saturn, just as the same hemisphere of the Earth's moon always faces the Earth. Recent observations by Lemmon and colleagues at the University of Arizona confirm this true.

It's too soon to conclude much about what the dark and bright areas in the Hubble Space Telescope images are -- continents, oceans, impact craters or other features, Smith said. Scientists have long suspected that Titan's surface was covered with a global ehtane-methane ocean. The new images show that there is at least some solid surface.

Smith's team made a total 50 images of Titan last month in their program, a project to search for small scale features in Titan's lower atmosphere and surface. They have yet to analyze images for information about Titan's clouds and winds. That analysis could help explain if the bright areas are major impact craters in the frozen water ice-and-rock or higher-altitude features.

The images are important information for the Cassini mission, which is to launch a robotic spacecraft on a 7-year journey to Saturn in October 1997. About three weeks before Cassini's first flyby

1994-01-01

139

Observation and Research on Strong Meteor Showers and Their Catastrophic Space Weather Events  

NASA Astrophysics Data System (ADS)

During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to 2003) fully verifies that the non-sporadic periodic strong meteor shower may lead to catastrophic space weather events. Preliminary identification is made of the following: the mechanism of formation of strong meteor showers, the law of occurrence of the fbEs abnormal peak and serious safety hazards for astronavigation. Also discussed in this paper are the evolutionary process of cometary dust, the law of occurrence and loss of cosmic dust storm and the mechanism of maintaining cosmic dust in the mid-latitude Es layer.

Ma, Yue-hua; He, You-wen; Xu, Pin-xin; Zhao, Hai-bin

2008-04-01

140

Conversion of bedrock to soil and feedback processes between the surface and the weathering front in a deeply weathered regolith, Central Sri Lankan Highlands  

NASA Astrophysics Data System (ADS)

In the Sri Lankan highlands denudation rates and chemical weathering rates represent the low-end-member in global weathering rates [1, 2]. Here we explore the causes for these low rates by a detailed soil-mineralogical study of a highly weathered deep saprolite profile developed from charnockite bedrock. Spheroidal weathering of the bedrock characterized the weathering front where rounded corestones are produced at the rock-saprolite interface. The first mineral attacked by weathering was found to be pyroxene but plagioclase is the first mineral depleted to near-completion at the corestone-saprolite-boundary. Weathering of pyroxene is initiated by in situ iron oxidation, leading to an increase of porosity due to micro-cracking [3]. The accrued micro cracks allow for fluid transport and the dissolution of biotite and plagioclase. The strong plagioclase weathering leads to formation of high secondary porosity over a small distance and the final disaggregation of bedrock to saprolite. Sequential extraction showed that the first secondary phases are amorphous oxides from which secondary minerals (gibbsite, kaolinite, goethite and minor amounts of smectites) precipitate. Modeling of the strain formation due to increasing volume during iron oxidation in pyroxene and biotite showed that spheroidal weathering can be explained with this process only if the formation of secondary porosity, due to a negative volume budget during primary mineral weathering to secondary phases, occurs. As oxidation is the first occurring reaction, O2 is a rate limiting factor for chemical weathering in this setting. Hence the supply of oxygen and the consumption at depth connects processes at the weathering front with those at the surface as a feedback mechanism. Advective and diffusive transport modeling shows that the feedback will be much more pronounced with dominating diffusive transport. Due to the low porosity of the bedrock the O2 transport in the pristine bedrock occurs via diffusion. The slow weathering rate is, beside tectonic quiescence, related to this feedback and to lithological factors such as low porosity and the amount of Fe-bearing primary minerals. 1. Hewawasam, T., et al., Slow advance of the weathering front during deep, supply-limited saprolite formation in the tropical Highlands of Sri Lanka. Geochimica et Cosmochimica Acta, 2013. 118: p. 202-230. 2. von Blanckenburg, F., T. Hewawasam, and P. Kubik, Cosmogenic nuclide evidence for low weathering and denudation in the wet tropical Highlands of Sri Lanka. J. Geoph. Res., 2004. 109: p. doi10.1029/2003JF000049. 3. Buss, H.L., et al., Weathering of the Rio Blanco quartz diorite, Luquillo Mountains, Puerto Rico: Coupling oxidation, dissolution, and fracturing. Geochimica et Cosmochimica Acta, 2008. 72(18): p. 4488-4507.

Behrens, Ricarda; Bouchez, Julien; Schuessler, Jan A.; Dultz, Stefan; Hewawasam, Tilak; von Blanckenburg, Friedhelm

2014-05-01

141

The Main Pillar: Assessment of Space Weather Observational Asset Performance Supporting Nowcasting, Forecasting and Research to Operations  

NASA Astrophysics Data System (ADS)

Sporadically, the Sun unleashes severe magnetic activity into the heliosphere. The specific solar/heliospheric phenomena and their effects on humans, technology and the wider geospace environment include a) high-intensity emissions from the Sun causing radio blackouts and (surface) charging, b) particle acceleration in the solar corona leading to high dose rates of ionizing radiation in exposed materials that can trigger single event upsets in electronic components of space hardware, or temporal/permanent damage in tissue, c) arrivals of fast-moving coronal mass ejections with embedded enhancements of magnetic fields that can cause strong ionospheric disturbances affecting radio communications and induce out-of-spec currents in power lines near the surface. Many of the effects could now be forecast with higher fidelity than ever before. However, forecasting critically depends upon availability of timely and reliable observational data. It is therefore crucial to understand how observational assets perform during periods of severe space weather. This paper analyzes and documents the status of the existing and upcoming observational capabilities for forecasting, and discusses how the findings may impact space weather research and its transition to operations.

Posner, A.; Hesse, M.; St. Cyr, C.

2012-12-01

142

Ensemble Data Assimilation to Characterize Surface-Layer Errors In Numerical Weather Prediction Models  

NASA Astrophysics Data System (ADS)

Experiments with the single-column implementation of the Weather Research and Forecasting mesoscale model provide a basis for deducing land-atmosphere coupling errors in the model. Coupling occurs both through heat and moisture fluxes through the land-atmosphere interface and roughness sub-layer, and turbulent heat, moisture, and momentum fluxes through the atmospheric surface layer. This work primarily addresses the turbulent fluxes, which are parameterized following Monin-Obukhov similarity theory applied to the atmospheric surface layer. By combining ensemble data assimilation and parameter estimation, the model error can be characterized. Ensemble data assimilation of 2-m temperature and water vapor mixing ratio, and 10-m wind components, forces the model to follow observations during a month-long simulation for a column over the well-instrumented ARM Central Facility near Lamont, OK. One-hour errors in predicted observations are systematically small but non-zero, and the systematic errors measure bias as a function of local time of day. Analysis increments for state elements nearby (15-m AGL) can be too small or have the wrong sign, indicating systematically biased covariances and model error. Experiments using the ensemble filter to objectively estimate a parameter controlling the thermal land-atmosphere coupling show that the parameter adapts to offset the model errors, but that the errors cannot be eliminated. Results suggest either structural error or further parametric error that may be difficult to estimate. Experiments omitting atypical observations such as soil and flux measurements lead to qualitatively similar deductions, showing potential for assimilating common in-situ observations as an inexpensive framework for deducing and isolating model errors. We finish by presenting recent results from a deeper examination of the second-moment ensemble statistics, which demonstrate the effect of assimilation on the coupling through the stability function in the atmospheric surface layer scheme.

Hacker, Joshua; Angevine, Wayne

2013-04-01

143

Total Lightning Observations of Extreme Weather Events over the Contiguous United States  

NASA Technical Reports Server (NTRS)

The overall objective is to investigate total lightning characteristics of extreme weather events over the contiguous United States (CONUS) using TRMM (Tropical Rainfall Measuring Mission) LIS (Lightning Image Sensor) and OTD (Optical Transient Detector) satellite observations. A large LIS (10+ years) and OTD (5 years) data base is available to study the instantaneous total or cloud-to-ground (CG) plus intracloud (IC) lightning characteristics of extreme weather events. More specifically, the LIS and OTD data are combined with National Lightning Detection Network (NLDN) observations to examine the total and CG lightning flash rate and density, the IC:CG ratio, and positive CG percentage. These instantaneous lightning characteristics can be used for basic science studies to better understand the physical and dynamical linkages between lightning and precipitation and their environmental controls. They can also provide a first-look of extreme weather events leading up to future satellite observations (e.g., NOAA GOES-R Geostationary Lightning Mapper [GLM]) for use in climate studies and the short-term prediction and warning process. Extreme weather events are defined by the NOAA Storm Data reports of tornadoes, large hail (at least 0.75 inch) and strong straight-line winds (at least 50 kts). Over CONUS, there are over 70,000 severe storm reports in the TRMM spatial domain (< 35 N) from 1998-2007 and over 100,000 storm reports in the OTD spatial domain (5/1995-4/2000). Temporal co-location is on the order of 1% (i.e., 1000 s of coincident overpasses), providing a statistically significant sample of instantaneous total lightning properties. This instantaneous behavior of lightning in extreme weather is then compared to that of typical thunderstorm events, or randomly sampled LIS/OTD events in which the extreme events have been eliminated from the population. Results describing the instantaneous behavior of total lightning within a large sample of extreme and typical thunderstorms over CONUS will be presented. When possible, coincident VHF lightning observations from the ground-based Northern Alabama Lightning Mapping Array (LMA) are compared to the LIS/OTD optical lightning signatures, providing a validation source for instantaneous space-based optical lightning properties and a means to extend lightning inferences over the life-cycle of extreme weather.

Carey, Lawrence D.; Petersen, Walter A.; Christian, Hugh J.

2008-01-01

144

Total Lightning Observations of Extreme Weather Events over the Contiguous United States  

NASA Astrophysics Data System (ADS)

The overall objective is to investigate total lightning characteristics of extreme weather events over the contiguous United States (CONUS) using TRMM (Tropical Rainfall Measuring Mission) LIS (Lightning Image Sensor) and OTD (Optical Transient Detector) satellite observations. A large LIS (10+ years) and OTD (5 years) data base is available to study the instantaneous total or cloud-to-ground (CG) plus intracloud (IC) lightning characteristics of extreme weather events. More specifically, the LIS and OTD data are combined with National Lightning Detection Network (NLDN) observations to examine the total and CG lightning flash rate and density, the IC:CG ratio, and positive CG percentage. These instantaneous lightning characteristics can be used for basic science studies to better understand the physical and dynamical linkages between lightning and precipitation and their environmental controls. They can also provide a first-look of extreme weather events leading up to future satellite observations (e.g., NOAA GOES-R Geostationary Lightning Mapper [GLM]) for use in climate studies and the short-term prediction and warning process. Extreme weather events are defined by the NOAA Storm Data reports of tornadoes, large hail (at least 0.75 inch) and strong straight-line winds (at least 50 kts). Over CONUS, there are over 70,000 severe storm reports in the TRMM spatial domain (< 35 degrees N) from 1998-2007 and over 100,000 storm reports in the OTD spatial domain (5/1995-4/2000). Temporal co-location is on the order of 1% (i.e., 1000's of coincident overpasses), providing a statistically significant sample of instantaneous total lightning properties. This instantaneous behavior of lightning in extreme weather is then compared to that of typical thunderstorm events, or randomly sampled LIS/OTD events in which the extreme events have been eliminated from the population. Results describing the instantaneous behavior of total lightning within a large sample of extreme and typical thunderstorms over CONUS will be presented. When possible, coincident VHF lightning observations from the ground-based Northern Alabama Lightning Mapping Array (LMA) are compared to the LIS/OTD optical lightning signatures, providing a validation source for instantaneous space-based optical lightning properties and a means to extend lightning inferences over the life-cycle of extreme weather.

Carey, L. D.; Petersen, W. A.; Christian, H. J.

2008-12-01

145

Weathering pits as indicators of the relative age of granite surfaces in the Cairngorm mountains, Scotland  

USGS Publications Warehouse

Weathering pits 1-140 cm deep occur on granite surfaces in the Cairngorms associated with a range of landforms, including tors, glacially exposed slabs, large erratics and blockfields. Pit depth is positively correlated with cosmogenic exposure age, and both measures show consistent relationships on individual rock landforms. Rates of pit deepening are non-linear and a best fit is provided by the sigmoidal function D = b1+ exp(b2+b3/t). The deepest pits occur on unmodified tor summits, where 10 Be exposure ages indicate that surfaces have been exposed to weathering for a minimum of 52-297 ka. Glacially exposed surfaces with pits 10-46 cm deep have given 10 Be exposure durations of 21-79 ka, indicating exposure by glacial erosion before the last glacial cycle. The combination of cosmogenic exposure ages with weathering pit depths greatly extends the area over which inferences can be made regarding the ages of granite surfaces in the Cairngorms. Well-developed weathering pits on glacially exposed surfaces in other granite areas are potential indicators of glacial erosion before the Last Glacial Maximum. ?? Swedish Society for Anthropology and Geography.

Hall, A. M.; Phillips, W. M.

2006-01-01

146

Uijongbu, Camp LaGuardia, Korea, Limited Surface Observations Climatic Summary (LISOCS).  

National Technical Information Service (NTIS)

This report is similar to a Revised Uniform Summary of Surface Weather Observations (RUSSWO) except the summary generated is from data observed at limited-duty observation sites. This summary is blocked based on the normal hours of observation and only th...

1983-01-01

147

Modelling convective severe weather occurrence using observations, reanalysis data and decadal climate predictions  

NASA Astrophysics Data System (ADS)

Observations of local severe convective events can be combined with atmospheric reanalyses to compute severe weather probability as a function of parameters characterizing the local state of the atmosphere. Using ERA-Interim reanalysis data and observations from the European Severe Weather Database, we have investigated several ways to express the probability of large hail, tornadoes, flash floods or wind gusts as a function of parameters such as convective available potential energy, vertical wind shear and precipitation. Our attempts include fitting analytic functions, using smoothers of various kinds, and binning the data within the multidimensional parameter space according to various algorithms. We imposed that any difference between binned observations and the modelled probability function be insignificant at the 95% confidence level. Further tests of robustness of the model were conducted. A probability function fulfilling this criterion was selected and subsequently applied to the ERA-Interim data as well as to predictions of the decadal forecasting system developed in the MiKlip programme. We investigated climatic and modelled past and future trends of severe convective weather. We will present the (preliminary) results of that effort.

Pistotnik, Georg; Groenemeijer, Pieter

2014-05-01

148

Combining solar science and asteroid science with the space weather observation network (SWON)  

NASA Astrophysics Data System (ADS)

The peculiarity of space weather for Earth orbiting satellites, air traffic and power grids on Earth and especially the financial and operational risks posed by damage due to space weather, underline the necessity of space weather observation. The importance of such observations is even more increasing due to the impending solar maximum. In recognition of this importance we propose a mission architecture for solar observation as an alternative to already published mission plans like Solar Probe (NASA) or Solar Orbiter (ESA). Based upon a Concurrent Evaluation session in the Concurrent Engineering Facility of the German Aerospace Center, we suggest using several spacecraft in an observation network. Instead of placing such spacecraft in a solar orbit, we propose landing on several asteroids, which are in opposition to Earth during the course of the mission and thus allow observation of the Sun's far side. Observation of the far side is especially advantageous as it improves the warning time with regard to solar events by about 2 weeks. Landing on Inner Earth Object (IEO) asteroids for observation of the Sun has several benefits over traditional mission architectures. Exploiting shadowing effects of the asteroids reduces thermal stress on the spacecraft, while it is possible to approach the Sun closer than with an orbiter. The closeness to the Sun improves observation quality and solar power generation, which is intended to be achieved with a solar dynamic system. Furthermore landers can execute experiments and measurements with regard to asteroid science, further increasing the scientific output of such a mission. Placing the spacecraft in a network would also benefit the communication contact times of the network and Earth. Concluding we present a first draft of a spacecraft layout, mission objectives and requirements as well as an initial mission analysis calculation.

Maiwald, Volker; Weiß, André; Jansen, Frank

2012-12-01

149

Motorway speeds in wet weather: the comparative influence of porous and conventional asphalt surfacings  

Microsoft Academic Search

This paper examines motorists’ speeds in wet weather compared with non-hazardous dry conditions (the control) for two separate survey locations on the M4 motorway, south Wales. One site was surfaced with conventional asphalt, whilst the other location had a porous asphalt wearing course. The aim of this study is to establish whether drivers compensate for the additional risks posed in

Julia B Edwards

2002-01-01

150

Space-weather Parameters for 1,000 Active Regions Observed by SDO/HMI  

NASA Astrophysics Data System (ADS)

We present statistical studies of several space-weather parameters, derived from observations of the photospheric vector magnetic field by the Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory, for a thousand active regions. Each active region has been observed every twelve minutes during the entirety of its disk passage. Some of these parameters, such as energy density and shear angle, indicate the deviation of the photospheric magnetic field from that of a potential field. Other parameters include flux, helicity, field gradients, polarity inversion line properties, and measures of complexity. We show that some of these parameters are useful for event prediction.

Bobra, M.; Liu, Y.; Hoeksema, J. T.; Sun, X.

2013-12-01

151

On predicting the life of polyethylene spacer-cable eroded by surface discharges in wet weather  

Microsoft Academic Search

As part of a study to evaluate the feasibility of uprating existing 15 kV spacer-cable systems to 34.5 kV, a method was developed for predicting the life of the polyethylene cable which may be eroded by electrical surface discharges in wet weather. The prediction method considers the changes in spacer surface resistance and the resulting electrical stress on the polyethylene

R. T. Harrold; T. W. Dakin

1976-01-01

152

Mars surface weathering products and spectral analogs: Palagonites and synthetic iron minerals  

NASA Technical Reports Server (NTRS)

There are several hypotheses regarding the formation of Martian surface fines. These surface fines are thought to be products of weathering processes occurring on Mars. Four major weathering environments of igneous rocks on Mars have been proposed; (1) impact induced hydrothermal alterations; (2) subpermafrost igneous intrusion; (3) solid-gas surface reactions; and (4) subaerial igneous intrusion over permafrost. Although one or more of these processes may be important on the Martian surface, one factor in common for all these processes is the reaction of solid or molten basalt with water (solid, liquid, or gas). These proposed processes, with the exception of solid-gas surface reactions, are transient processes. The most likely product of transient hydrothermal processes are layer silicates, zeolites, hydrous iron oxides and palagonites. The long-term instability of hydrous clay minerals under present Martian conditions has been predicted; however, the persistence of such minerals due to slow kinetics of dehydration, or entrapment in permafrost, where the activity of water is high, can not be excluded. Anhydrous oxides of iron (e.g., hematite and maghemite) are thought to be stable under present Martian surface conditions. Oxidative weathering of sulfide minerals associated with Martian basalts has been proposed. Weathering of sulfide minerals leads to a potentially acidic permafrost and the formation of Fe(3) oxides and sulfates. Weathering of basalts under acidic conditions may lead to the formation of kaolinite through metastable halloysite and metahalloysite. Kaolinite, if present, is thought to be a thermodynamically stable phase at the Martian surface. Fine materials on Mars are important in that they influence the surface spectral properties; these fines are globally distributed on Mars by the dust storms and this fraction will have the highest surface area which should act as a sink for most of the absorbed volatiles near the surface of Mars. Therefore, the objectives of this study were to: (1) examine the fine fraction mineralogy of several palagonitic materials from Hawaii; and (2) compare spectral properties of palagonites and submicron sized synthetic iron oxides with the spectral properties of the Martian surface.

Golden, D. C.; Ming, D. W.; Morris, R. V.; Lauer, H. V., Jr.

1992-01-01

153

A High-Resolution 3D Weather Radar, MSG, and Lightning Sensor Observation Composite  

NASA Astrophysics Data System (ADS)

Within the research group 'Object-based Analysis and SEamless prediction' (OASE) of the Hans Ertel Centre for Weather Research programme (HerZ), a data composite containing weather radar, lightning sensor, and Meteosat Second Generation observations is being developed for the use in object-based weather analysis and nowcasting. At present, a 3D merging scheme combines measurements of the Bonn and Jülich dual polarimetric weather radar systems (data provided by the TR32 and TERENO projects) into a 3-dimensional polar-stereographic volume grid, with 500 meters horizontal, and 250 meters vertical resolution. The merging takes into account and compensates for various observational error sources, such as attenuation through hydrometeors, beam blockage through topography and buildings, minimum detectable signal as a function of noise threshold, non-hydrometeor echos like insects, and interference from other radar systems. In addition to this, the effect of convection during the radar 5-minute volume scan pattern is mitigated through calculation of advection vectors from subsequent scans and their use for advection correction when projecting the measurements into space for any desired timestamp. The Meteosat Second Generation rapid scan service provides a scan in 12 spectral visual and infrared wavelengths every 5 minutes over Germany and Europe. These scans, together with the derived microphysical cloud parameters, are projected into the same polar stereographic grid used for the radar data. Lightning counts from the LINET lightning sensor network are also provided for every 2D grid pixel. The combined 3D radar and 2D MSG/LINET data is stored in a fully documented netCDF file for every 5 minute interval, and is made ready for tracking and object based weather analysis. At the moment, the 3D data only covers the Bonn and Jülich area, but the algorithms are planed to be adapted to the newly conceived DWD polarimetric C-Band 5 minute interval volume scan strategy. An extension of the 3D composite to all of Germany is therefore possible and set as a goal.

Diederich, Malte; Senf, Fabian; Wapler, Kathrin; Simmer, Clemens

2013-04-01

154

Mars weather and predictability: Modeling and ensemble data assimilation of spacecraft observations  

NASA Astrophysics Data System (ADS)

Combining the perspectives of spacecraft observations and the GFDL Mars General Circulation Model (MGCM) in the framework of ensemble data assimilation leads to an improved understanding of the weather and climate of Mars and its atmospheric predictability. The bred vector (BV) technique elucidates regions and seasons of instability in the MGCM, and a kinetic energy budget reveals their physical origins. Instabilities prominent in the late autumn through early spring seasons of each hemisphere along the polar temperature front result from baroclinic conversions from BV potential to BV kinetic energy, whereas barotropic conversions dominate along the westerly jets aloft. Low level tropics and the northern hemisphere summer are relatively stable. The bred vectors are linked to forecast ensemble spread in data assimilation and help explain the growth of forecast errors. Thermal Emission Spectrometer (TES) temperature profiles are assimilated into the MGCM using the Local Ensemble Transform Kalman Filter (LETKF) for a 30-sol evaluation period during the northern hemisphere autumn. Short term (0.25 sol) forecasts compared to independent observations show reduced error (3--4 K global RMSE) and bias compared to a free running model. Several enhanced techniques result in further performance gains. Spatially-varying adaptive inflation and varying the dust distribution among ensemble members improve estimates of analysis uncertainty through the ensemble spread, and empirical bias correction using time mean analysis increments help account for model biases. With bias correction, we estimate a predictability horizon of about 5 sols during which temperature, wind, and surface pressure forecasts initialized from an assimilation analysis are superior to a free running model forecast. LETKF analyses, when compared with the UK reanalysis, show a superior correspondence to independent radio science temperature profiles. Traveling waves in both hemispheres share a correspondence in phase, and temperature differences between the analyses are generally less than 5 K. Assimilation of Mars Climate Sounder (MCS) temperature profiles reveals the importance of vertical distributions of dust and water ice aerosol in reducing model bias. A strategy for assimilation of TES and MCS aerosol products is outlined for future work.

Greybush, Steven J.

155

Antarctic Weather  

NSDL National Science Digital Library

Visitors to this site can read a discussion about the weather in Anarctica, including why it is so cold, how weather observations are conducted there, and what role the continent plays in the global weather system. Links to related topics, a wind chill calculator, and a Fahrenheit-Celsius-Kelvin temperature converter are also provided.

156

Data Assimilation of SMAP Observations and the Impact on Weather Forecasts and Heat Stress  

NASA Technical Reports Server (NTRS)

SPoRT produces real-time LIS soil moisture products for situational awareness and local numerical weather prediction over CONUS, Mesoamerica, and East Africa ?Currently interact/collaborate with operational partners on evaluation of soil moisture products ?Drought/fire ?Extreme heat ?Convective initiation ?Flood and water borne diseases ?Initial efforts to assimilate L2 soil moisture observations from SMOS (as a precursor for SMAP) have been successful ?Active/passive blended product from SMAP will be assimilated similarly and higher spatial resolution should improve on local-scale processes

Zavodsky, Bradley; Case, Jonathan; Blankenship, Clay; Crosson, William; White, Khristopher

2014-01-01

157

On the dynamic estimation of relative weights for observation and forecast in numerical weather prediction  

NASA Technical Reports Server (NTRS)

The problem of merging direct and remotely sensed (indirect) data with forecast data to get an estimate of the present state of the atmosphere for the purpose of numerical weather prediction is examined. To carry out this merging optimally, it is necessary to provide an estimate of the relative weights to be given to the observations and forecast. It is possible to do this dynamically from the information to be merged, if the correlation structure of the errors from the various sources is sufficiently different. Some new statistical approaches to doing this are described, and conditions quantified in which such estimates are likely to be good.

Wahba, Grace; Deepak, A. (editor)

1988-01-01

158

Chalk Point Cooling Tower Project. Volume 3. Cooling Tower Drift Dye Tracer Experiment Surface Weather and Ambient Atmospheric Profile Data, June 16 and 17, 1977.  

National Technical Information Service (NTIS)

During the Chalk Point Cooling Tower Drift Dye Tracer Experiment meteorological data was taken at Chalk Point. This report is a compilation of that data and surface weather observations made at Andrew's Air Force Base and Patuxent Naval Air Station. The c...

1977-01-01

159

WORLD SURFACE CURRENTS FROM SHIP'S DRIFT OBSERVATIONS  

SciTech Connect

Over 4 million observations of ship's drift are on file at the U.S. National Oceanographic Data Centre, in Washington, D. C., representing a vast amount of information on ocean surface currents. The observed drift speeds are dependent on the frequency of occurence of the particular current speeds and the frequency of observation. By comparing frequency of observation with the drift speeds observed it is possible to confirm known current patterns and detect singularities in surface currents.

Duncan, C.P.; Schladow, S.G.

1980-11-01

160

An observed database to characterize the weather conditions associated with subtropical cyclogenesis over southern-southeastern Brazil  

NASA Astrophysics Data System (ADS)

A project to study the climatic, dynamic and synoptic aspects of subtropical cyclones that develop in southern-southeastern coast of Brazil is in development. The weather conditions associated with such cyclones is an important question that must be answered in this project. However, for such characterization it is necessary to use the local meteorological observations of wind, wind gust, rainfall, air temperature, etc. The NCEP (National Center for Environmental Prediction) reanalysis have spatial and time resolutions that provide elements to study the synoptic and dynamics of meteorological events (cyclone, anticyclones, troughs, ridges, monsoons circulations, etc) until the production of complex climatology. However, this analysis has coarse horizontal resolution (~250 Km) that often does not allow the identification of intense meteorological phenomena. A more precise characterization of location and intensity of weather conditions associated with subtropical cyclones would be performed using local observations. Therefore, this work describes the methodology to construct a database of surface weather observations using a relational database management system (RDBMS) MySQL. The data source are SYNOP (Surface Synoptic Observations), METAR (Meteorological Aerodrome Report), NCDC (National Climatic Data Center) and CETESB (Environmental Agency of Sao Paulo State) that are available online through dynamic web page. An iterative algorithm robot was developed to automate the data extraction. Most of the data source are encoded or at non-standard format, hence was developed an algorithm in C++, using the REGEX library, an engine of text pattern search, for decode and handle the exception (erroneous and corrupted data). After the data decoding and formatting it is stored into the MySQL database. The structure of database was divided into categories of tables: a table with the source of data definition, a table with stations information and two sets of tables (for hourly and daily data) for each variable (temperature, pressure, wind, rain, etc). The data in NCDC, SYNOP, METAR, and CETESB are available from 1942, 1999, 1997 and 1997, respectively. The work was extended to a data set that included the entire Latin America using the MySQL that give us a simple and versatile platform allowing the continued growth of the database. The next step is to establish a web interface to make the data available to general public.

Yamamoto, R.; Porfirio da Rocha, R.

2012-04-01

161

Spatial interpolation of atmospheric pressure observations from automatic weather stations in complex alpine terrain  

NASA Astrophysics Data System (ADS)

ARPA Lombardia is the environmental protection agency for the administrative region Lombardia and manages a high resolution meteorological network composed by hundreds of automatic weather stations. Among these, about one hundred are equipped with barometers. The historical barometric dataset is however affected by many large systematic errors. Thus, an effort is done to recover information from such observations. A bias estimation technique is applied, based on a statistical comparison with the pressure vertical profiles measured by the Milan Linate soundings. Furthermore, pressure observations undergo several quality checks to ensure coherence in the data entering the analysis procedure. The interpolation method is a model-independent implementation of Optimal Interpolation where background information is obtained by data detrending. A spatial consistency test based on the interpolation algorithm is performed to discard observations affected by occasional gross errors. The outputs of all quality tests are integrated in the ARPA Lombardia data quality control system.

Lussana, C.; Uboldi, F.; Salvati, M. R.; Ranci, M.

2010-09-01

162

Assessing the Impact of Observations on Numerical Weather Forecasts Using the Adjoint Method  

NASA Technical Reports Server (NTRS)

The adjoint of a data assimilation system provides a flexible and efficient tool for estimating observation impacts on short-range weather forecasts. The impacts of any or all observations can be estimated simultaneously based on a single execution of the adjoint system. The results can be easily aggregated according to data type, location, channel, etc., making this technique especially attractive for examining the impacts of new hyper-spectral satellite instruments and for conducting regular, even near-real time, monitoring of the entire observing system. This talk provides a general overview of the adjoint method, including the theoretical basis and practical implementation of the technique. Results are presented from the adjoint-based observation impact monitoring tool in NASA's GEOS-5 global atmospheric data assimilation and forecast system. When performed in conjunction with standard observing system experiments (OSEs), the adjoint results reveal both redundancies and dependencies between observing system impacts as observations are added or removed from the assimilation system. Understanding these dependencies may be important for optimizing the use of the current observational network and defining requirements for future observing systems

Gelaro, Ronald

2012-01-01

163

Optical effects of space weathering in lunar crustal magnetic anomaly regions based on CE-1 observations  

NASA Astrophysics Data System (ADS)

The discovery of mini-magnetospheres above the lunar surface suggests that magnetic shielding could have led to anomalous space weathering (little darkening with limited reddening) in magnetic anomaly regions. Using spectral data from Chang'E 1 Imaging Interferometer (IIM) and data from Lunar Prospector's magnetometer, we instigate the relationship between lunar crustal magnetic anomalies and the optical effects in those areas in association with space weathering. The IIM onboard China's Chang'E 1 (CE-1) spacecraft is a Fourier transform Sagnac imaging spectrometer operating in the visible to near infrared (0.48-0.96 ?m) spectral range, with 32 channels at spectral intervals of 325.5 cm-1. We selected four regions with crustal magnetic anomalies to study their albedo properties: three lunar swirls (Gerasimovich, Mare Marginis, and Reiner Gamma) and the area antipodal to Herzsprung. We found that all three of the anomalous albedo areas are associated with magnetic anomalies, however, no anomalous albedo feature is found in the last magnetic anomaly area. In addition, we also studied the correlation between magnetic anomaly strength and albedo anomaly on a global scale. Our initial analysis suggests an overall tread of less darkening with increased magnetic anomaly.

Li, H.; Wang, X.; Cui, J.; Fu, X.; Zhang, G.; Yao, M.; Liu, B.; Liu, J.; Li, C.; Ouyang, Z.

2013-12-01

164

New observational strategies for reconstructing the solar UV flux for space weather applications  

NASA Astrophysics Data System (ADS)

Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV range. However the continuous monitoring of the solar UV irradiance is a difficult task. Present Si photodetectors exhibit serious limitations in performance and lifetime. Moreover filters suffer from a rapid degradation which limit the duty cycle of the mission. Here we give a theoretical view of one kind of degradation based on the formation of pinholes on the optical surfaces. We propose a solution which is expected to overcome, at least partially, these problems. We propose a new approach based on the idea that it is not necessary to measure the all spectrum but that a few bands suffice to retrieve all the other wavelengths. Then we propose a new instrumental concept with detectors using only wide band gap materials. Those new detectors select directly the desired spectral range without using upstream filters which are the main source of measurement degradation. Five channels are at least needed to retrieve the full UV spectrum with an accuracy as good as the actual spectrometers for space weather applications. We strongly believe that this work could be an asset to the definition of future instruments in the framework of the Space situational Awareness raised by the European Space Agency.

Cessateur, Gaël.; Lilensten, Jean; Dudok De Wit, Thierry; Kretzschmar, Matthieu; BenMoussa, Ali

2012-07-01

165

Probing The Surface Properties Of Weathered Silicate Minerals To Better Understand Their Reactivity  

NASA Astrophysics Data System (ADS)

While we expect conventional reactive transport simulations to provide reliable estimations of the evolution of fluid-rock interactions over time scales of centuries and even more, recent experimental studies showed that they could hardly be satisfactorily used on simplified systems (e.g. batch experiments on single minerals), on time scales of weeks [1]. As emphasized elsewhere [1, 2], the reasons for such inconsistencies have to be sought in the nature of the rate laws used in the geochemical codes, which heavily rely on our description of the fundamental mechanisms involved during water-mineral reactions. In that respect, the present ongoing work aims at gathering some of our recent findings in the dissolution kinetics of a series of Al-free silicates, in relation to the physicochemical properties of their surfaces after/during hydrothermal weathering. A first still unresolved issue that we are addressing is the effect of ubiquitous silica-rich layers which form on silicate minerals. While µm-thick silica coatings formed on the surface of wollastonite crystals without significantly affecting their dissolution rate, we observed that nm-thick silica coatings fully passivate the surface of olivine crystals [1, 3]. We will show how the use of microscopic (STEM, HTEM) [3] and spectroscopic (ToF-SIMS, XPS) techniques helped us to unravel these paradoxical properties, and which chemical parameters could influence the textural features of the layers. A different (or supplementary) mechanism possibly responsible for unexpected decreases of silicate dissolution rate at “far-from-equilibrium” conditions (e.g. diopside, [4]) was proposed to arise from the surface topography of the dissolving crystals and the occurrence (or absence) of etch pits [5]. We will show how the in situ monitoring of the dissolving surface of diopside as a function of fluid saturation state in a HAFM flow-cell (e.g. [6]) is allowing us to address this question. [1] Daval et al (2010) Proceed WRI-13, 1, 713-716 [2] Zhu (2009) Rev Mineral Geochem, 70, 533-569 [3] Daval et al (2009) Am Mineral, 94, 1707-1726 [4] Daval el al (2010) Geochim Cosmochim Ac, 74, 2615-2633 [5] Arvidson & Luttge (2010) Chem Geol, 269, 79-88 [6] Saldi et al (2009) Geochim Cosmochim Ac, 73, 5646-5657

Daval, D.; Sissmann, O.; Saldi, G. D.; Hellmann, R.; Gin, S.; Corvisier, J.; Martinez, I.; Guyot, F. J.; Knauss, K. G.

