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1

Weather radar measurements in data-driven rainfall-runoff models  

Microsoft Academic Search

Meanwhile data-driven models have become established tools in the field of hydrology. Most of these models use rain gauge data as precipitation inputs. Weather radar data are rarely utilized in rainfall-runoff models basically because often these data are not available for disposal. But particularly the gapless spatial coverage of the weather radar is beneficial to detect also small rainfall cells

R. Teschl; W. L. Randeu; F. Teschl

2009-01-01

2

An integrated procedure for rainfall estimation using C-band dual-polarization weather radars  

Microsoft Academic Search

Weather radar polarimetric techniques have been widely studied due to their potential to improve radar rainfall estimation and to infer on the microphysical characteristics of clouds and precipitation. Nowadays, polarimetric techniques are receiving an increasing attention from meteorological services. In fact, programs aiming at upgrading national weather radar networks with polarimetry are ongoing in both in Europe and in USA.

Luca Baldini; Eugenio Gorgucci; Vito Romaniello

2008-01-01

3

A study on weather radar data assimilation for numerical rainfall prediction  

NASA Astrophysics Data System (ADS)

Mesoscale NWP model is gaining more attention in providing high-resolution rainfall forecasts at the catchment scale for real-time flood forecasting. The model accuracy is however negatively affected by the "spin-up" effect and errors in the initial and lateral boundary conditions. Synoptic studies in the meteorological area have shown that the assimilation of operational observations especially the weather radar data can improve the reliability of the rainfall forecasts from the NWP models. This study aims at investigating the potential of radar data assimilation in improving the NWP rainfall forecasts that have direct benefits for hydrological applications. The Weather Research and Forecasting (WRF) model is adopted to generate 10 km rainfall forecasts for a 24 h storm event in the Brue catchment (135.2 km2) located in Southwest England. Radar reflectivity from the lowest scan elevation of a C-band weather radar is assimilated by using the three dimensional variational (3D-Var) data assimilation technique. Considering the unsatisfactory quality of radar data compared to the rain gauges, the radar data is assimilated in both the original form and an improved form based on a real-time correction ratio developed according to the rain gauge observations. Traditional meteorological observations including the surface and upper-air measurements of pressure, temperature, humidity and wind speed are also assimilated as a bench mark to better evaluate and test the potential of radar data assimilation. Four modes of data assimilation are thus carried out on different types or combinations of observations: (1) traditional meteorological data; (2) radar reflectivity; (3) corrected radar reflectivity; (4) a combination of the original reflectivity and meteorological data; and (5) a combination of the corrected reflectivity and meteorological data. The WRF rainfall forecasts before and after different modes of data assimilation is evaluated by examining the rainfall cumulative curves and the rainfall totals which have direct impact on rainfall-runoff transformation in hydrological applications. It is found that by solely assimilating radar data, the improvement of rainfall forecasts are not as obvious as assimilating meteorological data; whereas the positive effect of radar data can be seen when combined with the traditional meteorological data, which leads to the best rainfall forecasts among the five modes. To further improve the effect of radar data assimilation, limitations of the radar correction ratio developed in this study is discussed and suggestions are made on more efficient utilisation of radar data in NWP assimilation.

Liu, J.; Bray, M.; Han, D.

2012-09-01

4

Rainfall rate retrieval in presence of path attenuation using C-band polarimetric weather radars  

NASA Astrophysics Data System (ADS)

Weather radar systems are very suitable tools for the monitoring of extreme rainfall events providing measurements with high spatial and temporal resolution over a wide geographical area. Nevertheless, radar rainfall retrieval at C-band is prone to several error sources, such as rain path attenuation which affects the accuracy of inversion algorithms. In this paper, the so-called rain profiling techniques (namely the surface reference method FV and the polarimetric method ZPHI) are applied to correct rain path attenuation and a new neural network algorithm is proposed to estimate the rain rate from the corrected measurements of reflectivity and differential reflectivity. A stochastic model, based on disdrometer measurements, is used to generate realistic range profiles of raindrop size distribution parameters while a T-matrix solution technique is adopted to compute the corresponding polarimetric variables. A sensitivity analysis is performed in order to evaluate the expected errors of these methods. It has been found that the ZPHI method is more reliable than FV, being less sensitive to calibration errors. Moreover, the proposed neural network algorithm has shown more accurate rain rate estimates than the corresponding parametric algorithm, especially in presence of calibration errors.

Vulpiani, G.; Marzano, F. S.; Chandrasekar, V.; Berne, A.; Uijlenhoet, R.

2006-06-01

5

AN EXPERIMENT OF RAINFALL PREDICTION OVER THE ODRA CATCHMENT BY COMBINING WEATHER RADAR AND A NUMERICAL WEATHER MODEL  

Microsoft Academic Search

As more and more flood forecasting systems utilise quantitative precipitation forecast (QPF) in order to get a longer lead time, particularly for flash flood, attention has fallen upon the quality of QPF in such a model-train context. Weather radar and numerical weather predication (NWP) are two important sources for quantitative precipitation forecast both of which have pros and cons. In

I. D. CLUCKIE; M. A. RICO-RAMIREZ; Y. XUAN; W. SZALINSKA

6

Aviation weather radar  

Microsoft Academic Search

The Federal Aviation Administration has established three ground-based weather radar programs. The terminal Doppler weather radar (TDWR) and weather system processor (WSP) provide wind shear detection capability for air traffic controllers in the terminal area. These systems also reduce weather related delays. The next generation weather radar (NEXRAD) is used by the FAA to improve safety and reduce weather related

D. H. Turnbull

1995-01-01

7

Doppler weather radar  

Microsoft Academic Search

The Doppler weather radar and its signals are examined from elementary considerations to show the origin and development of useful weather echo properties such as signal-to-noise ratio (SNR), range correlation, signal statistics, etc. We present a form of the weather radar equation which explicitly shows the echo power loss due to finite receiver bandwidth and how it is related to

RICHARD J. DOVIAK; DUSAN S. ZRNIC; DALE S. SIRMANS

1979-01-01

8

Forecasting weather radar propagation conditions  

NASA Astrophysics Data System (ADS)

The increasing use of weather radar quantitative precipitation estimates, particularly in automatic applications such as operational hydrometeorological modelling or assimilation in numerical weather prediction (NWP) models, has promoted the development of quality control procedures on radar data. Anomalous propagation (AP) of the radar beam due to deviation from the standard refractivity vertical profile, is one of the factors that may affect seriously the quality of radar observations because of the increase in quantity and intensity of non-precipitating clutter echoes and consequent contamination of the estimated rainfall field. Another undesired effect of AP is the change in the expected radar echo height, which may be relevant when correcting for beam blockage in radar rainfall estimation in complex terrain. The aim of this paper is to study the use of NWP mesoscale forecasts to predict and monitor AP events. A nested 15-km grid resolution version of the MASS model has been used to retrieve refractivity profiles in the coastal area of Barcelona, near a weather radar and a radiosonde station. Using the refractivity profiles two different magnitudes were computed: the vertical refractivity profile of the lowest 1000 m layer and a ducting index which describes the existence and intensity of the most super-refractive layer contained in the lowest 3-km layer. A comparison between model forecasts and radiosonde diagnostics during a six-month period showed that the model tended to underestimate the degree of super-refraction, with a bias of 4 km-1 and RMSE of 11 km-1 in the 1-km vertical refractivity gradient. Further analysis of the data showed that a combination of previous observations and forecasts allowed to produce modified forecasts improving the original direct model output, decreasing substantially the bias, reducing the RMSE by 20% and improving the skill by 40%, beating also radiosonde observations persistence.

Bech, J.; Codina, B.; Lorente, J.

2007-06-01

9

Analysis of weather radar and rain gauges for flood forecasting  

Microsoft Academic Search

Real time rainfall for flood forecasting is predominately measured by rain gauges and weather radars. Analysis of rainfall data measured simultaneously by a dense rain gauge network and weather radar over the Brue catchment, during a period of six years, was undertaken using Principal Component Analysis and Cluster Analysis. Wind, temperature, relative humidity for the major storms events over the

M. T. J. Bray; D. Han; I. Cluckie; M. Rico-Ramirez

10

Terminal Doppler weather radar  

Microsoft Academic Search

The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver\\/exciter, the digital signal processor, and the radar product generator\\/remote monitoring subsystem. Attention is also given to the processes of the

M. Michelson; W. W. Shrader; J. G. Wieler

1990-01-01

11

Probabilistic forecasts based on radar rainfall uncertainty  

NASA Astrophysics Data System (ADS)

The potential advantages resulting from integrating weather radar rainfall estimates in hydro-meteorological forecasting systems is limited by the inherent uncertainty affecting radar rainfall measurements, which is due to various sources of error [1-3]. The improvement of quality control and correction techniques is recognized to play a role for the future improvement of radar-based flow predictions. However, the knowledge of the uncertainty affecting radar rainfall data can also be effectively used to build a hydro-meteorological forecasting system in a probabilistic framework. This work discusses the results of the implementation of a novel probabilistic forecasting system developed to improve ensemble predictions over a small urban area located in the North of England. An ensemble of radar rainfall fields can be determined as the sum of a deterministic component and a perturbation field, the latter being informed by the knowledge of the spatial-temporal characteristics of the radar error assessed with reference to rain-gauges measurements. This approach is similar to the REAL system [4] developed for use in the Southern-Alps. The radar uncertainty estimate can then be propagated with a nowcasting model, used to extrapolate an ensemble of radar rainfall forecasts, which can ultimately drive hydrological ensemble predictions. A radar ensemble generator has been calibrated using radar rainfall data made available from the UK Met Office after applying post-processing and corrections algorithms [5-6]. One hour rainfall accumulations from 235 rain gauges recorded for the year 2007 have provided the reference to determine the radar error. Statistics describing the spatial characteristics of the error (i.e. mean and covariance) have been computed off-line at gauges location, along with the parameters describing the error temporal correlation. A system has then been set up to impose the space-time error properties to stochastic perturbations, generated in real-time at gauges location, and then interpolated back onto the radar domain, in order to obtain probabilistic radar rainfall fields in real time. The deterministic nowcasting model integrated in the STEPS system [7-8] has been used for the purpose of propagating the uncertainty and assessing the benefit of implementing the radar ensemble generator for probabilistic rainfall forecasts and ultimately sewer flow predictions. For this purpose, events representative of different types of precipitation (i.e. stratiform/convective) and significant at the urban catchment scale (i.e. in terms of sewer overflow within the urban drainage system) have been selected. As high spatial/temporal resolution is required to the forecasts for their use in urban areas [9-11], the probabilistic nowcasts have been set up to be produced at 1 km resolution and 5 min intervals. The forecasting chain is completed by a hydrodynamic model of the urban drainage network. The aim of this work is to discuss the implementation of this probabilistic system, which takes into account the radar error to characterize the forecast uncertainty, with consequent potential benefits in the management of urban systems. It will also allow a comparison with previous findings related to the analysis of different approaches to uncertainty estimation and quantification in terms of rainfall [12] and flows at the urban scale [13]. Acknowledgements The authors would like to acknowledge the BADC, the UK Met Office and Dr. Alan Seed from the Australian Bureau of Meteorology for providing the radar data and the nowcasting model. The authors acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) via grant EP/I012222/1.

Liguori, S.; Rico-Ramirez, M. A.

2012-04-01

12

Real-time radar rainfall estimation  

NASA Astrophysics Data System (ADS)

This research reports on several aspects of real-time monitoring of the spatial and temporal distribution of rainfall from ground-based weather radar. Optimization of the performance of the National Weather Service's Precipitation Processing Subsystem (PPS) is the first objective. This is achieved by developing a calibration procedure which simultaneously estimates the optimal parameter values by providing a global assessment of the system's performance. Evaluation of the system is based on a data set consisting of two months of radar reflectivity measurements, and hourly raingage rainfall accumulations, from the Melbourne, Florida WSR-88D site. Radar-raingage root mean square (RMS) difference reduction up to 20% with respect to the default system parameter values is demonstrated. Investigation of statistical procedures for real-time adjustment of the mean-field systematic radar rainfall error is the second objective. For this purpose, a data- based Monte Carlo simulation experiment is performed. The study uses an extensive data set of hourly radar rainfall products and raingage accumulations from the Tulsa, Oklahoma WSR-88D site. This intercomparison study concluded to a bias procedure which overall appeared to perform better than the other. The main results from this research are: (1) statistical methods with optimal error model parameters perform significantly better than using only bias observations, and (2) bias adjustment is mostly effective in cold season precipitation measurements. Final objective of this research is development of a new real-time radar rainfall estimation algorithm. The new processing steps introduced in this algorithm are beam- height effect correction, vertical integration, rain classification, and continuous range effect correction. Additionally, the algorithm applies advection correction at the gridded rainfall rates to minimize the temporal sampling effect, and its calibration is cast in a recursive formulation with parameters adjusted in real- time. A new statistical method has been developed for quantification of radar rainfall products uncertainty. Evaluation of the system and the uncertainty quantification method is based on the data set from Melbourne, Florida WSR-88D site. Radar-raingage RMS difference reduction up to 50% with respect to the default PPS is demonstrated for the proposed algorithm.

Anagnostou, Emmanouil Nikolaos

1997-08-01

13

Terminal Doppler weather radar  

NASA Astrophysics Data System (ADS)

The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver/exciter, the digital signal processor, and the radar product generator/remote monitoring subsystem. Attention is also given to the processes of the base data formation, point target removal, signal-to-noise thresholding, and velocity de-aliasing and to the TDWR algorithms and displays. A schematic diagram of the TDWR system is presented.

Michelson, M.; Shrader, W. W.; Wieler, J. G.

1990-02-01

14

STEPS TOWARD IMPROVED RADAR ESTIMATES OF CONVECTIVE RAINFALL USING SPATIAL AVERAGES OBTAINED FROM RAIN GAUGE CLUSTERS  

Microsoft Academic Search

For the purpose of validating rainfall estimates from the Tropical Rainfall Measurement Mission's (TRMM) spaceborne precipitation radar, and from the National Weather Service's WSR-88D radar covering east central Florida, correlation with ground based rain gauge data is needed. However, a problem regularly encountered when correlating radar rainfall estimates with gauge measurements is the difference in measurement geometry. A gauge measures

T. Kasparis; L. Jones; P. Glitto; D. Sharp; F. Merceret; G. McFarquhar; B. Fisher

1998-01-01

15

Weather Radar Estimations Feeding an Artificial Neural Network Model  

Microsoft Academic Search

The application of ANNs (Artifi cial Neural Networks) has been studied by many researchers in modelling rainfall runoff processes. However, the work so far has been focused on the ra- infall data from traditional raingauges. Weather radar is a modern technology which could provide high resolution rainfall in time and space. In this study, a comparison in rainfall runoff modelling

Gustavo Cerda Villafaña; Sergio Ledesma; Dawei Han

2008-01-01

16

INTEGRATED CONTROL OF COMBINED SEWER REGULATORS USING WEATHER RADAR  

EPA Science Inventory

Integrated operation was simulated of ten dynamic combined sewer regulators on a Montreal interceptor. Detailed review of digital recording weather radar capabilities indicated that it is potentially the best rainfall estimation means for accomplishing the runoff prediction that ...

17

Improvement of X-band radar rainfall estimates using a microwave link  

NASA Astrophysics Data System (ADS)

In recent years the significance of highly resolved rainfall information in space and time for hydrological applications increased steadily. Weather radar systems provide this information but the derivation of quantitatively reliable radar rainfall estimates is still known to be problematic. The attenuation of the radar signal by rainfall has been identified as crucial and especially X-band radars are affected by this phenomenon. The current methods of correcting for attenuation face many problems, mainly because the actual amount of attenuation is unknown. In this paper attenuation and rainfall information derived from a microwave link are used as a reference to correct an X-band radar for rainfall. A microwave link receiver is co-located with an X-band weather radar in Essen, Germany. Therefore, the microwave link provides path integrated attenuation and rainfall information parallel to a radar beam over a distance of 30 km. The correction of radar rainfall is done in two steps: first, the radar data are corrected for attenuation and in a second step the microwave link derived rainfall is used together with information obtained from distrometer data to calculate the rainfall from the corrected radar reflectivities. A network of twelve rain gauges located in the vicinity of the link path provide a measure of the ‘ground truth’ rainfall. It is shown that the microwave link gives valuable information to improve the radar rainfall estimates of the X-band radar.

Krämer, S.; Verworn, H.-R.; Redder, A.

2005-09-01

18

Runoff Analysis Considering Orographical Features Using Dual Polarization Radar Rainfall  

NASA Astrophysics Data System (ADS)

Recently, the necessity for rainfall estimation and forecasting using the radar is being highlighted, due to the frequent occurrence of torrential rainfall resulting from abnormal changes of weather. Radar rainfall data represents temporal and spatial distributions properly and replace the existing rain gauge networks. It is also frequently applied in many hydrologic field researches. However, the radar rainfall data has an accuracy limitation since it estimates rainfall, by monitoring clouds and precipitation particles formed around the surface of the earth(1.5-3km above the surface) or the atmosphere. In a condition like Korea where nearly 70% of the land is covered by mountainous areas, there are lots of restrictions to use rainfall radar, because of the occurrence of beam blocking areas by topography. This study is aiming at analyzing runoff and examining the applicability of (R(Z), R(ZDR) and R(KDP)) provided by the Han River Flood Control Office(HRFCO) based on the basin elevation of Nakdong river watershed. For this purpose, the amount of radar rainfall of each rainfall event was estimated according to three sub-basins of Nakdong river watershed with the average basin elevation above 400m which are Namgang dam, Andong dam and Hapcheon dam and also another three sub-basins with the average basin elevation below 150m which are Waegwan, Changryeong and Goryeong. After runoff analysis using a distribution model, Vflo model, the results were reviewed and compared with the observed runoff. This study estimated the rainfall by using the radar-rainfall transform formulas, (R(Z), R(Z,ZDR) and R(Z,ZDR,KDP) for four stormwater events and compared the results with the point rainfall of the rain gauge. As the result, it was overestimated or underestimated, depending on rainfall events. Also, calculation indicates that the values from R(Z,ZDR) and R(Z,ZDR,KDP) relatively showed the most similar results. Moreover the runoff analysis using the estimated radar rainfall is performed. Then hydrologic component of the runoff hydrographs, peak flows and total runoffs from the estimated rainfall and the observed rainfall are compared. The results show that hydrologic components have high fluctuations depending on storm rainfall event. Thus, it is necessary to choose appropriate radar rainfall data derived from the above radar rainfall transform formulas to analyze the runoff of radar rainfall. The simulated hydrograph by radar in the three basins of agricultural areas is more similar to the observed hydrograph than the other three basins of mountainous areas. Especially the peak flow and shape of hydrograph of the agricultural areas is much closer to the observed ones than that of mountainous areas. This result comes from the difference of radar rainfall depending on the basin elevation. Therefore we need the examination of radar rainfall transform formulas following rainfall event and runoff analysis based on basin elevation for the improvement of radar rainfall application. Acknowledgment This study was financially supported by the Construction Technology Innovation Program(08-Tech-Inovation-F01) through the Research Center of Flood Defence Technology for Next Generation in Korea Institute of Construction & Transportation Technology Evaluation and Planning(KICTEP) of Ministry of Land, Transport and Maritime Affairs(MLTM)

Noh, Hui-seong; Shin, Hyun-seok; Kang, Na-rae; Lee, Choong-Ke; Kim, Hung-soo

2013-04-01

19

Evaluation of Radar Rainfall Estimation in Widespread Early Spring Rainfall Events  

NASA Astrophysics Data System (ADS)

Significant discrepancies can exist between actual and estimated rainfall with the interaction of biases and random error being documented in a number of studies. Numerous reports have demonstrated strong scale dependence in the uncertainties or errors in radar rainfall estimation strategies. This study addresses issues of scale, radar-range and uncertainty of weather radar rainfall measurements under early spring conditions. Rainfall measurement analysis is focused on XPOL (mobile X-band dual polarization weather radar) retrievals from late March through early May 2002 in Northeastern Connecticut, US. The applicable XPOL dataset has been refined through attenuation correction, considerations of contamination and vertical profiles adjustment and noise to twelve rainfall events at a base resolution of 300-meter grids every five minutes. XPOL measurements are validated with sixteen raingauges dispersed in the representative 424 km2 Mansfield Watershed at a maximum range of 23 km. The comparison dataset is taken from the NEXRAD stage-III bias adjusted hourly rainfall rates. This specific data is drawn from the most proximal National Weather Service radars in Upton, NY and Boston, MA each over 100 km away, demonstrating gridded rainfall on a 4-kilometer scale. Several statistical evaluations are employed to study the scale effects and cross-platform radar differences. XPOL radar observations are aggregated to coarser spatial grids; in successive aggregations we test the relative error of selected points against raingauge validation. Spatial XPOL data can be matched directly to NEXRAD stage III data thereby giving an indication of the internal variance of NEXRAD pixels. The assimilated internal variability of NEXRAD rain retrievals may offer insight into the bias and uncertainty of the system and information on the radar-gauge comparison uncertainty.

Knox, R. G.; Anagnostou, E. N.

2004-05-01

20

Efficient Ways to Learn Weather Radar Polarimetry  

ERIC Educational Resources Information Center

The U.S. weather radar network is currently being upgraded with dual-polarization capability. Weather radar polarimetry is an interdisciplinary area of engineering and meteorology. This paper presents efficient ways to learn weather radar polarimetry through several basic and practical topics. These topics include: 1) hydrometeor scattering model…

Cao, Qing; Yeary, M. B.; Zhang, Guifu

2012-01-01

21

Investigating rainfall estimation from radar measurements using neural networks  

NASA Astrophysics Data System (ADS)

Rainfall observed on the ground is dependent on the four dimensional structure of precipitation aloft. Scanning radars can observe the four dimensional structure of precipitation. Neural network is a nonparametric method to represent the nonlinear relationship between radar measurements and rainfall rate. The relationship is derived directly from a dataset consisting of radar measurements and rain gauge measurements. The performance of neural network based rainfall estimation is subject to many factors, such as the representativeness and sufficiency of the training dataset, the generalization capability of the network to new data, seasonal changes, and regional changes. Improving the performance of the neural network for real time applications is of great interest. The goal of this paper is to investigate the performance of rainfall estimation based on Radial Basis Function (RBF) neural networks using radar reflectivity as input and rain gauge as the target. Data from Melbourne, Florida NEXRAD (Next Generation Weather Radar) ground radar (KMLB) over different years along with rain gauge measurements are used to conduct various investigations related to this problem. A direct gauge comparison study is done to demonstrate the improvement brought in by the neural networks and to show the feasibility of this system. The principal components analysis (PCA) technique is also used to reduce the dimensionality of the training dataset. Reducing the dimensionality of the input training data will reduce the training time as well as reduce the network complexity which will also avoid over fitting.

Alqudah, A.; Chandrasekar, V.; Le, M.

2013-03-01

22

Data selection to assess bias in rainfall radar estimates: An entropy-based method  

NASA Astrophysics Data System (ADS)

Miscalibration of radar determines a systematic error (i.e., bias) that is observed in radar estimates of rainfall. Although a rain gauge can provide a pointwise rainfall measurement, weather radar can cover an extended area. To compare the two measurements, it is necessary to individuate the weather radar measurements at the same location as the rain gauge. Bias is measured as the ratio between cumulative rain gauge measurements and the corresponding radar estimates. The rainfall is usually cumulated, taking into account all rainfall events registered in the target area. The contribution of this work is the determination of the optimal number of rainfall events that are necessary to calibrate rainfall radar. The proposed methodology is based on the entropy concept. In particular, the optimal number of events must fulfil two conditions, namely, maximisation of information content and minimisation of redundant information. To verify the methodology, the bias values are estimated with 1) a reduced number of events and 2) all available data. The proposed approach is tested on the Polar 55C weather radar located in the borough area of Rome (IT). The radar is calibrated against rainfall measurements of a couple of rain gauges placed in the Roman city centre. Analysing the information content of all data, it is found that it is possible to reduce the number of rainfall events without losing information in evaluating the bias.

Spina, S.; Sebastianelli, S.; Ridolfi, E.; Russo, F.; Baldini, L.; Alfonso, L.

2013-10-01

23

Australian Weather Watch Radar Home Page  

NSDL National Science Digital Library

The Commonwealth Bureau of Meteorology's Weather Watch Radar website provides up-to-date radar images of the locations of rain in Australia in relation to local features such as coast lines. The newly developed Loops provide four consecutive radar images so that users can view how the weather has been changing in the last forty to fifty minutes. The website provides radar images of past cyclone events as well as updates on severe weather throughout Australia. Those interested in radar systems can discover how the weather radars work and how to interpret the maps. [RME

24

SUB-PIXEL RAINFALL VARIABILITY AND THE IMPLICATIONS FOR UNCERTAINTIES IN RADAR RAINFALL ESTIMATES  

EPA Science Inventory

Radar estimates of rainfall are subject to significant measurement uncertainty. Typically, uncertainties are measured by the discrepancies between real rainfall estimates based on radar reflectivity and point rainfall records of rain gauges. This study investigates how the disc...

25

SUB-PIXEL RAINFALL VARIABILITY AND THE IMPLICATIONS FOR UNCERTAINTIES IN RADAR RAINFALL ESTIMATES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Radar estimates of rainfall are subject to significant measurement uncertainty. Typically, uncertainties are measured by the discrepancies between area rainfall estimates based on radar reflectivity and point rainfall records of rain gauges. This study investigates how the discrepancies can potent...

26

Analyses of the warm season rainfall climatology of the northeastern US using regional climate model simulations and radar rainfall fields  

NASA Astrophysics Data System (ADS)

We examine the warm season (April-September) rainfall climatology of the northeastern US through analyses of high-resolution radar rainfall fields from the Hydro-NEXRAD system and regional climate model simulations using the weather research and forecasting (WRF) model. Analyses center on the 5-year period from 2003 to 2007 and the study area includes the New York-New Jersey metropolitan region covered by radar rainfall fields from the Fort Dix, NJ WSR-88D. The objective of this study is to develop and test tools for examining rainfall climatology, with a special focus on heavy rainfall. An additional emphasis is on rainfall climatology in regions of complex terrain, like the northeastern US, which is characterized by land-water boundaries, large heterogeneity in land use and cover, and mountainous terrain in the western portion of the region. We develop a 5-year record of warm season radar rainfall fields for the study region using the Hydro-NEXRAD system. We perform regional downscaling simulations for the 5-year study period using the WRF model. Radar rainfall fields are used to characterize the interannual, seasonal and diurnal variation of rainfall over the study region and to examine spatial heterogeneity of rainfall. Regional climate model simulations are characterized by a wet bias in the rainfall fields, with the largest bias in the high-elevation regions of the model domain. We show that model simulations capture broad features of the interannual, seasonal, and diurnal variation of rainfall. Model simulations do not capture spatial gradients in radar rainfall fields around the New York metropolitan region and land-water boundaries to the east. The model climatology of convective available potential energy (CAPE) is used to interpret the regional distribution of warm season rainfall and the seasonal and diurnal variability of rainfall. We use hydrologic and meteorological observations from July 2007 to examine the interactions of land surface processes and rainfall from a regional perspective.

Yeung, June K.; Smith, James A.; Villarini, Gabriele; Ntelekos, Alexandros A.; Baeck, Mary Lynn; Krajewski, Witold F.

2011-02-01

27

Next Generation Weather Radar (NEXRAD)/Air Route Surveillance Radar (ARSR) Operational Comparison.  

National Technical Information Service (NTIS)

The National Weather Service (NWS), Federal Aviation Administration (FAA), and Department of Defense are in the process of fielding the Next Generation Weather Radars (NEXRAD). These doppler weather radars, also known as Weather Surveillance Radar (WSR)88...

B. Dunbar J. Mittelman

1993-01-01

28

Next Generation Weather Radar (NEXRAD)/Air Route Surveillance Radar (ARSR) Operational Comparison.  

National Technical Information Service (NTIS)

The National Weather Service (NWS), Federal Aviation Administration (FAA), and Department of Defense are in the process of fielding the Next Generation Weather Radars (NEXRAD). These doppler weather radars, also known as Weather Surveillance Radar (WSR)-8...

B. Dunbar J. Mittelman

1993-01-01

29

14 CFR 135.175 - Airborne weather radar equipment requirements.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Airborne weather radar equipment requirements. 135...and Equipment § 135.175 Airborne weather radar equipment requirements. ...passenger-carrying operations unless approved airborne weather radar equipment is installed in the...

2013-01-01

30

14 CFR 121.357 - Airborne weather radar equipment requirements.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Airborne weather radar equipment requirements. 121...Requirements § 121.357 Airborne weather radar equipment requirements. ...December 31, 1964, unless approved airborne weather radar equipment has been installed...

2013-01-01

31

14 CFR 125.223 - Airborne weather radar equipment requirements.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Airborne weather radar equipment requirements. 125...Requirements § 125.223 Airborne weather radar equipment requirements. (a...passenger-carrying operations unless approved airborne weather radar equipment is installed in the...

2013-01-01

32

Using probabilistic radar rainfall nowcasts and NWP forecasts for flow prediction in urban catchments  

Microsoft Academic Search

The use of Quantitative Precipitation Forecasts (QPFs) to model run-off and flow processes in urban areas is a challenging problem, as rainfall data with high spatial and temporal resolutions are required. Many attempts have been made to use weather radar to produce rainfall forecasts with lead times of a few hours ahead.The UK Met Office in collaboration with the Australian

S. Liguori; M. A. Rico-Ramirez; A. N. A. Schellart; A. J. Saul

33

Weather radar technology and future developments  

Microsoft Academic Search

Radar Hydrology is slowly coming of age and the future develop - ment of quantitative weather radar will be heavily influence d by the Hydro- logical community. There is controversy as to whether or not dual-pola rization radar technology is going to improve the estimation o f precipitation. This paper discusses some of the advantages and disadvantages of the present

IAN DAVID CLUCKIE; MIGUEL ANGEL RICO-RAMIREZ

34

Terminal Doppler weather radar clutter control  

Microsoft Academic Search

A number of unique approaches to clutter rejection which have been validated with the terminal Doppler weather radar (TDWR) testbed radar are described. Key aspects of the detection problem are emphasized from the viewpoint of a radar engineer (as opposed to the meteorological and pattern recognition features of the problem). Attention is focused on mainlobe clutter suppression since it is

James E. Evans; William H. Drury; Daniel P. Hynek; T. Sen Lee

1990-01-01

35

Classification of Ground Clutter and Anomalous Propagation Using Dual-Polarization Weather Radar  

Microsoft Academic Search

This paper presents the results of a study designed to classify weather radar clutter echoes obtained from ground-based dual-polarization weather radar systems. The clutter signals are due to ground clutter, sea clutter, and anomalous propagation echoes, which represent sources of error in quantitative radar rainfall estimation. Fuzzy and Bayes classifiers are evaluated as an alternative approach to traditional polarimetric-based methods.

Miguel Angel Rico-Ramirez; Ian David Cluckie

2008-01-01

36

Representing rainfall uncertainties using radar ensembles: generation of radar based rainfall ensembles for QPE and QPF  

NASA Astrophysics Data System (ADS)

In the last years, new comprehension of the physics underlying the radar measurements as well as new technological advancements have allowed radar community to propose better algorithms and methodologies and significant advancements have been achieved in improving Quantitative Precipitation Estimates (QPE) and Quantitative Precipitation forecasting (QPF) by radar. Thus the study of the 2D uncertainties field associated to these estimates has become an important subject, specially to enhance the use of radar QPE and QPF in hydrological studies, as well as in providing a reference for satellite precipitations measurements. In this context the use of radar-based rainfall ensembles (i.e. equiprobable rainfall field scenarios generated to be compatible with the observations/forecasts and with the inferred structure of the uncertainties) has been seen as an extremely interesting tool to represent their associated uncertainties. The generation of such radar ensembles requires first the full characterization of the 3D field of associated uncertainties (2D spatial plus temporal), since rainfall estimates show an error structure highly correlated in space and time. A full methodology to deal with this kind of radar-based rainfall ensembles is presented. Given a rainfall event, the 2D uncertainty fields associated to the radar estimates are defined for every time step using a benchmark, or reference field, based on the best available estimate of the rainfall field. This benchmark is built using an advanced non parametric interpolation of a dense raingauge network able to use the spatial structure provided by the radar observations, and is confined to the region in which this combination could be taken as a reference measurement (Velasco-Forero et al. 2008, doi:10.1016/j.advwatres.2008.10.004). Then the spatial and temporal structures of these uncertainty fields are characterized and a methodology to generate consistent multiple realisations of them is used to generate the radar-based rainfall ensembles scenarios. This methodology, based on the improvement of the "String of Beads" model (Pegram and Clothier, 2001, doi:10.1016/S0022-1694(00)00373-5), is designed to preserve their main characteristics, such as anisotropy and the temporal variations of their spatial correlation. The discussion of the results on a illustrative case study and their potential interest in hydrological applications will be also discussed .

Sempere-Torres, D.; Llort, X.; Roca, J.; Pegram, G.

2009-04-01

37

Terminal Doppler weather radar clutter control  

NASA Astrophysics Data System (ADS)

A number of unique approaches to clutter rejection which have been validated with the terminal Doppler weather radar (TDWR) testbed radar are described. Key aspects of the detection problem are emphasized from the viewpoint of a radar engineer (as opposed to the meteorological and pattern recognition features of the problem). Attention is focused on mainlobe clutter suppression since it is a principal cause of inadequate detection performance. To provide a framework for the TDWR system discussions, the salient features of the low-altitude wind shear detection environment and the pattern recognition algorithms are first described. Some of the system features which arise from ground clutter suppression considerations are then discussed. Clutter due to out-of-trip weather returns is also an important factor in TDWR system engineering due to the tradeoff between unambiguous velocity and range (coupled with the (range)-2 power law for weather echoes). Some of the radar engineering areas which warrant additional investigation are discussed.

Evans, James E.; Drury, William H.; Hynek, Daniel P.; Lee, T. Sen; Stevens, B. H., Jr.

38

Nowcasting for a high-resolution weather radar network  

NASA Astrophysics Data System (ADS)

Short-term prediction (nowcasting) of high-impact weather events can lead to significant improvement in warnings and advisories and is of great practical importance. Nowcasting using weather radar reflectivity data has been shown to be particularly useful. The Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network provides high-resolution reflectivity data amenable to producing valuable nowcasts. The high-resolution nature of CASA data requires the use of an efficient nowcasting approach, which necessitated the development of the Dynamic Adaptive Radar Tracking of Storms (DARTS) and sinc kernel-based advection nowcasting methodology. This methodology was implemented operationally in the CASA Distributed Collaborative Adaptive Sensing (DCAS) system in a robust and efficient manner necessitated by the high-resolution nature of CASA data and distributed nature of the environment in which the nowcasting system operates. Nowcasts up to 10 min to support emergency manager decision-making and 1--5 min to steer the CASA radar nodes to better observe the advecting storm patterns for forecasters and researchers are currently provided by this system. Results of nowcasting performance during the 2009 CASA IP experiment are presented. Additionally, currently state-of-the-art scale-based filtering methods were adapted and evaluated for use in the CASA DCAS to provide a scale-based analysis of nowcasting. DARTS was also incorporated in the Weather Support to Deicing Decision Making system to provide more accurate and efficient snow water equivalent nowcasts for aircraft deicing decision support relative to the radar-based nowcasting method currently used in the operational system. Results of an evaluation using data collected from 2007--2008 by the Weather Service Radar-1988 Doppler (WSR-88D) located near Denver, Colorado, and the National Center for Atmospheric Research Marshall Test Site near Boulder, Colorado, are presented. DARTS was also used to study the short-term predictability of precipitation patterns depicted by high-resolution reflectivity data observed at microalpha (0.2--2 km) to mesobeta (20--200 km) scales by the CASA radar network. Additionally, DARTS was used to investigate the performance of nowcasting rainfall fields derived from specific differential phase estimates, which have been shown to provide more accurate and robust rainfall estimates compared to those made from radar reflectivity data.

Ruzanski, Evan

39

Bias adjustment and comparison of radar rainfall estimates with rain gauge measurements  

NASA Astrophysics Data System (ADS)

Heavy rainfall events have produced significant damages and casualties in different regions of Romania in the last decades. Some of the areas most at risk of flooding are those within river catchments. Atmospheric precipitation shows a large variation both in space and time, while numerous applications, such as flood forecast, require robust information, capable to describe accurately the precipitation conditions over an area. Quantitative precipitation estimates (QPE) based on weather radar observations are used increasingly more for water management, for monitoring of severe weather events, and in numerical weather prediction models. Combining the rainfall amount measured by ground sensors with radar estimates one can expect more reliable precipitation information. This study aims to compare the radar rainfall estimations with the rain gauge measurements, in order to improve the quantitative precipitation estimation over a given region. Data used to calculate the radar rainfall accumulations is the base reflectivity. The differences between radar-derived and gauge-measured precipitation amounts are evaluated. Spatial distinctions and areas with good radar accuracy for QPE have been emphasized during the investigations. Bias adjustment of short-term radar-based precipitation accumulations is done over a river basin, which serves as test area, in Eastern Romania. In addition, a long-term verification of the bias-adjusted composites over a seven year period using rain gauge data is presented. The adjustment method cannot correct for a range-dependent bias and therefore it is recommended to also use other methods in this regard (e.g., vertical profile of reflectivity adjustment). The output validation aimed to predict the rain gauge amounts using the radar information and the resulted adjustment parameters. The validation demonstrates that the radar data are reliable within approximately 150 km radius, and the comparison with rain gauge measurements can foster consistently the QPE accuracy.

Burcea, Sorin; Carbunaru, Daniel

2013-04-01

40

Radar rainfall estimation from vertical reflectivity profile using neural network  

Microsoft Academic Search

An adaptive radial basis function (RBF) neural network to estimate the ground rainfall from a vertical profile of reflectivity factor (Z) is presented in this paper. This RBF network was applied to two months of WSR-88D radar data to estimate rainfall. Results show that the adaptive RBF developed here can estimate rainfall fairly well. Results were also compared with the

Gang Xu; V. Chandrasekar

2001-01-01

41

Imperfect scaling in distributions of radar-derived rainfall fields  

NASA Astrophysics Data System (ADS)

Fine scale rainfall observations for modeling exercises are often not available, but rather coarser data derived from a variety of sources are used. Effectively using these data sources in models often requires the probability distribution of the data at the applicable scale. Although numerous models for scaling distributions exist, these are often based on theoretical developments, rather than on data. In this study, we develop a model based on the ?-stable distribution of rainfall fields, and tested on 5 min radar data from a Belgian weather radar. We use these data to estimate functions that describe parameters of the distribution over various scales. Moreover, we study how the mean of the distribution and the intermittency change with scale, and validate and design functions to describe the shape parameter of the distribution. This information was combined into an effective model of the distribution. Finally, the model was fitted to data from numerous storms, and the resulting parameters were compared to investigate the change in scaling behavior through time.

van den Berg, M. J.; Delobbe, L.; Verhoest, N. E. C.

2013-09-01

42

Developments in radar and remote-sensing methods for measuring and forecasting rainfall.  

PubMed

Over the last 25 years or so, weather-radar networks have become an integral part of operational meteorological observing systems. While measurements of rainfall made using radar systems have been used qualitatively by weather forecasters, and by some operational hydrologists, acceptance has been limited as a consequence of uncertainties in the quality of the data. Nevertheless, new algorithms for improving the accuracy of radar measurements of rainfall have been developed, including the potential to calibrate radars using the measurements of attenuation on microwave telecommunications links. Likewise, ways of assimilating these data into both meteorological and hydrological models are being developed. In this paper we review the current accuracy of radar estimates of rainfall, pointing out those approaches to the improvement of accuracy which are likely to be most successful operationally. Comment is made on the usefulness of satellite data for estimating rainfall in a flood-forecasting context. Finally, problems in coping with the error characteristics of all these data using both simple schemes and more complex four-dimensional variational analysis are being addressed, and are discussed briefly in this paper. PMID:12804253

Collier, C G

2002-07-15

43

Rainfall Measurements During Hurricane Agnes by Three Overlapping Radars  

Microsoft Academic Search

As part of the International Field Year for the Great Lakes, rainfall measurements were made for hurricane Agnes over the Lake Ontario watershed by two C-band radars and one S-band radar. Two dense networks of raingages were located in radar overlap areas. One of the networks contained a raindrop disdrometer for measuring the number and size of drops.Comparison between radar

James W. Wilson; David M. Pollock

1974-01-01

44

wradlib - An Open Source Library for Weather Radar Data Processing  

NASA Astrophysics Data System (ADS)

Weather radar data is potentially useful in meteorology, hydrology, disaster prevention and mitigation. Its ability to provide information on precipitation with high spatial and temporal resolution over large areas makes it an invaluable tool for short term weather forecasting or flash flood forecasting. The indirect method of measuring the precipitation field, however, leads to a significant number of data artifacts, which usually must be removed or dealt with before the data can be used with acceptable quality. Data processing requires e.g. the transformation of measurements from polar to cartesian coordinates and from reflectivity to rainfall intensity, the composition of data from several radar sites in a common grid, clutter identification and removal, attenuation and VPR corrections, gauge adjustment and visualization. The complexity of these processing steps is a major obstacle for many potential users in science and practice. Adequate tools are available either only at significant costs with no access to the uncerlying source code, or they are incomplete, insufficiently documented and intransparent. The wradlib project has been initiated in order to lower the barrier for potential users of weather radar data in the geosciences and to provide a common platform for research on new algorithms. wradlib is an open source library for the full range of weather radar related processing algorithms, which is well documented and easy to use. The main parts of the library are currently implemented in the python programming language. Python is well known both for its ease of use as well as its ability to integrate code written in other programming languages like Fortran or C/C++. The well established Numpy and Scipy packages are used to provide decent performance for pure Python implementations of algorithms. We welcome contributions written in any computer language and will try to make them accessible from Python. We would like to present the current state of this library together with a few showcase examples.

Heistermann, M.; Pfaff, Th.; Jacobi, S.

2012-04-01

45

Use of weather radar for flood forecasting in the Sieve River Basin: A sensitivity analysis  

SciTech Connect

Weather radar, in combination with a distributed rainfall-runoff model, promises to significantly improve real-time flood forecasting. This paper investigates the value of radar-derived precipitation in forecasting streamflow in the Sieve River basin, near Florence, Italy. The basin is modeled with a distributed rainfall-runoff model that exploits topographic information available from digital elevation maps. The sensitivity of the flood forecast to various properties of the radar-derived rainfall is studied. It is found that use of the proper radar reflectivity-rainfall intensity (Z-R) relationship is the most crucial factor in obtaining correct flood hydrographs. Errors resulting from spatially averaging radar rainfall are acceptable, but the use of discrete point information (i.e. raingage) can lead to serious problems. Reducing the resolution of the 5-min radar signal by temporally averaging over 15 and 30 min does not lead to major errors. Using 3-bit radar data (rather than the usual 8-bit data) to represent intensities results in significant operational savings without serious problems in hydrograph accuracy. 24 refs., 28 figs., 2 tabs.

Pessoa, M.L.; Bras, R.L.; Williams, E.R. (Massachusetts Inst. of Technology, Cambridge (United States))

1993-03-01

46

Two methods of ambiguity resolution in pulse Doppler weather radars  

Microsoft Academic Search

A comparison is made of the performance of a weather Doppler radar with a staggered pulse repetition time and a radar with a random (but known) phase. As a standard for this comparison, the specifications of the forthcoming next generation weather radar (NEXRAD) are used. A statistical analysis of the spectral moment estimates for the staggered scheme is developed, and

D. S. Zrnic; Pravas Mahapatra

1985-01-01

47

Statistical evaluation of a radar rainfall system for sewer system management  

NASA Astrophysics Data System (ADS)

Urban areas are faced with mounting demands for managing waste and stormwater for a cleaner environment. Rainfall information is a critical component in efficient management of urban drainage systems. A major water quality impact affecting receiving waterbodies is the discharge of untreated waste and stormwater during precipitation, termed wet weather flow. Elimination or reduction of wet weather flow in metropolitan sewer districts is a major goal of environmental protection agencies and often requires considerable capital improvements. Design of these improvements requires accurate rainfall data in conjunction with monitored wastewater flow data. Characterizing the hydrologic/hydraulic performance of the sewer using distant rain gauges can cause oversizing and wasted expenditures. Advanced technology has improved our ability to measure accurately rainfall over large areas. Weather radar, when combined with rain gauge measurements, provides detailed information concerning rainfall intensities over specific watersheds. Knowing how much rain fell over contributing areas during specific periods aids in characterizing inflow and infiltration to sanitary and combined sewers, calibration of sewer system models, and in operation of predictive real-time control measures. Described herein is the design of a system for managing rainfall information for sewer system management, along with statistical analysis of 60 events from a large metropolitan sewer district. Analysis of the lower quartile rainfall events indicates that the expected average difference is 25.61%. Upper quartile rainfall events have an expected average difference of 17.25%. Rain gauge and radar accumulations are compared and evaluated in relation to specific needs of an urban application. Overall, the events analyzed agree to within ± 8% based on the median average difference between gauge and radar.

Vieux, B. E.; Vieux, J. E.

2005-09-01

48

Uncertainty in radar-rainfall composite and its impact on hydrologic prediction for the eastern Iowa flood of 2008  

NASA Astrophysics Data System (ADS)

This study addresses a significant potential source of error that exists in radar-rainfall maps that are combined using data from multiple WSR-88D radars of the Next Generation Radar (NEXRAD) national network in the United States. This error stems from different radar calibration offsets that create a border within discontinuous rainfall fields at the equidistance zone among radars. The discontinuity in rainfall fields could lead to misestimation of rainfall over basins and subsequently, to significant errors in streamflow predictions through a hydrologic model. In this study, we produce enhanced radar-rainfall estimates (HN3) based on a novel approach that allows us to reduce the effects of the relative radar calibration bias. We use the relative bias information previously presented in a radar reflectivity comparison study. To investigate the effects of the relative bias adjustment, we evaluate the HN3 and Stage IV radar-rainfall by comparing them with rain gauge data and analyzing their ability to simulate streamflow for an extreme flood case. While the HN3 estimates are statistically comparable to the Stage IV estimates in the rain gauge data comparison, the borderline that identifies discontinuous rainfall fields disappears in the HN3 estimates. We performed hydrological simulations using a physically based, data-intensive, calibration-free, hillslope-link hydrologic model called CUENCAS and demonstrated CUENCAS's ability to accurately simulate flows by comparing results with observed and predicted streamflow generated by the Sacramento (SAC) model. SAC is the operational flood forecast model that has been used by the National Weather Service since 1969, and it was extensively calibrated based on historical data. The simulation results show that the adjustment improves streamflow predictions in the regions where the misestimation of rainfall quantity is considerable. We conclude that systematic error arising from different calibration offsets in rainfall fields can significantly affect hydrologic predictions.

Seo, Bong-Chul; Cunha, Luciana K.; Krajewski, Witold F.

2013-05-01

49

Simulation of radar rainfall errors and their propagation into rainfall-runoff processes  

NASA Astrophysics Data System (ADS)

Radar rainfall data compared with rain gauge measurements provide higher spatial and temporal resolution. However, radar data obtained form reflectivity patterns are subject to various errors such as errors in Z-R relationship, vertical profile of reflectivity, spatial and temporal sampling, etc. Characterization of such uncertainties in radar data and their effects on hydrologic simulations (e.g., streamflow estimation) is a challenging issue. This study aims to analyze radar rainfall error characteristics empirically to gain information on prosperities of random error representativeness and its temporal and spatial dependency. To empirically analyze error characteristics, high resolution and accurate rain gauge measurements are required. The Goodwin Creek watershed located in the north part of Mississippi is selected for this study due to availability of a dense rain gauge network. A total of 30 rain gauge measurement stations within Goodwin Creak watershed and the NWS Level II radar reflectivity data obtained from the WSR-88dD Memphis radar station with temporal resolution of 5min and spatial resolution of 1 km2 are used in this study. Radar data and rain gauge measurements comparisons are used to estimate overall bias, and statistical characteristics and spatio-temporal dependency of radar rainfall error fields. This information is then used to simulate realizations of radar error patterns with multiple correlated variables using Monte Calro method and the Cholesky decomposition. The generated error fields are then imposed on radar rainfall fields to obtain statistical realizations of input rainfall fields. Each simulated realization is then fed as input to a distributed physically based hydrological model resulting in an ensemble of predicted runoff hydrographs. The study analyzes the propagation of radar errors on the simulation of different rainfall-runoff processes such as streamflow, soil moisture, infiltration, and over-land flooding.

Aghakouchak, A.; Habib, E.

