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Sample records for weather radar rainfall

  1. Weather radar rainfall data in urban hydrology

    NASA Astrophysics Data System (ADS)

    Thorndahl, Søren; Einfalt, Thomas; Willems, Patrick; Ellerbæk Nielsen, Jesper; ten Veldhuis, Marie-Claire; Arnbjerg-Nielsen, Karsten; Rasmussen, Michael R.; Molnar, Peter

    2017-03-01

    Application of weather radar data in urban hydrological applications has evolved significantly during the past decade as an alternative to traditional rainfall observations with rain gauges. Advances in radar hardware, data processing, numerical models, and emerging fields within urban hydrology necessitate an updated review of the state of the art in such radar rainfall data and applications. Three key areas with significant advances over the past decade have been identified: (1) temporal and spatial resolution of rainfall data required for different types of hydrological applications, (2) rainfall estimation, radar data adjustment and data quality, and (3) nowcasting of radar rainfall and real-time applications. Based on these three fields of research, the paper provides recommendations based on an updated overview of shortcomings, gains, and novel developments in relation to urban hydrological applications. The paper also reviews how the focus in urban hydrology research has shifted over the last decade to fields such as climate change impacts, resilience of urban areas to hydrological extremes, and online prediction/warning systems. It is discussed how radar rainfall data can add value to the aforementioned emerging fields in current and future applications, but also to the analysis of integrated water systems.

  2. SEVIRI rainfall retrieval and validation using weather radar observations

    NASA Astrophysics Data System (ADS)

    Roebeling, R. A.; Holleman, I.

    2009-11-01

    This paper presents and validates a new algorithm to detect precipitating clouds and estimate rain rates from cloud physical properties retrieved from the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The precipitation properties (PP) algorithm uses information on cloud condensed water path (CWP), particle effective radius, and cloud thermodynamic phase to detect precipitating clouds, while information on CWP and cloud top height is used to estimate rain rates. An independent data set of weather radar data is used to determine the optimum settings of the PP algorithm and calibrated it. For a 2-month period, the ability of SEVIRI to discriminate precipitating from nonprecipitating clouds is evaluated using weather radar over the Netherlands. In addition, weather radar and rain gauge observations are used to validate the SEVIRI retrievals of rain rate and accumulated rainfall across the entire study area and period. During the observation period, the spatial extents of precipitation over the study area from SEVIRI and weather radar are highly correlated (correlation ≈ 0.90), while weaker correlations (correlation ≈ 0.63) are found between the spatially mean rain rate retrievals from these instruments. The combined use of information on CWP, cloud thermodynamic phase, and particle size for the detection of precipitation results in an increase in explained variance (˜10%) and decrease in false alarms (˜15%), as compared to detection methods that are solely based on a threshold CWP. At a pixel level, the SEVIRI retrievals have an acceptable accuracy (bias) of about 0.1 mm h-1 and a precision (standard error) of about 0.8 mm h-1. It is argued that parts of the differences are caused by collocation errors and parallax shifts in the SEVIRI data and by irregularities in the weather radar data. In future studies we intend to exploit the observations of the European weather radar network Operational Programme for the Exchange of Weather Radar Information

  3. Decision making for urban drainage systems under uncertainty caused by weather radar rainfall measurement

    NASA Astrophysics Data System (ADS)

    Dai, Qiang; Zhuo, Lu; Han, Dawei

    2015-04-01

    With the rapidly growth of urbanization and population, the decision making for managing urban flood risk has been a significant issue for most large cities in China. A high-quality measurement of rainfall at small temporal but large spatial scales is of great importance to urban flood risk management. Weather radar rainfall, with its advantage of short-term predictability and high spatial and temporal resolutions, has been widely applied in the urban drainage system modeling. It is recognized that weather radar is subjected to many uncertainties and many studies have been carried out to quantify these uncertainties in order to improve the quality of the rainfall and the corresponding outlet flow. However, considering the final action in urban flood risk management is the decision making such as flood warning and whether to build or how to operate a hydraulics structure, some uncertainties of weather radar may have little or significant influence to the final results. For this reason, in this study, we aim to investigate which characteristics of the radar rainfall are the significant ones for decision making in urban flood risk management. A radar probabilistic quantitative rainfall estimated scheme is integrated with an urban flood model (Storm Water Management Model, SWMM) to make a decision on whether to warn or not according to the decision criterions. A number of scenarios with different storm types, synoptic regime and spatial and temporal correlation are designed to analyze the relationship between these affected factors and the final decision. Based on this, parameterized radar probabilistic rainfall estimation model is established which reflects the most important elements in the decision making for urban flood risk management.