2010-12-01

166

State of Art in space weather observational activities and data management in Europe  

Microsoft Academic Search

One of the primary scientific and technical goals of space weather is to produce data in order to investigate the Sun impact on the Earth and its environment. Studies based on data mining philosophy yield increase the knowledge of space weather physical properties, modelling capabilities and gain applications of various procedures in space weather monitoring and forecasting. Exchanging tailored individually

Iwona Stanislawska

2008-01-01

167

Climate-dependent sediment production: numerical modeling and field observations of variable grain size distributions from heterogeneous hillslope weathering of fractured basalt flows, Kohala Peninsula, Hawaii  

NASA Astrophysics Data System (ADS)

We present a numerical model for hillslope sediment production that includes climate-dependent chemical weathering rates and bedrock fracture spacings, and predicts how grain size distributions vary with climate and hillslope erosion rate. Understanding sediment preparation, or the in situ reduction of fractured bedrock to coarse sediment by heterogeneous weathering on hillslopes, is critical to understanding the evolution of mountainous landscapes, as sediment supply rates and size distributions can strongly influence river incision rates. The majority of soil production models assume a homogenous substrate and uniform weathering front, and therefore do not track the size of rock fragments and corestones, which become the sediment supplied to channels by hillslope erosion. Our model is inspired by the Kohala Peninsula on the big island of Hawaii, which has a gradient of mean annual precipitation (MAP) spanning over an order of magnitude that has been shown to influence the weathering rates of the basalt. Previous geochemical studies have constrained climate-dependent weathering rates for local soil production. Using these inputs, we developed a kinetics-based numerical model for the chemical weathering of initially fractured basalt into soil and coarse sediment over 150ky. Following first-order reaction kinetics, chemical weathering in the model decreases exponentially with both depth below the surface and time. The model starts with a column of repeating basalt flows (typically 1 m thick), each with fracture spacing distributions consistent with thermal-mechanical cooling characteristics. Each individual fracture-bound block is assumed to weather from the surface inwards, similar in form to a weathering rind. Since the model is constructed of discrete blocks, larger blocks remain as unweathered corestones (the "sediment"), surrounded by weathered material. In addition to a MAP-dependent initial surface weathering rate and rate constant, climate is also reflected in the length scale for the reduction in chemical weathering below the surface, or the flushing depth. The flushing depth is assumed to scale linearly with MAP, but decreases exponentially with increasing soil depth, as soil capillarity will imbibe infiltration. Modeling six MAP regimes between 500 and 3000 mm produces a non-linear increase in soil depths from 0.59 m soil to 5.15 m, which is broadly consistent with field observations from Kohala Peninsula. The median corestone grain size (D50) was calculated at model completion for the 20 blocks below the soil-rock interface. In the driest regime the D50 was 98% of that for the initial column, while the D50 for the wettest regime was 56% of the initial. This sediment preparation model predicts soil depths and tracks particle size reduction with variable climate-dependent weathering rates. Incorporating this type of model into sediment-transport dependent landscape evolution models may be the key to understanding the systematic differences in topography across spatially variable climate gradients, such as Kohala Peninsula.

Murphy, B. P.; Johnson, J. P.

2012-12-01

168

Evaluating the Impacts of NASA/SPoRT Daily Greenness Vegetation Fraction on Land Surface Model and Numerical Weather Forecasts  

NASA Technical Reports Server (NTRS)

The NASA Short-term Prediction Research and Transition (SPoRT) Center develops new products and techniques that can be used in operational meteorology. The majority of these products are derived from NASA polar-orbiting satellite imagery from the Earth Observing System (EOS) platforms. One such product is a Greenness Vegetation Fraction (GVF) dataset, which is produced from Moderate Resolution Imaging Spectroradiometer (MODIS) data aboard the NASA EOS Aqua and Terra satellites. NASA SPoRT began generating daily real-time GVF composites at 1-km resolution over the Continental United States (CONUS) on 1 June 2010. The purpose of this study is to compare the National Centers for Environmental Prediction (NCEP) climatology GVF product (currently used in operational weather models) to the SPoRT-MODIS GVF during June to October 2010. The NASA Land Information System (LIS) was employed to study the impacts of the new SPoRT-MODIS GVF dataset on land surface models apart from a full numerical weather prediction (NWP) model. For the 2010 warm season, the SPoRT GVF in the western portion of the CONUS was generally higher than the NCEP climatology. The eastern CONUS GVF had variations both above and below the climatology during the period of study. These variations in GVF led to direct impacts on the rates of heating and evaporation from the land surface. The second phase of the project is to examine the impacts of the SPoRT GVF dataset on NWP using the Weather Research and Forecasting (WRF) model. Two separate WRF model simulations were made for individual severe weather case days using the NCEP GVF (control) and SPoRT GVF (experimental), with all other model parameters remaining the same. Based on the sensitivity results in these case studies, regions with higher GVF in the SPoRT model runs had higher evapotranspiration and lower direct surface heating, which typically resulted in lower (higher) predicted 2-m temperatures (2-m dewpoint temperatures). The opposite was true for areas with lower GVF in the SPoRT model runs. These differences in the heating and evaporation rates produced subtle yet quantifiable differences in the simulated convective precipitation systems for the selected severe weather case examined.

Bell, Jordan R.; Case, Jonathan L.; Molthan, Andrew L.

2011-01-01

169

Observed change for the atmosphere and surface, and for extremes  

NASA Astrophysics Data System (ADS)

The evidence of climate change from observations of the atmosphere and surface has grown significantly during recent years. Advances in the global climate observing system (in particular using satellites and reanalyses) have contributed to improved monitoring capabilities. At the same time, new dataset developments since AR4 have improved understanding of data issues and observational uncertainties. Developing homogeneous long-term global and regional data records from different sources remains a challenge. Instrumental observations since about 1850 and satellite observations since 1979 indicate changes in atmospheric composition, radiation budgets, temperature, the hydrological cycle (including precipitation and clouds) and atmospheric circulation. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850. Confidence in precipitation change averaged over global land areas since 1901 is low prior to 1951 and medium afterwards. Changes in many extreme weather and climate events (such as cold spells, heat waves, heavy precipitation events, droughts and tropical cyclones) have been observed since about 1950, consistent with the warming. For some of these extremes, a revised global-scale assessment from previous IPCC reports is provided. Especially for extremes, assessments of recent observed changes are hampered by limited availability of long-term observations, changes in observing capabilities and practices over time, and methodological differences in the assessed studies.

Klein Tank, Albert M. G.; Rusticucci, Matilde; Hartmann, Dennis L.; Alexander, Lisa V.; Thorne, Peter W.

2014-05-01

170

Earth surface erosion and weathering from the 10Be (meteoric)/9Be ratio  

NASA Astrophysics Data System (ADS)

The isotope ratio of the meteoric cosmogenic nuclide 10Be to the mineral-derived stable isotope 9Be discloses both the Earth surface denudation rate and its weathering intensity. We develop a set of steady state mass balance equations that describes this system from a soil column over the hillslope scale to an entire river basin. The prerequisites making this new approach possible are: (1) the 9Be concentration of parent rock (typically 2.5±0.5 ppm in granitic and clastic sedimentary lithologies) is known; (2) both Be isotopes equilibrate between the fluids decomposing rock and reactive solids formed during weathering; and (3) a critical spatial scale is exceeded at which the fluxes of both isotopes into and out of the weathering zone are at steady state over the time scale of weathering (typically ˜10 kyr). For these cases the isotope ratios can be determined in bulk sediment or soil, on leachates from the reactive (adsorbed and pedogenic mineral-bound) phase in sediment or soil, and even on the dissolved phase in river water. The 10Be/9Be ratio offers substantial advantages over the single-isotope system of meteoric 10Be. The latter system allows to directly determine erosion rates only in the case that 10Be is fully retentive in the weathering zone and that riverine sorting has not introduced grain size-dependent 10Be concentration gradients in sediments. We show the feasibility of the 10Be/9Be tracer approach at the river scale for sediment and water samples in the Amazon basin, where independent estimates of denudation rates from in situ-produced 10Be exist. We furthermore calculate meaningful denudation rates from a set of published 10Be/9Be ratios measured in the dissolved load of globally distributed rivers. We conclude that this isotope ratio can be used to reconstruct global paleo-denudation from sedimentary records.

von Blanckenburg, Friedhelm; Bouchez, Julien; Wittmann, Hella

2012-10-01

171

A much warmer Earth surface for most of geologic time: implications to biotic weathering  

NASA Technical Reports Server (NTRS)

The authors present two scenarios for the temperature history of Earth. One scenario is conventional, the other relies on a warmer history. Both scenarios include surface cooling determined by the evolution of the biosphere and are similar until the Proterozoic period. The warmer scenario requires a higher plant/lichen terrestrial biota to increase weathering intensity. Justification for a warmer surface includes period temperatures from the oxygen isotope record of coexisting phosphates and cherts, an upper limit of 58 degrees C from primary gypsum precipitation, and the lack of fractionation of sulfur isotopes between sulfide and sulfates in Archean sediments.

Schwartzman, D. W.; McMenamin, M.

1993-01-01

172

Modeling COSMO-SkyMed measurements of precipitating clouds over the sea using simultaneous weather radar observations  

NASA Astrophysics Data System (ADS)

Several satellite missions employing X-band synthetic aperture radar (SAR) have been activated to provide high-resolution images of normalized radar cross-sections (NRCS) on land and ocean for numerous applications. Rainfall and wind affect the sea surface roughness and consequently the NRCS from the combined effects of corrugation due to impinging raindrops and surface wind. X-band frequencies are sensitive to precipitation: intense convective cells result in irregularly bright and dark patches in SAR images, masking changes in surface NRCS. Several works have modeled SAR images of intense precipitation over land; less adequately investigated is the precipitation effect over the sea surface. These images are analyzed in this study by modeling both the scattering and attenuation of radiation by hydrometeors in the rain cells and the NRCS surface changes using weather radar precipitation estimates as input. The reconstruction of X-band SAR returns in precipitating clouds is obtained by the joint utilization of volume reflectivity and attenuation, the latter estimated by coupling ground-based radar measurements and an electromagnetic model to predict the sea surface NRCS. Radar signatures of rain cells were investigated using X-band SAR images collected from the COSMO-SkyMed constellation of the Italian Space Agency. Two case studies were analyzed. The first occurred over the sea off the coast of Louisiana (USA) in summer 2010 with COSMO-SkyMed (CSK®) ScanSar mode monitoring of the Deepwater Horizon oil spill. Simultaneously, the NEXRAD S-band Doppler radar (KLIX) located in New Orleans was scanning the same portion of ocean. The second case study occurred in Liguria (Italy) on November 4, 2011, during an extraordinary flood event. The same events were observed by the Bric della Croce C-band dual polarization radar located close to Turin (Italy). The polarimetric capability of the ground radars utilized allows discrimination of the composition of the precipitation volume, in particular distinguishing ice from rain. Results shows that for space-borne SAR at X-band, effects due to precipitation on water surfaces can be modeled using coincident ground-based weather radar measurements.

Roberto, N.; Baldini, L.; Facheris, L.; Chandrasekar, V.

2014-07-01

173

Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects  

NASA Technical Reports Server (NTRS)

Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from <20 pm size factions (dry-sieved) of mature lunar soils. It has been demonstrated that it is the finest size fraction (<25 pm) of lunar soils that dominates the optical properties of the bulk soils.

Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

1998-01-01

174

Observation of Sea Breeze Front and its Induced Convection over Chennai in Southern Peninsular India Using Doppler Weather Radar  

Microsoft Academic Search

Sea breeze, the onshore wind over a coastal belt during daytime, is a welcoming weather phenomenon as it modulates the weather\\u000a condition by moderating the scorching temperature and acts as a favourable mechanism to trigger convection and induce precipitation\\u000a over coastal and interior locations. Sea breeze aids dispersal of pollutants as well. Observational studies about its onset,\\u000a depth of circulation

R. Suresh

2007-01-01

175

Observation of Sea Breeze Front and its Induced Convection over Chennai in Southern Peninsular India Using Doppler Weather Radar  

Microsoft Academic Search

Sea breeze, the onshore wind over a coastal belt during daytime, is a welcoming weather phenomenon as it modulates the weather\\u000a condition by moderating the scorching temperature and acts as a favourable mechanism to trigger convection and induce precipitation\\u000a over coastal and interior locations. Sea breeze aids dispersal of pollutants as well. Observational studies about its onset,\\u000a depth of circulation

R. Suresh

176

Combining Satellite Observations of Fire Activity and Numerical Weather Prediction to Improve the Prediction of Smoke Emissions  

NASA Astrophysics Data System (ADS)

Smoke emissions estimates used in air quality and visibility forecasting applications are currently limited by the information content of satellite fire observations, and the lack of a skillful short-term forecast of changes in fire activity. This study explores the potential benefits of a recently developed sub-pixel-based calculation of fire radiative power (FRPf) from the MODerate Resolution Imaging Spectroradiometer (MODIS), which provides more precise estimates of the radiant energy (over the retrieved fire area) that in turn, improves estimates of the thermal buoyancy of smoke plumes and may be helpful characterizing the meteorological effects on fire activity for large fire events. Results show that unlike the current FRP product, the incorporation of FRPf produces a statistically significant correlation (R = 0.42) with smoke plume height data provided by the Multi-angle Imaging SpectroRadiometer (MISR) and several meteorological variables, such as surface wind speed and temperature, which may be useful for discerning cases where smoke was injected above the boundary layer. Drawing from recent advances in numerical weather prediction (NWP), this study also examines the meteorological conditions characteristic of fire ignition, growth, decay, and extinction, which are used to develop an automated, 24-hour prediction of satellite fire activity. Satellite fire observations from MODIS and geostationary sensors show that the fire prediction model is an improvement (RMSE reduction of 13 - 20%) over the forecast of persistence commonly used by near-real-time fire emission inventories. The ultimate goal is to combine NWP data and satellite fire observations to improve both analysis and prediction of biomass-burning emissions, through improved understanding of the interactions between fire activity and weather at scales appropriate for operational modeling. This is a critical step toward producing a global fire prediction model and improving operational forecasts of smoke transport.

Peterson, D. A.; Wang, J.; Hyer, E. J.; Ichoku, C. M.

2012-12-01

177

Space Weathering Impact on Solar System Surfaces - Community White Paper for Planetary Science Decadal Survey 2009 - 2011  

Microsoft Academic Search

Universal processes of space weathering within and beyond the solar system include plasma ion implantation into surfaces, surface sputtering by plasma and energetic ions, surface volume ionization by penetrating charged particles, and radiolytic chemistry evolved from radiation products. Surface regolith layers on bodies with very thin or no significant atmospheres evolve structurally and chemically from impact processing by micrometeroids and

Kurt D. Retherford; J. F. Cooper; C. Paranicas; R. E. Johnson; E. C. Sittler; R. E. Hartle; M. A. McGrath; D. Pascu

2009-01-01

178

Iron weathering products in a CO 2 + (H 2O or H 2O 2) atmosphere: Implications for weathering processes on the surface of Mars  

NASA Astrophysics Data System (ADS)

Various iron-bearing primary phases and rocks have been weathered experimentally to simulate possible present and past weathering processes occurring on Mars. We used magnetite, monoclinic and hexagonal pyrrhotites, and metallic iron as it is suggested that meteoritic input to the martian surface may account for an important source of reduced iron. The phases were weathered in two different atmospheres: one composed of CO 2 + H 2O, to model the present and primary martian atmosphere, and a CO 2 + H 2O + H 2O 2 atmosphere to simulate the effect of strong oxidizing agents. Experiments were conducted at room temperature and a pressure of 0.75 atm. Magnetite is the only stable phase in the experiments and is thus likely to be released on the surface of Mars from primary rocks during weathering processes. Siderite, elemental sulfur, ferrous sulfates and ferric (oxy)hydroxides (goethite and lepidocrocite) are the main products in a water-bearing atmosphere, depending on the substrate. In the peroxide atmosphere, weathering products are dominated by ferric sulfates and goethite. A kinetic model was then developed for iron weathering in a water atmosphere, using the shrinking core model (SCM). This model includes competition between chemical reaction and diffusion of reactants through porous layers of secondary products. The results indicate that for short time scales, the mechanism is dominated by a chemical reaction with second order kinetics ( k = 7.75 × 10 -5 g -1/h), whereas for longer time scales, the mechanism is diffusion-controlled (De A = 2.71 × 10 -10 m 2/h). The results indicate that a primary CO 2- and H 2O-rich atmosphere should favour sulfur, ferrous phases such as siderite or Fe 2+-sulfates, associated with ferric (oxy)hydroxides (goethite and lepidocrocite). Further evolution to more oxidizing conditions may have forced these precursors to evolve into ferric sulfates and goethite/hematite.

Chevrier, V.; Mathé, P.-E.; Rochette, P.; Grauby, O.; Bourrié, G.; Trolard, F.

2006-08-01

179

Weather Information for Surface Transportation. A White Paper on Needs, Issues and Actions, Draft, May 15, 1998 (Revised).  

National Technical Information Service (NTIS)

The Federal Highway Administration (FHWA) Weather Team was formed in 1997 under the Intelligent Transportation System (ITS) program of the U.S. Department of Transportation (USDOT). This White Paper focuses on the needs of surface transportation decisions...

1998-01-01

180

Weather Information for Surface Transportation (WIST) Initiative Document: First Steps to Improve the Nation's WIST Capabilities and Services.  

National Technical Information Service (NTIS)

Since 1998, the Federal Committee for Meteorological Services and Supporting Research (FCMSSR) has made weather services and research and development (R&D) activities supporting the surface transportation community a priority for the Federal meteorologica...

2005-01-01

181

Automated Montana Hourly Weather Roundup.  

National Technical Information Service (NTIS)

This program automates the hourly weather roundup for Montana and a few selected cities outside the state as well. The Program uses the output file from the surface observation decoder program. The State Weather Roundup (SWR.SV) Program runs on the data g...

J. L. Johnston

1980-01-01

182

Satellite-observed sensitivity of weather condition for predicting malaria vector distribution in Bandarban district, Bangladesh  

NASA Astrophysics Data System (ADS)

A better understanding of the relationship between malaria epidemics, satellite data and the climatic anomalies could help mitigate the world-wide increase in incidence of the mosquitotransmitted diseases. This paper analyzes correlation between malaria cases and vegetation health (VH) Indices (Vegetation Condition Index (VCI) and Temperature Condition Index (TCI)) computed for each week over a period of 14 years (1992-2005). Following the results of correlation analysis the principal components regression (PCR) method was performed on weather components (TCI, VCI) of satellite data and climate variability during each of the two annual malaria seasons to construct a model to predict malaria as a function of the VH. A statistically significant relation was found between malaria cases and TCI during the month of June-July and September-October. Furthermore the simulated results found from PCR model were compared with observed malaria statistics showing that the error of the estimates of malaria is 5%.

Nizamuddin, Mohammad; Rahman, Atiqur; Roytman, Leonid; Kogan, Felix; Powell, Al; Goldberg, Mitch

2009-05-01

183

A twenty-first century California observing network for monitoring extreme weather events  

USGS Publications Warehouse

During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. In order to improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, is required. Here we describe how California is addressing their most important and costliest environmental issue – water management – in part, by installing a state-of-the-art observing system to better track the area’s most severe wintertime storms.

White, A. B.; Anderson, M. L.; Dettinger, M. D.; Ralph, F. M.; Hinojosa, A.; Cayan, D. R.; Hartman, R. K.; Reynolds, D. W.; Johnson, L. E.; Schneider, T. L.; Cifelli, R.; Toth, Z.; Gutman, S. I.; King, C. W.; Gehrke, F.; Johnston, P. E.; Walls, C.; Mann, D.; Gottas, D. J.; Coleman, T.

2013-01-01

184

Satellite maps of land roughness, albedo and surface temperature used in weather forecasting and climate modelling  

NASA Astrophysics Data System (ADS)

Surface boundary conditions for meteorological modelling for weather forecasting and climate scenarios are investigated in the current study. Focus is on interactions between air-land and air-sea. For the land surface, maps of roughness and albedo retrieved from satellite remote sensing images are tested in the HIRLAM model. HIRLAM is the operational weather forecast model in Denmark and six other European countries. The new roughness maps are calculated per season based on land cover type map from Landsat TM satellite images. Each land cover type is assigned a local roughness value (known from experiments and literature) and the effective roughness including the effect of hedges is calculated by use of an aggregation model. The main model characteristic is that the turbulent non-linear effect of the flow over rough and smooth patches is explicitly solved for in real terrain. Testing of the new roughness maps in the HIRLAM model show an improvement in the predicted wind speed pattern for Denmark. The test cases are from winter and spring. Testing of the new albedo maps based on NOAA AVHHR shows a slight change in predicted air temperature for weather forecasting when compared to predictions based on the operational albedo maps, however a greater effect would be found in a climate scenario in which the radiation balance has more importance. The sea surface temperature maps based on NOAA AVHHR and used in the HIRLAM model in place of climatic mean sea surface temperatures from ECMWF are tested for the same cases. The result shows the land-sea breeze to be better predicted with the satellite-based maps. The work was conducted in the SAT-MAP-CLIMATE project. Further information is available in Hasager et al. 2003 Boundary-Layer Met (accepted) and Hasager et al. 2002 http://www.risoe.dk/rispubl/VEA/ris-r-1350.htm

Hasager, C. B.; Nielsen, N. W.; Soegaard, H.; Boegh, E.; Christensen, J. H.; Dellwik, E.; Jensen, N. O.; Rasmussen, M. S.

2003-04-01

185

Modelling Glacier Surface Temperature Using Weather Station Data and Historical Climate Reconstructions  

NASA Astrophysics Data System (ADS)

Models of glacier response to climate change and snow/ice melt require knowledge of air temperatures at the glacier surface. This can be directly measured at selected locations, but distributed models of glacier melt require temperature information over an entire surface. Furthermore, in many practical applications, temperature must be estimated for locations where no data is available. A new and more accurate model to extrapolate temperature has been developed at the Haig Glacier in Alberta to meet this need. Air temperature measurements collected at an array of sites since 2001, including an expanded station network in the summer of 2008 to examine the effects of proximity to a south-facing valley wall, are used to create the model. Air temperatures 1.5 m above the surface of the Haig Glacier are then computed using the new model from data collected at a weather station located at the foot of the glacier. Temperature and precipitation data collected from this station is supplemented with digital elevation models and synoptic reanalysis data from the National Center for Environmental Prediction. The new temperature model accounts for differences in the effect of elevation, incoming solar radiation, albedo, regional weather systems, and valley walls on temperature between the weather station and a point on the glacier surface. This model yields hourly air temperature values across the glacier to a 25 m horizontal resolution. The new method of temperature extrapolation shows a considerable improvement over the constant lapse rate model in terms of accuracy and increased spatial variability. This model can be applied to simulations of summer melt and runoff from the Haig Glacier and from neighbouring ice masses, providing a tool for estimating catchment-scale melt water discharge and the sensitivity of glacier runoff to climate warming.

Schaffer, N.; Marshall, S. J.

2009-05-01

186

Modelling Glacier Surface Temperature Using Weather Station Data and Historical Climate Reconstructions  

NASA Astrophysics Data System (ADS)

Models of glacier response to climate change and snow/ice melt require knowledge of air temperatures at the glacier surface. This can be directly measured at selected locations, but distributed models of glacier melt require temperature information over an entire surface. Furthermore, in many practical applications, temperature must be estimated for locations where no data is available. A new and more accurate model to extrapolate temperature has been developed at the Haig Glacier in Alberta to meet this need. Air temperature measurements collected at an array of sites since 2001, including an expanded station network in the summer of 2008 to examine the effects of proximity to a south-facing valley wall, are used to create the model. Air temperatures 1.5 m above the surface of the Haig Glacier are then computed using the new model from data collected at a weather station located at the foot of the glacier. Temperature and precipitation data collected from this station is supplemented with digital elevation models and synoptic reanalysis data from the National Center for Environmental Prediction. The new temperature model accounts for differences in the effect of elevation, incoming solar radiation, albedo, regional weather systems, and valley walls on temperature between the weather station and a point on the glacier surface. This model yields hourly air temperature values across the glacier to a 25 m horizontal resolution. The new method of temperature extrapolation shows a considerable improvement over the constant lapse rate model in terms of accuracy and increased spatial variability. This model can be applied to simulations of summer melt and runoff from the Haig Glacier and from neighbouring ice masses, providing a tool for estimating catchment-scale melt water discharge and the sensitivity of glacier runoff to climate warming.

Schaffer, N.; Marshall, S. J.

2009-12-01

187

Biochemical evolution II: Origin of life in tubular microstructures on weathered feldspar surfaces  

PubMed Central

Mineral surfaces were important during the emergence of life on Earth because the assembly of the necessary complex biomolecules by random collisions in dilute aqueous solutions is implausible. Most silicate mineral surfaces are hydrophilic and organophobic and unsuitable for catalytic reactions, but some silica-rich surfaces of partly dealuminated feldspars and zeolites are organophilic and potentially catalytic. Weathered alkali feldspar crystals from granitic rocks at Shap, north west England, contain abundant tubular etch pits, typically 0.4–0.6 ?m wide, forming an orthogonal honeycomb network in a surface zone 50 ?m thick, with 2–3 × 106 intersections per mm2 of crystal surface. Surviving metamorphic rocks demonstrate that granites and acidic surface water were present on the Earth’s surface by ?3.8 Ga. By analogy with Shap granite, honeycombed feldspar has considerable potential as a natural catalytic surface for the start of biochemical evolution. Biomolecules should have become available by catalysis of amino acids, etc. The honeycomb would have provided access to various mineral inclusions in the feldspar, particularly apatite and oxides, which contain phosphorus and transition metals necessary for energetic life. The organized environment would have protected complex molecules from dispersion into dilute solutions, from hydrolysis, and from UV radiation. Sub-micrometer tubes in the honeycomb might have acted as rudimentary cell walls for proto-organisms, which ultimately evolved a lipid lid giving further shelter from the hostile outside environment. A lid would finally have become a complete cell wall permitting detachment and flotation in primordial “soup.” Etch features on weathered alkali feldspar from Shap match the shape of overlying soil bacteria.

Parsons, Ian; Lee, Martin R.; Smith, Joseph V.

1998-01-01

188

Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations  

NASA Technical Reports Server (NTRS)

The awareness of potentially significant impacts of space weather on spaceand ground ]based technological systems has generated a strong desire in many sectors of government and industry to effectively transform knowledge and understanding of the variable space environment into useful tools and applications for use by those entities responsible for systems that may be vulnerable to space weather impacts. Essentially, effectively transitioning science knowledge to useful applications relevant to space weather has become important. This talk will present proven methodologies that have been demonstrated to be effective, and how in the current environment those can be applied to space weather transition efforts.

Minow, Joseph I.; Pettit, Donald R.; Hartman, William A.

2012-01-01

189

Surface Material Analysis of the S-type Asteroids: Removing the Space Weathering Effect from Reflectance Spectrum  

NASA Technical Reports Server (NTRS)

Recent years, many researchers have been observing a lot of asteroid reflectance spectra in the UV, visible to NIR at wavelength region. Reflectance spectroscopy of asteroid at this range should bring us a lot of information about its surface materials. Pyroxene and olivine have characteristic absorption bands in this wavelength range. Low-Ca pyroxene has two absorption bands around 0.9 microns and 1.9 microns. The more Ca and Fe content, the longer both absorption band centers. On the other hand, reflectance spectrum of olivine has three complicated absorption bands around 1 m, and no absorption feature around 2 microns. In general, reflectance spectra of many asteroids that are considered to be silicate rich (i.e., S- and A type asteroids) show redder slope and more subdued absorption bands than those of terrestrial minerals and meteorites. These features are now believed to be caused by the space weathering effect, which is probably caused by micrometeorite bombardment and/or solar wind. This process causes nanophase reduced iron (npFe(sup 0)) particles near the surface of mineral grains, which leads the optical change. Therefore, the space weathering effect should be removed from asteroid reflectance spectra to compare with those of meteorite and terrestrial minerals. In this report, we will apply the expanded modified Gaussian model (MGM) to the reflectance spectra of S-type asteroids 7 Iris and 532 Herculina and compare them with those of meteorites.

Ueda, Y.; Miyamoto, M.; Mikouchi, T.; Hiroi, T.

2003-01-01

190

On the observation of surface magnetoplasmons  

Microsoft Academic Search

It is shown that, of the two techniques (grating or prism coupling) proposed for the observation of surface magnetoplasmons, the prism technique appears far superior. An analytic reflectivity formula is presented which will be necessary in the analysis of surface magnetoplasmon experimental data. Present address: Physics Department and Graduate Center for Materials Research, Univsity of Missouri-Rolla, Rolla, Missouri 65401, USA

Isreal L. Tyler; Bernhard Fischer; R. J. Bell

1973-01-01

191

The land surface-atmosphere interaction: A review based on observational and global modeling perspectives  

Microsoft Academic Search

This review discusses the land-surface-atmosphere interaction using observations from two North American field experiments (First International Satellite Land Surface Climatology Project Field Experiment (FIFE) and Boreal Ecosystem Atmosphere Study (BOREAS)) and the application of research data to the improvement of land surface and boundary layer parameterizations in the European Centre for Medium-Range Weather Forecast (ECMWF) global forecast model. Using field

Alan K. Betts; John H. Ball; Anton C. M. Beljaars; Martin J. Miller; Pedro A. Viterbo

1996-01-01

192

Micro-mapping Meteorite Surfaces on Mars using Microscopic Imager Mosaics — A Tool for Unraveling Weathering History at Meridiani Planum  

NASA Astrophysics Data System (ADS)

Meteorites found on Mars provide valuable insights into martian surface processes. During the course of Mars Exploration Rover (MER) extended missions, Spirit and Opportunity have identified 17 confirmed and candidate meteorites on Mars, most of which are irons. The iron meteorites exhibit morphologies and coatings that communicate complex post-fall exposure histories relevant to an understanding of climate near the martian equator [1-4]. Both chemical and mechanical weathering effects are represented. Among the more significant of these are: 1) cm-scale hollowing, 2) surficial rounding, 3) mass excavation/dissolution and removal, 4) differential etching of kamacite plates and taenite lamellae, revealing Widmanstätten patterns, 5) discontinuous iron oxide coatings, and 6) the effects of cavernous weathering, which often penetrate to rock interiors. Determining the nature, magnitude, and timing of each process and its associated features is a complex problem that will be aided by laboratory experiments, image processing, and careful surface evaluation. Because some features appear to superpose others in ways analogous to stratigraphic relationships, Microscopic Imager (MI) mosaics are useful for sketching "geologic maps" of meteorite surfaces. Employing the techniques of conventional planetary mapping [5], each map was drafted manually using full-resolution MI mosaics and Adobe Photoshop software. Units were selected to represent the oxide coating, dust-coated surfaces, sand-coated surfaces, taenite lamellae, and uncoated metal. Also included are areas in shadow, and regions of blooming caused by specular reflection of metal. Regmaglypt rim crests are presented as lineations. As with stratigraphic relationships, noting embayments and other cross-cutting relationships assists with establishing the relative timing for observed weathering effects. In addition to suggesting alternating sequences of wind and water exposure [1], patterns in oxide coating occurrence show evidence that coating deposition (interpreted as a result of water interaction) was geologically recent: Because the margins of many oxide coating deposits are concentric to and slightly removed from regmaglypt rim crests, the latest cycle is interpreted as a time of coating removal, not deposition, with these topographic high points representing zones of greatest erosional attack. Assuming the oxide coating has a low to moderate hardness, this observation implies relative geologic youth for the coating. However, it is unknown whether oxide deposits are stable or actively eroded by free basaltic sand grains [e.g., 6] in the modern epoch. The high science return from ongoing meteorite studies at MER landing sites supports their consideration if meteorites are also encountered by the Mars Science Laboratory Curiosity rover in Gale Crater.

Ashley, J. W.; Herkenhoff, K. E.; Golombek, M. P.; Johnson, J. R.

2012-12-01

193

Land Surface Model parameter regionalization with remote sensing and observations  

NASA Astrophysics Data System (ADS)

This study integrates modeling with observations in two ways. First, a land surface model (LSM) with a hydrologically-based soil moisture scheme is calibrated to observations across the continental U.S. for large river basins (on the order of USGS hydrologic regions and subregions) as well as for smaller tributary catchments. The observations include stream gauge records, as well as independent remote sensing estimates of evapotranspiration and terrestrial water storage change. This portion of the analysis serves to evaluate the extent to which remote sensing data can improve streamflow prediction and aid in the overall parameter estimation procedure. The second part of the study uses the calibrated model to derive a parameter regionalization framework using various observations as predictors. Predictors include land surface characteristics, geomorphic parameters and meteorological variables from several sources. Principal components analysis is used to establish predictive relationships between predictors and predictands. Predictands are the soil parameters of the Unified Land Model (ULM), which is a merger of the Noah LSM (used in NOAA/NCEP's numerical weather prediction and climate models) and the Sacramento Soil Moisture Accounting Model (used by NWS for operational flood forecasting and seasonal streamflow forecasting). Our major objective is to quantify the potential for the aforementioned predictands to produce model parameter sets that are capable of capturing observed patterns of streamflow, and which can be used as a priori parameter estimates over the CONUS domain. Finally, we evaluate the role of scale in model behavior and the observed physical phenomena.

Livneh, B.; Lettenmaier, D. P.