2008-05-01

50

Detecting Extreme Weather at Outermost Radar Ranges  

NASA Astrophysics Data System (ADS)

Since the inception (1974) of the Bauru weather radar project in Central São Paulo, Brazil (22o 21' 49o 01') the upper portion of intense storms were routinely detected at the longest radar ranges. Calheiros in1975 compiled echoes in the 320-400 km range from the Bauru radar distributed in the azimuthal sector from about 85o to 210o CCW (the remaining interval of azimuths was plagued by partial beam blockage. Due to data availability at the time, the study did not include any event from summer when intense convection takes place. Notwithstanding, most of the registered echoes were from the month of October of 1974, in the period of transition from dry-to-wet conditions, when intense storms, which can reach considerable heights, occur. In the conclusions of the study, the issue of exploring the radar capability to detect severe weather at the longest ranges in order to reduce the number of sets required for a given coverage was already considered. In 1992 when a new S-band Doppler radar substituted for the old C-band the detection at the outermost range intervals was substantially improved. This prompted more recently as potential benefits increased development of efforts to extend the useful range of the Bauru radar to provide indications of precipitations intensities beyond the nominal coverage of 240 km were the quantification is performed. A procedure was then devised by Machado and Calheiros, to retrieve the gross structure of radar cells at far ranges and derive an indication of the precipitation intensity. At those ranges only the upper portion of the core of intense cells will be detected. Basically, the procedure consists in correcting the reflectivity measured by the radar using statistical techniques and then surrounding the detected core with satellite imagery in the MW and IR bands. The combination of the corrected core intensity with the gross features of the cells structure will be tested as the indicator of exceptionally severe weather conditions. This paper presents the statistics of reflectivity distributions at the 400 to 450 km range interval, stratified in 10 km rings, i.e., 400-410, 410-420, 420-430, 430-440 and 440-450 km. Statistics are computed for each year, from 2000 to 2004, and for each month from January to March in each year. In general, for the three-month period and all years taken as a whole, most of the reflectivities are limited to 30-35 dBZ for all range rings. Analysing by month, January and February show higher reflectivities when compared to March, as expected from the relative summer activity for each month. For the 430-440 km and the 440-450 km rings there are very few cases of reflectivities above 30 dBZ, while for the first three rings this number is substantially higher, although still quite small compared to the whole number of echoes. This result indicates that events for the two last rings, and reflectivities above 30 dBZ, should be the first to be investigated in search for extreme severity. In this sense, one intense storm at about 100-150 km from the radar was selected as example of exceptional weather conditions. It was from 19 February 2005 and presented particularly severe features. Its position at maximum development was within mid radar range (approximately 100-130 km). Reflectivities exceeded 50 dBZ for more than two hours, and values of 15 dBZ were detected above a height of 19 km, showing deep penetration into the stratosphere (tropopause was around 16 km). This storm is a good example of a particularly severe storm which would be detected in the far radar range.

Calheiros, R. V.; Antonio, C. A.

2006-12-01

51

Using probabilistic radar rainfall nowcasts and NWP forecasts for flow prediction in urban catchments  

NASA Astrophysics Data System (ADS)

The use of Quantitative Precipitation Forecasts (QPFs) to model run-off and flow processes in urban areas is a challenging problem, as rainfall data with high spatial and temporal resolutions are required. Many attempts have been made to use weather radar to produce rainfall forecasts with lead times of a few hours ahead.The UK Met Office in collaboration with the Australian Bureau of Meteorology has developed a stochastic probabilistic precipitation forecasting scheme (STEPS), which merges an extrapolation radar rainfall forecast with a high-resolution Numerical Weather Prediction (NWP) rainfall forecast. This paper assesses the application of this model in a small urban area (town of Yorkshire). Three precipitation events that occurred during 2007 and 2008 with different meteorological characteristics were simulated. The STEPS model was used to produce both deterministic and ensemble precipitation forecasts with spatial and temporal scales of 2 km and 15 min respectively and 6-hour lead time. The precipitation forecasts were coupled to an Infoworks CSmodel of the sewer system of a town in Yorkshire to produce flow predictions. The simulated precipitation events were analyzed in terms of rainfall and flow predictions at the urban scale of the study area.The results show that the overall performance of the rainfall forecasting system decreases with increasing rainfall intensities, and that the ensemble rainfall forecasts have a higher skill than the deterministic forecasts in predicting lower rainfall intensities. The results also show that stratiform precipitation is forecasted better than convective precipitation.More events need to be evaluated in order to define whether ensemble rainfall forecasts improve flow predictions on the urban scale and the analysis in terms of flow at this stage only supports a potential application for qualitative flood warnings in the small urban catchment considered.

Liguori, S.; Rico-Ramirez, M. A.; Schellart, A. N. A.; Saul, A. J.

2012-01-01

52

Towards a roadmap for use of radar rainfall data in urban drainage  

Microsoft Academic Search

Radar rainfall has received growing attention in the urban drainage community since its first appearance on an Urban Storm Drainage Conference in 1984. Still, operational applications of radar rainfall in urban hydrology is limited. The following aspects have to be considered for radar rainfall data use specifically in urban hydrology: the type of the radar, the application requirements on the

Thomas Einfalt; Karsten Arnbjerg-Nielsen; Claudia Golz; Niels-Einar Jensen; Markus Quirmbach; Guido Vaes; Baxter Vieux

2004-01-01

53

Sensitivity Studies of the Radar-Rainfall Error Models  

NASA Astrophysics Data System (ADS)

It is well acknowledged that there are large uncertainties associated with the operational quantitative precipitation estimates produced by the U.S. national network of WSR-88D radars. These errors are due to the measurement principles, parameter estimation, and not fully understood physical processes. Comprehensive quantitative evaluation of these uncertainties is still at an early stage. The authors proposed an empirically-based model in which the relation between true rainfall (RA) and radar-rainfall (RR) could be described as the product of a deterministic distortion function and a random component. However, how different values of the parameters in the radar-rainfall algorithms used to create these products impact the model results still remains an open question. In this study, the authors investigate the effects of different exponents in the Z-R relation (Marshall- Palmer, NEXRAD, and tropical) and of an anomalous propagation (AP) removal algorithm. Additionally, they generalize the model to describe the radar-rainfall uncertainties in the additive form. This approach is fully empirically based and rain gauge estimates are considered as an approximation of the true rainfall. The proposed results are based on a large sample (six years) of data from the Oklahoma City radar (KTLX) and processed through the Hydro-NEXRAD software system. The radar data are complemented with the corresponding rain gauge observations from the Oklahoma Mesonet, and the Agricultural Research Service Micronet.

Villarini, G.; Krajewski, W. F.; Ciach, G. J.

2007-12-01

54

Terrain and Weather Effects on Doppler Radar Navigation Systems.  

National Technical Information Service (NTIS)

The effects of terrain and weather conditions upon airborne doppler radar performance are described. The extensive flight test data compiled by military and commercial users of the doppler radar and theoretical knowledge of propagation and scattering theo...

E. Laskowski

1964-01-01

55

SUBPIXEL-SCALE RAINFALL VARIABILITY AND THE EFFECTS ON SEPARATION OF RADAR AND GAUGE RAINFALL ERRORS  

EPA Science Inventory

One of the primary sources of the discrepancies between radar-based rainfall estimates and rain gauge measurements is the point-area difference, i.e., the intrinsic difference in the spatial dimensions of the rainfall fields that the respective data sets are meant to represent. ...

56

Radar Analyses of Space-Time Variability of Extreme Flood-Producing Rainfall in Urban Drainage Basins  

NASA Astrophysics Data System (ADS)

The Charlotte, North Carolina metropolitan area has experienced extensive urban and suburban growth during the past 40 years, resulting in increasing flood hazards in the region. Record flooding in the urban core of Charlotte occurred on 23 July 1997 from a storm that produced rainfall accumulations of more than 250 mm during an 18 hour period, more than doubling the 24 hour rainfall maximum in Charlotte, and causing 60 million in property damage and three fatalities. Analyses of the 23 July 1997 storm and flood are based on rainfall and discharge observations from dense networks of rain gages and stream gages maintained by the U.S. Geological Survey and rainfall estimates from two WSR-88D weather radars, both located approximately 100 km from the urban core of Charlotte. This wealth of observations provides an opportunity to address hydrometeorological questions concerning: (1) the accuracy of radar rainfall estimates for extreme, flood-producing rainfall; (2) the space-time variability of extreme, flood-producing rainfall in urban environments; and (3) the effects of urbanization on extreme flood response in urban environments. It is shown that bias-corrected radar rainfall estimates for the 23 July 1997 storm are quite accurate and provide the capability for resolving the fundamental rainfall forcing associated with regional variation in extreme flood response. This study shows how the spatial and temporal variability of rainfall combines with the land surface properties to determine extreme flood response in urban drainage basins.

Villarini, G.; Smith, J. A.; Baeck, M. L.; Sturdevant-Rees, P.; Krajewski, W. F.

2009-04-01

57

Radar Signatures for Severe Convective Weather  

NSDL National Science Digital Library

This resource is intended for use as a job aid by operational weather forecasters in live warning situations and as a reference tool to better understand some aspects of severe thunderstorm warning events. Thumbnail images show typical representatives for sixteen radar reflectivity and velocity signatures as well as three primary severe storm types. Each signature links to content describing detection techniques and conceptual and diagnostic information to help determine storm severity. The majority of the examples shown are southern hemisphere storms in Australia; examples from the northern hemisphere are noted.

Guarente, Bryan; Muller, Bruce

2003-08-01

58

Weather radar to prevent air crashes  

NASA Astrophysics Data System (ADS)

An operational demonstration of Terminal Doppler Weather Radar (TDWR) at Stapleton International Airport, Denver, finishes August 31. For 2 months, TDWR has been used to detect wind shear and other hazardous weather around air terminals and to provide warnings to air traffic controllers and pilots in time to avert accidents.The biggest hazard for aircraft approaching or departing terminals is the microburst, a form of wind shear. Microbursts are produced by a small-scale, powerful downdraft of cold, heavy air occurring beneath a thunderstorm, rain shower, or cumulus cloud. As the downdraft reaches Earth's surface, it spreads out horizontally (see Figure 1). An aircraft flying through a microburst at low-altitude encounters a strong headwind, then a downdraft, and finally a tailwind that causes a sharp reduction in speed and loss of lift. This deadly sequence of events has caused at least 30 accidents and 500 deaths in the United States since the mid-1960s.

Bush, Susan M.

59

Estimation of Radar-Rainfall Error Spatial Correlation  

NASA Astrophysics Data System (ADS)

The authors present a study of a theoretical framework to estimate the radar-rainfall error spatial correlation using high density rain gauge networks and high quality data. The error is defined as the difference between the radar estimate and the true areal rainfall. Based on the framework of second-order rainfall field characterization, the authors propose a method for error spatial correlation estimation which is an extension of the error variance separation that uses radar data at the rain gauge locations and accounts for gauge spatial representativeness error. To assess the performance of the method, the authors carry out a Monte Carlo simulation experiment, where the method is applied on simulated radar-rainfall fields with known error spatial correlation structure. The results show that the method performs very well. The authors also demonstrate the necessity to consider the gauge representativeness error while estimating the error correlation structure. This requires information from a very dense network, limiting applicability of the approach. To illustrate practical value of the method the authors applied it to the NEXRAD Hourly Digital Product (HDP) and Iowa Daily Erosion Project's rainfall products. The corresponding dense rain gauge networks are Oklahoma Micronet and the IIHR's network around Iowa City, Iowa.

Mandapaka, P. V.; Krajewski, W. F.; Ciach, G.; Villarini, G.

2006-12-01

60

Evaluation of the new French operational weather radar product for the field of urban hydrology  

NASA Astrophysics Data System (ADS)

The main objective of this paper is to evaluate, at the urban scale, the accuracy of the new French operational radar processing chain deployed within the French operational weather radar network. Such an evaluation is conducted by comparing radar data resulting from this processing chain (with a 1-km 2 resolution) to rain gauge data at four different time scales, i.e. 5, 15, 30 and 60 min. These data are supplied by the Trappes Radar Station, located 30 km southwest of Paris. A total of 69 rain gauges installed within a radius of 80 km from the weather radar have provided the ground reference data. The dataset comprises 50 varied rainy days. The influence of distance, quality code of the radar data and type of rainfall, as well as the adjustment factor, is analyzed. The present analysis moreover seeks to evaluate the error specific to reference data by considering instrumental and representativeness errors, for the purpose of taking reference data accuracy into account in the radar/rain gauge comparison. This study shows that radar data obtained by means of this new operational radar processing chain are not yet reliable enough for direct use in quantitative applications within the field of urban hydrology.

Emmanuel, I.; Andrieu, H.; Tabary, P.

2012-01-01

61

Propagation of radar rainfall uncertainty in urban flood simulations  

NASA Astrophysics Data System (ADS)

This work discusses the results of the implementation of a novel probabilistic system designed to improve ensemble sewer flow predictions for the drainage network of a small urban area in the North of England. The probabilistic system has been developed to model the uncertainty associated to radar rainfall estimates and propagate it through radar-based ensemble sewer flow predictions. The assessment of this system aims at outlining the benefits of addressing the uncertainty associated to radar rainfall estimates in a probabilistic framework, to be potentially implemented in the real-time management of the sewer network in the study area. Radar rainfall estimates are affected by uncertainty due to various factors [1-3] and quality control and correction techniques have been developed in order to improve their accuracy. However, the hydrological use of radar rainfall estimates and forecasts remains challenging. A significant effort has been devoted by the international research community to the assessment of the uncertainty propagation through probabilistic hydro-meteorological forecast systems [4-5], and various approaches have been implemented for the purpose of characterizing the uncertainty in radar rainfall estimates and forecasts [6-11]. A radar-based ensemble stochastic approach, similar to the one implemented for use in the Southern-Alps by the REAL system [6], has been developed for the purpose of this work. An ensemble generator has been calibrated on the basis of the spatial-temporal characteristics of the residual error in radar estimates assessed with reference to rainfall records from around 200 rain gauges available for the year 2007, previously post-processed and corrected by the UK Met Office [12-13]. Each ensemble member is determined by summing a perturbation field to the unperturbed radar rainfall field. The perturbations are generated by imposing the radar error spatial and temporal correlation structure to purely stochastic fields. A hydrodynamic sewer network model implemented in the Infoworks software was used to model the rainfall-runoff process in the urban area. The software calculates the flow through the sewer conduits of the urban model using rainfall as the primary input. The sewer network is covered by 25 radar pixels with a spatial resolution of 1 km2. The majority of the sewer system is combined, carrying both urban rainfall runoff as well as domestic and trade waste water [11]. The urban model was configured to receive the probabilistic radar rainfall fields. The results showed that the radar rainfall ensembles provide additional information about the uncertainty in the radar rainfall measurements that can be propagated in urban flood modelling. The peaks of the measured flow hydrographs are often bounded within the uncertainty area produced by using the radar rainfall ensembles. This is in fact one of the benefits of using radar rainfall ensembles in urban flood modelling. More work needs to be done in improving the urban models, but this is out of the scope of this research. The rainfall uncertainty cannot explain the whole uncertainty shown in the flow simulations, and additional sources of uncertainty will come from the structure of the urban models as well as the large number of parameters required by these models. Acknowledgements The authors would like to acknowledge the BADC, the UK Met Office and the UK Environment Agency for providing the various data sets. We also thank Yorkshire Water Services Ltd for providing the urban model. The authors acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) via grant EP/I012222/1. References [1] Browning KA, 1978. Meteorological applications of radar. Reports on Progress in Physics 41 761 Doi: 10.1088/0034-4885/41/5/003 [2] Rico-Ramirez MA, Cluckie ID, Shepherd G, Pallot A, 2007. A high-resolution radar experiment on the island of Jersey. Meteorological Applications 14: 117-129. [3] Villarini G, Krajewski WF, 2010. Review of the different sources of uncertainty in single polarization radar-based estimate

Liguori, Sara; Rico-Ramirez, Miguel

2013-04-01

62

Use of a weather radar for the hydrology of a mountainous area. Part I: radar measurement interpretation  

NASA Astrophysics Data System (ADS)

This paper addresses rainfall radar measurement in mountainous areas where numerous catchments subject to flash flooding are located. The main sources of error affecting the quantitative use of weather radar data are examined with special attention paid to the influence of topography and altitude. A radar in a mountainous region is affected by specific measurement errors such as beam blockage; other sources of error like bright band interception can be enhanced by the effect of altitude. This work is based on data collected during the 86-88 Cévennes Experiment conducted in a mountainous Mediterranean region in the south of France prone to flash floods. Analysis of the main sources of error leads to the following observations. Beam blockage can be corrected using digital terrain models with the correction efficiency depending on the accuracy of the radar antenna pointing direction. The influence of vertical variations in radar reflectivity is shown to be taken into account at an hourly time step in order to provide satisfactory range-dependent corrections. Additionally, the control of the stability of the radar signal using strong ground clutter is described. Because of attenuation effects, the use of a 10-cm wavelength is recommended for surveying intense rain events which regularly affect Mediterranean regions. The error due to an unadapted Z-R relationship is shown to depend on the statistical distribution of reflectivity over the catchment where the rainfall measurement is utilized.

Andrieu, H.; Creutin, J. D.; Delrieu, G.; Faure, D.

1997-06-01

63

Reconfigurable data acquisition system for weather radar applications  

Microsoft Academic Search

Tornado, hazardous weather and flood detection radars demand high-throughput, high-speed data acquisition and processing. Weather-processing systems need to be capable of implementing powerful signal processing algorithms on the raw data collected by the radars. Following processing, data is distributed to the end-user in real-time for timely and accurate detection of imminent weather disasters. Since physical accessibility to such systems is

Rishi Khasgiwale; Luko Krnan; Atchuthan Perinkulam; Russell Tessier

2005-01-01

64

Quality Assessment of Weather Radar Wind Profiles during Bird Migration  

Microsoft Academic Search

Wind profiles from an operational C-band Doppler radar have been combined with data from a bird tracking radar to assess the wind profile quality during bird migration. The weather radar wind profiles (WRWPs) are retrieved using the well-known volume velocity processing (VVP) technique. The X-band bird radar performed range-height scans perpendicular to the main migration direction and bird densities were

Iwan Holleman; Hans van Gasteren; Willem Bouten

2008-01-01

65

Improving the accuracy of the radar rainfall estimates using gage adjustment techniques: Case study for west Anatolia, Turkey  

NASA Astrophysics Data System (ADS)

In this work, Balikesir (a city in west Anatolia, Turkey), meteorological weather radar rainfall measurements are statistically analyzed and adjusted by using a network of automatic raingage (AWOS). To improve the accuracy of rainfall measurements of the Balikesir weather radar, a statistical analysis is performed by considering 16 operational raingages among 20 within the circular area with a radius of 120 km, the center being at the radar site. Firstly, the assessment factor (AF), which is the ratio of the overall total rainfall amount ( R) calculated by radar to the overall total rainfall amount ( G) measured at the raingage in a selected time period, is obtained for the coordinates of each raingage on the radar image. The regression coefficients are determined from AF regression equation by means of a weighted multiple regression technique using spatial variables which are taken to be the distance between radar and raingage ( D), the topographical height of raingage (HG) and the minimum height above the raingage that the target is visible from the radar (HV min). To improve the radar rainfall in all 720 × 720 pixel in a radar image, approximate HV min values are determined for some areas on a radar image after their exact values have been found for the raingage points. Finally, a new radar product called SCR (Statistically Corrected Rain), which can be run operationally on radar software, is developed by the authors. Within the 48-h period of rainfall, the observed total amount at the raingage is obtained as 803.80 mm (50.24 mm average), while radar estimated 314.00 mm (19.63 mm average), indicating an absolute mean error of 30.61 mm. With the analysis used in this paper, the absolute mean error is reduced to 16.46 mm and RMSE is reduced from 36.04 to 18.78 mm. The overall assessment of the whole analysis in comparison with the existing literature, possible drawbacks and their causes are given in the conclusion part.

Öztürk, Kurtulu?; Y?lmazer, Ali Ulvi

2007-11-01

66

Mesoscale Structure of the Heavy Rainfall in Chuzhou in August 2008 by Dual-radar  

NASA Astrophysics Data System (ADS)

Due to the effect of the low-pressure system of Fung-Wong and the cold air, it produced a heavy precipitation in the east region of Anhui province in China, up to 429mm rainfall in Chuzhou and 414mm in Quanjiao from 0800 LST 1 August to 0800 LST 2 August 2008. It is a local, sudden and short time heavy rain. The three dimensional wind fields were retrieved by the volume scan data of the dual-Doppler radar located in Nanjing and Maanshan cities. The evolution of the 3D wind fields and the formation mechanism of the sudden heavy rainfall were investigated. It is a convective cloud precipitation based on the radar echo analyses. The meso-?-scale convective system (M?CS) and the meso-?-scale system located on the M?CS played an important role on this heavy rainfall. The meso-?-scale convective cloud has high precipitation efficiency. The dual-Doppler retrieved wind reveals that the heavy rainfall was caused by the meso-?-scale shear line and the meso-?-scale convergence lines at the low and the medium levels. The shear line spread from west to east. It stayed on the Chuzhou and Quanjiao area for period of time. The shear line triggered and maintained the heavy rainfall. On the other hand, the plentiful water vapour was transported to the rainfall area continuously. These factors greadtly availed to the heavy rainfall. There were strong convergence and vorticity at the low and medium levels of the M?CS. When the shear line at the low and medium levels moved out of the rainfall area, the precipitation began to weak remarkably too. Acknowlegements The work was supported by the National Science Foundation of China (grant 40605014, 40975015) and the foundation of state key laboratory of severe weather(2008LASWZI01).

Haiguang, Zhou

2010-05-01

67

Sensitivity of Flow Uncertainty to Radar Rainfall Uncertainty in the Context of Operational Distributed Hydrologic Modeling  

NASA Astrophysics Data System (ADS)

The current study focuses on the sensitivity of distributed model flow forecast uncertainty to the uncertainty in the radar rainfall input. Various studies estimate a 30 to 100% uncertainty in radar rainfall estimates from the operational NEXRAD radars. This study addresses the following questions: How does this uncertainty in rainfall input impact the flow simulations produced by a hydrologic model? How does this effect compare to the uncertainty in flow forecasts resulting from initial condition and model parametric uncertainty? The hydrologic model used, HRCDHM, is a catchment-based, distributed hydrologic model and accepts hourly precipitation input from the operational WSR-88D weather radar. A GIS is used to process digital terrain data, delineate sub-catchments of a given large watershed, and supply sub-catchment characteristics (subbasin area, stream length, stream slope and channel-network topology) to the hydrologic model components. HRCDHM uses an adaptation of the U.S. NWS operational Sacramento soil moisture accounting model to produce runoff for each sub-catchment within the larger study watershed. Kinematic or Muskingum-Cunge channel routing is implemented to combine and route sub-catchment flows through the channel network. Available spatial soils information is used to vary hydrologic model parameters from sub-catchment to sub-catchment. HRCDHM was applied to the 2,500 km2 Illinois River watershed in Arkansas and Oklahoma with outlet at Tahlequah, Oklahoma. The watershed is under the coverage of the operational WSR-88D radar at Tulsa, Oklahoma. For distributed modeling, the watershed area has been subdivided into sub-catchments with an average area of 80km2. Flow simulations are validated at various gauged locations within the watershed. A Monte Carlo framework was used to assess the sensitivity of the simulated flows to uncertainty in radar input for different radar error distributions (uniform or exponential), and to make comparisons to the flow sensitivity under parametric input uncertainty. Initial results indicate that (a) the distributed model reproduces well the hourly observed flows at the gauged sites, (b) flow sensitivity to radar input uncertainty is scale dependent, and (c) the sensitivity of the range of simulated flows to the expected uncertainty in certain hydrologic parameters is comparable to that resulting from the expected uncertainty in radar rainfall input

Carpenter, T. M.; Georgakakos, K. P.; Georgakakos, K. P.

2001-12-01

68

Introducing uncertainty of radar-rainfall estimates to the verification of mesoscale model precipitation forecasts  

NASA Astrophysics Data System (ADS)

A simple measure of the uncertainty associated with using radar-derived rainfall estimates as "truth" has been introduced to the Numerical Weather Prediction (NWP) verification process to assess the effect on forecast skill and errors. Deterministic precipitation forecasts from the mesoscale version of the UK Met Office Unified Model for a two-day high-impact event and for a month were verified at the daily and six-hourly time scale using a spatially-based intensity-scale method and various traditional skill scores such as the Equitable Threat Score (ETS) and log-odds ratio. Radar-rainfall accumulations from the UK Nimrod radar-composite were used. The results show that the inclusion of uncertainty has some effect, shifting the forecast errors and skill. The study also allowed for the comparison of results from the intensity-scale method and traditional skill scores. It showed that the two methods complement each other, one detailing the scale and rainfall accumulation thresholds where the errors occur, the other showing how skillful the forecast is. It was also found that for the six-hourly forecasts the error distributions remain similar with forecast lead time but skill decreases. This highlights the difference between forecast error and forecast skill, and that they are not necessarily the same.

Mittermaier, M. P.

2008-05-01

69

Radar rainfall estimation as a support for the hydro-meteorological analysis of debris flow and flash flood events  

NASA Astrophysics Data System (ADS)

This work is dedicated to radar rainfall estimation for the post-event analysis of four debris flows/flash flood events which impacted the Upper Adige river system, in the Central Italian Alps with high rainfall amounts and causing damages to people and to the road system. The storm events were observed by means of a C-band weather radar system and a rain gauge network enabling the validation of radar rainfall amount estimates with fine time resolution. For these contrasted rainy system with convective and stratiform regions, the combination of the vertical (VPR) and radial (attenuation, screening) sources of heterogeneity yields a very challenging problem for radar quantitative precipitation estimation at C-band. Results obtained by applying a number of corrections to radar reflectivity measures are described. Particular attention is paid on application of the mountain reference technique on signal attenuation, screening and vertical profile of radar reflectivity. Signal attenuation is corrected for by using the Mountain Reference Technique. The worth of using the Mountain Reference Technique is demonstrated to quantify rain attenuation effects that affect C-band radar measurements in heavy rain. Screening effects were quantified using a geometrical calculation based on a digitized terrain model of the region. The vertical structure of the reflectivity was modelled with a normalized apparent vertical profile of reflectivity. The spatial structure of the rainstorms is examined over various temporal aggregations. The rain estimates are used to assess the rain amount and intensities over the small catchments were debris flows were triggered.

Marra, F.; Nikolopoulos, E.

2012-04-01

70

Nowcasting for a high-resolution weather radar network  

Microsoft Academic Search

Short-term prediction (nowcasting) of high-impact weather events can lead to significant improvement in warnings and advisories and is of great practical importance. Nowcasting using weather radar reflectivity data has been shown to be particularly useful. The Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network provides high-resolution reflectivity data amenable to producing valuable nowcasts. The high-resolution nature of CASA data

Evan Ruzanski

2010-01-01

71

Airport radar monitoring of wake vortex in all weather conditions  

Microsoft Academic Search

To assess maturity and capability of X-band radars to monitor wake roll-ups in all weather conditions, Radar data were collected on airports, near runway at ORLY airport and just under its ILS Interception Area. Additional trials took place on Paris-CDG Airport to benchmark Lidar & Radar Technologies. Continuous Detection, characterization and profiling capabilities of wake vortices, up to a range

Frédéric Barbaresco

2010-01-01

72

Terminal Doppler weather radar operational test and evaluation, Orlando 1990  

Microsoft Academic Search

Lincoln Laboratory conducted an evaluation of the Federal Aviation Administration (FAA) Terminal Doppler Weather Radar (TDWR) system in Orlando, Florida during the summer of 1990. In previous years, evaluations have been conducted at airports in Kansas City, MO (1989) and Denver, CO (1988). Since the testing at the Kansas City International Airport, the radar was modified to operate in C-band,

David M. Bernella

1991-01-01

73

Investigation of Electromagnetic Radiation from High Power Weather Radar  

Microsoft Academic Search

In this paper, we devote to investigate the electromagnetic (EM) radiation characteristics and radiation intensity of high power weather radar once extensively. We compare our field measurement with international specifications and an operating early-warning radar case study also made a contribution to those who are interested in the healthy effect of high power EM radiation. The measured data is much

Jiun-Yu Wen; Jhin-Fang Huang

2009-01-01

74

Terminal Doppler weather radar (TDWR) coverage of satellite airports  

Microsoft Academic Search

The Federal Aviation Administration's (FAA) Terminal Doppler Weather Radar (TDWR) system detects and reports hazardous weather in and around airport terminal approach and departure zones. The TDWR identifies and warns air traffic controllers (ATCs) of low altitude wind shear hazards caused by microbursts and gust fronts, in addition to reporting on precipitation intensities and providing advanced warning of wind shifts.

A. S. Barry

2000-01-01

75

Flash-flood early warning using weather radar data: from nowcasting to forecasting  

NASA Astrophysics Data System (ADS)

This study explores the limits of radar-based forecasting for hydrological runoff prediction. Two novel probabilistic radar-based forecasting chains for flash-flood early warning are investigated in three catchments in the Southern Swiss Alps and set in relation to deterministic discharge forecast for the same catchments. The first probabilistic radar-based forecasting chain is driven by NORA (Nowcasting of Orographic Rainfall by means of Analogues), an analogue-based heuristic nowcasting system to predict orographic rainfall for the following eight hours. The second probabilistic forecasting system evaluated is REAL-C2, where the numerical weather prediction COSMO-2 is initialized with 25 different initial conditions derived from a four-day nowcast with the radar ensemble REAL. Additionally, three deterministic forecasting chains were analysed. The performance of these five flash-flood forecasting systems was analysed for 1389 h between June 2007 and December 2010 for which NORA forecasts were issued, due to the presence of orographic forcing. We found a clear preference for the probabilistic approach. Discharge forecasts perform better when forced by NORA rather than by a persistent radar QPE for lead times up to eight hours and for all discharge thresholds analysed. The best results were, however, obtained with the REAL-C2 forecasting chain, which was also remarkably skilful even with the highest thresholds. However, for regions where REAL cannot be produced, NORA might be an option for forecasting events triggered by orographic precipitation.

Liechti, K.; Panziera, L.; Germann, U.; Zappa, M.

2013-01-01

76

Flash-flood early warning using weather radar data: from nowcasting to forecasting  

NASA Astrophysics Data System (ADS)

In our study we explore the limits of radar-based forecasting for hydrological runoff prediction. Two novel probabilistic radar-based forecasting chains for flash-flood early warning are investigated in three catchments in the Southern Swiss Alps and set in relation to deterministic discharge forecast for the same catchments. The first probabilistic radar-based forecasting chain is driven by NORA (Nowcasting of Orographic Rainfall by means of Analogues), an analogue-based heuristic nowcasting system to predict orographic rainfall for the following eight hours. The second probabilistic forecasting system evaluated is REAL-C2, where the numerical weather prediction COSMO-2 is initialized with 25 different initial conditions derived from a four-day nowcast with the radar ensemble REAL. Additionally, three deterministic forecasting chains were analysed. The performance of these five flash-flood forecasting systems was analysed for 1389 hours between June 2007 and December 2010 for which NORA forecasts were issued, due to the presence of orographic forcing. We found a clear preference for the probabilistic approach. Discharge forecasts perform better when forced by NORA rather than by a persistent radar QPE for lead times up to eight hours and for all discharge thresholds analysed. The best results were, however, obtained with the REAL-C2 forecasting chain, which was also remarkably skilful even with the highest thresholds. However, for regions where REAL cannot be produced, NORA might be an option for forecasting events triggered by orographic forcing.

Liechti, Katharina; Panziera, Luca; Germann, Urs; Zappa, Massimiliano

2013-04-01

77

Mapping Wintering Waterfowl Distributions Using Weather Surveillance Radar  

PubMed Central

The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998–1999 and 1999–2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of ?5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998–1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents.

Buler, Jeffrey J.; Randall, Lori A.; Fleskes, Joseph P.; Barrow, Wylie C.; Bogart, Tianna; Kluver, Daria

2012-01-01

78

Gaussian model adaptive time domain filter (GMAT) for weather radars  

Microsoft Academic Search

This paper presents an adaptive time domain filter for ground clutter filtering and signal parameter estimation for dual-polarization capable weather radars. The auto-covariance function of radar signal can be expressed as a sum of auto-covariance functions of the clutter, precipitation and noise that follow Gaussian forms. The filter matrix is designed such as when it is applied to the time

Cuong M. Nguyen; V. Chandrasekar; Dmitri N. Moisseev

2008-01-01

79

Systematic Variation of Observed Radar Reflectivity-Rainfall Rate Relations in the Tropics  

Microsoft Academic Search

The Tropical Rainfall Measuring Mission Global Validation Program provides a unique opportunity to compare radar datasets from different sites, because they are analyzed in a relatively uniform procedure. Monthly observed radar reflectivity-rainfall rate (Ze-R) relations for four different sites that are surrounded by tipping bucket gauge networks (Melbourne, Florida; Houston, Texas; Darwin, Australia; and Kwajalein Atoll, Republic of Marshall Islands)

Eyal Amitai

2000-01-01

80

Bias correction of satellite rainfall estimation using a radar-gauge product  

Microsoft Academic Search

Satellite rainfall estimates can be used in operational hydrologic prediction, but are prone to systematic errors. The goal of this study is to seamlessly blend a radar-gauge product with a corrected satellite product that fills gaps in radar coverage. To blend different rainfall products, they should have similar bias features. The paper presents a pixel by pixel method, which aims

K. Tesfagiorgis; S. E. Mahani; R. Khanbilvardi

2010-01-01

81

Radar rainfall estimation for flash flood forecasting in small urban watersheds  

Microsoft Academic Search

Radar rainfall estimation for flash flood forecasting in small, urban catchments is examined through analyses of radar, rain gage and discharge observations from the 14.3 km2 Dead Run drainage basin in Baltimore County, Maryland. The flash flood forecasting problem pushes the envelope of rainfall estimation to time and space scales that are commensurate with the scales at which the fundamental

James A. Smith; Mary Lynn Baeck; Katherine L. Meierdiercks; Andrew J. Miller; Witold F. Krajewski

2007-01-01

82

Radar rainfall estimation for flash flood forecasting in small urban watersheds  

Microsoft Academic Search

Radar rainfall estimation for flash flood forecasting in small, urban catchments is examined through analyses of radar, rain gage and discharge observations from the 14.3km2 Dead Run drainage basin in Baltimore County, Maryland. The flash flood forecasting problem pushes the envelope of rainfall estimation to time and space scales that are commensurate with the scales at which the fundamental governing

James A. Smith; Mary Lynn Baeck; Katherine L. Meierdiercks; Andrew J. Miller; Witold F. Krajewski

2007-01-01

83

Networked weather radar system using coherent on receive technology  

NASA Astrophysics Data System (ADS)

The Engineering Research Center for Collaborative Adapting Sensing of the Atmosphere (CASA) was established to improve the coverage of the lowest portion of the atmosphere through coordinated scanning of low-power, short-range, networked radars (referred to as Distributed Collaborative Adaptive Sensing (DCAS)). The first DCAS technology demonstration test-bed has been deployed in south-west Oklahoma in early 2006: a network of four, low-power, short-range, dual polarization, Doppler radar units, referred to as IPI (after CASA's Integrated Project 1). This dissertation is devoted to documenting the IP1 system. Special emphasis is placed on the aspects that enable coordinated radar operation and on other features that provide substantial improvements over existing approaches. In particular, the IP1 radar network can sample the atmosphere with high spatio-temporal resolution and at low altitudes. The dual polarization capabilities and simultaneous multiple radar observations of weather phenomena enable the retrieval of enhanced data products including attenuation corrected reflectivity, dual polarization parameters, and vector wind fields. In addition, the modular radar control, data processing, and communications software architecture allows variations in the network topology, control, and weather information extraction, making the extension of the network easy through the addition of potentially heterogeneous radar nodes.

Junyent, Francesc

84

Adjusting weather radar data to rain gauge measurements with data-driven models  

NASA Astrophysics Data System (ADS)

Weather radar networks provide data with good spatial coverage and temporal resolution. Hence they are able to describe the variability of precipitation. Typical radar stations determine the rain rate for every square kilometre and make a full volume scan within about 5 minutes. A weakness however, is their often poor metering precision limiting the applicability of the radar for hydrological purposes. In contrast to rain gauges, which measure precipitation directly on the ground, the radar determines the reflectivity aloft and remote. Due to this principle, several sources of possible errors occur. Therefore improving the radar estimates of rainfall is still a vital topic in radar meteorology and hydrology. This paper presents data-driven approaches to improve radar estimates of rainfall by mapping radar reflectivity measurements Z to rain gauge data R. The analysis encompasses several input configurations and data-driven models. Reflectivity measurements at a constant altitude and the vertical profiles of reflectivity above a rain gauge are used as input parameters. The applied models are Artificial Neural Network (ANN), Model Tree (MT), and IBk a k-nearest-neighbour classifier. The relationship found between the data of a rain gauge and the reflectivity measurements is subsequently applied to another site with comparable terrain. Based on this independent dataset the performance of the data-driven models in the various input configurations is evaluated. For this study, rain gauge and radar data from the province of Styria, Austria, were available. The data sets extend over a two-year period (2001 and 2002). The available rain gauges use the tipping bucket principle with a resolution of 0.1 mm. Reflectivity measurements are obtained from the Doppler weather radar station on Mt. Zirbitzkogel (by courtesy of AustroControl GmbH). The designated radar is a high-resolution C-band weather-radar situated at an altitude of 2372 m above mean sea level. The data-driven models exhibit different performances on the various input configurations. Also data transformations were applied. The logarithm recommends itself for this transformation because the original Z-R-relationship is a power function, and the logarithm linearises this non-linear relationship. The MT which is a piecewise linear model performs best on logarithmised data. The IBk works well when transforming the reflectivity data in rain rate first. Overall the ANN exhibits the best performance showing a 10 % improvement in correlation and RMSE compared to the standard Z-R-relationship. When applying the vertical profile of reflectivity as input parameter, the correlation exhibits a more than 30 % improvement. The results indicate that the vertical profile of reflectivity provided by weather radars yields not only information on the type of precipitation, whether it is stratiform or convective. In data-driven models the vertical profile of reflectivity can help to get better estimates of rain rates on the ground, even in mountainous terrain without low-altitude radar measurements.

Teschl, Reinhard; Randeu, Walter; Teschl, Franz

2010-05-01

85

ASSIMILATION OF DOPPLER RADAR DATA INTO NUMERICAL WEATHER MODELS  

SciTech Connect

During the year 2008, the United States National Weather Service (NWS) completed an eight fold increase in sampling capability for weather radars to 250 m resolution. This increase is expected to improve warning lead times by detecting small scale features sooner with increased reliability; however, current NWS operational model domains utilize grid spacing an order of magnitude larger than the radar data resolution, and therefore the added resolution of radar data is not fully exploited. The assimilation of radar reflectivity and velocity data into high resolution numerical weather model forecasts where grid spacing is comparable to the radar data resolution was investigated under a Laboratory Directed Research and Development (LDRD) 'quick hit' grant to determine the impact of improved data resolution on model predictions with specific initial proof of concept application to daily Savannah River Site operations and emergency response. Development of software to process NWS radar reflectivity and radial velocity data was undertaken for assimilation of observations into numerical models. Data values within the radar data volume undergo automated quality control (QC) analysis routines developed in support of this project to eliminate empty/missing data points, decrease anomalous propagation values, and determine error thresholds by utilizing the calculated variances among data values. The Weather Research and Forecasting model (WRF) three dimensional variational data assimilation package (WRF-3DVAR) was used to incorporate the QC'ed radar data into input and boundary conditions. The lack of observational data in the vicinity of SRS available to NWS operational models signifies an important data void where radar observations can provide significant input. These observations greatly enhance the knowledge of storm structures and the environmental conditions which influence their development. As the increase in computational power and availability has made higher resolution real-time model simulations possible, the need to obtain observations to both initialize numerical models and verify their output has become increasingly important. The assimilation of high resolution radar observations therefore provides a vital component in the development and utility of numerical model forecasts for both weather forecasting and contaminant transport, including future opportunities to improve wet deposition computations explicitly.

Chiswell, S.; Buckley, R.

2009-01-15

86

Estimating subcatchment runoff coefficients using weather radar and a downstream runoff sensor.  

PubMed

This paper presents a method for estimating runoff coefficients of urban drainage subcatchments based on a combination of high resolution weather radar data and flow measurements from a downstream runoff sensor. By utilising the spatial variability of the precipitation it is possible to estimate the runoff coefficients of the separate subcatchments. The method is demonstrated through a case study of an urban drainage catchment (678 ha) located in the city of Aarhus, Denmark. The study has proven that it is possible to use corresponding measurements of the relative rainfall distribution over the catchment and downstream runoff measurements to identify the runoff coefficients at subcatchment level. PMID:24056426

Ahm, Malte; Thorndahl, Søren; Rasmussen, Michael R; Bassø, Lene

2013-01-01

87

Initialization Analysis of IIR Ground Clutter Filter in Doppler Weather Radar  

Microsoft Academic Search

This paper analyzes the initialization of IIR ground clutter filter (GCF) in Doppler weather radar. The transients of IIR GCF degrade the theoretical frequency response and different initialization technique produces different suppression characteristic. The initialization performance is tested both with a simulated weather radar signal and an actual weather radar signal. We explore the relation between clutter suppression ratio (the

Yuchun Gao; Yan Liu; He Jianxin

2007-01-01

88

Doppler weather radar as a meteorite recovery tool  

NASA Astrophysics Data System (ADS)

We report the use of Doppler weather radar as a tool for locating meteorites, both at the time of a fall and from archived radar data. This asset is especially useful for meteorite recovery as it can provide information on the whereabouts of falling meteorites in "dark flight" portion of their descent where information on their flight paths cannot be discerned from more traditional meteorite location techniques such as eyewitness accounts. Weather radar data can provide information from detection in three distinct regimes: (A) direct detection of the rapidly moving, optically bright fireball by distant radars, (B) detection of falling debris to include hand-sample sized rocks, and (C) detection of dust produced by detonation events that can occur tens of minutes and many kilometers laterally removed from the actual fireball locality. We present examples of each, as well as comparisons against man-made debris from a re-entering Soyuz rocket and the Stardust Sample Return Capsule. The use of Doppler weather radar as a supplement to traditional meteorite recovery methods holds the promise of improving both the speed and total number of meteorite recoveries, thereby increasing the number of freshly fallen meteorites for scientific study.

Fries, Marc; Fries, Jeffrey

2010-09-01

89

TDWR (Terminal Doppler Weather Radar) scan strategy requirements  

Microsoft Academic Search

The requirements for the scan strategy to be employed in the Terminal Doppler Weather Radar (TDWR) are described. The report is divided into three main sections: rationale, example scan strategy and requirements. The rationale for the TDWR scan strategy is presented in terms of: (1) detection of meteorological phenomena, and (2) minimization of range and velocity folding effects. Next, an

S. D. Campbell; M. W. Merritt

1988-01-01

90

Enhancements to the terminal Doppler weather radar gust front algorithm  

Microsoft Academic Search

During the 1988 Operational Test and Evaluation of the FAA's Terminal Doppler Weather Radar (TDWR) system, a real-time test of the gust front algorithm capabilities in a High Plains environment (Denver, CO) was accomplished. Further evaluation of the algorithm's detection capability in the Great Planes (Kansas City, KA) was conducted in 1989. Deficiencies in several techniques used by the TDWR

Laurie G. Hermes; Kevin W. Thomas; Gregory J. Stumpf; Michael D. Eilts; Edward Brandes; Dusan Zrnic; Richard Doviak; Arthur Witt

1990-01-01

91

Influence of errors in radar rainfall estimates on hydrological modeling prediction uncertainty  

NASA Astrophysics Data System (ADS)

This study aims to assess the impact of a class of radar rainfall errors on prediction uncertainty of a conceptual water balance model. Uncertainty assessment is carried out by means of the Generalized Likelihood Uncertainty Estimation procedure (GLUE). The effects of model input and structural error are separated, and the potential for compensating errors between them is investigated. It is shown that the radar rainfall bias term operates in a multiplicative sense on the model structural uncertainty, by either magnifying or reducing it according to the sign of the bias. The results show also that adjustment of radar rainfall, aimed to remove local biases and to reduce random errors, allows ensuring that a larger percentage of the observed flows are enclosed by the uncertainty bounds, with respect to nonadjusted radar input. However, this is obtained at the price of increasing the wideness of the uncertainty bounds. This effect is emphasized with increasing the radar beam elevation. As a second step, the issue of the impact of radar rainfall estimation error on model parameter distribution and parameter transferability across sites under the radar umbrella is examined. Radar data at different radar beam elevations are used to simulate radar estimation errors at different distances from the radar site and to analyze the impact of these errors on prediction uncertainty. The results show that distortion of parameter distribution due to radar error may be considerable and that adjustment of radar rainfall estimates improves the regionalization potential of radar-based precipitation estimates (at least for ranges less than 70 km).

Borga, Marco; Degli Esposti, Silvia; Norbiato, Daniele

2006-08-01

92

Influence of rainfall-induced wetting on the stability of slopes in weathered soils  

Microsoft Academic Search

Shallow failures of slopes in weathered soil are caused by infiltration due to prolonged rainfall. These failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in matric suction induced by the water infiltration. This paper reports trends of rainfall-induced wetting band depth in two types of weathered soils that are commonly found in Korea.

Jaehong Kim; Sangseom Jeong; Jitendra Sharma

2004-01-01

93

Hydroclimatologic Analyses of Extreme Rainfall and Flooding in Atlanta, Georgia Using Long-Term Radar-Rainfall Datasets  

NASA Astrophysics Data System (ADS)

A 10-year radar rainfall dataset is being developed for the Atlanta, Georgia metropolitan area using the Hydro-NEXRAD algorithms. Radar rainfall fields are constructed at 15 minute time resolution and 1 km spatial resolution; observations from a dense network of rain gages are used for multiplicative bias correction. The high-resolution dataset will permit the investigation of urban effects on the initiation and evolution of heavy rainfall events. In addition, the climatology of extreme rainfall-runoff relationships will be examined with the aim of improving the understanding of the water balance and flood response of urban catchments during extreme rainfall events. Analyses relating the temporal and spatial distribution of rainfall to basin scale and land-use/land-cover characteristics will assist in developing urban flood frequency relationships. Events of particular interest are the floods of September 20-21, 2009 and May 3-4, 2010, which caused heavy damage and fatalities in portions of the southeastern US including Atlanta. Similar bias-corrected radar datasets in development for the Baltimore, Charlotte, and Milwaukee metropolitan areas will allow for the comparison of climatology of extreme rainfall and urban flooding in different regions of the United States and under different climate regimes.

Wright, D. B.; Smith, J. A.; Baeck, M. L.; Villarini, G.

2010-12-01

94

Comparative Analysis of Radar and Gauge Rainfall Data By The A,b-diagrams  

NASA Astrophysics Data System (ADS)

For hydrology application it's important that radar rainfall measurements correspond to gauge data more precisely as possible. In fact only ground measurements are sole criterion of radar rainfall measurements quality. But this criterion isn't absolute: firstly, gauges as well as radars have some own errors, secondly accurate correspondence of radar and gauges data we can't wait because of principal inequality of instrument sensitive volumes. For correct calibration radar main part of its rainfall measurement inaccuracy determines by natural DSD variations, under condition of exact measure- ment of Z. Obviously that if we know "radar zone-average" DSD characteristics (and its bind bulk parameters, as A and b coefficients in Z-R relations) we can have essen- tial increased accuracy of radar rainfall measurements. This information is interesting for the best understanding of natural parameter variation limits. But we haven't clear understanding about the coefficients variation magnitude for different types of precip- itation as yet. In present report we investigate the behavior of statistical consistency criteria of radar and gauge rainfall data, such as regression coefficient, RMS differ- ence, correlation coefficient, in A,b-parameters space on purpose to find parameter set of optimal radar-to-gauge data accordance. Such analysis has allowed us to reveal interesting features of optimal parameter value distribution in different precipitation conditions. Proposed approach for data analysis is applicable to identification aver- aged parameters for different length rainfall accumulation period: from few minutes to day, decade, season etc. Our conclusions are corroborated by the examples from our long time period radar observations of summer and winter precipitations by dual- bands (S and X) radar in Moscow.

Pavlyukov, Yu. B.; Melnichuk, Yu. V.

95

Design of a Digital Simulation of the Polar Planimeter for Calculating Areas of Echoes from Radar Weather Observations.  

National Technical Information Service (NTIS)

The effort discussed in the report was to fulfill a requirement for expediently analyzing data on radar weather prediction techniques. Data is recorded at various radar stations, which make hourly weather observations on the local weather activity within ...