  4. Improving weather radar estimates of rainfall using feed-forward neural networks.

    PubMed

    Teschl, Reinhard; Randeu, Walter L; Teschl, Franz

    2007-05-01

    In this paper an approach is described to improve weather radar estimates of rainfall based on a neural network technique. Other than rain gauges which measure the rain rate R directly on the ground, the weather radar measures the reflectivity Z aloft and the rain rate has to be determined over a Z-R relationship. Besides the fact that the rain rate has to be estimated from the reflectivity many other sources of possible errors are inherent to the radar system. In other words the radar measurements contain an amount of observation noise which makes it a demanding task to train the network properly. A feed-forward neural network with Z values as input vector was trained to predict the rain rate R on the ground. The results indicate that the model is able to generalize and the determined input-output relationship is also representative for other sites nearby with similar conditions.

  5. Detecting Rainfall Extreme Fields and Their Scaling Using Weather Radar Data

    NASA Astrophysics Data System (ADS)

    Hamidi, A.; Devineni, N.; Zahraei, A.; Khanbilvardi, R.

    2014-12-01

    Information on the probability of extreme rainfall events of various durations is required for hydraulic design in order to control storm runoff. Such information is usually expressed as a relationship between Intensity-Duration-Frequency (IDF) of extreme rainfall. The general IDF curve approach assumes a stationary climate and typically is regionalized based on small number of gauges. However, with the ongoing accumulation of weather radar records, radar-rainfall data represent an alternative to gauging data providing much needed spatial resolution. A clear understanding of the space-time rainfall patterns for events or for a season will enable in assessing the spatial distribution of areas likely to have a high/low inundation potential for each type of rainfall forcing. The Next Generation Weather Radar system (NEXRAD) comprises of 160 Weather Surveillance Radar-1988 Doppler (WSR-88D) sites throughout the United States and at selected overseas locations. Stage IV is a national multi-sensor radar product from NCEP, mosaicked from the regional multi-sensor analyses with 4km×4km and 1h resolution of space and time respectively. In the current study, 11 years of HRAP (Hydrologic Rainfall Analysis Project) gridded Stage IV radar data is employed to generate a relationship between intensity, duration, frequency and the storm exposed area of New York Metropolitan area covering almost 30,000 km2 of the most populous cities at the east part of United States. We investigate the statistical properties of the spatial manifestation of the rainfall exceedances and present the scaling phenomena of contiguous flooded areas as a result of large scale organization of storms. This can be used for spatially distributed flood risk assessment conditional on a particular rainfall scenario. Statistical models for spatio-temporal loss simulation including model uncertainty to support regional analysis can be developed. In this project, we explore a non-parametric multivariate approach

  6. Estimating the frequency of extreme rainfall using weather radar and stochastic storm transposition

    NASA Astrophysics Data System (ADS)

    Wright, Daniel B.; Smith, James A.; Villarini, Gabriele; Baeck, Mary Lynn

    2013-04-01

    Spatial and temporal variability in extreme rainfall, and its interactions with land cover and the drainage network, is an important driver of flood response. "Design storms," which are commonly used for flood risk assessment, however, are assumed to be uniform in space and either uniform or highly idealized in time. The impacts of these and other commonly-made assumptions are rarely considered, and their impacts on flood risk estimates are poorly understood. This study presents an alternate framework for rainfall frequency analysis that couples stochastic storm transposition (SST) with "storm catalogs" developed from a ten-year high-resolution (15-min, 1-km2) radar rainfall dataset for the region surrounding Charlotte, North Carolina, USA. The SST procedure involves spatial and temporal resampling from these storm catalogs to reconstruct the regional climatology of extreme rainfall. SST-based intensity-duration-frequency (IDF) estimates are driven by the spatial and temporal rainfall variability from weather radar observations, are tailored specifically to the chosen watershed, and do not require simplifying assumptions of storm structure. We are able to use the SST procedure to reproduce IDF estimates from conventional methods for four urban watersheds in Charlotte. We demonstrate that extreme rainfall can vary substantially in time and in space, with potentially important flood risk implications that cannot be assessed using conventional techniques. SST coupled with high-resolution radar rainfall fields represents a useful alternative to conventional design storms for flood risk assessment, the full advantages of which can be realized when the concept is extended to flood frequency analysis using a distributed hydrologic model.

  7. Urban pluvial flood prediction: a case study evaluating radar rainfall nowcasts and numerical weather prediction models as model inputs.

    PubMed

    Thorndahl, Søren; Nielsen, Jesper Ellerbæk; Jensen, David Getreuer

    2016-12-01

    Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events - especially in the future climate - it is valuable to be able to simulate these events numerically, both historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper, radar data observations with different spatial and temporal resolution, radar nowcasts of 0-2 h leadtime, and numerical weather models with leadtimes up to 24 h are used as inputs to an integrated flood and drainage systems model in order to investigate the relative difference between different inputs in predicting future floods. The system is tested on the small town of Lystrup in Denmark, which was flooded in 2012 and 2014. Results show it is possible to generate detailed flood maps in real-time with high resolution radar rainfall data, but rather limited forecast performance in predicting floods with leadtimes more than half an hour.