2011-12-01

194

Snow on the Ross Ice Shelf: comparison of reanalyses and observations from automatic weather stations  

NASA Astrophysics Data System (ADS)

Snow accumulation measurements from automatic weather stations (AWS) around the Ross Ice Shelf (RIS), Antarctica, are used to provide a new set of ground-based observations which are compared to precipitation from the ECMWF ERA-Interim and NCEP/NCAR Reanalysis-2 datasets. The high temporal resolution of the AWS snow accumulation measurements allow for an event-based comparison of reanalyses precipitation to the in situ observations. Snow accumulation records from nine AWS provide multiple years of accumulation data between 2008 and 2012 over a relatively large, homogeneous region of Antarctica, and also provide the basis for a statistical evaluation of accumulation and precipitation events. The complex effects of wind on snow accumulation (which can both limit and enhance accumulation) complicate the use of the accumulation measurements, but this analysis shows that they can provide a valuable source of ground-based observations for comparisons to modelled precipitation on synoptic timescales. The analysis shows that ERA-Interim reproduces more precipitation events than NCEP-2, and these events correspond to an average 8.2% more precipitation. Significant correlations between reanalyses and AWS event sizes are seen at several stations and show that ERA-Interim consistently produces larger precipitation events than NCEP-2.

Cohen, L.; Dean, S.

2013-09-01

195

Are weather models better than gridded observations for precipitation in the mountains? (Invited)  

NASA Astrophysics Data System (ADS)

Mountain snowpack is a critical storage component in the water cycle, and it provides drinking water for tens of millions of people in the Western US alone. This water store is susceptible to climate change both because warming temperatures are likely to lead to earlier melt and a temporal shift of the hydrograph, and because changing atmospheric conditions are likely to change the precipitation patterns that produce the snowpack. Current measurements of snowfall in complex terrain are limited in number due in part to the logistics of installing equipment in complex terrain. We show that this limitation leads to statistical artifacts in gridded observations of current climate including errors in precipitation season totals of a factor of two or more, increases in wet day fraction, and decreases in storm intensity. In contrast, a high-resolution numerical weather model (WRF) is able to reproduce observed precipitation patterns, leading to confidence in its predictions for areas without measurements and new observations support this. Running WRF for a future climate scenario shows substantial changes in the spatial patterns of precipitation in the mountains related to the physics of hydrometeor production and detrainment that are not captured by statistical downscaling products. The stationarity in statistical downscaling products is likely to lead to important errors in our estimation of future precipitation in complex terrain.

Gutmann, E. D.; Rasmussen, R.; Liu, C.; Ikeda, K.; Clark, M. P.; Brekke, L. D.; Arnold, J.; Raff, D. A.

2013-12-01

196

Monitoring ionospheric plasmas in space weather context via DSLP observations on board Proba-2  

NASA Astrophysics Data System (ADS)

The experiment Dual Segmented Langmuir Probe (DSLP) on board Proba-2 spacecraft (ESA) provides a long-term continual survey of basic plasma properties measured in situ in the dawn and dusk sectors of the upper terrestrial ionosphere. DSLP observations are acquired by two identical segmented spherical Langmuir probes representing a novel approach to a well developed plasma diagnostic technique. Starting its nominal operations in May 2010 almost four years of regular observations are currently being available providing a substantial data set for monitoring observed ionospheric disturbances and irregularities in view of potential space weather drivers. Here we present initial DSLP data scientific applications including seasonal or immediate variations of derived plasma properties in comparison with possible effects of sudden solar events or long term trends in the overall solar activity. In addition we present an on-line data archive build on complete DSLP data set where all raw measurements are routinely being processed into calibrated higher level data products derived from the PDS and CDF standards and made available throughout web interface.

Travnicek, Pavel; Stverak, Stepan; Hercik, David; Pavelka, Roman

2014-05-01

197

Observations, Simulations, and Modeling of Space Plasma Waves:. a Perspective on Space Weather  

Microsoft Academic Search

Changes in solar activity lead to adverse conditions within the upper atmosphere which may cause disruption of satellite operations, communications, navigation, and electric power grid. The term space weather is used to refer to changes in the Earth's space environment. This paper reviews plasma waves, found in all parts of the ionosphere and magnetosphere, in the context of space weather.

Vikas S. Sonwalkar

2007-01-01

198

Observation of Local Cloud and Moisture Feedbacks Associated with High Ocean and Desert Surface Temperatures  

NASA Technical Reports Server (NTRS)

New data on clouds and moisture, made possible by reanalysis of weather satellite observations, show that the atmosphere reacts to warm ocean pools in the Western Pacific Ocean with increased moisture and cloudiness, suggesting a negative feedback limiting the rise in sea-surface temperature.

Chahine, M. T.

1993-01-01

199

A Comparison of Surface Layer and Surface Turbulent Flux Observations over the Labrador Sea with ECMWF Analyses and NCEP Reanalyses  

Microsoft Academic Search

Comparisons are made between a time series of meteorological surface layer observational data taken on board the R\\/V Knorr, and model analysis data from the European Centre for Medium-Range Weather Forecasting (ECMWF) and the National Centers for Environmental Prediction (NCEP). The observational data were gathered during a winter cruise of the R\\/V Knorr, from 6 February to 13 March 1997,

Ian A. Renfrew; G. W. K. Moore; Peter S. Guest; Karl Bumke

2002-01-01

200

Assimilating QuikSCAT Ocean Surface Winds with the Weather Research and Forecasting Model for Surface Wind-Field Simulation over the Chukchi/Beaufort Seas  

NASA Astrophysics Data System (ADS)

To achieve a high-quality simulation of the surface wind field in the Chukchi/Beaufort Sea region, quick scatterometer (QuikSCAT) ocean surface winds were assimilated into the mesoscale Weather Research and Forecasting model by using its three-dimensional variational data assimilation system. The SeaWinds instrument on board the polar-orbiting QuikSCAT satellite is a specialized radar that measures ice-free ocean surface wind speed and direction at a horizontal resolution of 12.5 km. A total of eight assimilation case studies over two five-day periods, 1-5 October 2002 and 20-24 September 2004, were performed. The simulation results with and without the assimilation of QuikSCAT winds were then compared with QuikSCAT data available during the subsequent free-forecast period, coastal station observations, and North American Regional Reanalysis data. It was found that QuikSCAT winds are a potentially valuable resource for improving the simulation of ocean near-surface winds in the Chukchi/Beaufort Seas region. Specifically, the assimilation of QuikSCAT winds improved, (1) offshore surface winds as compared to unassimilated QuikSCAT winds, (2) sea-level pressure, planetary boundary-layer height, as well as surface heat fluxes, and (3) low-level wind fields and geopotential height. Verification against QuikSCAT data also demonstrated the temporal consistency and good quality of QuikSCAT observations.

Fan, Xingang; Krieger, Jeremy R.; Zhang, Jing; Zhang, Xiangdong

2013-07-01

201

Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition  

NASA Technical Reports Server (NTRS)

Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

Zhang, Shouliang; Keller, Lindsay P.

2011-01-01

202

Weather Forecasting  

NSDL National Science Digital Library

This activity (on page 2 of the PDF) is a full inquiry investigation into meteorology and forecasting. Learners will research weather folklore, specifically looking for old-fashioned ways of predicting the weather. Then, they'll record observations of these predictors along with readings from their own homemade barometer, graphing the correct predictions for analysis. Relates to linked video, DragonflyTV: Forecasting.

Twin Cities Public Television, Inc.

2005-01-01

203

Weather Instruments.  

ERIC Educational Resources Information Center

This booklet presents some activities to measure various weather phenomena. Directions for constructing a weather station are included. Instruments including rain gauges, thermometers, wind vanes, wind speed devices, humidity devices, barometers, atmospheric observations, a dustfall jar, sticky-tape can, detection of gases in the air, and pH of…

Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

204

Weather Instruments  

NSDL National Science Digital Library

This Topic in Depth discusses the variety of instruments used to collect climate and weather data. The first two websites provide simple introductions to the many weather instruments. Bethune Academy's Weather Center (1) discusses the functions of psychrometers, anemometers, weather balloons, thermometers, and barometers. The Illinois State Water Survey (2) furnishes many images of various instruments that collect data daily for legal issues, farmers, educators, students, and researchers. The third website (3), created by the Center for Improving Engineering and Science Education (CIESE), provides a classroom activity to educate users on how to build and use weather instruments. By the end of the group project, students should know all about wind vanes, rain gauges, anemometers, and thermometers. Next, the Miami Museum of Science provides a variety of activities to help students learn about the many weather instruments including wind scales and wind chimes (4). Students can learn about the wind, air pressure, moisture, and temperature. At the fifth website, the Tyson Research Center at Washington University describes the devices it uses in its research (5). At the various links, users can find out the center's many projects that utilize meteorological data such as acid rain monitoring. The sixth website, a pdf document created by Dr. John Guyton at the Mississippi State University Extension Service, provides guidance to teachers about the education of weather patterns and instruments (6). Users can find helpful information on pressure systems, humidity, cloud patterns, and much more. Next, the University of Richmond discusses the tools meteorologists use to learn about the weather (7). While providing materials about the basic tools discussed in the other websites, this site also offers information about weather satellites, radar, and computer models. After discovering the many weather instruments, users can learn about weather data output and analysis at the Next Generation Weather Lab website (8). This expansive website provides an abundance of surface data and upper air data as well as satellite and radar images for the United States.

205

Oscillation Responses to an Extreme Weather Event from a Deep Moored Observing System  

NASA Astrophysics Data System (ADS)

In June 2007 tropical Cyclone Gonu passed directly over an ocean observing system consisting of four, deep autonomous mooring stations along the 3000 m isobath in the northern Arabian Sea. Gonu was the largest cyclone known to have occurred in the Arabian Sea or to strike the Arabian Peninsula. The mooring system was designed by Lighthouse R & D Enterprises, Inc. and installed in cooperation with the Oman Ministry of Agriculture and Fisheries Wealth. The instruments on the moorings continuously recorded water velocities, temperature, conductivity, pressure, dissolved oxygen and turbidity at multiple depths and at hourly intervals during the storm. Near-inertial oscillations at all moorings from thermocline to seafloor are coincident with the arrival of Gonu. Sub-inertial oscillations with periods of 2-10 days are recorded at the post-storm relaxation stage of Gonu, primarily in the thermocline. These oscillations consist of warm, saline water masses, likely originating from the Persian Gulf. Prominent 12.7-day sub-inertial waves, measured at a station ~300 km offshore, are bottom-intensified and have characteristics of baroclinic, topographically-trapped waves. Theoretical results from a topographically-trapped wave model are in a good agreement with the observed 12.7-day waves. The wavelength of the 12.7-day waves is about 590 km calculated from the dispersion relationship. Further analysis suggests that a resonant standing wave is responsible for trapping the 12.7-day wave energy inside the Sea of Oman basin. The observational results reported here are the first measurements of deepwater responses to a tropical cyclone in the Sea of Oman/Arabian Sea. Our study demonstrates the utility of sustained monitoring for studying the impact of extreme weather events on the ocean.

Wang, Z.; Dimarco, S. F.; Stoessel, M. M.; Zhang, X.; Ingle, S.

2011-12-01

206

Impact Of Seawinds Scatterometer Data On Ocean Surface Analysis And Weather Prediction.  

National Technical Information Service (NTIS)

Scatterometer observations of the ocean surface wind speed and direction improve the depiction and prediction of storms at sea. These data are especially valuable where observations are otherwise sparse mostly in the Southern Hemisphere and tropics, but a...

E. Brin J. Ardizzone J. Terry R. Atlas S. C. Bloom

2003-01-01

207

Observations of Mesoscale and Microscale Space Weather Processes on the Canadian ASSIOPE Enhanced Polar Outflow Probe (e-POP)  

Microsoft Academic Search

CASSIOPE is a Canadian small satellite scheduled for launch in late 2007 into a polar orbit 300 times 1500 km 80 r inclination The scientific objective of its Enhanced Polar Outflow Probe e-POP payload is to make observations of mesoscale and microscale space weather processes in the topside polar ionosphere at the highest-possible resolution specifically to study the microscale characteristics

A. W. Yau; H. G. James

2006-01-01

208

Forecasting near-surface weather conditions and precipitation in Alaska's Prince William Sound with the PWS-WRF modeling system  

NASA Astrophysics Data System (ADS)

In the summer of 2009, several scientific teams engaged in a field program in Prince William Sound (PWS), Alaska to test an end-to-end atmosphere/ocean prediction system specially designed for this region. The "Sound Predictions Field Experiment" (FE) was a test of the PWS-Observing System (PWS-OS) and the culmination of a five-year program to develop an observational and prediction system for the Sound. This manuscript reports on results of an 18-day high-resolution atmospheric forecasting field project using the Weather Research and Forecasting (WRF) model.Special attention was paid to surface meteorological properties and precipitation. Upon reviewing the results of the real-time forecasts, modifications were incorporated in the PWS-WRF modeling system in an effort to improve objective forecast skill. Changes were both geometric (model grid structure) and physical (different physics parameterizations).The weather during the summer-time FE was typical of the PWS in that it was characterized by a number of minor disturbances rotating around an anchored low, but with no major storms in the Gulf of Alaska. The basic PWS-WRF modeling system as implemented operationally for the FE performed well, especially considering the extremely complex terrain comprising the greater PWS region.Modifications to the initial PWS-WRF modeling system showed improvement in predicting surface variables, especially where the ambient flow interacted strongly with the terrain. Prediction of precipitation on an accumulated basis was more accurate than prediction on a day-to-day basis. The 18-day period was too short to provide reliable assessment and intercomparison of the quantitative precipitation forecasting (QPF) skill of the PWS-WRF model variants.

Olsson, Peter Q.; Volz, Karl P.; Liu, Haibo

2013-07-01

209

Challenges of Representing Land-Surface Processes in Weather and Climate Models over the Tropics: Examples over the Indian Subcontinent  

Microsoft Academic Search

Land-surface processes are an important driver for weather and climate systems over the tropics and particularly the Indian subcontinent. Realistic representation of land- surface processes over the Indian region will help accurate simulations of environmen- tal processes at micro, meso, and regional climate scale. However, in order to achieve these potential benefits, it is necessary to develop a strategy through

DEV DUTTA S. NIYOGI; ROGER PIELKE SR; KIRAN ALAPATY; JOSEPH EASTMAN; TEDDY HOLT; U. C. MOHANTY; SETHU RAMAN; T. K. ROY; Y. K. XUE

210

Statistical relationship between surface PM10 concentration and aerosol optical depth over the Sahel as a function of weather type, using neural network methodology  

NASA Astrophysics Data System (ADS)

work aims at assessing the capability of passive remote-sensed measurements such as aerosol optical depth (AOD) to monitor the surface dust concentration during the dry season in the Sahel region (West Africa). We processed continuous measurements of AODs and surface concentrations for the period (2006-2010) in Banizoumbou (Niger) and Cinzana (Mali). In order to account for the influence of meteorological condition on the relationship between PM10 surface concentration and AOD, we decomposed the mesoscale meteorological fields surrounding the stations into five weather types having similar 3-dimensional atmospheric characteristics. This classification was obtained by a clustering method based on nonlinear artificial neural networks, the so-called self-organizing map. The weather types were identified by processing tridimensional fields of meridional and zonal winds and air temperature obtained from European Centre for Medium-Range Weather Forecasts (ECMWF) model output centered on each measurement station. Five similar weather types have been identified at the two stations. Three of them are associated with the Harmattan flux; the other two correspond to northward inflow of the monsoon flow at the beginning or the end of the dry season. An improved relationship has been found between the surface PM10 concentrations and the AOD by using a dedicated statistical relationship for each weather type. The performances of the statistical inversion computed on the test data sets show satisfactory skills for most of the classes, much better than a linear regression. This should permit the inversion of the mineral dust concentration from AODs derived from satellite observations over the Sahel.

Yahi, H.; Marticorena, B.; Thiria, S.; Chatenet, B.; Schmechtig, C.; Rajot, J. L.; Crepon, M.

2013-12-01

211

GEM: Statistical weather forecasting procedure  

NASA Technical Reports Server (NTRS)

The objective of the Generalized Exponential Markov (GEM) Program was to develop a weather forecast guidance system that would: predict between 0 to 6 hours all elements in the airways observations; respond instantly to the latest observed conditions of the surface weather; process these observations at local sites on minicomputing equipment; exceed the accuracy of current persistence predictions at the shortest prediction of one hour and beyond; exceed the accuracy of current forecast model output statistics inside eight hours; and be capable of making predictions at one location for all locations where weather information is available.

Miller, R. G.

1983-01-01

212

eHeroes and Swiff: EC-Funded FP7 networks for modelling and observation of space weather events  

NASA Astrophysics Data System (ADS)

We report on two EC-FP7 funded projects: Swiff and eHeroes. Swiff (swiff.eu) is a modelling effort that aims at producing an integrated space weather modelling and forecasting network. We are unifying into a single approach fluid and kinetic models to track space weather events from their solar origin to their impact on the Earth environment, eHeores (eheroes.eu) is a observational and modelling effort that collects and processes data to produce new data services and new models to track and predict space weather. eHeores focuses on the impact of space weather on space exploration including the effects on spacecraft, on the exploration of the Moon and Mars. We will report on the results obtained in these projects highlighting their relevance to space weather and its impact on the Earth and on space exploration. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SWIFF (project n° 263340, www.swiff.eu).

Lapenta, Giovanni

2013-04-01

213

Assimilation of observations with models to better understand severe ionospheric weather at mid-latitudes  

NASA Astrophysics Data System (ADS)

For many decades, the mid-latitude ionosphere was regarded as well characterized even if not well modeled. As a result, the Federal Aviation Authority's Wide Area Augmentation System (WAAS) was developed to provide augmented GPS positioning information to correct for ionospheric variability. However, over the past 5 years, recurrent superstorms in the ionosphere have forced the WAAS system to go offline for many hours at a time. This report discusses present-day knowledge regarding these conditions and how they are associated with unexpectedly steep horizontal gradients in the mid-latitude ionosphere total electron content (TEC). In a general sense, the possible physical mechanisms are understood, but during a storm the distribution and evolution of the driving forces for these mechanisms are neither understood nor adequately observed, the two main driving forces being the convection electric field and the neutral wind. In this paper a simplified convection electric field pattern is presented and used to drive a physics-based ionospheric model. This demonstrates how the superstorm ionospheric condition could be generated. Data assimilation is a new approach that could exceed present-day empirical and physical model limitations. There are three main expectations for data assimilation: (1) combined with a good ionospheric background model, the data assimilation must provide realistic global specification of the ionosphere; (2) it must also provide additional information about the ionosphere that is not already evident in the observation, that is, altitude profiles of the electron density when only slant TEC integrals of the electron density are available; and (3) with full physics-based models in the assimilation procedure, data assimilation models must also provide the drivers, that is, the neutral wind and electric field patterns. This paper examines the current status of these three expectations with regard to the future for the scientist and the space weather forecaster.

Sojka, Jan J.; Schunk, R. W.; Thompson, D. C.; Scherliess, L.; David, M.

214

The ELDORA/ASTRAIA Airborne Doppler Weather Radar: High-Resolution Observations from TOGA COARE.  

NASA Astrophysics Data System (ADS)

The ELDORA/ASTRAIA (Electra Doppler Radar/Analyese Stereoscopic par Impulsions Aeroporte) airborne Doppler weather radar was recently placed in service by the National Center for Atmospheric Research and the Centre d'étude des Environnements Terrestre et Planetaires in France. After a multiyear development effort, the radar saw its first field tests in the TOGA COARE (Tropical Oceans-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment) field program during January and February 1993. The ELDORA/ASTRAIA radar (herein referred to as ELDORA) is designed to provide high-resolution measurements of the air motion and rainfall characteristics of very large storms, storms that are frequently too large or too remote to be adequately observed by ground-based radars. This paper discusses the measurement requirements and the design goals of the radar and concludes with an evaluation of the performance of the system using data from TOGA COARE.The performance evaluation includes data from two cases. First, observations of a mesoscale convective system on 9 February 1993 are used to compare the data quality of the ELDORA radar with the National Oceanic and Atmospheric Administration P-3 airborne Doppler radars. The large-scale storm structure and airflow from ELDORA are seen to compare quite well with analyses using data from the P-3 radars. The major differences observed between the ELDORA and P-3 radar analyses were due to the higher resolution of the ELDORA data and due to the different domains observed by the individual radars, a result of the selection of flight track past the storm for each aircraft. In a second example, the high-resolution capabilities of ELDORA are evaluated using observations of a shear-parallel mesoscale convective system (MCS) that occurred on 18 February 1993. This MCS line was characterized by shear-parallel clusters of small convective cells, clusters that were moving quickly with the low-level winds. High-resolution analysis of these data provided a clear picture of the small scale of the storm vertical velocity structure associated with individual convective cells. The peak vertical velocities measured in the high-resolution analysis were also increased above low-resolution analysis values, in many areas by 50%-100%. This case exemplifies the need for high-resolution measurement and analysis of convective transport, even if the goal is to measure and parameterize the large-scale effects of storms. The paper concludes with a discussion of completion of the remaining ELDORA design goals and planned near-term upgrades to the system. These upgrades include an implementation of dual-pulse repetition frequency and development of real-time, in-flight dual-Doppler analysis capability.

Hildebrand, Peter H.; Lee, Wen-Chau; Walther, Craig A.; Frush, Charles; Randall, Mitchell; Loew, Eric; Neitzel, Richard; Parsons, Richard; Testud, Jacques; Baudin, François; Lecornec, Alain

1996-02-01

215

Sensitivity of free tropospheric carbon monoxide to atmospheric weather states and their persistency: an observational assessment over the Nordic countries  

NASA Astrophysics Data System (ADS)

Among various factors that influence the long-range transport of pollutants in the free troposphere (FT), the prevailing atmospheric weather states probably play the most important role in governing characteristics and efficacy of such transport. The weather states, such as a particular wind pattern, cyclonic or anticyclonic conditions etc, and their degree of persistency determine the spatio-temporal distribution and the final fate of the pollutants. This is especially true in the case of Nordic countries, where baroclinic disturbances and associated weather fronts primarily regulate local meteorology, in contrast to the lower latitudes where convective paradigm plays similar important role. Furthermore, the long-range transport of pollutants in the FT has significant contribution to the total column burden over the Nordic countries. However, there is insufficient knowledge on the large-scale co-variability of pollutants in the FT and atmospheric weather states based solely on observational data over this region. The present study attempts to quantify and understand this statistical co-variability while providing relevant meteorological background. To that end, we select eight weather states that predominantly occur over the Nordic countries and three periods of their persistency (3 days, 5 days, and 7 days), thus providing in total 24 cases to investigate sensitivity of free tropospheric carbon monoxide, an ideal tracer for studying pollutant transport, to these selected weather states. The eight states include four dominant wind directions (namely, NW, NE, SE and SW), cyclonic and anticyclonic conditions, and the enhanced positive and negative phases of the North Atlantic Oscillation (NAO). For our sensitivity analysis, we use recently released Version 6 retrievals of CO at 500 hPa from the Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite covering 11 yr period from September 2002 through August 2013 and winds from the ECMWF's ERA-Interim project to classify weather states for the same 11 yr period. We show that, among the various weather states studied here, southeasterly winds lead to highest observed CO anomalies (up to +8%) over the Nordic countries while transporting pollution from the central and eastern parts of Europe. The second (up to +4%) and third highest (up to +2.5%) CO anomalies are observed when winds are northwesterly (facilitating inter-continental transport from polluted North American regions) and during the enhanced positive phase of the NAO respectively. Higher than normal CO anomalies are observed during anticyclonic conditions (up to +1%) compared to cyclonic conditions. The cleanest conditions are observed when winds are northeasterly and during the enhanced negative phases of the NAO, when relatively clean Arctic air masses are transported over the Nordic regions in the both cases. In case of nearly all weather states, the CO anomalies consistently continue to increase or decrease as the degree of persistency of a weather state is increased. The results of this sensitivity study further provide an observational basis for the process-oriented evaluation of chemistry transport models, especially with regard to the representation of large-scale coupling of chemistry and local weather states and its role in the long-range transport of pollutants in such models.

Thomas, M. A.; Devasthale, A.

2014-04-01

216

Space Weather Measurements from the Surface of Mars with the RAD Instrument on the Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) is a compact, lightweight energetic particle analyzer currently operating on the surface of Mars as part of the Mars Science Laboratory (MSL) Mission. These are the first measurements of the radiation environment on the surface of another planet, and specifically Mars. RAD is providing synoptic measurements of GCR & SEP at a 2nd location in heliosphere (other than near-Earth or L1), and will aid heliospheric modeling over solar cycle. These observations of SEP fluxes will contribute to a SEP event database at Mars and Martian surface to aid prediction of Solar Energetic Particle (SEP) Events, including onset, temporal & size predictions. This presentation will provide an overview of the RAD investigation and present the early measurements of the radiation environment on the surface of Mars and discuss the importance of providing broad heliospheric coverage and situational awareness of space weather as we plan to send humans out into deep space and to Mars. RAD is supported by NASA (HEOMD) under JPL subcontract #1273039 to SwRI, and by DLR in Germany under contract with Christian-Albrechts-Universitat (CAU).

Hassler, D.; Zeitlin, C. J.; Wimmer-Schweingruber, R.; Mars Science Laboratory Science Team

2013-05-01

217

Observation and research for strong meteor shower and related catastrophic space weather  

NASA Astrophysics Data System (ADS)

During the first international joint observation for strong meteor shower, we made multi-subject observations for Leonids and Draconids and their disaster space weather events by several methods. Combining the synthetical analysis of Leonids, Perseids and Draconids and their related data from 1957 to 2003, we sufficiently confirm that the periodic strong meteor showers can result in the formation of catastrophic space weather events. The following summing-up is confirmed basically: 1.The formation mechanism of the strong meteor shower There are meteoroids with high density and uneven distribution close the cometary nucleus, especially in the direction of opposite the Sun and backside of the nucleus. They can stretch 1-11AU along the cometary orbit and 1-5 (&sim10^3AU) cross the orbit. Therefore good displays of meteor shower (10---100 times as usual) or storms (103---104 times as usual) can occur when the Earth passes a high density meteoroid stream during the period of 3 years before and 5 years after the perihelion passage of the comet. During that period, bolides or shooting stars which are serious harmful to spaceflight security increase greatly to 3%~10%. This corrects the wrong point of view that the harmful micro-meteoroids to spaceflight security in period meteor showers are <1 g only. 2. The cosmic dust maintaining mechanism of long-life Es layer in mid-latitude area It is proved the life of Es layer increased greatly when most ions are long-life metal type ions (Fe +, Mg + ?? ) which composite coefficient is much smaller than that of molecule type ions(O2 + , NO + ?? ). The observation for about 50 years roughly approves that the blanketing frequency of Es layer (fb Es) abnormally increase in large area (>105km2) and lasting long time (>15 min) only when strong meteor shower occurred at night. It is not f, l and c type Es layer evolved from sequence Es layer. This shows that the cause of fb Es increase is that the ionosphere was bombarded by an additional swarm of cometary dusts, much smaller than those which produce an ionization trail that can be detected by radio detectors. 3. Spaceflight security During the strong meteor shower, bolides or shooting stars which mass may >1 g increase obviously. Since its kinetic energy is great, a bolide will explode when impacting on spacecraft to produce compress waves passing to inner wall, therefore possibly result in break, except for bringing sunken marks on the outer wall. In a word, the possible damage of strong meteor showers to big spacecraft and long time staying spacecraft can not be neglect. Launch of spaceflight should be evaded and security step for spaceflight in orbit should be taken during the strong meteor shower.

Ma, Y. H.; He, Y. W.; Xu, P. X.; Zhao, H. B.

2007-07-01

218

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore is a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) is implementing the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for GOES data in support of an activity of the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to retrieve surface albedo by processing day-time, cloud-free geostationary observations from a single visible band. Currently, the GSA algorithm generates products operationally at EUMETSAT using geostationary data from satellites at 0° and 63°E and at JMA using 140°E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75°W) and GOES-W (135°W). For the GOES implementation, raw GOES observations are calibrated against AVHRR reflectance data available in PATMOS-x. Surface angular anisotropy is then determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process additionally requires ancillary total column ozone and water vapor values, which for the GOES implementation are acquired from the 20th Century Reanalysis V2 data set provided by the NOAA/OAR/ESRL PSD. The GSA algorithm produces a 10-day composite surface albedo map. This product will initially be developed for the period 2000-2003. Later, it will be applied to the complete GOES data collection (1978-present) as part of NOAA's Climate Data Record Program.

Matthews, J. L.; Lattanzio, A.; Hankins, B.; Inamdar, A.; Knapp, K.; Privette, J. L.

2011-12-01

219

Groundwater/surface-water interactions on deeply weathered surfaces of low relief: evidence from Lakes Victoria and Kyoga, Uganda  

NASA Astrophysics Data System (ADS)

Little is known of the interactions between groundwater and surface water on deeply weathered landscapes of low relief in the Great Lakes Region of Africa (GLRA). The role of groundwater in sustaining surface-water levels during periods of absent rainfall is disputed and groundwater is commonly excluded from estimations of surface-water balances. Triangulated piezometers installed beside lake gauging stations on Lake Victoria and Lake Kyoga in Uganda provide the first evidence of the dynamic interaction between groundwater and surface water in the GLRA. Stable isotope ratios (2H:1H, 18O:16O) support piezometric evidence that groundwater primarily discharges to lakes but show further that mixing of groundwater and lake water has occurred at one site on Lake Victoria (Jinja). Layered-aquifer heterogeneity, wherein fluvial-lacustrine sands overlie saprolite, gives rise to both rapid and slow groundwater fluxes to lakes which is evident from the recession of borehole hydrographs following recharge events. Darcy throughflow calculations suggest that direct contributions from groundwater to Lake Victoria comprise <1% of the total inflows to the lake. Groundwater/surface-water interactions are strongly influenced by changing drainage base (lake) levels that are controlled, in part, by regional climate variability and dam releases from Lake Victoria (Jinja).

Owor, Michael; Taylor, Richard; Mukwaya, Christine; Tindimugaya, Callist

2011-11-01

220

An Experimental Approach to Thermal and Solar Weathering of Mercury's Surface  

NASA Astrophysics Data System (ADS)

The surface of Mercury is heated to 450°C during the day and is periodically bombarded by the solar wind - processes that have likely been occurring for billions of years. Mercury’s ion tail is composed of ions including Na, K, and Ca and is thought to be the result of surface mineral damage from heat and irradiation processes, possibly including photon-stimulated desorption, thermal desorption, and impact vaporization. We are seeking to quantify the results of irradiation and thermal damage on likely surface minerals that make up the regolith by simulating space weathering. We irradiate anorthoclase, enstatite, diopside, and ilmenite with fast neutrons for 12hrs, and then heat these minerals to 1300°C. We also heat grains that have not been irradiated. The irradiation is equivalent to 40,000 Earth years on the surface of Mercury. The grains are analyzed in an electron microprobe before and after irradiation and/or heating. Our initial results take the form of compositional profiles from the interior to the exterior of grains, showing ion losses from both irradiation and heating; we compare our curves with those from diffusion models. The results of these studies should indicate the species and volumes of ions likely to be released from each mineral, and should pave the way for measuring spectra of damaged minerals in labs, with the goal of comparing the spectra of damaged minerals with spectra obtained from MESSENGER.

Brown, S. M.; Elkins-Tanton, L. T.

2010-12-01

221

Earth surface erosion and weathering from the 10Be (meteoric)/9Be ratio  

NASA Astrophysics Data System (ADS)

A perfect clock of the stability of the Earth surface is one that combines a first isotope the flux of which depends on the release rate during erosion, and a second isotope produced at constant rate. The ratio of the meteoric cosmogenic nuclide 10Be to stable 9Be is such a system. We provide a quantitative framework for its use. In a weathering zone some of the 9Be, present typically in 2.5ppm concentrations in silicate minerals, is released and partitioned between a reactive phase (adsorbed to clay and hydroxide surfaces, given the high partition coefficients at intermediate pH), and into the dissolved phase. The combined mass flux of both phases is defined by the soil formation rate and a mineral dissolution rate - and is hence proportional to the chemical weathering rate and the denudation rate. At the same time, the surface of the weathering zone is continuously exposed to fallout of meteoric 10Be. This 10Be percolates into the weathering zone where it mixes with dissolved 9Be. Both isotopes may exchange with the adsorbed Be, given that equilibration rate of Be is fast relative to soil residence times. Hence a 10Be/9Be(reactive) ratio results in soils from which the total denudation rate can be calculated. A prerequisite is that the flux of meteoric 10Be is known from field experiments or from global production models [1], that the 9Be concentration in bedrock (mostly 2.5ppm) is known [2], and that the reactive Be can be chemically extracted from soil or sediment [3]. In rivers, when reactive Be and dissolved Be equilibrate, a catchment-wide denudation rate can be determined from both sediment and a sample of filtered river water, where the sediment 10Be/9Be ratio is independent of grain size. We have tested this approach in sediment-bound Be and dissolved Be in water of the Amazon and Orinoco basin. The reactive Be was extracted from sediment by combined hydroxylamine and HCl leaches [2]. In the Amazon trunk stream, the Orinoco, Apure, and La Tigra river 10Be/9Be(dissolved) agrees well with 10Be/9Be(reactive), showing that in most rivers these two phases equilibrate. 10Be/9Be ratios range from 5E-9 for the Brazilian shield rivers to 2E-10 for the Beni river draining the Andes, corresponding to denudation rates of 0.01mm/yr for the shields and 0.5mm/yr for the Andes, compatible with denudation rates from in situ-produced cosmogenic 10Be. Once delivered to the ocean, this riverine Be, be it dissolved or reactive, will eventually drive 10Be/9Be ratios of ocean water and disclose global denudation rates - at the present and in the sedimentary record from the past. [1] Willenbring and von Blanckenburg, Earth Sc. Reviews 98, 2010 [2] von Blanckenburg et al., Earth Planet. Sc. Lett. in press, 2012 [3] Wittmann et al., Chem Geol., 318-319, 2012

von Blanckenburg, F.; Bouchez, J.; Wittmann, H.; Dannhaus, N.

2012-12-01

222

The rate of chemical weathering of pyrite on the surface of Venus  

NASA Astrophysics Data System (ADS)

This abstract reports results of an experimental study of the chemical weathering of pyrite (FeS2) under Venus-like conditions. This work, which extends the earlier study by Fegley and Treiman, is part of a long range research program to experimentally measure the rates of thermochemical gas-solid reactions important in the atmospheric-lithospheric sulfur cycle on Venus. The objectives of this research are (1) to measure the kinetics of thermochemical gas-solid reactions responsible for both the production (e.g., anhydrite formation) and destruction (e.g., pyrrhotite oxidation) of sulfur-bearing minerals on the surface of Venus and (2) to incorporate these and other constraints into holistic models of the chemical interactions between the atmosphere and surface of Venus. Experiments were done with single crystal cubes of natural pyrite (Navajun, Logrono, Spain) that were cut and polished into slices of known weight and surface area. The slices were isothermally heated at atmospheric pressure in 99.99 percent CO2 (Coleman Instrument Grade) at either 412 C (685 K) or 465 C (738 K) for time periods up to 10 days. These two isotherms correspond to temperatures at about 6 km and 0 km altitude, respectively, on Venus. The reaction rate was determined by measuring the weight loss of the reacted slices after removal from the furnace. The reaction products were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy on the SEM.