R. G. Kelley

1968-01-01

96

Rainfall estimation by rain gauge-radar combination: A concurrent multiplicative-additive approach  

NASA Astrophysics Data System (ADS)

A procedure (concurrent multiplicative-additive objective analysis scheme [CMA-OAS]) is proposed for operational rainfall estimation using rain gauges and radar data. On the basis of a concurrent multiplicative-additive (CMA) decomposition of the spatially nonuniform radar bias, within-storm variability of rainfall and fractional coverage of rainfall are taken into account. Thus both spatially nonuniform radar bias, given that rainfall is detected, and bias in radar detection of rainfall are handled. The interpolation procedure of CMA-OAS is built on Barnes' objective analysis scheme (OAS), whose purpose is to estimate a filtered spatial field of the variable of interest through a successive correction of residuals resulting from a Gaussian kernel smoother applied on spatial samples. The CMA-OAS, first, poses an optimization problem at each gauge-radar support point to obtain both a local multiplicative-additive radar bias decomposition and a regionalization parameter. Second, local biases and regionalization parameters are integrated into an OAS to estimate the multisensor rainfall at the ground level. The procedure is suited to relatively sparse rain gauge networks. To show the procedure, six storms are analyzed at hourly steps over 10,663 km2. Results generally indicated an improved quality with respect to other methods evaluated: a standard mean-field bias adjustment, a spatially variable adjustment with multiplicative factors, and ordinary cokriging.

GarcíA-Pintado, Javier; Barberá, Gonzalo G.; Erena, Manuel; Castillo, Victor M.

2009-01-01

97

TDWR (Terminal Doppler Weather Radar) PRF (Pulse Repetition Frequency) selection criteria  

Microsoft Academic Search

The Terminal Doppler Weather Radar (TDWR) system shall provide high quality Doppler radar data on weather phenomena near high traffic airports. These data shall be used in real time by automated TDWR algorithms to detect weather situations which may be hazardous to the safe operation of aircraft within the vicinity of the airport. One of the major factors which could

S. C. Crocker

1988-01-01

98

ERRORS IN SURFACE RAINFALL RATES RETRIEVED FROM RADAR DUE TO WIND DRIFT  

Microsoft Academic Search

A major assumption when using radar retrieved precipitation observations in hydrological applications is that the precipitation observed aloft impacts the surface directly below the volume sampled by the radar. However, it is well known that rain may be advected laterally considerable distances, implying that rainfall entered into distributed hydrological models will be inaccurate no matter how accurately the rain is

Steven A. Lack; Neil I. Fox

2004-01-01

99

Estimation of rainfall field by combining radar data and raingauge observations: the modified conditional merging technique  

NASA Astrophysics Data System (ADS)

The estimation of rainfall fields, especially its spatial distribution and position is a crucial task both for rainfall nowcasting and for modeling catchment response to rainfall. Some studies of literature about multisensor datafusion prove that combining data from raingauges and radar represents the best way to obtain an enhanced ad more reliable estimation of QPE and of the associated river discharge. Sinclair and Peagram (2004) have proposed the Conditional Merging (CM) technique, a merging algorithm which extract the information content from the observed data and use it within an interpolation method to obtain the rainfall maps. The raingauges provide a punctual measure of the ground-observed rainfall while the remote sensors (radar network or satellite constellation) supply rainfall estimation maps which give an idea of the correlation and structure of covariance of the observed field. In this work is presented an algorithm called Modified Conditional Merging that is based on CM and which is used for real-time estimation of the optimal rainfall maps. The area of interest is Italy, where are both available a dense network of raingauge measurements (about 2000 stations) and a QPE estimated by the Italian Radar composite. The main innovation respect to classical CM is to estimate the structure of covariance and the length of spatial correlation ?, for every raingauge, directly from the cumulated radar rainfall fields. An application to several test cases together with the evaluation of algorithm performances are presented and discussed.

Pignone, F.; Rebora, N.; Silvestro, F.

2012-04-01

100

10 cm Dual Frequency Doppler Weather Radar. Part II. A Quality Assurance/Fault Location Network.  

National Technical Information Service (NTIS)

A functional description of an automatic radar system performance monitoring network is presented. A network of microprocessor controlled monitoring units were interfaced to various sensors at key areas in a Doppler weather radar in order to collect syste...

K. J. Banis

1982-01-01

101

Processing of Indian Doppler Weather Radar data for mesoscale applications  

NASA Astrophysics Data System (ADS)

This paper demonstrates the usefulness of Indian Doppler Weather Radar (DWR) data for nowcasting applications, and assimilation into a mesoscale Numerical Weather Prediction (NWP) model. Warning Decision Support System Integrated Information (WDSS-II) developed by National Severe Storm Laboratory (NSSL) and Advanced Regional Prediction System (ARPS) developed at the Centre for Analysis and Prediction, University of Oklahoma are used for this purpose. The study reveals that the WDSS-II software is capable of detecting and removing anomalous propagation echoes from the Indian DWR data. The software can be used to track storm cells and mesocyclones through successive scans. Radar reflectivity mosaics are created for a land-falling tropical cyclone—Khaimuk of 14 November 2008 over the Bay of Bengal using observations from three DWR stations, namely, Visakhapatnam, Machilipatnam and Chennai. Assimilation of the quality-controlled radar data (DWR, Chennai) of the WDSS-II software in a very high-resolution NWP model (ARPS) has a positive impact for improving mesoscale prediction. This has been demonstrated for a land-falling tropical cyclone Nisha of 27 November 2008 of Tamil Nadu coast. This paper also discusses the optimum scan strategy and networking considerations. This work illustrates an important step of transforming research to operation.

Roy Bhowmik, S. K.; Sen Roy, Soma; Srivastava, Kuldeep; Mukhopadhay, B.; Thampi, S. B.; Reddy, Y. K.; Singh, Hari; Venkateswarlu, S.; Adhikary, Sourav

2011-03-01

102

On precipitation measurements collected by a weather radar and a rain gauge network  

NASA Astrophysics Data System (ADS)

Many phenomena (such as attenuation and range degradation) can influence the accuracy of rainfall radar estimates. They introduce errors that increase as the distance from radar increases, thereby decreasing the reliability of radar estimates for applications that require quantitative precipitation estimation. The present paper evaluates radar error as a function of the range, in order to correct the rainfall radar estimates. The radar is calibrated utilizing data from the rain gauges. Then, the G/R ratio between the yearly rainfall amount measured in each rain gauge position during 2008 and the corresponding radar rainfall amount is calculated against the slant range. The trend of the G/R ratio shows two behaviours: a concave part due to the melting layer effect close to the radar location and an almost linear, increasing trend at greater distances. A best fitting line is used to find an adjustment factor, which estimates the radar error at a given range. The effectiveness of the methodology is verified by comparing pairs of rainfall time series that are observed simultaneously by collocated rain gauges and radar. Furthermore, the variability of the adjustment factor is investigated at the scale of event, both for convective and stratiform events. The main result is that there is not a univocal range error pattern, as it also depends on the characteristics of the considered event. On the other hand, the adjustment factor tends to stabilize itself for time aggregations of the order of one year or greater.

Sebastianelli, S.; Russo, F.; Napolitano, F.; Baldini, L.

2013-03-01

103

Terminal Doppler weather radar operational test and evaluation, Orlando 1990  

NASA Astrophysics Data System (ADS)

Lincoln Laboratory conducted an evaluation of the Federal Aviation Administration (FAA) Terminal Doppler Weather Radar (TDWR) system in Orlando, Florida during the summer of 1990. In previous years, evaluations have been conducted at airports in Kansas City, MO (1989) and Denver, CO (1988). Since the testing at the Kansas City International Airport, the radar was modified to operate in C-band, which is the intended frequency band for the production TDWR systems. The objectives of the 1990 evaluation period were to evaluate TDWR system performance in detecting low-altitude wind shear, specifically microbursts and gust fronts, at the Orlando International Airport and in the surrounding area; to refine the system's wind shear detection capabilities; and to evaluate elements of the system developed by the contractor, which were new for the C-band system and therefore not available for evaluation in previous years. Some performance comparisons are made among results from the vastly different weather environments of Denver, Kansas City, and Orlando. Statistics are presented and discussed for the performance of the system in detecting and predicting microbursts and gust fronts. A significant use of the prediction capability is its potential use for air traffic control (ATC) personnel to plan airport operations when hazardous weather is predicted. Issues such as low velocity ground clutter (from tree leaves, road traffic, and dense urban areas) that affect prediction performance are discussed along with possible software modification to account for them.

Bernella, David M.

1991-04-01

104

Weather radar signatures derived from simulated volcanic plumes  

NASA Astrophysics Data System (ADS)

Explosive volcanic eruptions form ash clouds that pose a severe threat to aviation safety and to infrastructure on the ground. For the prediction of the plume track and ash fall it is necessary to know the characteristics of the initial plume in terms of its size, height and its particle concentrations and size distribution. The differentiation between ash particles, pure hydrometeors like ice crystals and aggregates is important because the ash signal can be obscured by the presence of water and ice in the plume. Since direct observations of volcanic plumes are nearly impossible, remote sensing techniques, like microwave weather radar, offer a unique tool to gain valuable information about the plume and its particles. In order to adequately test the retrieval algorithm for deriving the physical plume properties from radar signals, independent measurements of plume characteristics are required. Numerical modeling of the plume provides a unique opportunity whereby all physical parameters are known to very high temporal and spatial resolution without observational errors. For this purpose we applied the plume model ATHAM (Active Tracer High Resolution Atmospheric Model) to the eruption of the Etna volcano in 2002. Radar reflectivities were calculated for the simulated volcanic plume under different assumptions and scenarios and compared to the corresponding available C-band radar observations.

Herzog, Michael; Mather, Luke; Giuliani, Graziano; Marzano, Frank

2010-05-01

105

Winter precipitation fields in the Southeastern Mediterranean area as seen by the Ku-band spaceborne weather radar and two C-band ground-based radars  

NASA Astrophysics Data System (ADS)

The spaceborne weather radar onboard the Tropical Rainfall Measuring Mission (TRMM) satellite can be used to adjust Ground-based Radar (GR) echoes, as a function of the range from the GR site. The adjustment is based on the average linear radar reflectivity in circular rings around the GR site, for both the GR and attenuation-corrected NearSurfZ TRMM Precipitation Radar (TPR) images. In previous studies, it was found that in winter, for the lowest elevation of the Cyprus C-band radar, the GR/TPR equivalent rain rate ratio was decreasing, on average, of approximately 8 dB per decade. In this paper, the same analysis has been applied to another C-band radar in the southeastern Mediterranean area. For the lowest elevation of the "Shacham" radar in Israel, the GR/TPR equivalent rain rate ratio is found to decrease of approximately 6 dB per decade. The average departure at the "reference", intermediate range is related to the calibration of the GR. The negative slope of the range dependence is considered to be mainly caused by an overshooting problem (increasing sampling volume of the GR with range combined with non-homogeneous beam filling and, on average, a decreasing vertical profile of radar reflectivity). To check this hypothesis, we have compared the same NearSurfZ TPR images versus GR data acquired using the second elevation. We expected these data to be affected more by overshooting, especially at distant ranges: the negative slope of the range dependence was in fact found to be more evident than in the case of the lowest GR elevation for both the Cypriot and Israeli radar.

Gabella, M.; Morin, E.; Notarpietro, R.; Michaelides, S.

2013-01-01

106

Scale Dependence of Radar-Rainfall Uncertainty Based on the New Super-Resolution Data of NEXRAD  

NASA Astrophysics Data System (ADS)

Quantitative estimation of radar rainfall is necessary for various hydrologic applications such as flood forecasting models, hydrosystem operation and control, and design of hydraulic structures. Different applications may require different resolution in space and time of the rainfall input. Thus, quantifying rainfall uncertainties with respect to scale is essential to provide better understanding in using higher-resolution precipitation data. In summer of 2008 NEXRAD's WSR-88D S-band weather radars commenced providing enhanced base data. The new data, called super-resolution, have higher resolution than the legacy-resolution of a 1 km in range by 1 degree in azimuth of Level II volume scans. The super-resolution data are produced for "split cuts" that depend on Volume Coverage Pattern and the grid spacing of reflectivity data are reduced to 0.5° in azimuth and to 250 m in range. Although super-resolution data may capture small scale features of precipitation with more reliability, NEXRAD Precipitation Processing System still operates based on recombined (legacy-resolution) data. Therefore, the authors tested the potential provided by the new data using the off-line precipitation estimation algorithms of the Hydro-NEXRAD system. The algorithms allow obtaining rain maps with the resolution about 0.5 km. Since super-resolution data have been implemented only in recent months, the authors evaluate the super-resolution precipitation estimates with recombined legacy products and rain gauge data for several rain events that led to extreme flooding in the Iowa River and Cedar River basins in June of 2008. They discuss the spatial scale dependence of uncertainties for gauge representativeness and radar rainfall estimation based on spatial averaging schemes.

Krajewski, W. F.; Seo, B. C.

2009-04-01

107

TDWR (Terminal Doppler Weather Radar) scan strategy requirements  

NASA Astrophysics Data System (ADS)

The requirements for the scan strategy to be employed in the Terminal Doppler Weather Radar (TDWR) are described. The report is divided into three main sections: rationale, example scan strategy and requirements. The rationale for the TDWR scan strategy is presented in terms of: (1) detection of meteorological phenomena, and (2) minimization of range and velocity folding effects. Next, an example is provided based on an experimental scan strategy used in Denver during the summer of 1987. Finally, the requirements for the TDWR scan strategy are presented based on the preceeding discussion. Also, an appendix is included describing the proposed criteria for switching between scan modes.

Campbell, S. D.; Merritt, M. W.

1988-11-01

108

Cross-validation of spaceborne radar and ground polarimetric radar observations  

Microsoft Academic Search

There is great potential for spaceborne weather radar to make significant observations of the precipitating medium on global scales. The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall in the tropics from space using radar. The Precipitation Radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular

Steven Matthew Bolen

2002-01-01

109

The use of radar data assimilation to improve warm season heavy rainfall forecasts for use in hydrologic models  

NASA Astrophysics Data System (ADS)

Warm Season convective rainfall is one of the most poorly forecast parameters in numerical models, which is unfortunate since this rainfall often occurs with very high rates which can lead to flooding if the duration of the event is sufficiently long. Because quantitative precipitation forecasting (QPF) skill has traditionally been poor, these forecasts are not used in hydrologic modeling for stream flow. Instead, stream flow forecasts are made using estimates of precipitation that has fallen, reducing the amount of lead time for warnings from what could exist if forecasts were used. Thus a continued focus in the meteorological community has been on increasing the forecasting accuracy of warm season convective rainfall. Numerical weather forecasting has always suffered from the inability to accurately observe the state of the atmosphere; thus, model initial conditions cannot accurately portray the true state of the atmosphere. These initial observations (being inaccurate to a certain degree) result in growth of error in the model through time. This presentation will focus on the the impact of adjusted initial conditions in the Weather Research and Forecasting (WRF) model through the assimilation of radar data to increase the accuracy of the initialization. The WRF has been run with convection-allowing grid spacing over a domain covering roughly 800 x 800 km centered over Iowa. The model is being run for several heavy rain events that occurred over the Midwest. The QPF skill of the model over the first 12 forecast hours with radar data assimilation will be compared to the skill of the same model without radar data assimilation. The use of radar data assimilation in the Center for the Analysis and Prediction of Storms (CAPS) ensemble has been found to noticeably improve forecasts, especially over the first 6-12 hours. This project will focus on quantifying the impact of such assimilation on rainfall forecasts in Iowa, and on hydrologic forecasts that use the QPF. If skill is found on average to improve sufficiently, it may be possible to extend warning lead time by several hours through the use of this QPF.

Moser, Benjamin; Gallus, William; Mantilla, Ricardo; Krajewski, Witold

2013-04-01

110

Bird migration flight altitudes studied by a network of operational weather radars.  

PubMed

A fully automated method for the detection and quantification of bird migration was developed for operational C-band weather radar, measuring bird density, speed and direction as a function of altitude. These weather radar bird observations have been validated with data from a high-accuracy dedicated bird radar, which was stationed in the measurement volume of weather radar sites in The Netherlands, Belgium and France for a full migration season during autumn 2007 and spring 2008. We show that weather radar can extract near real-time bird density altitude profiles that closely correspond to the density profiles measured by dedicated bird radar. Doppler weather radar can thus be used as a reliable sensor for quantifying bird densities aloft in an operational setting, which--when extended to multiple radars--enables the mapping and continuous monitoring of bird migration flyways. By applying the automated method to a network of weather radars, we observed how mesoscale variability in weather conditions structured the timing and altitude profile of bird migration within single nights. Bird density altitude profiles were observed that consisted of multiple layers, which could be explained from the distinct wind conditions at different take-off sites. Consistently lower bird densities are recorded in The Netherlands compared with sites in France and eastern Belgium, which reveals some of the spatial extent of the dominant Scandinavian flyway over continental Europe. PMID:20519212

Dokter, Adriaan M; Liechti, Felix; Stark, Herbert; Delobbe, Laurent; Tabary, Pierre; Holleman, Iwan

2010-06-02

111

On the Use of Auxiliary Receive Channels for Clutter Mitigation With Phased Array Weather Radars  

Microsoft Academic Search

Phased array radars (PARs) are attractive in weather surveillance primarily because of their capability to electronically steer. When combined with the recently developed beam multiplexing (BMX) technique, these radars can obtain very rapid update scans that are useful in monitoring severe weather. A consequence is that the small number of contiguous samples of the time series obtained can be a

Khoi D. Le; Robert D. Palmer; Boon Leng Cheong; Tian-You Yu; Guifu Zhang; Sebastian M. Torres

2009-01-01

112

Offshore next generation weather radar (NEXRAD) test and evaluation master plan (TEMP)  

Microsoft Academic Search

This document provides the test philosophy and approach for the Offshore Next Generation Weather Radar (NEXRAD) Test and Evaluation Master Plan (TEMP). The NEXRAD differs from the typical Federal Aviation Administration (FAA) weather radar acquisition in that it is jointly funded by the Department of Defense (DOD), the Department of Commerce (DOC), and the Department of Transportation (DOT). These three

Radame Martinez; Robert Cranston; John Porcello

1995-01-01

113

A PRELIMINARY STUDY OF VERTICAL RADAR REFLECTIVITY PROFILES OVER THE ODRA BASIN  

Microsoft Academic Search

Accurate real-time rainfall measurements are quite important for hydrological modelling and forecasting. Weather radars can give a good estimate of precipitation when the data are properly processed. An important error source in the estimation of precipitation using weather radars is the variation of the Vertical Reflectivity Profile (VRP) of precipitation. In order to improve radar rainfall measurements is important to

Miguel Angel Rico-Ramirez; Ian David Cluckie; Teresa Zawislak; Wiwiana Szalinska

114

Technical Note: An open source library for processing weather radar data (wradlib)  

NASA Astrophysics Data System (ADS)

The potential of weather radar observations for hydrological and meteorological research and applications is undisputed, particularly with increasing world-wide radar coverage. However, several barriers impede the use of weather radar data. These barriers are of both scientific and technical nature. The former refers to inherent measurement errors and artefacts, the latter to aspects such as reading specific data formats, geo-referencing, visualisation. The radar processing library wradlib is intended to lower these barriers by providing a free and open source tool for the most important steps in processing weather radar data for hydro-meteorological and hydrological applications. Moreover, the community-based development approach of wradlib allows scientists to share their knowledge about efficient processing algorithms and to make this knowledge available to the weather radar community in a transparent, structured and well-documented way.

Heistermann, M.; Jacobi, S.; Pfaff, T.

2013-02-01

115

Statistical evaluation of a radar rainfall system for sewer system management  

Microsoft Academic Search

Urban areas are faced with mounting demands for managing waste and stormwater for a cleaner environment. Rainfall information is a critical component in efficient management of urban drainage systems. A major water quality impact affecting receiving waterbodies is the discharge of untreated waste and stormwater during precipitation, termed wet weather flow. Elimination or reduction of wet weather flow in metropolitan

B. E. Vieux; J. E. Vieux

2005-01-01

116

Statistical analysis and modelling of weather radar beam propagation conditions in the Po Valley (Italy)  

NASA Astrophysics Data System (ADS)

Ground clutter caused by anomalous propagation (anaprop) can affect seriously radar rain rate estimates, particularly in fully automatic radar processing systems, and, if not filtered, can produce frequent false alarms. A statistical study of anomalous propagation detected from two operational C-band radars in the northern Italian region of Emilia Romagna is discussed, paying particular attention to its diurnal and seasonal variability. The analysis shows a high incidence of anaprop in summer, mainly in the morning and evening, due to the humid and hot summer climate of the Po Valley, particularly in the coastal zone. Thereafter, a comparison between different techniques and datasets to retrieve the vertical profile of the refractive index gradient in the boundary layer is also presented. In particular, their capability to detect anomalous propagation conditions is compared. Furthermore, beam path trajectories are simulated using a multilayer ray-tracing model and the influence of the propagation conditions on the beam trajectory and shape is examined. High resolution radiosounding data are identified as the best available dataset to reproduce accurately the local propagation conditions, while lower resolution standard TEMP data suffers from interpolation degradation and Numerical Weather Prediction model data (Lokal Model) are able to retrieve a tendency to superrefraction but not to detect ducting conditions. Observing the ray tracing of the centre, lower and upper limits of the radar antenna 3-dB half-power main beam lobe it is concluded that ducting layers produce a change in the measured volume and in the power distribution that can lead to an additional error in the reflectivity estimate and, subsequently, in the estimated rainfall rate.

Fornasiero, A.; Alberoni, P. P.; Bech, J.

2006-05-01

117

Development of precipitation radar onboard the Tropical Rainfall Measuring Mission (TRMM) satellite  

Microsoft Academic Search

The precipitation radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite is the first spaceborne radar to measure precipitation from space. The PR, operating at 13.8 GHz, is a 128-element active phased array that allows a fast and sophisticated cross-track scanning over a swath width of 215 km with a cross-range spatial resolution of about 4.3 km. The PR

Toshiaki Kozu; Toneo Kawanishi; Hiroshi Kuroiwa; Masahiro Kojima; Koki Oikawa; Hiroshi Kumagai; K. Okamoto; M. Okumura; H. Nakatsuka; K. Nishikawa

2001-01-01

118

Effect of radar rainfall time resolution on the predictive capability of a distributed hydrologic model  

NASA Astrophysics Data System (ADS)

The performance of a hydrologic model depends on the rainfall input data, both spatially and temporally. As the spatial distribution of rainfall exerts a great influence on both runoff volumes and peak flows, the use of a distributed hydrologic model can improve the results in the case of convective rainfall in a basin where the storm area is smaller than the basin area. The aim of this study was to perform a sensitivity analysis of the rainfall time resolution on the results of a distributed hydrologic model in a flash-flood prone basin. Within such a catchment, floods are produced by heavy rainfall events with a large convective component. A second objective of the current paper is the proposal of a methodology that improves the radar rainfall estimation at a higher spatial and temporal resolution. Composite radar data from a network of three C-band radars with 6-min temporal and 2 × 2 km2 spatial resolution were used to feed the RIBS distributed hydrological model. A modification of the Window Probability Matching Method (gauge-adjustment method) was applied to four cases of heavy rainfall to improve the observed rainfall sub-estimation by computing new Z/R relationships for both convective and stratiform reflectivities. An advection correction technique based on the cross-correlation between two consecutive images was introduced to obtain several time resolutions from 1 min to 30 min. The RIBS hydrologic model was calibrated using a probabilistic approach based on a multiobjective methodology for each time resolution. A sensitivity analysis of rainfall time resolution was conducted to find the resolution that best represents the hydrological basin behaviour.

Atencia, A.; Mediero, L.; Llasat, M. C.; Garrote, L.

2011-12-01

119

Enhancements to the terminal Doppler weather radar gust front algorithm  

NASA Astrophysics Data System (ADS)

During the 1988 Operational Test and Evaluation of the FAA's Terminal Doppler Weather Radar (TDWR) system, a real-time test of the gust front algorithm capabilities in a High Plains environment (Denver, CO) was accomplished. Further evaluation of the algorithm's detection capability in the Great Planes (Kansas City, KA) was conducted in 1989. Deficiencies in several techniques used by the TDWR gust front algorithm were noted. As a result, modifications such as feature error checking and feature checking prior to polynomial fitting were included in the algorithm. Improvements to the techniques used to vertically associate features, determine gust front orientations, and to produce gust front representations and forecasts were also implemented. False algorithm detections, specifically those caused by the detection of radial convergence associated with low-level jet phenomenon, are discussed.

Hermes, Laurie G.; Thomas, Kevin W.; Stumpf, Gregory J.; Eilts, Michael D.; Brandes, Edward; Zrnic, Dusan; Doviak, Richard; Witt, Arthur

1990-12-01

120

Rainfall Generator for the Rhine Basin. Nearest-Neighbour Resampling of Daily Circulation Indices and Conditional Generation of Weather Variables.  

National Technical Information Service (NTIS)

The KNMI rainfall generator is a non-parametric stochastic weather generator based on nearest neighbor resampling of historical data. The weather generator produces daily values of precipitation and temperature. The latter is needed for the calculation of...

J. J. Beersma T. A. Buishand

1999-01-01

121

DSD IDENTIFICATION FOLLOWING A PRE-CLASSIFICATION OF RAINFALL TYPE FROM RADAR ANALYSIS  

Microsoft Academic Search

The analysis of the rain drop size distribution (DSD) is a key point in the understanding of the physical processes that govern the rainfall properties widely used in meteorology, hydrometeorology, and specially in radar meteorology studies (Joss and Zawadzki 1997). In the methodology for DSD analysis proposed by Marshall and Palmer in 1948, an average DSD is determined for a

Daniel Sempere-Torres; Rafael Sánchez-Diezma; Isztar Zawadzki; J. Dominique Creutin

122

Observations of Heavy Rainfall in a Post Wildland Fire Area Using X-Band Polarimetric Radar  

NASA Astrophysics Data System (ADS)

Polarimetric X-band radar systems have been used increasingly over the last decade for rainfall measurements. Since X-band radar systems are generally less costly, more mobile, and have narrower beam widths (for same antenna sizes) than those operating at lower frequencies (e.g., C and S-bands), they can be used for the "gap-filling" purposes for the areas when high resolution rainfall measurements are needed and existing operational radars systems lack adequate coverage and/or resolution for accurate quantitative precipitation estimation (QPE). The main drawback of X-band systems is attenuation of radar signals, which is significantly stronger compared to frequencies used by "traditional" precipitation radars operating at lower frequencies. The use of different correction schemes based on polarimetric data can, to a certain degree, overcome this drawback when attenuation does not cause total signal extinction. This presentation will focus on examining the use of high-resolution data from the NOAA Earth System Research Laboratory (ESRL) mobile X-band dual polarimetric radar for the purpose of estimating precipitation in a post-wildland fire area. The NOAA radar was deployed in the summer of 2011 to examine the impact of gap-fill radar on QPE and the resulting hydrologic response during heavy rain events in the Colorado Front Range in collaboration with colleagues from the National Center for Atmospheric Research (NCAR), Colorado State University (CSU), and the U.S. Geological Survey (USGS). A network of rain gauges installed by NCAR, the Denver Urban Drainage Flood Control District (UDFCD), and the USGS are used to compare with the radar estimates. Supplemental data from NEXRAD and the CSU-CHILL dual polarimetric radar are also used to compare with the NOAA X-band and rain gauges. It will be shown that rainfall rates and accumulations estimated from specific differential phase measurements (KDP) at X-band are in good agreement with the measurements from the gauge network during heavy rain and rain/hail mixture events. The X-band radar measurements also were generally successful in capturing the high spatial variability in convective rainfall, which caused post-fire debris flows.

Cifelli, R.; Matrosov, S. Y.; Gochis, D. J.; Kennedy, P.; Moody, J. A.

2011-12-01

123

Direct measurement of the combined effects of lichen, rainfall, and temperature onsilicate weathering  

USGS Publications Warehouse

A key uncertainty in models of the global carbonate-silicate cycle and long-term climate is the way that silicates weather under different climatologic conditions, and in the presence or absence of organic activity. Digital imaging of basalts in Hawaii resolves the coupling between temperature, rainfall, and weathering in the presence and absence of lichens. Activation energies for abiotic dissolution of plagioclase (23.1 ?? 2.5 kcal/mol) and olivine (21.3 ?? 2.7 kcal/mol) are similar to those measured in the laboratory, and are roughly double those measured from samples taken underneath lichen. Abiotic weathering rates appear to be proportional to rainfall. Dissolution of plagioclase and olivine underneath lichen is far more sensitive to rainfall.

Brady, P. V.; Dorn, R. I.; Brazel, A. J.; Clark, J.; Moore, R. B.; Glidewell, T.

1999-01-01

124

Direct measurement of the combined effects of lichen, rainfall, and temperature on silicate weathering  

SciTech Connect

A key uncertainty in models of the global carbonate-silicate cycle and long-term climate is the way that silicates weather under different climatologic conditions, and in the presence or absence of organic activity. Digital imaging of basalts in Hawaii resolves the coupling between temperature, rainfall, and weathering in the presence and absence of lichens. Activation energies for abiotic dissolution of plagioclase (23.1 {+-} 2.5 kcal/mol) and olivine (21.3 {+-} 2.7 kcal/mol) are similar to those measured in the laboratory, and are roughly double those measured from samples taken underneath lichen. Abiotic weathering rates appear to be proportional to rainfall. Dissolution of plagioclase and olivine underneath lichen is far more sensitive to rainfall.

Brady, P.V.; Dorn, R.I.; Brazel, A.J.; Clark, J.; Moore, R.B.; Glidewell, T.

1999-10-01

125

Post-processing rainfall forecasts from numerical weather prediction models for short-term streamflow forecasting  

NASA Astrophysics Data System (ADS)

Sub-daily ensemble rainfall forecasts that are bias free and reliably quantify forecast uncertainty are critical for flood and short-term ensemble streamflow forecasting. Post-processing of rainfall predictions from numerical weather prediction models is typically required to provide rainfall forecasts with these properties. In this paper, a new approach to generate ensemble rainfall forecasts by post-processing raw numerical weather prediction (NWP) rainfall predictions is introduced. The approach uses a simplified version of the Bayesian joint probability modelling approach to produce forecast probability distributions for individual locations and forecast lead times. Ensemble forecasts with appropriate spatial and temporal correlations are then generated by linking samples from the forecast probability distributions using the Schaake shuffle. The new approach is evaluated by applying it to post-process predictions from the ACCESS-R numerical weather prediction model at rain gauge locations in the Ovens catchment in southern Australia. The joint distribution of NWP predicted and observed rainfall is shown to be well described by the assumed log-sinh transformed bivariate normal distribution. Ensemble forecasts produced using the approach are shown to be more skilful than the raw NWP predictions both for individual forecast lead times and for cumulative totals throughout all forecast lead times. Skill increases result from the correction of not only the mean bias, but also biases conditional on the magnitude of the NWP rainfall prediction. The post-processed forecast ensembles are demonstrated to successfully discriminate between events and non-events for both small and large rainfall occurrences, and reliably quantify the forecast uncertainty. Future work will assess the efficacy of the post-processing method for a wider range of climatic conditions and also investigate the benefits of using post-processed rainfall forecasts for flood and short-term streamflow forecasting.

Robertson, D. E.; Shrestha, D. L.; Wang, Q. J.

2013-09-01

126

Linking ENSO and heavy rainfall events over Coastal British Columbia through a weather pattern classification  

NASA Astrophysics Data System (ADS)

Classifications of atmospheric weather patterns (WPs) are widely used for the description of the climate of a given region and are employed for many applications, such as weather forecasting, downscaling of global circulation model outputs and reconstruction of past climates. WP classifications were recently used to improve the statistical characterisation of heavy rainfall. In this context, bottom-up approaches, combining spatial distribution of heavy rainfall observations and geopotential height fields have been used to define WP classifications relevant for heavy rainfall statistical analysis. The definition of WPs at the synoptic scale creates an interesting variable which could be used as a link between the global scale of climate signals and the local scale of precipitation station measurements. We introduce here a new WP classification centred on the British Columbia Coastal region (Canada) and based on a bottom-up approach. Five contrasted WPs composed this classification, four rainy WPs and one non-rainy WP, the anticyclonic pattern. The four rainy WPs are mainly observed in the winter months (October to March), which is the period of heavy precipitation events in Coastal BC and is thus consistent with the local climatology. The combination of this WP classification with the seasonal description of rainfall is shown to be useful for splitting observed precipitation series into more homogeneous sub-samples and thus identifying, for each station, the synoptic situations that generate the highest hazard in terms of heavy rainfall events. El Niño Southern Oscillations significantly influence the frequency of occurrence of two Coastal BC WPs. Within each WP, ENSO seem to influence only the frequency of rainy events and not the magnitudes of heavy rainfall events. Consequently, MEWP heavy rainfall estimations do not show significant evolution of heavy rainfall behaviour between Niño and Niña winters. However, the WP approach captures the variability of the probability of occurrences of synoptic situations generating heavy rainfall depending on ENSO and opening interesting perspectives for the analysis of heavy rainfall distribution in a non-stationary context.

Brigode, P.; Mi?ovi?, Z.; Bernardara, P.; Paquet, E.; Garavaglia, F.; Gailhard, J.; Ribstein, P.

2012-10-01

127

Resolving SSM/I-ship radar rainfall discrepancies from AIP-3  

NASA Astrophysics Data System (ADS)

The third algorithm intercomparison project (AIP-3) involved rain estimates from more than 50 satellite rainfall algorithms and ground radar measurements within the Intensive Flux Array (IFA) over the equatorial western Pacific warm pool region during the Tropical Ocean Global Atmosphere coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Early results indicated that there was a systematic bias between rainrates from satellite passive microwave and ground radar measurements. The mean rainrate from radar measurements is about 50% underestimated compared to that from passive microwave-based retrieval algorithms. This paper is designed to analyze rain patterns from the Florida State University rain retrieval algorithm and radar measurements to understand physically the rain discrepancies. Results show that there is a clear range-dependent bias associated with the radar measurements. However, this range-dependent systematical bias is almost eliminated with the corrected radar rainrates. Results suggest that the effects from radar attenuation correction, calibration and beam filling are the major sources of rain discrepancies. This study demonstrates that rain retrievals based on satellite measurements from passive microwave radiometers such as the Special Sensor of Microwave Imager (SSM/I) are reliable, while rain estimates from ground radar measurements are correctable.

Yang, Song; Smith, Eric A.

2005-11-01

128

Rainfall Estimates from Radar, Satellite, Gauge, and Combinations: Intercomparison and Evaluation with Hydrologic Simulations  

NASA Astrophysics Data System (ADS)

Rainfall products from radar, satellite, rain gauges, and combinations (i.e., TRMM, PERSIANN, and NEXRAD) have been evaluated for a season of record rainfall in a heavily instrumented study domain in Oklahoma. Metrics describing algorithm performance are computed at seasonal, daily, and hourly scale, and as a function of rainfall intensity. In the second part of this study, we calibrated the Hydrology Laboratory - Distributed Hydrologic Model (HL-DHM) over the Ft. Cobb basin in OK using a 3-year archive of Micronet rain gauge data and USGS discharge observations. The rainfall estimates (with and without bias correction) from each algorithm were input to the independently calibrated hydrologic model and compared to observed streamflow for a 3-month period. The results indicate the performance of the evaluated rainfall algorithms is highly dependent on spatio-temporal scale and intensity of the storm event; i.e., one size does not fit all. We believe developers of rainfall algorithms can use the results presented in this study to optimize the contribution from available sensors to yield the most skillful multisensor rainfall products. This optimization step should consider the intended application of the rainfall products based on scale and intensity.

Flamig, Z.; Gourley, J. J.; Hong, Y.; Wang, J.

2009-12-01

129

Ground-based weather radar compatibility with digital radio-relay microwave systems  

NASA Astrophysics Data System (ADS)

The potential for ground-based weather radar (meteorological radar) interference to digital microwave systems in the common carrier bands of 3700 to 4200 MHz and 5925 to 6425 MHz is examined. Reported cases of interference to microwave common carrier systems from ground-based weather radar systems have increased due to the trend towards digital modulations. Because of this interference, the National Telecommunications and Information Administration, the Federal Communications Commission and the National Spectrum Managers Association formed an informal working group to investigate and document the potential problems. The existing and planned spectrum uses by ground-based weather radars and digital microwave systems are addressed as well as regulations and policy pertaining to their electromagnetic compatibility. Methods to mitigate the interference in both the radar transmitter and microwave receiver are also provided.

Gawthrop, P. E.; Patrick, G. M.

1990-03-01

130

Estimation of extreme floods of the River Meuse using a stochastic weather generator and a rainfall-runoff model  

Microsoft Academic Search

A stochastic weather generator has been developed to simulate long daily sequences of areal rainfall and station temperature for the Belgian and French sub-basins of the River Meuse. The weather generator is based on the principle of nearest-neighbour resampling. In this method rainfall and temperature data are sampled simultaneously from multiple historical records with replacement such that the temporal and

ROBERT LEANDER; ADRI BUISHAND; PAUL AALDERS; MARCEL DE WIT

2005-01-01

131

Terminal Doppler Weather Radar (TDWR) Build 5 Test and Evaluation Master Plan (TEMP).  

National Technical Information Service (NTIS)

This document presents the Terminal Doppler Weather Radar (TDWR), Build 5 enhancement, Test and Evaluation Master Plan (TEMP). This Build 5 TEMP identifies Operational Test and Evaluation (OTE) objectives, responsibilities, resources, schedules, and criti...

E. Turcich R. Cranston

1994-01-01

132

Spectral analyses of the dual polarization Doppler weather radar data  

NASA Astrophysics Data System (ADS)

Echoes in clear air from biological scatterers mixed within the resolution volumes over a large region are presented. These echoes were observed with the polarimetric prototype of the forthcoming WSR-88D weather radar. The study case occurred in the evening of September 7, 2004, at the beginning of the bird migrating season. Novel polarimetric spectral analyses are used for distinguishing signatures of birds and insects in multimodal spectra. These biological scatterers were present at the same time in the radar resolution volumes over a large area. Spectral techniques for (1) data censoring, (2) wind retrieval and (3) estimation of intrinsic values/functions of polarimetric variables for different types of scatterers are presented. The technique for data censoring in the frequency domain allows detection of weak signals. Censoring is performed on the level of spectral densities, allowing exposure of contributions to the spectrum from multiple types of scatterers. The spectral techniques for wind retrieval allow simultaneous estimation of wind from the data that are severely contaminated by migrating birds, and assessment of bird migration parameters. The intrinsic polarimetric signatures associated with the variety of scatterers can be evaluated using presented methodology. Algorithms for echo classification can be built on these. The possibilities of spectral processing using parametric estimation techniques are explored for resolving contributions to the Doppler spectrum from the three types of scatterers: passive wind tracers, actively flying insects and birds. A combination of parametric and non-parametric polarimetric spectral analyses is used to estimate the small bias introduced to the wind velocity by actively flying insects.

Bachmann, Svetlana Monakhova

133

Understanding the assimilation of dual-polarimetric radar observations and their impact on convective weather forecasting in mesoscale models  

NASA Astrophysics Data System (ADS)

Dual-polarimetric radars typically transmit/receive both horizontally and vertically polarized radio wave pulses. Owing to the enhanced measurement, dual-pol Doppler variables can provide more information about the liquid and solid cloud and precipitation particles, hence obtain more accurate estimate of rainfall and hydrometeors than non-polarimetric weather radars. The assimilation of dual-pol radar data may be a potential way to improve the performance of short-term forecast of numerical models. At present, not much effort has been given into the dual-pol radar data assimilation research field. With the ongoing upgrade of the current U.S. NEXRAD radar network to include dual-polarimetric capabilities, the dual-pol radar network will cover the whole country within the next couple years. The time is upon us to begin exploring how to best use the polarimetric data to improve forecast of severe storm and forecast initialization. The assimilation of dual-pol data for real cases is a challenging work. In this study, high-resolution (~1 km) WRF model and its 3DVAR data assimilation system are used. The dual-polarimetric radar data used in our studies was collected by the C-band Advanced Radar for Meteorological and Operational Research (ARMOR) radar (located at Huntsville International Airport (34.6804N, 86.7743W)), yet the emphasis now is toward using S-Band data from the upgraded NEXRAD network. Our presentation will highlight our recent work on assimilating the ARMOR radar data for real case convective storms, as well as new work using S-Band observations. Details of the methodology of data assimilation, the influences of different dual-pol variables on model initial condition and on the short-term prediction of precipitation, and the results for the real case storms, will be presented. In addition, before including a new observing system in an assimilation system, (dual-pol observations in this case) it is important to first assess the information content and uncertainty of the observations and forward model. An estimate of the information content in a set of observations requires knowledge of the relationship between measurements and forward observations. If the range of possible values of the measurements and forward observations is represented as a probability distribution, then the information content can be computed from the joint probability density function of the forward observations conditioned on the set of available measurements and on whatever forward model is chosen to relate them. Preliminary results will be shown toward understanding the information content of dual-polarimetric radar observations and their relationship to WRF model physics uncertainty.

Li, X.; Mecikalski, J. R.; Posselt, D. J.

2011-12-01

134

Validation of GOES-R Rainfall Rate Algorithm through TRMM PR and NIMROD radars  

NASA Astrophysics Data System (ADS)

The next generation Geostationary Operational Environmental Satellite (GOES-R) series will offer a continuation of current products and services and enable improved and new capabilities. The Advanced Baseline Imager (ABI) onboard the GOES-R platform has been designed to offer improved spatial and spectral resolution and temporal sampling, all of which should lead to enhanced capabilities for satellite-based rainfall estimation. The Hydrology Algorithm Team in the GOES-R Algorithm Working Group (AWG) has recommended, developed, and demonstrated an algorithm for the operational rainfall rate product, the GOES-R version of Self-Calibrating Multivariate Precipitation Retrieval (SCaMPR) algorithm. SCaMPR is an effort to combine the relative strengths of infrared (IR)-based and microwave (MW)-based estimates of precipitation. The GOES-R version of SCaMPR currently runs over Europe and Africa and surrounding oceans using the METEOSAT Spinning Enhanced Visible Infra-Red Imager (SEVIRI) data as a proxy for the ABI. Because the algorithm produces a field of instantaneous rainfall rates, radar data (both space-based and ground-based) is the only available source of data for validation against spec. Comparisons are made against Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data and Nimrod radar data over Western Europe obtained from the British Atmospheric Data Centre (BADC), respectively. This presentation will introduce the analysis methodology for estimating the precision and accuracy and provide the quantitative results in terms of the Functional and Performance Specifications.

Li, Y.; Kuligowski, R. J.

2010-12-01

135

Improving Tornado Warnings with the Federal Aviation Administration's Terminal Doppler Weather Radar  

Microsoft Academic Search

The potential role of the Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) to supplement the Weather Surveillance Radar-1988 Doppler (WSR-88D) for tornado detection is discussed. Compared to the WSR-88D, the TDWR has a narrower beam, lower scan angles, and faster update rates. The 11 August 1999 Salt Lake City, Utah, tornado is used as an illustration of the utility

Steven V. Vasiloff

2001-01-01

136

Fusing ultra-wideband radar and lidar for small UGV navigation in all-weather conditions  

Microsoft Academic Search

Autonomous small UGVs have the potential to greatly increase force multiplication capabilities for infantry units. In order for these UGVs to be useful on the battlefield, they must be able to operate under all-weather conditions. For the Daredevil Project, we have explored the use of ultra-wideband (UWB) radar, LIDAR, and stereo vision for all-weather navigation capabilities. UWB radar provides the

Brian Yamauchi

2010-01-01

137

DESIGN CONSIDERATIONS FOR AN X-BAND SPACED ANTENNA WEATHER RADAR  

Microsoft Academic Search

Having been routinely employed for ionospheric sounding and boundary layer profiling, the spaced-antenna method has recently attracted interest in the weather radar community. This paper presents design considerations for an X-band spaced-antenna phased array weather radar. The approach is based on a dual-polarized phased-array antenna currently in development at the University of Massachusetts, with phase scanning in azimuth and mechanical

V. Venkatesha; S. J. Frasier

138

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

Microsoft Academic Search

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

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

1996-01-01

139

Advances in Doppler Weather Radar Observing Methods and Data Processing Techniques.  

National Technical Information Service (NTIS)

A continuing objective of the Navy-sponsored, Doppler radar studies has been to develop the operational utility of the radar, both as a weather research tool and as an observing instrument useful for specialized, short-term forecasting. To fill this role ...

C. C. Easterbrook

1971-01-01

140

Classification of Weather Radar Images using Linguistic Decision Trees with Conditional Labelling  

Microsoft Academic Search

This paper focuses on the application of LID3 (Linguistic Decision Tree Induction Algorithm) to the classi- fication of weather radar images. In radar analysis a phe- nomenon known as Bright Band occurs. This essentially is an amplification in reflectivity due to melted snow and leads to overestimation of precipitation. It is therefore benefic ial to detect this Bright Band region

Daniel R. Mcculloch; Jonathan Lawry; Miguel A. Rico-ramirez; Ian D. Cluckie

2007-01-01

141

NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds  

Microsoft Academic Search

The 2006 eruption of Augustine Volcano, Alaska provided an exceptional opportunity to detect and measure explosive volcanic events and to track drifting volcanic clouds using WRS-88D (NEXRAD) weather radar data. Radar data complemented the real-time seismic monitoring by providing rapid confirmation of ash generation and cloud height. The explosive phase of the eruption consisted of thirteen discrete Vulcanian explosions from

D. J. Schneider; C. Scott; J. Wood; T. Hall

2006-01-01

142

Characterization of the Attenuation due to Rain Cell Fields applying Cellular Automata to Weather Radar Images  

Microsoft Academic Search

A straightforward linkage between rain cell dynamics in terms of reflectivity Z (dBz) or its equivalent rain rate R (mm\\/h) and satellite or terrestrial radiolink attenuation can be performed. This work focuses on the presentation of an approach for assessing and characterizing rain cell dynamics based exclusively on the analysis of the radar reflectivity scans recorded in weather radar image,

A. Nunez; V. Pastoriza; P. Marino; F. P. Fontan; U.-C. Fiebig

2006-01-01

143

Minimum operational performance standards for airborne weather and ground mapping pulsed radars  

NASA Astrophysics Data System (ADS)

Minimum operational performance standards for airborne weather and ground mapping pulsed radars, including both air carrier and large aircraft-type radar systems, are described. Those requirements and technologies pertinent to general aviation, where limitations on space and/or weight may apply are taken into account.

1980-11-01

144

Post processing rainfall forecasts from numerical weather prediction models for short term streamflow forecasting  

NASA Astrophysics Data System (ADS)

Sub-daily ensemble rainfall forecasts that are bias free and reliably quantify forecast uncertainty are critical for flood and short-term ensemble streamflow forecasting. Post processing of rainfall predictions from numerical weather prediction models is typically required to provide rainfall forecasts with these properties. In this paper, a new approach to generate ensemble rainfall forecasts by post processing raw NWP rainfall predictions is introduced. The approach uses a simplified version of the Bayesian joint probability modelling approach to produce forecast probability distributions for individual locations and forecast periods. Ensemble forecasts with appropriate spatial and temporal correlations are then generated by linking samples from the forecast probability distributions using the Schaake shuffle. The new approach is evaluated by applying it to post process predictions from the ACCESS-R numerical weather prediction model at rain gauge locations in the Ovens catchment in southern Australia. The joint distribution of NWP predicted and observed rainfall is shown to be well described by the assumed log-sinh transformed multivariate normal distribution. Ensemble forecasts produced using the approach are shown to be more skilful than the raw NWP predictions both for individual forecast periods and for cumulative totals throughout the forecast periods. Skill increases result from the correction of not only the mean bias, but also biases conditional on the magnitude of the NWP rainfall prediction. The post processed forecast ensembles are demonstrated to successfully discriminate between events and non-events for both small and large rainfall occurrences, and reliably quantify the forecast uncertainty. Future work will assess the efficacy of the post processing method for a wider range of climatic conditions and also investigate the benefits of using post processed rainfall forecast for flood and short term streamflow forecasting.

Robertson, D. E.; Shrestha, D. L.; Wang, Q. J.