Fegley, B., Jr.; Lodders, K.

1993-03-01

223

The rate of chemical weathering of pyrite on the surface of Venus  

NASA Technical Reports Server (NTRS)

This abstract reports results of an experimental study of the chemical weathering of pyrite (FeS2) under Venus-like conditions. This work, which extends the earlier study by Fegley and Treiman, is part of a long range research program to experimentally measure the rates of thermochemical gas-solid reactions important in the atmospheric-lithospheric sulfur cycle on Venus. The objectives of this research are (1) to measure the kinetics of thermochemical gas-solid reactions responsible for both the production (e.g., anhydrite formation) and destruction (e.g., pyrrhotite oxidation) of sulfur-bearing minerals on the surface of Venus and (2) to incorporate these and other constraints into holistic models of the chemical interactions between the atmosphere and surface of Venus. Experiments were done with single crystal cubes of natural pyrite (Navajun, Logrono, Spain) that were cut and polished into slices of known weight and surface area. The slices were isothermally heated at atmospheric pressure in 99.99 percent CO2 (Coleman Instrument Grade) at either 412 C (685 K) or 465 C (738 K) for time periods up to 10 days. These two isotherms correspond to temperatures at about 6 km and 0 km altitude, respectively, on Venus. The reaction rate was determined by measuring the weight loss of the reacted slices after removal from the furnace. The reaction products were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy on the SEM.

Fegley, B., Jr.; Lodders, K.

1993-01-01

224

Sublimation on the Greenland Ice Sheet from automated weather station observations  

NASA Astrophysics Data System (ADS)

Greenland Climate Network (GC-Net) surface meteorological observations are used to estimate net surface water vapor flux at ice sheet sites. Results from aerodynamic profile methods are compared with eddy correlation and evaporation pan measurements. Two profile method types are applied to hourly data sets spanning 1995.4 to 2000.4. One method type is shown to accurately gauge sublimation using two humidity and wind speed measurement levels. The other "bulk" method type is shown to underestimate condensation, as it assumes surface saturation. General climate models employ bulk methods and, consequently, underestimate deposition. Loss of water vapor by the surface predominates in summer at lower elevations, where bulk methods agree better with two-level methods. Annual net water vapor flux from the two-level method is as great as -87±27 mm at 960 m elevation and -74±23 mm at equilibrium line altitude in western Greenland. At an undulation trough site, net deposition is observed (+40 mm ±12). At the adjacent crest site 6 km away and at 50 m higher elevation, net sublimation predominates. At high-elevation sites, the annual water vapor flux is positive, up to +32±9 mm at the North Greenland Ice core Project (NGRIP) and +6±2 mm at Summit. Sublimation is mapped using trend surface fits to calculated sublimation in terms of elevation and latitude. The resulting ice sheet total sublimation is -0.62 ± 0.25 × 1014 kg yr-1 for the two-level profile method and -1.2 ± 0.65 × 1014 kg yr-1 for the one-level method, indicating 12% or 23% precipitation loss, respectively. Monthly, seasonal, and annual sublimation grids and the mapping functions are available on the internet at http://cires.colorado.edu/steffen.

Box, Jason E.; Steffen, Konrad

2001-12-01

225

Surface Temperature Observations from AVHRR in FIFE.  

NASA Astrophysics Data System (ADS)

Observations of the surface radiometric temperature by the AVHRR sensor on board the NOAA-9 satellite during the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment conducted in central Kansas during 1987 are presented. The satellite observations were corrected for atmospheric effects using a path radiance model (MODTRAN3) and radiosonde measurements. Problems with this approach include the nonsimultaneity of the soundings with the overpass and errors involved in profile measurements. For the former, soundings before and after the overpass were interpolated to the time of the overpass. For the latter, some of the errors arise from the ±0.5°C uncertainty in the dry- and wet-bulb temperatures, which can produce up to a ±14% relative uncertainty in the water vapor. To overcome this uncertainty, the water vapor profiles were adjusted until the channel 4 and 5 temperature differences over a large reservoir were reduced to zero. This adjusted profile was then used over the entire site. The results are compared to ground broadband temperature readings at 10 sites and to aircraft results from the thermal channel of the NS001 sensor on the C-130 aircraft. The AVHRR values were found to be 5° to 6°C warmer than the average of the ground measurements. This difference is attributed to the fact that the ground measurements were made preferentially on well-vegetated surfaces while the AVHRR integrates over the entire site, which includes many warm surfaces.

Schmugge, T. J.; Schmidt, G. M.

1998-04-01

226

Observing Global Surface Water Flood Dynamics  

NASA Astrophysics Data System (ADS)

Flood waves moving along river systems are both a key determinant of globally important biogeochemical and ecological processes and, at particular times and particular places, a major environmental hazard. In developed countries, sophisticated observing networks and ancillary data, such as channel bathymetry and floodplain terrain, exist with which to understand and model floods. However, at global scales, satellite data currently provide the only means of undertaking such studies. At present, there is no satellite mission dedicated to observing surface water dynamics and, therefore, surface water scientists make use of a range of sensors developed for other purposes that are distinctly sub-optimal for the task in hand. Nevertheless, by careful combination of the data available from topographic mapping, oceanographic, cryospheric and geodetic satellites, progress in understanding some of the world's major river, floodplain and wetland systems can be made. This paper reviews the surface water data sets available to hydrologists on a global scale and the recent progress made in the field. Further, the paper looks forward to the proposed NASA/CNES Surface Water Ocean Topography satellite mission that may for the first time provide an instrument that meets the needs of the hydrology community.

Bates, Paul D.; Neal, Jefferey C.; Alsdorf, Douglas; Schumann, Guy J.-P.

2014-05-01

227

Observation of local cloud and moisture feedbacks over high ocean and desert surface temperatures  

NASA Technical Reports Server (NTRS)

New data on clouds and moisture, made possible by reanalysis of weather satellite observations, show that the atmosphere reacts to warm clusters of very high sea surface temperatures in the western Pacific Ocean with increased moisture, cloudiness, and convection, suggesting a negative feedback limiting the sea surface temperature rise. The reverse was observed over dry and hot deserts where both moisture and cloudiness decrease, suggesting a positive feedback perpetuating existing desert conditions. In addition, the observations show a common critical surface temperature for both oceans and land; the distribution of atmospheric moisture is observed to reach a maximum value when the daily surface temperatures approach 304 +/- 1 K. These observations reveal complex dynamic-radiative interactions where multiple processes act simultaneously at the surface as well as in the atmosphere to regulate the feedback processes.

Chahine, Moustafa T.

1995-01-01

228

WeatherNet  

NSDL National Science Digital Library

WeatherNet, brought to us by The Weather Underground at University of Michigan, aims to be the premier site of weather links on the Internet. Besides the topical tropical storm page, you can view Accu-Weathers graphics including Nexrad imagery, satellite photos, surface maps, and forecast maps.

1998-01-01

229

The Atmospheric Imaging Radar (AIR) for high-resolution observations of severe weather  

Microsoft Academic Search

Rapid updates are a highly desired feature in the field of mobile weather radars. Various techniques have been used to improve volume update times, including the use of agile and multi-beam radars. Imaging radars, similar in some respects to phased arrays, steer the radar beam in software, thus requiring no physical motion. In contrast to phased arrays, imaging radars gather

Brad Isom; Robert Palmer; Redmond Kelley; John Meier; David Bodine; Mark Yeary; Boon Leng Cheong; Yan Zhang; Tian-You Yu; Mike Biggerstaff

2011-01-01

230

Assimilation of global ASCAT soil moisture observations in the ECMWF Numerical Weather Prediction Model  

Microsoft Academic Search

The European Centre for Medium-Range Weather Forecasts (ECMWF) currently prepares for the assimilation of soil moisture data derived from advanced scatterometer (ASCAT) measurements and from the Soil Moisture and Ocean Salinity Mission (SMOS). Here we will report on first results from the assimilation of ASCAT data into the Integrated Forecasting System of the ECMWF. ASCAT is part of the MetOp

K. Scipal; M. Drusch; G. Balsamo; P. de Rosnay

2009-01-01

231

Observations of space weather events from the Sun to the Earth ionosphere and thermosphere  

Microsoft Academic Search

Solar events and their impact on the terrestrial environment have received a lot of attention in recent years Nevertheless the relations between the solar source and their effects in the terrestrial environment are far from being understood quantitatively let it be for the physical mechanisms solar-terrestrial physics or for the effects on living bodies and technological systems space weather Are

C. Hanuise

2006-01-01

232

Doppler shift observations of severe tropospheric weather effects in the ionosphere  

Microsoft Academic Search

Tropospheric severe weather events are regarded as an important natural source of infrasound. They influence the ionosphere through the upward propagating waves. Due to temperature profile in the lower atmosphere, the infrasonic waves are focused upwards and most of the radiated energy can propagate to the upper atmosphere. Detection of infrasonic waves requires sampling in short intervals or preferably continuous

T. Sindelarova; D. Buresova; J. Lastovicka; J. Chum

2007-01-01

233

The surface of Mercury from ground-based astronomical observations  

NASA Astrophysics Data System (ADS)

Recent ground-based astronomical short-exposure observations of Mercury have yielded more than 50000 electronic pictures of the planet at different phases and different positions relative to the Earth. The work was fulfilled in several observatories. The use of available and newly developed processing methods applied to large volumes of electronic frames allowed the images of a considerable portion of Mercury’s surface to be synthesized. We present the images of the 90° 180°W, 215° 280°W, and 50° 90°W sectors containing, among others, the longitudes not covered by spacecraft imaging. Along with the listed images, we present the results of recent observations of Mercury carried out on November 20 24, 2006 during the morning elongation at the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) (Nizhnii Arkhyz, Karachai-Circassia, the Caucasus). The 265° 350°W longitude sector of Mercury was observed. The observations were made under good weather conditions. Among the main tasks of the new observations was obtaining a complete view of the S Basin. Previously, this basin had been investigated in fragments only by the actual solar illumination conditions. During the period of November 20 24, 2006, the S Basin was on the sunlit side of the planet. The complete image of the basin was obtained from the processing of a large number of electronic frames. The appearance of the S Basin is compared with the data on its relief acquired with radar methods. In this longitude sector, a number of other unusual surface features were found; among them, are a huge “Medallion” crater and other formations. The results considered in the present and earlier published studies are compared with the Mariner 10 data (1974 1975) and with the data received from the Messenger spacecraft during its first flyby of the planet (January 2008).

Ksanfomality, L. V.

2008-12-01

234

Characterization of space weathering from Lunar Reconnaissance Orbiter Camera ultraviolet observations of the Moon  

NASA Astrophysics Data System (ADS)

investigate the effects of space weathering at ultraviolet wavelengths using a near-global seven-band (321-689 nm) mosaic from the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC). We confirm that for moderate- to high-iron compositions (? 5 wt % FeO), the steeply positive UV slope at wavelengths <415 nm shallows with increasing exposure to space weathering. We measure these differences in LROC WAC data as variations in the 321/415 nm ratio, which has low values for fresh craters in the mare and moderate-iron highlands. For low-iron highland compositions, the break in slope occurs at shorter wavelengths, and it is instead the 321/360 nm ratio that increases with exposure to the space-weathering environment, whereas the 321/415 nm ratio appears to be largely controlled by the degree of shock experienced during the impact. The effects of shock may be more important at highland craters because modest shock pressures result in the solid-state transformation of plagioclase to its glass equivalent, maskelynite, and can help distinguish between primary shocked ejecta and locally exposed fresh material in rays. While all of the "fresh" craters we examined have UV spectral properties consistent with substantial alteration due to space weathering, the UV spectra of lunar swirls (magnetically shielded from the solar wind) are consistent with exposure of immature, crystalline material. Together these results suggest that lunar space weathering is dominated by the solar wind and "saturates" in the UV at Is/FeO values of ~40 (submature).

Denevi, Brett W.; Robinson, Mark S.; Boyd, Aaron K.; Sato, Hiroyuki; Hapke, Bruce W.; Hawke, B. Ray

2014-05-01

235

Global surface-based cloud observation for ISCCP  

NASA Technical Reports Server (NTRS)

Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a few regions; they are generally in better agreement if the moonlight criterion is imposed on the surface observations. Using the moonlight criterion, we have analyzed ten years (1982-1991) of surface weather observations over land and ocean, worldwide, for total cloud cover and for the frequency of occurrence of clear sky, fog and precipitation The global average cloud cover (average of day and night) is about 2% higher if we impose the moonlight criterion than if we use all observations. The difference is greater in winter than in summer, because of the fewer hours of darkness in the summer. The amplitude of the annual cycle of total cloud cover over the Arctic Ocean and at the South Pole is diminished by a few percent when the moonlight criterion is imposed. The average cloud cover for 1982-1991 is found to be 55% for northern hemisphere land, 53% for southern hemisphere land, 66% for northern hemisphere ocean, and 70% for southern hemisphere ocean, giving a global average of 64%. The global average for daytime is 64.6% for nighttime 63.3%.

1994-01-01

236

Observation of Sea Breeze Front and its Induced Convection over Chennai in Southern Peninsular India Using Doppler Weather Radar  

NASA Astrophysics Data System (ADS)

Sea breeze, the onshore wind over a coastal belt during daytime, is a welcoming weather phenomenon as it modulates the weather condition by moderating the scorching temperature and acts as a favourable mechanism to trigger convection and induce precipitation over coastal and interior locations. Sea breeze aids dispersal of pollutants as well. Observational studies about its onset, depth of circulation and induced precipitation have been carried out in this paper for the period April to September, 2004 2005 using a S-band Doppler Weather Radar functioning at Cyclone Detection Radar Station, India Meteorological Department, Chennai, India. The onset of sea breeze has been observed to be between 0900 and 1000 UTC with the earliest onset at 0508 UTC and late onset at 1138 UTC. The frequency is greater during the southwest monsoon season, viz., June September and the frequency of initial onset is greater in north Chennai. The modal length of sea breeze is between 20 and 50 km with extreme length as high as 100 km also having been observed. Though the inland penetration is on average 10 to 20 km, penetration reaching 100 km was also observed on a number of cases. The induced convection could be seen in the range 50 100 km in more than 53% of the cases. The mean depth of sea breeze circulation is 300 600 m but may go well beyond 1000 m on conducive atmospheric conditions.

Suresh, R.

2007-09-01

237

Architecture vision and technologies for post-NPOESS weather prediction system: two-way interactive observing and modeling: Part II. Use case scenario  

NASA Astrophysics Data System (ADS)

This is a companion paper to "Architecture Vision and Technologies for post-NPOESS Weather Prediction System: Two-way Interactive Observing and Modeling". Our recently completed two-year NASA-sponsored study on Advanced Weather Forecasting Technologies concluded that it may be possible in the future to significantly extend the skill range of model based weather forecasting via a direct real-time two-way feedback between computer forecast models and highly networked, intelligent observing systems (Sensor Webs). The study group developed a high-level Weather Architecture to describe the system (see the companion paper). This paper describes application of the proposed Weather Architecture to a particular weather scenario-the US east coast Blizzard of January 24 and 25, 2000. The objective of the scenario exercise was to help clarify thinking on the architecture functions in light of realistic, tractable (1 to 5 day) forecast situations, and infrastructure and technologies that might be reasonably projected for 2015.

Higgins, Glenn J.; Kalb, Michael W.; Mahoney, Robert L.; Lutz, Robert; Mauk, Robin Y.; Seablom, Michael; Talabac, Stephen J.

2005-01-01

238

Impact of synoptic weather patterns on spatio-temporal variation in surface O3 levels in Hong Kong during 1999-2011  

NASA Astrophysics Data System (ADS)

Potential impacts of circulation patterns on surface ozone (O3) concentrations over Hong Kong were investigated for the time period of 1999-2011. Synoptic weathers during the study period were classified into seven typical patterns using a semi-objective weather typing technique. Temporal and spatial variations of O3 and total oxidant (Ox = O3 + NO2) in Hong Kong were found to be closely connected with weather/circulation patterns. The highest O3 concentrations (25 ppbv in average) among the 7 categories were found to be associated with the influence of Northwest Pacific typhoons, whereas the lowest average concentrations (13 pbbv) were linked to southerly flow introduced by summer monsoons. Ozone episodes with hourly mixing ratios exceeding 120 ppbv were found to be caused primarily by regional transport under influence of the tropical cyclone and by photochemical reactions upon prevalence of anti-cyclonic circulation. Taking into account interannual variabilities in frequency and intensity of circulation patterns, a reconstructed time series of O3 captured up to 50% of the observed interannual variability and 36% of the increasing trend. The study highlights an important linkage between weather/climate and air quality.

Zhang, Yang; Mao, Huiting; Ding, Aijun; Zhou, Derong; Fu, Congbin

2013-07-01

239

A surface-based cloud observing system  

NASA Technical Reports Server (NTRS)

The paper describes a surface-based system, called the Cloud Observing System (COS), that was developed for measurements of the dynamical and thermodynamical properties of clouds and of their interaction with the large-scale environment, by combining several remote sensors and in situ systems. The atmospheric parameters that will be measured by COS include precipitation, the velocity and direction of wind, the cloud liquid water, the low-level winds and turbulence structure, integrated liquid and vapor quantities, the temperature and water profiles, the cloud radiance and the cloud base temperature, irradiances at the surface, the low-level temperature profile, the cloud-base height, and the cloud fraction; video cameras will provide visual records of clouds.

Albrecht, B. A.; Ackerman, T. P.; Thomson, D. W.; Mace, G.; Miller, M. A.; Peters, R. M.

1991-01-01

240

Weather Forecasting  

NSDL National Science Digital Library

Weather Forecasting is a set of computer-based learning modules that teach students about meteorology from the point of view of learning how to forecast the weather. The modules were designed as the primary teaching resource for a seminar course on weather forecasting at the introductory college level (originally METR 151, later ATMO 151) and can also be used in the laboratory component of an introductory atmospheric science course. The modules assume no prior meteorological knowledge. In addition to text and graphics, the modules include interactive questions and answers designed to reinforce student learning. The module topics are: 1. How to Access Weather Data, 2. How to Read Hourly Weather Observations, 3. The National Collegiate Weather Forecasting Contest, 4. Radiation and the Diurnal Heating Cycle, 5. Factors Affecting Temperature: Clouds and Moisture, 6. Factors Affecting Temperature: Wind and Mixing, 7. Air Masses and Fronts, 8. Forces in the Atmosphere, 9. Air Pressure, Temperature, and Height, 10. Winds and Pressure, 11. The Forecasting Process, 12. Sounding Diagrams, 13. Upper Air Maps, 14. Satellite Imagery, 15. Radar Imagery, 16. Numerical Weather Prediction, 17. NWS Forecast Models, 18. Sources of Model Error, 19. Sea Breezes, Land Breezes, and Coastal Fronts, 20. Soundings, Clouds, and Convection, 21. Snow Forecasting.

Nielsen-Gammon, John

1996-09-01

241

Predicting Weather and Understanding Weather Systems  

NSDL National Science Digital Library

The assignment requires students to observe the weather map in the newspaper for four consecutive days. On the first day they are instructed to choose a location somewhere in the country. The will record the weather conditions there and observe any weather systems that exist elsewhere in the country. They then make predictions of how they expect weather in their location to change over the subsequent three days.

Grandy, Carla

242

Observation and modelling of stable isotopes in precipitation for midlatitude weather systems in Melbourne, Australia  

NASA Astrophysics Data System (ADS)

The application of stable water isotopes as tracers of moisture throughout the hydrological cycle is often hindered by the relatively coarse temporal and spatial resolution of observational data. Intensive observation periods (IOPs) of isotopes in precipitation have been valuable in this regard enabling the quantification of the effects of vapour recycling, convection, cloud top height and droplet reevaporation (Dansgaard, 1953; Miyake et al., 1968; Gedzelman and Lawrence, 1982; 1990; Pionke and DeWalle, 1992; Risi et al., 2008; 2009) and have been used as a basis to develop isotope models of varying complexity (Lee and Fung, 2008; Bony et al., 2008). This study took a unified approach combining observation and modelling of stable isotopes in precipitation in an investigation of three key circulation types that typically bring rainfall to southeastern Australia. The observational component of this study involved the establishment of the Melbourne University Network of Isotopes in Precipitation (MUNIP). MUNIP was devised to sample rainwater simultaneously at a number of collection sites across greater Melbourne to record the spatial and temporal isotopic variability of precipitation during the passage of particular events. Samples were collected at half-hourly intervals for three specific rain events referred to as (1) mixed-frontal, (2) convective, and (3) stratiform. It was found that the isotopic content for each event varied over both high and low frequencies due to influences from local changes in rain intensity and large scale rainout respectively. Of particular note was a positive relationship between deuterium excess and rainfall amount under convective conditions. This association was less well defined for stratiform rainfall. As a supplement to the data coverage of the observations, the events were simulated using a version of NCAR CAM3 running with an isotope hydrology scheme. This was done by periodically nudging the model dynamics with data from the NCEP Reanalysis (Noone, 2006). Results from the simulations showed that the model represented well the large scale evolution of vapour profiles of deuterium excess and 18O for the mixed-frontal and stratiform events. Reconstruction of air mass trajectories provided further detail of the evolution and structure of the vapour profiles revealing a convergence of air masses from different source regions for the mixed-frontal event. By combining observations and modelling in this way, much detail of the structure and isotope moisture history of the observed events was provided that would be unavailable from the sampling of precipitation alone. References Bony, S., C. Risi, and F. Vimeux (2008), Influence of convective processes on the isotopic composition (?18O and ?D) of precipitation and water vapor in the tropics: 1. Radiative-convective equilibrium and Tropical Ocean-Global Atmosphere-Coupled Ocean-Atmosphere Response (TOGA-COARE) simulations, J. Geophys. Res., 113, D19305, doi:10.1029/2008JD009942. Dansgaard, W. (1953), The abundance of 18O in atmospheric water and water vapor. Tellus, 5, 461-469. Gedzelman, S. D., and J. R. Lawrence (1982), The isotopic composition of cyclonic precipitation. J. App. Met., 21, 1385-1404. Gedzelman, S. D., and J. R. Lawrence (1990), The isotopic composition of precipitation from two extratropical cyclones, Mon. Weather Rev., 118 , 495-509. Lee, J., and I. Fung (2008), 'Amount effect' of water isotopes and quantitative analysis of post-condensation processes, Hydrol. Process., 22, 1-8. Miyake, Y., O. Matsubaya, and C. Nishihara (1968), An isotopic study on meteoric precipitation, Pap. Meteorol. Geophys., 19, 243-266. Noone, D. (2006), Isotopic composition of water vapor modeled by constraining global climate simulations with reanalyses, in Research activities in atmospheric and oceanic modeling, J. Côté (ed.), Report No. 36, WMO/TD-No. 1347, p. 2.37-2.38. Pionke, H. B., and D. R. DeWalle (1992), Intra- and inter-storm 18O trends for selected rainstorms in Pennsylvania. J. Hydrol., 138, 131-143. Risi, C., S. Bony, and F. Vimeux (20

Barras, Vaughan; Simmonds, Ian

2010-05-01

243

Spatial Variability of the Depth of Weathered and Engineering Bedrock using Multichannel Analysis of Surface Wave Method  

NASA Astrophysics Data System (ADS)

In this paper an attempt has been made to evaluate the spatial variability of the depth of weathered and engineering bedrock in Bangalore, south India using Multichannel Analysis of Surface Wave (MASW) survey. One-dimensional MASW survey has been carried out at 58 locations and shear-wave velocities are measured. Using velocity profiles, the depth of weathered rock and engineering rock surface levels has been determined. Based on the literature, shear-wave velocity of 330 ± 30 m/s for weathered rock or soft rock and 760 ± 60 m/s for engineering rock or hard rock has been considered. Depths corresponding to these velocity ranges are evaluated with respect to ground contour levels and top surface levels have been mapped with an interpolation technique using natural neighborhood. The depth of weathered rock varies from 1 m to about 21 m. In 58 testing locations, only 42 locations reached the depths which have a shear-wave velocity of more than 760 ± 60 m/s. The depth of engineering rock is evaluated from these data and it varies from 1 m to about 50 m. Further, these rock depths have been compared with a subsurface profile obtained from a two-dimensional (2-D) MASW survey at 20 locations and a few selected available bore logs from the deep geotechnical boreholes.

Anbazhagan, P.; Sitharam, T. G.

2009-03-01

244

Ocean Tidal Loading and Surface Gravity Observations  

NASA Astrophysics Data System (ADS)

In a recent study, Ray et al. (2001) showed that the errors of the major semi-diurnal ocean tide M2 are larger than the precision of incoming space gravity missions be- cause of misestimates in shallow water areas. Since July 1997, the Global Geodynamics Project (GGP) network of about twenty superconducting gravimeters allows to study with an unprecedented accuracy surface gravity variations on a wide frequency domain. On the other hand, since the launch of Topex-Poseidon satellite in 1992 and the improvement of hydrodynamical tidal modeling, several accurate tidal models in both diurnal and semi-diurnal frequency bands are now available. We estimate the loading contribution of the eight major diurnal and semi-diurnal waves and compare them to the ocean tidal contribution observed with superconduct- ing gravimeters. Gravity variations are shown to be sensitive to sea height variations in a radius of about 3000-5000 kilometers around the stations. The differences between all tidal models are shown to be larger than the accuracy of each superconducting gravimeter. However there is still a discrepancy between all ocean tidal estimates and observed ocean tidal loading of about 0.1 microgal for most of GGP stations with phase shifts most often close to 0 degree. We also compare our computation of ocean tidal loading to other softwares provided by Agnew (1997), Matsumoto et al. (2001) and Scherneck (2001). The differences between tidal esti- mates using different softwares are also shown to be larger than the surface gravity measurement accuracy. For precise geodetic studies, further improvements of tidal loading computation are also needed, i.e. by refining the convolution of sea surface heights with the Green's functions computed for Earth models taking into account lateral heterogeneities in density and elasticity.

Boy, J. P.; Llubes, M.; Hinderer, J.; Florsch, N.

245

Spectral observations of 19 weathered and 23 fresh NEAs and their correlations with orbital parameters  

NASA Astrophysics Data System (ADS)

Results of our visible to near-infrared spectrophotometric observations of 41 near-Earth asteroids (NEAs) are reported. These moderate-resolution spectra, along with 14 previously published spectra from our earlier survey [Hicks, M.D., Fink, U., Grundy, W.M., 1998. Icarus 133, 69-78] show a preponderance of spectra consistent with ordinary chondrites (23 NEAs with this type of spectrum, along with 19 S-types and 13 in other taxonomic groups). There exists statistically significant evidence for orbit-dependent trends in our data. While S-type NEAs from our survey reside primarily in (1) Amor orbits or (2) Aten or Apollo orbits which do not cross the asteroid main-belt, the majority of objects with spectra consistent with ordinary chondrites in our survey are in highly eccentric Apollo orbits which enter the asteroid main-belt. This trend toward fresh, relatively unweathered NEAs with ordinary chondrite type spectra in highly eccentric Apollo orbits is attributed to one or a combination of three possible causes: (1) the chaotic nature of NEA orbits can easily result in high eccentricity orbits/large aphelion distances so that they can enter the collisionally enhanced environment in the main-belt, exposing fresh surfaces, (2) they have recently been injected into such orbits after a collision in the main-belt, or (3) such objects cross the orbits of several terrestrial planets, causing tidal disruption events that expose fresh surfaces.

Fevig, Ronald A.; Fink, Uwe

2007-05-01

246

Comparative Analysis of Thunderstorm Activity in the West Caucasus According to the Instrumental Measurements and Weather Stations Observations  

NASA Astrophysics Data System (ADS)

The number of thunderstorms days is one of the main characteristics of thunderstorms. In most cases, the number of days with different meteorological phenomena are the climate characteristic of the area. This characteristic is a common climate indicator. The comparative analysis of thunderstorms days quantity, received with lightning detector LS 8000 by Vaisala and weather stations of Krasnodar District (Russia), is presented. For this purpose the Krasnodar region was divided into 19 sites. The thunderstorm days amount and their comparison were conducted for each site according to the data of weather stations and LS 8000 lightning detectors. Totally 29 weather stations are located in this area. The number of thunderstorm days per year for the period of 2009-2012 was determined according to data, received from stations. It was received that average annual number of thunderstorm days for this area was from 33 to 39 days. The majority of thunderstorm days per year (up to 77) was registered in the south of Krasnodar region and on the Black Sea coast. The lowest thunderstorm activity (about 20 days) was observed in the North of the region. To compare visual and voice data for calculating thunderstorm days quantity of the Krasnodar region, the day was considered thundery if at least one weather station registered a storm. These instrumental observations of thunderstorms allow to obtain the basic characteristics and features of the distribution of thunderstorm activity over a large territory for a relatively short period of time. However, some characteristics such as thunderstorms intensity, damages from lightning flashes and others could be obtained only with instrumental observations. The territory of gathering thunderstorm discharges data by system LS8000 is limited by perimeter of 2250 km and square of 400 000 km2. According to the instrumental observations, the majority of storm activity also takes place on the Black Sea coast, near the cities of Sochi and Tuapse. Thus the number of thunderstorm days data characterized by the values from 49 to 158. To compare instrumental and visual-voice observations the difference between thunderstorms days quantity, obtained with visual-voice and instrumental methods, was selected as an indicator of thunderstorm activity. Total number of thunderstorm days in the Krasnodar region during 4 years is 565 according to the lightning detectors and 519 according to the weather stations. The presence of significant differences was revealed to compare number of thunderstorm days between instrumental observations and weather stations data. Thus the value of the average number of thunderstorms days on 29 meteorological stations of the Krasnodar region is reached 33-39 days. At the same time, 49-138 thunderstorm days were recorded according to the LS8000 system. This difference is caused by two factors: 1) limitations of visual-audio thunderstorms detection method at weather stations; 2) development of thunderstorms in a limited areas of the Krasnodar region, which is not the whole territory.

Knyazeva, Zalina; Gergokova, Zainaf; Gyatov, Ruslan; Boldyreff, Anton

2014-05-01

247

Cloud Observation and Modeling Test Bed for Air Force Weather Applications: Overview and First Results  

NASA Astrophysics Data System (ADS)

Air Force Weather (AFW) has documented requirements for real-time cloud analysis and short range cloud forecasts to support DoD missions around the world. To meet these needs, AFW utilizes the Cloud Depiction and Forecast System (CDFS) II system to develop a hourly cloud analysis and short range forecast. The system creates cloud masks from 16 different satellite sources and optimally merges them to create the analysis. This analysis then forms the initialization field for a short range 'advective' based cloud forecast. Northrop Grumman Corp. has recently delivered a CDFS II based Cloud Model Test Bed. This system offers the ability to test several aspects of the CDFS II system including: the effect of adding and subtracting sources of cloud imagery, the effect of changing source and skill of required external data sources, and the impact of changing the cloud information merge process among the various sources. In addition, the test bed offers a capability to generate a robust cloud modeling baseline against which to measure progress of a next generation Numerical Weather Prediction (NWP) based advanced data assimilation system. Finally, the test bed allows the development and testing of new cloud modeling validation techniques (and sources) to provide greater confidence in results generated from the test bed. This presentation will provide a basic overview of the CDFS II system and of the newly developed Test Bed and will include results from the first series of experiments conducted using the Test Bed.

Nobis, T. E.

2012-12-01

248

Observation of surface dark photovoltaic solitons.  

PubMed

Surface dark solitons in photovoltaic nonlinear media are reported. Taking advantage of diffusion and photovoltaic nonlinearities we demonstrated the surface dark solitons and their behaviors near surface theoretically and experimentally in LiNbO? crystal. It is very interesting that surface dark soliton is just half of dark soliton in bulk. Another interesting thing is that transverse modulation instability can be perfectly suppressed by surface dark soliton in virtue of surface. In addition, surface waveguides were written successfully utilizing surface dark soliton. PMID:23482012

Yang, Xi; Chen, Weiqiang; Yao, Peng; Zhang, Tianhao; Tian, Jianguo; Xu, Jingjun

2013-02-25

249

Weather Maps in Motion  

NSDL National Science Digital Library

In this activity, students learn to interpret current weather maps. They will observe weather map loop animations on the internet, learn the concept of Zulu time (Universal Time Coordinated, UTC) and visualize the movement of fronts and air masses. They will then analyze a specific weather station model, generate a meteogram from their observations, and answer a set of questions about their observations.

Burrows, Charles

250

Australian Severe Weather  

NSDL National Science Digital Library

The Australian Severe Weather Web site is maintained by self proclaimed severe weather enthusiasts Michael Bath and Jimmy Deguara. Other weatherphobes will fully appreciate what the authors have assembled. Everything from weather images, storm news, tropical cyclone data, bush fire and wild fire information, weather observation techniques, and even video clips and Web cam links. Although these other items make the site well rounded, the extensive amount of categorized weather pictures (which are quite extraordinary) are reason enough to visit.

251

What's the Weather?  

NSDL National Science Digital Library

In this lesson, students use daily observations, videos, and activities to learn about meteorology and the changing nature of weather. They will also identify weather events that are commonly reported in the news and discuss how weather affects lives. They should understand that weather can change daily and weather patterns change over the seasons, and that it has characteristics that can be measured and predicted. Suggestions for an optional field trip are also provided.

2005-01-01

252

GPS Water Vapor Estimation Using Interpolated Surface Meteorological Data from Australian Automatic Weather Stations  

Microsoft Academic Search

The existing GPS tracking networks established primarily for surveying, geodesy and navigation purposes may also be used for meteorology studies. This research uses hourly surface temperature and pressure (T & P) observations from Australia for GPS Precipitable Water Vapor (PWV) estimation. The paper outlines the basic meteorological data requirements, and presents experimental results to show the comparison between interpolated and

Zhengdong Bai; Yanming Feng

2003-01-01

253

Rain cell-based identification of the vertical profile of reflectivity as observed by weather radar and its use for precipitation uncertainty estimation  

NASA Astrophysics Data System (ADS)

The wide scale implementation of weather radar systems over the last couple of decades has increased our understanding concerning spatio-temporal precipitation dynamics. However, the quantitative estimation of precipitation by these devices is affected by many sources of error. A very dominant source of error results from vertical variations in the hydrometeor size distribution known as the vertical profile of reflectivity (VPR). Since the height of the measurement as well as the beam volume increases with distance from the radar, for stratiform precipitation this results in a serious underestimation (overestimation) of the surface reflectivity while sampling within the snow (bright band) region. This research presents a precipitation cell-based implementation to correct volumetric weather radar measurements for VPR effects. Using the properties of a flipping carpenter square, a contour-based identification technique was developed, which is able to identify and track precipitation cells in real time, distinguishing between convective, stratiform and undefined precipitation. For the latter two types of systems, for each individual cell, a physically plausible vertical profile of reflectivity is estimated using a Monte Carlo optimization method. Since it can be expected that the VPR will vary within a given precipitation cell, a method was developed to take the uncertainty of the VPR estimate into account. As a result, we are able to estimate the amount of precipitation uncertainty as observed by weather radar due to VPR for a given precipitation type and storm cell. We demonstrate the possibilities of this technique for a number of winter precipitation systems observed within the Belgian Ardennes. For these systems, in general, the precipitation uncertainty estimate due to vertical reflectivity profile variations varies between 10-40%.

Hazenberg, P.; Torfs, P. J. J. F.; Leijnse, H.; Uijlenhoet, R.

2012-04-01

254

The Effects of Chemical Weathering on Thermal-Infrared Spectral Data and Models: Implications for Aqueous Processes on the Martian Surface  

NASA Astrophysics Data System (ADS)

Chemical and mineralogical data from Mars shows that the surface has been chemically weathered on local to regional scales. Chemical trends and the types of chemical weathering products present on the surface and their abundances can elucidate information about past aqueous processes. Thermal-infrared (TIR) data and their respective models are essential for interpreting Martian mineralogy and geologic history. However, previous studies have shown that chemical weathering and the precipitation of fine-grained secondary silicates can adversely affect the accuracy of TIR spectral models. Furthermore, spectral libraries used to identify minerals on the Martian surface lack some important weathering products, including poorly-crystalline aluminosilicates like allophane, thus eliminating their identification in TIR spectral models. It is essential to accurately interpret TIR spectral data from chemically weathered surfaces to understand the evolution of aqueous processes on Mars. Laboratory experiments were performed to improve interpretations of TIR data from weathered surfaces. To test the accuracy of deriving chemistry of weathered rocks from TIR spectroscopy, chemistry was derived from TIR models of weathered basalts from Baynton, Australia and compared to actual weathering rind chemistry. To determine how specific secondary silicates affect the TIR spectroscopy of weathered basalts, mixtures of basaltic minerals and small amounts of secondary silicates were modeled. Poorly-crystalline aluminosilicates were synthesized and their TIR spectra were added to spectral libraries. Regional Thermal Emission Spectrometer (TES) data were modeled using libraries containing these poorly-crystalline aluminosilicates to test for their presence on the Mars. Chemistry derived from models of weathered Baynton basalts is not accurate, but broad chemical weathering trends can be interpreted from the data. TIR models of mineral mixtures show that small amounts of crystalline and amorphous silicate weathering products (2.5-5 wt.%) can be detected in TIR models and can adversely affect modeled plagioclase abundances. Poorly-crystalline aluminosilicates are identified in Northern Acidalia, Solis Planum, and Meridiani. Previous studies have suggested that acid sulfate weathering was the dominant surface alteration process for the past 3.5 billion years; however, the identification of allophane indicates that alteration at near-neutral pH occurred on regional scales and that acid sulfate weathering is not the only weathering process on Mars.

Rampe, Elizabeth Barger

255

Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations  

NASA Astrophysics Data System (ADS)

The International Space Station (ISS) space environments community utilizes near real time space weather data in support of a variety of ISS engineering and operations activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS from 2006 to the present time to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to the combined effects of electrostatic current collection processes from the plasma environment and inductive (vxB) effects due to the motion of the vehicle across the Earth's magnetic field. An ongoing effort to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and document ISS frame charging as the vehicle passes through regions of precipitating auroral electrons is challenged by restrictions on the available FPMU operation time. The instruments can only be operated during campaign periods limited to about a third of a year in accumulated operation time and FPMU data is down linked through the ISS Ku band telemetry system, a shared resource. As a result, FPMU campaign periods of a few days to weeks have typically been scheduled for periods of a week or two in advance. Capturing geomagnetic storm data under these conditions depended on the fortuitous event of a storm starting during a previously planned FPMU campaign period, an unlikely event at a time when Solar Cycle 24 was ending and a protracted solar minimum gave little in the way of geoeffective solar disturbances. However, with the start of Solar Cycle 24 the number of solar disturbances and associated geomagnetic storms started to increase and we modified our strategy to improve the chances of capturing geomagnetic storm data. We now monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have now been successful in capturing FPMU records from a number of geomagnetic storm periods including variations in ISS frame potential at high latitudes associated with geomagnetic activity that we interpret as auroral charging. In addition, space weather summaries were provided to ISS Expedition 30/31 crew along with predictions for upcoming auroral activity and estimates for times the ISS orbit would pass through regions of high magnetic latitude to enhance crew opportunities to image aurora from the ISS. This presentation will describe the near real time space weather resources utilized to predict FPMU operation times, summarize the results from FPMU operations during the geomagnetic storm periods, and provide examples of auroral images obtained by the ISS crew during recent storm periods from the spring and summer of 2012.

Minow, J. I.; Pettit, D. R.; Hartman, W. A.

2012-12-01

256

Two rare northern Entoloma species observed in Sicily under exceptionally cold weather conditions.  

PubMed

The biology and ecology of many Entoloma species is still poorly known as well as their geographical distribution. In Italy, there are no studies on the influence of weather on fungal abundance and richness and our knowledge on the ecology and distribution of Entoloma species needs to be improved. The discovery of two Entoloma species in Sicily (southern Italy), reported in the literature as belonging to the habitat of north European countries, was the basis leading to the assumption that anomalous climatic conditions could stimulate the growth of northern entolomas in the southernmost Mediterranean regions. The results of this study show that the presence of northern Entoloma species in Sicily is not influenced by the Mediterranean type of vegetation, by edaphic or altitudinal factors but by anomalous climatic trends of precipitations and temperatures which stimulate the fructification of basidiomata in correspondence with a thermal shock during autumn. PMID:22645481

Venturella, Giuseppe; Saitta, Alessandro; Mandracchia, Gerlando; Gargano, Maria Letizia

2012-01-01

257

Two Rare Northern Entoloma Species Observed in Sicily under Exceptionally Cold Weather Conditions  

PubMed Central

The biology and ecology of many Entoloma species is still poorly known as well as their geographical distribution. In Italy, there are no studies on the influence of weather on fungal abundance and richness and our knowledge on the ecology and distribution of Entoloma species needs to be improved. The discovery of two Entoloma species in Sicily (southern Italy), reported in the literature as belonging to the habitat of north European countries, was the basis leading to the assumption that anomalous climatic conditions could stimulate the growth of northern entolomas in the southernmost Mediterranean regions. The results of this study show that the presence of northern Entoloma species in Sicily is not influenced by the Mediterranean type of vegetation, by edaphic or altitudinal factors but by anomalous climatic trends of precipitations and temperatures which stimulate the fructification of basidiomata in correspondence with a thermal shock during autumn.

Venturella, Giuseppe; Saitta, Alessandro; Mandracchia, Gerlando; Gargano, Maria Letizia

2012-01-01

258

Characteristics of intense space weather events as observed from a low latitude station during solar minimum  

NASA Astrophysics Data System (ADS)

Using a dual-frequency high-resolution software-based GPS receiver, TEC and phase have been monitored from Calcutta, India situated near the northern crest of the Equatorial Ionization Anomaly for studying some Space Weather events during 2008-2010. Data from a dual-frequency Ionospheric TEC and Scintillation Monitor operational at this station under the international SCINDA program of the U.S. Air Force have also been used. This paper presents two cases of intense Space Weather events occurring in the equatorial latitudes under magnetically quiet conditions during the abnormally prolonged minimum of solar cycle 24. High values of S4 with maximum ˜0.8 were noted on GPS links located almost due south of Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N) when the look angles of the satellites are more-or-less aligned with the axis of the anisotropic field-aligned irregularities over the magnetic equator. Associated bite-outs in TEC of amplitude 40 units were recorded in the local post-sunset hours. Well-defined patches of phase scintillations and associated cycle slips were identified. On these days, higher values of ambient ionization were noted and the diurnal maximum of the electrojet strength was found to be delayed followed by a significant rise of the F region with a high upward drift velocity over the magnetic equator around sunset indicated by ionosonde. Measurements of in situ ion density using LEO DMSP corroborate the F region height rise. Presence of irregularities in ionization density distributions around 450km was found from C/NOFS measurements.

Paul, A.; Roy, B.; Ray, S.; Das, A.; Dasgupta, A.

2011-10-01

259

Weather Forecasting  

NSDL National Science Digital Library

Weather Forecasting is one of several online guides produced by the Weather World 2010 project at the University of Illinois. These guides use multimedia technology and the dynamic capabilities of the web to incorporate text, colorful diagrams, animations, computer simulations, audio, and video to introduce topics and concepts in the atmospheric sciences. This module introduces forecast methods and the numerous factors one must consider when attempting to make an accurate forecast. Sections include forecasting methods for different scenarios, surface features affecting forecasting, forecasting temperatures for day and night, and factors for forecasting precipitation.

2010-01-01

260

World Weather Watch: Global Observing System - Satellite sub-System. Information on the Application of Meteorological Satellite Data in Routine Operations and Research: Abstracts, Annual Summaries and Bibliographies.  

National Technical Information Service (NTIS)

Contributions from countries participating in the World Weather Watch program are listed. Emphasis is on the Global Observing System: Satellite sub-system. Bibliographic information and an abstract of each contribution are provided.

1978-01-01

261

Modeling land-surface processes and land-atmosphere interactions in the community weather and regional climate WRF model (Invited)  

NASA Astrophysics Data System (ADS)

The Weather Research and Forecasting (WRF) model has been widely used with high-resolution configuration in the weather and regional climate communities, and hence demands its land-surface models to treat not only fast-response processes, such as plant evapotranspiration that are important for numerical weather prediction but also slow-evolving processes such as snow hydrology and interactions between surface soil water and deep aquifer. Correctly representing urbanization, which has been traditionally ignored in coarse-resolution modeling, is critical for applying WRF to air quality and public health research. To meet these demands, numerous efforts have been undertaken to improve land-surface models (LSM) in WRF, including the recent implementation of the Noah-MP (Noah Multiple-Physics). Noah-MP uses multiple options for key sub-grid land-atmosphere interaction processes (Niu et al., 2011; Yang et al., 2011), and contains a separate vegetation canopy representing within- and under-canopy radiation and turbulent processes, a multilayer physically-based snow model, and a photosynthesis canopy resistance parameterization with a dynamic vegetation model. This paper will focus on the interactions between fast and slow land processes through: 1) a benchmarking of the Noah-MP performance, in comparison to five widely-used land-surface models, in simulating and diagnosing snow evolution for complex terrain forested regions, and 2) the effects of interactions between shallow and deep aquifers on regional weather and climate. Moreover, we will provide an overview of recent improvements of the integrated WRF-Urban modeling system, especially its hydrological enhancements that takes into account the effects of lawn irrigation, urban oasis, evaporation from pavements, anthropogenic moisture sources, and a green-roof parameterization.

Chen, F.; Barlage, M. J.

2013-12-01

262

Space Weathering Products Found on the Surfaces of the Itokawa Dust Particles: A Summary of the Initial Analysis  

NASA Technical Reports Server (NTRS)

Surfaces of airless bodies exposed to interplanetary space gradually have their structures, optical properties, chemical compositions, and mineralogy changed by solar wind implantation and sputtering, irradiation by galactic and solar cosmic rays, and micrometeorite bombardment. These alteration processes and the resultant optical changes are known as space weathering [1, 2, 3]. Our knowledge of space weathering has depended almost entirely on studies of the surface materials returned from the Moon and regolith breccia meteorites [1, 4, 5, 6] until the surface material of the asteroid Itokawa was returned to the Earth by the Hayabusa spacecraft [7]. Lunar soil studies show that space weathering darkens the albedo of lunar soil and regolith, reddens the slopes of their reflectance spectra, and attenuates the characteristic absorption bands of their reflectance spectra [1, 2, 3]. These changes are caused by vapor deposition of small (<40 nm) metallic Fe nanoparticles within the grain rims of lunar soils and agglutinates [5, 6, 8]. The initial analysis of the Itokawa dust particles revealed that 5 out of 10 particles have nanoparticle-bearing rims, whose structure varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles (npFe) exist in a thin (5-15 nm) surface layer (zone I) on olivine, low-Ca pyroxene, and plagioclase, suggestive of vapor deposition. Sulfur-free npFe exist deeper inside (<60 nm) ferromagnesian silicates (zone II). Their texture suggests formation by amorphization and in-situ reduction of Fe2+ in ferromagnesian silicates [7]. On the other hand, nanophase metallic iron (npFe0) in the lunar samples is embedded in amorphous silicate [5, 6, 8]. These textural differences indicate that the major formation mechanisms of the npFe0 are different between the Itokawa and the lunar samples. Here we report a summary of the initial analysis of space weathering of the Itokawa dust particles.

Noguchi, T.; Kimura, M.; Hashimoto, T.; Konno, M.; Nakamura, T.; Ogami, T.; Ishida, H.; Sagae, R.; Tsujimoto, S.; Tsuchiyama, A,; Zolensky, M. E.; Tanaka, M.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

2012-01-01

263

A simple parameterization of the short-wave aerosol optical properties for surface direct and diffuse irradiances assessment in a numerical weather model  

NASA Astrophysics Data System (ADS)

Broadband short-wave (SW) surface direct and diffuse irradiances are not typically within the set of output variables produced by numerical weather prediction (NWP) models. However, they are frequently requested for solar energy applications. In order to compute them, a detailed representation of the aerosol optical properties is important. Nonetheless, NWP models typically oversimplify aerosol representation or even neglect their effect. In this work, a flexible method to account for the SW aerosol optical properties in the computation of broadband SW surface direct and diffuse irradiances is presented. It only requires aerosol optical depth at 0.55 ?m and knowledge of the type of predominant aerosol. Other parameters needed to consider spectral aerosol extinction, namely, Angström exponent, aerosol single-scattering albedo and aerosol asymmetry factor, are parameterized. The parameterization has been tested using the Rapid Radiative Transfer Model for climate and weather models (RRTMG) SW scheme of the Weather Research and Forecasting (WRF) NWP model for data over the continental US. In principle, it can be adapted to any other SW radiative transfer band model. It has been verified against a control experiment and using data from five radiometric stations in the contiguous US. The control experiment consisted of a clear-sky evaluation of the RRTMG solar radiation estimates obtained in WRF when RRTMG is driven with ground-observed aerosol optical properties. Overall, the verification has shown satisfactory results for both broadband SW surface direct and diffuse irradiances. The parameterization has proven effective in significantly reducing the prediction error and constraining the seasonal bias in clear-sky conditions to within the typical observational error expected in well maintained radiometers.

Ruiz-Arias, J. A.; Dudhia, J.; Gueymard, C. A.

2014-06-01

264

Comparative study of pulsed laser cleaning applied to weathered marble surfaces  

NASA Astrophysics Data System (ADS)

The removal of unwanted matter from surface stones is a demanding task in the conservation of cultural heritage. This paper investigates the effectiveness of near-infrared (IR) and ultraviolet (UV) laser pulses for the cleaning of surface deposits, iron oxide stains and different types of graffiti (black, red and green sprays and markers, and black cutting-edge ink) on dolomitic white marble. The performance of the laser techniques is compared to common cleaning methods on the same samples, namely pressurized water and chemical treatments. The degree of cleaning achieved with each technique is assessed by means of colorimetric measurements and X-ray microfluorescence. Eventual morphological changes induced on the marble substrate are monitored with optical and electronic microscopy. It is found that UV pulsed laser ablation at 266 nm manages to clean all the stains except the cutting-edge ink, although some degree of surface erosion is produced. The IR laser pulses at 1064 nm can remove surface deposits and black spray acceptably, but a yellowing is observed on the stone surface after treatment. An economic evaluation shows that pulsed laser cleaning techniques are advantageous for the rapid cleaning of small or inaccessible surface areas, although their extensive application becomes expensive due to the long operating times required.

Ortiz, P.; Antúnez, V.; Ortiz, R.; Martín, J. M.; Gómez, M. A.; Hortal, A. R.; Martínez-Haya, B.

2013-10-01

265

A statistical-dynamical scheme for reconstructing ocean forcing in the Atlantic. Part I: weather regimes as predictors for ocean surface variables  

NASA Astrophysics Data System (ADS)

The links between the observed variability of the surface ocean variables estimated from reanalysis and the overlying atmosphere decomposed in classes of large-scale atmospheric circulation via clustering are investigated over the Atlantic from 1958 to 2002. Daily 500 hPa geopotential height and 1,000 hPa wind anomaly maps are classified following a weather-typing approach to describe the North Atlantic and tropical Atlantic atmospheric dynamics, respectively. The algorithm yields patterns that correspond in the extratropics to the well-known North Atlantic-Europe weather regimes (NAE-WR) accounting for the barotropic dynamics, and in the tropics to wind classes (T-WC) representing the alteration of the trades. 10-m wind and 2-m temperature (T2) anomaly composites derived from regime/wind class occurrence are indicative of strong relationships between daily large-scale atmospheric circulation and ocean surface over the entire Atlantic basin. High temporal correlation values are obtained basin-wide at low frequency between the observed fields and their reconstruction by multiple linear regressions with the frequencies of occurrence of both NAE-WR and T-WC used as sole predictors. Additional multiple linear regressions also emphasize the importance of accounting for the strength of the daily anomalous atmospheric circulation estimated by the combined distances to all regimes centroids in order to reproduce the daily to interannual variability of the Atlantic ocean. We show that for most of the North Atlantic basin the occurrence of NAE-WR generally sets the sign of the ocean surface anomaly for a given day, and that the inter-regime distances are valuable predictors for the magnitude of that anomaly. Finally, we provide evidence that a large fraction of the low-frequency trends in the Atlantic observed at the surface over the last 50 years can be traced back, except for T2, to changes in occurrence of tropical and extratropical weather classes. All together, our findings are encouraging for the prospects of basin-scale ocean dynamical downscaling using a weather-typing approach to reconstruct forcing fields for high resolution ocean models (Part II) from coarse resolution climate models.

Cassou, Christophe; Minvielle, Marie; Terray, Laurent; Périgaud, Claire

2011-01-01

266

Observed Changes at the Surface of the Arctic Ocean  

NASA Astrophysics Data System (ADS)

The Arctic has long been considered a harbinger of global climate change since simulations with global climate models predict that if the concentration of CO2 in the atmosphere doubles, the Arctic would warm by more than 5°C, compared to a warming of 2°C for subpolar regions (Manabe et al., 1991). And indeed, studies of the observational records show polar amplification of the warming trends (e.g. Serreze and Francis, 2004). These temperature trends are accompanied by myriad concurrent changes in Arctic climate. One of the first indicators of Arctic climate change was found by Walsh et al. (1996) using sea level pressure (SLP) data from the International Arctic Buoy Programme (IABP, http://iabp.apl.washington.edu). In this study, they showed that SLP over the Arctic Ocean decreased by over 4 hPa from 1979 - 1994. The decreases in SLP (winds) over the Arctic Ocean, forced changes in the circulation of sea ice and the surface ocean currents such that the Beaufort Gyre is reduced in size and speed (e.g. Rigor et al., 2002). Data from the IABP has also been assimilated into the global surface air temperature (SAT) climatologies (e.g. Jones et al. 1999), and the IABP SAT analysis shows that the temperature trends noted over land extend out over the Arctic Ocean. Specifically, Rigor et al. (2000) found warming trends in SAT over the Arctic Ocean during win¬ter and spring, with values as high as 2°C/decade in the eastern Arctic during spring. It should be noted that many of the changes in Arctic climate were first observed or explained using data from the IABP. The observations from IABP have been one of the cornerstones for environmental forecasting and studies of climate and climate change. These changes have a profound impact on wildlife and people. Many species and cultures depend on the sea ice for habitat and subsistence. Thus, monitoring the Arctic Ocean is crucial not only for our ability to detect climate change, but also to improve our understanding of the Arctic and global climate system, and for forecasting weather and sea ice conditions. The IABP provides the longest continuing record of observations for the Arctic Ocean.

Ortmeyer, M.; Rigor, I.

2004-12-01

267

Heterogeneous distribution of nanophase aluminosilicate weathering products: Interpreting Martian weathering  

NASA Astrophysics Data System (ADS)

Nanocrystalline alteration products form in a range of soil and regolith weathering environments on Earth. In some weathering systems, poorly crystalline aluminosilicates such as allophane are distributed heterogeneously, as a function of depth in a vertical weathering profile or as a function of micro-environmental factors. Both of these factors can be important for understanding weathering processes on Earth and are particularly important to consider when interpreting allophane on Mars. Chemical and mineralogical measurements of Mars could be confounded by a vertical heterogeneity common to many weathering systems, because what is observed at the surface by spacecraft may not be representative of the complete weathering system. Appropriate caution should be taken to compare surface measurements of Mars to terrestrial weathering environments that examine soil columns. Also, nanocrystalline aluminosilicates are known to form coatings on regolith particles and rock fragments and can be compositionally distinct from weathering products formed in the greater regolith matrix. These types of coatings are particularly important to consider for interpreting remotely sensed spectral measurements because fragmented rocks, from sand to boulders, comprise much of the relatively dust-free surfaces of Mars. Due to their strong influence on spectral observations, coatings could be strongly detectable by thermal infrared spectroscopy relative to coexisting, weakly aggregated fine-grained weathering products, resulting in the oversampling of coatings. Consequently, detected nanocrystalline aluminosilicates phases may not represent the overall weathering system. As an example of these influences, we will consider the high-silica material(s) detected in Mars northern plains. Although there are several models for how this material formed, if it formed by in situ regolith weathering then the high-silica material was precipitated from dissolved regolith materials. Evidence for extensive cryoturbation in the northern plains indicates that subsurface materials have been brought to the surface, thus any vertical compositional heterogeneity resulting from weathering may have been subsequently homogenized. However, small-scale compositional heterogeneities could persist. Although high-silica material may coat particulates that comprise much of the surface, it may only represent only a micro-environment of the subsurface weathering. For example, although we suggest that the northern plains contain a silica-rich allophanic phase, weathering may also have produced more aluminous phases that are undetected in spectra because they do not form coatings. In addition, we will consider the possibility that Martian weathering produces poorly crystalline aluminosilicate phases that are structurally different from true allophane. We will report on the thermal infrared spectral difference between these phases. The details of Martian weathering processes that can be inferred from detection of allophane are limited by how well vertical and micro-environmental heterogeneities are understood and compensated for, for which input from the terrestrial weathering and soil science communities is essential.

Kraft, M. D.; Sharp, T. G.; Rampe, E. B.

2011-12-01

268

Rainfall forecasting in a mountainous region using a weather radar and ground meteorological observations  

NASA Astrophysics Data System (ADS)

Weather radars provide several types of information useful for defining the state and evolution of a rain system: the rainfall rate, the vertically integrated rainwater content, and the advection velocity. The very short-term rainfall forecasting models dedicated to the survey of catchments (particularly those subject to flash-floods) are typically designed to include one or more of these information types. A general formulation of these models associating an advective term and a dynamical term is proposed by Lee and Georgakakos (1991). The model proposed in this work extends the simplified dynamical formulation developed by Seo and Smith (1992) and French and Krajewski (1994) by explicitly accounting for orographic enhancement and by combining the dynamical component with an advection-diffusion scheme (Smolarkiewicz 1983). This paper presents an initial evaluation of the model for two rain events in the mountainous Cevennes region located in the South of France. One-hour and two-hour lead-time forecasts for four catchments are performed and compared with two simple methods: persistence and advection.

Dolciné, L.; Andrieu, H.; French, M. N.

269

Space Weather  

NASA Astrophysics Data System (ADS)

This volume provides a comprehensive overview of our current observational knowledge, theoretical understanding, and numerical capability with regard to the phenomena known as space weather. Space weather refers to conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems, and can endanger human life or health. The rapid advance in these technologies has provided us with unprecedented capability and convenience, and we have come to rely on them more and more. Technology has reduced society's risk to many kinds of natural disasters, but through its own vulnerability, it has actually increased society's risk to space weather. Adverse conditions in the space environment can cause disruption of satellite operations, communications, navigation, and electric power distribution grids, leading to a variety of socioeconomic losses.

Song, Paul; Singer, Howard J.; Siscoe, George L.

270

Weathering of iron sulfides and concrete alteration: Thermodynamic model and observation in dams from central Pyrenees, Spain  

SciTech Connect

The concrete of the Graus and Tabescan dams present significant durability problems. The cement paste is altered to expansive phases such as ettringite and gypsum, following fractures and aggregate-paste interfaces. The alteration is initially attributed to the acidic solution produced by the weathering of the pyrrhotite contained in the aggregate fragments. A chemical model, based on ion association and thermodynamic equilibrium, permits the calculation of the mass transfer between the solids and the pore solution, and the prediction of the progress of the acidic attack. The results of the calculations have been compared with the alteration features observed in concrete of these dams. Despite the simplifications, this model is able to predict the observed alteration stages, and confirms the hypothesis of acidic-sulfatic alteration of the cement.

Ayora, C. [Inst. de Ciencias de la Tierra, Barcelona (Spain)] [Inst. de Ciencias de la Tierra, Barcelona (Spain); Chinchon, S. [Univ. de Alicante (Spain). Dept. de Construcciones Arquitectonicas] [Univ. de Alicante (Spain). Dept. de Construcciones Arquitectonicas; Aguado, A.; Guirado, F. [Univ. Politecnica de Catalunya (Spain). Dept. de Ingenieria de la Construccion] [Univ. Politecnica de Catalunya (Spain). Dept. de Ingenieria de la Construccion

1998-04-01

271

Comparison of Approaches to Calibrate a Surface Complexation Model for U(VI) Sorption to Weathered Saprolite  

SciTech Connect

A surface complexation model describing the sorption of uranyl ions and uranyl carbonate on weak and strong sites was used to analyze experiments on pH-dependent U(VI) sorption to weathered shale/limestone saprolite. Sorption data were collected at two different solid to solution ratios. Various methods of estimating equilibrium reaction coefficients and site densities were investigated. As a first approximation, extractable iron oxides were assumed to behave as ferrihydrite with reaction coefficients as reported by Waite et al. (1994). A generalized composite (GC) approach was then employed with coefficients estimated by an inverse modeling method applied both in a stepwise fashion and simultaneously to whole data set. Uncertainty in model parameters and predictions was lowest using the simultaneous inverse method, but results from the stepwise method were very similar. The generalized reaction network accurately described pH-dependent U(VI) sorption on weathered saprolite between pH 4 to 9.

Zhang, Fan [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Brooks, Scott C [ORNL; Kim, Young Jin [ORNL; Tang, Guoping [ORNL; Jardine, Philip M [ORNL; Watson, David B [ORNL

2009-01-01

272

Space Weathering Processes on Mercury  

NASA Technical Reports Server (NTRS)

Like the Moon, Mercury has no atmosphere to protect it from the harsh space environment and therefore it is expected that it will incur the effects of space weathering. These weathering processes are capable of both creating regolith and altering its optical properties. However, there are many important differences between the environments of Mercury and the Moon. These environmental differences will almost certainly affect the weathering processes as well as the products of those processes. It should be possible to observe the effects of these differences in Vis/NIR spectra of the type expected to be returned by MESSENGER. More importantly, understanding these weathering processes and their consequences is essential for evaluating the spectral data returned from MESSENGER and other missions in order to determine the mineralogy and the iron content of the Mercurian surface. Theoretical and experimental work has been undertaken in order to better understand these consequences.

Noble, S. K.; Pieters, C. M.

2002-01-01

273

Vertical structure of the wind field during the Special Observing Period I of the Global Weather Experiment  

NASA Technical Reports Server (NTRS)

The vertical structure of the global atmosphere is analyzed for selected periods of the Special Observing Period I (SOP-I) for the Global Weather Experiment (GWE). The analysis consists of projection of the stream-function and velocity potential at 200 and 850 mb on spherical harmonics and of the wind and height fields on the normal modes of a linearized form of the primitive equations for a basic state at rest. The kinematic vertical structure is discussed in terms of correlation coefficients of the 200 mb and 850 mb winds and analysis of the internal and external normal modes of the primitive equations. The reliability of the results is checked by applying the same analysis methods to data sets obtained from three different institutions: Geophysical Fluid Dynamics Laboratory (GFDL), European Center for Medium Range Weather Forecasting (ECMWF), and Goddard Laboratory for the Atmospheres (GLA). It is found that, on a global basis, vertically reversing circulations are as important as the equivalent barotropic structures. For the verticaly reversing components, the gravity and mixed Rossby-gravity modes have contributions of the same order of magnitude as those of the Rossby modes in tropical latitudes.

Paegle, J. N.; Paegle, J.; Zhen, Z.; Sampson, G.

1986-01-01

274

Aquarius Observations of Sea Surface Salinity  

NASA Video Gallery

This visualization shows changes in global sea surface salinity, as measured by NASAâ??s Aquarius instrument aboard the Aquarius/SAC-D spacecraft, from December 2011 through December 2012. Red repr...

275

Putting Weather into Weather Derivatives  

NASA Astrophysics Data System (ADS)

Just as weather forecasting has a colorful and often farsighted history within geophysics, financial mathematics has a long and turbulent history within mathematics. Thus it is no surprise that the intersection of real physics and real financial mathematics provides a rich source of problems and insight in both fields. This presentation targets open questions in one such intersection: quantifying ``weather risk.'' There is no accepted (operational) method for including deterministic information from simulation models (numerical weather forecasts, either best guess or by ensemble forecasting methods), into the stochastic framework most common within financial mathematics. Nor is there a stochastic method for constructing weather surrogates which has been proven successful in application. Inasmuch as the duration of employable observations is short, methods of melding short term, medium-range and long term forecasts are needed. On these time scales, model error is a substantial problem, while many methods of traditional statistical practice are simply inappropriate given our physical understanding of the system. A number of specific open questions, along with a smaller number of potential solutions, will be presented. >http://www.maths.ox.ac.uk/~lenny/WeatherRisk

Smith, L. A.; Smith, L. A.

2001-12-01

276

Seasonal changes in Titan's weather patterns and the evolution and implications of accompanying surface changes  

NASA Astrophysics Data System (ADS)

Post-equinox changes in Titan's atmospheric circulation brought clouds and extensive methane rain to Titan's low latitudes [1,2]. Observations by Cassini ISS over the ~2 years since the storm revealed most of the changes to be short-lived; only a few darkened patches persisted through Fall 2011. In an unsaturated permeable medium, infiltration rates exceed 20 mm/week [3], so persistence of surface liquids over several months suggests either a shallow impermeable layer or that the local methane table lies close to the surface. Evaporation rates greater than 1 mm/week are predicted in equatorial regions [4] and rates of 20 mm/week have been documented at Titan's poles [5], thus areas where darkening persisted must be saturated ground at the level of a methane table or have had liquid ponded to depths of 2.5-50 cm. Several smaller areas of surface brightening were also observed, a phenomenon that is less well understood. Cassini VIMS spectra of these regions do not match those of clouds or other surface units [6, 7]. Interpretations include cleaning by runoff [2] or deposition of a fine-grained volatile solid as the result of evaporative cooling [6, 7]. In general, brightening has persisted longer than darkening, but these areas are also reverting to their original appearance, which could constrain rates of evaporation/sublimation of the bright material or re-deposition of darker hydrocarbons by aeolian transport or precipitation from the atmosphere. Cassini and Earth-based observers monitor Titan frequently (typically at least a few times per month), but few clouds have been observed since Fall 2010, which may indicate that enough methane was removed from the atmosphere and the lapse rate stabilized sufficiently that activity will not resume until the onset of convection at mid-northern latitudes later in northern spring. A similar lapse followed a 2004 outburst of south-polar clouds [8], which also appeared to produce significant rainfall [9]. [1] Turtle et al., GRL 38, L03203, doi:10.1029/2010GL046266, 2011. [2] Turtle et al., Science 331, 10.1126/science.1201063. 2011. [3] Hayes et al., GRL 35, L09204, 2008. [4] Schneider et al., Nature 481, doi:10.1038/nature10666, 2012. [5] Hayes et al., Icarus 211, 2011. [6] Barnes et al., LPSC XXXXIII, 2012. [7] Barnes et al., in revision. [8] Schaller et al., Icarus 184, 2006. [9] Turtle et al., GRL 36, L02204, doi:10.1029/2008GL036186, 2009.

Turtle, E. P.; Perry, J.; McEwen, A. S.; Barbara, J. M.; Del Genio, A. D.; West, R. A.; Barnes, J. W.; Hayes, A.; Lorenz, R. D.; Lunine, J. I.; Stofan, E. R.; Schaller, E. L.; Lopes, R. M.; Ray, T. L.

2012-12-01

277

Dynamic model for space-time weather radar observation and nowcasting  

NASA Astrophysics Data System (ADS)

A general framework of the dynamic model for space-time radar observations has been developed in the current research. There exist three difficulties in modeling space-time radar observations: (1) high dimensionality due to the high-resolution radar measurements over a large area, (2) non-stationarity due to the storm motion, and (3) nonstationarity due to evolution (growth and decay). These difficulties are addressed in this research. To deal with the storm motion, an efficient radar storm tracking algorithm is developed in the spectral domain. Based on this new technique, the Dynamic and Adaptive Radar Tracking of Storms (DARTS) is developed and evaluated using the synthesized and the observed radar reflectivity. To tackle the high dimensionality and model the spatial variability of radar observations, a general modeling framework is formulated and the singular value decomposition (SVD) is used for dimension reduction. To deal with the dynamic evolution and model the temporal variability of radar observations, the motion-compensated temporal alignment (MCTA) transformation is developed. In this analysis the evolution of radar storm fields is modeled by the linear dynamic system (LDS) in the low-dimensional subspace. The applications of the dynamic model for space-time radar observations are further demonstrated. Spatial and dynamic characteristics are obtained based on the estimated model parameters using three months of radar observations. The characteristic temporal scales are quantified for this dataset. The correlation between the temporal characterization and the spatial characterization of observed radar fields are explored. The simulation capability of different spatiotemporal radar reflectivity fields is demonstrated. Evaluation of the space time variability is particularly important in the context of adaptive scanning of storm systems. The short-term prediction of radar reflectivity fields based on the space-time dynamic model is evaluated using observed radar data. The simulations of the DARTS for real-time applications are also conducted and evaluated.