2013-05-01

145

Nonlinear Modeling of Radar-Rainfall Errors at Different Time Scales  

NASA Astrophysics Data System (ADS)

There are large uncertainties associated with operational precipitation estimates produced by U.S. national network of WSR-88D radars. These errors are due to the measurement, sampling, and estimation aspects of the observational process. A quantitative description of radar-rainfall errors need to be empirically based and have the flexibility to account for different spatio-temporal scales, synoptic conditions and radar range effects. To describe the relation between true rainfall (RA) and radar-rainfall (RR), the authors developed a model characterized by two elements: a deterministic distortion function and a random component, which represents all the sources of uncertainty. The former can be modeled by a power law function, while the standard deviation of the latter by a hyperbolic function. For the temporal and spatial correlation of the random component, the authors have used a three-parameter exponential function. The fitting of these nonlinear expressions has been accomplished using a two-step methodology. First, a global grid search of the parameter space is performed. Then, the results are used as initial values for the Levenberg-Marquardt algorithm. In this study, the authors considered different time scales and investigated if any of the model components present scale-invariance properties. These results are based on a six-year sample of Level II data from the Oklahoma City WSR-88D radar site (KTLX) and processed through Build 4 of the Open Radar Product Generator Precipitation Processing System (PPS) that mimics NEXRAD algorithms. Although the RA values are unknown, they have been approximated with rain gauge observations from the Oklahoma Mesonet and Agricultural Research Service Micronet. The authors provide estimates of the magnitude of this approximation based on data obtained from a super-dense rain gauge network known as Oklahoma Piconet.

Villarini, G.; Krajewski, W. F.; Ciach, G. J.

2005-12-01

146

State-space adjustment of radar rainfall and skill score evaluation of stochastic volume forecasts in urban drainage systems.  

PubMed

Merging of radar rainfall data with rain gauge measurements is a common approach to overcome problems in deriving rain intensities from radar measurements. We extend an existing approach for adjustment of C-band radar data using state-space models and use the resulting rainfall intensities as input for forecasting outflow from two catchments in the Copenhagen area. Stochastic grey-box models are applied to create the runoff forecasts, providing us with not only a point forecast but also a quantification of the forecast uncertainty. Evaluating the results, we can show that using the adjusted radar data improves runoff forecasts compared with using the original radar data and that rain gauge measurements as forecast input are also outperformed. Combining the data merging approach with short-term rainfall forecasting algorithms may result in further improved runoff forecasts that can be used in real time control. PMID:23925186

Löwe, Roland; Mikkelsen, Peter Steen; Rasmussen, Michael R; Madsen, Henrik

2013-01-01

147

Prediction of extreme rainfall event using weather pattern recognition and support vector machine classifier  

NASA Astrophysics Data System (ADS)

A major component of flood alert broadcasting is the short-term prediction of extreme rainfall events, which remains a challenging task, even with the improvements of numerical weather prediction models. Such prediction is a high priority research challenge, specifically in highly urbanized areas like Mumbai, India, which is extremely prone to urban flooding. Here, we attempt to develop an algorithm based on a machine learning technique, support vector machine (SVM), to predict extreme rainfall with a lead time of 6-48 h in Mumbai, using mesoscale (20-200 km) and synoptic scale (200-2,000 km) weather patterns. The underlying hypothesis behind this algorithm is that the weather patterns before (6-48 h) extreme events are significantly different from those of normal weather days. The present algorithm attempts to identify those specific patterns for extreme events and applies SVM-based classifiers for extreme rainfall classification and prediction. Here, we develop the anomaly frequency method (AFM), where the predictors (and their patterns) for SVM are identified with the frequency of high anomaly values of weather variables at different pressure levels, which are present before extreme events, but absent for non-extreme conditions. We observe that weather patterns before the extreme rainfall events during nighttime (1800 to 0600Z) is different from those during daytime (0600 to 1800Z) and, accordingly, we develop a two-phase support vector classifier for extreme prediction. Though there are false alarms associated with this prediction method, the model predicts all the extreme events well in advance. The performance is compared with the state-of-the-art statistical technique fingerprinting approach and is observed to be better in terms of false alarm and prediction.

Nayak, Munir Ahmad; Ghosh, Subimal

2013-03-01

148

Analysis of Operational Alternatives to the Terminal Doppler Weather Radar (TDWR).  

National Technical Information Service (NTIS)

Possible alternatives to the Terminal Doppler Weather Radar (TDWR) are assessed. We consider both the low altitude wind shear detection service provided by TDWR and its role in reducing weather-related airport delays through its input to the Integrated Te...

M. E. Weber J. Y. Cho M. Robinson J. E. Evans

2007-01-01

149

Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational evaluation testing  

Microsoft Academic Search

The Terminal Doppler Weather Radar (TDWR) testbed was used at the Kansas City International (KCI) airport during the summer of 1989. The objective was to test and refine previous tested techniques for the automatic detection of low-altitude wind shear phenomena (specifically microbursts and gun fronts) and heavy precipitation in a midwest weather environment, as well as to assess possible new

J. E. Evans

1990-01-01

150

SINGULAR VECTOR METHOD ON SHORT-TERM RAINFALL PREDICTION USING RADAR FOR HYDROLOGIC ENSEMBLE PREDICTION  

NASA Astrophysics Data System (ADS)

Ensemble rainfall short-term prediction with flood simulation in urban river basin is presented. Considering the small scale of storm event, the radar echo extrapolation by translation model was used for predicting rainfall from X-band polarimetric radar. A new attempt of the ensemble prediction system by using initial condition perturbed by singular vector was introduced to find perturbations of advection vector, which linearly grow most rapidly. The methodology was demonstrated throughout case studies in Kofu urban river basin, Japan, with convective and stratiform precipitation system cases. SV found two leading perturbations over three hour prediction, giving five ensemble members. The members were subsequently considered as uncertain input of distributed hydrological model for developing ensemble flood prediction. Verified with observed data, this approach could serve as a reliable and effective system for operational flood disaster prevention in urban area.

Hapsari, Ratih Indri; Oishi, Satoru; Sunada, Kengo; Nakakita, Eiichi; Sano, Tetsuya

151

Resolving SSM\\/I-ship radar rainfall discrepancies from AIP3  

Microsoft Academic Search

The third algorithm intercomparison project (AIP-3) involved rain estimates from more than 50 satellite rainfall algorithms\\u000a and ground radar measurements within the Intensive Flux Array (IFA) over the equatorial western Pacific warm pool region during\\u000a the Tropical Ocean Global Atmosphere coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Early results indicated that\\u000a there was a systematic bias between rainrates from satellite passive

Song Yang; Eric A. Smith

2005-01-01

152

Measurement of rainfall path attenuation near nadir: A comparison of radar and radiometer methods at 13.8 GHz  

Microsoft Academic Search

Rain profile retrieval from spaceborne radar is difficult because of the presence of attenuation at the higher frequencies planned for these systems. One way to reduce the ambiguity in the retrieved rainfall profile is to use the path-integrated attenuation as a constraint. Two techniques for measuring the path-integrated attenuation have been proposed: the radar surface reference technique and microwave radiometry.

S. L. Durden; Z. S. Haddad; A. Kitiyakara; F. K. Li; A. B. Tanner

1994-01-01

153

On the scale-dependent propagation of hydrologic uncertainity using high-resolution X-band radar rainfall estimates  

Microsoft Academic Search

Radar precipitation estimates can improve hydrologic prediction over a range of spatial scales represented by both rural and urban basins. Flooding results from the combination of heavy precipitation and the distributed hydraulic and hydrologic characteristics of the basin. Accuracy and spatial scaling of radar estimated rainfall, and its impact at relevant hydrologic scales is an important determinant of hydrologic prediction

B. E. Vieux; J. M. Imgarten

154

QUANTITATIVE PRECIPITATION FORECASTING FOR A SMALL URBAN AREA: USE OF RADAR NOWCASTING  

Microsoft Academic Search

Quantitative Precipitation Forecasting (QPF) over urban areas is a challenging problem. Many attempts have been made to use weather radar to produce rainfall forecasts with lead times of a few hours ahead. In the UK, the Met Office has developed a stochastic probabilistic precipitation forecasting scheme (STEPS), which merges an extrapolation radar rainfall forecast with a high-resolution Numerical Weather Prediction

A. N. A. Schellart; M. A. Rico-Ramirez; S. Liguori; A. J. Saul

155

Assessment of the Statistical Characterization of Small-Scale Rainfall Variability from Radar: Analysis of TRMM Ground Validation Datasets  

Microsoft Academic Search

The main objective of this study is to assess the ability of radar-derived rainfall products to characterize the small-scale spatial variability of rainfall. The authors use independent datasets from high-quality dense rain gauge networks employed during the Texas and Florida Underflights (TEFLUN-B) and Tropical Rainfall Measuring Mission component of the Large-Scale Biosphere Atmosphere (TRMM-LBA) field experiments conducted by NASA in

Mekonnen Gebremichael; Witold F. Krajewski

2004-01-01

156

Linking ENSO and heavy rainfall events over coastal British Columbia through a weather pattern classification  

NASA Astrophysics Data System (ADS)

Classifications of atmospheric weather patterns (WPs) are widely used for the description of the climate of a given region and are employed for many applications, such as weather forecasting, downscaling of global circulation model outputs and reconstruction of past climates. WP classifications were recently used to improve the statistical characterisation of heavy rainfall. In this context, bottom-up approaches, combining spatial distribution of heavy rainfall observations and geopotential height fields have been used to define WP classifications relevant for heavy rainfall statistical analysis. The definition of WPs at the synoptic scale creates an interesting variable which could be used as a link between the global scale of climate signals and the local scale of precipitation station measurements. We introduce here a new WP classification centred on the British Columbia (BC) coastal region (Canada) and based on a bottom-up approach. Five contrasted WPs composed this classification, four rainy WPs and one non-rainy WP, the anticyclonic pattern. The four rainy WPs are mainly observed in the winter months (October to March), which is the period of heavy precipitation events in coastal BC and is thus consistent with the local climatology. The combination of this WP classification with the seasonal description of rainfall is shown to be useful for splitting observed precipitation series into more homogeneous sub-samples (i.e. sub-samples constituted by days having similar atmospheric circulation patterns) and thus identifying, for each station, the synoptic situations that generate the highest hazard in terms of heavy rainfall events. El Niño-Southern Oscillations (ENSO) significantly influence the frequency of occurrence of two coastal BC WPs. Within each WP, ENSO seem to influence only the frequency of rainy events and not the magnitudes of heavy rainfall events. Consequently, heavy rainfall estimations do not show significant evolution of heavy rainfall behaviour between Niño and Niña winters. However, the WP approach captures the variability of the probability of occurrences of synoptic situations generating heavy rainfall depending on ENSO and opening interesting perspectives for the analysis of heavy rainfall distribution in a non-stationary context.

Brigode, P.; Mi?ovi?, Z.; Bernardara, P.; Paquet, E.; Garavaglia, F.; Gailhard, J.; Ribstein, P.

2013-04-01

157

Reliability and robustness of rainfall compound distribution model based on weather pattern sub-sampling  

NASA Astrophysics Data System (ADS)

A new probabilistic model for daily rainfall, named MEWP (Multi Exponential Weather Pattern) distribution, has been introduced in Garavaglia et al. (2010). This model provides estimates of extreme rainfall quantiles using a mixture of exponential distributions. Each exponential distribution applies to a specific sub-sample of rainfall observations, corresponding to one of eight typical atmospheric circulation patterns that are relevant for France and the surrounding area. The aim of this paper is to validate the MEWP model by assessing its reliability and robustness with rainfall data from France, Spain and Switzerland. Data include 37 long series for the period 1904-2003, and a regional data set of 478 rain gauges for the period 1954-2005. Two complementary properties are investigated: (i) the reliability of estimates, i.e. the agreement between the estimated probabilities of exceedance and the actual exceedances observed on the dataset; (ii) the robustness of extreme quantiles and associated confidence intervals, assessed using various sub-samples of the long data series. New specific criteria are proposed to quantify reliability and robustness. The MEWP model is compared to standard models (seasonalised Generalised Extreme Value and Generalised Pareto distributions). In order to evaluate the suitability of the exponential model used for each weather pattern (WP), a general case of the MEWP distribution, using Generalized Pareto distributions for each WP, is also considered. Concerning the considered dataset, the exponential hypothesis of asymptotic behaviour of each seasonal and weather pattern rainfall records, appears to be reasonable. The results highlight : (i) the interest of WP sub-sampling that lead to significant improvement in reliability models performances; (ii) the low level of robustness of the models based on at-site estimation of shape parameter; (iii) the MEWP distribution proved to be robust and reliable, demonstrating the interest of the proposed approach.

Garavaglia, F.; Lang, M.; Paquet, E.; Gailhard, J.; Garçon, R.; Renard, B.

2011-02-01

158

Rainfall Downscaling by a Phase-Conserving, Nonlinearly-Transformed Autoregressive Model: Validation on Radar Precipitation Estimates  

NASA Astrophysics Data System (ADS)

The prediction of the small-scale spatio-temporal pattern of intense rainfall events is crucial for flood risk assessment in small catchments and urban areas. In the absence of a full deterministic modelling of small-scale rainfall, it is common practice to resort to the use of stochastic downscaling models to generate ensemble rainfall predictions to be used as inputs to rainfall-runoff models. Here we discuss a spatio-temporal downscaling procedure that we call the "Rain FARM: Rainfall Filtered AutoRegressive Model," based on a non-linear transformation of a linearly correlated (gaussian) field, and we validate this approach on a set of radar precipitation estimates. The Rain FARM procedure allows for reproducing the scaling properties (if any) of the rainfall pattern and it can be easily linked with meteorological forecasts produced by limited area meteorological models. We believe that this approach represents a significant improvement over commonly available models used for rainfall downscaling.

Rebora, N.; Ferraris, L.; von Hardenberg, J.; Provenzale, A.

2004-05-01

159

A super-fast scanning technique study for an on-airport weather radar  

Microsoft Academic Search

We assess the prospects for detecting a dry microburst core in the vicinity of an airport using a super-fast scanning (SFS) technique. In particular we propose a 20-beam SFS radar system and develop a system specification delivering a similar performance to a conventional mechanical scanning terminal Doppler weather radar (CMS-TDWR). The performance is compared in terms of the accuracy by

K. Lai; D. Longstaff; G. Callaghan

2001-01-01

160

Terminal Doppler Weather Radar Tornadic Vortex Signature Detection Algorithm.  

National Technical Information Service (NTIS)

An algorithm for real-time detection of tornadoes, using single-Doppler radar, is described. This algorithm searches for tornadic vortex signatures (TVSs) which are characterized by strong azimuthal shear in Doppler velocity fields. A TVS usually indicate...

S. V. Vasiloff A. Witt

1990-01-01

161

An Investigation on the Combined Effects of the Uncertainties in Radar-Rainfall Estimates and Flash Flood Guidance  

NASA Astrophysics Data System (ADS)

The Flash Flood Guidance System (FFGS) is an operational system which assists forecasters to issue flash flood warnings and watches over the conterminous United States. Currently it is a fully deterministic system: given a certain precipitation accumulation, flash flood warnings are issued depending on the exceedance of a certain threshold value (flash flood guidance). The aim of this study is to consider the effects of radar-rainfall and flash flood guidance threshold uncertainties. Earlier studies quantified uncertainties due to the estimation of the hydraulic and terrain characteristics and due to the hydrologic model parameters and initial state. To account for the uncertainties in the radar-rainfall input, the authors use an empirically-based ensemble generator of synthetic radar-rainfall fields. The generator accounts for radar range effects, synoptic conditions, different space-time resolutions, and the spatial and temporal dependence of the errors. Thus, the total effect of uncertainty in both the input and in the FFG can be assessed. The authors discuss the potential of transforming the FFGS into a fully probabilistic system. Using Monte Carlo simulation one can obtain precipitation-flash flood guidance joint probability distribution of flash flood occurrence. This joint probability distribution can be used in the forecasters decision making process. The authors consider a hypothetical example of flash flood occurrence in several small basins in Oklahoma, using hourly radar rainfall data from the Oklahoma City WSR-88D radar (KTLX).

Villarini, G.; Krajewski, W. F.; Georgakakos, K. P.; Ntelekos, A. A.

2006-05-01

162

NETWORK ARCHITECTURE FOR SMALL X-BAND WEATHER RADARS - TEST BED FOR AUTOMATIC INTERCALIBRATION AND NOWCASTING  

Microsoft Academic Search

1.ABSTRACT In recent years the use of small inexpensive,X- band,radars ,for meteorological ,and ,hydrological purposes,has increased,significantly. Compared,to the traditional C-band and S-band radars,the ,X-band ,weather ,radar ,has ,the advantage,of high,temporal,and spatial resolution and low financial cost; however, the trade off is attenuation,due ,to X-band ,technology ,and ,short range due to the higher spatial resolution. Inrelation,to quantitative ,precipitation estimation,(QPE) and ,forecasting

Lisbeth Pedersen; Niels Einar Jensen; Henrik Madsen

163

Detection and discrimination of fauna in the aerosphere using Doppler weather surveillance radar.  

PubMed

Organisms in the aerosphere have been detected by radar since its development in the 1940s. The national network of Doppler weather radars (WSR-88D) in the United States can readily detect birds, bats, and insects aloft. Level-II data from the radar contain information on the reflectivity and radial velocity of targets and on width of the spectrum (SD of radial velocities in a radar pulse volume). Information on reflectivity can be used to quantify density of organisms aloft and radial velocity can be used to discriminate different types of targets based on their air speeds. Spectral width can also provide some useful information when organisms with very different air speeds are aloft. Recent work with dual-polarization radar suggests that it may be useful for discriminating birds from insects in the aerosphere, but more development and biological validation are required. PMID:21669769

Gauthreaux, Sidney A; Livingston, John W; Belser, Carroll G

2008-05-08

164

High-resolution rainfall signatures on X-band Synthetic Aperture Radar imagery: model analysis and experimental validation  

NASA Astrophysics Data System (ADS)

Climate modelers need global precipitation measurements because the released latent heat distribution has a profound effect on the performance of such models. Precipitation measurements are also required to facilitate water management strategies by hydrologists, and managers of transportation, agricultural and flood relief agencies. Although precipitation measurements are widely available in technologically advanced countries, the measurement of precipitation over oceans, mountainous terrain and less developed regions leaves much to be desired. Since the 1980s much of our understanding of global precipitation has been provided by space-borne passive microwave radiometers and a combination of microwave and infrared passive measurements. Unfortunately space-borne microwave radiometers, even in combination with infrared sensors, have had limited success in retrieving precipitation over land because they rely heavily on the scattering properties of ice in the upper regions of precipitating clouds. Those scattering properties may be poorly related to surface rainfall rates. This limitation can be overcome over land by space-based radars operating at X or Ku band. The Ku band Precipitation Radar (PR) aboard the Tropical Rainfall Measurement Mission (TRMM) program has provided unique precipitation measurements over land. Mountainous terrain has presented challenges to both ground and space-based radars. Radar reflectivity measurements from PR are routinely removed within about 1 to 2 kilometers from mountainous surfaces to avoid ground clutter. If significant shallow precipitation or rain cells smaller than the 4 km horizontal resolution occur along mountain slopes, then such precipitation may be missed by PR. The measurement of light, small rain cells may also be impaired by the signal-to-noise ratio floor of the PR. A new opportunity to measure precipitation from space may be afforded by the forthcoming availability of several X-band Synthetic Aperture Radars (X-SARs). The TerraSAR-X (TSX) was launched on June 15, 2007 by the Deutsches Zentrum f. Luft u. Raumfahrt (DLR) and another X-SAR will be launched by 2009. The Constellation of Small Satellites for Mediterranean basin Observations (COSMO-SkyMed, CSK) will be launched by the Agenzia Spaziale Italiana (ASI) within 2009. The first of four of these satellites was launched by ASI on June 7, 2007. The Israeli Defense Ministry plans to launch yet another X-band SAR, the TecSAR SAR Technology Demonstration Satellite, later in 2009. Space-borne X-SARs are generally not designed for atmospheric observation. SARs are often considered "all weather" sensors. However, there is relevant theoretical and experimental evidence that X-band radar may be significantly affected by precipitation occurrence within the synthetically scanned area [9]-[13]. As a matter of fact, PR was designed at Ku band which is only 4 GHz away from X band. Several authors showed that X-SARs are more sensitive to rainfall effects than SARs operating at longer wavelengths, such as L and C bands [10]-[13]. For example, this was demonstrated by the Shuttle Missions STS-59 and 68 of 1994 and the STS-99 Shuttle Radar Topography Mission (SRTM) of 2000 carrying the first X-SAR along with L and C band SARs. Rainfall reflectivity at X-band may be enhanced by about 12 dB and the attenuation increased by about 4 dB when compared to C-band reflectivity and attenuation. The potential of X-SAR for precipitation retrieval is intriguing. They will probably be able to measure rainfall over land with greater sensitivity than from radiometers. The high spatial resolution (less than 100 m) of X-SARs can provide new insights into the structure of precipitating clouds with respect to PR and its future upgrades. X-SAR platforms could also significantly enhance the planned constellation of satellites carrying microwave radiometers and radars that will be part of the foreseen Global Precipitation Measurements (GPM) mission. These X-SAR satellites, then, may make a valuable contribution to our understanding of the hydrological

Marzano, F. S.; Mori, S.; Mugnai, A.; Weinman, J. A.

2009-04-01

165

Very high resolution precipitation climatologies from the Tropical Rainfall Measuring Mission precipitation radar  

NASA Astrophysics Data System (ADS)

To investigate processes related to the interaction of topography and precipitation, a tropics-wide (±36° latitude) high resolution (0.1°) ten year (1998-2007) rainfall climatology is presented from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) using algorithm 2A25 version 6 near-surface rain. We observe a tight coupling between precipitation and topography with distinct precipitation-topography relationships present in northwest South America and South Asia. An error model is developed by subsampling the TRMM Multi-satellite Precipitation Analysis as sampled by the PR. The error model predicts observed sampling error as a function of resolution, rain rate and sampling frequency with an r 2 of 0.82. This error model indicates that the precipitation climatology at 0.1° resolution does resolve precipitation gradients in regions with large average daily rain totals including the Andes, Western Ghats, and Himalaya.

Nesbitt, Stephen W.; Anders, Alison M.

2009-08-01

166

Application of the Cloude-Pottier decomposition to weather radar signatures  

NASA Astrophysics Data System (ADS)

In this paper we apply the Cloude-Pottier decomposition to Weather Radar Signatures. First, we present the results of a simulation carried out at the Chemnitz University of Technology and give the expected H-? values for different rain intensities. A comparison with standard radarmeteorological variables is also given. Then, first ever images of Entropy and Anisotropy are presented for clouds and precipitation. Experimental Data are from the POLDIRAD Weather Facility in Oberpfaffenhofen, Germany.

Galletti, M.; Chandra, M.; Pottier, E.; Ghorbani, A.

2005-05-01

167

Wideband Waveform Design principles for Solid-state Weather Radars  

SciTech Connect

The use of solid-state transmitter is becoming a key part of the strategy to realize a network of low cost electronically steered radars. However, solid-state transmitters have low peak powers and this necessitates the use of pulse compression waveforms. In this paper a frequency diversity wideband waveforms design is proposed to mitigate low sensitivity of solid-state transmitters. In addition, the waveforms mitigate the range eclipsing problem associated with long pulse compression. An analysis of the performance of pulse compression using mismatched compression filters designed to minimize side lobe levels is presented. The impact of range side lobe level on the retrieval of Doppler moments are presented. Realistic simulations are performed based on CSU-CHILL radar data and Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) radar data.

Bharadwaj, Nitin; Chandrasekar, V.

2012-01-01

168

Probabilistic forecasting of shallow, rainfall-triggered landslides using real-time numerical weather predictions  

NASA Astrophysics Data System (ADS)

A project established at the National Institute of Water and Atmospheric Research (NIWA) in New Zealand is aimed at developing a prototype of a real-time landslide forecasting system. The objective is to predict temporal changes in landslide probability for shallow, rainfall-triggered landslides, based on quantitative weather forecasts from numerical weather prediction models. Global weather forecasts from the United Kingdom Met Office (MO) Numerical Weather Prediction model (NWP) are coupled with a regional data assimilating NWP model (New Zealand Limited Area Model, NZLAM) to forecast atmospheric variables such as precipitation and temperature up to 48 h ahead for all of New Zealand. The weather forecasts are fed into a hydrologic model to predict development of soil moisture and groundwater levels. The forecasted catchment-scale patterns in soil moisture and soil saturation are then downscaled using topographic indices to predict soil moisture status at the local scale, and an infinite slope stability model is applied to determine the triggering soil water threshold at a local scale. The model uses uncertainty of soil parameters to produce probabilistic forecasts of spatio-temporal landslide occurrence 48~h ahead. The system was evaluated for a damaging landslide event in New Zealand. Comparison with landslide densities estimated from satellite imagery resulted in hit rates of 70-90%.

Schmidt, J.; Turek, G.; Clark, M. P.; Uddstrom, M.; Dymond, J. R.

2008-04-01

169

TDWR (Terminal Doppler Weather Radar) PRF (Pulse Repetition Frequency) selection criteria  

NASA Astrophysics Data System (ADS)

The Terminal Doppler Weather Radar (TDWR) system shall provide high quality Doppler radar data on weather phenomena near high traffic airports. These data shall be used in real time by automated TDWR algorithms to detect weather situations which may be hazardous to the safe operation of aircraft within the vicinity of the airport. One of the major factors which could cause the degradation of the quality of these TDWR data is obscuration by distant storm cells. This obscuration is caused by storms located beyond the range interval being sampled by the radar, yet whose radar echo ambiguously folds within the range interval of interest. These range aliased echoes could trigger false detections by the algorithms, and/or cause actual hazardous situations near the airport to remain undetected. By carefully selecting the pulse repetition frequency (PRF) of the radar, range obscuration from distant storms can be minimized over specified airport regions. This document describes techniques for predicting the obscuration as a function of PRF, and details the criteria which shall be used by the TDWR system to automatically and adaptively select an optimal PRF in order to minimize these obscuration effects.

Crocker, S. C.

1988-03-01

170

Applications of Meteorological Doppler Radar for Weather Surveillance near Air Terminals  

Microsoft Academic Search

Meteorological Doppler radar, heretofore a tool for research, can now be considered for operational applications. One important application is to provide data for air traffic controllers to identify weather that may be hazardous to aircraft in terminal areas. Its use at large commercial airports may be justified both by safety and by savings in fuel and operating costs that should

Richard Strauch

1979-01-01

171

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages  

Microsoft Academic Search

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TDWR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau

C. M. Shun; S. Y. Lau; O. S. M. Lee

2003-01-01

172

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages  

Microsoft Academic Search

A Terminal Doppler Weather Radar (TDWR) started operation in Hong Kong, China, in 1997 for monitoring wind shear associated with thunderstorms affecting the Hong Kong International Airport. The airport was built on land reclaimed from the sea and lies to the immediate north of the mountainous Lantau Island, which has hills rising to nearly 1000 m. Since 1997, the airport

C. M. Shun; S. Y. Lau; O. S. M. Lee

2003-01-01

173

Terminal Doppler Weather Radar (TDWR) observation of atmospheric flow over complex terrain during tropical cyclone passages  

Microsoft Academic Search

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TWDR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau

Chi M. Shun; Sharon S. Lau

2000-01-01

174

Terminal Doppler Weather Radar (TDWR) build 5 Test and Evaluation Master Plan (TEMP)  

Microsoft Academic Search

This document presents the Terminal Doppler Weather Radar (TDWR), Build 5 enhancement, Test and Evaluation Master Plan (TEMP). This Build 5 TEMP identifies Operational Test and Evaluation (OT&E) objectives, responsibilities, resources, schedules, and critical test issues. The Build 5 enhancement consists of a Build 5A which provides connectivity to the Low Level Wind Shear Alert System (LLWAS) 2, and a

Elizabeth Turcich; Robert Cranston

1994-01-01

175

Application research on intelligent pattern recognition methods in hail identification of weather radar  

Microsoft Academic Search

Firstly, advantages of the learning ability of intelligent pattern recognition models, which have been used in hail identification of weather radar based on echo parameters, is discussed. Then, structures and working principles of hail identification models which based on fuzzy neural network and support vector machines (SVM) are described respectively. Finally, effect validation of hail identification has been finished by

She Yong; Yu Lei; Wei Yi

2010-01-01

176

MicroRadarNet: A network of weather micro radars for the identification of local high resolution precipitation patterns  

NASA Astrophysics Data System (ADS)

In this paper, MicroRadarNet, a novel micro radar network for continuous, unattended meteorological monitoring is presented. Key aspects and constraints are introduced. Specific design strategies are highlighted, leading to the technological implementations of this wireless, low-cost, low power consumption sensor network.Raw spatial and temporal datasets are processed on-board in real-time, featuring a consistent evaluation of the signals from the sensors and optimizing the data loads to be transmitted. Network servers perform the final post-elaboration steps on the data streams coming from each unit. Final network products are meteorological mappings of weather events, monitored with high spatial and temporal resolution, and lastly served to the end user through any Web browser.This networked approach is shown to imply a sensible reduction of the overall operational costs, including management and maintenance aspects, if compared to the traditional long range monitoring strategy.Adoption of the TITAN storm identification and nowcasting engine is also here evaluated for in-loop integration within the MicroRadarNet data processing chain. A brief description of the engine workflow is provided, to present preliminary feasibility results and performance estimates. The outcomes were not so predictable, taking into account relevant operational differences between a Western Alps micro radar scenario and the long range radar context in the Denver region of Colorado. Finally, positive results from a set of case studies are discussed, motivating further refinements and integration activities.

Turso, S.; Paolella, S.; Gabella, M.; Perona, G.

2013-01-01

177

The Federal Aviation Administration/Massachusetts Institute of Technology (FAA/MIT) Lincoln Laboratory Doppler weather radar program  

NASA Astrophysics Data System (ADS)

The program focuses on providing real-time information on hazardous aviation weather to end users such as air traffic control and pilots. Existing systems will soon be replaced by a Next Generation Weather Radar (NEXRAD), which will be concerned with detecting such hazards as heavy rain and hail, turbulence, low-altitude wind shear, and mesocyclones and tornadoes. Other systems in process are the Central Weather Processor (CWP), and the terminal Doppler weather radar (TDWR). Weather measurements near Memphis are central to ongoing work, especially in the area of microbursts and wind shear.

Evans, James E.

1988-06-01

178

Contrasting Tropical Rainfall Regimes Using TRMM and Ground-Based Polarimetric Radar  

NASA Astrophysics Data System (ADS)

The NASA TRMM satellite has provided unprecedented data for over 11 years. TRMM precipitation products have advanced our understanding of tropical precipitation considerably. Field programs in the tropics, specifically TRMM-LBA (January-February 1999 in Brazil; a TRMM ground validation experiment) and NAME (North American Monsoon Experiment, summer 2004 along the west coast of Mexico) have provided opportunities to investigate the characteristics of precipitation using S-band polarimetric radar data. Both of these locales feature heavy, monsoon-like precipitation. However, there is significant variability in precipitation in these regions. In Brazil, two distinct rainfall regimes were observed. During "easterly" phase periods, precipitation was continental like, featuring deep, intense convection. During "westerly" periods, precipitation was more oceanic like, featuring weaker convection embedded in widespread stratiform precipitation. In NAME, precipitation variability was forced more by terrain, opposed to synoptic conditions, as was the case in Brazil. The National Center for Atmospheric Research S-pol radar was used to diagnose precipitation characteristics. Larger drops, larger ice mass aloft, and larger rain contents were found in the TRMM-LBA easterly phases compared to westerly events. For NAME, larger drops, larger ice mass aloft, and larger rain contents were found for coastal plain convection compared to convection over the higher terrain of the Sierra Madre Occidental or adjacent coastal waters. The effects of these differences on TRMM Precipitation Radar based rainfall estimates are investigated. These microphysical differences suggest the use of different Z-R estimators as a function of regime and elevation. It appears that the TRMM attenuation correction is inadequate for intense convection observed in these two regions.

Rutledge, S. A.; Cifelli, R.; Lang, T.; Nesbitt, S.

2009-04-01

179

Coupling Radar Rainfall Estimation and Hydrological Modelling For Flash-flood Hazard Mitigation  

NASA Astrophysics Data System (ADS)

Flood risk mitigation is accomplished through managing either or both the hazard and vulnerability. Flood hazard may be reduced through structural measures which alter the frequency of flood levels in the area. The vulnerability of a community to flood loss can be mitigated through changing or regulating land use and through flood warning and effective emergency response. When dealing with flash-flood hazard, it is gener- ally accepted that the most effective way (and in many instances the only affordable in a sustainable perspective) to mitigate the risk is by reducing the vulnerability of the involved communities, in particular by implementing flood warning systems and community self-help programs. However, both the inherent characteristics of the at- mospheric and hydrologic processes involved in flash-flooding and the changing soci- etal needs provide a tremendous challenge to traditional flood forecasting and warning concepts. In fact, the targets of these systems are traditionally localised like urbanised sectors or hydraulic structures. Given the small spatial scale that characterises flash floods and the development of dispersed urbanisation, transportation, green tourism and water sports, human lives and property are exposed to flash flood risk in a scat- tered manner. This must be taken into consideration in flash flood warning strategies and the investigated region should be considered as a whole and every section of the drainage network as a potential target for hydrological warnings. Radar technology offers the potential to provide information describing rain intensities almost contin- uously in time and space. Recent research results indicate that coupling radar infor- mation to distributed hydrologic modelling can provide hydrologic forecasts at all potentially flooded points of a region. Nevertheless, very few flood warning services use radar data more than on a qualitative basis. After a short review of current under- standing in this area, two issues are examined: advantages and caveats of using radar rainfall estimates in operational flash flood forecasting, methodological problems as- sociated to the use of hydrological models for distributed flash flood forecasting with rainfall input estimated from radar.

Borga, M.; Creutin, J. D.

180

A distributed model for slope stability analysis using radar detected rainfall intensity  

NASA Astrophysics Data System (ADS)

The term shallow landslides is widely used in literature to describe a slope movement of limited size that mainly develops in soils up to a maximum of a few meters. Shallow landslides are usually triggered by heavy rainfall because, as the water starts to infiltrate in the soil, the pore-water pressure increases so that the shear strength of the soil is reduced leading to slope failure. We have developed a distributed hydrological-geotechnical model for the forecasting of the temporal and spatial distribution of shallow landslides to be used as a warning system for civil protection purpose. The model uses radar detected rainfall intensity as the input for the hydrological simulation of the infiltration. Using the rainfall pattern detected by the radar is in fact possible to dynamically control the redistribution of groundwater pressure associated with transient infiltration of rain so as to infer the slope stability of the studied area. The model deals with both saturated and unsaturated conditions taking into account the effect of soil suction when the soil is not completely saturated. Two pilot sites have been chosen to develop and test this model: the Armea basin (Liguria, Italy) and the Ischia Island (Campania, Italy). In recent years several severe rainstorms have occurred in both these areas. In at least two cases these have triggered numerous shallow landslides that have caused victims and damaged roads, buildings and agricultural activities. In its current stage, the basic basin-scale model applied for predicting the probable location of shallow landslides involves several stand-alone components. The solution suggested by Iverson for the Richards equation is used to estimate the transient groundwater pressure head distribution according to radar detected rainfall intensity. A soil depth prediction scheme and a limit-equilibrium infinite slope stability algorithm are used to calculate the distributed factor of safety (FS) at different depths and to record the lowest value in the final output file. The additional ancillary data required have been collected during fieldwork. To test the effectiveness of the model, near-real time simulations have been performed in the two test sites using data measured during the past rainfall events: December 2006 for the Armea basin and April 2006 for the Island of Ischia. The landslides triggered by rainfall during these two events were known thanks to the data collected during the fieldwork and to the photointerpretation performed on satellite images. Through the analysis of the factor of safety maps obtained during these simulations, it has been possible to evaluate the behaviour of the model in response to different and complex rainfall patterns. Moreover, the comparison of the results with the new landslide inventory map, has provided a spatial validation of the model for the Armea basin.

Leoni, L.; Rossi, G.; Catani, F.

2009-04-01

181

Coupling a vertically looking K-band radar and a C-band weather radar to obtain a complete profile of reflectivity  

Microsoft Academic Search

In a project funded under the German Climate Research Programme (DEKLIM), data from novel ground-based sensors are combined with data of the German weather radar network in order to retrieve quantitative precipitation data over land and sea. Usually, rain gauge measurements have to be interpolated for areal precipitation. Alternatively, areal radar reflectivity measurements taken somewhere aloft are often forcefully adjusted

A. Wagner; J. Seltmann; M. Diederich; G. Peters

2003-01-01

182

Fusing ultra-wideband radar and lidar for small UGV navigation in all-weather conditions  

NASA Astrophysics Data System (ADS)

Autonomous small UGVs have the potential to greatly increase force multiplication capabilities for infantry units. In order for these UGVs to be useful on the battlefield, they must be able to operate under all-weather conditions. For the Daredevil Project, we have explored the use of ultra-wideband (UWB) radar, LIDAR, and stereo vision for all-weather navigation capabilities. UWB radar provides the capability to see through rain, snow, smoke, and fog. LIDAR and stereo vision provide greater accuracy and resolution in clear weather but has difficulty with precipitation and obscurants. We investigate the ways in which the sensor data from UWB radar, LIDAR, and stereo vision can be combined to provide improved performance over the use of a single sensor modality. Our research includes both traditional sensor fusion, where data from multiple sensors is combined in a single representation, and behavior-based sensor fusion, where the data from one sensor is used to activate and deactivate behaviors using other sensor modalities. We use traditional sensor fusion to combine LIDAR and stereo vision for improved obstacle avoidance in clear air, and we use behavior-based sensor fusion to select between radar-based and LIDAR/vision-based obstacle avoidance based on current environmental conditions.

Yamauchi, Brian

2010-04-01

183

Advanced clouds tracking for airborne weather radar & ground primary surveillance radar  

Microsoft Academic Search

A method for modeling and tracking convective clouds within radar images is presented. An object modeling approach is used, based on the extraction of either morphological or grayscale skeletons from 2-dimensionnal cross-section of 3-dimensional radar data. Grayscale skeletons are appropriate shape descriptors for non-rigid and heterogeneous objects, in which gray-level local maxima correspond to regions of interest. The modeling scheme

C. Costes; J.-P. Artis; F. Barbaresco

2010-01-01

184

Evaluating spatio-temporal representations in daily rainfall sequences from three stochastic multi-site weather generation approaches  

Microsoft Academic Search

Many hydrological and agricultural studies require simulations of weather variables reflecting observed spatial and temporal dependence at multiple point locations. This paper assesses three multi-site daily rainfall generators for their ability to model different spatio-temporal rainfall attributes over the study area. The approaches considered consist of a multi-site modified Markov model (MMM), a reordering method for reconstructing space–time variability, and

R. Mehrotra; Ashish Sharma

2009-01-01

185

Weathering-limited rainfall-triggered shallow mass movements in undisturbed steepland tropical rainforest  

NASA Astrophysics Data System (ADS)

Rainfall-triggered landslides in undisturbed tropical rainforests may have been underestimated as contributors to slope development and denudation in the past. Theoretically, ideal conditions for such geomorphic processes, i.e. steep slopes and frequent high magnitude and intensity rainfall events, occur in a number of tropical regions, particularly within Southeast Asia. Therefore, a high frequency of occurrence of shallow slope failures was expected in the undisturbed steeplands of southeast Brunei. Stability conditions of the steep planar slopes were examined using a deterministic modelling approach in order to examine the possibility that most slopes could not fail in response to rainfall because they did not possess a sufficiently thick mantle of residual soil. A simple hillslope hydrology model based on a soil moisture balance approach was used to simulate hillslope responses to measured and simulated rainfall events. The stability of saturated slopes could then be analysed using the infinite slope model, the input shear strength parameters for which were obtained from direct shear tests and then calibrated by back-analysis of a failure which occurred in late 1991. The findings suggest that any slope of 40° and steeper should fail several times every year in response to storm events, but that in reality most of the slopes have failed previously and have not yet regained a critical depth of residual soil. Some approximate values for rates of weathering and slope development suggest that any given slope will not fail at intervals of less than 10,000 years. Therefore, the occurrence of shallow failures will be infrequent but nevertheless significant in terms of regional denudation and ecological diversity.

Dykes, A. P.

2002-07-01

186

Link between rainfall-based weather patterns classification over British-Columbia and El Niño Southern Oscillations  

NASA Astrophysics Data System (ADS)

Classifications of atmospheric weather patterns (WP) are widely used for the description of the climate of a given region and are employed for many applications, such as weather forecasting, downscaling of Global Circulation Models outputs and reconstruction of past climates. WP classifications were recently used to improve the statistical characterization of heavy rainfall occurrences. In this context, bottom-up approaches, combining spatial distribution of heavy rainfall observations and geopotential height fields have been used to define WP classifications relevant for heavy rainfall statistical analysis (Garavaglia et al., 2010). The definition of weather patterns at the synoptic scale creates an interesting variable which could be used as a link between the global scale of climate signals and local scale of precipitation station measurements. We introduce here a new WP classification centred on British-Columbia costal region (Canada) and based on a bottom up approach. We show that it is useful for the statistical characterization of British Columbia heavy rainfall. Interestingly, the frequency of occurrence of the different WP has been identified as dependent on El Niño Southern Oscillations (ENSO). This significant link can be used to discriminate different extreme rainfall distributions for "El Niño" and "La Niña" years, showing the ability of the WP approach to take into account climate variability and opening interesting perspectives for the analysis of extreme rainfall distribution in non-stationary context.

Brigode, P.; Micovic, Z.; Bernardara, P.; Gailhard, J.; Paquet, E.; Garavaglia, F.; Ribstein, P.

2012-04-01

187

The Polarimetric Radar Estimation of Rainfall over the Amazon during TRMM-LBA  

NASA Astrophysics Data System (ADS)

The Tropical Rainfall Measuring Mission (TRMM) is a NASA satellite project initiated to address a gap in our ability to accurately observe detailed rainfall patterns over the tropical continents and oceans. To support TRMM, several field campaigns were conducted. The TRMM-LBA (Large-scale Biosphere Atmosphere) experiment was conducted over the southwestern region of the Amazon (state of Rondonia, Brazil) in order to provide detailed information on the precipitation characteristics in the interior of a tropical continent. Information from TRMM-LBA will be used for validation of TRMM satellite products and for initialization and validation of cloud-resolving models and passive microwave retrieval algorithms. During the TRMM-LBA field campaign, a variety of instrumentation was deployed during the wet season (January - February 1999) to measure rainfall including several rain gauge networks, disdrometers, and the S-band polarimetric (NCAR S-POL) research radar. The focus of this study will be on the estimation, validation, and uncertainty of rain rate estimates derived from the NCAR S-POL radar. The S-POL data were carefully corrected for the presence of clear-air echo, ground clutter, anomalous propagation, partial beam blocking, precipitation attenuation, and calibration biases by applying polarimetric radar methods. Using an optimal polarimetric radar technique, maps of rain rate have been calculated from observations of S-POL horizontal reflectivity (Zh), differential reflectivity (Zdr), and specific differential phase (Kdp) every ten minutes from 10 January to 28 February 1999. From these rain rate estimates, daily and 30-day rain accumulation maps have been compiled. When validated against the rain gauge totals, preliminary S-POL estimates of monthly rainfall, which utilized the equilibrium raindrop shape model of Beard and Chuang (1987), have a negative bias error in the range of -5% to -11% and a standard error of 14% to 20%. We will compare these results with the methodology of Gorgucci et al. (2000, 2001), which attempts to account for the variability in the raindrop shape-size relation. Some practical issues involved in the implementation of this method will be discussed. Finally, we will present preliminary attempts to estimate the uncertainty of the rain rates at each grid point following Bringi and Chandrasekar (2001, Ch. 8). As in BC2001, the uncertainty will be expressed as the standard deviation of R divided by R (? (R)/R). The uncertainty will be based on 1) the polarimetric algorithm and measurements utilized in the optimal rain rate approach at each point, 2) an estimate of error associated with measurement error as a function of rain rate, and 3) an estimate of the error associated with the utilized algorithm as a function of rain rate. Since there is inherent ambiguity in estimating uncertainty in this manner, we will also experiment with converting ? (R)/R into a qualitative uncertainty index (UI) ranging from 1 to 5, where 1 is very certain and 5 is very uncertain.

Carey, L. D.; Cifelli, R.; Petersen, W. A.; Rutledge, S. A.

2002-05-01

188

Terminal Doppler Weather Radar Build 5A Operational Test and Evaluation (OTE) Integration and OTE Operational Test Plan.  

National Technical Information Service (NTIS)

The Terminal Doppler Weather Radar (TDWR) Build 5A Enhancement Operational Test and Evaluation (OTE) Integration and OTE Operational Test Plan provides the overall philosophy and approach to Build 5A OTE testing, and identifies OTE objectives responsibili...

R. Martinez P. Guthlein S. Viveiros D. Wedge

1994-01-01

189

Radar Detected Rainfall Intensity As An Input For Shallow Landslides Slope Stability Model  

NASA Astrophysics Data System (ADS)

The term "shallow landslides" is widely used in literature to describe a slope movement of limited size that mainly develops in soils up to a maximum of a few meters. Shallow landslides are usually triggered by heavy rainfall because, as the water starts to infiltrate in the soil, the pore-water pressure increases so that the shear strength of the soil is reduced leading to slope failure. For this work we have developed a distributed hydrological-geotechnical model for the forecasting of the temporal and spatial distribution of shallow landslide to be used as a warning system for civil protection purpose. The main goal of this work is the use of radar detected rainfall intensity as the input for the hydrological simulation of the infiltration. Using the rainfall pattern detected by the radar is in fact possible to dynamically control the redistribution of groundwater pressure associated with transient infiltration of rain so as to infer the slope stability of the studied area. The model deals with both saturated and unsaturated conditions. Two pilot sites have been chosen to develop and test this model: the Armea basin (Liguria, Italy) and the Ischia Island (Campania, Italy). In recent years several severe rainstorms have occurred in both these areas. In at least two cases these have triggered numerous shallow landslides that have caused victims and damaged roads, buildings and agricultural activities. In its current stage the basic basin-scale model applied for predicting the probable location of shallow landslides involves several stand-alone components. A module for estimating the groundwater pressure head distribution according to radar detected rainfall intensity, a soil depth prediction scheme and a limit-equilibrium infinite slope stability algorithm which produces a factor of safety (FS). The additional ancillary data required have been collected during the field work. The single components are seamlessly integrated into a system that automatically publishes constantly updated FS values to a WebGIS in near-real- time so that local administrators responsible for public safety can access and download the data from the internet. This system has been running for a few months and is now being validated. Several types of problems hinder a correct validation of the system. One major obstacle was overcome when major storms triggered several tens of soil slips in December 2006 for the Armea basin and in April 2006 for Ischia. This events provided both the necessary rainfall data for the soil saturation component, which until then for previous occurred landslides was lacking, and a new landslide inventory for comparison with the FS produced by the slope stability model for the same event. The inventory was derived from a newly acquired VHR satellite image. Another important aspect of the research being performed regards the assessment of the relative importance of the different parameters involved in the limit-equilibrium infinite slope stability model. This statistical sensitivity analysis has the aim of determining which errors in the input variables slope gradient, soil depth, soil saturation, cohesion and angle of internal friction produce the largest errors in the output FS values. Preliminary results indicate the importance of topographic attributes and of soil depth.

Leoni, L.; Rossi, G.; Catani, F.; Righini, G.; Rudari, R.

2008-12-01

190

Identification of Aviation Weather Hazards Based on the Integration of Radar and Lightning Data.  

NASA Astrophysics Data System (ADS)

The National Weather Service Eastern Region is carrying out a national risk-reduction exercise at the Baltimore-Washington Forecast Office in Sterling, Virginia. The primary objective of this project is to integrate information from remote sensor technologies to produce comprehensive state-of-the-atmosphere reports that promote aviation safety. Techniques have been developed and tested to identify aviation-oriented hazardous weather based on data from conventional radars, a national lightning detection network, and collateral observations from new Automated Surface Observing System (ASOS) sites that are being deployed throughout the nation. From July through September 1993, an experimental observational product to identify convective activity within 30 n mi of six airports from southern Virginia to Delaware was transmitted three times each hour to personnel at Weather Service Offices and Center Weather Service Units and to the meteorologists and flight dispatchers of five major air carriers. This user-oriented evaluation and the associated statistical analysis has provided important feedback to assess the utility of the product as a supplement to ASOS. Integration of information from several products generated by the new Doppler radar at Sterling with lightning network data is being pursued for the second phase of the project. The National Weather Service will determine the viability of this approach to generate products to routinely supplement the information provided by ASOS on either a national or a local basis.

Stern, Andrew D.; Brady, Raymond H., III; Moore, Patrick D.; Carter, Gary M.