Xu, Gang

278

Evaluating the Impacts of NASA/SPoRT Daily Greenness Vegetation Fraction on Land Surface Model and Numerical Weather Forecasts  

NASA Technical Reports Server (NTRS)

The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed a Greenness Vegetation Fraction (GVF) dataset, which is updated daily using swaths of Normalized Difference Vegetation Index data from the Moderate Resolution Imaging Spectroradiometer (MODIS) data aboard the NASA EOS Aqua and Terra satellites. NASA SPoRT began generating daily real-time GVF composites at 1-km resolution over the Continental United States (CONUS) on 1 June 2010. The purpose of this study is to compare the National Centers for Environmental Prediction (NCEP) climatology GVF product (currently used in operational weather models) to the SPoRT-MODIS GVF during June to October 2010. The NASA Land Information System (LIS) was employed to study the impacts of the SPoRT-MODIS GVF dataset on a land surface model (LSM) apart from a full numerical weather prediction (NWP) model. For the 2010 warm season, the SPoRT GVF in the western portion of the CONUS was generally higher than the NCEP climatology. The eastern CONUS GVF had variations both above and below the climatology during the period of study. These variations in GVF led to direct impacts on the rates of heating and evaporation from the land surface. In the West, higher latent heat fluxes prevailed, which enhanced the rates of evapotranspiration and soil moisture depletion in the LSM. By late Summer and Autumn, both the average sensible and latent heat fluxes increased in the West as a result of the more rapid soil drying and higher coverage of GVF. The impacts of the SPoRT GVF dataset on NWP was also examined for a single severe weather case study using the Weather Research and Forecasting (WRF) model. Two separate coupled LIS/WRF model simulations were made for the 17 July 2010 severe weather event in the Upper Midwest using the NCEP and SPoRT GVFs, with all other model parameters remaining the same. Based on the sensitivity results, regions with higher GVF in the SPoRT model runs had higher evapotranspiration and lower direct surface heating, which typically resulted in lower (higher) predicted 2-m temperatures (2-m dewpoint temperatures). Portions of the Northern Plains states experienced substantial increases in convective available potential energy as a result of the higher SPoRT/MODIS GVFs. These differences produced subtle yet quantifiable differences in the simulated convective precipitation systems for this event.

Bell, Jordan R.; Case, Jonathan L.; LaFontaine, Frank J.; Kumar, Sujay V.

2012-01-01

279

The influence of dynamic vegetation models including harvest and fertilization management on the energy fluxes and the feedback effects between the weather and the land surface models  

NASA Astrophysics Data System (ADS)

Recent studies show that uncertainties in regional and global weather and climate simulations are partly caused by inadequate descriptions of the soil-plant-atmosphere system. Particularly relevant for the improvement of regional weather forecast are models which better describe the feedback fluxes between the land surface and the atmosphere, which influences surface temperature, surface air pressure and the amount and frequency of precipitation events. Aim of this study was to examine the differences between weather simulation results by the "Regional Climate and Weather Forecast Model" (WRF) using either the frequently applied land surface model NOAH or Expert-N. Where the standard model NOAH distinguish between vegetation class specific monthly changing soil cover values (leaf area index) and defined soil characteristics, Expert-N is an ecosystem model that allows the application of more mechanistic soil and plant sub-models including the management of soil and vegetation and effects of water and nutrient availability on plant growth are considered. The WRF-NOAH model was applied with a default land surface configuration typical for the simulation domain Bavaria, Germany. Expert-N was configured using the Hurley Pasture Model to simulate plant growth and calibrated using vegetation, management and soil data from one grassland site. Both models were applied to the simulation domain. The simulation results of energy fluxes in both models between the land surface and the atmosphere were compared with each other's and with weather data from about 100 weather stations in Bavaria using statistical methods. The influence of different harvest scenarios on the energy fluxes is discussed. The simulation shows the high impact of vegetation management on the energy fluxes which caused significant differences between weather characteristics such as the simulated surface temperatures and precipitation events on the regional scale. Therefore, we conclude that weather forecast on the regional scale could be significantly improved by modeling approaches that better describe the dynamic of vegetation growth.

Klein, Christian; Biernath, Christian; Thieme, Christoph; Heinlein, Florian; Priesack, Eckart

2014-05-01

280

On the Use of QuikSCAT Scatterometer Measurements of Surface Winds for Marine Weather Prediction  

Microsoft Academic Search

The value of Quick Scatterometer (QuikSCAT) measurements of 10-m ocean vector winds for marine weather prediction is investigated from two Northern Hemisphere case studies. The first of these focuses on an intense cyclone with hurricane-force winds that occurred over the extratropical western North Pacific on 10 January 2005. The second is a 17 February 2005 example that is typical of

Dudley B. Chelton; Michael H. Freilich; Joseph M. Sienkiewicz; Joan M. Von Ahn

2006-01-01

281

A sub-regional climate cluster analysis over Italy from regional climate model simulation and weather station observations  

NASA Astrophysics Data System (ADS)

High resolution Regional Climate Models (RCMs) are a key tools in producing downscaled and calibrated outputs for impact studies where local scale climate information are needed. Recent studies suggest that in the processing chain that goes from the global scale climate projection to the local scale information, the use of an intermediate scale RCM increases the quality of the climate information produced at the local scale. We propose a direct assessment of the type of improvements achieved by using RCMs for producing the intermediate scale climate information required for example in impact studies. We use relatively long (50 years) daily climate records of 64 weather stations in Italy the evaluate how the ENEA-PROTHEUS system reconstruct the sub-regional climate clusters emerging from observation at a spatial scale finer than the one of the global driver. Specifically, on one side we tested the capability of ENEA-PROTHEUS regional coupled model, run in a 'perfect boundaries' mode using ERA-40, to capture the pattern of sub-regional climate spatial clusters relative to maximum/minimum temperature and rainfall. On the other hand, we considered the spatial averages of these parameters on the sub-regional climate spatial clusters. We compare the model output and the weather station data in terms of their representation of the mean seasonal cycle, the corresponding interannual variability and large deviations. We find a close agreement between model and observations. In particular, although biases in the modelled seasonal cycle are present, the model is able to reproduce the frequency and the seasonality of intense events for all seasons, including hot and cold spells and intense rainfalls, especially for alpine regions.

Calmanti, Sandro; Maimone, Filippo; Dell'Aquila, Alessandro; Ciciulla, Fabrizio

2013-04-01

282

Annual carbon dioxide cycle in a montane soil: observations, modeling, and implications for weathering  

Microsoft Academic Search

Profiles of COâ concentrations in soil and snow, soil respiration, soil and snow temperatures, and shallow ground water chemistry were monitored from March 1984 to July 1985 in a montane region neat Brighton, Utah. Significant seasonal variations in the concentrations of COâ in soil and snow occurred, and two principal rise-decline cycles were observed. During the first cycle the concentration

D. Kip Solomon; Thure E. Cerling

1987-01-01

283

Observations of Hurricane Bonnie in spaceborne synthetic aperture radar (SAR) and next-generation Doppler weather radar (NEXRAD)  

Microsoft Academic Search

Atmospheric circulation systems have being shown to produce observable signatures on spaceborne synthetic aperture radar (SAR) imagery of the ocean surface. Capillary and small gravity ocean waves of roughly the scale of the SAR electromagnetic wavelength, the so-called Bragg waves, provide the surface roughness that allows for SAR mapping of both ocean and atmospheric mesoscale features. Two RADARSAT SAR images

Pablo Clemente-Colon; Peter C. Manousos; William G. Pichel; Karen Friedman

1999-01-01

284

Impact of Kalpana-1 derived land surface albedo on short-range weather forecasting over the Indian subcontinent  

NASA Astrophysics Data System (ADS)

skill of weather forecasts at high spatial resolution depends on accurate representation of land surface states at appropriate spatial and temporal scales that modulate flux partitioning in the numerical weather prediction models. In this study, the Weather Research and Forecasting (WRF) model is customized to assess the impact of land surface albedo (LSA) derived from Kalpana-1 Very High Resolution Radiometer (K1VHRR) in comparison to default monthly climatological albedo from the United States Geological Survey (USGS). A two-stage upscaling of ground-measured albedo from Agro-Met Stations is performed to derive K1VHRR LSA. This combines multispectral reflectance at intermediate scales from the Advanced Wide Field Sensor on board Resourcesat-2 at Low Earth Orbiting platform and the planetary (Earth-atmosphere system) albedo from Kalpana-1 visible band at Geostationary Earth Orbiting platform. Two separate experiments, with real-time K1VHRR LSA and USGS climatological LSA (CNT), are performed to evaluate the impact of real-time K1VHRR LSA on daily WRF model forecasts during July 2009. Additional experiments are performed to assess the impact of real-time and climatological K1VHRR albedo against USGS climatological albedo based experiment. Results show that real-time K1VHRR albedo improves the surface temperature, specific humidity, and wind speed forecasts as compared to CNT experiments. The impact of climatological and real-time K1VHRR LSA is small compared to the advantage of using K1VHRR over USGS. Moreover, real-time K1VHRR albedo has additional benefits to improve the representation of seasonal variability. Results show that the real-time K1VHRR LSA has slight positive impact on rainfall forecast.

Kumar, Prashant; Bhattacharya, Bimal K.; Nigam, Rahul; Kishtawal, C. M.; Pal, P. K.

2014-03-01

285

Surface dynamics of observed maritime fronts  

NASA Technical Reports Server (NTRS)

The importance of various dynamical processes in the surface fronts over the ocean is investigated using the unique data set supplied by the Seasat-A satellite scatterometer, in conjunction with a planetary boundary layer model. The governing equations are presented, and a similarity model that includes the effects of shear and the effects of shear and deformation on an Ekman solution is derived. It is shown that surface friction is important in frontal processes through its role in determining the dissipation and the ageostrophic terms in the vorticity and divergence equations; the former normally acts to weaken a front while the latter acts to strengthen it. The magnitude and importance of these terms vary considerably at different stages and with stratification, thermal advection, and the deformation and shear forcing.

Levy, Gad

1989-01-01

286

Integrating Clarus Data in Traffic Signal System Operation: A Survivable Real-Time Weather-Responsive System.  

National Technical Information Service (NTIS)

This report presents a prototype of a secure, dependable, real-time weather-responsive traffic signal system. The prototype executes two tasks: (1) accesses weather information that provides near real-time atmospheric and pavement surface condition observ...

A. Abdel-Rahim A. Krings M. Dixon

2011-01-01

287

Coastal Observations of Weather Features in Senegal during the AMMA SOP-3 Period  

NASA Technical Reports Server (NTRS)

During 15 August through 30 September 2006, ground and aircraft measurements were obtained from a multi-national group of students and scientists in Senegal. Key measurements were aimed at investigating and understanding precipitation processes, thermodynamic and dynamic environmental conditions, cloud, aerosol and microphysical processes and spaceborne sensors (TRMM, CloudSat/Calipso) validation. Ground and aircraft instruments include: ground based polarimetric radar, disdrometer measurements, a course and a high-density rain gauge network, surface chemical measurements, a 10 m flux tower, broadband IR, solar and microwave measurements, rawinsonde and radiosonde measurements, FA-20 dropsonde, in situ microphysics and cloud radar measurements. Highlights during SOP3 include ground and aircraft measurements of squall lines, African Easterly Waves (AEWs), Saharan Air Layer advances into Senegal, and aircraft measurements of AEWs -- including the perturbation that became Hurricane Isaac.

Jenkins, G.; Kucera, P.; Joseph, E.; Fuentes, J.; Gaye, A.; Gerlach, J.; Roux, F.; Viltard, N.; Papazzoni, M.; Protat, A.; Bouniol, D.; Reynolds, A.; Arnault, J.; Badiane, D.; Kebe, F.; Camara, M.; Sall, S.

2009-01-01

288

Space Weathering of Rocks  

NASA Technical Reports Server (NTRS)

Space weathering discussions have generally centered around soils but exposed rocks will also incur the effects of weathering. On the Moon, rocks make up only a very small percentage of the exposed surface and areas where rocks are exposed, like central peaks, are often among the least space weathered regions we find in remote sensing data. However, our studies of weathered Ap 17 rocks 76015 and 76237 show that significant amounts of weathering products can build up on rock surfaces. Because rocks have much longer surface lifetimes than an individual soil grain, and thus record a longer history of exposure, we can study these products to gain a deeper perspective on the weathering process and better assess the relative impo!1ance of various weathering components on the Moon. In contrast to the lunar case, on small asteroids, like Itokowa, rocks make up a large fraction of the exposed surface. Results from the Hayabusa spacecraft at Itokowa suggest that while the low gravity does not allow for the development of a mature regolith, weathering patinas can and do develop on rock surfaces, in fact, the rocky surfaces were seen to be darker and appear spectrally more weathered than regions with finer materials. To explore how weathering of asteroidal rocks may differ from lunar, a set of ordinary chondrite meteorites (H, L, and LL) which have been subjected to artificial space weathering by nanopulse laser were examined by TEM. NpFe(sup 0) bearing glasses were ubiquitous in both the naturally-weathered lunar and the artificially-weathered meteorite samples.

Noble, Sarah

2011-01-01

289

Deeply weathered basement rocks in Norway  

NASA Astrophysics Data System (ADS)

Recent studies show that, in addition to tectonic processes, surface processes have also had a profound impact on the topography of Norway. This is especially obvious for the northernmost part of the Nordland county and for western Norway, where the current immature Alpine-type topography cannot be easily explained by tectonic processes only. Erosion of the sedimentary succession also does not seem sufficient to explain the observed relief. Common remnants of deeply weathered basement rocks, however, indicate a history of deep alteration and later erosion of the bedrock, which needs to be considered as another important factor in the development of the topographic relief. Most of the sites with deeply weathered basement exhibit a clay-poor grussy type of weathering, which is generally considered to be of relatively young age (Plio-/Pleistocene) and thought to represent an intermediate stage of weathering. Unfortunately, small amounts or complete absence of clay minerals in these weathering products precluded the accurate dating of this weathered material. Scandinavia was exposed to a large range of glaciations and the once extensive sedimentary successions have been almost entirely eroded, which impedes a minimum age estimate of the weathering profile. Although several sites preserving remnants of deep weathering can still be observed onshore Norway, they are all covered by Quaternary overburden and the age of the regolith remains thus unconstrained and a matter of debate. The only exception is a small Mesozoic basin on Andøya, northern Norway, where weathered and clay-poor saprolite was found underlying Jurassic and Cretaceous sedimentary rocks. Over the last few years the Geological Survey of Norway (NGU) has mapped and investigated deep weathering onshore Norway to better understand weathering processes and to constrain the age of the weathering remnants. The combined interpretation of geophysical, mineralogical and geochemical data, together with recent observations from the Norwegian shelf, where grussy type of weathered bedrock was found buried under Mesozoic sediments, leads to the conclusion that coarse-grained, clay-poor saprolite does not necessarily indicate a young age of weathering but could in fact be of Early Mesozoic age or even older. The Late Jurassic to Early Cretaceous faults in the Lofoten-Vesterålen area are for instance little affected by weathering processes. With the goal to refine our understanding of the complex weathering processes and to constrain them in time, the NGU is establishing a new K-Ar laboratory for the dating and characterization of illite grown authigenically in the saprolites. It is expected that the data generated therein will contribute new quantitative constraints to the long-lasting debate as to the age of weathering processes in Scandinavia.

Bönner, Marco; Knies, Jochen; Fredin, Ola; Olesen, Odleiv; Viola, Giulio

2014-05-01

290

On the Relationship Between the Effects of Targeted Weather Observations and Local Low Dimensionalities in the Atmosphere  

NASA Astrophysics Data System (ADS)

Recently, the concept of targeting weather observations has been tested by idealized model experiments and by deploying dropsonde observations from aircraft in Northern Hemisphere winter field programs. While the evaluation studies have so far provided convincing empirical evidence that targeting observations is an operationally attainable way to improve forecasts, the exact dynamical mechanisms through which targeted observations realize their beneficial forecast effects have not yet been explored. The main differences between the targeting strategies proposed by the different teams are in the algorithms used to select to locations of the added observations. Nevertheless, there is one common element of these techniques; they are all linear inferences applied to a set of numerical forecasts. The main goal of this paper is to investigate why methods based on such a strong assumption can have skill in determining the optimal locations of the added observations. It will be argued that regions of local low dimensionality of the unstable subspace in the atmosphere (Patil et al., 2001) play an important role in the success of targeting. The above goal is achieved by first generating a large experimental ensemble of forecasts using the T62 horizontal resolution version of the operational global model of the National Centers for Environmental Prediction (NCEP). A one month case study associated with the 2000 Winter Reconnaissance Program (Szunyogh et al. 2001) is prepared. Then the regions of local low dimensionality are determined. The relationship between locations of these regions, the local energetics of the baroclinic wave packets, and the propagation of the influence of the added observations is explored. >http://www.math.umd.edu/~dap/chaos_atmos.html

Zimin, A.; Szunyogh, I.; Patil, D.; Kalnay, E.; Yorke, J.; Hunt, B.; Ott, E.

2001-12-01

291

Weather Forecasting  

NSDL National Science Digital Library

This activity is designed to give students an understanding of how to forecast weather and how to use weather reports for their personal benefit. They will be able to tell what weather is, read weather instruments, understand basic cloud formations in relation to the weather, and make forecasts for two days in advance.

292

The large-scale spatio-temporal variability of precipitation over Sweden observed from the weather radar network  

NASA Astrophysics Data System (ADS)

Using measurements from the national network of 12 weather radar stations for the 11-year period 2000-2010, we investigate the large-scale spatio-temporal variability of precipitation over Sweden. These statistics provide useful information to evaluate regional climate models as well as for hydrology and energy applications. A strict quality control is applied to filter out noise and artifacts from the radar data. We focus on investigating four distinct aspects: the diurnal cycle of precipitation and its seasonality, the dominant timescale (diurnal versus seasonal) of variability, precipitation response to different wind directions, and the correlation of precipitation events with the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). When classified based on their intensity, moderate- to high-intensity events (precipitation > 0.34 mm/3 h) peak distinctly during late afternoon over the majority of radar stations in summer and during late night or early morning in winter. Precipitation variability is highest over the southwestern parts of Sweden. It is shown that the high-intensity events (precipitation > 1.7 mm/3 h) are positively correlated with NAO and AO (esp. over northern Sweden), while the low intensity events are negatively correlated (esp. over southeastern parts). It is further observed that southeasterly winds often lead to intense precipitation events over central and northern Sweden, while southwesterly winds contribute most to the total accumulated precipitation for all radar stations. Apart from its operational applications, the present study demonstrates the potential of the weather radar data set for studying climatic features of precipitation over Sweden.

Devasthale, A.; Norin, L.

2014-06-01

293

The large-scale spatio-temporal variability of precipitation over Sweden observed from the weather radar network  

NASA Astrophysics Data System (ADS)

Using measurements from the national network of 12 weather radar stations for the last decade (2000-2010), we investigate the large-scale spatio-temporal variability of precipitation over Sweden. These statistics provide useful information to evaluate regional climate models as well as for hydrology and energy applications. A strict quality control is applied to filter out noise and artifacts from the radar data. We focus on investigating four distinct aspects namely, the diurnal cycle of precipitation and its seasonality, the dominant time scale (diurnal vs. seasonal) of variability, precipitation response to different wind directions, and the correlation of precipitation events with the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). When classified based on their intensity, moderate to high intensity events (precipitation > 0.34 mm (3 h)-1) peak distinctly during late afternoon over the majority of radar stations in summer and during late night or early morning in winter. Precipitation variability is highest over the southwestern parts of Sweden. It is shown that the high intensity events (precipitation > 1.7mm (3 h)-1) are positively correlated with NAO and AO (esp. over northern Sweden), while the low intensity events are negatively correlated (esp. over southeastern parts). It is further observed that southeasterly winds often lead to intense precipitation events over central and northern Sweden, while southwesterly winds contribute most to the total accumulated precipitation for all radar stations. Apart from its operational applications, the present study demonstrates the potential of the weather radar data set for studying climatic features of precipitation over Sweden.

Devasthale, A.; Norin, L.

2013-12-01

294

The Surface of Titan: Arecibo Radar Observations  

NASA Technical Reports Server (NTRS)

The Arecibo 12.6 cm radar system was used to observe Titan in 1999, 2000 and 2001. The mean value of the radar albedo is 0.16 and the polarization ratio is 0.35. For some longitudes the echo has a specular component although most of the echo power is contained in a diffuse component. Additional information is contained in the original extended abstract.

Campbell, D. B.; Black, G. J.; Carter, L. M.; Hine, A. A.; Margot, J. L.; Nolan, M. C.; Ostro, S. J.

2002-01-01

295

A simple parameterization of the short-wave aerosol optical properties for surface direct and diffuse irradiances assessment in a numerical weather model  

NASA Astrophysics Data System (ADS)

Broadband short-wave (SW) surface direct and diffuse irradiances are not typically within the set of output variables produced by numerical weather prediction (NWP) models. However, they are being more and more demanded in solar energy applications. A detailed representation of the aerosol optical properties is important to achieve an accurate assessment of these direct and diffuse irradiances. Nonetheless, NWP models typically oversimplify its representation or even neglect its effect. In this work, a flexible method to account for the SW aerosol optical properties in the computation of broadband SW surface direct and diffuse irradiances is presented. It only requires aerosol optical depth at 0.55 ?m and the type of predominant aerosol. The rest of parameters needed to consider spectral aerosol extinction, namely, Angström exponent, aerosol single-scattering albedo and aerosol asymmetry factor, are parameterized. The parameterization has been tested in the RRTMG SW scheme of the Weather Research and Forecasting (WRF) NWP model. However, it can be adapted to any other SW radiative transfer band model. It has been verified against a control experiment along five radiometric stations in the contiguous US. The control experiment consisted of a clear-sky evaluation of the RRTMG solar radiation estimates obtained in WRF when RRTMG is driven with ground-observed aerosol optical properties. Overall, the verification has shown very satisfactory results for both broadband SW surface direct and diffuse irradiances. It has proven effective to significantly reduce the prediction error and constraint the seasonal bias in clear-sky conditions to within the typical observational error in well-maintained radiometers.

Ruiz-Arias, J. A.; Dudhia, J.

2014-01-01

296

Observational cross helicity on the solar surface  

NASA Astrophysics Data System (ADS)

We analyzed the correlation of the solar magnetograms and Dopplergrams from SOHO/MDI and SDO/HMI respectively. It is found that the full disk correlation coefficient of Dopplergrams is more than 0.80 between SOHO/MDI and SDO/HMI. The full disk correlation coefficient of magnetograms is about 0.73 and is more than 0.95 for active regions only. We also analyzed the distribution of the cross helicity (velocity-magnetic-field correlation) on the solar surface. It is found that the latitude distributions of the cross helicity based on SOHO/MDI data and SDO/HMI data have similar tendencies, and in the analysis of solar active regions the amplitude of the horizontal component of the mean cross helicity is about two times the line-of-sight one.

Zhao, MingYu; Wang, XiaoFan; Zhang, HongQi

2014-01-01

297

Weather Watch  

ERIC Educational Resources Information Center

Suggests a number of ways in which Federal Aviation Agency weather report printouts can be used in teaching the weather section of meteorology. These weather sequence reports can be obtained free of charge at most major airports. (JR)

Bratt, Herschell Marvin

1973-01-01

298

Venus NIR Surface Emissivity estimated from VIRTIS on Venus Express Observations  

NASA Astrophysics Data System (ADS)

Spectral window regions close to 1?m allow for the transfer of thermal radiation from the surface through the atmosphere of Venus. Results of radiative transfer modeling are used to invert VIRTIS images at 1.02, 1.10 and 1.18?m for thermal emission of the surface. Local atmospheric transmittance is derived from the VIRTIS band at 1.31?m. Several hundreds of VIRTIS images covering in total most of the southern hemisphere of Venus have thus been analyzed and stacked for improvement of signal to noise ratio. The results of this approach are to some extent ambiguous since neither surface emissivity nor surface temperature are well known. Furthermore aerosols or a gradient of absorbing gaseous constituents near the surface might affect the interpretation. But neglecting any effects of the near surface atmosphere and assuming parameters of the radiative transfer model within reasonable ranges it is possible to estimate either surface emissivity or surface temperature. Temperature of surface and atmosphere is mostly a function of altitude, no large diurnal, seasonal or latitudinal variations are expected in the lower atmosphere. The lapse rate is constrained by the adiabatic lapse rate. A hint for global average of surface emissivity is given by the dominance of probably basaltic volcanic plains on the southern hemisphere. It is however imaginable that temperature dependant weathering leads to a trend of emissivity with altitude similar to that seen in the Magellan radiothermal emissivity observations. Regardless of any global variations of lapse rate or emissivity with altitude, spatial variations of emissivity independent from topography can be examined by assuming constant emissivity and fitting surface temperature accordingly to the global relation of thermal emission to topography. This spatial variation of thermal emission is assumed to be due to variation of surface emissivity and shows correlation with some geological features known from Magellan radar images. In the Lada Terra region large lava streams, Cavillaca - and Juturna Fluctus, show increased emissivity with respect to neighboring regions of the same altitude. Other large lava streams in the region show a similar but less obvious relative emissivity. Large areas of tessera terrain on the contrary consistently show relative low emissivity. While this variation of emissivity might be related to content of mafic minerals it is also conceivable that weathering and thus age of the terrain in question is responsible. The accumulation of observations by VIRTIS during the Venus Express mission will allow us to study with a larger database these correlations and to further disentangle possible atmospheric from surface contributions and thus to increase understanding of surface composition as well as of composition and temperature of the atmosphere in contact with the surface.

Mueller, N.; Helbert, J.; Hashimoto, G.; Kostama, P.; Marinangeli, L.; Erard, S.; Piccioni, G.; Drossart, P.; Venus Express Team

2007-12-01

299

Observational and theoretical studies of the evolving structure of baroclinic waves: Attractor dynamics of global weather systems  

NASA Technical Reports Server (NTRS)

Significant progress was made in developing a six-component dry model of mid-latitude baroclinic wave evolution, and a ten-component moist model. These models include representations of airflow over mountians and non-adiabatic processes. As a first step, the properties of a reduced, three component, baroclinic system are studied. The classical baroclinic stability criteria emerge as the properties of one of the three equilibria admitted, with the remaining two equilibria forming the attractor region for the observed weather activity. Passive tracer evolution in a baroclinic wave was studied. A model in which only constituents trapped within low atmospheric levels are considered, has been extended to include the possibility for fluxes into the upper levels of the atmosphere. The reported results for the lower levels achieved previously are shown to be qualitatively similar to those obtained by these new calculations in which the vertical flux constraint is removed. An extensive study of an 8-year record of global outgoing longwave radiation for the Northern Hemisphere reveals that blocking events exhibit only a weak signature of blocking highs, as measured by relatively low values of the ratio of the standard deviation to the mean value of the observed long wave outgoing radiation. Though present in many cases, the signature is not a strongly distinctive feature of the blocking episodes.

Saltzman, B.; Hansen, A. R.; Nagle, R. N.; Tang, C. M.

1985-01-01

300

A lagged response to the 11 year solar cycle in observed winter Atlantic/European weather patterns  

NASA Astrophysics Data System (ADS)

surface response to 11 year solar cycle variations is investigated by analyzing the long-term mean sea level pressure and sea surface temperature observations for the period 1870-2010. The analysis reveals a statistically significant 11 year solar signal over Europe, and the North Atlantic provided that the data are lagged by a few years. The delayed signal resembles the positive phase of the North Atlantic Oscillation (NAO) following a solar maximum. The corresponding sea surface temperature response is consistent with this. A similar analysis is performed on long-term climate simulations from a coupled ocean-atmosphere version of the Hadley Centre model that has an extended upper lid so that influences of solar variability via the stratosphere are well resolved. The model reproduces the positive NAO signal over the Atlantic/European sector, but the lag of the surface response is not well reproduced. Possible mechanisms for the lagged nature of the observed response are discussed.

Gray, Lesley J.; Scaife, Adam A.; Mitchell, Daniel M.; Osprey, Scott; Ineson, Sarah; Hardiman, Steven; Butchart, Neal; Knight, Jeff; Sutton, Rowan; Kodera, Kunihiko

2013-12-01

301

The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations  

NASA Astrophysics Data System (ADS)

For several years passive microwave observations have been used to retrieve soil moisture from the Earth's surface. Low frequency observations have the most sensitivity to soil moisture, therefore the modern Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) satellite missions observe the Earth's surface in the L-band frequency. In the past, several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and Windsat have been used to retrieve surface soil moisture using multi-channel observations obtained at higher microwave frequencies. While AMSR-E and Windsat lack an L-band channel, they are able to leverage multi-channel microwave observations to estimate additional land surface parameters. In particular, the availability of Ka-band observations allows AMSR-E and Windsat to obtain surface temperature estimates required for the retrieval of surface soil moisture. In contrast, SMOS and SMAP carry only a single frequency radiometer. Because of this, ancillary - and potentially less accurate - sources of surface temperature information (e.g. re-analysis data from operational weather prediction centers) must be sought to produce surface soil moisture retrievals. Here, two newly-developed, large-scale soil moisture evaluation techniques, the triple collocation (TC) approach and the R value data assimilation approach, are applied to quantify the global-scale impact of replacing Ka-band based surface temperature retrievals with Modern Era Retrospective-analysis for Research and Applications (MERRA) surface temperature predictions on the accuracy of Windsat and AMSR-E surface soil moisture retrievals. Results demonstrate that under sparsely vegetated conditions, the use of Ka-band radiometric land surface temperature leads to better soil moisture anomaly estimates compared to those retrieved using MERRA land surface temperature predictions. However the situation is reversed for highly vegetated conditions where soil moisture anomaly estimates retrieved using MERRA land surface temperature are superior. In addition, the surface temperature phase shifting approach is shown to generally enhance the value of MERRA surface temperature estimates for soil moisture retrieval. Finally, a high degree of consistency is noted between evaluation results produced by the TC and Rvalue soil moisture verification approaches.

Parinussa, R. M.; Holmes, T. R. H.; Crow, W. T.

2011-07-01

302

The need for satellite based observations of global surface waters  

Microsoft Academic Search

River discharge as well as lake and wetland storage of water are critical elements of land surface hydrology, yet they are poorly observed globally and the prospects for improvement from in-situ networks are bleak. Considering this, our NASA Surface Water working group is focused on the following science and applications questions: (1) What are the observational and data assimilation requirements

D. Lettenmaier; D. Alsdorf; C. Vörösmarty; C. Birkett

2003-01-01

303

Locating Potential Biosignatures on Europa from Surface Geology Observations  

Microsoft Academic Search

We evaluated the astrobiological potential of the major classes of geologic units on Europa with respect to possible biosignatures preservation on the basis of surface geology observations. These observations are independent of any formational model and therefore provide an objective, though preliminary, evaluation. The assessment criteria include high mobility of material, surface concentration of non-ice components, relative youth, textural roughness,

Patricio H. Figueredo; Ronald Greeley; Susanne Neuer; Louis Irwin; Dirk Schulze-Makuch

2003-01-01

304

NOAA Daily Weather Maps  

NSDL National Science Digital Library

The charts on this website are the principal charts of the former Weather Bureau publication, "Daily Weather Map." They are the Surface Weather Map, the 500-Millibar Height Contours chart, the Highest and Lowest Temperatures chart, and the Precipitation Areas and Amounts chart. For each day, simple charts are arranged on a single page. These charts are the surface analysis of pressure and fronts, color shading, in ten degree intervals,of maximum and minimum temperature, 500-Millibar height contours, and color shaded 24-hour total precipitation. These charts act as links to their respective Daily Weather Map charts. All charts are derived from the operational weather maps prepared at the National Centers for Environmental Prediction, Hydrometeorological Prediction Center, National Weather Service.

Center, Hydrometeorological P.

2011-01-01

305

Observed near-surface currents under high wind speeds  

NASA Astrophysics Data System (ADS)

From the Surface Velocity Program (SVP) drifter current and QuikSCAT wind data, the relationship between the observed near-surface current vectors and surface wind vectors for the northwestern Pacific Ocean under high winds (20-50 m s-1) are obtained with quantitative estimations of near-surface drift ratio (current speed versus wind speed)r(˜2%) and near-surface drift angle? (˜0°-10° to the right of the winds). These estimations keep unchanged after removing the surface geostrophic component. From the SVP drifter current and daily WindSat wind data, the estimated ris still approximately 2%. Three linear regression equations are obtained between the observed near-surface current speeds and the surface wind stress for the high wind range.

Chang, Y.-C.; Chen, G.-Y.; Tseng, R.-S.; Centurioni, L. R.; Chu, Peter C.

2012-11-01

306

The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations  

NASA Astrophysics Data System (ADS)

For several years passive microwave observations have been used to retrieve soil moisture from the Earth's surface. Low frequency observations have the most sensitivity to soil moisture, therefore the current Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) satellite missions observe the Earth's surface in the L-band frequency. In the past, several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and WindSat have been used to retrieve surface soil moisture using multi-channel observations obtained at higher microwave frequencies. While AMSR-E and WindSat lack an L-band channel, they are able to leverage multi-channel microwave observations to estimate additional land surface parameters. In particular, the availability of Ka-band observations allows AMSR-E and WindSat to obtain coincident surface temperature estimates required for the retrieval of surface soil moisture. In contrast, SMOS and SMAP carry only a single frequency radiometer and therefore lack an instrument suited to estimate the physical temperature of the Earth. Instead, soil moisture algorithms from these new generation satellites rely on ancillary sources of surface temperature (e.g. re-analysis or near real time data from weather prediction centres). A consequence of relying on such ancillary data is the need for temporal and spatial interpolation, which may introduce uncertainties. Here, two newly-developed, large-scale soil moisture evaluation techniques, the triple collocation (TC) approach and the Rvalue data assimilation approach, are applied to quantify the global-scale impact of replacing Ka-band based surface temperature retrievals with Modern Era Retrospective-analysis for Research and Applications (MERRA) surface temperature output on the accuracy of WindSat and AMSR-E based surface soil moisture retrievals. Results demonstrate that under sparsely vegetated conditions, the use of MERRA land surface temperature instead of Ka-band radiometric land surface temperature leads to a relative decrease in skill (on average 9.7%) of soil moisture anomaly estimates. However the situation is reversed for highly vegetated conditions where soil moisture anomaly estimates show a relative increase in skill (on average 13.7%) when using MERRA land surface temperature. In addition, a pre-processing technique to shift phase of the modelled surface temperature is shown to generally enhance the value of MERRA surface temperature estimates for soil moisture retrieval. Finally, a very high correlation (R2 = 0.95) and consistency between the two evaluation techniques lends further credibility to the obtained results.

Parinussa, R. M.; Holmes, T. R. H.; Yilmaz, M. T.; Crow, W. T.

2011-10-01

307

Chapter 9 Weathering of the meade peak phosphatic shale member, phosphoria formation: Observations based on uranium and its decay products  

Microsoft Academic Search

Variably weathered outcrop samples of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation have 5-10% of the contained uranium (U) in a form readily extractable by 0.1 M sodium bicarbonate. Fission track radiography of outcrop samples and other less-weathered channel and core samples indicate that this mobile fraction of U is likely hosted by organic matter, secondary iron

R. A. Zielinski; J. R. Budahn; R. I. Grauch; J. B. Paces; K. R. Simmons

2004-01-01

308

Weather Basics  

NSDL National Science Digital Library

Students are introduced to the basics of the Earth's weather. Concepts include fundamental causes of common weather phenomena such as temperature changes, wind, clouds, rain and snow. The different factors that affect the weather and the instruments that measure weather data are also addressed.

Integrated Teaching And Learning Program

309

Weather Forecasting  

NSDL National Science Digital Library

Students consider how weather forecasting plays an important part in their daily lives. They learn about the history of weather forecasting â from old weather proverbs to modern forecasting equipment â and how improvements in weather technology have saved lives by providing advance warning of natural hazards.

Integrated Teaching And Learning Program

310

Severe Weather  

NSDL National Science Digital Library

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This month's insert, Severe Weather, has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in this poster are hurricanes, flash floods, lightning, and tornadoes.

Forde, Evan B.

2004-04-01

311

Severe Weather  

ERIC Educational Resources Information Center

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This article deals with a poster entitled, "Severe Weather," that has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in…

Forde, Evan B.

2004-01-01

312

Severe Weather  

ERIC Educational Resources Information Center

Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This month's insert, Severe Weather, has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in this poster are hurricanes,…

Forde, Evan B.

2004-01-01

313

Evaluation of Nimbus 7 SMMR sensor with airborne radiometers and surface observations in the Norwegian Sea  

NASA Technical Reports Server (NTRS)

Measurements made by the Nimbus 7 SMMR are compared with near simultaneous observations using the airborne SMMR simulator and with surface observations. The area of the test is in the Norwegian Sea between Bear Island and Northern Norway. It is noted that during the observation period two low-pressure systems were located in the test area, giving a spatial wind variation from 3-20 m/s. It is shown that the use of the currently available brightness temperatures and algorithms for SMMR does not give universally satisfactory results for SST and wind speed under extreme weather conditions. In addition, the SMMR simulator results are seen as indicating the need for more work on calibration.

Gloersen, P.; Cavalieri, D.; Crawford, J.; Campbell, W. J.; Farrelly, B.; Johannessen, J.; Johannessen, O. M.; Svendsen, E.; Kloster, K.

1981-01-01

314

Severe Weather  

NSDL National Science Digital Library

Meteorologists disagree as to what constitutes severe weather. However, most concur that thunderstorms, tornadoes, and hurricanes, all considered to be "convective" weather, fit the definition of severe weather, which is a weather condition likely to cause hardship. This science guide will explore each of the three weather phenomena. By virtue of their locations, most students are familiar with at least one of the three severe weather events. Students who tour the web sites will have an opportunity to make connections between the familiar and the perhaps less understood weather events.

National Science Teachers Association (NSTA)

2005-04-01

315

Modelling Glacier Surface Temperature Using Weather Station Data and Historical Climate Reconstructions  

Microsoft Academic Search

Models of glacier response to climate change and snow\\/ice melt require knowledge of air temperatures at the glacier surface. This can be directly measured at selected locations, but distributed models of glacier melt require temperature information over an entire surface. Furthermore, in many practical applications, temperature must be estimated for locations where no data is available. A new and more

N. Schaffer; S. J. Marshall

2009-01-01

316

Effect of Contrail Cirrus on Surface Weather Conditions in the Midwest - Phase II.  

National Technical Information Service (NTIS)

The second phase of a study of the effect of aircraft contrails on surface climate in the Upper Midwest had four objectives: To determine the frequency and areal extent of contrail cirrus and their effect on surface temperature, insolation, and other clim...

W. M. Wendland R. G. Semonin

1982-01-01

317

External Resource: Erosion and Weathering  

NSDL National Science Digital Library

This is a Teachers' Domain photo essay with images that depict surface features on Earth that result from weathering and erosion, as well as measures designed to mitigate their unwanted effects. Topics: weathering, erosion, sediments, dunes, deltas, glaci

1900-01-01

318

Space Weathering of Lunar Rocks  

NASA Technical Reports Server (NTRS)

All materials exposed at the lunar surface undergo space weathering processes. On the Moon, boulders make up only a small percentage of the exposed surface, and areas where such rocks are exposed, like central peaks, are often among the least space weathered regions identified from remote sensing data. Yet space weathered surfaces (patina) are relatively common on returned rock samples, some of which directly sample the surface of larger boulders. Because, as witness plates to lunar space weathering, rocks and boulders experience longer exposure times compared to lunar soil grains, they allow us to develop a deeper perspective on the relative importance of various weathering processes as a function of time.

Noble, S. K.; Keller, L. P.; Christoffersen, R.; Rahman, Z.

2012-01-01

319

Winter Weather  

NSDL National Science Digital Library

This project explores factors that help create severe winter weather. An interactive simulation provides hands-on experience, followed by guiding questions and resource exploration. Weather affects our everyday lives. Some days it's sunny and some days its not. The years weather is split up into seasons. 1. What are the four seasons? 2. What kind of weather do you see in the summer? 3. What kind of weather is unique to winter? 4. ...

Bellows, Mrs.

2009-09-28

320

NPP VIIRS Land Surface Temperature EDR validation using NOAA's observation networks  

NASA Astrophysics Data System (ADS)

NOAA will soon use the new Visible Infrared Imager Radiometer Suite (VIIRS) on the Joint Polar Satellite System (JPSS) as its primary polar-orbiting satellite imager. Employing a near real-time processing system, NOAA will generate a series of Environmental Data Records (EDRs) from VIIRS data. For example, the VIIRS Land Surface Temperature (LST) EDR will estimate the surface skin temperature over all global land areas and provide key information for monitoring Earth surface energy and water fluxes. Because both VIIRS and its processing algorithms are new, NOAA is conducting a rigorous calibration and validation program to understand and improve product quality. This work presents a new validation methodology to estimate the quantitative uncertainty in the LST EDR, and contribute to improving the retrieval algorithm. It employs a physically-based approach to scaling up point LST measurements currently made operationally at many field and weather stations around the world. The scaling method consists of the merging information collected at different spatial resolutions within a land surface model to fully characterize large area (km x km scale) satellite products. The approach can be used to explore scaling issues over terrestrial surfaces spanning a large range of climate regimes and land cover types, including forests and mixed vegetated areas. First results show that VIIRS and MODIS (collection 5) LST products are very consistent. Over vegetated areas, VIIRS LST EDRs verify JPSS program quality requirements - bias and precision specifications of VIIRS LST EDRs are 1.5K and 2.5K. However, VIIRS agrees better with scaled-up field data than with non-scaled field observations. Over desert areas, current VIIRS LST EDRs do not verify JPSS specifications. VIIRS and MODIS LST products tend to underestimate surface temperature at night. Ultimately, this validation approach should lead to an accurate and continuously-assessed VIIRS LST products suitable to support weather forecast, hydrological applications, or climate studies. It is readily adaptable to other moderate resolution satellite systems.

Guillevic, P. C.; Privette, J. L.

2012-12-01

321

Correction of Sampling Errors in Ocean Surface Cross-Sectional Estimates from Nadir-Looking Weather Radar  

NASA Technical Reports Server (NTRS)

The return from the ocean surface has a number of uses for airborne meteorological radar. The normalized surface cross section has been used for radar system calibration, estimation of surface winds, and in algorithms for estimating the path-integrated attenuation in rain. However, meteorological radars are normally optimized for observation of distributed targets that fill the resolution volume, and so a point target such as the surface can be poorly sampled, particularly at near-nadir look angles. Sampling the nadir surface return at an insufficient rate results in a negative bias of the estimated cross section. This error is found to be as large as 4 dB using observations from a high-altitude airborne radar. An algorithm for mitigating the error is developed that is based upon the shape of the surface echo and uses the returned signal at the three range gates nearest the peak surface echo.

Caylor, I. Jeff; Meneghini, R.; Miller, L. S.; Heymsfield, G. M.

1997-01-01

322

Site characterization summary report for dry weather surface water sampling upper East Fork Poplar Creek characterization area Oak Ridge Y-12 Plant, Oak Ridge, Tennessee  

SciTech Connect

This report describes activities associated with conducting dry weather surface water sampling of Upper East Fork Poplar Creek (UEFPC) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. This activity is a portion of the work to be performed at UEFPC Operable Unit (OU) 1 [now known as the UEFPC Characterization Area (CA)], as described in the RCRA Facility Investigation Plan for Group 4 at the Oak- Ridge Y-12 Plant, Oak Ridge, Tennessee and in the Response to Comments and Recommendations on RCRA Facility Investigation Plan for Group 4 at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, Volume 1, Operable Unit 1. Because these documents contained sensitive information, they were labeled as unclassified controlled nuclear information and as such are not readily available for public review. To address this issue the U.S. Department of Energy (DOE) published an unclassified, nonsensitive version of the initial plan, text and appendixes, of this Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) Plan in early 1994. These documents describe a program for collecting four rounds of wet weather and dry weather surface water samples and one round of sediment samples from UEFPC. They provide the strategy for the overall sample collection program including dry weather sampling, wet weather sampling, and sediment sampling. Figure 1.1 is a schematic flowchart of the overall sampling strategy and other associated activities. A Quality Assurance Project Plan (QAPJP) was prepared to specifically address four rounds of dry weather surface water sampling and one round of sediment sampling. For a variety of reasons, sediment sampling has not been conducted and has been deferred to the UEFPC CA Remedial Investigation (RI), as has wet weather sampling.

NONE

1996-08-01

323

Mountain Weather  

NSDL National Science Digital Library

Mountains can be awe-inspiring both for the vistas they provide and for the weather events and long-term climate systems they support. This interactive feature illustrates how a moisture-laden air mass interacts with a mountain slope to produce characteristic patterns of precipitation over the mountain and surrounding areas. Viewers can see how clouds and precipitation form as the air mass ascends the windward side of the peak, and observe the rain shadow created on the leeward side by the descending, warmed, and moisture-depleted air. A background essay and list of discussion questions supplement the interactive feature.

324

Weather Photography  

NSDL National Science Digital Library

Ph.D. student Harald Edens describes himself as a "photographer of lightning, clouds, atmospheric optical phenomena and astronomy". His Web site entitled Weather Photography proves this by providing a stunning collection of photographs and movies of atmospheric optics, lightning, clouds, and astronomy. The author describes how the photographs were taken, what equipment was used, and even discusses many of the phenomenon being observed such as mirages and halos. An added bonus of this very interesting site is that the author generously allows free personal use of the photographs.

2000-01-01

325

How Do Meteorologists Forecast the Weather?  

NSDL National Science Digital Library

This is a lesson that I developed where students learn how meteorologists predict the weather. Students will use surface weather maps, radar, satellite, and weather models from the National Weather Service to assess the current state of the weather and make a prediction.

Faysash, David

2012-07-30

326

Correlation between ground weather radar and satellite observations at microwaves for the Grímsvötn volcanic eruption on May 2011  

NASA Astrophysics Data System (ADS)

The potential use of passive and active microwaves sensors to provide quantitative information about near-source volcanic ash cloud parameters during an eruptive event is analyzed in this work from an experimental point of view. To this aim ground-based microwave (MW) weather radar and satellite MW radiometer observations are used together. The target area where the collected measurements are compared is the Icelandic subglacial volcanic region and the analyzed case study is that of the Grímsvötn eruption on May 2011. The analyzed weather radar data include those of the Keflavík (Iceland) site (260 km far from the volcano vent) operating at single polarization and working at the frequency of 5.6 GHz with a range resolution of 2 km and that of a portable radar system positioned 70 km far from the volcano vent with polarimetry capabilities (i.e. able to measure signals from both the orthogonal polarizations of the backscattered power as well as the phase shift returns) and working at the frequency of 10 GHz with a range spatial resolution of 0.25 km. On the other hand, the measurements from the satellite passive radiometer are derived from the Special Sensor Microwave Imager/Sounder (SSMIS) in terms of brightness temperature. SSMIS is a conically scanning passive microwave radiometer aboard of a low-earth- orbit platform with several channels (from about 19 GHz to 189 GHz) and with a ground resolution variable from 12.5 and 25 km depending from the frequency channel used. The diversity in terms of spatial scale, frequency, polarization and observation point of view of the collected data gives an original contribution to the characterization of the near source parameters of the Grímsvötn eruption in May 2011 highlighting the advantages and drawbacks of microwave sensors used for volcanic purposes. Traditionally, the monitoring of ash plumes is performed exploiting thermal infrared (TIR) and optical channels of spaceborne radiometers. These measurements can be obtained from sensors aboard geosynchronous-earth-orbit (GEO) and low-earth- orbit (LEO) satellites, thus offering different spatial and temporal resolutions for ash cloud remote sensing. For GEO platforms the advantage of rapid sampling of the earth scene is paid with lower resolution (typically larger than few kilometers), whereas for LEO the revisit time may be even longer than 12 hours. Moreover, TIR and optical channels may suffer from strong ash cloud opacity (very often mixed with water cloud) due to the significant radiation extinction especially in the proximity of the volcanic source. In this respect, the exploitation of the microwave (MW) passive sensors may represent a good opportunity due to their capability to sound the ash cloud, though with some inherent limitations. The results of this work will be shown in terms of correlation between the passive satellite-based brightness temperatures and active ground based retrievals of ash content. The latter is obtained applying the Volcanic Ash Radar Retrieval (VARR) technique both on single and dual polarization mode. The advantage of using the ground based radar orthogonal-polarization measurements will be preliminarily discussed.

Montopoli, Mario; Cimini, Domenico; Vulpiani, Gianfranco; Marzano, Frank S.

2013-04-01

327

Progress in Space Weather Modeling and Observations Needed to Improve the Operational NAIRAS Model Aircraft Radiation Exposure Predictions  

NASA Astrophysics Data System (ADS)

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. During the development of the NAIRAS model, new science questions were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. Addressing these science questions require improvements in both space weather modeling and observations. The focus of this talk is to present these science questions, the proposed methodologies for addressing these science questions, and the anticipated improvements to the operational predictions of atmospheric radiation exposure. The overarching goal of this work is to provide a decision support tool for the aviation industry that will enable an optimal balance to be achieved between minimizing health risks to passengers and aircrew while simultaneously minimizing costs to the airline companies.

Mertens, C. J.; Kress, B. T.; Wiltberger, M. J.; Tobiska, W.; Xu, X.

2011-12-01

328

Transpose AMIP: a process oriented climate model evaluation and intercomparison using model weather forecasts and field campaign observations  

NASA Astrophysics Data System (ADS)

Transpose AMIP is a WGNE intercomparison of weather forecasts made by climate models, with the goal of exposing parameterization errors. The approach allows direct comparison of parameterized variables such as clouds, precipitation, and radiative flues with observations from field programs. During the early period of the forecasts, the parameterization calculations are based on a resolved model state which is close to the observed atmosphere instead of one which is in a model balance. Thus the parameterization errors can be identified. We compare global models from the the Numerical Prediction Division, Japan Meteorological Agency; the National Center for Atmospheric Research; the Geophysical Fluid Dynamics Laboratory; the Experimental Climate Prediction Center, Scripps Institute of Oceanography; and the Climate Model Development and Evaluation group of the Met Office Hadley Centre. We consider the parameterization behaviors in the atmospheric column at the ARM Southern Great Plains site during summer 1997 and spring 2000 IOPs for five-day forecasts initialized from ERA-40 data. ARM observations and the ARM variational analysis are used for verification. We will show that the models exhibit a wide range of behaviors in the parameterization tendencies, which lead to different dynamical responses, balances, and errors. In summer, some models dry the lower troposphere compared to ARM data while others moisten it, and still others produce only modest changes. However, those modest changes arise from a balance between parameterization and dynamical tendency errors as calculated against the ARM estimates. One model shows large 0-24 hour parameterization errors which produce an erroneous state after 1 day. However, for days 2-5 the parameterization errors are relatively small, and the state errors remain relatively unchanged from the day 1 values. The parameterizations produce the correct forcing after day 1 but they calculate it from the wrong state. We speculate that this is a result of tuning for the climate. In contrast, other models show relatively constant state errors from day 1 to day 3, with the parameterization and dynamics errors balancing after day 1 to yield relatively constant state errors. The 0-24 hr rainfall varies greatly between models, one rains heavily almost every day, another rains very little, and still another is in between and captures the episodic nature of the rain fairly well. However, for each model the 24-48 hr rainfall is very different from the 0-24 hour values. This arises because after day one the model states no longer match the atmosphere. Other aspects of the development of the errors will be discussed, in particular the diurnal phasing of the errors, and the response of the dynamics to the parameterizations.

Williamson, D.; Nakagawa, M.; Klein, S.; Earnshaw, P.; Nunes, A.; Roads, J.

2009-04-01

329

Observation of surface roughness at the interface by neutron reflectometry  

NASA Astrophysics Data System (ADS)

The surface roughness of Fe-blocks, manufactured by mechanical grinding, has been observed by neutron reflectometry in air and at the interface with a Si-block. A reflectometer, MINE, at JRR-3 in JAEA was used. Fe-blocks having various types of surface roughness were prepared with roughnesses, Rmax of 0.1-0.8 ?m. The beam distribution observed by an imaging plate (IP) was compared with the intensity distribution estimated from the surface roughness measured by a contact-type roughness gauge. The intensity distribution observed on the IP agrees well with the calculated intensity distribution and becomes more dispersive with increasing roughness. Neutron reflectometry was found to be very useful for observing the mechanical surface roughness with an accuracy of 0.1 ?m, especially at the solid-solid interface.

Inoue, Kazuko; Hirayama, Tomoko; Ebisawa, Toru; Tasaki, Seiji; Hino, Masahiro

2006-11-01

330

Backyard Weather Stations  

NSDL National Science Digital Library

Learn how to build your own backyard weather station with complete directions provided by FamilyEducation.com's Web site, Backyard Weather Stations. The site shows exactly what you'll need and how to build the necessary components (e.g., rain gauge and barometer), as well as how to keep records of the data collected. Parents and teachers will enjoy watching the kids "learn the basics of scientific observation and record-keeping while satisfying their natural curiosity about weather."

Randall, Dennis.

331

Weather and climate  

NASA Technical Reports Server (NTRS)

Recommendations for using space observations of weather and climate to aid in solving earth based problems are given. Special attention was given to: (1) extending useful forecasting capability of space systems, (2) reducing social, economic, and human losses caused by weather, (3) development of space system capability to manage and control air pollutant concentrations, and (4) establish mechanisms for the national examination of deliberate and inadvertent means for modifying weather and climate.

1975-01-01

332

Validation of General Circulation Model Radiative Fluxes Using Surface Observations  

Microsoft Academic Search

The surface radiative fluxes of the ECHAM3 General Circulation Model (GCM) with T2 1, T42, and T 106 resolutions have been validated using observations from the Global Energy Balance Archive (GEBA, World Climate Program-Water Project A7). GEBA contains the most comprehensive dataset now available for worldwide instrumentally measured surface energy fluxes.The GCM incoming shortwave radiation at the surface has been

Martin Wild; Atsumu Ohmura; Hans Gilgen; Erich Roeckner

1995-01-01

333

Validation of general circulation model radiative fluxes using surface observations  

Microsoft Academic Search

The surface radiative fluxes of the ECHAM3 General Circulation Model (GCM) with T21, T42, and T106 resolutions have been validated using observations from the Global Energy Balance Archive (GEBA, World Climate Program-Water Project A7). GEBA contains the most comprehensive dataset now available for worldwide instrumentally measured surface energy fluxes. The GCM incoming shortwave radiation at the surface has been compared

M. Wild; A. Oshmura; H. Gilgen

1995-01-01

334

Characterisation of pollutants washed off from road surfaces during wet weather  

Microsoft Academic Search

This paper presents the results of a monitoring programme carried out to study the washoff of various pollutants from impermeable road surfaces by the runoff produced under artificial and real rainfall conditions. Among the pollution parameters analysed are solids (total, suspended and total volatile), COD (chemical oxygen demand), ammonium and heavy metals (lead, copper, zinc and iron). Analysis of the

F. A. Memon; D. Butler

2005-01-01

335

Low Cloud Type over the Ocean from Surface Observations. Part III: Relationship to Vertical Motion and the Regional Surface Synoptic Environment.  

NASA Astrophysics Data System (ADS)

Composite large-scale dynamical fields contemporaneous with low cloud types observed at midlatitude Ocean Weather Station (OWS) C and eastern subtropical OWS N are used to establish representative relationships between low cloud type and the synoptic environment. The composites are constructed by averaging meteorological observations of surface wind and sea level pressure from volunteering observing ships (VOS) and analyses of sea level pressure, 1000-mb wind, and 700-mb pressure vertical velocity from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis project on those dates and times of day when a particular low cloud type was reported at the OWS.VOS and NCEP results for OWS C during summer show that bad-weather stratus occurs with strong convergence and ascent slightly ahead of a surface low center and trough. Cumulus-under-stratocumulus and moderate and large cumulus occur with divergence and subsidence in the cold sector of an extratropical cyclone. Both sky-obscuring fog and no-low-cloud typically occur with southwesterly flow from regions of warmer sea surface temperature and differ primarily according to slight surface convergence and stronger warm advection in the case of sky-obscuring fog or surface divergence and weaker warm advection in the case of no-low-cloud. Fair-weather stratus and ordinary stratocumulus are associated with a mixture of meteorological conditions, but differ with respect to vertical motion in the environment. Fair-weather stratus occurs most commonly in the presence of slight convergence and ascent, while stratocumulus often occurs in the presence of divergence and subsidence.Surface divergence and estimated subsidence at the top of the boundary layer are calculated from VOS observations. At both OWS C and OWS N during summer and winter these values are large for ordinary stratocumulus, less for cumulus-under-stratocumulus, and least (and sometimes slightly negative) for moderate and large cumulus. Subsidence interpolated from NCEP analyses to the top of the boundary layer does not exhibit such variation, but the discrepancy may be due to deficiencies in the analysis procedure or the boundary layer parameterization of the NCEP model. The VOS results suggest that decreasing divergence and subsidence in addition to increasing sea surface temperature may promote the transition from stratocumulus to trade cumulus observed over low-latitude oceans.

Norris, Joel R.; Klein, Stephen A.

2000-01-01

336

SEM and TEM Observation of the Surfaces of the Fine-Grained Particles Retrieved from the Muses-C Regio on the Asteroid 25413 Itokawa  

NASA Technical Reports Server (NTRS)

Surface materials on airless solar system bodies exposed to interplanetary space are gradually changed their visible to near-infrared reflectance spectra by the process called "space weathering", which makes the spectra darker and redder. Hapke et al. proposed a model of space weathering: vapor deposition of nanophase reduced iron (npFe(sup 0)) on the surfaces of the grains within the very surface of lunar regolith. This model has been proved by detailed observation of the surfaces of the lunar soil grains by transmission electron microscope (TEM). They demonstrated that npFe(sup 0) was formed by a combination of vapor deposition and irradiation effects. In other words, both micrometeorite impacts and irradiation by solar wind and galactic cosmic ray play roles on the space weathering on the Moon. Because there is a continuum of reflectance spectra from those of Q-type asteroids (almost the same as those of ordinary chondrites) to those of S-type asteroids, it is strongly suggested that reflectance spectra of asteroids composed of ordinary chondrite-like materials were modified over time to those of S-type asteroids due to space weathering. It is predicted that a small amount of npFe(sup 0) on the surface of grains in the asteroidal regolith composed of ordinary chondrite-like materials is the main agent of asteroidal space weathering.

Noguchi, T.; Nakamura, T.; Zolensky, Michael E.; Tanaka, M.; Hashimoto, T.; Konno, M.; Nakato, A.; Ogami, T.; Fujimura, A.; Abe, M.; Yada, T.; Mukai, T.; Ueno, M.; Okada, T.; Shirai, K.; Ishibashi, Y.; Okazaki, R.

2011-01-01

337

Ground Effects of Space Weather  

Microsoft Academic Search

Space storms produce geomagnetically induced currents (GIC) in technological systems at the Earth’s surface, such as electric\\u000a power transmission grids, pipelines, communication cables and railways. Thus GIC are the ground end of the space weather chain\\u000a originating from the Sun. The first GIC observations were already made in early telegraph equipment about 150 years ago, and\\u000a since then several different

Risto Pirjola; Ari Viljanen; Antti Pulkkinen; Sami Kilpua; Olaf Amm

338

Chemical weathering and related controls on surface water chemistry in the Absaroka Mountains, Wyoming  

Microsoft Academic Search

Chemical relationships among surface waters, soils and rocks were investigated in the drainage basin of the North Fork of the Shoshone River in northwestern Wyoming. The area is underlain entirely by andesitic volcanic rocks. Smectite is the only clay mineral forming in soils over much of the area, although minor kaolinite occurs in a few areas of higher-than-average rainfall. Mass-balance

William R. Miller; James I. Drever

1977-01-01

339

U. S. Naval Weather Service Command Summary of Synoptic Meteorological Observations: East African and Selected Island Coastal Marine Areas. Volume 4. Area 19 - Kenya Coast, Area 20 - Zanzibar, Area 21 - Tanzania Coast S E, Area 22 - Porto Amelia, Area 23 - Lumbo, Area 24 - Mozambique Channel N W., Area 25 - Mozambique Channel S. W.  

National Technical Information Service (NTIS)

The data contained in these tables were obtained from tape data Family 11 (TDF-11), Marine Surface observations. TDF-11 was primarily funded by the Naval Weather Service Command and selected by NWSED Asheville as the most comprehensive collection of marin...

1974-01-01

340

U.S. Naval Weather Service Command Summary of Synoptic Meteorological Observations - Western European Coastal Marine Areas. Volume 8. Area 44-Iceland SE, Area 45-Reykjavik, Area 46-Iceland NW, Area 47-Iceland N, Area 48-Iceland NE, Area 49-Angmagssalik, Area 50-Cape Farewell SE.  

National Technical Information Service (NTIS)

The data contained in these tables were obtained from tape data family 11 (TDF 11) marine surface observations. TDF-11 was primarily funded by the Naval Weather Service Command and selected by NWSED Asheville as the most comprehensive collection of marine...

1974-01-01

341

An estimation of snow accumulation on Svalbard glaciers on the basis of standard weather-station observations  

Microsoft Academic Search

Winter precipitation in the form of snow is the major factor determining accumulation on Arctic glaciers. In this paper, I present a simple method to assess snow accumulation on the glaciers of Svalbard. I deduce snow accumulation from the sum of winter precipitation and the fraction of precipitation of different types at a reference weather station. The accumulation is then

Mariusz Grabiec

2005-01-01

342

A Dozen Years of Temperature Observations at the Summit: Central Greenland Automatic Weather Stations 1987-99  

Microsoft Academic Search

On 4 May 1987, the first automatic weather station (AWS) near the summit of the Greenland Ice Sheet began transmitting data. Air temperature records from this site, AWS Cathy, as well as nearby AWS at the Greenland Ice Sheet Project II (GISP2, now Summit) camp have been combined with Special Sensor Microwave Imager brightness temperature data to create a composite

Christopher A. Shuman; Konrad Steffen; Jason E. Box; Charles R. Stearns

2001-01-01

343

Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations  

Microsoft Academic Search

Historic sandstone structures carry an inheritance, or a `memory', of past stresses that the stone has undergone since its placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling) and, superimposed upon these, less frequent

S. McCabe; B. J. Smith; P. A. Warke

2007-01-01

344

Space weather effects on midlatitude HF propagation paths: Observations and a data-driven D region model  

Microsoft Academic Search

A two-pronged study is under way to improve understanding of the D region response to space weather and its effects on HF propagation. One part, the HF Investigation of D region Ionospheric Variation Experiment (HIDIVE), is designed to obtain simultaneous, quantitative propagation and absorption data from an HF signal monitoring network along with solar X-ray flux from the NOAA GOES

J. V. Eccles; R. D. Hunsucker; D. Rice; J. J. Sojka

2005-01-01

345

Studying geoeffective interplanetary coronal mass ejections between the Sun and Earth: Space weather implications of Solar Mass Ejection Imager observations  

Microsoft Academic Search

Interplanetary coronal mass ejections (ICMEs) are the primary cause of severe space weather at Earth because they drive shocks and trigger geomagnetic storms that can damage spacecraft and ground-based systems. The Solar Mass Ejection Imager (SMEI) is a U. S. Air Force experiment with the ability to track ICMEs in white light from near the Sun to Earth and beyond,

D. F. Webb; T. A. Howard; C. D. Fry; T. A. Kuchar; D. R. Mizuno; J. C. Johnston; B. V. Jackson

2009-01-01

346

First Observation of Surface Plasmon-Coupled Chemiluminescence (SPCC)  

PubMed Central

In this letter, we report the first observation of surface plasmon-coupled chemiluminescence (SPCC), where the luminescence from chemically induced electronic excited states couples to surface plasmons in a thin continuous silver film. The SPCC is highly directional and predominantly p-polarized, strongly suggesting that the emission is from surface plasmons instead of the luminophores directly themselves. This indicates that surface plasmons can be directly excited from chemically induced excited states. With a wealth of assays that employ chemiluminescence based detection currently in use, then our findings suggest new chemiluminescence sensing strategies based on localized, directional and polarized chemiluminescence detection.

Chowdhury, Mustafa H.; Malyn, Stuart N.; Aslan, Kadir; Lakowicz, Joseph R.; Geddes, Chris D.

2007-01-01

347

Contrail Frequency over the United States from Surface Observations  

Microsoft Academic Search

Contrails have the potential for affecting climate because they impact the radiation budget and the vertical distribution of moisture. Estimating the effect requires additional knowledge about the temporal and spatial variations of contrails. The mean hourly, monthly, and annual frequencies of daytime contrail occurrence are estimated using 2 yr of observations from surface observers at military installations scattered over the

Patrick Minnis; J. Kirk Ayers; Michele L. Nordeen; Steven P. Weaver

2003-01-01

348

Sunspots, Space Weather and Climate  

NASA Astrophysics Data System (ADS)

Four hundred years ago this year the telescope was first used for astronomical observations. Within a year, Galileo in Italy and Harriot in England reported seeing spots on the surface of the Sun. Yet, it took over 230 years of observations before a Swiss amateur astronomer noticed that the sunspots increased and decreased in number over a period of about 11 years. Within 15 years of this discovery of the sunspot cycle astronomers made the first observations of a flare on the surface of the Sun. In the 150 years since that discovery we have learned much about sunspots, the sunspot cycle, and the Sun's explosive events - solar flares, prominence eruptions and coronal mass ejections that usually accompany the sunspots. These events produce what is called Space Weather. The conditions in space are dramatically affected by these events. Space Weather can damage our satellites, harm our astronauts, and affect our lives here on the surface of planet Earth. Long term changes in the sunspot cycle have been linked to changes in our climate as well. In this public lecture I will give an introduction to sunspots, the sunspot cycle, space weather, and the possible impact of solar variability on our climate.

Hathaway, David H.

2009-05-01

349

Weather Forecasting  

NSDL National Science Digital Library

This website, supplied by Annenberg / CPB, discusses weather satellites, Doppler radar, and additional tools forecasters use to predict the weather. Students can find a wind chill calculator along with a brief discussion of the history of forecasting and weather lore. Once you have a firm grasp on the science of weather forecasting, be sure to check out the other sections of this site, which include: "ice and snow," "our changing climate," "the water cycle," and "powerful storms."

2008-03-27

350

Weather Talk  

NSDL National Science Digital Library

Weather Talk is a primer on weather and naval meteorology. It provides a brief overview of major weather elements and is presented in a non-mathematical way, so that the reader will have a better understanding of the basic mechanisms of weather and use it to their advantage and safety in planning and carrying out their own activities. The site explains temperature, wind, pressure, atmospheric moisture, air masses and fronts, thunderstorms, tornadoes, hurricanes, and climatology.