1994-12-01

191

Technological challenges of a multifunction active phased array radar for weather, air traffic control and security applications  

Microsoft Academic Search

By means of Active Phased Array techniques, an integrated target\\/weather surveillance at medium range, i.e. for Terminal Manoeuvre Area in the frame of ATC and regional weather monitoring, is possible and affordable provided that cost reduction for Transmit\\/Receive modules makes phased array radar affordable to civilian users. The MPAR (Multifunction Phased Array Radar) architecture allows a single equipment to satisfy

G. Galati; G. Pavan; S. Scopelliti; L. Infante

2010-01-01

192

Distributed Model Complexity Versus Radar-Rainfall Input Uncertainty for Flow Simulation  

NASA Astrophysics Data System (ADS)

The NOAA-organized Distributed Model Intercomparison Project (DMIP) has created the opportunity to study the issues pertaining to flow simulation by distributed hydrologic models with varying formulation and complexity. In this study, we examine the response of a given distributed hydrologic model under realistic conditions of uncertainty in radar-rainfall input and parameters. We extend the research reported in Carpenter et al., 2001, by (a) refining the characterization of the input uncertainty, (b) allowing for uncertainty in several soil-model parameters simultaneously, and (c) performing an inter comparison of flow simulations generated by spatially distributed and spatially lumped models to assess the likelihood that a more complex model structure would lead to significantly different flow simulations given the expected model input uncertainty. A Monte Carlo framework is used to perform the sensitivity runs and probabilistic measures are employed to determine significant sensitivities in simulated flow ensembles. The application watersheds include the DMIP basins: the Illinois River in Oklahoma, the Blue River in Oklahoma and the Elk River in Missouri. The sensitivity results are summarized in terms of simulated flow variability and assessed with regard to the basin size, peak flow, and input uncertainty. Reference: Carpenter, T.M., K.P. Georgakakos, and J.A. Sperfslage, 2001: On the parametric and NEXRAD-radar sensitivities of a distributed hydrologic model suitable for operational use. J. Hydrology, 253, 169-193.

Carpenter, T. M.; Georgakakos, K. P.

2002-05-01

193

Performances comparison of pulse pair and wavelets methods for the pulse Doppler weather radar spectrum  

NASA Astrophysics Data System (ADS)

In the civilian aviation field, the radar detection of hazardous weather phenomena (winds) is very important. This detection will allow the avoidance of these phenomena and consequently will enhance the safety of flights. In this work, we have used the wavelets method to estimate the mean velocity of winds. The results showed that the application of this method is promising compared with the classical estimators (pulse pair, Fourier)

Lagha, M.; Tikhemirine, M.; Bergheul, S.; Rezoug, T.; Bettayeb, M.

2010-02-01

194

Recognition and forecast of severe weather evolution with radar and satellite information  

NASA Astrophysics Data System (ADS)

This work is the case study based on the remote sensing data about squall line in Shanghai at July 12 2004, focus on the analysis on Doppler radar echo products, satellite image, surface and sounding data, automatic weather station data. The purpose is to reveal the special structure of the squall line, recognize the evolution of strong convection with multi-scale information, and find the prediction mechanism for reducing disaster on mankind.

Wei, Ming; Niu, Ben; Xia, Wangping; Zhan, Yating

2009-10-01

195

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part I: Clutter Filtering  

Microsoft Academic Search

Multiple pulse repetition interval (multi-PRI) transmission is part of an adaptive signal transmission and processing algorithm being developed to aggressively combat range-velocity ambiguity in weather radars. In the past, operational use of multi-PRI pulse trains has been hampered due to the difficulty in clutter filtering. This paper presents finite impulse response clutter filter designs for multi-PRI signals with excel- lent

John Y. N. Cho; Edward S. Chornoboy

2005-01-01

196

Practical Algorithms for Mean Velocity Estimation in Pulse Doppler Weather Radars Using a Small Number of Samples  

Microsoft Academic Search

Doppler weather radars with fast scanning rates must estimate spectral moments based on a small number of echo samples. This paper concerns the estimation of mean Doppler velocity in a coherent radar using a short complex time series. Specific results are presented based on 16 samples. A wide range of signal-to-noise ratios are considered, and attention is given to ease

Pravas R. Mahapatra; Dusan S. ZrniC

1983-01-01

197

Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational evaluation testing  

NASA Astrophysics Data System (ADS)

The Terminal Doppler Weather Radar (TDWR) testbed was used at the Kansas City International (KCI) airport during the summer of 1989. The objective was to test and refine previous tested techniques for the automatic detection of low-altitude wind shear phenomena (specifically microbursts and gun fronts) and heavy precipitation in a midwest weather environment, as well as to assess possible new products such as storm movement predictions. A successful operation evaluation of the TDWR products took place at the KCI tower and terminal radar control room (TRACON). Several supervisor and controller display refinements were assessed as effective. The system was successful in terms of aircraft at KCI avoiding wind shear encounters during the operational period, and it was assessed as very good in usefulness for continuing operation by the KCI air traffic control (ATC) personnel. The probability of detection for microbursts was substantially better than that in Denver. However, the false-alarm probability was found to be substantially higher in Kansas City due to a combination of weather and clutter phenomena. By optimizing the site-adaptation capabilities of the TDWR meteorological and data quality algorithms, the required false-alarm probability was achieved. The gust front performance was generally poorer than in Denver due to a combination of unfavorable radar-airport-gust front geometry of false alarms induced by low-level jets. Gust front algorithm refinements which should provide improved performance are discussed.

Evans, J. E.

1990-08-01

198

Product-error-driven generator of probable rainfall conditioned on WSR-88D precipitation estimates  

NASA Astrophysics Data System (ADS)

The existence of large errors in precipitation products delivered by the network of Weather Surveillance Radar, 1988 Doppler (WSR-88D) radars is broadly recognized. However, their quantitative characteristics remain poorly understood. Recently, the authors developed a functional-statistical model that quantifies the relation between radar rainfall and the corresponding true rainfall in a way that is applicable to the probabilistic quantitative precipitation estimation planned for future use by the U.S. National Weather Service. The model consists of a deterministic distortion function and a random uncertainty factor, both conditioned on given radar rainfall values. It also accounts for the spatiotemporal correlations in the random uncertainty factor. The model components were estimated on the basis of a 6-year-long data sample that considers the effects of seasons, range from radar, and time scales. In this study, the authors present two different applications of the aforementioned uncertainty model: (1) the estimation of rainfall probability maps and (2) the generation of radar rainfall ensembles. In the former, maps of the rainfall exceedance probability for any threshold are produced, given a radar rainfall map. We also present the analytical derivation of the exceedance probability maps at coarser spatial scales. In the latter, the users can generate ensembles of probable true rainfall fields that are consistent with the observed radar rainfall and its error structure. Simulation of the random component is based on the Cholesky decomposition method. Finally, the authors discuss possible uses of these applications in hydrology and hydroclimatology.

Villarini, Gabriele; Krajewski, Witold F.; Ciach, Grzegorz J.; Zimmerman, Dale L.

2009-01-01

199

Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar  

NASA Astrophysics Data System (ADS)

Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and comparison of TRMM PR statistics with ground-based radar has been extended to other regions of the globe. The Australian Bureau of Meteorology C-band polarimetric radar C-Pol has been collecting data in Darwin, Australia for over a decade. The Darwin region affords the opportunity to look at precipitation characteristics over land and ocean, as well as variability associated with monsoon and break periods over long periods of time. The polarimetric X-band radar XPort was stationed in West Africa at a field site in Benin during the 2006 and 2007 African monsoon periods, where differences in rainfall associated with African Easterly Wave (AEW) passages and non-AEW periods can be examined. Similar comparisons between TRMM PR and ground based polarimetric radars will also be reported for these regions.

Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

2010-05-01

200

The Federal Aviation Administration\\/Massachusetts Institute of Technology (FAA\\/MIT) Lincoln Laboratory Doppler weather radar program  

Microsoft Academic Search

The program focuses on providing real-time information on hazardous aviation weather to end users such as air traffic control and pilots. Existing systems will soon be replaced by a Next Generation Weather Radar (NEXRAD), which will be concerned with detecting such hazards as heavy rain and hail, turbulence, low-altitude wind shear, and mesocyclones and tornadoes. Other systems in process are

James E. Evans

1988-01-01

201

Weather  

NSDL National Science Digital Library

This project will help you understand the weather and investigate weather interactively. What are the components of weather? How do you measure weather? Investigate the WeatherScholastic: Weather WatchWeatherWeather Center for Our 4th Grade ...

Lai, Ms.

2007-02-08

202

Offshore next generation weather radar (NEXRAD) test and evaluation master plan (TEMP)  

NASA Astrophysics Data System (ADS)

This document provides the test philosophy and approach for the Offshore Next Generation Weather Radar (NEXRAD) Test and Evaluation Master Plan (TEMP). The NEXRAD differs from the typical Federal Aviation Administration (FAA) weather radar acquisition in that it is jointly funded by the Department of Defense (DOD), the Department of Commerce (DOC), and the Department of Transportation (DOT). These three agencies chartered the Joint System Program Office (JSPO) to manage the NEXRAD development and subsequent test programs. JSPO has deployed 70 single-channel radar systems across the continental United States (CONUS). The FAA is deploying NEXRAD systems at non-CONUS (offshore) locations such as Alaska, Hawaii, and the Caribbean. The FAA Offshore NEXRAD will have a redundant configuration and a Remote Monitoring Subsystem (EMS). A total of 14 Offshore NEXRAD's will be procured under this acquisition: 3 in the Caribbean, 4 in Hawaii, and 7 in Alaska. Funding constraints will limit the acquisition to seven NEXRAD's in the 1994-1995 timeframe.

Martinez, Radame; Cranston, Robert; Porcello, John

1995-01-01

203

Improving Tornado Warnings with the Federal Aviation Administration's Terminal Doppler Weather Radar.  

NASA Astrophysics Data System (ADS)

The potential role of the Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) to supplement the Weather Surveillance Radar-1988 Doppler (WSR-88D) for tornado detection is discussed. Compared to the WSR-88D, the TDWR has a narrower beam, lower scan angles, and faster update rates. The 11 August 1999 Salt Lake City, Utah, tornado is used as an illustration of the utility of the TDWR. The Salt Lake City TDWR was much closer to the tornado than the WSR-88D and the WSR-88D was 750 m higher than the TDWR. Because the tornado developed rapidly upward from a surface convergence line, the TDWR detected the formation earlier than the WSR-88D. Also, the vortex signatures associated with the tornado were much better defined by the TDWR.The enhanced spatial and temporal coverage provided by the TDWR network is shown. A significant improvement in tornado detection, as well as other low-altitude phenomena, would be gained. However, ground clutter and signal attenuation can degrade coverage. Ongoing efforts by the National Weather Service to incorporate TDWR data into operations are described.

Vasiloff, Steven V.

2001-05-01

204

A radar data based short-term rainfall prediction model for urban areas — a simulation using meso-scale meteorological modelling  

Microsoft Academic Search

A conceptual short-term rainfall prediction model for urban catchments is presented. The only input variables are surface rainfall and vertically integrated liquid water content (VIL), both measurable by radar on site. The forecast is based on simple mass balancing of water within air columns and the spatial advection of the variables using information from consecutive time steps. This paper describes

J. Thielen; B Boudevillain; H Andrieu

2000-01-01

205

Coupling a vertically looking K-band radar and a C-band weather radar to obtain a complete profile of reflectivity  

NASA Astrophysics Data System (ADS)

In a project funded under the German Climate Research Programme (DEKLIM), data from novel ground-based sensors are combined with data of the German weather radar network in order to retrieve quantitative precipitation data over land and sea. Usually, rain gauge measurements have to be interpolated for areal precipitation. Alternatively, areal radar reflectivity measurements taken somewhere aloft are often forcefully adjusted to rain gauge data at the ground not considering the low areal representativity of the latter. In this project, ambiguities of the relation between radar reflectivity and surface precipitation rates shall be mitigated on a physical basis using auxiliary profile measurements. A low-power vertically pointing K-Band Doppler micro rain radar (MRR) provides profiles of Doppler spectra from precipitation in the lower 3000 meters of the atmosphere. Thus, information about the modification of precipitation on its way to the ground is gained, e.g. the vertical reflectivity profile (VRP) including the melting zone. Disdrometers and ombrometers are used to convert MRR data into rain rates at the bottom of this column. At its top, the VRP has to be matched to the areal measurement of the weather radar. To ensure continuity at this point, a comparison has been conducted between the Rostock weather radar at the German Baltic coast and the MRR at Zingst 50 kms northeast. The MRR Doppler spectra are converted to drop-size-distributions from which the reflectivity factor Z can be derived. For an eight-weeks-period, this is directly compared to weather radar measurements at C-band. The best correlation achieved using dBZ time series was 0.912.

Wagner, A.; Seltmann, J.; Diederich, M.; Peters, G.

2003-04-01

206

Use Of Radar-Rainfall Data for the Southwest Coastal Louisiana Feasibility Study: Regional Scale Hydrologic and Salinity Modeling and Management Scenario Analysis for Chenier Plain  

NASA Astrophysics Data System (ADS)

The Chenier Plain, in Southwest Louisiana, extends from Vermilion Bay to Sabine Lake in southeast Texas. It has great economic, industrial, recreational, and ecological value. Over the years, human activities such as dredging ship channels and access canals, building roads, levees, and hydraulic structures have altered the hydrology of the Chenier Plain. These alterations have affected the fragile equilibrium of the marsh ecology. If no action is taken to restore the Chenier Plain, land loss through conversion of marsh to open water would continue. The Southwest Coastal Louisiana Feasibility Study aims at evaluating proposed protection and restoration measures and ultimately submitting a comprehensive plan to protect and preserve the Chenier Plain at the regional scale. The proposed alternatives include marsh creation, terracing, shoreline protection, and freshwater introduction and salinity control structures. A regional scale hydrodynamic and salinity transport model was developed to screen and assess the proposed restoration measures. A critical component of this modeling effort is local rainfall. The strong spatial variability and limited availability of ground-level precipitation measurements limited our ability to capture local rainfall. Thus, a radar-based rainfall product was used as a viable alternative to the rain gauges. These estimates are based on the National Weather Service from the Multi-Sensor Precipitation Estimator (MPE) algorithm. Since the model was used to perform long-term (yearly) simulations, the 4x4 km2 MPE estimates were represented as daily accumulations. The use of the radar-rainfall product data improved the model performance especially on our ability to capture the spatial and temporal variations of salinity. Overall, the model is improving our understanding of the circulation patterns and salinity regimes of the region. The circulation model used here is the MIKE FLOOD software (Danish Hydraulic Institute, DHI 2008) which dynamically integrates a two-dimensional grid (MIKE 21) and a one-dimensional channel flow simulation tool (MIKE 11). The model was successfully calibrated and validated using water level and salinity data collected at monitoring stations in the channels and throughout the marsh areas. The model prediction agreed favorably with the field measurements at the daily and monthly average scale. Uncertainties in the bathymetric data, open water boundary, as well as the operation schedules of water control structures prevented the model from being validated at a higher temporal frequency. Ongoing monitoring efforts are being used to minimize these uncertainties.

Meselhe, E. A.; Michot, B.; Chen, C.; Habib, E. H.

2011-12-01

207

An automatic identification of clutter and anomalous propagation in polarization-diversity weather radar data using neural networks  

Microsoft Academic Search

Radar polarization measurements have mostly been used to improve rainfall estimation and hydrometeor characterization. The authors extend the use of such measurements to the problem of ground clutter recognition, including the case when this problem is associated with anomalous propagation of the electromagnetic wave. They present a methodology used for recognizing both clutter and meteorological targets. The methodology is based

Reinaldo B. da Silveira; Anthony Roy Holt

2001-01-01

208

Terminal Doppler Weather Radar (TDWR) build 5 Test and Evaluation Master Plan (TEMP)  

NASA Astrophysics Data System (ADS)

This document presents the Terminal Doppler Weather Radar (TDWR), Build 5 enhancement, Test and Evaluation Master Plan (TEMP). This Build 5 TEMP identifies Operational Test and Evaluation (OT&E) objectives, responsibilities, resources, schedules, and critical test issues. The Build 5 enhancement consists of a Build 5A which provides connectivity to the Low Level Wind Shear Alert System (LLWAS) 2, and a Build 5B which provides connectivity to an LLWAS III. Build 5A displays LLWAS 2 wind data along with TDWR hazardous weather data on TDWR Geographic Situation Displays (GSD) and Ribbon Display Terminals (RDT). Build 5B provides additional capabilities such as having a Microburst Shear Integration Algorithm (MSIA), TDWR/LLWAS 3 Integration Algorithm, 15-day archiving and TDWR, LLWAS 2 and LLWAS 3 data integration.

Turcich, Elizabeth; Cranston, Robert

1994-05-01

209

Monthly and seasonal streamflow forecasts using rainfall-runoff modeling and historical weather data  

Microsoft Academic Search

Rainfall-runoff models can reliably quantify catchment initial conditionsCatchment states and resampled historical rainfall enable skillful streamflow forecastWhole ensemble of historical forcings leads to the best streamflow forecasts

Enli Wang; Yongqiang Zhang; Jiangmei Luo; Francis H. S. Chiew; Q. J. Wang

2011-01-01

210

Forecasting River Uruguay flow using rainfall forecasts from a regional weather-prediction model  

Microsoft Academic Search

The use of quantitative rainfall forecasts as input to a rainfall-runoff model, thereby extending the lead-time of flow forecasts, is relatively new. This paper presents results from a study in which real-time river flow forecasts were calculated for the River Uruguay basin lying within southern Brazil, using a method based on observed rainfall, quantitative forecasts of rainfall given by a

Walter Collischonn; Reinaldo Haas; Ivanilto Andreolli; Carlos Eduardo Morelli Tucci

2005-01-01

211

Application of Doppler radar and lidar to diagnose atmospheric phenomena  

Microsoft Academic Search

Observations and comparison of measurements of wind, waves, and turbulence, made with Doppler radar, lidar, and in-situ sensors, are presented. Applications to the detection of weather hazards to safe flight are discussed. A method to estimate rainfall with a polarization diversity Doppler radar is shown to be less sensitive to drop size distribution variations than commonly used Z-R relations. The

R. J. Doviak; M. Eilts; V. Mazur; M. Sachidananda; D. S. Zrnic

1986-01-01

212

Terminal Doppler Weather Radar (TDWR) observation of atmospheric flow over complex terrain during tropical cyclone passages  

NASA Astrophysics Data System (ADS)

To facilitate warning of low-level wind shear associated with convective storms, a Terminal Doppler Weather Radar (TWDR) was installed about 12 km to the northeast of the Hong Kong International Airport (HKIA). The HKIA is located just off the northern shore of an island known as Lantau. The HKIA lies on the lee side of the complex terrain of Lantau when winds come from the east through the southwest. With the commissioning of the TDWR in 1997, interesting high-resolution radar data were collected in strong southerly flows during tropical cyclone passages. These data sets reveal the complex low-level atmospheric flow in the vicinity of the HKIA, including streaks of low-speed flow, reverse flows, small-scale vortices and high-speed gap flows. Animation sequences of the radar images suggest existence of von Karman vortex streets and vortex shedding in the wake regions. These phenomena could induce strong shear regions which led to significant low-level wind shear for landing/departing aircraft. Analysis of on-board flight data for a wind shear event experienced by a landing aircraft in strong southeasterly flow revealed that terrain- induced features with horizontal scale less than 1 km brought significant air speed changes to the aircraft over a short duration of time.

Shun, Chi M.; Lau, Sharon S.

2000-12-01

213

NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds  

NASA Astrophysics Data System (ADS)

The 2006 eruption of Augustine Volcano, Alaska provided an exceptional opportunity to detect and measure explosive volcanic events and to track drifting volcanic clouds using WRS-88D (NEXRAD) weather radar data. Radar data complemented the real-time seismic monitoring by providing rapid confirmation of ash generation and cloud height. The explosive phase of the eruption consisted of thirteen discrete Vulcanian explosions from January 11 to 28, with seismic durations that ranged from one to eleven minutes. The ash columns and drifting clouds from all of the events were observed via a NEXRAD located 185 km NE of the volcano on the Kenai Peninsula (site PAHG). The radar was operated in both precipitation and clear air modes, resulting in a temporal resolution of 4.1 to 10 minutes per complete scan, respectively. Scan elevation angles for the radar beam centroid varied slightly depending upon mode of operation, but values of 0.5, 1.5, 2.5, and 3.5 degrees were typically used, corresponding to altitudes over the volcano of 3.8, 7.2, 10.5, and 13.8 km above sea level. Estimates of eruption cloud height were made by the National Weather Service (NWS) Anchorage Forecast Office using range-height indication cross-sections and radar echo tops (the altitude of the +18.5 dBZ reflectance surface). The observed cloud heights typically ranged from 7.5 to 10.5 km above sea level, with the exception of the January 17 event which briefly had an echo top of about 14 km. Most of the eruption clouds reached their maximum height in the first scan in which they were visible, suggesting an energetic and impulsive initial event, and were at lower heights in subsequent views. These height estimates may be minimum values because very fine-grained ash at the top of eruption clouds has low radar reflectance, and thus may not be observed. Height estimates were rapidly communicated to the NWS Alaska Aviation Weather Unit and the Alaska Volcano Observatory for use in hazard statements and related cloud dispersion modeling. Base reflectivity images at four scan angles provided additional insight into the vertical ash distribution. Generally, the eruption column and associated volcanic clouds had the greatest areal coverage and highest reflectivity values (as high as +60 dBZ) at the two lowest scan elevation angles (0.5 and 1.5 degrees or heights of about 3.8 to 7.2 km above sea level). The explosions on January 13 and 17 produced volcanic clouds that propagated upwind for ten to twenty minutes before dispersing, suggesting that some of the ash was being generated by pyroclastic flows on the flanks. Drifting volcanic clouds were tracked in the data for as long as two hours after the start of the eruption, with reflectivity values as low as -4 dBZ observed. Retrospective analyses of level-3 NEXRAD data from the Kenai (PAHG) and King Salmon (PAKC) radars (200 km SW of Augustine) examined radial base velocity and spectrum width (a measure of the velocity variance within a scan volume) at four scan angles. The highest base velocities observed were for the January 17 event, which reached 33 m/s, the maximum value computed by the level-3 algorithm. This event, and similar ones on January 13, were characterized by moderately high spectrum widths (as large as 9.8 m/s), indicative of turbulence and wind shear.

Schneider, D. J.; Scott, C.; Wood, J.; Hall, T.

2006-12-01

214

A Unified Description of the Statistics of Radar and Gauge Rainfall Data in terms of a Stochastic Dynamical Model  

NASA Astrophysics Data System (ADS)

Rainfall varies in space and time in a highly irregular manner that calls for a probabilistic description. A characteristic feature of rainfall statistics is that they depend strongly on the space-time scales over which rain rate data are averaged. A spectral model of precipitation has been developed based on a linear stochastic dynamical equation for the point rain rate that allows a concise description of the second moment statistics of rain at any prescribed space-time averaging scale. The model is thus capable of providing a unified description of the statistics of both radar and rain gauge data representing rainfall measurement in two distinct regimes — near-instantaneous rain rate spatially averaged over a large area and time-averaged rain rate at a point. The postulated form of the model spectrum gives it adequate flexibility to capture the subtle interplay between the spatial and temporal scales of variability of rain but at the same time strongly constrains the predicted statistical behavior as function of the averaging length and times scales. We test the model by tuning its parameters to fit radar and gauge data (TRMM standard products 2A53 and 2A56) collected contemporaneously at the NASA TRMM ground validation site near Melbourne, Florida.

Kundu, P. K.; Travis, J.

2010-12-01

215

High resolution measurements of aerial rainfall with X-band radars in New Zealand  

Microsoft Academic Search

The Atmospheric Physics Group runs a number of high resolution X-band mobile rain radars. The radars are unusual in that they operate at very high spatial and temporal resolution but short range (100m\\/20sec\\/20km) as compared with the C-band radars of the New Zealand Meteorological Service (2km\\/7min\\/240km). Portability was a key design criterion for the radars, which can either be towed

Luke Sutherland-Stacey; Paul Shucksmith; Geoff Austin

2010-01-01

216

Experiments in Rainfall Estimation with a Polarimetric Radar in a Subtropical Environment  

Microsoft Academic Search

A unique dataset consisting of high-resolution polarimetric radar measurements and dense rain gauge and disdrometer observations collected in east-central Florida during the summer of 1998 was examined. Comparison of the radar measurements and radar parameters computed from the disdrometer observations supported previous studies, which indicate that oscillating drops in the free atmosphere have more spherical apparent shapes in the mean

Edward A. Brandes; Guifu Zhang; J. Vivekanandan

2002-01-01

217

Radar-based Integrated Rainfall Estimates (An extract from Tromel et al., 2008, submitted to Tellus)  

Microsoft Academic Search

Our analysis aim at an enhanced quality of radar derived precipitation estimates by as fully as possible exploiting the information contained in the spatial and temporal variability of the radar signals produced by the complete precipitation generating system, e.g. by a convective cell during its life span. The results presented are yet based on pseudo-radar data and rain rates of

Silke Tromel; Clemens Simmer

218

Prediction of Rainfall from WSR-88D Radar Using Kernel-Based Methods  

Microsoft Academic Search

The main objective of this paper is to utilize standard Support Vector Regression, Least Squares Support Vector Regression, and compare these techniques to traditional regression and a rain rate formula that meteorologists use, to facilitate rainfall estimation and rainfall detection. Ground truth rainfall data are necessary to apply intelligent systems techniques. A unique source of such data is the Oklahoma

Theodore B. Trafalis; Budi Santosa; Michael B. Richman

2003-01-01

219

Application of the Hess-Brezowsky classification to the identification of weather patterns causing heavy winter rainfall in Brittany (France)  

NASA Astrophysics Data System (ADS)

An accurate knowledge of the weather patterns causing winter rainfall over the Scorff watershed in western Brittany (W. France) was developed prior to studies of the impact of the climate factor on land use management, and of the hydrological reponses to rain-producing weather patterns. These two studies are carried out in the context of the climate change. The identification of rainy air-circulation types was realized using the objective computational version of the 29-type Hess and Brezowsky Grosswetterlagen system of classifying European synoptic regimes, for the cold season (November-March) of the 1958-2005 period at the reference weather station of Lorient, and 13 other stations located in western and southern Brittany, including a more detailed study for the wet 2000-2001 cold season for three reference stations of the Scorff watershed (Lorient, Plouay and Plouray). The precipitation proportion (including the days with rainfall ?20 mm) was calculated by major air-circulation type (GWT: see Appendix A) and by individual air-circulation subtype (GWL: see Appendix A) for the studied time-period. The most frequently occurrence of rainy days associated with westerly and southerly GWL confirmed well-known observations in western Europe and so justify the use of the Hess-Brezowsky classification in other areas outside Central Europe. The southern or south-western exposure of the watershed with a hilly inland area enhanced the heavy rainfall generated by the SW and S circulation types, and increased the difference between the rainfall amounts of coastal and inland stations during the wettest days.

Planchon, O.; Quénol, H.; Dupont, N.; Corgne, S.

2009-07-01

220

Hands-On Learning Modules for Interdisciplinary Environments: An Example with a Focus on Weather Radar Applications  

ERIC Educational Resources Information Center

Learning modules provide an effective means of encouraging cognition and active learning. This paper discusses several such modules that have been developed within a course on weather radar applications intended for students from Electrical Engineering and Meteorology. The modules were designed both to promote interdisciplinary exchange between…

Chilson, P. B.; Yeary, M. B.

2012-01-01

221

On-line Monitoring of Weather Radar Antenna Pointing using high-resolution DTM and AI techniques  

Microsoft Academic Search

This paper presents a novel tecnique to continuously monitor the azimuthal pointing accuracy of a weather radar antenna. The technique consists in cross correlating modeled and measured echoes from ground clutter in real-time at low elevation angles in precipitation and non-precipitation conditions. The azimuthal angle with maximum cross- correlation indicates the adjustment in antenna pointing accuracy. The modeled ground clutter

Miguel Rico-Ramirez; Efren Gonzalez-Ramirez; Ian Cluckie

222

Scanning strategies for next generation weather radars. A study based on lifetimes of convective atmospheric phenomena hazardous to aviation  

Microsoft Academic Search

The lifetimes of significant features in typical storm phenomena were investigated and the results are expected to help in deciding the scan strategy of NEXRAD radars. In particular, the question of the adequacy of a 5 minute information update rate for NEXRAD in its aviation weather surveillance role was addressed. Two methods are used for the lifetime study: photo-interpretive and

P. R. Mahapatra; D. S. Zrnic

1982-01-01

223

Hands-On Learning Modules for Interdisciplinary Environments: An Example with a Focus on Weather Radar Applications  

ERIC Educational Resources Information Center

|Learning modules provide an effective means of encouraging cognition and active learning. This paper discusses several such modules that have been developed within a course on weather radar applications intended for students from Electrical Engineering and Meteorology. The modules were designed both to promote interdisciplinary exchange between…

Chilson, P. B.; Yeary, M. B.

2012-01-01

224

A practical example of Moving Target Detection (MTD) processing for an air traffic control radar with weather channel  

Microsoft Academic Search

Air Traffic Control (ATC) radar processing of the Moving Target Detector (MTD) type is described. It comprises an independent processing channel called weather channel, which supplies meteorological data. The MTD processing technique is aimed at improving the detection of useful targets in the midst of clutter. The algorithms employed are detailed, as well as the performance to be expected, in

Christine Bruno

1986-01-01

225

Predicting road hazards caused by rain, freezing rain and wet surfaces and the role of weather radar  

Microsoft Academic Search

Freezing rain in the winter of 1995\\/96 has drawn attention to the severity of black-ice problems on British roads, additional to the normal increased hazards presented to drivers by any form of precipitation. Disruption to traffic was considerable on several days. Weather radar provides improved nowcasting, for both winter and summer conditions, where available real time directly to highway engineers,

Leslie Symons; Allen Perry

1997-01-01

226

Spatial patterns in thunderstorm rainfall events and their coupling with watershed hydrological response 1907  

Technology Transfer Automated Retrieval System (TEKTRAN)

Weather radar systems provide detailed information on spatial rainfall patterns known to play a significant role in runoff generation processes. In the current study, we present an innovative approach to exploit spatial rainfall information of air mass thunderstorms and link it with a watershed hydr...

227

Spatial patterns in thunderstorm rainfall events and their coupling with watershed hydrological response 1894  

Technology Transfer Automated Retrieval System (TEKTRAN)

Weather radar systems provide detailed information on spatial rainfall patterns known to play a significant role in runoff generation processes. In the current study, we present an innovative approach to exploit spatial rainfall of air mass thunderstorms and link it with a watershed hydrological mo...

228

Assimilation of Doppler Radar Observations with a Regional 3DVAR System: Impact of Doppler Velocities on Forecasts of a Heavy Rainfall Case  

Microsoft Academic Search

In this paper, the impact of Doppler radar radial velocity on the prediction of a heavy rainfall event is examined. The three-dimensional variational data assimilation (3DVAR) system for use with the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5) is further developed to enable the assimilation of radial velocity observations. Doppler velocities from the Korean Jindo radar are assimilated into MM5

Qingnong Xiao; Ying-Hwa Kuo; Juanzhen Sun; Wen-Chau Lee; Eunha Lim; Yong-Run Guo; Dale M. Barker

2005-01-01

229

Remote rainfall sensing for landslide hazard analysis  

USGS Publications Warehouse

Methods of assessing landslide hazards and providing warnings are becoming more advanced as remote sensing of rainfall provides more detailed temporal and spatial data on rainfall distribution. Two recent landslide disasters are examined noting the potential for using remotely sensed rainfall data for landslide hazard analysis. For the June 27, 1995, storm in Madison County, Virginia, USA, National Weather Service WSR-88D Doppler radar provided rainfall estimates based on a relation between cloud reflectivity and moisture content on a 1 sq. km. resolution every 6 minutes. Ground-based measurements of rainfall intensity and precipitation total, in addition to landslide timing and distribution, were compared with the radar-derived rainfall data. For the December 14-16, 1999, storm in Vargas State, Venezuela, infrared sensing from the GOES-8 satellite of cloud top temperatures provided the basis for NOAA/NESDIS rainfall estimates on a 16 sq. km. resolution every 30 minutes. These rainfall estimates were also compared with ground-based measurements of rainfall and landslide distribution. In both examples, the remotely sensed data either overestimated or underestimated ground-based values by up to a factor of 2. The factors that influenced the accuracy of rainfall data include spatial registration and map projection, as well as prevailing wind direction, cloud orientation, and topography.

Wieczorek, Gerald F.; McWreath, Harry; Davenport, Clay

2001-01-01

230

The four cumulus cloud modes and their progression during rainfall events: A C-band polarimetric radar perspective  

NASA Astrophysics Data System (ADS)

There is no objective definition to separate cumulus congestus clouds from the shallow cumulus and deep clouds. This has generated misinterpretation about the role of congestus clouds to promote deep convection through the potential of moistening the middle troposphere. In this study, an objective identification for the different tropical cumulus modes is found by examining the occurrence frequency of the cloud cell top heights (CTHs) and near-ground (at 2.5 km height) rainfall properties of these cells using a three-season database of the Darwin C-band polarimetric radar. Four cumulus modes were identified, namely a shallow cumulus mode with CTH in the trade inversion layer (1-3 km), a congestus mode with tops in the highly stable middle troposphere (3-6.5 km), a deep convective mode with tops in the region of free convection (6.5-15 km), and an overshooting convection mode with tops in the tropical tropopause layer (CTH >15 km). The study also investigates the connections between these cumulus modes during heavy rainfall events. The congestus mode occurs predominantly from ~10 h prior to the peak rainfall event to ~2 h past the event. The deep cloud populations (Modes 3 and 4) have their maxima at and shortly after the time of the rainfall peak, with maximum occurrence just below the tropical tropopause layer. A comparison of the heavy rainfall events occurring in morning (oceanic) conditions against the afternoon (continental) conditions revealed a higher ratio of the shallow to the deep cloud population and a shorter transition time from the shallow to the onset of deep population in the morning-oceanic conditions than the afternoon-land conditions. It is also found through the analysis of the large-scale moisture budget data set that for both the morning and afternoon events, the moistening peaked before the peak in the congestus populations.

Kumar, Vickal V.; Jakob, Christian; Protat, Alain; May, Peter T.; Davies, Laura

2013-08-01

231

Correcting the radar rainfall forcing of a hydrological model with data assimilation: application to flood forecasting in the Lez catchment in Southern France  

NASA Astrophysics Data System (ADS)

The present study explores the application of a data assimilation (DA) procedure to correct the radar rainfall inputs of an event-based, distributed, parsimonious hydrological model. An extended Kalman filter algorithm was built on top of a rainfall-runoff model in order to assimilate discharge observations at the catchment outlet. This work focuses primarily on the uncertainty in the rainfall data and considers this as the principal source of error in the simulated discharges, neglecting simplifications in the hydrological model structure and poor knowledge of catchment physics. The study site is the 114 km2 Lez catchment near Montpellier, France. This catchment is subject to heavy orographic rainfall and characterised by a karstic geology, leading to flash flooding events. The hydrological model uses a derived version of the SCS method, combined with a Lag and Route transfer function. Because the radar rainfall input to the model depends on geographical features and cloud structures, it is particularly uncertain and results in significant errors in the simulated discharges. This study seeks to demonstrate that a simple DA algorithm is capable of rendering radar rainfall suitable for hydrological forecasting. To test this hypothesis, the DA analysis was applied to estimate a constant hyetograph correction to each of 19 flood events. The analysis was carried in two different modes: by assimilating observations at all available time steps, referred to here as reanalysis mode, and by using only observations up to 3 h before the flood peak to mimic an operational environment, referred to as pseudo-forecast mode. In reanalysis mode, the resulting correction of the radar rainfall data was then compared to the mean field bias (MFB), a corrective coefficient determined using rain gauge measurements. It was shown that the radar rainfall corrected using DA leads to improved discharge simulations and Nash-Sutcliffe efficiency criteria compared to the MFB correction. In pseudo-forecast mode, the reduction of the uncertainty in the rainfall data leads to a reduction of the error in the simulated discharge, but uncertainty from the model parameterisation diminishes data assimilation efficiency. While the DA algorithm used is this study is effective in correcting uncertain radar rainfall, model uncertainty remains an important challenge for flood forecasting within the Lez catchment.

Harader, E.; Borrell-Estupina, V.; Ricci, S.; Coustau, M.; Thual, O.; Piacentini, A.; Bouvier, C.

2012-11-01

232

An examination of the effect of wind-drift on radar-derived surface rainfall estimations  

Microsoft Academic Search

The error in location caused by the non-vertical fall of precipitation from the height at which it was observed by radar to the surface has long been remarked upon, but rarely examined. The study described in this paper uses wind fields determined using Doppler radar to estimate the trajectories of falling drops and thereby assess the error induced in surface

Steven A. Lack; Neil I. Fox

2007-01-01

233

Comparison of TRMM precipitation radar and microwave imager rainfall retrievals in tropical cyclone inner cores and rainbands  

NASA Astrophysics Data System (ADS)

Tropical Rainfall Measuring Mission (TRMM) rainfall retrieval algorithms are evaluated in tropical cyclone (TC) inner cores (IC), inner bands (IB), and outer rainbands (OB). In total, 1329 IC, 2149 IB, and 4627 OB storm regions are analyzed using data from a 12-year TRMM Tropical Cyclone Precipitation Feature (TCPF) database containing 1013 TCs viewed from December 1997 to December 2009. Attention is focused on the difference between the Precipitation Radar (PR) 2A25 and the TRMM Microwave Imager (TMI) 2A12 rainfall algorithms. The PR 2A25 produces larger mean rain rates than the TMI 2A12 in inner cores and inner bands, with the greatest difference occurring in hurricanes. This discrepancy is caused mostly by the TMI 2A12 significantly underestimating regions of moderate to heavy rain >15 mm hour-1 or when the PR reflectivity is greater than 30 dBZ. The TMI 2A12 rain rates are most closely related to the percentage coverage of 85 GHz polarization-corrected brightness temperature (PCT) <225 K in the IC and 85 GHz PCT <250 K in the IB and OB. These convective parameters are good predictors of the mean TMI 2A12 rain rate, but significant ice scattering is not always present in areas of heavy rain that are often widespread in TC inner regions. As a result, the TMI 2A12 algorithm may poorly measure the rain rate, particularly in the inner core of hurricanes.

Zagrodnik, Joseph P.; Jiang, Haiyan

2013-01-01

234

Rainfall stochastic modeling for runoff forecasting  

NASA Astrophysics Data System (ADS)

Rainfall fields estimation over a catchment area is an important stage in many hydrological applications. In this context, weather radars have several advantages because a single-site can scan a vast area with very high temporal and spatial resolution. The construction of weather radar systems with dual polarization capability allowed progress on radar rainfall estimation and its hydro-meteorological applications. For these applications of radar data it is necessary to remove the ground clutter contamination with an algorithm based on the backscattering signal variance of the differential reflectivity. The calibration of the GDSTM model (Gaussian Displacements Spatial Temporal Model), a cluster stochastic generation model in continuous space and time, is herewith presented. In this model, storms arrive in a Poisson process in time with cells occurring in each storm that cluster in space and time. The model is calibrated, using data collected by the weather radar Polar 55C located in Rome, inside a square area of 132 × 132 km2, with the radar at the centre. The GDSTM is fitted to sequences of radar images with a time interval between the PPIs scans of 5 min. A generalized method of moment procedure is used for parameter estimation. For the validation of the ability of the model to reproduce internal structure of rain event, a geo-morphological rainfall-runoff model, based on width function (WFIUH), was calibrated using simulated and observed data. Several rainfall fields are generated with the stochastic model and later they are used as input of the WFIUH model so that the forecast discharges can be compared to the observed ones.

Russo, Fabio; Lombardo, Federico; Napolitano, Francesco; Gorgucci, Eugenio

235

Weather  

NSDL National Science Digital Library

Learn all about the aspects of weather that effect us every day. Click here to see a weather forecast for anywhere in the world World Wide Weather Watch See what happens to weather when you change conditions at your house Weather Maker Weather Games ...

Hyde, Mrs.

2007-02-08

236

Weather  

NSDL National Science Digital Library

This lesson is written for fourth grade students. Students will explore weather and the effects it has on their lives. What is weather? video of what is weather Let's take a walk through the weather. Put on your hats and coats! Clouds Cloud Types Clouds - Dan's Wild Weather Page What to Wear? What to Wear? What to Drink? Weather Patterns and Climatic Regions ...

Bullough, Ms.

2010-06-24

237

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

238

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

239

Implications of radar rainfall estimates uncertainty on distributed hydrological model predictions  

NASA Astrophysics Data System (ADS)

Real time availability and high space-time resolution of radar based quantitative precipitation estimates (QPE) are appealing features for spatially detailed hydrological prediction and forecasting applications using distributed hydrological models. However, the data obtained remain an important source of uncertainty for hydrological predictions. Insight into the characteristics of this uncertainty is still limited and its quantification is a challenging task. This work studies the characteristics of radar QPE uncertainties and its implications on both hydrological modelling results and hydrological model parameter estimates. The uncertainty of a real time radar QPE product available in 10 minute intervals on a 1 km 2 grid is quantified by comparison to a reference precipitation field, which includes additional observations from rain gauge records. Based on this analysis a probabilistic model is proposed that describes the uncertainty structure of the radar QPE field. An ensemble of precipitation fields is generated that represents a quantitative estimate of radar QPE uncertainty from the sampling of the probabilistic model. On this basis the implications of radar QPE uncertainty on distributed hydrological model predictions are studied. The methodology proposed is applied to a real-world case study using the river basin of the Besòs in Spain as a test bed. The feasibility of the approach to condense the knowledge about radar QPE uncertainty in a probabilistic model and to map this uncertainty to the response of a hydrological model using an ensemble of precipitation fields is demonstrated. The results show that the probabilistic use of radar QPE may add valuable information to hydrological predictions and may reduce the bias of hydrological model parameter estimates.

Schröter, Kai; Llort, Xavier; Velasco-Forero, Carlos; Ostrowski, Manfred; Sempere-Torres, Daniel

2011-05-01

240

Attenuation correction for a high-resolution polarimetric X-band weather radar  

NASA Astrophysics Data System (ADS)

In 2007, IRCTR (Delft University of Technology) installed a new polarimetric X-band LFMCW radar (IDRA) at the meteorological observation site of Cabauw, The Netherlands. It provides plan position indicators (PPI) at a fixed elevation with a high range resolution of either 3 m or 30 m at a maximum observation range of 1.5 km and 15 km, respectively. IDRA aims to monitor precipitation events for the long-term analysis of the hydrological cycle. Due to the specifications of IDRA, the spatial and temporal variability of a large range of rainfall intensities (from drizzle to heavy convective rain) can be studied. Even though the usual observation range of IDRA is limited to 15 km, attenuation due to precipitation can be large enough to seriously affect the measurements. In this contribution we evaluate the application of a combined method to correct for the specific and the differential attenuation, and in the same vein estimate the parameters of the raindrop-size distribution. The estimated attenuations are compared to a phase constraint attenuation correction method.

Otto, T.; Russchenberg, H. W. J.

2010-11-01

241

The potential for hail and intense rainfall enhancement over urban areas: improving urban extreme weather risk assessment  

NASA Astrophysics Data System (ADS)

Urban communities and their infrastructure are particularly vulnerable to the impacts of organized thunderstorm systems. Current models of urban extreme weather risk do not fully represent the complexity of the hydrometeorological processes involved, particularly in relation to intense convective precipitation and severe weather. Hail is a severe thunderstorm hazard that can be extremely damaging to property (especially automobiles, buildings and agriculture) over and in proximity to urban environments. This study identifies some of the mechanisms that future generations of catastrophe models should consider incorporating in their representation of hydrometeorlogical hazards in urban areas. In addition, such information could help to inform planning policy and improve urban resilience to extreme events. Evidence is provided that urban environments, through the existence of high-rise buildings and densely build-up areas, but also through air-pollution (aerosols) can potentially lead to an enhancement of both flooding and hail. Conclusions are drawn from two separate studies over the heavily urbanized corridor of the northeastern United States but could be expanded to apply to other urban areas. Observational and modelling (Weather Research and Forecasting - WRF) analyses of an extreme thunderstorm over the Baltimore, Maryland metropolitan area on 7 July 2004 provided evidence that the urban canopy redistributed heavy rainfall and convergence centres in the vicinity of the urban environment. Modelling analyses suggest that convective rainfall around the urban core was increased by about 30% due to the heterogeneities of land surface processes associated with the city of Baltimore. Chesapeake Bay also played an important role in rainfall distribution by acting as a divergence zone for northerly winds. Cloud-to-ground lightning analyses show that the city of Baltimore and the Chesapeake Bay combined played a role in the distribution of lightning in the periphery of the urban core. Detailed modelling analyses (WRF-Chem) of a series of convective storms over the New York City metropolitan area, suggest that under certain meteorological conditions, increased concentrations of aerosols can lead to better organization of convection, higher vertical velocities and significantly increased convective rainfall accumulations. Higher vertical velocities were more widespread and reached deeper atmospheric levels when meteorological conditions were favourable, under increased aerosol concentrations. Areas that are downstream of sources of aerosols (i.e. New York City) are more prone to experience convective enhancement.

Ntelekos, A. A.; Smith, J. A.; Krajewski, W. F.; Foote, M.

2009-04-01

242

Validation of attenuation, beam blockage, and calibration estimation methods using two dual polarization X band weather radars  

NASA Astrophysics Data System (ADS)

The amplitude a of radar wave reflected by meteorological targets can be misjudged due to several factors. At X band wavelength, attenuation of the radar beam by hydro meteors reduces the signal strength enough to be a significant source of error for quantitative precipitation estimation. Depending on the surrounding orography, the radar beam may be partially blocked when scanning at low elevation angles, and the knowledge of the exact amount of signal loss through beam blockage becomes necessary. The phase shift between the radar signals at horizontal and vertical polarizations is affected by the hydrometeors that the beam travels through, but remains unaffected by variations in signal strength. This has allowed for several ways of compensating for the attenuation of the signal, and for consistency checks between these variables. In this study, we make use of several weather radars and gauge network measuring in the same area to examine the effectiveness of several methods of attenuation and beam blockage corrections. The methods include consistency checks of radar reflectivity and specific differential phase, calculation of beam blockage using a topography map, estimating attenuation using differential propagation phase, and the ZPHI method proposed by Testud et al. in 2000. Results show the high effectiveness of differential phase in estimating attenuation, and potential of the ZPHI method to compensate attenuation, beam blockage, and calibration errors.

Diederich, M.; Ryzhkov, A.; Simmer, C.; Mühlbauer, K.

2011-12-01

243

The application of high latitude ionosphere radars for space weather research  

Microsoft Academic Search

Ionospheric radars are used to investigate the auroral and polar cap regions, where solar wind-magnetosphere-ionosphere coupling is most evident. There are basically four categories of ground-based radars applied for this purpose: The digital ionosondes, coherent backscatter HF radars (F-region), coherent backscatter VHF and UHF radars (E-region), and incoherent scatter VHF and UHF radars. These systems are briefly described and examples

J. Röttger

2002-01-01

244

Terminal Doppler Weather Radar (TDWR) Build 5B Operational Test and Evaluation (OT E) Integration and OT E Operational Test Plan.  

National Technical Information Service (NTIS)

The Terminal Doppler Weather Radar (TDWR) Build 5B Enhancement Operational Test and Evaluation (OTE) Integration and OTE Operational Test Plan provides the overall philosophy and approach to Build 5B OTE testing, and identifies OTE objectives, responsibil...

R. Martinez S. Viveiros D. Wedge P. Guthlein

1995-01-01

245

Terminal Doppler Weather Radar (TDWR) Low Level Wind Shear Alert System 3 (LLWAS 3) Integration Studies at Orlando International Airport in 1991 and 1992.  

National Technical Information Service (NTIS)

In 1993 the Federal Aviation Administration (FAA) began deploying two new wind shear detection systems: the Terminal Doppler Weather Radar (TDWR) and the third-generation Low Level Windshear Alert System (LLWAS 3). Currently, 9 airports are scheduled to r...

R. E. Cole R. F. Todd

1994-01-01

246

Calibration of radars using polarimetric techniques  

Microsoft Academic Search

A method that uses the properties of rain medium itself to obtain accurate weather radar system gain calibration is discussed. This technique is based on the principle that the rainfall rate measured using absolute reflectivity (Z) and differential reflectivity ( ZDR) is the same as that obtained from specific differential phase (KDP). The measurements required for this technique are Z,

Eugenio Gorgucci; Gianfranco Scarchilli; V. Chandrasekar

1992-01-01

247

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part II: Range–Velocity Ambiguity Mitigation  

Microsoft Academic Search

Multiple pulse-repetition interval (multi-PRI) transmission is part of an adaptive signal transmission and processing algorithm being developed to combat range-velocity (RV) ambiguity for the Terminal Doppler Weather Radar (TDWR). In Part I of this two-part paper, an adaptive clutter filtering procedure that yields low biases in the moments estimates was presented. In this part, algorithms for simultaneously providing range-overlay protection

John Y. N. Cho

2005-01-01

248

Assimilating spaceborne radar and ground-based weather station data for operational snow-covered area estimation  

Microsoft Academic Search

An enhanced method for snow-covered area (SCA) estimation for boreal forest zone is presented. The method combines TKK developed spaceborne radar-based SCA estimation with ground-based weather station observations. The purpose is to improve the reliability of SCA estimates near and after the end of snow-melt season. The SCA estimates acquired with the enhanced method are compared with optical satellite data-based

K. Luojus; J. Pulliainen; S. Metsamaki; S. Anttila; M. Hallikainen

2007-01-01

249

The Gust Front Detection Algorithm For The Terminal Doppler Weather Radar: Impact Of Nexrad Scan Strategies; Detecting Non-gust Front Phenomena  

Microsoft Academic Search

The procedures used by the Terminal Doppler Weather Radar (TDWR) gust front algorithm (GFA) to detect gust fronts are briefly reviewed. Two potential applications of the GFA are then discussed. First, the results of a study that was completed to determine if the GFA could be placed on a Next Generation Radar (NEXRAD) system are discussed. Second, the capability of

Gregory J. Stumpf

1990-01-01

250

The effectiveness of adaptive PRF (Pulse Repetition Frequency) selection in minimizing range obscuration in the TDWR (Terminal Doppler Weather Radar) system  

Microsoft Academic Search

An adaptive procedure for selecting radar pulse repetition frequency (PRF) has been developed as the primary means of minimizing the occurrence of range aliased echoes within operationally significant coverage areas (e.g., airport runways) of the Terminal Doppler Weather Radar (TDWR) system. This procedure underwent extensive testing at the S-Band TDWR testbed while located in Denver, CO, where it was judged

S. C. Crocker

1989-01-01

251

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

252

Terminal Doppler Weather Radar Observation of Atmospheric Flow over Complex Terrain during Tropical Cyclone Passages.  

NASA Astrophysics Data System (ADS)

A Terminal Doppler Weather Radar (TDWR) started operation in Hong Kong, China, in 1997 for monitoring wind shear associated with thunderstorms affecting the Hong Kong International Airport. The airport was built on land reclaimed from the sea and lies to the immediate north of the mountainous Lantau Island, which has hills rising to nearly 1000 m. Since 1997, the airport experienced a number of tropical cyclone passages, some bringing strong southerly winds across these hills. Under these conditions the TDWR captured interesting but complex flow patterns in the lower atmosphere. The TDWR Doppler velocity datasets reveal features not previously observed with conventional instruments. These include shear lines, reverse flow, small-scale vortices, streaks of low-speed flow set against a high-speed background, as well as gap-related downslope high-speed flow. Hovmöller diagrams constructed from the Doppler velocity data bring out in considerable detail periodic shedding of vortices and transient wind patterns in the wake of the hills.

Shun, C. M.; Lau, S. Y.; Lee, O. S. M.

2003-12-01

253

Weather  

NSDL National Science Digital Library

Meteorologists study the weather by recording and analyzing data. You can become an amateur meteorologist by building your own weather station and keeping a record of your measurements. After a while, you\\'ll notice the weather patterns that allow meteorologists to forecast the weather. Tasks: 1. As a group you will build a weather station outside. 2. Your group will build instruments to measure the weather. 3. Each person will record the data in personal weather journals. Process: 1.Since weather happens outside, you\\'ll need to make ...

Tuttle, Rachelle

2005-10-25

254

A Probable Unexplored Meteorite Fall Found in Archived Weather Radar Data  

NASA Astrophysics Data System (ADS)

Imagery from NEXRAD radar archives appears to show a meteorite fall at a location defined by eyewitness accounts of a bright meteor event just north of Jacksonville, Illinois, on 04 Feb 2007. Archived radar data may contain many undiscovered falls.

Fries, M.; Fries, J.; Schaefer, J.

2011-03-01

255

Two weather radar time series of the altitude of the volcanic plume during the May 2011 eruption of Grímsvötn, Iceland  

NASA Astrophysics Data System (ADS)

The eruption of Grímsvötn volcano in Iceland in 2011 lasted for a week, 21-28 May. The eruption was explosive and peaked during the first hours, with the eruption plume reaching 20-25 km altitude. The height of the plume was monitored every 5 min with a C-band weather radar located at Keflavík International Airport and a mobile X-band radar, 257 km and 75 km distance from the volcano respectively. In addition, photographs taken during the first half-hour of the eruption give information regarding the initial rise. Time series of the plume-top altitude were constructed from the radar observations. This paper presents the two independent radar time series. The series have been cross validated and there is a good agreement between them. The echo top radar series of the altitude of the volcanic plume are publicly available from the Pangaea Data Publisher (doi:10.1594/PANGAEA.778390).

Petersen, G. N.; Bjornsson, H.; Arason, P.; von Löwis, S.

2012-10-01

256

Two weather radar time series of the altitude of the volcanic plume during the May 2011 eruption of Grímsvötn, Iceland  

NASA Astrophysics Data System (ADS)

The eruption of Grímsvötn volcano in Iceland in 2011 lasted for a week, 21-28 May. The eruption was explosive and peaked during the first hours, with the eruption plume reaching 20-25 km altitude. The height of the plume was monitored every 5 min with a C-band weather radar located at Keflavík International Airport and a mobile X-band radar, 257 km and 75 km distance from the volcano, respectively. In addition, photographs taken during the first half-hour of the eruption give information regarding the initial rise. Time series of the plume-top altitude were constructed from the radar observations. This paper presents the two independent radar time series. The series have been cross validated and there is a good agreement between the time series. The echo top radar series of the altitude of the volcanic plume are publicly available from the Pangaea Data Publisher (http://doi.pangaea.de/10.1594/PANGAEA.778390).

Petersen, G. N.; Bjornsson, H.; Arason, P.; von Löwis, S.

2012-05-01

257

Radar analysis of cloud systems and their rainfall yield in Israel  

Microsoft Academic Search

Abstract This study documents,the climatological occurrence of rainfall contributed from different types of rain cloud systems over Israel and the adjacent sea. The rainy cloud types are: a. Cold front. b. Cloud systems that develop in the cold sector of the cyclones. c. Cloudiness of the cyclone center (vortex). The cloud systems within the cold sector include: a. Convection lines.

Yair Goldreich; Hanan Mozes; Daniel Rosenfeld

2004-01-01

258

Analysis of Surface and Radar Rainfall Observations during Two Tropical Systems in South Louisiana  

Microsoft Academic Search

This study presents comparative analyses on rainfall observations made during two tropical systems that affected south Louisiana: tropical storm Matthew in October 2004, and Hurricane Rita in September 2005. Storm Matthew formed from a tropical wave in the southwestern Gulf of Mexico on October 6th and made landfall on south Louisiana on October 10th causing as much as 10 inches

E. Habib; A. Tokay; E. Meselhe; C. Malakpet

2006-01-01

259

A distributed model for slope stability analysis using radar detected rainfall intensity  

Microsoft Academic Search

The term shallow landslides is widely used in literature to describe a slope movement of limited size that mainly develops in soils up to a maximum of a few meters. Shallow landslides are usually triggered by heavy rainfall because, as the water starts to infiltrate in the soil, the pore-water pressure increases so that the shear strength of the soil

L. Leoni; G. Rossi; F. Catani

2009-01-01

260

Extracting bird migration information from C-band Doppler weather radars  

Microsoft Academic Search

Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since the early 1990s, Doppler radars and wind profilers have been introduced in

Gasteren van J. R; IWAN HOLLEMAN; WILLEM BOUTEN; EMIEL VAN LOON; J. Z. Shamoun Baranes

2008-01-01

261

Development of an Off-The-Grid X-band radar for weather applications  

Microsoft Academic Search

The Student Led Test Bed (STB) is part of the NSF Engineering Research Center CASA and is currently focused in developing low-cost and low infrastructure radar networks to fill lower atmosphere gaps not covered by current technology. The first radar node, which is part of a small region radar network, will significantly improve the time and spatial resolution of the

Gianni Alexis Pablos-Vega; Jose G. Colom-Ustariz; Sandra Cruz-Pol; Jorge M. Trabal; V. Chandrasekar; Jim George; Francesc Junyent

2010-01-01

262

A mobile X-POL weather radar for hydrometeorological applications in the metropolitan area of São Paulo, Brazil  

NASA Astrophysics Data System (ADS)

This paper presents the first mobile X-band dual-polarization Doppler weather radar termed MXPOL operated by the Laboratory of Hydrometeorology (LABHIDRO) of the University of São Paulo, São Paulo, Brazil. It is used in graduate and under graduate courses, real time monitoring and nowcasting of severe weather in the Metropolitan Area of São Paulo (MASP). It is one of the first of its kind to be used operationally to provide real time high spatial resolution polarimetric data. MXPOL is an important component of a Hydrometeorological Forecast System (Pereira Filho et al., 2005) for MASP. This manuscript presents some instances of MXPOL polarimetric measurements of weather systems and their respective microphysical, dynamical and boundary layer features that can improve nowcasting.

Pereira Filho, A. J.

2012-05-01

263

A mobile X-POL weather radar for hydrometeorological applications in the metropolitan area of São Paulo, Brazil  

NASA Astrophysics Data System (ADS)

This paper presents the first mobile X-band dual-polarization Doppler weather radar termed MXPOL operated by the Laboratory of Hydrometeorology (LABHIDRO) of the University of São Paulo, São Paulo, Brazil. It is used in graduate and under graduate courses, real-time monitoring and nowcasting of severe weather in the Metropolitan Area of São Paulo (MASP). It is one of the first of its kind to be used operationally to provide real-time high spatial resolution polarimetric data. MXPOL is an important component of a Hydrometeorological Forecast System (Pereira Filho et al., 2005) for MASP. This manuscript presents some instances of MXPOL polarimetric measurements of weather systems and their respective microphysical, dynamical and boundary layer features that can improve nowcasting.

Pereira Filho, A. J.

2012-11-01

264

Weather.  

ERIC Educational Resources Information Center

|This theme issue of "The Goldfinch" focuses on weather in Iowa and weather lore. The bulletin contains historical articles, fiction, activities, and maps. The table of contents lists: (1) "Wild Rosie's Map"; (2) "History Mystery"; (3) "Iowa's Weather History"; (4) "Weather Wonders"; (6) "Seasonal Jobs"; (7) "Fiction: Winter Courage"; (8) "Stayin'…

Ruth, Amy, Ed.

1996-01-01

265

High-Resolution Rainfall Rate and DSD Estimation From X-Band Polarimetric Radar Measurements  

NASA Astrophysics Data System (ADS)

This study describes newly developed attenuation correction and microphysical retrieval methods for X-band polarimetric radar (XPOL). It concentrates on exploring the dependence of the retrieval on raindrop size distribution variability, and its sensitivity with respect to the selection of oblateness-size relation (or axial ratio) and maximum diameter limit. Variations in the assumed form of the raindrop axial ratio may result in significant biases in attenuation and microphysical retrievals. In addition, at this wavelength, resonance occurs for sizes larger than about 4 mm, and therefore several polarimetric variables exhibit non-monotone dependence on the drop diameter. An algorithm is developed and experimentally validated for retrieving DSD model parameters. The DSD model is assumed to be a three-parameter "normalized" gamma distribution. Simultaneous and closely matched radar rays from non-attenuated (S-band) dual-polarization radar measurements and corresponding DSD retrievals are used to validate the proposed XPOL algorithm in terms of attenuation correction, as well as DSD parameter retrievals.

Anagnostou, M.; Anagnostou, E.; Vivekanandan, J.

2004-05-01

266

Comparison of TRMM precipitation radar with NEXRAD and in-situ rain gauges in central and south Florida  

Microsoft Academic Search

The purpose of this paper is to use various mathematical methods for processing precipitation data and presenting an independent ground-based measurement of rainfall rate and accumulation for calibration of TRMM Precipitation Radar (PR). Reflectivity data from the Melbourne National Weather Service WSR-88D Next generation Radar (NEXRAD) were collocated in time and space with gauge data located in Central and South

Qinghua Han; Chris Eubanks; W. Linwood Jones; Takis Kasparis

2000-01-01

267

A Mediterranean nocturnal heavy rainfall and tornadic event. Part I: Overview, damage survey and radar analysis  

Microsoft Academic Search

This study presents an analysis of a severe weather case that took place during the early morning of the 2nd of November 2008, when intense convective activity associated with a rapidly evolving low pressure system affected the southern coast of Catalonia (NE Spain). The synoptic framework was dominated by an upper level trough and an associated cold front extending from

Joan Bech; Nicolau Pineda; Tomeu Rigo; Montserrat Aran; Jéssica Amaro; Miquel Gayà; Joan Arús; Joan Montanyà; Oscar van der Velde

2011-01-01

268

Accessibility and Utilization of WSR-88D Radar Precipitation Data for Natural Resource Modeling Applications  

Microsoft Academic Search

The National Weather Service (NWS) operates approximately 160 WSR-88D radar-precipitation stations as part of a Next Generation Radar (NEXRAD) program that began implementation in 1992. Among other products, these radar sites provide spatial rainfall estimates, at approximately 4 km2 resolution (Stage 1, Level 3 data), with nominal coverage of 96% of the coterminous United States. Effective coverage is much less

S. P. Hardegree

2001-01-01

269

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.

270

By Air and Land: Estimating Post-Fire Debris-Flow Susceptibility through High-Resolution Radar Reflectivity and Tipping-Bucket Gage Rainfall  

NASA Astrophysics Data System (ADS)

Wildfires often increase the occurrence of post-fire hazardous flash floods and debris flows from steeplands during intense rainfall. Rainfall intensity-duration thresholds have been used to forecast when this hazard increases rapidly; one threshold for Southern California is 15 mm/hr. However, such thresholds are usually developed with point measurements that only capture a small portion of the landscape. In an attempt to limit potential loss of life, the USGS is collaborating with NOAA on a demonstration early-warning system. To address the lack of spatial rainfall coverage, NOAA deployed a small mobile radar truck (SMART-R) to the Day fire in the western Transverse Range during the 2006-07 winter, and to the Canyon and Corral fires in the Santa Monica Mountains near Malibu during the 2007-08 winter. The SMART-R's C-band Doppler radar can be used to estimate rainfall rates over entire burned areas. On topography susceptible to debris flows within these 3 fires, the USGS installed a dense array of ground-based instruments, including 8 tipping- bucket rain gages in the Day fire, and 3 each in the Canyon and Corral fires. After converting hourly time- step grids of SMART-R reflectivity (150 m node spacing) into precipitation estimates, we compared the gage data to its spatially coincident SMART-R cell.Results from the Day fire indicate that SMART-R derived seasonal and event-based rainfall totals were typically greater than gage totals during the 2006-07 winter of record-low rainfall. Both data sets, however, reflected similar spatial patterns of rainfall intensity. In contrast, for the Malibu fires there is no systematic agreement in spatial pattern or rainfall mismatch; the difference between the two data sets. Of the 9 storms recorded during this 2007-08 winter, SMART-R estimates of rainfall totals exceeded the gage totals for only 3, underestimating totals for the remaining 6. The mismatch magnitudes also exceed that of the previous winter recorded at the Day fire, and, for the largest storm of the season, was 129 mm less than a rain gage total.These discrepancies reduce the reliability of a potential SMART-R-advised warning system, assuming truth from ground-based gages. During the 2007-08 winter near Malibu the rain gages recorded that the 15 mm/hr warning threshold was exceeded during only one storm, and only at one gage in the Corral fire. This event transported large amounts of sediment that resulted in road closures, and it produced at least one "firehose" debris flow generated by runoff from steep, exposed bedrock. In contrast, SMART-R derived rainfall intensities exceeded this threshold at all gage locations for 2 of the 3 storms with overestimated rainfall intensities. It underestimated rainfall intensities for the 6 remaining storms; such underestimates could have led to potential false negatives, which are of concern for preserving human life.It is not yet clear which storms are amenable to the use of SMART-R technology for capturing spatial estimates of rainfall intensity, but results from the Day fire showing topographically forced rainfall patterns support validity of the system. Future work needs to address discrepancies arising from comparing spatially continuous atmospheric radar measurements with terrestrial point measurements. One effort to mitigate some interpretation complexities could include the installation of a disdrometer along with the rain gages, to measure rain drop-size distributions to calibrate in near real-time the relation between measured reflectivity and inferred rainfall.

Hanshaw, M. N.; Schmidt, K. M.; Jorgensen, D. P.; Stock, J. D.

2008-12-01

271

Satellite and Radar Analysis of Mesoscale Weather Systems in the Tropics.  

National Technical Information Service (NTIS)

Gridded Miami WSR-57 radar PPI data during the summer of 1968 are used to study the coverages and frequencies of radar echoes typically associated with five convective regimes in South Florida. Three sets of maps are presented showing the average coverage...

H. P. Gerrish

1972-01-01

272

Weather radar polarimetry: path integrated differential phase shift optimum polarization and the elliptical EF-basis  

Microsoft Academic Search

Polarimetric pulsed Doppler radar measurements of meteorological targets yield mean backscattering properties of hydrometeors in the considered range cells and provide information on propagation effects along the radar ray of propagation. In this paper, two aspects of choosing an optimum polarimetric measurement basis are examined. First, the polarization dependence of path integrated differential phase shift is studied starting from the

V. Ziegler; E. Lüneburg; A. Schroth

1995-01-01

273

Radar data assimilation for the simulation of mesoscale convective systems  

NASA Astrophysics Data System (ADS)

A heavy rainfall case related to Mesoscale Convective Systems (MCSs) over the Korean Peninsula was selected to investigate the impact of radar data assimilation on a heavy rainfall forecast. The Weather Research and Forecasting (WRF) three-dimensional variational (3DVAR) data assimilation system with tuning of the length scale of the background error covariance and observation error parameters was used to assimilate radar radial velocity and reflectivity data. The radar data used in the assimilation experiments were preprocessed using quality-control procedures and interpolated/thinned into Cartesian coordinates by the SPRINT/CEDRIC packages. Sensitivity experiments were carried out in order to determine the optimal values of the assimilation window length and the update frequency used for the rapid update cycle and incremental analysis update experiments. The assimilation of radar data has a positive influence on the heavy rainfall forecast. Quantitative features of the heavy rainfall case, such as the maximum rainfall amount and Root Mean Squared Differences (RMSDs) of zonal/meridional wind components, were improved by tuning of the length scale and observation error parameters. Qualitative features of the case, such as the maximum rainfall position and time series of hourly rainfall, were enhanced by an incremental analysis update technique. The positive effects of the radar data assimilation and the tuning of the length scale and observation error parameters were clearly shown by the 3DVAR increment.

Lee, Jo-Han; Lee, Hyun-Ha; Choi, Yonghan; Kim, Hyung-Woo; Lee, Dong-Kyou

2010-09-01

274

A GIS-based methodology for the assessment of weather radar beam blockage in mountainous regions: two examples from the US NEXRAD network  

NASA Astrophysics Data System (ADS)

The US National Weather Service (NWS) has installed a large network of weather Surveillance radars (WSR-88D) that provide precipitation maps for the United States. Many of these radars operate in mountainous regions and consequently suffer from beam blockage caused by terrain obstacles. The authors present a methodology for assessing the severity of the beam blockage and outline its implications for radar-derived precipitation estimates. The methodology involves the calculation of two-dimensional maps of power loss using a digital elevation model (DEM)-based algorithm of beam propagation for different radar antenna elevation angles. Using a large sample of actual radar data, the authors compare the simulated beam blockage results with the probability of detection of radar reflectivity above a certain threshold. The authors also compare their results with similar but coarser resolution blockage maps developed by the NWS and used in the NEXRAD system. For visualization, ArcGIS software is used to illustrate the results and offer a physical interpretation of the analyses. The study involves two NEXRAD sites: KRLX in Charleston, West Virginia and KEMX in Tucson, Arizona. The KRLX site does not suffer from significant blockage except for a single narrow sector. By contrast, the KEMX site contains several areas of blockage. The authors conclude that DEM-based prediction of radar beam occultation is a viable tool, as indicated by the good agreement of the calculated patterns of power loss with the actual long-term radar data.

Krajewski, Witold F.; Ntelekos, Alexandros A.; Goska, Rados?aw

2006-04-01

275

High-Resolution Rainfall From Radar Reflectivity and Terrestrial Rain Gages for use in Estimating Debris-Flow Susceptibility in the Day Fire, California  

NASA Astrophysics Data System (ADS)

Constraining the distribution of rainfall is essential to evaluating the post-fire mass-wasting response of steep soil-mantled landscapes. As part of a pilot early-warning project for flash floods and debris flows, NOAA deployed a portable truck-mounted Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) to the 2006 Day fire in the Transverse Ranges of Southern California. In conjunction with a dense array of ground- based instruments, including 8 tipping-bucket rain gages located within an area of 170 km2, this C-band mobile Doppler radar provided 200-m grid cell estimates of precipitation data at fine temporal and spatial scales in burned steeplands at risk from hazardous flash floods and debris flows. To assess the utility of using this data in process models for flood and debris flow initiation, we converted grids of radar reflectivity to hourly time-steps of precipitation using an empirical relationship for convective storms, sampling the radar data at the locations of each rain gage as determined by GPS. The SMART-R was located 14 km from the farthest rain gage, but <10 km away from our intensive research area, where 5 gages are located within <1-2 km of each other. Analyses of the nine storms imaged by radar throughout the 2006/2007 winter produced similar cumulative rainfall totals between the gages and their SMART-R grid location over the entire season which correlate well on the high side, with gages recording the most precipitation agreeing to within 11% of the SMART-R. In contrast, on the low rainfall side, totals between the two recording systems are more variable, with a 62% variance between the minimums. In addition, at the scale of individual storms, a correlation between ground-based rainfall measurements and radar-based rainfall estimates is less evident, with storm totals between the gages and the SMART-R varying between 7 and 88%, a possible result of these being relatively small, fast-moving storms in an unusually dry winter. The SMART-R also recorded higher seasonal cumulative rainfall than the terrestrial gages, perhaps indicating that not all precipitation reached the ground. For one storm in particular, time-lapse photographs of the ground document snow. This could explain, in part, the discrepancy between storm-specific totals when the rain gages recorded significantly lower totals than the SMART-R. For example, during the storm where snow was observed, the SMART-R recorded a maximum of 66% higher rainfall than the maximum recorded by the gages. Unexpectedly, the highest elevation gage, located in a pre-fire coniferous vegetation community, consistently recorded the lowest precipitation, whereas gages in the lower elevation pre- fire chaparral community recorded the highest totals. The spatial locations of the maximum rainfall inferred by the SMART-R and the terrestrial gages are also offset by 1.6 km, with terrestrial values shifted easterly. The observation that the SMART-R images high rainfall intensities recorded by rain gages suggests that this technology has the ability to quantitatively estimate the spatial distribution over larger areas at a high resolution. Discrepancies on the storm scale, however, need to be investigated further, but we are optimistic that such high resolution data from the SMART-R and the terrestrial gages may lead to the effective application of a prototype debris-flow warning system where such processes put lives at risk.

Hanshaw, M. N.; Schmidt, K. M.; Jorgensen, D. P.; Stock, J. D.

2007-12-01

276

Adjustment of radar precipitation estimation based on the kriging methods  

NASA Astrophysics Data System (ADS)

Accurate quantitative precipitation estimation (QPE) is one of the most important elements in meteorological and hydrological applications. In this study, we adjust the QPE from an S-band weather radar based on co-kringing method using the geostatistical structure function of error distribution of radar rainrate. In order to estimate accurate quantitative precipitation, the error of radar rainrate which is a primary variable of co-kriging is determined by the difference of rain rates from rain gauge and radar. Also, the gauge rainfield, a secondary variable of co-kriging is derived from the ordinary kriging based on raingauge network. The error distribution of radar rain rate is produced by co-kriging with the derived theoretical variogram determined by experimental variogram. The error of radar rain rate is then applied to the radar estimated precipitation field. Locally heavy rainfall case during 6-7 July 2009 is chosen to verify this study. Correlation between adjusted one-hour radar rainfall accumulation and rain gauge rainfall accumulation improved from 0.55 to 0.84 compared to before adjustment of radar error. And the root mean square error was adjusted from 7.45 mm to 3.93 mm.

Kim, Kwang Ho; Kwon, Byung Hyuk; Kim, Min Seong; Lee, Gyu Won; Kang, Dong Hwan

2013-04-01

277

Where to measure point rainfall during extreme flash flood events in mountainous catchments?  

Microsoft Academic Search

Despite the availability of weather radar data at high spatial (1 km^2) and temporal (5-15 min) resolution, ground-based rain gauges are still needed to accurately estimate storm rainfall input to catchments during flash flood events. This is especially true in mountainous catchments where estimating storm depth and intensity from radar data is more challenging than in flat terrain. Given economical

P. A. Troch; T. Volkmann; S. W. Lyon; H. Gupta

2009-01-01

278

Investigating Optimal Configuration of Hydrologic Models during Data Denial Situations Using Satellite Rainfall Data  

Microsoft Academic Search

Satellite-measured rainfall data can be useful during data-denial situations when conventional data sources are compromised due to natural or anthropogenic reasons. For example, hurricanes on a coastal watershed or a terrorist attack on weather radars can render the conventional rainfall measuring system for operational flood forecasting non-functional, thus making the subsequent modeling of flood very difficult. The proposed multi- national

A. Harris; F. Hossain

2006-01-01

279

Rainfall Downscaling by a Phase-Conserving, Nonlinearly-Transformed Autoregressive Model: Validation on Radar Precipitation Estimates  

Microsoft Academic Search

The prediction of the small-scale spatio-temporal pattern of intense rainfall events is crucial for flood risk assessment in small catchments and urban areas. In the absence of a full deterministic modelling of small-scale rainfall, it is common practice to resort to the use of stochastic downscaling models to generate ensemble rainfall predictions to be used as inputs to rainfall-runoff models.

N. Rebora; L. Ferraris; J. von Hardenberg; A. Provenzale

2004-01-01

280

Weathering  

NSDL National Science Digital Library

This interactive Flash resource provides information regarding physical and chemical weathering at an introductory physical geology or Earth science level. It includes animations, diagrams, and supplementary information and is suitable for high school or undergraduate students.

Smoothstone; Mifflin, Houghton

281

Evaluation of the hydrologic measure quality of the Saint Nizier weather radar data on the local urban area of Greater Lyon  

NASA Astrophysics Data System (ADS)

The meteorological radar of Saint Nizier d'Azergues, part of Meteo France network Aramis, is situated at only 40 km from the urban community of Greater Lyon, in the north of the Rhône valley, south-east of France. This area gathers many human, environmental and materials stakes and vulnerability. From an operational use, an assessment based on a simulation and analysis of real data has identified certain sectors of the community affected by problems of ground clutter, which have to be filtered before any furthermore hydrologic use. There is a very good consistency between the two types of analysis. This agreement helps to confirm the cause and extent of sources of error in the real images. These confirm the areas within the urban area affected by the phenomena of ground clutter. The list of these pixels considered less reliable, has been compiled and they were screened to very locally compare the radar values to the values of rainfall in the urban community of Lyon. Indeed, Lyon has a network of measuring the rain in urban areas among the densest in Europe, totaling about fifty rainfall stations of various organizations on its territory, which creates a density of about one rain gauge for sixteen km². In this study, only raingauges properties of the Urban Community of Lyon were used: 29 tipping bucket devices currently in operation, providing data each 6 minutes. The average rain radar on the town were calculated for the sample of 17 rain episodes from the period 2001 - 2005, and compared to average from 29 rain gauges Grand Lyon. The differences between radar estimations and rainfall values show high amplitude over time, especially in winter. Thus, a factor based on raingauges was assigned to radar data in order to match the average values and radar rainfall for each rain events. These radar adjusted data were then compared to each punctual rainfall values associated (each raingauge value has been compared to a radar pixel value associated thanks to a vertical extraction). The comparison of surface and punctual radar data to the values of the dense network of rain gauges in the community showed a small difference between these measurement values after the use of a spatial uniform weighting ratio, and filtering pixels of lower quality. Specifically, the average difference between radar data and rainfall values around 20% episodes all together, but drops to nearly 10% during exceptionally abundant or long term time rainy episodes potentially harmful. To provide complete coverage of data on the study territory, especially on ground clutter zones filtered, two spatialization techniques were used. The results of the cross validation have shown the usefulness of ordinary kriging compared to cokriging, which is a lot more complicated to use and not really better in this precise study case.

Renard, F.; Faure, D.; Comby, J.

2009-04-01

282

TRMM Radar.  

National Technical Information Service (NTIS)

The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission...

K. Okamoto

1993-01-01

283

National Weather Service  

MedlinePLUS

... CURRENT CONDITIONS Radar Climate Monitoring River Levels Observed Precipitation Surface Weather Upper Air Marine and Buoy Reports ... Weather Current Outlook Maps Drought Fire Weather Fronts/Precipitation Maps Current Graphical Forecast Maps Rivers Marine Offshore ...

284

Evaluation of the RadEst and ClimGen Stochastic Weather Generators for Low-Medium Rainfall Regions  

Microsoft Academic Search

The aim of this study is to generate the daily weather values for maximum and minimum air temperatures and solar radiation. Two well known weather generators are evaluated here. Data from the five Iranian synoptic stations having long-term weather records and dry climates have been used to compare the actual data sets with generated one. The accuracy of the different

Isaac Moradi; Kazem Nosrati; Saeid Eslamian

2007-01-01

285

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

286

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

287

Bias correction of satellite rainfall estimates using a radar-gauge product - a case study in Oklahoma (USA)  

Microsoft Academic Search

Hourly Satellite Precipitation Estimates (SPEs) may be the only available source of information for operational hydrologic and flash flood prediction due to spatial limitations of radar and gauge products. SPEs are prone to larger systematic errors and more uncertainty sources in comparison with ground based radar and gauge precipitation products. The present work develops an approach to seamlessly blend satellite,

K. Tesfagiorgis; S. E. Mahani; N. Y. Krakauer; R. Khanbilvardi

2011-01-01

288

Quantitative Real-Time Rainfall Forecasting Using Remote Sensing.  

NASA Astrophysics Data System (ADS)

A physically-based rainfall forecasting model for real-time hydrologic applications is developed with emphasis on utilization of remote sensing observations. Radar measured reflectivities, satellite measured brightness temperatures, and surface meteorologic observations are the primary model input quantities. Temporal and spatial scales of interest are lead-times of one-hour and regions on the order of 10-10000 km^2. The model is derived from the principles of conservation of mass for vertically integrated liquid water content in a cloud. Model dynamics are governed by a nonlinear relationship between meteorological input quantities and the model state. To develop a means of accounting for uncertainty in model formulation and measurements, a Kalman filter is incorporated to couple model forecasts with observed quantities. Because implementation of the filter requires a linear system, a statistical-linearization technique is applied to the model dynamics. The Kalman filter state estimator allows real-time updating of the model state and estimation of forecast uncertainty. A calibration study is performed to define guidelines for parameter estimation, evaluate the working range for model parameter values, and select model parameter values for model verification. The model is calibrated and verified using observed data. The observed data includes: radar data collected at the National Weather Service radar site in Oklahoma City; satellite data obtained from the GOES -7 infrared band; and ground level meteorological data obtained from weather stations in the region of the radar site. Results indicate that one-hour lead-time rainfall rate forecasts produced using the calibrated model are of comparable or higher accuracy than forecasts obtained using traditional methods such as persistence or advection -based nowcasting. The performance measures used to evaluate forecast quality include: mean rainfall rate error; root mean square error of rainfall rate; percent of correctly forecasted rainfall coverage; and cross-correlation between forecasted and observed rainfall fields.

French, Mark Nelson

1992-01-01

289

Estimating Rainfall One Pixel at a Time: A Scientific Activity with Brazilian Students  

NASA Astrophysics Data System (ADS)

Studies of rainfall and precipitation using radars started almost at the same time as radars were developed for military applications in Second World War. Since then, the science behind radars used to monitor weather has evolved constantly. Radar images showing clouds, different types of precipitation, motion and evolution of weather systems are commonplace nowadays and are present in all forms of mass communication. Unfortunately, the layperson and even science students have limited knowledge of how weather radars work, how radar images are produced and what they do really mean. In order to increase the awareness about the use of radars in meteorology and interpretation of images, we started a program to teach science students on how to analyze radar images and to obtain simple estimates of rainfall using radar images alone. The data for the study was collected by a non-polarimetric Doppler radar operating on the C-Band The procedure is simple, radar images are selected, areas of interest (rain cells) are marked and then the color pixels in images are separated and counted according to their color and precipitation index. In this way, the evolution of the rain cell is followed and the amount of precipitation is calculated. As an additional activity, in a reverse analysis process, values of reflectivity are obtained from the estimates of precipitation and the size distribution of rain cloud droplets are calculated using parametric equations. This study was both rewarding and enriching for the students because they could participate in the actual process of collecting and analyzing the data, and the lessons learned and experience gained with this hands-on activity will certainly constitute a valuable asset.

Alves, M. A.; Martin, I. M.; Lyra, C. S.

2009-12-01

290

Rain in Shallow and Deep Convection Measured with a Polarimetric Radar  

Microsoft Academic Search

The authors contrast rainfall in two Oklahoma squall lines: one with deep convection occurred in the spring and the other with shallower convection in the winter. Both passed over a micronetwork of densely spaced rain gauges and were observed with the National Severe Storm Laboratory's polarimetric weather radar. Polarimetric measurements reveal differences in storm structure that in turn imply that

Alexander V. Ryzhkov; Dusan S. Zrni

1996-01-01

291

Terminal doppler weather radar (TDWR) build 5B operational test and evaluation (OT&E) integration and OT&E operational test plan  

Microsoft Academic Search

The Terminal Doppler Weather Radar (TDWR) Build 5B Enhancement Operational Test and Evaluation (OT&E) Integration and OT&E Operational Test Plan provides the overall philosophy and approach to Build 5B OT&E testing, and identifies OT&E objectives, responsibilities, and resources. The TDWR Build 5B Enhancement provides connectivity to the Low Level Wind Shear Alert System (LLWAS) III to display LLWAS III data

Radame Martinez; Steven Viveiros; Donne Wedge; Peter Guthlein

1995-01-01

292

The potential for hail and intense rainfall enhancement over urban areas: improving urban extreme weather risk assessment  

Microsoft Academic Search

Urban communities and their infrastructure are particularly vulnerable to the impacts of organized thunderstorm systems. Current models of urban extreme weather risk do not fully represent the complexity of the hydrometeorological processes involved, particularly in relation to intense convective precipitation and severe weather. Hail is a severe thunderstorm hazard that can be extremely damaging to property (especially automobiles, buildings and

A. A. Ntelekos; J. A. Smith; W. F. Krajewski; M. Foote

2009-01-01

293

Anvil Generation and Rainfall Variability in South Florida and the Surrounding Ocean  

NASA Astrophysics Data System (ADS)

Anvil clouds, generated from deep convective storms, make up an important component of the global heat balance particularly in the Tropics. This observational study examined the relationship between near-surface rainfall and upper-level anvil clouds associated with sub-tropical convective systems. Observations from four National Weather Service NEXRAD and the NASA N-POL polarimetric radar were used to construct a three-dimensional radar reflectivity composite dataset over South and Central Florida, and surrounding ocean regions, during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE). CRYSTAL-FACE took place during the month of July 2002. Radar- derived rainfall for this 30-day period is analyzed for land and ocean regions. Power spectra of rainfall time series (convective and stratiform) revealed differences in high frequency (e.g. diurnal) rainfall variability for land vs. ocean regions. These are contrasted with power spectra of radar reflectivity in the upper troposphere, associated with thick anvil clouds, to examine the diurnal variation of the anvil portion of the convective systems. Over land, the diurnal maximum in the upper level anvil area lags by several hours the low-level radar- derived rainfall. This result is not as well defined over ocean, where the diurnal variation of convective systems is more complex. Illustrative case studies will be presented. These results have implications for the representation of anvil cloud generation in climate model studies.

Rickenbach, T.; Strenfel, S.; Kucera, P.; Noble, J.; Starr, D.

2006-12-01

294

Ground Penetrating Radar as a Means of Studying Palaeofault Scarps in a Deeply Weathered Terrain, Southwestern Western Australia  

NASA Astrophysics Data System (ADS)

The southwest seismic zone is a region of concentrated intra-plate seismicity in the southwest of Western Australia. The regional geology consists of Archean granitoids covered by a thick, electrically conductive, mantle of in situ weathered material and transported cover. Numerous palaeofault scarps have been recognised in the region, primarily based on remote sensing data. These scarps occur in an area more extensive than the historic region of seismic activity, implying that large seismic events can occur outside the current seismic zone, which has important implications for the estimation of seismic hazard. Ground penetrating radar (GPR) has been used to study Recent faulting in various parts of the world, and been shown to be capable of imaging features associated with the fault, e.g. colluvial wedges, disrupted and displaced strata. However, the majority of studies are of normal and/or strike-slip faults and there are no studies demonstrating the method works in electrically conductive, deeply weathered terrains. GPR data have been collected in Western Australia across confirmed two palaeofault scarps (Hyden and Dumbelyung) and also the scarp created by the 1968 Meckering earthquake. In each case there is a nearby trench to allow GPR responses to be related to known geology. At Meckering and Hyden, where the near-surface material contains moderate amounts of clay and the groundwater is fresh, it has proved possible to collect high quality data that images colluvium and also disrupted bedrock features which allow faults to be inferred. At Dumbelyung, where the near surface is more conductive due to clay-rich alluvial deposits and saline groundwater, results were less good and no sub-surface features were confidently identified, although the general geometry of the stratigraphy was imaged. Our results demonstrate that GPR surveys can be a valuable tool for studying palaeofaults in deeply weathered terrains, although this is subject to the local ground conditions. Even in what is considered a hostile environment for the method, GPR data can confirm whether a topographic feature is of seismic origin, and image features in sufficient detail to enable siting of trenches for palaeoseismic studies.

Dentith, M. C.; O'Neill, A.; Clark, D.

2009-12-01

295

A feasibility study of rain radar for the Tropical Rainfall Measuring Mission. IV - A discussion of pulse compression and adaptive scanning  

NASA Astrophysics Data System (ADS)

The possible use of a pulse compression system on the Tropical Rainfall Measuring Mission to meet the requirement on the number of independent samples for the rain radar under the constraint on allowable power consumption. The applicability of a pulse compression system to the mission depends on the technological feasibility of reducing the range sidelobe levels of the strong surface echo down to at least -60 dB. It is found that applying the pulse compression technique to the mission is risky. The concept of adaptive scanning is examined, and its power saving efficiency is numerically evaluated for four kinds of rain searching schemes. It is shown that the power saving efficiency of adaptive scanning is considerably high for all the rain searching schemes evaluated.

Ihara, Toshio; Nakamura, Kenji

1988-07-01

296

Regional cloud characteristics over the tropical northwestern Pacific as revealed by Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar and TRMM Microwave Imager  

NASA Astrophysics Data System (ADS)

The present study investigates regional cloud characteristics over the tropical northwestern Pacific using Tropical Rainfall Measuring Mission (TRMM) data sets such as rain rate, radar reflectivity, and passive microwave radiometer polarization corrected temperature (PCT). In particular, the tropical northwestern Pacific is divided into two surface rain maxima regions: the South China Sea (SCS) and the Philippine Sea (PS). The TRMM variables are retrieved by a pair of spaceborne microwave sensors, Precipitation Radar (PR) and TRMM Microwave Imager (TMI). It is revealed that the SCS contains more frequent deeply developed convective systems relative to the PS on the basis of the analysis of the PR and TMI version-6 data during a 4-year period (1998-2001) of summers. This is mainly indicated by two factors: strong PR reflectivity (?30 dBZ) above the freezing level (˜5 km) and TMI ice-scattering signature (PCT at 85.5 GHz ? ˜190 K, and PCT at 37.0 GHz ? ˜260 K), which are more frequent over the SCS than over the PS. Comparison of TMI and PR rain rates, a relatively small (large) positive PR-TMI bias is observed for an average of rainy areas over the SCS (PS). This region-dependent PR-TMI bias can arise from the regionally different extents of both (1) the PR's underestimate by attenuation correction and (2) the TMI's overestimate by emission from the melting layer (i.e., SCS > PS in (1) and (2)). These differences are due to the excess of heavy rainfall events, high rain rates, strong convective intensities, and high cloud top heights in the SCS compared with the PS.

Park, Myung-Sook; Choi, Yong-Sang; Ho, Chang-Hoi; Sui, Chung-Hsiung; Park, Seon Ki; Ahn, Myoung-Hwan

2007-03-01

297

Evaluation of the RadEst and ClimGen Stochastic Weather Generators for Low-Medium Rainfall Regions  

NASA Astrophysics Data System (ADS)

The aim of this study is to generate the daily weather values for maximum and minimum air temperatures and solar radiation. Two well known weather generators are evaluated here. Data from the five Iranian synoptic stations having long-term weather records and dry climates have been used to compare the actual data sets with generated one. The accuracy of the different weather generators models was evaluated by means of three widely used statistics: Correlation coefficient (R), Root Mean Square Error (RMSE) and Mean Bias Error (MBE). For maximum and minimum temperatures, Bushehr`s data show the lowest RMSE and Esfahan`s data show the highest RMSE. For radiation data, RMSEs of all of the stations are very high, except for Esfahan station. In general, the computed values of temperature are in good agreement with the data derived by the observation, but the computed values for radiation do not indicate a good agreement with the measured data.

Moradi, Isaac; Nosrati, Kazem; Eslamian, Saeid

298

Rainfall Generator for the Rhine Basin. Multi-Site Generation of Weather Variables by Nearest-Neighbour Resampling.  

National Technical Information Service (NTIS)

This report presents the second phase of a project on the development of a rainfall generator for the Rhine basin. The request for this generator arose from the need to study the likelihood of extreme river discharges in the Netherlands, using a hydrologi...

T. Brandsma T. A. Buishand

1999-01-01

299

Rainfall Generator for the Rhine Basin. Multi-Site Generation of Weather Variables for the Entire Drainage Area.  

National Technical Information Service (NTIS)

This is the final report of a project on the development of a rainfall generator for the Rhine basin. The request for this generator arose from the need to study the likelihood of extreme river discharges in the Netherlands, using a hydrological/hydraulic...

R. Wojcik J. J. Beersma T. A. Buishand

2000-01-01

300

Development of Multisensor Precipitation Nowcaster in the National Weather Service  

NASA Astrophysics Data System (ADS)

To meet the National Oceanic and Atmospheric Administration (NOAA) objective to increase lead-time and accuracy of flash flood forecasts, the NOAA National Weather Service (NWS) Office of Hydrologic Development has developed the Multisensor Precipitation Nowcaster (MPN) algorithm based on its Flash Flood Potential algorithm. In contrast to many existing nowcast algorithms that are single-radar-based, MPN integrates and mosaics data from multiple radars to provide seamless regional gridded rainfall nowcast products that alleviate known problems in estimating and nowcasting rainfall resulting from range-related degradation of rainfall estimates. Even for local forecasting operations, forecasters can benefit from MPN by viewing data from multiple radars simultaneously and by using it to evaluate possible upstream features which are distant from the local radar. Instead of using radar-only rainfall estimates as its input, MPN uses rain gauge-adjusted rainfall estimates from the Multisensor Precipitation Estimator (MPE) algorithm that have been adjusted for possible biases using real-time gauge data. An example in the region of the Middle Atlantic River Forecast Center is used to demonstrate MPN short term quantitative precipitation forecasts using a multisensor approach and multiple radars. The rain rates observed by radars are adjusted according rain gauge data to remove the bias and are mosaicked by MPE. MPN uses those data as input and forecasts 1-hour accumulated precipitation and 0-1 hour rain rates. Our results indicate that MPN can produce 1-hour quantitative precipitation forecasts that substantially improve the probability of detection, the false-alarm rate, the critical success index, the correlation coefficient, and the root mean square error when compared with persistence methods. This study and our other studies confirm that MPN improves lead-time and accuracy of precipitation forecasts and is suitable for operational implementation.

Guan, S.; Fulton, R.; Ding, F.; Kitzmiller, D.

2006-05-01

301

Relationships between topography and precipitation at very high resolution in the tropics: insights from Tropical Rainfall Measuring Mission (TRMM) precipitation radar data (Invited)  

NASA Astrophysics Data System (ADS)

Interactions between spatial variability in precipitation and evolving topography have been proposed in several mountain ranges including the Himalaya and Andes. We present and evaluate precipitation data from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) algorithm 2A25 version 6 and examine the spatial relationships between precipitation and topography. Ten years (1998-2007) of tropics-wide (±36° latitude) near-surface rain data are used to construct a high resolution (~10 km) map of average annual rainfall. An error model is developed by sub-sampling the TRMM Multi-satellite Precipitation Analysis as sampled by the PR. The error model predicts observed sampling error as a function of resolution, rain rate and sampling frequency with an r 2 of 0.82. This error model indicates that precipitation gradients at the 10 km scale are resolved in regions with large average daily rain totals including portions of the Andes, Himalaya and Western Ghats. Knowledge of the relationship between precipitation patterns and topography in these regions is crucial for evaluating the importance of orographic precipitation for landscape evolution.

Anders, A. M.; Nesbitt, S. W.

2009-12-01

302

Radar Analyses of Space-Time Variability of Rainfall for Extreme Flood-Producing Storms in an Urban Environment  

Microsoft Academic Search

The Charlotte, North Carolina metropolitan area has experienced extensive urban and suburban growth during the past 40 years, resulting in increasing flood hazards in the region. Record flooding in the urban core of Charlotte occurred on 23 July 1997 from a storm that produced rainfall accumulations of more than 250 mm during an 18 hour period, more than doubling 24

G. Villarini; J. A. Smith; M. Baeck; P. L. Sturdevant Rees; W. F. Krajewski

2008-01-01

303

Radar Analyses of Space-Time Variability of Extreme Flood-Producing Rainfall in Urban Drainage Basins  

Microsoft Academic Search

The Charlotte, North Carolina metropolitan area has experienced extensive urban and suburban growth during the past 40 years, resulting in increasing flood hazards in the region. Record flooding in the urban core of Charlotte occurred on 23 July 1997 from a storm that produced rainfall accumulations of more than 250 mm during an 18 hour period, more than doubling the

G. Villarini; J. A. Smith; M. L. Baeck; P. Sturdevant-Rees; W. F. Krajewski

2009-01-01

304

Estimation of extreme floods of the River Meuse using a stochastic weather generator and a rainfall–runoff model \\/ Estimation des crues extrêmes de la Meuse à l'aide d'un générateur stochastique de variables météorologiques et d'un modèle pluie–débit  

Microsoft Academic Search

A stochastic weather generator has been developed to simulate long daily sequences of areal rainfall and station temperature for the Belgian and French sub-basins of the River Meuse. The weather generator is based on the principle of nearest-neighbour resampling. In this method rainfall and temperature data are sampled simultaneously from multiple historical records with replacement such that the temporal and

Robert Leander; Adri Buishand; Paul Aalders; Marcel De Wit

2005-01-01

305

Analysis of warm season thunderstorms using an object-oriented tracking method based on radar and total lightning data  

Microsoft Academic Search

Monitoring thunderstorms activity is an essential part of operational weather surveillance given their potential hazards, including lightning, hail, heavy rainfall, strong winds or even tornadoes. This study has two main objectives: firstly, the description of a methodology, based on radar and total lightning data to characterise thunderstorms in real-time; secondly, the application of this methodology to 66 thunderstorms that affected

T. Rigo; N. Pineda; J. Bech

2010-01-01

306

Comment on "Geomorphic hazards and intense rainfall: the case study of the Recco Stream catchment (Eastern Liguria, Italy)" by Faccini et al. (2012)  

NASA Astrophysics Data System (ADS)

Faccini et al. (2012) describe an intense rainstorm that caused a flash flood and triggered landslides in a sector of Eastern Liguria (Italy) on 1 June 2007 and discuss the implications for geomorphic hazard assessment and land use planning. This comment points out some weaknesses in the use of weather radar for the assessment of rainfall and in the documentation of flood response.

Marchi, L.