351

Microwave land surface emissivities estimated from SSM\\/I observations  

Microsoft Academic Search

Microwave emissivities of land surfaces are estimated from special sensor microwave\\/imager (SSM\\/I) observations by removing the contributions from the atmosphere, clouds, and rain using ancillary satellite data (International Satellite Cloud Climatology Project (ISCCP) and TIROS Operational Vertical Sounder (TOVS) products). In the first step, cloud-free SSM\\/I observations are isolated with the help of collocated visible\\/infrared satellite observations (ISCCP data). The

Catherine Prigent; William B. Rossow; Elaine Matthews

1997-01-01

352

Undergraduate Earth System Science Education: Project-Based Learning, Land-Atmosphere Interaction, and a Newly Established Student Weather Station  

Microsoft Academic Search

Undergraduate students conducted a semester-long research project as part of a special topics course that launched the Austin College Weather Station in spring 2001. The weather station is located on restored prairie roughly 100 km north of Dallas, Texas. In addition to standard meteorological observations, the Austin College Weather Station measures surface quantities such as soil moisture, soil temperature, solar

D. Baker

2004-01-01

353

Soil, snow, weather, and sub-surface storage data from a mountain catchment in the rain-snow transition zone  

NASA Astrophysics Data System (ADS)

A comprehensive hydroclimatic data set is presented for the 2011 water year to improve understanding of hydrologic processes in the rain-snow transition zone. This type of data set is extremely rare in scientific literature because of the quality and quantity of soil depth, soil texture, soil moisture, and soil temperature data. Standard meteorological and snow cover data for the entire 2011 water year are included, which include several rain-on-snow (ROS) events. Surface soil textures and soil depths from 57 points are presented as well as soil texture profiles from 14 points. Meteorological data include continuous hourly shielded, unshielded, and wind-corrected precipitation, wind speed and direction, air temperature, relative humidity, dew point temperature, and incoming solar and thermal radiation data. This data is often viewed as "forcing data", and is gap filled and serially complete. Sub-surface data included are hourly soil moisture data from multiple depths from seven soil profiles within the catchment, and soil temperatures from multiple depths from two soil profiles. Hydrologic response data include hourly stream discharge from the catchment outlet weir, continuous snow depths from one location, intermittent snow depths from 5 locations, and snow depth and density data from ten weekly snow surveys. Snow and hydrologic response data are meant to provide data on the catchment hydrologic response to the weather data. This data is mostly presented "as measured" although snow depths from one sensor and streamflow at the catchment outlet have been gap filled and are serially complete. Though the weather, snow, and hydrologic response data only covers one water year, the presentation of the additional subsurface data (soil depth, texture, moisture, and temperature) makes it one of the most detailed and complete hydro-climatic data sets from the climatically sensitive rain-snow transition zone. The data presented are appropriate for a wide range of modeling (energy balance snow modeling, soil capacitance parametric modeling, etc.) and descriptive studies. Data is available at doi:10.1594/PANGAEA.819837.

Kormos, P. R.; Marks, D.; Williams, C. J.; Marshall, H. P.; Aishlin, P.; Chandler, D. G.; McNamara, J. P.

2014-04-01

354

Surface Turbulent Fluxes Over Pack Ice Inferred from TOVS Observations  

NASA Technical Reports Server (NTRS)

A one-dimensional, atmospheric boundary layer model is coupled to a thermodynamic ice model to estimate the surface turbulent fluxes over thick sea ice. The principal forcing parameters in this time-dependent model are the air temperature, humidity, and wind speed at a specified level (either at 2 m or at 850 mb) and the downwelling surface radiative fluxes. The free parameters. are the air temperature, humidity, and wind speed profiles below the specified level, the surface skin temperature, the ice temperature profile, and the surface turbulent fluxes. The goal is to determine how well we can estimate the turbulent surface heat and momentum fluxes using forcing parameters from atmospheric temperatures and radiative fluxes retrieved from the TIROS-N Operational Vertical Sounder (TOVS) data. Meteorological observations from the Lead Experiment (LeadEx, April 1992) ice camp are used to validate turbulent fluxes computed with the surface observations and the results are used to compare with estimates based on radio-sonde observations or with estimates based on TOVS data. We find that the TOVS-based estimates of the stress are significantly more accurate than those found with a constant geostrophic drag coefficient, with a root-mean-square error about half as large. This improvement is due to stratification effects included in the boundary layer model. The errors in the sensible heat flux estimates, however, are large compared to the small mean values observed during the field experiment.

Lindsay, R. W.; Francis, J. A.; Persson, P. O. G.; Rothrock, D. A.; Schweiger, A. J.

1996-01-01

355

World Weather  

NSDL National Science Digital Library

What's going on in the world of weather? Are there storms around Sri Lanka? What about the snows of Kilimanjaro? These can be pressing questions, indeed, and the World Weather app is a great way to stay in touch with weather patterns around the globe. Users will find that they can just type in a city name to see the current weather and also zoom around the globe as they see fit. It's a remarkable addition to the world of existing weather tracking apps and is compatible with all operating systems.

Elias, Jaume S.

2014-02-20

356

Weather Watcher  

NSDL National Science Digital Library

As spring progresses, weather conditions can continue to fluctuate dramatically, something that may foil vacation plans or other outings. Keeping that in mind, visitors may do well to download the Weather Watcher application created by Mike Singer. With this application, users may automatically retrieve the current weather conditions, look through hourly forecasts, keep abreast of severe weather alerts, and take a look at weather maps for almost any city world-wide. This application is compatible with all systems running Windows 98 and above.

Singer, Mike

357

Complete Genome Sequence of Dyella jiangningensis Strain SBZ3-12, Isolated from the Surfaces of Weathered Rock.  

PubMed

Dyella jiangningensis strain SBZ3-12 can weather biotite and release Al and Fe from biotite under nutrient-poor conditions. Here, we report the first complete genome sequence of D. jiangningensis strain SBZ3-12, which may facilitate a better understanding of the molecular mechanism behind mineral weathering. PMID:24831147

Bao, Yuanyuan; Kwok, Amy Ho Yan; He, Linyan; Jiang, Jingwei; Huang, Zhi; Leung, Frederick Chi-Ching; Sheng, Xiafang

2014-01-01

358

Complete Genome Sequence of Dyella jiangningensis Strain SBZ3-12, Isolated from the Surfaces of Weathered Rock  

PubMed Central

Dyella jiangningensis strain SBZ3-12 can weather biotite and release Al and Fe from biotite under nutrient-poor conditions. Here, we report the first complete genome sequence of D. jiangningensis strain SBZ3-12, which may facilitate a better understanding of the molecular mechanism behind mineral weathering.

Bao, Yuanyuan; Kwok, Amy Ho Yan; Jiang, Jingwei; Huang, Zhi; Leung, Frederick Chi-ching; Sheng, Xiafang

2014-01-01

359

Weather Scope: An Investigative Study of Weather and Climate  

NSDL National Science Digital Library

During the course of this project, students will learn how to build instruments to measure weather, access online weather observations, collect weather data for an extended period, analyze weather data to reveal trends, and make predictions. They will develop a basic understanding of how weather can be described in measurable quantities such as temperature, wind and precipitation. The module contains five lessons relating to weather, five relating to climate, and three enrichment activities. Project information, a teacher guide, reference materials, and an "ask an expert" feature are also provided.

360

Observations of synoptic-scale land surface variability and its coupling with the atmosphere  

NASA Astrophysics Data System (ADS)

Cloud-free brightness temperatures from satellite are used to interpret changes in the state of the land surface energy balance from day to day across the tropical semi-arid region of North Africa. The method provides an assessment of the spatial and temporal patterns in the surface characteristics. The variability in brightness temperature is closely linked to precipitation, as inferred from available rain-gauge data and satellite cold-cloud imagery. Temperatures drop sharply after rainfall, and increase gradually in subsequent days consistent with surface drying. The analysis shows that surface temperatures (and therefore fluxes) are well-organized at the synoptic scale, and can be linked to the westward propagation of mesoscale convective systems and African easterly waves (AEWs).The modulation of rainfall and cloud cover by weather systems is a key element in producing variability in surface fluxes of heat and moisture. To examine the relationships between surface variability and the atmosphere, a composite of anomalously warm (and dry) surface conditions with spatial coherence over a given longitude band is constructed from satellite data covering a single wet season. Operational analyses are used to examine atmospheric anomalies associated with these composited 'hotspots'. Surface moisture variations on the scale of several hundred km and larger can generate anomalous heat-lows during the day and, according to the operational analyses, generate cyclonic vorticity overnight. These vortices appear to be responsible for the observed modulation of cold cloud in the vicinity of the hotspot, and may influence the characteristics of AEWs in the Northern Sahel. Furthermore, theoretical ideas suggest that surface hotspots are likely to trigger a westward-propagating Rossby-wave response; this process is demonstrated here in a simple numerical model.

Taylor, Christopher M.; Parker, Douglas J.; Lloyd, Colin R.; Thorncroft, Chris D.

2005-04-01

361

The land surface-atmosphere interaction: A review based on observational and global modeling perspectives  

NASA Astrophysics Data System (ADS)

This review discusses the land-surface-atmosphere interaction using observations from two North American field experiments (First International Satellite Land Surface Climatology Project Field Experiment (FIFE) and Boreal Ecosystem Atmosphere Study (BOREAS)) and the application of research data to the improvement of land surface and boundary layer parameterizations in the European Centre for Medium-Range Weather Forecast (ECMWF) global forecast model. Using field data, we discuss some of the diurnal and seasonal feedback loops controlling the net surface radiation and its partition into the surface sensible and latent heat fluxes and the ground heat flux. We consider the impact on the boundary layer evolution and show the changes in the diurnal cycle with soil moisture in midsummer. We contrast the surface energy budget over the tropical oceans with that over both dry and wet land surfaces in summer. Results from a new ECMWF model with four predicted soil layers illustrate the interaction between the soil moisture reservoir, evaporation and precipitation on different timescales and space scales. An analysis of an ensemble of 30-day integrations for July 1993 (the month of the Mississippi flood) showed a large sensitivity of the monthly precipitation pattern (and amount) to different initial soil moisture conditions. Short-range forecasts with old and new land surface and boundary layer schemes showed that the new scheme produced much better precipitation forecasts for the central United States because of a more realistic thermodynamic structure, which in turn resulted from improved evaporation in an area that is about 1-day upstream. The results suggest that some predictability exists in the extended range as a result of the memory of the soil moisture reservoir. We also discuss briefly the problem of soil moisture initialization in a global forecast model and summarize recent experience with nudging of soil moisture at ECMWF and improvements in the surface energy budget coming from the better prediction of clouds.

Betts, Alan K.; Ball, John H.; Beljaars, Anton C. M.; Miller, Martin J.; Viterbo, Pedro A.

1996-03-01

362

Real-Time Weather Data  

NSDL National Science Digital Library

This website provides real-time and forecast weather maps and data for the United States. The Satellite section contains satellite weather images from the GOES 8 and GOES 10 satellites, the Radar section contains radar weather images from NEXRAD radars, the Surface Data section contains plots of various weather conditions (temperatures, winds, pressure, precipitation), and the Upper Air section plots winds and temperatures across the United States.

363

ISCCP Cloud Properties Associated with Standard Cloud Types Identified in Individual Surface Observations  

NASA Technical Reports Server (NTRS)

Individual surface weather observations from land stations and ships are compared with individual cloud retrievals of the International Satellite Cloud Climatology Project (ISCCP), Stage C1, for an 8-year period (1983-1991) to relate cloud optical thicknesses and cloud-top pressures obtained from satellite data to the standard cloud types reported in visual observations from the surface. Each surface report is matched to the corresponding ISCCP-C1 report for the time of observation for the 280x280-km grid-box containing that observation. Classes of the surface reports are identified in which a particular cloud type was reported present, either alone or in combination with other clouds. For each class, cloud amounts from both surface and C1 data, base heights from surface data, and the frequency-distributions of cloud-top pressure (p(sub c) and optical thickness (tau) from C1 data are averaged over 15-degree latitude zones, for land and ocean separately, for 3-month seasons. The frequency distribution of p(sub c) and tau is plotted for each of the surface-defined cloud types occurring both alone and with other clouds. The average cloud-top pressures within a grid-box do not always correspond well with values expected for a reported cloud type, particularly for the higher clouds Ci, Ac, and Cb. In many cases this is because the satellites also detect clouds within the grid-box that are outside the field of view of the surface observer. The highest average cloud tops are found for the most extensive cloud type, Ns, averaging 7 km globally and reaching 9 km in the ITCZ. Ns also has the greatest average retrieved optical thickness, tau approximately equal 20. Cumulonimbus clouds may actually attain far greater heights and depths, but do not fill the grid-box. The tau-p(sub c) distributions show features that distinguish the high, middle, and low clouds reported by the surface observers. However, the distribution patterns for the individual low cloud types (Cu, Sc, St) occurring alone overlap to such an extent that it is not possible to distinguish these cloud types from each other on the basis of tau-p(sub c) values alone. Other cloud types whose tau-p(sub c) distributions are indistinguishable are Cb, Ns, and thick As. However, the tau-p(sub c) distribution patterns for the different low cloud types are nevertheless distinguishable when all occurrences of a low cloud type are included, indicating that the different low types differ in their probabilities of co-occurrence with middle and high clouds.

Hahn, Carole J.; Rossow, William B.; Warren, Stephen G.

1999-01-01

364

Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations  

Microsoft Academic Search

Historic sandstone structures carry an inheritance, or a ‘memory’, of past stresses that the stone has undergone since its\\u000a placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to\\u000a a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling)\\u000a and, superimposed upon these, less frequent

S. McCabe; B. J. Smith; P. A. Warke

2007-01-01

365

Currents in the Taiwan Strait as observed by surface drifters  

Microsoft Academic Search

The trajectories of 110 satellite-tracked surface drifters from 1989 to 2007 were analyzed to elucidate near-surface circulation\\u000a in the Taiwan Strait. Although the summer circulation observed generally agrees with previous studies, several aspects of\\u000a the winter circulation were revealed by the analyses. Unlike many earlier studies, which have suggested that a northward (southward)\\u000a current prevails in the eastern (western) part

Yun QiuLi; Li Li; Chen-Tung Arthur Chen; Xiaogang Guo; Chunsheng Jing

366

Observations During GRIP from HIRAD: Ocean Surface Wind Speed and Rain Rate  

NASA Technical Reports Server (NTRS)

HIRAD (Hurricane Imaging Radiometer) flew on the WB-57 during NASA's GRIP (Genesis and Rapid Intensification Processes) campaign in August - September of 2010. HIRAD is a new C-band radiometer using a synthetic thinned array radiometer (STAR) technology to obtain cross-track resolution of approximately 3 degrees, out to approximately 60 degrees to each side of nadir. By obtaining measurements of emissions at 4, 5, 6, and 6.6 GHz, observations of ocean surface wind speed and rain rate can be inferred. This technique has been used for many years by precursor instruments, including the Stepped Frequency Microwave Radiometer (SFMR), which has been flying on the NOAA and USAF hurricane reconnaissance aircraft for several years. The advantage of HIRAD over SFMR is that HIRAD can observe a +/- 60-degree swath, rather than a single footprint at nadir angle. Results from the flights during the GRIP campaign will be shown, including images of brightness temperatures, wind speed, and rain rate. To the extent possible, comparisons will be made with observations from other instruments on the GRIP campaign, for which HIRAD observations are either directly comparable or are complementary. Potential impacts on operational ocean surface wind analyses and on numerical weather forecasts will also be discussed.

Miller, Timothy L.; James, M. W.; Jones, L.; Ruf, C. S.; Uhlhorn, E. W.; Bailey, M. C.; Buckley, C. D.; Simmons, D. E.; Johnstone, S.; Peterson, A.; Schultz, L. A.; Biewas, S.; Johnson, J. W.; Shah, G.; Feingstein, D.; Cleveland, W. H.; Johnson, J.; Hood, R. E.

2011-01-01

367

A scheme for computing surface layer turbulent fluxes from mean flow surface observations  

NASA Technical Reports Server (NTRS)

A physical model and computational scheme are developed for generating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at some fixed height in the atmospheric surface layer, where conditions at this reference level are presumed known from observations or the evolving state of a numerical atmospheric circulation model. The method is based on coupling the Monin-Obukov surface layer similarity profiles which include buoyant stability effects on mean velocity, temperature and humidity to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant fluxes at the surface. Additional parameters needed to implement the scheme are the thermal heat capacity of the soil per unit surface area, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity to solar radiation.

Hoffert, M. I.; Storch, J.

1978-01-01

368

Calibration and Validation of Earth-Observing Sensors Using Deployable Surface-Based Sensor Networks  

Microsoft Academic Search

Satellite-based instruments are now routinely used to map the surface of the globe or monitor weather conditions. However, these orbital measurements of ground-based quantities are heavily influenced by external factors, such as air moisture content or surface emissivity. Detailed atmospheric models are created to compensate for these factors, but the satellite system must still be tested over a wide variety

Stephen Williams; Lonnie T. Parker; Ayanna M. Howard

2010-01-01

369

Estimating Long Term Surface Soil Moisture in the GCIP Area From Satellite Microwave Observations  

NASA Technical Reports Server (NTRS)

Soil moisture is an important component of the water and energy balances of the Earth's surface. Furthermore, it has been identified as a parameter of significant potential for improving the accuracy of large-scale land surface-atmosphere interaction models. However, accurate estimates of surface soil moisture are often difficult to make, especially at large spatial scales. Soil moisture is a highly variable land surface parameter, and while point measurements are usually accurate, they are representative only of the immediate site which was sampled. Simple averaging of point values to obtain spatial means often leads to substantial errors. Since remotely sensed observations are already a spatially averaged or areally integrated value, they are ideally suited for measuring land surface parameters, and as such, are a logical input to regional or larger scale land process models. A nine-year database of surface soil moisture is being developed for the Central United States from satellite microwave observations. This region forms much of the GCIP study area, and contains most of the Mississippi, Rio Grande, and Red River drainages. Daytime and nighttime microwave brightness temperatures were observed at a frequency of 6.6 GHz, by the Scanning Multichannel Microwave Radiometer (SMMR), onboard the Nimbus 7 satellite. The life of the SMMR instrument spanned from Nov. 1978 to Aug. 1987. At 6.6 GHz, the instrument provided a spatial resolution of approximately 150 km, and an orbital frequency over any pixel-sized area of about 2 daytime and 2 nighttime passes per week. Ground measurements of surface soil moisture from various locations throughout the study area are used to calibrate the microwave observations. Because ground measurements are usually only single point values, and since the time of satellite coverage does not always coincide with the ground measurements, the soil moisture data were used to calibrate a regional water balance for the top 1, 5, and 10 cm surface layers in order to interpolate daily surface moisture values. Such a climate-based approach is often more appropriate for estimating large-area spatially averaged soil moisture because meteorological data are generally more spatially representative than isolated point measurements of soil moisture. Vegetation radiative transfer characteristics, such as the canopy transmissivity, were estimated from vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and the 37 GHz Microwave Polarization Difference Index (MPDI). Passive microwave remote sensing presents the greatest potential for providing regular spatially representative estimates of surface soil moisture at global scales. Real time estimates should improve weather and climate modelling efforts, while the development of historical data sets will provide necessary information for simulation and validation of long-term climate and global change studies.

Owe, Manfred; deJeu, Vrije; VandeGriend, Adriaan A.

2000-01-01

370

Weathering patterns in high-latitude regolith  

NASA Astrophysics Data System (ADS)

Large areas distributed on the Earth's surface are covered by regolith, an unconsolidated heterogeneous material overlying bedrock. In high-latitude areas, most of the land surface has been reworked and eroded by both glacial and fluvial processes, leaving only remnants of formerly extensive regolith covers. In an effort to further the understanding of weathering patterns and processes in old regolith covers, a comprehensive study of localities spread across Norway was carried out. On the basis of the distribution of minerals and elements within regolith, as well as its internal structure and geomorphologic setting, we ascertained that it was formed in situ and originated in pre-Quaternary times. There are similarities between the study sites with respect to regolith thickness, zonation, and composition. The Chemical Index of Alteration (CIA) and the Weathering Index of Parker (WIP) suggests that the degree of chemical weathering in the regolith is advanced compared to the parental bedrock with a maximum change of over 80%, which indicates a substantial increase in the proportion of secondary versus primary minerals. Mineral analysis identified kaolinite and gibbsite, which are considered indicative of advanced weathering and therefore support this observation. On the basis of statistical relationships between different grain size fractions (<125 ?m), we observed a consistent pattern, which revealed that physical weathering becomes progressively less important in the production of grains smaller than 32 ?m. On the basis of this finding, we infer that chemical weathering progressively dominates the production of fine silt, very fine silt, and clay, whereas physical weathering primarily controls the production of grain size fractions larger than 32 ?m. This particular pattern is suggested to be an intrinsic feature in the formation of weathered high-latitude regolith.

StrøMsøE, JøRund Raukleiv; Paasche, Øyvind

2011-09-01

371

Weathering patterns in high latitude regolith  

NASA Astrophysics Data System (ADS)

Large areas distributed on the Earth's surface are covered by regolith, an unconsolidated heterogeneous material overlying bedrock. In high latitude areas, most of the land surface has been reworked and eroded by both glacial and fluvial processes, leaving only remnants of formerly extensive regolith covers. In an effort to further the understanding of weathering patterns and processes in old regolith covers, a comprehensive study of localities spread across Norway was carried out. Based on the distribution of minerals and elements within regolith, as well as its internal structure and geomorphologic setting, we ascertained that it was formed in situ and originated in pre-Quaternary times. There are similarities between the study sites with respect to regolith thickness, zonation, and composition. The Chemical Index of Alteration (CIA) and the Weathering Index of Parker (WIP) suggests that the degree of chemical weathering in the regolith is advanced compared to the parental bedrock with a maximum change of over 80%, which indicates a substantial increase in the proportion of secondary versus primary minerals. Mineral analysis identified kaolinite and gibbsite, which are considered indicative of advanced weathering and therefore support this observation. On the basis of statistical relationships between different grain size fractions (<125 ?m), we observed a consistent pattern, which revealed that physical weathering becomes progressively less important in the production of grains smaller than 32 ?m. Based on this finding, we infer that chemical weathering progressively dominates the production of fine silt, very fine silt, and clay, whereas physical weathering primarily controls the production of grain size fractions larger than 32 ?m. This particular pattern is suggested to be an intrinsic feature in the formation of weathered high latitude regolith.

Stromsoe, J.; Paasche, O.

2011-12-01

372

Geochemical investigation of weathering processes in a forested headwater catchment: Mass-balance weathering fluxes  

USGS Publications Warehouse

Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basic hydrology. O'Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile. ?? 2008 The Mineralogical Society.

Jones, B. F.; Herman, J. S.

2008-01-01

373

Surface heat budget at the Nordic Seas in Lagrangian observations  

NASA Astrophysics Data System (ADS)

In the Nordic Seas, the warm, inflowing Atlantic Water is cooled until it is dense enough to sink. Thereafter it circulates at depth, eventually feeding the North Atlantic Deep Water. The air-sea interaction which facilitates this cooling is a complex process involving diverse phenomena, from surface heating to turbulent entrainment at the base of the ocean surface mixed layer. In the present study, we use 486 freely-drifting surface buoys to observe temperature changes on water parcels and the response to air-sea heat fluxes. Such Lagrangian observations advantageously 'filter out' horizontal heat fluxes, since the buoys are advected by the flow, allowing one to focus on the vertical exchanges. We examine the temporal evolution of temperature on the drifters and the correlations with surface heat fluxes, obtained from ECMWF ERA-Interim reanalyses. The frequency spectra indicate a clear ?-2 dependence at frequencies higher than roughly 1/40 days-1. The temperature fluctuations on the other hand are correlated with surface fluxes only at the longer time scales. We then show how the Lagrangian temperature can be represented as a stochastic process, with a deterministic portion determined by the low frequency atmospheric forcing and a white noise perturbation. This is in line with previous studies of the ocean surface response to stochastic wind forcing. What distinguishes the present model is the deterministic part, which must account for the gradual cooling of the water parcels.

de La Lama, Marta S.; Isachsen, Pål E.; Koszalka, Inga; Lacasce, Joseph H.

2014-05-01

374

Thermal properties of Pluto's and Charon's surfaces from Spitzer observations  

NASA Astrophysics Data System (ADS)

We report on thermal observations of the Pluto-Charon system acquired by the Spitzer observatory in August-September 2004. The observations, which consist of (i) photometric measurements (8 visits) with the Multiband Imaging Photometer (MIPS) at 24, 70 and 160 ?m and (ii) low-resolution spectra (8 visits) over 20-37 ?m with the Infrared Spectrometer (IRS), clearly exhibit the thermal lightcurve of Pluto/Charon at a variety of wavelengths. They further indicate a steady decrease of the system brightness temperature with increasing wavelength. Observations are analyzed by means of a thermophysical model, including the effects of thermal conduction and surface roughness, and using a multi-terrain description of Pluto and Charon surfaces in accordance with visible imaging and lightcurves, and visible and near-infrared spectroscopy. Three units are considered for Pluto, respectively covered by N 2 ice, CH 4 ice, and a tholin/H 2O mix. Essential model parameters are the thermal inertia of Pluto and Charon surfaces and the spectral and bolometric emissivity of the various units. A new and improved value of Pluto's surface thermal inertia, referring to the CH 4 and tholin/H 2O areas, is determined to be ?Pl = 20-30 J m -2 s -1/2 K -1 (MKS). The high-quality 24-?m lightcurve permits a precise assessment of Charon's thermal emission, indicating a mean surface temperature of 55.4 ± 2.6 K. Although Charon is on average warmer than Pluto, it is also not in instantaneous equilibrium with solar radiation. Charon's surface thermal inertia is in the range ?Ch = 10-150 MKS, though most model solutions point to ?Ch = 10-20 MKS. Pluto and Charon thermal inertias appear much lower than values expected for compact ices, probably resulting from high surface porosity and poor surface consolidation. Comparison between Charon's thermal inertia and even lower values estimated for two other H 2O-covered Kuiper-Belt objects suggests that a vertical gradient of conductivity exists in the upper surface of these bodies. Finally, the observations indicate that the spectral emissivity of methane ice is close to unity at 24 ?m and decreases with increasing wavelength to ˜0.6 at 100 ?m. Future observations of thermal lightcurves over 70-500 ?m by Herschel should be very valuable to further constrain the emissivity behavior of the Pluto terrains.

Lellouch, Emmanuel; Stansberry, John; Emery, Josh; Grundy, Will; Cruikshank, Dale P.

2011-08-01

375

Optical observation of evanescent surface magnons in thin magnetic films  

SciTech Connect

A new type of nonpropagating surface-wave-like magnon has been detected in yttrium iron garnet films (YIG) in a magnetostatic wave (MSW) device structure using Brillouin light scattering. The measurements were carried out on a YIG film stripline device operated at 2--4 GHz. With an applied magnetic field parallel to the stripline, magnon signals were observed at fields above the surface wave band edge. Theory shows that highly localized, evanescent surface modes can exist at such fields, but only when a ground plane is present; the bandwidth in field or frequency is inversely proportional to the separation between the film and the ground plane. The observed evanescent wave band limits are in good agreement with the theoretical values.

Srinivasan, G.; Emtage, P.R.; Booth, J.G.; Patton, C.E.

1988-04-15

376

HST observations of Triton: Evidence of a changing surface.  

NASA Astrophysics Data System (ADS)

Triton is one of the few bodies in the solar system with observed cryo-volcanic activity, in the form of plumes (Soderblom et al. 1990). Prompted by evidence from previous observations at ground and space-based telescopes of possible seasonal surface changes on Triton (Herbert et al. 2004 and Young & Stern 1999), we proposed to confirm and characterize these changes using the HST ACS instrument to image Triton at UV,B,V,I and Methane-band wavelengths over as much of its surface as visible from near Earth. With Triton's angular diameter of nearly 0.13 arcsec in size, ACS's HRC mode afforded an approximately 5X5 pixel image of Triton's surface. With HST's resolution, four regions could be resolved at a time, and particular surface features were restricted to a certain quadrant of Triton's surface. Our request for 6 observing longitudes has allowed us to resolve the longitude of surface features to within 60 degrees. Preliminary analysis indicates a rotation light curve amplitude in excess of that predicted by static models (Hillier et al. 1994 & Hillier 1999). We will attempt to determine the resurfacing rates and set model constraints on activity and surface temperature as well as composition. Such constraints have profound implications for our understanding of Triton's evolution as well as the history of other outer solar system bodies, including outer solar system satellites that may undergo similar geophysical processes or have similar composition. Herbert, B.D., Buratti, B., Schmidt, B., & Bauer, J. 2003, AGU Fall Meeting Abstracts, 443. Hillier, J.K. 1999, Icarus, 139, 202. Hillier, J., Veverka, J., Helfenstein, P., & Lee, P. 1994, Icarus, 109, 296. Soderblom, L.A., Becker, T.L., Kieffer, S.W., Brown, R.H., Hansen, C.J., & Johnson, T.V. 1990, Science, 250, 410. Young, L.A., & Stern, A.S., AJ, 122, 449.

Bauer, J. M.; Buratti, B. J.

2006-05-01

377

Weather and Climate.  

National Technical Information Service (NTIS)

Recommendations for using space observations of weather and climate to aid in solving earth based problems are given. Special attention was given to: (1) extending useful forecasting capability of space systems, (2) reducing social, economic, and human lo...

1975-01-01

378

Predicting Weather  

NSDL National Science Digital Library

By performing the activities presented in this website, fourth grade students can learn about weather instruments and data collection. This website, produced by the Government of Saskatchewan, also explores how the weather can impact local communities. Each activity presented here includes both objectives and assessment techniques for the lesson. Sixteen different activity suggestions provide students and teachers with ample opportunities to explore weather in the classroom.

2008-03-28

379

Weather Experiments  

NSDL National Science Digital Library

Looking for fun ways to learn about weather? Weather Wiz Kids has 39 fun weather related experiments for you to try. These experiments can be done in the classroom with your friends or even at home! Some of the experiments on the site include: tornado in a bottle, make lightning, make it rain, cloud in a bottle, what's in the wind, the Doppler Effect, and baking soda volcano.

2010-01-01

380

Experimental Weathering of Silicates and Carbonates in a SO_2 Atmosphere: Implications for the Martian Surface Mineralogy  

NASA Astrophysics Data System (ADS)

Weathering experiments of carbonates and silicates in a SO_2 atmosphere and water or water plus hydrogen peroxide result in differences in nature and abundance of secondary phases, favoring sulfites in the first case and sulfates in the second.

Chevrier, V. F.; Lozano, C. G.; Altheide, T. S.

2012-03-01

381

Space weather  

NASA Astrophysics Data System (ADS)

Space weather is caused by conditions on the Sun and in the solar wind, the magnetosphere, ionosphere and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can affect human life or health. It affects man-made systems such as satellite electronics, terrestrial power grids and radio communications. This paper provides an overview of how space weather arises in the solar terrestrial system and how physical processes are able to cause space weather effects. We also discuss European perspectives and activities geared towards the possible initiation of a European Space Weather programme.

Glover, Alexi; Daly, Eamonn; Hilgers, Alain; Berghmans, David

2002-05-01

382

Improving Numerical Weather Predictions of Summertime Precipitation Over the Southeastern U.S. Through a High-Resolution Initialization of the Surface State  

NASA Technical Reports Server (NTRS)

It is hypothesized that high-resolution, accurate representations of surface properties such as soil moisture and sea surface temperature are necessary to improve simulations of summertime pulse-type convective precipitation in high resolution models. This paper presents model verification results of a case study period from June-August 2008 over the Southeastern U.S. using the Weather Research and Forecasting numerical weather prediction model. Experimental simulations initialized with high-resolution land surface fields from the NASA Land Information System (LIS) and sea surface temperature (SST) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) are compared to a set of control simulations initialized with interpolated fields from the National Centers for Environmental Prediction 12-km North American Mesoscale model. The LIS land surface and MODIS SSTs provide a more detailed surface initialization at a resolution comparable to the 4-km model grid spacing. Soil moisture from the LIS spin-up run is shown to respond better to the extreme rainfall of Tropical Storm Fay in August 2008 over the Florida peninsula. The LIS has slightly lower errors and higher anomaly correlations in the top soil layer, but exhibits a stronger dry bias in the root zone. The model sensitivity to the alternative surface initial conditions is examined for a sample case, showing that the LIS/MODIS data substantially impact surface and boundary layer properties.

Case, Jonathan L.; Kumar, Sujay V.; Krikishen, Jayanthi; Jedlovec, Gary J.

2011-01-01

383

Observed land surface temperature evolution during dry spells across Europe  

NASA Astrophysics Data System (ADS)

Soil moisture driven land-atmosphere feedbacks are known to influence the evolution of European summer heat waves. Climate models disagree on where and how strongly the land surface energy budget is limited by soil moisture. Observations of evapotranspiration during rain-free periods provide timescales of response at flux sites, but are too few to ascertain a representative regional response. At the large scale, however, remotely sensed land surface temperature (LST) data provide an instantaneous snapshot of the land surface thermal state, which is related closely to the surface energy partition; a freely-evaporating surface has a lower LST than a water-stressed surface. Here 1 km MODIS-Terra LST are used in combination with gridded air temperature to explore how the surface warms during rain-free periods. The analysis is performed using the mid-morning overpass data (10:30 local time), aggregated up to 0.5 degree resolution across Europe. Using gridded precipitation, a set of 94350 dry spell events, lasting 10 days or longer, were identified for the period 2000 to 2012, April through to October each year. Across all dry spells, we build up a composite of LST having accounted for variations in air temperature. This provides a measure of how rapidly the surface warms up relative to the atmosphere, and is related to variability in sensible heat flux. By considering dry spells as short as 10 days a warming signal can be observed which is consistent with an increasing soil moisture constraint on evapotranspiration. To better understand the observed response, dry spell events are stratified by antecedent precipitation, land cover type and geographic regions. Stratifying by antecedent precipitation (used as a proxy for soil moisture) reveals that rates of warming are sensitive to soil moisture levels at the onset of a dry spell. Under dry antecedent conditions, rates of warming over 10 days are weak as the surface is already dry, consistent with little change in the partitioning of surface fluxes. For wetter antecedent conditions, rates of warming are stronger, indicating a change in the surface energy balance in response to a drying surface and a shift toward sensible heat production. Under the wettest antecedent conditions, the dry spell warming rate weakens again consistent with high rates of evapotranspiration being maintained ~5 days into the dry spell. For forests, lower rates of warming are observed than over croplands. Regional variations in the composite LST show different responses in terms of the average rates of warming. This study provides a unique analysis of large-scale observations of LST, from which the surface energy balance response to levels of soil moisture can be identified. Capturing the temporal evolution of LST during rain-free periods provides a new opportunity to evaluate this critical feedback process in climate models.

Folwell, Sonja S.; Harris, Phil P.; Taylor, Christopher M.

2014-05-01

384

Observation of Sea Ice Surface Thermal States Under Cloud Cover  

NASA Technical Reports Server (NTRS)

Clouds interfere with the distribution of short-wave and long-wave radiations over sea ice, and thereby strongly affect the surface energy balance in polar regions. To evaluate the overall effects of clouds on climatic feedback processes in the atmosphere-ice-ocean system, the challenge is to observe sea ice surface thermal states under both clear sky and cloudy conditions. From laboratory experiments, we show that C-band radar (transparent to clouds) backscatter is very sensitive to the surface temperature of first-year sea ice. The effect of sea ice surface temperature on the magnitude of backscatter change depends on the thermal regimes of sea ice thermodyn