2012-10-01

307

Cloud and Precipitation Radar  

NASA Astrophysics Data System (ADS)

Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

308

A combined passive–active microwave retrieval of quantitative rainfall from Topex\\/Poseidon radar altimeter and Topex microwave radiometer  

Microsoft Academic Search

Synergistic measurements of both active and passive nadir looking microwave sensors onboard Topex\\/Poseidon (T\\/P) satellite are explored for their instantaneous rain estimation capability over tropical oceans. Data of T\\/P altimeter (the differential radar backscatter at C and Ku band frequencies, i.e. ??°?=??°C??°Ku), and Topex microwave radiometer (TMR) (brightness temperatures at 18, 21 and 37?GHz frequencies) coincident with special sensor microwave\\/imager

R. M. Gairola; S. Pokhrel; A. K. Varma; Vijay K. Agarwal

2005-01-01

309

The Use of Millimeter Doppler Radar Echoes to Estimate Vertical Air Velocities in the Fair-Weather Convective Boundary Layer  

Microsoft Academic Search

Vertical velocity characteristics of the optically clear convective boundary layer (CBL) are examined by means of profiling airborne radar data collected in the central Great Plains during the International H2O Project, May-June 2002 (IHOP 2002). Clear-air echoes are sufficiently strong for the radar, a 95-GHz cloud radar, to detect most of the CBL at a resolution of 30 m. Vertical

Bart Geerts; Qun Miao

2005-01-01

310

Flood Monitoring using X-band Dual-polarization Radar Network  

NASA Astrophysics Data System (ADS)

A dense weather radar network is an emerging concept advanced by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). Using multiple radars observing over a common will create different data outcomes depending on the characteristics of the radar units employed and the network topology. To define this a general framework is developed to describe the radar network space, and formulations are obtained that can be used for weather radar network characterization. Current weather radar surveillance networks are based upon conventional sensing paradigm of widely-separated, standalone sensing systems using long range radars that operate at wavelengths in 5-10 cm range. Such configuration has limited capability to observe close to the surface of the earth because of the earth's curvature but also has poorer resolution at far ranges. The dense network radar system, observes and measures weather phenomenon such as rainfall and severe weather close to the ground at higher spatial and temporal resolution compared to the current paradigm. In addition the dense network paradigm also is easily adaptable to complex terrain. Flooding is one of the most common natural hazards in the world. Especially, excessive development decreases the response time of urban watersheds and complex terrain to rainfall and increases the chance of localized flooding events over a small spatial domain. Successful monitoring of urban floods requires high spatiotemporal resolution, accurate precipitation estimation because of the rapid flood response as well as the complex hydrologic and hydraulic characteristics in an urban environment. This paper reviews various aspects in radar rainfall mapping in urban coverage using dense X-band dual-polarization radar networks. By reducing the maximum range and operating at X-band, one can ensure good azimuthal resolution with a small-size antenna and keep the radar beam closer to the ground. The networked topology helps to achieve satisfactory sensitivity and fast temporal update across the coverage. Strong clutter is expected from buildings in the neighborhood which act as perfect reflectors. The reduction in radar size enables flexible deployment, such as rooftop installation, with small infrastructure requirement, which is critical in a metropolitan region. Dual-polarization based technologies can be implemented for real-time mitigation of rain attenuations and accurate estimation of rainfall. The NSF Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is developing the technologies and the systems for network centric weather observation. The Differential propagation phase (Kdp) has higher sensitivity at X-band compared to S and C band. It is attractive to use Kdp to derive Quantitative Precipitation Estimation (QPE) because it is immune to rain attenuation, calibration biases, partial beam blockage, and hail contamination. Despite the advantage of Kdp for radar QPE, the estimation of Kdp itself is a challenge as the range derivative of the differential propagation phase profiles. An adaptive Kdp algorithm was implemented in the CASA IP1 testbed that substantially reduces the fluctuation in light rain and the bias at heavy rain. The Kdp estimation also benefits from the higher resolution in the IP1 radar network. The performance of the IP1 QPE product was evaluated for all major rain events against the USDA Agriculture Research Service's gauge network (MicroNet) in the Little Washita watershed, which comprises 20 weather stations in the center of the test bed. The cross-comparison with gauge measurements shows excellent agreement for the storm events during the Spring Experiments of 2007 and 2008. The hourly rainfall estimates compared to the gauge measurements have a very small bias of few percent and a normalized standard error of 21%. The IP1 testbed was designed with overlapping coverage among its radar nodes. The study area is covered by multiple radars and the aspect of network composition is also evaluated. The independence of Kdp on the radar calibration e

Chandrasekar, V.; Wang, Y.; Maki, M.; Nakane, K.

2009-09-01

311

Comparison of Spatial and Temporal Rainfall Characteristics in WRF-Simulated Precipitation to Gauge and Radar Observations  

EPA Science Inventory

Weather Research and Forecasting (WRF) meteorological data are used for USEPA multimedia air and water quality modeling applications, within the CMAQ modeling system to estimate wet deposition and to evaluate future climate and land-use scenarios. While it is not expected that hi...

312

Terminal doppler weather radar (TDWR) build 5B operational test and evaluation (OT&E) integration and OT&E operational test plan  

NASA Astrophysics Data System (ADS)

The Terminal Doppler Weather Radar (TDWR) Build 5B Enhancement Operational Test and Evaluation (OT&E) Integration and OT&E Operational Test Plan provides the overall philosophy and approach to Build 5B OT&E testing, and identifies OT&E objectives, responsibilities, and resources. The TDWR Build 5B Enhancement provides connectivity to the Low Level Wind Shear Alert System (LLWAS) III to display LLWAS III data along with TDWR hazardous weather data on TDWR Geographic Situation Displays (GSD) and Ribbon Display Terminals (RDT). The TDWR Build 5B OT&E is scheduled to occur at the TDWR sites in Denver, CO, November and December 1994, and in Orlando, FL, spring 1995.

Martinez, Radame; Viveiros, Steven; Wedge, Donne; Guthlein, Peter

1995-03-01

313

Autocorrelation and Error Structure of Rainfall Derived from NEXRAD in Central and South Florida  

NASA Astrophysics Data System (ADS)

Motivation for this study comes from the South Florida Water Management District (District) who is responsible for managing water resources in 16-counties over a 46,439-square kilometer (17,930 square-mile) area. Near-real- time rainfall data are used in operation of approximately 3,000 kilometers (~1,800 miles) of canals, 22 major pump stations and 200 water control structures. The spatial extent of the District extends from Orlando to Key West and from the Gulf Coast to the Atlantic Ocean and contains major water features including Lake Okeechobee and the Everglades wetlands. Rainfall is a key factor in the water management decisions made by the District in real-time and through studies that rely on archival rainfall data derived from radar and rain gauge observations. Rainfall measurements are obtained from a combination of four NEXRAD radars and a rain gauge network that comprises 280 active rain gauge stations located in the more populated areas. Four NEXRAD (Next Generation Weather Radar) sites operated by the National Weather Service cover the region. Rain gauges are used for frequency analysis and for adjustment of the radar rainfall products. An optimization study of the rain gauge network is accomplished by removing gauges in areas of excess coverage, and by adding or moving rain gauges to gain a more even spatial distribution over the District. Rainfall fields measured at daily and hourly timesteps exhibit autocorrelation which can affect the network design subject to optimality constraints. This presentation will describe the autocorrelation and error structure found in rainfall measurements derived from rain gage and NEXRAD data. The data used in the analysis includes rain gage data and the NEXRAD rainfall data that was collected during 1995-2005 at 2 x 2 km resolution. A set of clusters of rain gages and a regular array of analysis blocks that were 20 x 20 km in size for the NEXRAD data were used to account for variability of the rainfall processes and local rainfall patterns. The spatial autocorrelations of the rain gage and NEXRAD rainfall were identified using a semivariogram approach at daily timescale. The model fitting to the semivariograms were performed on data from 1998-2005. The spatial autocorrelations from rain gage and NEXRAD rainfall data sets were compared and evaluated.

Pathak, C. S.; Vieux, B. E.

2007-12-01

314

Reflectivity and Differential Reflectivity Rainfall Algorithm Performance at X-band  

Microsoft Academic Search

X-band weather radar systems present several advantages mainly related to their lower cost and smaller size relative to their S and C band counterparts. The main drawback of X-band is the attenuation suffered by the electromagnetic wave propagating through precipitation that reduces the reliability of rainfall estimates based on power measurements. Developments in dual-polarization techniques have provided solutions to mitigate

Eugenio Gorgucci; Luca Baldini; V. Chandrasekar; Minda Le

2008-01-01

315

The effectiveness of adaptive PRF (Pulse Repetition Frequency) selection in minimizing range obscuration in the TDWR (Terminal Doppler Weather Radar) system  

NASA Astrophysics Data System (ADS)

An adaptive procedure for selecting radar pulse repetition frequency (PRF) has been developed as the primary means of minimizing the occurrence of range aliased echoes within operationally significant coverage areas (e.g., airport runways) of the Terminal Doppler Weather Radar (TDWR) system. This procedure underwent extensive testing at the S-Band TDWR testbed while located in Denver, CO, where it was judged to be highly successful at preserving the integrity of data collected within the vicinity of the Stapleton International Airport runways. The actual TDWR system will operate at a C-Band frequency, and an increase in potential range obscuration is expected over that experienced by the S-band testbed. This report discusses the anticipated performance of the PRF selection procedure in the C-Band environment by extrapolating results obtained using S-Band testbed data. The results conclusively demonstrates the efficacy of adaptive PRF selection as a method by which to reduce potential range obscuration. A worst-case scenario, for example, indicates that over 20 percent of the TDWR radar data collected about the airport runways has the potential for being contaminated with range aliased echoes at any given time during TDWR surveillance operations. With adaptive PRF selection, however, the expected obscuration is reduced to only 3 percent.

Crocker, S. C.

1989-07-01

316

A Comparison of Cloud and Rainfall Information from Instantaneous Visible and Infrared Scanner and Precipitation Radar Observations over a Frontal Zone in East Asia during June 1998.  

NASA Astrophysics Data System (ADS)

The comparison between cloud information and rainfall is studied using infrared and radar data from the Tropical Rainfall Measuring Mission. Cloud information from the visible and infrared scanner was compared with rain information from precipitation radar (PR) for rain cases assembled during June 1998 over a frontal zone in east Asia. The authors selected the following four parameters: 1) radiance ratio of 0.6 and 1.6 m [channel 1/channel 2 (Ch1/Ch2)], 2) brightness temperature difference between 11 and 12 m (BTD45), 3) brightness temperature difference between 3.8 and 11 m (BTD34), and 4) brightness temperature (TBB) in channel 4 (Ch4) as the cloud information. The flags of `rain certain,' stratiform rain, brightband existence, and convective rain observed by PR, and integrated rain rate from the rain bottom to rain top were used as the rainfall information.From the comparison between rain-no-rain information by PR and the four cloud parameters, it is found that values of the radiance ratio of Ch1/Ch2 larger than 25, BTD45 smaller than 1.5 K, and BTD34 smaller than 8 K are effective in delineating rain area. The probability of detection (POD), false alarm ratio (FAR), and skill score (SS) are computed and compared for the following rain and no-rain algorithms: 1) single cloud threshold of 235 K in Ch4 TBB as in the Geostationary Operational Environmental Satellite Precipitation Index, 2) single threshold of 260 K in Ch4 TBB, 3) Ch1/Ch2 larger than 25 and Ch4 TBB colder than 260 K (C12), 4) BTD45 smaller than 1.5 K and Ch4 TBB colder than 260 K (C45), and 5) BTD34 smaller than 8 K and Ch4 TBB colder than 260 K. The C12 method shows the highest SS, and the C45 method shows the highest POD. The BTD34 scores better in FAR than the BTD45 and is better than BTD45 in delineating the thicker part of cirrus clouds. The use of the second channel shows better scores than does use of the single infrared threshold algorithm.The cloud characteristics for convective rain and stratiform rain are also studied using Ch1/Ch2, BTD45, and BTD34. The percentage of occurrence of stratiform rain shows a local maximum for clouds of small BTD45/BTD34 with Ch4 TBB of 220-250 K. The higher percentage of convective rain corresponds well to the optically thicker (smaller BTD45) clouds colder than 210 K. However, there is no significant difference in Ch1/Ch2 between convective and stratiform rain, because significant convective cases are not included in the data that were processed.

Inoue, Toshiro; Aonashi, Kazumasa

2000-12-01

317

Satellite Observations For Calibration of Ground Radar Networks  

NASA Astrophysics Data System (ADS)

Calibration differences between weather service ground radars is one source of error that can lead to bias in quantitative precipitation estimates. In the U.S., calibration differences among Weather Service Radar-1988 Doppler (WSR-88D) radars are know to vary by up to several decibels in reflectivity. Such differences have been shown to cause significant radar-to-radar observation differences, and can lead to significant error in precipitation estimates. The calibration of 21 WSR-88D radars in the southeast U.S. was assessed using methods developed for NASA's Global Precipitation Mission (GPM) Validation Network (VN) prototype. The VN performs geometric matching of Precipitation Radar (PR) data from the Tropical Rainfall Measuring Mission (TRMM) satellite to ground radars. The VN geometric matching method averages PR reflectivity (both raw and attenuation corrected) and rain rate, and ground radar (GR) reflectivity at the geometric intersection of the PR rays with the individual GR elevation sweeps. The algorithm thus averages the minimum PR and GR sample volumes needed to ''matchup'' the spatially coincident PR and ground radar data types. This geometric matching method has been demonstrated to out-perform gridding techniques by providing better estimates of GR-to-PR bias. TRMM PR data were used as the calibration reference because analyses of the PR performance estimated the instrument calibration to be stable and accurate to within less than 1dBZ (3-sigma). The calibration accuracy of the 21 WSR-88D radars was assessed for the period of record from August 2006 to July 2011. For purposes of calibration assessments, the data were restricted to PR-GR match-up volumes >750m above the bright band in stratiform rain areas where PR radar attenuation is not at issue. Based on space and ground radar matchups, most WSR-88D radars were found to have a mean PR-GR bias of less than 1 dBZ. Several adjacent WSR-88D sites near or along the Gulf Coast between Louisiana and Florida (KLCH, KLIX, KSHV, KTBW, and KTLH) exhibit a PR-GR bias of -1 dBZ or lower, indicating a positive calibration offset of the WSR-88D radar. This set of Gulf Coast radars, KEVX and KMOB excepted, seem to be well calibrated to one another, but run ''hot'' compared to the other WSR-88D sites in the VN subset. Additional analyses were performed to examine the temporal variability of mean PR-GR reflectivity differences to identify ground radar calibration drift. Several sites (KAMX, KBYX, KCRP, and KMLB) show consistent, small biases with respect to the PR, indicating a stable calibration of these WSR-88D systems.

Schwaller, M.; Morris, K.

2011-12-01

318

Doppler Radar Profilers as Calibration Tools for Scanning Radars.  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration's Aeronomy Laboratory has modified a standard 915-MHz profiler for use as a precipitation profiler in support of Tropical Rainfall Measuring Mission ground validation field campaigns. This profiler was modified to look vertically with a fixed dish antenna. It was operated during the Texas and Florida Underflights Experiment (TEFLUN) A in south Texas in April-May 1998 and during TEFLUN B in central Florida in August-September 1998. Collocated with the profiler was a Distromet, Inc., RD-69 Joss-Waldvogel disdrometer in Texas and Florida and a two-dimensional video disdrometer in Florida. The disdrometers are used to calibrate the profiler at the lowest range gates. At higher altitudes, the calibrated profiler reflectivities are compared with observations made by scanning radars such as the Weather Surveillance Radar-1988 Doppler in Dickinson, Texas, and Melbourne, Florida, and the S-band Doppler dual-polarization radar in Florida. The authors conclude that it is possible to use profilers as transfer standards to calibrate and to validate the reflectivities measured by the scanning radars.

Gage, Kenneth S.; Williams, Christopher R.; Johnston, Paul E.; Ecklund, Warner L.; Cifelli, Robert; Tokay, Ali; Carter, David A.

2000-12-01

319

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.

320

Rainfall and temperature distinguish between Karnal bunt positive and negative years in wheat fields in Texas.  

PubMed

Karnal bunt of wheat, caused by the fungus Tilletia indica, is an internationally regulated disease. Since its first detection in central Texas in 1997, regions in which the disease was detected have been under strict federal quarantine regulations resulting in significant economic losses. A study was conducted to determine the effect of weather factors on incidence of the disease since its first detection in Texas. Weather variables (temperature and rainfall amount and frequency) were collected and used as predictors in discriminant analysis for classifying bunt-positive and -negative fields using incidence data for 1997 and 2000 to 2003 in San Saba County. Rainfall amount and frequency were obtained from radar (Doppler radar) measurements. The three weather variables correctly classified 100% of the cases into bunt-positive or -negative fields during the specific period overlapping the stage of wheat susceptibility (boot to soft dough) in the region. A linear discriminant-function model then was developed for use in classification of new weather variables into the bunt occurrence groups (+ or -). The model was evaluated using weather data for 2004 to 2006 for San Saba area (central Texas), and data for 2001 and 2002 for Olney area (north-central Texas). The model correctly predicted bunt occurrence in all cases except for the year 2004. The model was also evaluated for site-specific prediction of the disease using radar rainfall data and in most cases provided similar results as the regional level evaluation. The humid thermal index (HTI) model (widely used for assessing risk of Karnal bunt) agreed with our model in all cases in the regional level evaluation, including the year 2004 for the San Saba area, except for the Olney area where it incorrectly predicted weather conditions in 2001 as unfavorable. The current model has a potential to be used in a spray advisory program in regulated wheat fields. PMID:18943243

Workneh, F; Allen, T W; Nash, G H; Narasimhan, B; Srinivasan, R; Rush, C M

2008-01-01

321

Dissolved rainfall inputs and streamwater outputs in an undisturbed watershed on highly weathered soils in the Brazilian cerrado  

NASA Astrophysics Data System (ADS)

The cerrados of Brazil cover 2 million km2. Despite the extent of these seasonally dry ecosystems, little watershed research has been focused in this region, particularly relative to the watersheds of the Amazon Basin. The cerrado shares pedogenic characteristics with the Amazon Basin in draining portions of the Brazilian shield and in possessing Oxisols over much of the landscape. The objective of this research was to quantify the stream water geochemical relationships of an undisturbed 1200 ha cerrado watershed for comparison to river geochemistry in the Amazon. Furthermore, this undisturbed watershed was used to evaluate stream discharge versus dissolved ion concentration relationships. This research was conducted in the Córrego Roncador watershed of the Reserva Ecológica do Roncador (RECOR) of the Instituto Brasileiro Geografia e Estatística (IBGE) near Brasilia, Brazil. Bulk precipitation and stream water chemistry were analysed between May 1998 and May 2000. The upland soils of this watershed are nutrient poor possessing total stocks of exchangeable elements in the upper 1 m of 81 +/- 13, 77 +/- 4, 25 +/- 3, and 1 +/- 1 kg ha-1 of K, Ca, Mg, and P, respectively. Bulk precipitation inputs of dissolved nutrients for this watershed are low and consistent with previous estimates. The nutrient-poor soils of this watershed, however, increase the relative importance of precipitation for nutrient replenishment to vegetation during episodes of ecosystem disturbance. Stream water dissolved loads were extremely dilute with conductivities ranging from 4 to 10 ?S cm-1 during periods of high- and low-flow, respectively. Despite the low concentrations in this stream, geochemical relationships were similar to other Amazonian streams draining shield geologies. Discharge-concentration relationships for Ca and Mg in these highly weathered soils developed from igneous rocks of the Brazilian shield demonstrated a significant negative relationship indicating a continued predominance of groundwater baseflow contributions these cationic elements.

Markewitz, Daniel; Resende, Julio C. F.; Parron, Lucilia; Bustamante, Mercedes; Klink, Carlos A.; Figueiredo, Ricardo De O.; Davidson, Eric A.

2006-08-01

322

Hydrometeor classification from dual-polarized weather radar: extending fuzzy logic from S-band to C-band data  

NASA Astrophysics Data System (ADS)

A model-based fuzzy classification method for C-band polarimetric radar data, named Fuzzy Radar Algorithm for Hydrometeor Classification at C-band (FRAHCC), is presented. Membership functions are designed for best fitting simulation data at C-band, and they are derived for ten different hydrometeor classes by means of a scattering model, based on T-Matrix numerical method. The fuzzy logic classification technique uses a reduced set of polarimetric observables, i.e. copolar reflectivity and differential reflectivity, and it is finally applied to data coming from radar sites located in Gattatico and S. Pietro Capofiume in North Italy. The final purpose is to show qualitative accuracy improvements with respect to the use of a set of ten bidimensional MBFs, previously adopted and well suited to S-band data but not to C-band data.

Marzano, F. S.; Scaranari, D.; Celano, M.; Alberoni, P. P.; Vulpiani, G.; Montopoli, M.

2006-02-01

323

A comparison of NEXRAD WSR-88D radar estimates of rain accumulation with gauge measurements for high- and low-reflectivity horizontal gradient precipitation events.  

SciTech Connect

Radar-estimated rainfall amounts from the NEXRAD Weather Surveillance Radar precipitation accumulation algorithm were compared with measurements from numerous rain gauges (1639 radar versus gauge comparisons). Storm total rain accumulations from 43 rain events from 10 radar sites were analyzed. These rain events were stratified into two precipitation types: (1) high-reflectivity horizontal gradient storms and (2) low-reflectivity horizontal gradient events. Overall, the radar slightly overestimated rainfall accumulations for high-reflectivity gradient cases and significantly underestimated accumulations for low-reflectivity gradient cases. Varying degrees of range effects were observed for these two types of precipitation. For high-reflectivity gradient cases, the radar underestimated rainfall at the nearest ranges, overestimated at the middle ranges, and had fairly close agreements at the farthest ranges. A much stronger range bias was evident for low-reflectivity gradient cases. The radar underestimated rainfall by at least a factor of 2 in the nearest and farthest ranges, and to a somewhat lesser extent at midranges.

Klazura, G. E.; Thomale, J. M.; Kelly, D. S.; Jendrowski, P.; Environmental Research; Univ. of Oklahoma; National Weather Service

1999-11-01

324

Recent findings with rainfall monitoring by cellular communication systems  

NASA Astrophysics Data System (ADS)

We will demonstrate how 19 rainfall storms from recent two full winter seasons over south Israel are analyzed with high-resolution (1 minute time interval) data from a cellular network. New insight into the hydrological applications from this new source on rainfall, including flood warning, is given by this source of data and compared to classical methods based on rain-gauges and radar. One case of flooding in 2008 over the Judea Desert, central Israel, will be analyzed. Global spread of wireless networks brings a great opportunity for their use in environmental studies. Weather, atmospheric conditions and constituents cause propagation impairments on radio links. As such, wireless communication systems provide built-in monitoring capabilities, and can be considered as a widespread distributed, high-resolution atmospheric observation network, operating in real time, with minimum supervision and with almost no additional cost. Here, we demonstrate how standard measurements of the received signal level, made in a cellular network, provide reliable measurements for surface rainfall. We compare the estimated rainfall intensity with the radar and rain gauge measurements.

Alpert, P.; Rayitsfeld, A.; David, N.; Goldshtein, O.; Messer, H.; Zinevich, A.

2009-04-01

325

Microphysical cross validation of spaceborne radar and ground polarimetric radar  

Microsoft Academic Search

Ground-based polarimetric radar observations along the beam path of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), matched in resolution volume and aligned to PR measurements, are used to estimate the parameters of a gamma raindrop size distribution (RSD) model along the radar beam in the presence of rain. The PR operates at 13.8 GHz, and its signal returns

V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

2003-01-01

326

New software methods in radar ornithology using WSR-88D weather data and potential application to monitoring effects of climate change on bird migration  

USGS Publications Warehouse

Radar ornithology has provided tools for studying the movement of birds, especially related to migration. Researchers have presented qualitative evidence suggesting that birds, or at least migration events, can be identified using large broad scale radars such as the WSR-88D used in the NEXRAD weather surveillance system. This is potentially a boon for ornithologists because such data cover a large portion of the United States, are constantly being produced, are freely available, and have been archived since the early 1990s. A major obstacle to this research, however, has been that identifying birds in NEXRAD data has required a trained technician to manually inspect a graphically rendered radar sweep. A single site completes one volume scan every five to ten minutes, producing over 52,000 volume scans in one year. This is an immense amount of data, and manual classification is infeasible. We have developed a system that identifies biological echoes using machine learning techniques. This approach begins with training data using scans that have been classified by experts, or uses bird data collected in the field. The data are preprocessed to ensure quality and to emphasize relevant features. A classifier is then trained using this data and cross validation is used to measure performance. We compared neural networks, naive Bayes, and k-nearest neighbor classifiers. Empirical evidence is provided showing that this system can achieve classification accuracies in the 80th to 90th percentile. We propose to apply these methods to studying bird migration phenology and how it is affected by climate variability and change over multiple temporal scales.

Mead, Reginald; Paxton, John; Sojda, Richard S.

2010-01-01

327

Areal rainfall estimates using differential phase  

Microsoft Academic Search

Radar polarimetric methods for rainfall measurements have received increasing attention in recent years. The one based on the estimate of specific differential phase KDP uses the relation: R=aKDPb where R is rain rate. This method has several advantages compared to the conventional one which utilizes radar reflectivity factor Z. Differential phase is immune to radar miscalibration, microwave attenuation, partial beam

Alexander Ryzhkov; Dusan Zrnic

1998-01-01

328

Short period forecasting of catchment-scale precipitation. Part II: a water-balance storm model for short-term rainfall and flood forecasting  

NASA Astrophysics Data System (ADS)

A simple two-dimensional rainfall model, based on advection and conservation of mass in a vertical cloud column, is investigated for use in short-term rainfall and flood forecasting at the catchment scale under UK conditions. The model is capable of assimilating weather radar, satellite infra-red and surface weather observations, together with forecasts from a mesoscale numerical weather prediction model, to obtain frequently updated forecasts of rainfall fields. Such data assimilation helps compensate for the simplified model dynamics and, taken together, provides a practical real-time forecasting scheme for catchment scale applications. Various ways are explored for using information from a numerical weather prediction model (16.8 km grid) within the higher resolution model (5 km grid). A number of model variants is considered, ranging from simple persistence and advection methods used as a baseline, to different forms of the dynamic rainfall model. Model performance is assessed using data from the Wardon Hill radar in Dorset for two convective events, on 10 June 1993 and 16 July 1995, when thunderstorms occurred over southern Britain. The results show that (i) a simple advection-type forecast may be improved upon by using multiscan radar data in place of data from the lowest scan, and (ii) advected, steady-state predictions from the dynamic model, using "inferred updraughts", provides the best performance overall. Updraught velocity is inferred at the forecast origin from the last two radar fields, using the mass-balance equation and associated data and is held constant over the forecast period. This inference model proves superior to the buoyancy parameterisation of updraught employed in the original formulation. A selection of the different rainfall forecasts is used as input to a catchment flow forecasting model, the IH PDM (Probability Distributed Moisture) model, to assess their effect on flow forecast accuracy for the 135 km2 Brue catchment in Somerset.

Bell, V. A.; Moore, R. J.

329

Multiple-Scattering Formulation of Pulsed Beam Waves in Hydrometeors and Its Application to Millimeter-Wave Weather Radar  

Microsoft Academic Search

This letter deals with the backscattering of millimeter pulsed beam waves from hydrometeors. A new approach is presented for a solution of time-dependent three-dimensional vector radiative transfer equation for the Stokes vectors to study the multiple-scattering effects of beam waves on radar echoes. General solutions for beam waves are derived in an integral form without any approximation. They are given

Shigeo Ito; Satoru Kobayashi; Tomohiro Oguchi

2007-01-01

330

A study of how aerosols affect low-level clouds over the Nordic Countries using MODIS, ground-based, ECMWF and weather radar data.  

NASA Astrophysics Data System (ADS)

Several types of data have been combined to investigate how aerosol particles and meteorological parameters affect microphysical, radiative and precipitation properties of low-level clouds over Sweden and Finland. The cloud data was obtained from the MODIS (Moderate Resolution Imaging Spectrometer) instrument on board the Terra and Aqua satellites. The satellite scenes were screened manually for low-level clouds in limited areas around two background aerosol measurement stations. One of the stations, Vavihill, is located in Southern Sweden (56.01° N 13.9° E) and 9 years of number size distribution data from a DMPS (Differential Mobility Particle Sizer) instrument placed there was used in this study. Hyytiälä, the other station, is situated in central Finland (61.51° N 24.17° E) and 10 years of DMPS from this station data were analysed. Furthermore, modelled meteorological parameters from the European Centre for Medium-Range Forecasts (ECMWF) as well as ground-based precipitation measurements from the SMHI (Swedish Meteorological and Hydrological Institute) and from FMI (Finish Meteorological Institute) have been used in the study. Also, to be able to estimate precipitation rates in the clouds, weather radar data obtained in the BALTEX (Baltic Sea Experiment) project were utilized. The study includes 229 cases from the Vavihill region and 313 cases from the Hyytiälä area. The results from both regions show that aerosol concentrations measured at the ground-based stations have significant negative correlations with the effective radius (re) of the low-level clouds. The correlation is stronger when the re at 3.7?m is used rather than that at 2.1?m and the highest correlations are obtained when aerosol number concentrations of particles with sizes above 180 nm are used. The correlations between cloud optical thickness (COT) and aerosol number concentrations are on the other hand are positive but lower than for the re. Also, the COT correlate better with particles at larger size than the re and the strongest correlation occur at aerosol number concentrations of particles above 500 nm. However, the relative humidity at 1000 hPa is the variable that has the strongest correlation with COT. Neither the ground-based precipitation data nor the weather radar data show any significant correlations with the aerosol number concentrations at both stations. Nevertheless, there is a significant but low positive correlation between the re and the strength of the radar reflectivity factor. Hence, the first indirect aerosol effect can be detected in this dataset but not the second indirect aerosol effect.

Sporre, M. K.; Swietlicki, E.; Glantz, P.; Kulmala, M.

2012-04-01

331

Impacts of polarimetric radar observations on hydrologic simulation  

NASA Astrophysics Data System (ADS)

This study presents an analysis of hydrologic simulations performed for a dataset of several rainfall-runoff events, including a 100-year event, that were captured by the polarimetric prototype of the WSR-88D radar, KOUN. The focus basin is the heavily instrumented Ft. Cobb basin in Oklahoma which features a Micronet, a network of 15 hydrometeorological stations, and four US Geological Survey stream gauges. The high-density rain gauge network was used to evaluate the polarimetric rainfall algorithms. We also set up and rigorously calibrated the National Weather Service Office of Hydrologic Development's 19-parameter distributed hydrologic model over a three-year period. Benchmark simulations were produced using inputs from the rain gauge-only product that was used for calibration. The hydrologic model was then forced with rainfall using the standard WSR-88D reflectivity-to-rainfall (Z-R) relation as well as recently proposed rainfall algorithms based on polarimetric variables. Ultimately, this study aims to answer: "What will polarimetric radar do for flash flood prediction?"

Gourley, Jonathan; Flamig, Zachary; Hong, Yang; Schuur, Terry; Giangrande, Scott; Vrugt, Jasper

2010-05-01

332

Probabilistic rainfall warning system with an interactive user interface  

NASA Astrophysics Data System (ADS)

A real time 24/7 automatic alert system is in operational use at the Finnish Meteorological Institute (FMI). It consists of gridded forecasts of the exceedance probabilities of rainfall class thresholds in the continuous lead time range of 1 hour to 5 days. Nowcasting up to six hours applies ensemble member extrapolations of weather radar measurements. With 2.8 GHz processors using 8 threads it takes about 20 seconds to generate 51 radar based ensemble members in a grid of 760 x 1226 points. Nowcasting exploits also lightning density and satellite based pseudo rainfall estimates. The latter ones utilize convective rain rate (CRR) estimate from Meteosat Second Generation. The extrapolation technique applies atmospheric motion vectors (AMV) originally developed for upper wind estimation with satellite images. Exceedance probabilities of four rainfall accumulation categories are computed for the future 1 h and 6 h periods and they are updated every 15 minutes. For longer forecasts exceedance probabilities are calculated for future 6 and 24 h periods during the next 4 days. From approximately 1 hour to 2 days Poor man's Ensemble Prediction System (PEPS) is used applying e.g. the high resolution short range Numerical Weather Prediction models HIRLAM and AROME. The longest forecasts apply EPS data from the European Centre for Medium Range Weather Forecasts (ECMWF). The blending of the ensemble sets from the various forecast sources is performed applying mixing of accumulations with equal exceedance probabilities. The blending system contains a real time adaptive estimator of the predictability of radar based extrapolations. The uncompressed output data are written to file for each member, having total size of 10 GB. Ensemble data from other sources (satellite, lightning, NWP) are converted to the same geometry as the radar data and blended as was explained above. A verification system utilizing telemetering rain gauges has been established. Alert dissemination e.g. for citizens and professional end users applies SMS messages and, in near future, smartphone maps. The present interactive user interface facilitates free selection of alert sites and two warning thresholds (any rain, heavy rain) at any location in Finland. The pilot service was tested by 1000-3000 users during summers 2010 and 2012. As an example of dedicated end-user services gridded exceedance scenarios (of probabilities 5 %, 50 % and 90 %) of hourly rainfall accumulations for the next 3 hours have been utilized as an online input data for the influent model at the Greater Helsinki Wastewater Treatment Plant.

Koistinen, Jarmo; Hohti, Harri; Kauhanen, Janne; Kilpinen, Juha; Kurki, Vesa; Lauri, Tuomo; Nurmi, Pertti; Rossi, Pekka; Jokelainen, Miikka; Heinonen, Mari; Fred, Tommi; Moisseev, Dmitri; Mäkelä, Antti

2013-04-01

333

Automatic morphing using image registration: Application to continuous tracking of radar reflectivity and rain fields  

NASA Astrophysics Data System (ADS)

Rainfall is one of the most important natural phenomenon that influences human life. Accurate rainfall estimation and prediction are crucial for flood forecasting, flood control, climate diagnostics, and water resource management. Rain data may be collected from numerous sources. Conventional rain gauge networks or meteorological radars provide continuous coverage in time. Satellite observations provide snap-shots of precipitation fields at poor temporal resolution. While a number of spaceborne platforms have been deployed for rain observation, the development of continuous space/time rainfall remains a major challenge. This dissertation seeks alternative techniques to automatically generate continuous data streams of rainfall data from sparse or intermittent observations. In order to avoid human intervention in the process, an automatic procedure is needed for real-time operations. For this purpose, Automatic Morphing Using Image Registration (AMIR) model is developed by integrating automatic image registration and image morphing algorithm. The new AMIR technique uses automatic image registration as the basis for finding control points for the morphing process. In the study of data assimilation for weather forecasting, there is a need to generate continuous streams of rainfall data to alleviate the so-called "spin up" problem, or the inability to provide short-term forecasts [Road90]. The proposed algorithm has been tested using remote sensing images from Next Generation Weather Radars (NEXRAD) and Tropical Rainfall Measuring Mission (TRMM). Three cases of rainfall data have been used. These include the passage of a storm in Florida, hurricane Floyd, and scattered rain in the southwestern of the United States for the same period using NEXRAD radar data as surrogate for spaceborne observations. These cases have drastically different spatial and temporal characteristics and hence provide tests on the applicability of the AMIR method. Comparative experimental results have shown that AMIR advance the current state of the art as it is comparable to manual morphing and outperforms automatic morphing without control points proposed in literature.

Vongsaard, Jearanai

334

Introduction to Weather  

NSDL National Science Digital Library

This resource provides an overview of weather, the day-to-day changes in temperature, air pressure, moisture, wind, cloudiness, rainfall and sunshine. Links embedded in the text provide access to descriptions of cloud types and to information on weather hazards such as fog, hurricanes, thunderstorms, and tornadoes. Other topics include meteorology, weather measurements, and weather mapping. Materials are also provided on the water cycle and its elements, such as evaporation, uplift and cooling of air, dew point, condensation, and precipitation.

2010-01-01

335

A novel radar-based analysis of urban-induced convergence: A possible explanation of the 1 downwind urban rainfall anomaly 2  

Microsoft Academic Search

We discuss a radar motion vector (RMV) tracking approach to investigate the winds and 14 composite reflectivity patterns for urban storms, and for the first time provide radar-derived 15 evidence of the existence of an urban convergence zone. Synthesis of 53 different storms 16 crossing the Indianapolis urban area reveals spatial anomalies in the storm motion around the 17 urban

C. M. Kishtawal; Dev Niyogi; Lei Ming; J. Marshall Shepherd; Jared K. Entin

336

Unisys Weather  

NSDL National Science Digital Library

The Unisys weather website offers a host of weather analyses and forecasts. In the Analyses link, visitors can find satellite images as well as surface, upper air, and radar images. Visitors can learn the intricacies of Unisys's many forecast models such as the Nested Grid Model (NGM), Aviation Model, and the Rapid Update Cycle (RUC) Model. Users can find archived hurricane data for the Atlantic, the Eastern Pacific, and the Western Pacific. The site also furnishes archived surface maps, infrared satellite images, upper air charts, and sea surface temperature (SST) plots.

337

Space Weather FX  

NSDL National Science Digital Library

Space Weather FX is a vodcast (video podcast) series that explores the science of space weather and how it can impact our every day lives. Episodes include Space Weather and its Effects, Connecting the Sun and Earth, When Space Weather Attacks, Stratospheric Sudden Warming, A Tour of Haystack's Radars, GPS and Space Weather, It Came from the Sun, and The Big Picture. The site also contain links to space weather information and educational materials. The episodes will run on one of four free video players.

338

Tomography applied to radiobase network for real time estimation of the rainfall rate fields  

NASA Astrophysics Data System (ADS)

Recently, we proposed a novel remote sensing method for rainfall rate estimation in real time by means of tomographic processing applied to power attenuation measurements made across the microwave links defined by radiobase station networks for mobile communication systems. In this paper we analyze the results of a new tomographic algorithm that has been specifically developed for the typical topology of the urban radiobase station networks. Such algorithm has been tested on simulated specific attenuation (K) maps based on true polarimetric weather radar data. We considered 18, 23, and 38 GHz for the carrier frequencies of the radiobase network and the weather data gathered by the POLAR 55C polarimetric radar located in Rome.

Cuccoli, F.; Baldini, L.; Facheris, L.; Gori, S.; Gorgucci, E.

2013-01-01

339

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

340

Quantitative rainfall metrics for comparing volumetric rainfall retrievals to fine scale models  

NASA Astrophysics Data System (ADS)

Precipitation processes play a significant role in the energy balance of convective systems for example, through latent heating and evaporative cooling. Heavy precipitation "cores" can also be a proxy for vigorous convection and vertical motions. However, comparisons between rainfall rate retrievals from volumetric remote sensors with forecast rain fields from high-resolution numerical weather prediction simulations are complicated by differences in the location and timing of storm morphological features. This presentation will outline a series of metrics for diagnosing the spatial variability and statistical properties of precipitation maps produced both from models and retrievals. We include existing metrics such as Contoured by Frequency Altitude Diagrams (Yuter and Houze 1995) and Statistical Coverage Products (May and Lane 2009) and propose new metrics based on morphology, cell and feature based statistics. Work presented focuses on observations from the ARM Southern Great Plains radar network consisting of three agile X-Band radar systems with a very dense coverage pattern and a C Band system providing site wide coverage. By combining multiple sensors resolutions of 250m2 can be achieved, allowing improved characterization of fine-scale features. Analyses compare data collected during the Midlattitude Continental Convective Clouds Experiment (MC3E) with simulations of observed systems using the NASA Unified Weather Research and Forecasting model. May, P. T., and T. P. Lane, 2009: A method for using weather radar data to test cloud resolving models. Meteorological Applications, 16, 425-425, doi:10.1002/met.150, 10.1002/met.150. Yuter, S. E., and R. A. Houze, 1995: Three-Dimensional Kinematic and Microphysical Evolution of Florida Cumulonimbus. Part II: Frequency Distributions of Vertical Velocity, Reflectivity, and Differential Reflectivity. Mon. Wea. Rev., 123, 1941-1963, doi:10.1175/1520-0493(1995)123<1941:TDKAME>2.0.CO;2.

Collis, Scott; Tao, Wei-Kuo; Giangrande, Scott; Fridlind, Ann; Theisen, Adam; Jensen, Michael

2013-04-01

341

Movement and Predictability of Radar Echoes.  

National Technical Information Service (NTIS)

Quantitative weather radar data collected by the WSR-57 radars at Atlantic City, N. J. and Norman, Okla. have been analyzed with high speed computers to investigate the movement and predictability of weather radar echoes. The location of the maximum cross...

J. W. Wilson

1966-01-01

342

Advances in Radar Techniques  

NASA Astrophysics Data System (ADS)

Most of the clutter received by L, S, C, X, and Ku band radars obeys a Weibull ditribution. To suppress such Weibull-distributed sea and weather clutter, Weibull CFAR techniques are applied to data taken by an X-band radar using computer in real time. The results show the usefulness of Weibull CFAR.

Sekine, Matsuo

343

Coupling X-band dual-polarized mini-radars and hydro-meteorological forecast models: the HYDRORAD project  

NASA Astrophysics Data System (ADS)

Hydro-meteorological hazards like convective outbreaks leading to torrential rain and floods are among the most critical environmental issues world-wide. In that context weather radar observations have proven to be very useful in providing information on the spatial distribution of rainfall that can support early warning of floods. However, quantitative precipitation estimation by radar is subjected to many limitations and uncertainties. The use of dual-polarization at high frequency (i.e. X-band) has proven particularly useful for mitigating some of the limitation of operational systems, by exploiting the benefit of easiness to transport and deploy and the high spatial and temporal resolution achievable at small antenna sizes. New developments on X-band dual-polarization technology in recent years have received the interest of scientific and operational communities in these systems. New enterprises are focusing on the advancement of cost-efficient mini-radar network technology, based on high-frequency (mainly X-band) and low-power weather radar systems for weather monitoring and hydro-meteorological forecasting. Within the above context, the main objective of the HYDRORAD project was the development of an innovative integrated decision support tool for weather monitoring and hydro-meteorological applications. The integrated system tool is based on a polarimetric X-band mini-radar network which is the core of the decision support tool, a novel radar products generator and a hydro-meteorological forecast modelling system that ingests mini-radar rainfall products to forecast precipitation and floods. The radar products generator includes algorithms for attenuation correction, hydrometeor classification, a vertical profile reflectivity correction, a new polarimetric rainfall estimators developed for mini-radar observations, and short-term nowcasting of convective cells. The hydro-meteorological modelling system includes the Mesoscale Model 5 (MM5) and the Army Corps of Engineers Hydrologic Engineering Center hydrologic and hydraulic modelling chain. The characteristics of this tool make it ideal to support flood monitoring and forecasting within urban environment and small-scale basins. Preliminary results, carried out during a field campaign in Moldova, showed that the mini-radar based hydro-meteorological forecasting system can constitute a suitable solution for local flood warning and civil flood protection applications.

Picciotti, E.; Marzano, F. S.; Anagnostou, E. N.; Kalogiros, J.; Fessas, Y.; Volpi, A.; Cazac, V.; Pace, R.; Cinque, G.; Bernardini, L.; De Sanctis, K.; Di Fabio, S.; Montopoli, M.; Anagnostou, M. N.; Telleschi, A.; Dimitriou, E.; Stella, J.

2013-05-01

344

Quantitative precipitation climatology over the Himalayas by using Precipitation Radar on Tropical Rainfall Measuring Mission (TRMM) and a dense network of rain-gauges  

NASA Astrophysics Data System (ADS)

Quantified grid observation data at a reasonable resolution are indispensable for environmental monitoring as well as for predicting future change of mountain environment. However quantified datasets have not been available for the Himalayan region. Hence we evaluate climatological precipitation data around the Himalayas by using Precipitation Radar (PR) data acquired by the Tropical Rainfall Measuring Mission (TRMM) over 10 years of observation. To validate and adjust these patterns, we used a dense network of rain gauges collected by the Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE Water Resources) project (http://www.chikyu.ac.jp/precip/). We used more than 2600 stations which have more than 10-year monthly precipitation over the Himalayan region (75E-105E, 20-36N) including country data of Nepal, Bangladesh, Bhutan, Pakistan, India, Myanmar, and China. The region we studied is so topographically complicated that horizontal patterns are not uniform. Therefore, every path data of PR2A25 (near-surface rain) was averaged in a 0.05-degree grid and a 10-year monthly average was computed (hereafter we call PR). On the other hand, for rain-gauge, we first computed cell averages if each 0.05-degree grid cell has 10 years observation or more. Here we refer to the 0.05-degree rain-gauge climatology data as RG data. On the basis of comparisons between the RG and PR composite values, we defined the parameters of the regressions to correct the monthly climatology value based on the rain gauge observations. Compared with the RG, the PR systematically underestimated precipitation by 28-38% in summer (July-September). Significant correlation between TRMM/PR and rain-gauge data was found for all months, but the correlation is relatively low in winter. The relationship is investigated for different elevation zones, and the PR was found to underestimate RG data in most zones, except for certain zones in February (250-1000m), March (0-1000m), and April (0-1500m). We depicted the adjusted precipitation climatology based on the TRMM/PR composites. The monthly composite patterns of the TRMM/PR for the 10 years show that the southern foothills of the Himalayas always have a clear rain band, with clear dry areas north of the Himalayas. The double rain bands along the Himalayas are clearly shown, and a rain band with a high maximum appeared in the area of Bhutan (around 27°N, 90°) in summer monsoon season. Little precipitation is observed on the Himalayas or Tibet at elevations higher than 4800 m. In the summer monsoon season, precipitation over the Tibetan Plateau increases, especially in the east. In the winter season (November-March) in particular, more precipitation is seen west of the Himalayas (north India) and very dry areas are observed to the north. Improvement of the APHRODITE's daily grid precipitation analysis by using this climatology will be shown.

Yatagai, A.

2010-09-01

345

Using Satellite Rainfall for Simulation of Flash Floods in Mountainous Basins  

NASA Astrophysics Data System (ADS)

Effective flash flood warning procedures are usually hampered by observational limitations of precipitation over mountainous basins where flash floods occur. Satellite rainfall estimates are available over complex terrain regions offering a potentially viable solution to the observational coverage problem. However, satellite estimates of heavy rainfall rates are associated with significant biases and random errors that non-linearly propagate in hydrologic modeling imposing severe limitations on the use of these products in flood forecasting. In this study we investigate the use of three quasi-global and near-real-time high-resolution satellite-rainfall products (3B42, PERSIANN, CMORPH) for simulating flash floods over complex terrain basins. The study uses major flash flood events on medium size mountainous basins (600-1500 km2) in Northern Italian Alps. Comparison of satellite-rainfall with rainfall derived from gauge-calibrated weather radar estimates showed that although satellite products suffer from large biases they could represent the temporal variability of basin-averaged precipitation. Propagation of satellite-rainfall through a hydrologic model revealed that systematic error in rainfall was severely magnified when transformed to error in runoff (especially under dry initial soil conditions). Simulation hydrographs became meaningful after adjusting the satellite rainfall for underestimation due to retrieval bias and resolution effects determined based on high-resolution cloud-resolving storm simulations. Overall, this study highlights the use of high-resolution NWP analysis for improving satellite-rainfall retrieval to allow a more appropriate use of satellite-rainfall products in flash-flood applications of complex terrain basins.

Anagnostou, Emmanouil; Nikolopoulos, Efthymios; Bartsotas, Nikolaos; Solomos, Stavros; Kallos, George

2013-04-01

346

An Estimation-Based Precipitation Retrieval Algorithm for Attenuating Radars  

Microsoft Academic Search

A new method for retrieving rainfall profiles from a spaceborne radar is introduced. As a result of the frequencies necessary in spaceborne radar applications, attenuation by both rainfall and liquid cloud particles is nonnegligible and must be accurately accounted for before quantitative rainfall estimates can be made. The proposed method is based on the minimization of a cost function that

Tristan S. L'Ecuyer; Graeme L. Stephens

2002-01-01

347

Towards Near Real-time Convective Rainfall Observations over Kenya  

NASA Astrophysics Data System (ADS)

The existing meteorological infrastructure in Kenya is poorly suited for the countrywide real-time monitoring of precipitation. Rainfall radar is not available, and the existing network of rain gauges is sparse and challenging to maintain. This severely restricts Kenya's capacity to warn for, and respond to, weather related emergencies. Furthermore, the lack of accurate rainfall observations severely limits Kenya's climate change adaptation capabilities. Over the past decade, the mobile telephone network in Kenya has expanded rapidly. This network makes extensive use of terrestrial microwave (MW) links, received signal level (RSL) data from which can be used for the calculation of rainfall intensities. We present a novel method for the near-real time observation of convective rainfall over Kenya, based on the combined use of MW RSL data and Meteosat Second Generation (MSG) satellite data. In this study, the variable density rainfall information derived from several MW links is scaled up using MSG data to provide full rainfall information coverage for the region surrounding the links. Combining MSG data and MW link derived rainfall data for several adjacent MW links makes it possible to make the distinction between wet and dry pixels. This allows the disaggregation of the MW link derived rainfall intensities. With the distinction between wet and dry pixels made, and the MW derived rainfall intensities disaggregated, these data can then be used to develop instantaneous empirical relationships linking rainfall intensities to cloud physical properties. These relationships are then used to calculate rainfall intensities for the MSG scene. Since both the MSG and the MW data are available at the same temporal resolution, unique empirical coefficients can be determined for each interval. This approach ensures that changes in convective conditions from one interval to the next are taken into account. Initial results from a pilot study, which took place from November 2012 until January 2013, are presented. The work has been carried out in close cooperation with mobile telephone operator Safaricom, using RSL data from 15 microwave links in rain prone areas in Western Kenya (out of a total of 3000 MW links operated by Safaricom in Kenya). The data supplied by Safaricom consist of the mean, minimum and maximum RSL for each MW link over a 15 minute interval. For this pilot study, use has been made of the MSG Cloud Top Temperature data product from the Royal Dutch Meteorological Institute's MSG Cloud Physical Properties database (http://msgcpp.knmi.nl/).

Hoedjes, Joost; Said, Mohammed; Becht, Robert; Kifugo, Shem; Kooiman, André; Limo, Agnes; Maathuis, Ben; Moore, Ian; Mumo, Mark; Nduhiu Mathenge, Joseph; Su, Bob; Wright, Iain

2013-04-01

348

Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007  

NASA Astrophysics Data System (ADS)

During a weather front that passed over large parts of Slovenia on 18.9.2007, extreme rainfall events were triggered causing several severe flash floods with six casualties. Out of 210 municipalities in Slovenia, 60 were reporting flood damages, and the total economic flood damage was later estimated at close to 200 million Euro; highest damage was claimed by Železniki municipality in NW Slovenia. The main purpose of the study presented in this paper was to put together available meteorological and hydrological data in order to get better insight into temporal and spatial dynamics and variability of the flash flood event along the Sel\\vska Sora River flowing through the town of Železniki. The weather forecast by the Environmental Agency of the Republic of Slovenia (ARSO) lead to early warning of floodings but has underestimated rainfall amounts by a factor of 2. Also meteorological radar underestimated ground rainfall as much as by 50%. During that day, in many rainfall gauging stations operated by ARSO in the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm in 24 h or 157 mm in 2 h. Some of the measured rainfall amounts were the highest registered amounts in Slovenia so far. Statistical analysis using Gumble distribution was performed and rainfall return periods were estimated. When assessing rainfall return periods, a question of the sampling error as a consequence of short rainfall records used was raised. Furthermore, measured rainfall data were used to reconstruct hydrographs on selected water stations along the Sel\\vska Sora River. The cumulative areal precipitation for the Sel\\vska Sora River catchment upstream of Železniki amounted to 219 mm, while the modeled effective precipitation used to simulate the hydrograph peak was only 57 mm. The modeled direct runoff coefficient therefore amounts to 0.26. Surprisingly low value is mainly caused by the applied unit hydrograph method that seeks to meet the peak discharge rather than hydrograph volume. However, the spatial distribution of the rainfall in the area was highly variable and present spatial positioning of rain gauges is obviously inadequate for proper representation of the actual spatial amount of rainfall. The study confirmed that post-flood investigation should focus on discharges and hydrological response of the catchment rather than simply analyzing statistical characteristics of rainfall.

Rusjan, S.; Kobold, M.; Mikoš, M.

2009-06-01

349

Radar Wind Profilers in the Colorado Network.  

National Technical Information Service (NTIS)

Radar systems used to measure vertical profiles of the horizontal wind in nearly all weather conditions can use frequencies between about 40 and 1000 MHz. This report describes three radar systems that measure wind profiles continuously and automatically....

R. G. Strauch D. A. Merritt K. P. Moran

1985-01-01

350

46 CFR 121.404 - Radars.  

Code of Federal Regulations, 2012 CFR

...OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS VESSEL CONTROL AND MISCELLANEOUS SYSTEMS AND EQUIPMENT Navigation Equipment...radar is not necessary due to the vessel's route and local weather conditions. (c) The radar and its installation must...

2012-10-01

351

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.

352

Remotely-Sensed Rainfall for the Wettest Season in Oklahoma on Record  

NASA Astrophysics Data System (ADS)

In the summer of 2007 Oklahoma experienced the wettest June on record, Oklahoma City had 20 consecutive days of reported rainfall (also a record), and damaging flash floods occurred on 15 days. This study analyzes the spatial patterns, temporal variability, and magnitudes of remotely-sensed rainfall from TRMM satellite, PERSIANN-CCS, and the operational rainfall product in the US National Weather Service (NWS) that relies on radar data with adjustments from rain gauges and human quality control. Conclusions drawn from this part of the study will help guide future steps toward integrated, multisensor precipitation estimation as applied to a season of extreme rainfall. The second part of the study applies the rainfall estimates under evaluation to an extreme flash flood case over the heavily instrumented Ft. Cobb basin in Oklahoma. Discharge is simulated and compared to observed streamflow on three subbasins using the NWS's distributed hydrologic model. Results will help determine if satellite-based rainfall estimates can be used, given proper downscaling, as inputs to hydrologic prediction models for extreme, small-scale hydrometeorological events.

Flamig, Z.; Gourley, J.; Hong, Y.; Li, L.

2009-05-01

353

Areal Rainfall Estimates Using Differential Phase  

Microsoft Academic Search

A radar polarimetric method for areal rainfall estimation is examined. In contrast to the polarimetric algorithm based on specific differential phase KDP, the proposed method does not require rain-rate estimation from KDP inside the area of interest, but it utilizes only values of total differential phase DP on the areal contour. Even if the radar reflectivity and differential phase data

Alexander Ryzhkov; Dusan Zrni; Richard Fulton

2000-01-01

354

Precipitation estimation and forecasting using radar and rain gage measurements with artificial neural networks  

NASA Astrophysics Data System (ADS)

Quantitative precipitation estimation and forecasting continue to be critical components of the weather research programs. The objective of this dissertation is twofold: First, to propose a method that fuses rainfall measurements from rain gages and radar. Second, to design a technique that produces real-time rainfall forecasts for the next hour. Cokriging is perhaps the most widely used method to fuse measurements from two sensors, for example, radar and rain gages. Here an alternative fusion methodology, based on recent developments in Artificial Neural Networks (ANNs) is presented. ANNs are nonlinear estimators and thus have a distinct advantage over traditional statistical methods. Intercomparison of rainfall estimation, using cokriging and ANN methods, suggests that ANNs provide a more attractive and robust fusion from radar and rain gages for several storms from Oklahoma. It is shown that simply nowcasting the fused estimates gives better forecasts than the traditional nowcasting with radar data. Moreover, the rainfall field at the next hour is predicted with a methodology that is based on radial-basis ANNs. The advantage of this method is that it provides a framework for the automated segmentation of the rainfall field in rainfall clusters that have their own advection vectors. Each cluster is shifted individually for the prediction step. Thus, the method accounts for nonhomogeneous advection conditions. The results show that this method has the capability to generate improved predictions compared to nowcasting. It appears that its full strength will be realized if a data set with a temporal resolution finer than hourly is used. In summary, an integrated ANN approach has been produced that estimates rainfall from two sensors and produces a forecast. In the appendix I also include a study on the nature of long-range rainfall and streamflow correlations, using a method called Detrended Fluctuation Analysis. The findings show the existence of power-law correlations in both variables. Moreover, it is shown that what controls the correlation structure is not the actual rainfall values, but the pattern of alternating wet and dry spells. The employed method also highlights the dampening effect of the soil in the transformation of rainfall to streamflow.

Matsoukas, Christos

2000-11-01

355

Rainfall Runoff  

NSDL National Science Digital Library

This is a resource from the Geological Survey of the United States dealing with rainfall and runoff. The resource provides a description of runoff and the factors that impact the amount of rainfall runoff for a particular area.

2008-04-24

356

Lightning, radar reflectivity, infrared brightness temperature, and surface rainfall during the 2–4 July 2004 severe convective system over Taiwan area  

Microsoft Academic Search

On 2–4 July 2004, unusually severe convective systems developed over Taiwan area, following the passage of Typhoon Mindulle (10W, T0407). During the lifetime of these storms, total lightning was detected by the TPC SAFIR total lightning detection system, infrared cloud-top temperatures were measured by the NOAA GOES-9 satellite, radar reflectivity was observed by the CWB Doppler network, and hourly surface

Kuo-Ying Wang; Shun-An Liao

2006-01-01

357

Lightning, radar reflectivity, infrared brightness temperature, and surface rainfall during the 2-4 July 2004 severe convective system over Taiwan area  

Microsoft Academic Search

On 2-4 July 2004, unusually severe convective systems developed over Taiwan area, following the passage of Typhoon Mindulle (10W, T0407). During the lifetime of these storms, total lightning was detected by the TPC SAFIR total lightning detection system, infrared cloud-top temperatures were measured by the NOAA GOES-9 satellite, radar reflectivity was observed by the CWB Doppler network, and hourly surface

Kuo-Ying Wang; Shun-An Liao

2006-01-01

358

Where to measure point rainfall during extreme flash flood events in mountainous catchments?  

NASA Astrophysics Data System (ADS)

Despite the availability of weather radar data at high spatial (1 km^2) and temporal (5-15 min) resolution, ground-based rain gauges are still needed to accurately estimate storm rainfall input to catchments during flash flood events. This is especially true in mountainous catchments where estimating storm depth and intensity from radar data is more challenging than in flat terrain. Given economical limitations on the number of rain gauges, a long-standing problem in catchment hydrology is where to put the (limited amount of) rain gauges to best capture both storm rainfall depth and temporal variability of storm intensity during extreme events. This study addresses the question whether it is possible to predict the best locations for rain gauge installation given a basin's topography and dominant storm tracks. A network of 40 tipping bucket rain gauges was deployed in the Sabino Canyon catchment near Tucson, AZ, during the summer monsoon season of 2006. An extreme, multi-day rainfall event during 27-31 July 2006 caused record flooding and an unprecedented series of slope failures and debris flows in the Santa Catalina Mountains. Geostatistics (kriging with external drift, KED) was used to combine the tipping bucket rain gauge observations with NEXRAD weather radar to create rasterized rainfall maps with high spatial (1 km^2) and temporal (15 min) resolution over the entire multi-day rainfall event. We use these KED rainfall maps to determine the optimized locations for an installation of 1 up to 4 rain gauges considering all possible subsets of 1 to 4 grid cells over the entire rainfall event. Our optimization method minimizes both the residual percent bias and the coefficient of correlation between the mean areal rainfall obtained using the KED rainfall maps and mean rainfall determined using each subset. This method was applied to the entire record of rainfall observations to identify networks consisting of 1 to 4 rain gauges which represent the ‘best' compromise between the two criteria. To determine the effect of the length of record of observations on the selected rain gauge networks, ‘best' compromise networks were identified using the same method treating each single rainfall event (seven in total) independently. A semi-arid rainfall-runoff model (KINEROS2) was then used to evaluate each ‘best' compromise rain gauge network. The performance statistics for model runs from all ‘best' networks were evaluated against a calibrated simulation of KINEROS2 based on the full spatial extent of the KED rainfall map (representing an installation of 94 rain gauges). In addition, to test how each ‘best' gauge network compared with random rain gauge configurations, average performance statistics for an ensemble of 1,000 randomly selected subsets of 1 to 4 grid cells were determined.

Troch, P. A.; Volkmann, T.; Lyon, S. W.; Gupta, H.

2009-04-01

359

Mitigating Drought through Weather Modification: Selected Institutional and Meteorological Issues in Texas. Volume 2: Radar Echo Characteristics in the Edwards Plateau - Balcones Escarpment Area of Texas.  

National Technical Information Service (NTIS)

This study reports the characteristics of rain cells (radar echoes) in the southern Edwards Plateau and Balcones Escarpment area of Texas as deduced from PPI photographs, as film, of the WSR-57 (10 cm) radar at Hondo, Texas. The periods analyzed are divid...

D. M. Driscoll

1982-01-01

360

Greatest Point and Areal Rainfalls  

Microsoft Academic Search

\\u000a Weather systems of the tropics and extra tropics generate heavy to very heavy rainfall for periods of days in various parts\\u000a of the world, as discussed in Chapter 5. The heavy rainfall events may last 3 to 4 days and are responsible for causing floods,\\u000a landslides, levee breaches, dams overtopping, sedimentation, erosion and other such occurrences. Flooding from some of

Pukh Raj Rakhecha; Vijay P. Singh

361

Tomography applied to radiobase network for real time estimation of the rainfall rate fields  

NASA Astrophysics Data System (ADS)

Recently we proposed a novel remote sensing method for rainfall rate estimation in real time by means of tomographic processing applied to power attenuation measurements made across the microwave links defined by radiobase station networks for mobile communication systems. In this paper we present a new tomographic algorithm that has been specifically developed for the typical topology of the urban radiobase station networks. Such algorithm has been tested on simulated specific attenuation (K) maps based on true polarimetric weather radar data. We assumed 18, 23, and 38 GHz for the carrier frequencies of the radiobase network and the weather data gathered by the POLAR55 C polarimetric radar located in Rome, Italy. Simulation results of rainfall rate estimation applying the new tomographic algorithm to the current radiobase station configuration over the main Italian cities are presented. We simulated the attenuation measurements along the microwave radiolinks by using true polarimetric weather radar measurements (mainly absolute reflectivity ZH and ZV) to which the well known Z-K relationships have been applied. The specific attenuation maps are then used to simulate the power attenuation measurements along the true microwave radiolink network. We made several simulations using different rainfall events and different radiolink network topologies to test the reconstruction performance of the presented tomographic algorithm. We found out that the number of possible microwave radiolinks of the current urban network is much higher than the number of links that is generally sufficient to provide a quite good estimate of the specific attenuation map. This implies that the radiolink number, that generally is available in a radiobase network of a mobile communication system for a medium-size urban area like that of the main Italian cities, is certainly sufficient for a rainfall estimation system based on the proposed tomographic processing. The importance of this approach for rainfall monitoring is self-evident, since it would allow to provide high-density rainfall estimates exploiting an existing infrastructure for measurements with a very limited additional cost. In fact high density radiobase station networks for mobile communication systems (i.e. GSM, GPRS, UMTS) are nowadays available, especially in populated urban areas and along the major roads and communication routes. Such radio networks encompass a high number of microwave radio links of different lengths (from hundreds of meters to dozens of kilometers), depending on the relative disposition of the radiobase stations. The proposed approach could be used to monitor the rainfall rate over critical areas - like dense urban areas or strict valleys crossed by busy motorways - that are generally characterized by the presence of dense radiobase networks but often not (completely) visible by other remote sensing systems such as weather radars that, though more expensive, are limited by orography: in fact, the choice of a radar site in orographically complex areas is often the result of a difficult compromise among different requirements, while the distributed approach of the tomographic network has not this kind of drawback.

Cuccoli, Fabrizio; Facheris, Luca; Baldini, Luca; Gorgucci, Eugenio; Gori, Stefano

2010-05-01

362

Summer Weather on Haleakala, Maui.  

National Technical Information Service (NTIS)

Meteorological observations from the summit of Haleakala, Maui, high-resolution satellite imagery, and rainfall climatology are examined to determine diurnal and day-to-day variations in weather both at the summit and along the slopes. Results show larges...

S. W. Lyons

1979-01-01

363

Comparison of TRMM precipitation radar with NEXRAD and in-situ rain gauges in central and south Florida  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to use various mathematical methods for processing precipitation data and presenting an independent ground-based measurement of rainfall rate and accumulation for calibration of TRMM Precipitation Radar (PR). Reflectivity data from the Melbourne National Weather Service WSR-88D Next generation Radar (NEXRAD) were collocated in time and space with gauge data located in Central and South Florida. The corresponding NEXRAD reflectivity (Z) and gauge rain states (R) were matched. Different regression methods were tested to find a suitable Z-R relationship for convective and stratiform rainfall for Melbourne NEXRAD. This Z-R relationship was used to produce instantaneous rain rate maps, and monthly rain accumulation maps. This resulted in a large coverage area for comparison with TRMM PR rain products; instantaneous rain rate, and average monthly rain rate. Statistics are presented for three months operations during August and September 1998, and June 1999.

Han, Qinghua; Eubanks, Chris; Jones, W. Linwood; Kasparis, Takis

2000-07-01

364

Spatial averaging of oceanic rainfall variability using underwater sound: Ionian Sea rainfall experiment 2004.  

PubMed

An experiment to evaluate the inherent spatial averaging of the underwater acoustic signal from rainfall was conducted in the winter of 2004 in the Ionian Sea southwest of Greece. A mooring with four passive aquatic listeners (PALs) at 60, 200, 1000, and 2000 m was deployed at 36.85 degrees N, 21.52 degrees E, 17 km west of a dual-polarization X-band coastal radar at Methoni, Greece. The acoustic signal is classified into wind, rain, shipping, and whale categories. It is similar at all depths and rainfall is detected at all depths. A signal that is consistent with the clicking of deep-diving beaked whales is present 2% of the time, although there was no visual confirmation of whale presence. Co-detection of rainfall with the radar verifies that the acoustic detection of rainfall is excellent. Once detection is made, the correlation between acoustic and radar rainfall rates is high. Spatial averaging of the radar rainfall rates in concentric circles over the mooring verifies the larger inherent spatial averaging of the rainfall signal with recording depth. For the PAL at 2000 m, the maximum correlation was at 3-4 km, suggesting a listening area for the acoustic rainfall measurement of roughly 30-50 km(2). PMID:18397003

Nystuen, Jeffrey A; Amitai, Eyal; Anagnostou, Emmanuel N; Anagnostou, Marios N

2008-04-01

365

EarthWatch: Weather on Demand  

NSDL National Science Digital Library

This site provides weather headlines, a StormWatch center, a national forecast center, satellite and radar information, maps of current weather conditions (including temperature, wind chill, radar, and satellite images across the United States), and a hurricane and tropical storm satellite image archive. The satellite image coverage also includes Canada, Mexico, the Caribbean, Gulf of Mexico, and Pacific and Atlantic oceans.

366

Weather Depot 1.21  

NSDL National Science Digital Library

As a quote commonly misattributed to Mark Twain goes, "Everyone talks about the weather, but no one does a thing about it." This little program from the folks at Weather Depot won't allow users to modify weather conditions, but it will let users customize their own weather planner (with hourly and daily updates), view regional radar, and view a map of current temperatures around the United States. Additionally, users may look up current road conditions, and view weather Web cams. Weather Depot 1.21 is compatible with all systems running Windows 98 and higher.

367

Retrieving rainfall fields through tomographic processing applied to radio base network signals  

NASA Astrophysics Data System (ADS)

As shown in the past years by researchers at the University of Florence, rainfall rate can be estimated in real time by means of tomographic processing applied to power attenuation measurements made simultaneously along microwave links. In this paper, we focus on the possibility to exploit the 'opportunity signals' provided by radio-base station networks for mobile communication systems. We describe a new tomographic algorithm that has been specifically developed for such kind of networks in urban areas, where a high number of microwave connections is typically possible. We describe the performance of the algorithm after having tested it on a 2 hours simulated rainfall event based on a sequence of real weather radar observations and on three kind of link networks, symmetric with lower link density and asymmetric with lower and higher density. We considered 12 GHz for the test carrier frequency of the radio-base network.

Cuccoli, Fabrizio; Facheris, Luca; Gori, Stefano; Baldini, Luca

2011-10-01

368

Mechanisms for Diurnal Variability of Global Tropical Rainfall Observed from TRMM.  

National Technical Information Service (NTIS)

The behavior and various controls of diurnal variability in tropical-subtropical rainfall are investigated using Tropical Rainfall Measuring Mission (TRMM) precipitation measurements retrieved from: (1) TRMM Microwave Imager (TMI), (2) Precipitation Radar...

S. Yang E. A. Smith

2004-01-01

369

Space-time simulation of intermittent rainfall with prescribed advection field: Adaptation of the turning band method  

NASA Astrophysics Data System (ADS)

Space-time rainfall simulation is useful to study questions like, for instance, the propagation of rainfall-measurement uncertainty in hydrological modeling. This study adapts a classical Gaussian field simulation technique, the turning-band method, in order to produce sequences of rainfall fields satisfying three key features of actual precipitation systems: (i) the skewed point distribution and the space-time structure of nonzero rainfall (NZR); (ii) the average probability and the space-time structure of intermittency; and (iii) a prescribed advection field. The acronym of our simulator is SAMPO, for simulation of advected mesoscale precipitations and their occurrence. SAMPO assembles various theoretical developments available from the literature. The concept of backtrajectories introduces a priori any type of advection field in the heart of the turning band method (TBM). TBM outputs transformation into rainfall fields with a desired structure is controlled using Chebyshev-Hermite polynomial expansion. The intermittency taken as a binary process statistically independent of the NZR process allows the use of a common algorithm for both processes. The 3-D simulation with a space-time anisotropy captures important details of the precipitation kinematics summarized by the Taylor velocity of both NZR and intermittency. A case study based on high-resolution weather radar data serves as an example of model inference. Illustrative simulations revisit some classical questions about rainfall variography like the influence of advection or intermittency. They also show the combined role of Taylor's and advection velocities.

Leblois, Etienne; Creutin, Jean-Dominique

2013-06-01

370

Comparison of two satellite-based rainfall algorithms using pacific atoll raingage data  

Microsoft Academic Search

Rainfall estimates for two simple satellite-based rainfall algorithms are verified over the tropical Pacific using a new method that incorporates sparsely distributed raingages. The resulting linear regression relationship between monthly areal rainfall and the highly reflective cloud index agrees with earlier results. However, the GOES precipitation index (GPI), which was calibrated using radar rainfall data obtained from the eastern tropical

Mark L. Morrissey; J. Scott Greene

1993-01-01

371

Quality Control and Calibration of the Dual-Polarization Radar at Kwajalein, RMI.  

National Technical Information Service (NTIS)

Weather radars, recording information about precipitation around the globe, will soon be significantly upgraded. Most of today s weather radars transmit and receive microwave energy with horizontal orientation only, but upgraded systems have the capabilit...

A. Tokay D. A. Marks D. B. Wolff L. D. Carey

2010-01-01

372

The potential of radar-based ensemble forecasts for flash-flood early warning in the southern Swiss Alps  

NASA Astrophysics Data System (ADS)

This study explores the limits of radar-based forecasting for hydrological runoff prediction. Two novel radar-based ensemble forecasting chains for flash-flood early warning are investigated in three catchments in the southern Swiss Alps and set in relation to deterministic discharge forecasts for the same catchments. The first radar-based ensemble forecasting chain is driven by NORA (Nowcasting of Orographic Rainfall by means of Analogues), an analogue-based heuristic nowcasting system to predict orographic rainfall for the following eight hours. The second ensemble forecasting system evaluated is REAL-C2, where the numerical weather prediction COSMO-2 is initialised with 25 different initial conditions derived from a four-day nowcast with the radar ensemble REAL. Additionally, three deterministic forecasting chains were analysed. The performance of these five flash-flood forecasting systems was analysed for 1389 h between June 2007 and December 2010 for which NORA forecasts were issued, due to the presence of orographic forcing. A clear preference was found for the ensemble approach. Discharge forecasts perform better when forced by NORA and REAL-C2 rather then by deterministic weather radar data. Moreover, it was observed that using an ensemble of initial conditions at the forecast initialisation, as in REAL-C2, significantly improved the forecast skill. These forecasts also perform better then forecasts forced by ensemble rainfall forecasts (NORA) initialised form a single initial condition of the hydrological model. Thus the best results were obtained with the REAL-C2 forecasting chain. However, for regions where REAL cannot be produced, NORA might be an option for forecasting events triggered by orographic precipitation.

Liechti, K.; Panziera, L.; Germann, U.; Zappa, M.

2013-10-01

373

PATH TO NEXRAD: Doppler Radar Development at the National Severe Storms Laboratory  

Microsoft Academic Search

In this historical paper, we trace the scientific- and engineering-based steps at the National Severe Storms Laboratory (NSSL) and in the larger weather radar community that led to the development of NSSL's first 10-cm-wavelength pulsed Doppler radar. This radar was the prototype for the current Next Generation Weather Radar (NEXRAD), or Weather Surveillance Radar-1998 Doppler (WSR-88D) network.We track events, both

Rodger A. Brown; John M. Lewis

2005-01-01

374

3D Structure of the Heavy Precipitation in South China by Dual-Doppler Radar  

NASA Astrophysics Data System (ADS)

As a result of the effect of the trough at 500hPa, the shear line at 850hPa and the low level cold air, it produced a heavy precipitation in the north region of Guangdong province and Pearl River Delta in China, up to 199.5mm rainfall from 01LST to 04LST and 99.1mm rainfall on 02LST 7 May 2010 at Wushan, 107.4mm rainfall on 02LST 7 May at Dongguan station. The one hour precipitation at Wushan has broken the record. The three dimensional wind fields were retrieved by the volume scan data of the dual-Doppler radar located in Guangzhou and Shenzhen cities. The structure evolution of the 3D wind fields of the heavy rainfall was investigated. It is a convective cloud precipitation as the radar echo analyses shown. The reflectivity is very strong at the heavy precipitation period time that the maximum value is more than 55dBZ. The supercell, bow-echo and the squall line located on the M?CS played an important role on this heavy rainfall. The dual-Doppler retrieval wind show that the heavy rainfall was induced by the meso-?-scale convergence line and the meso-?-scale vortex at the low and medium levels. The meso-?-scale convergence line triggered and maintained the heavy rainfall. The meso-?-scale convergence line moved southeastward. It stayed at Guangzhou and Dongguan city for period of time. There were strong convergence and vorticity at the low and medium levels of the M?CS. The rainband moved southeastward while the convergence line propagated along the same direction. Acknowledgements The work was supported by the Grant Agency of the National Science Foundation of China (grant 40975015, 40605014), the Grant Agency of the National Key Basic Research and Development Project of China (grant 2004CB418305), and the foundation of state key laboratory of severe weather.

Haiguang, Z.

2010-09-01

375

Radar meteorology: highlights of recent advances  

Microsoft Academic Search

Radar meteorology has recently reached new heights of operational and scientific development. This has been fostered largely by the installation of the first generation of operational NEXRAD (WSR-88D) Doppler radars across the USA, the initiation of a demonstration network of operational radar wind profilers in the central USA, and the early installation of the first of the Terminal Doppler Weather

David Atlas

1994-01-01

376

Radar Technology Applied to Air Traffic Control  

Microsoft Academic Search

Use of primary radars for air traffic control (ATC) is discussed. The location and the parameters of various ATC radars are described. The clutter environment (land clutter, birds, automobiles, and weather) has had a major impact on the configuration of these radars. Signal-processing techniques and antenna techniques utilized to cope with the clutter are described. Future signal-processing techniques for the

WILLIAM W. SHRADER

1973-01-01

377

Frequency and intensity of precipitation events as seen by the TRMM Precipitation Radar  

NASA Astrophysics Data System (ADS)

We present a very high-resolution (0.05° x 0.05° , about 5km x 5km) monthly climatology and 3-hourly diurnal cycle of precipitation frequency and intensity, as derived from the precipitation radar (PR) aboard TRMM. We show how variations in the frequency of precipitation events dominate over variations in the mean intensity of precipitation to determine local rain rates. In subtropical regions such as the Mediterranean and over the Gulf Stream, climatological rainfall frequency changes very sharply at coastlines and over SST maxima, indicating a strong control of convection by the surface properties, even when rainfall is embedded in large scale weather systems. In some regions of the tropics, diurnally locked local circulations are largely responsible for sharp gradients in the spatial distribution of precipitation frequency and seasonal mean precipitation. Spatial variations in intensity have a large-scale character and sharp gradients appear only in the ice layer, but not at the surface. They indicate a preference for the most intense rainfall to occur in locations and at times when rainfall is relatively infrequent (but not rare). We suggest that regions of frequent rainfall and regions of intense rainfall might influence the stability of the tropical troposphere in different fashions.

Biasutti, M.; Sobel, A. H.; Yuter, S. E.; Burleyson, C. D.

2011-12-01

378

The potential of cellular network infrastructures for sudden rainfall monitoring in dry climate regions  

NASA Astrophysics Data System (ADS)

Monitoring of precipitation and in particular sudden rain, in rural dry climate regions, is a subject of great significance in several weather related processes such as soil erosion, flash flooding, triggering epidemics and more. The rainfall monitoring facilities in these regions and as a result precipitation data are, however, commonly, severely lacking. As was recently shown, cellular networks infrastructures supply high resolution precipitation measurements at ground level while often being situated in dry areas, covering large parts of these climatic zones. The potential found in these systems to provide early monitoring and essential precipitation information, directly from arid regions, based on standard measurements of commercial microwave links, is exemplified here over the Negev and the Southern Judean desert, South Israel. We present the results of two different rainfall events occurred in these regions. It is shown that the microwave system measured precipitation between at least 50 min (in case 1) and at least 1 h and 40 min (in case 2) before each of the sparse rain gauges. During each case, the radar system, located relatively far from the arid sites, provided measurements from heights of at least 1500 m and 2000 m above surface, respectively. A third case study demonstrates a relative advantage of microwave links to measure precipitation intensity with respect to the radar system, over an area of complex topography located in northeastern Israel, which is relatively far (~ 150 km) from the radar.

David, N.; Alpert, P.; Messer, H.

2013-09-01

379

A Copula Based Space-Time Rainfall Simulation Model  

NASA Astrophysics Data System (ADS)

Stochastically generated rainfall data are used as input to hydrological and meteorological models to assess model uncertainties and climate variability in water resources systems. Currently, there are very well defined methods to generate time series of rainfall data for a single point. However, hydrological and meteorological modeling over large scales requires high resolution rainfall data to capture temporal and spatial variability of rainfall that is proven to affect the quality of hydrological predictions (Osborn and Reynolds, 1963; Osborn and Keppel, 1966; Rodda, 1967; Dawdy and Bergman, 1969, Seliga et al., 1992; Corradini and Singh, 1985; Obled et al., 1994; Troutman, 1983; Hamlin, 1983; Faures et al., 1995; Shah et al., 1996, Goodrich et al., 1995). In this paper a copula base space-time rainfall simulation model is introduced for simulation of two-dimensional rainfall field based on observed radar data. In contrast with most rainfall simulation techniques, which describe the spatial dependence structure of rainfall fields with a covariance function or a variogram, we introduce spatial dependence without the influence of the marginal distribution using copula. Radar data of the state of Baden-Württemberg in Germany with temporal resolution of 5min and spatial resolution of 1 km2 are used in this study. Gaussian copula and a number of non-Gaussian copulas are used to describe the dependency structure of radar rainfall data. For each radar image, realizations of radar rainfall patters are simulated. The simulation technique used in this work preserves the spatial dependence structure as well and temporal variability of simulated fields similar to the observed radar data. Each simulated realization is then used as input to a hydrological model resulting in an ensemble of predicted runoff hydrographs. The main conclusions are: (a) copula techniques can be used to describe the spatial dependence structure or rainfall fields instead of a simple covariance function; (b) rainfall is not Gaussian and using Gaussian based simulation techniques lead to unrealistic simulated fields.

Aghakouchak, A.; Bárdossy, A.; Habib, E.

2008-05-01

380

Representing radar QPE and QPF uncertainties using radar ensembles  

NASA Astrophysics Data System (ADS)

In the last years, new comprehension of the physics underlying the radar measurements as well as new technological advancements have allowed radar community to propose better algorithms and methodologies and significant advancements have been achieved in improving Quantitative Precipitation Estimates (QPE) and Quantitative Precipitation forecasting (QPF) by radar. Thus the study of the 2D uncertainties field associated to these estimates has become an important subject, specially to enhance the use of radar QPE and QPF in hydrological studies, as well as in providing a reference for satellite precipitations measurements. In this context the use of radar-based rainfall ensembles (i.e. equiprobable rainfall field scenarios generated to be compatible with the observations/forecasts and with the inferred structure of the uncertainties) has been seen as an extremely interesting tool to represent their associated uncertainties. The generation of such radar ensembles requires first the full characterization of the 3D field of associated uncertainties (2D spatial plus temporal), since rainfall estimates show an error structure highly correlated in space and time. A full methodology to deal with this kind of radar-based rainfall ensembles is presented. Given a rainfall event, the 2D uncertainty fields associated to the radar estimates are defined for every time step using a benchmark, or reference field, based on the best available estimate of the rainfall field. This benchmark is built using an advanced non parametric interpolation of a dense raingauge network able to use the spatial structure provided by the radar observations, and is confined to the region in which this combination could be taken as a reference measurement (Velasco-Forero et al. 2008, doi:10.1016/j.advwatres.2008.10.004). Then the spatial and temporal structures of these uncertainty fields are characterized and a methodology to generate consistent multiple realisations of them is used to generate the radar-based rainfall ensembles scenarios. This methodology, based on the improvement of the "String of Beads" model (Pegram and Clothier, 2001, doi:10.1016/S0022-1694(00)00373-5), is designed to preserve their main characteristics, such as anisotropy and the temporal variations of their spatial correlation. The discussion of the results on an illustrative case study and their potential interest in hydrological applications is also discussed.

Sempere-Torres, D.; Llort, X.; Roca, J.; Pegram, G.

2009-09-01

381

Stochastic weather type simulation for regional climate change impact assessment  

Microsoft Academic Search

A stochastic model is developed for the synthesis of daily precipitation by weather type analysis. Daily rainfall at two sites in southern England is related to the Lam weather types by using conditional probabilities. Time series of circulation patterns and hence rainfall are then generated using a Markov representation of matrices of transition probabilities between weather types. The model reproduces

Robert L. Wilby

1994-01-01

382

Stochastic weather type simulation for regional climate change impact assessment  

Microsoft Academic Search

A stochastic model is developed for the synthesis of daily precipitation by weather type analysis. Daily rainfall at two sites in southern England is related to the Lamb weather types by using conditional probabilities. Time series of circulation patterns and hence rainfall are then generated using a Markov representation of matrices of transition probabilities between weather types. The model reproduces

Robert L. Wilby

1994-01-01

383

Millimeter radar  

Microsoft Academic Search

The paper discusses some of the advantages offered by millimeter waves over microwaves, reviews possible and past millimeter radar applications, and looks at some future millimeter radar systems. The coming millimeter radars include radiometric seekers, radiometers, and high resolution radar for satellite identification. Important problems to be resolved before millimeter radars can be put into production include component capability; radar

S. L. Johnston

1977-01-01

384

Dan's Wild Wild Weather Page  

NSDL National Science Digital Library

This website contains information, maps, photos, and links to everything about the weather. Topics covered include radar, climate, tornadoes, clouds, precipitation, lightning, humidity, temperature, forecasting, hurricanes, wind, and pressure. Each of these topics contains a brief description with links to weather maps, websites, and learning activities. There is a teachers section with links to specific lesson plan and unit resources.

Satterfield, Dan

385

A Quality Control Concept for Radar Reflectivity, Polarimetric Parameters, and Doppler Velocity  

Microsoft Academic Search

Over the last few years the use of weather radar data has become a fundamental part of various applications like rain-rate estimation, nowcasting of severe weather events, and assimilation into numerical weather prediction models. The increasing demand for radar data necessitates an automated, flexible, and modular quality control. In this paper a quality control procedure is developed for radar reflectivity

Katja Friedrich; Martin Hagen; Thomas Einfalt

2006-01-01

386

Multiparameter radar analysis using wavelets  

NASA Astrophysics Data System (ADS)

Multiparameter radars have been used in the interpretation of many meteorological phenomena. Rainfall estimates can be obtained from multiparameter radar measurements. Studying and analyzing spatial variability of different rainfall algorithms, namely R(ZH), the algorithm based on reflectivity, R(ZH, ZDR), the algorithm based on reflectivity and differential reflectivity, R(KDP), the algorithm based on specific differential phase, and R(KDP, Z DR), the algorithm based on specific differential phase and differential reflectivity, are important for radar applications. The data used in this research were collected using CSU-CHILL, CP-2, and S-POL radars. In this research multiple objectives are addressed using wavelet analysis namely, (1)space time variability of various rainfall algorithms, (2)separation of convective and stratiform storms based on reflectivity measurements, (3)and detection of features such as bright bands. The bright band is a multiscale edge detection problem. In this research, the technique of multiscale edge detection is applied on the radar data collected using CP-2 radar on August 23, 1991 to detect the melting layer. In the analysis of space/time variability of rainfall algorithms, wavelet variance introduces an idea about the statistics of the radar field. In addition, multiresolution analysis of different rainfall estimates based on four algorithms, namely R(ZH), R( ZH, ZDR), R(K DP), and R(KDP, Z DR), are analyzed. The flood data of July 29, 1997 collected by CSU-CHILL radar were used for this analysis. Another set of S-POL radar data collected on May 2, 1997 at Wichita, Kansas were used as well. At each level of approximation, the detail and the approximation components are analyzed. Based on this analysis, the rainfall algorithms can be judged. From this analysis, an important result was obtained. The Z-R algorithms that are widely used do not show the full spatial variability of rainfall. In addition another intuitively obvious result was observed namely, R( KDP) has reduced the spatial variability due to smoothing of KDP estimates. The convective and stratiform separation was studied using multiresolution analysis. The June 22, 1995 data collected by CSU-CHILL radar were used to evaluate the technique. Another set of data collected on August 23, 1991 representing stratiform conditions were also studied.

Tawfik, Ben Bella Sayed

387

JAWS (Joint Airport Weather Studies) Multiple Doppler Derived Winds.  

National Technical Information Service (NTIS)

An elementary working knowledge is given of the advantages and limitations of the multiple Doppler radar analyses that have recently become available from the Joint Airport Weather Studies (JAWS) project. What Doppler radar is and what it does is addresse...

K. L. Elmore

1987-01-01

388

Evaluation of the QPF of convective flash flood rainfalls over the Czech territory in 2009  

NASA Astrophysics Data System (ADS)

In this paper, quantitative precipitation forecasts (QPF) are evaluated using several verification techniques and analysis of the results from these techniques. The forecasts were produced by two limited-area numerical weather prediction models: the ALADIN-CZ model operated by the Czech Hydro-Meteorological Institute (CHMI) and the COSMO model operated by the German Weather Service (DWD). Each model was run using two horizontal resolutions over the domain covering the Czech Republic. The ALADIN-CZ model outputs were obtained using resolutions of approximately 9 km and 4.7 km, and the COSMO model outputs were obtained using resolutions of approximately 7 km and 2.8 km.The forecast quality is studied for the flash flood period that occurred in June and July of 2009, when convective rainfalls with durations of 1 to 3 h and a return period of more than 100 years caused devastating floods in many Czech localities. The radar-based rainfalls used to verify the forecasts were produced by the CHMI operational product MERGE, which merges radar-derived rainfalls with the rainfalls that are measured by ground rain gauges.A series of 56 consecutive forecasts of 3-h rainfalls were verified using traditional and spatial verification techniques, and the results from these analyses were compared. The verification was performed using traditional verification scores based on a contingency table, spatial verification by the fractions skill score (FSS) and the SAL (structure–amplitude–location) technique. The FSS represents a fuzzy verification technique and compares the fractional coverage of precipitation grids over a threshold in spatial windows around the observations and forecasts. The SAL is a spatial object-oriented verification technique used to evaluate the structure, amplitude, and location of a precipitation field.The quality of QPF depends strongly on the scale of convective precipitation, and all models provide good forecast quality for extended rainfall systems. The opposite is true for the local and more or less chaotic convection during the final part of the time period. The FSS indicates how the results depend on the threshold and scale of precipitation. The COSMO 2.8 model is able to determine the largest local rainfall values, but models with lower resolution, such as the ALADIN 9 km and COSMO 7 km, provide better results for lower thresholds and larger scales. The use of more verification techniques is suitable for a modeller-oriented evaluation of different aspects of forecast quality.

Zacharov, Petr; Rezacova, Daniela; Brozkova, Radmila

2013-09-01

389

Stochastic disaggregation of monthly rainfall data for crop simulation studies  

Microsoft Academic Search

Stochastic weather generators are useful for producing daily sequences that reproduce climatic statistics aggregated to, e.g., a monthly time scale, for use with biological simulation models. This paper describes a stochastic weather generator that disaggregates monthly rainfall by adjusting input parameters or by constraining output to match target rainfall totals, and demonstrates its use with a maize crop simulation model

James W. Hansen; Amor V. M. Ines

2005-01-01

390

Radar Images of the Earth: Volcanoes  

NSDL National Science Digital Library

This site features links to thirty-five NASA radar images of the world's volcanoes, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

391

Radar Images of the Earth: Oceans  

NSDL National Science Digital Library

This site features links to seven NASA radar images of the world's oceans, including brief descriptions of the respective processes and settings. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

392

Radar Images of the Earth: Cities  

NSDL National Science Digital Library

This site features links to more than fifty NASA radar images of the world's cities, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

393

Space Radar Images of the Earth: Archaeology  

NSDL National Science Digital Library

This site features links to twelve NASA radar images of the world's famous archaeology sites, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

394

Radar Images of the Earth: Interferometry  

NSDL National Science Digital Library

This site features links to nineteen NASA radar images using interferometry to enhance details or measure changes in elevation. The image pages contain brief descriptions of the respective processes and settings. They were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

395

APPLICATION OF WEATHER RADAR TO FALLOUT PREDICTION. Quarterly Technical Report No. 4 covering Period December 1, 1958 through February 28, 1959  

Microsoft Academic Search

In instrumentation work, plans have been made to attach equipment to the ; AN\\/CPS-9 radar which will present the data in the form of range-corrected signal ; intensity contours. Work will begin immediately on the construction of this ; equipment and the modification required for its installation. Instrumentation ; and calibration of pairs of Pulse Integrators and R-meters and the

1959-01-01

396

Bistatic synthetic aperture radar  

Microsoft Academic Search

Synthetic aperture radar (SAR) is becoming increasingly important in many military ground surveillance and targeting roles because of its ability to operate in all weather, day and night, and to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and receiver are on separate platforms, is seen as a potential means of countering vulnerability. This

A. M. Horne; G. Yates

2002-01-01

397

The Impacts of the Urban Environment on Extreme Rainfall from Warm Season Thunderstorm Systems  

NASA Astrophysics Data System (ADS)

The spatial variability of extreme rainfall over urban environments and its change in time is examined from both a climatological and a case-study perspective. The areas of focus are the Washington D.C-Baltimore and New York City Metropolitan areas. Climatological analyses utilize Cloud-to-Ground lightning data from the National Lightning Detection Network (NLDN) and radar-rainfall products from the HydroNEXRAD project. The regional distribution of heavy convection, time-trends, initiation locations and extreme thunderstorm lifecycle characteristics are presented for both areas. Case studies include a collection of extreme events over the two Metropolitan areas that combine detailed observations and mesoscale modeling using the Weather Research and Forecasting (WRF) model with chemistry and cloud-aerosol interaction (WRF-Chem) capabilities. The impacts of the urban environment on extreme thunderstorm evolution, in terms of the Urban Heat Island (UHI), the Urban Canopy Layer (UCL), and urban aerosols are examined for this collection of events. High-resolution urban data is incorporated in the modeling scheme with the use of the Urban Canopy Model capability of WRF. Key results of the study include large differences in rainfall accumulation when aerosols and chemistry are included in the model that hint to the role of hygroscopic aerosols on extreme warm season thunderstorm evolution. The urban environment itself impacts the rainfall distribution and movement of extreme thunderstorms, in the urban vicinity, mainly through the impacts of the urban canopy layer and aerosols.

Ntelekos, A. A.; Smith, J. A.; Krajewski, W. F.; Baeck, M.; Zhang, Y.

2007-12-01

398

Sensitivity Analysis of Satellite Rainfall Forcing and Land-surface Model Parameter Uncertainty on Soil Moisture Prediction  

NASA Astrophysics Data System (ADS)

A sensitivity analysis was carried out to investigate the uncertainty in the simulation of soil moisture by integrating a land surface model, forced with hydro-meteorological data. The study seeks to address the characterization of two sources of uncertainty: 1) errors in the rainfall estimation from sensor observations; and, 2) the land surface model parametric error, which manifests as non-uniqueness in soil hydraulic parameters. The study is conducted in the Oklahoma region, which presents a good coverage by weather radars, multi-year satellite rainfall products and in-situ meteorological and soil moisture measurement stations. The land surface model that has been chosen is the NASA Catchment Land Surface Model (CLSM; Koster et al., 2000). The framework to characterize the parametric error is represented by the generalized likelihood uncertainty estimation (GLUE) technique. The forcing rainfall uncertainty is analyzed through an error model included in the NASA Land Data Assimilation System (LDAS), which is applied to satellite rainfall fields to obtain an ensemble of equiprobable realizations of precipitation. The perturbed precipitation fields are propagated through CLSM to produce multiple ensembles of soil moisture. This numerical experiment allows us to quantify the propagation of uncertainty from rainfall to soil moisture prediction, accounting for the two main error sources, i.e. rainfall forcing and land surface model parameterizations. In previous studies we have shown how satellite-rainfall error alone can impact soil moisture uncertainty. Results from this study will complement these initial findings to quantify the relative impact of rainfall vs modeling error and the combined uncertainty on the prediction of soil moisture.

Maggioni, V.; Anagnostou, E. N.; Reichle, R. H.

2010-12-01

399

Diurnal Land Sea Rainfall Peak Migration over Sumatera Island, Indonesian Maritime Continent, Observed by TRMM Satellite and Intensive Rawinsonde Soundings  

Microsoft Academic Search

The diurnal cycle of rainfall and its regional variation over Sumatera Island, Indonesian Maritime Continent, are examined using Tropical Rainfall Measuring Mission (TRMM) satellite precipitation radar (PR) and intensive rawinsonde sounding data. The TRMM PR sensor can detect raindrops directly, regardless of ground and cloud conditions, and can distinguish between convective and stratiform types of rainfall. Rainfall variation over this

Shuichi Mori; Hamada Jun-Ichi; Yudi Iman Tauhid; Manabu D. Yamanaka; Noriko Okamoto; Fumie Murata; Namiko Sakurai; Hiroyuki Hashiguchi; Tien Sribimawati

2004-01-01

400

A new regional RADAR network for nowcasting applications: the RESMAR achievements  

NASA Astrophysics Data System (ADS)

Monitoring weather phenomena from radar has an essential role in nowcasting applications. As one of the most useful sources of quantitative precipitation estimation, rainfall radar analysis can be a very useful research tool in supporting methods for rainfall forecasting. Its short-term prediction is often needed in various meteorological and hydrological applications where accurate prediction of rainfall is essential from national service and civil protection forecasting up to agriculture and urban issues. Very recently, Tuscany region (central Italy) is equipped with two X-band radars with a maximum range of 108 km, a beam width of 3° and a high spatial resolution (i.e., radial resolution up to 90m), located in Livorno and Cima del Monte (Elba island) sites. The first system is property of Livorno's port Authority, the second one of Consorzio LaMMA (Laboratory of Monitoring and Environmental Modelling for the sustainable development) who has installed it in the framework of "RESMAR - Environmental Resources in the MARitime Space" activities, a strategic project, financed in the framework of the European Cross-Border Cooperation Programme Italy-France "Maritime", coordinated by the Liguria Region Administration. Both systems are managed by LaMMA. The cross-border sharing of such relevant meteorological observation instruments and the integration of these data with existing tools and methodologies is intended to improve operational regional weather services in nowcasting activities and their impacts on the territory, as those related to LaMMA daily issues. This sharing is widely promoted within RESMAR project between the different partner regions (ARPA-Sardinia, Meteo-France and Liguria). The integration of these data with other complementary and ancillary measurements is also needed to increase the reliability and accuracy of radar measurements in view of both a better meteorological phenomena understanding and quantitative precipitation estimation. The use of satellite data largely improves the spatial and temporal information on the events, filling up the gaps of uneven data distribution; for this issue LaMMA has multi-year skills in the acquisition and processing of geostationary and polar satellites. The regional raingauge network and meteorological stations will be instead used to obtain useful information both to calibration (as those related to radar reflectivity - rain rate relationships) and validation processes. The radar system and its mosaicking will be presented, as well as some preliminary products.

Antonini, Andrea; Melani, Samantha; Mazza, Alessandro; Ortolani, Alberto; Gozzini, Bernardo; Corongiu, Manuela; Cristofori, Simone

2013-04-01