  8. Comparison of radar data versus rainfall data.

    PubMed

    Espinosa, B; Hromadka, T V; Perez, R

    2015-01-01

    Doppler radar data are increasingly used in rainfall-runoff synthesis studies, perhaps due to radar data availability, among other factors. However, the veracity of the radar data are often a topic of concern. In this paper, three Doppler radar outcomes developed by the United States National Weather Service at three radar sites are examined and compared to actual rain gage data for two separate severe storm events in order to assess accuracy in the published radar estimates of rainfall. Because the subject storms were very intense rainfall events lasting approximately one hour in duration, direct comparisons between the three radar gages themselves can be made, as well as a comparison to rain gage data at a rain gage location subjected to the same storm cells. It is shown that topographic interference with the radar outcomes can be a significant factor leading to differences between radar and rain gage readings, and that care is needed in calibrating radar outcomes using available rain gage data in order to interpolate rainfall estimates between rain gages using the spatial variation observed in the radar readings. The paper establishes and describes•the need for "ground-truthing" of radar data, and•possible errors due to topographic interference.

  9. Classifying Intensity and Area of Extreme Rainfall Events in Greater New York Area Using Weather Radar Data

    NASA Astrophysics Data System (ADS)

    Hamidi, A.; Devineni, N.; Booth, J. F.; Ferraro, R. R.; Khanbilvardi, R.

    2015-12-01

    Extreme rainfall events, specifically in urban areas, have dramatic impacts on society and can lead to loss of lives and properties. Despite these hazards, little is known about the city-scale variability of heavy rain events. In the current study, 13 years of gridded Stage IV radar data, 2002-2014, is employed to investigate the statistical properties of the spatiotemporal variability of simultaneous rainfall exceedances in Greater New York Area. The 95th percentile of each gridpoint's annual max intensity is considered as a threshold for storms. Then, multivariate k-means clustering is applied on extreme rainfall events' intensity and area exposure for each rainfall duration and season of occurrence. Comparison of timing indicates most of extreme rainfall events (more than 40%) are occurring in summer. Clustering analysis results show that for short rainfall duration, most of the study area is hit by high intensity-large area storm in warm seasons while in cold seasons rainfall intensity is low and the areal exposure is also low. In contrast, long rainfall duration follows an opposite spatiotemporal pattern. Resultant maps geo-reference the probability of occurrence of high-intensity large-area exposure storm over the study area. These maps can become inputs for design of hydraulic systems with the spatial and temporal resolution of 4km X 4km and 1-hour respectively which corresponds to the input radar data.

  10. Weather Radar Technology Development

    DTIC Science & Technology

    1990-08-15

    uelocitV WMs ) data processing systems such as NEXRAD to have a reliable technique for removing ambiguities due to velocity aliasing. Performance of many...intended for automated implementation on radar systems such as the NEXt generation weather RADar ( NEXRAD ) system. Several research areas were addressed...with Doppler radar will soon be realized with the deployment of the NEXRAD radar systems. Some of these large scale storms can have devastating wind

  11. Benefits and limitations of using the weather radar for the definition of rainfall thresholds for debris flows. Case study from Catalonia (Spain).

    NASA Astrophysics Data System (ADS)

    Abancó, C.; Hürlimann, M.; Sempere, D.; Berenguer, M.

    2012-04-01

    Torrential processes such as debris flows or hyperconcentrated flows are fast movements formed by a mix of water and different amounts of unsorted solid material. They occur in steep torrents and suppose a high risk for the human settlements. Rainfall is the most common triggering factor for debris flows. The rainfall threshold defines the rainfall conditions that, when reached or exceeded, are likely to provoke one or more events. Many different types of empirical rainfall thresholds for landslide triggering have been defined. Direct measurements of rainfall data are normally not available from a point next to or in the surroundings of the initiation area of the landslide. For this reason, most of the thresholds published for debris flows have been established by data measured at the nearest rain gauges (often located several km far from the landslide). Only in very few cases, the rainfall data to analyse the triggering conditions of the debris flows have been obtained by weather (Doppler) radar. Radar devices present certain limitations in mountainous regions due to undesired reboots, but their main advantage is that radar data can be obtained for any point of the territory. The objective of this work was to test the use of the weather radar data for the definition of rainfall thresholds for debris-flow triggering. Thus, rainfall data obtained from 3 to 5 rain gauges and from radar were compared for a dataset of events occurred in Catalonia (Spain). The goal was to determine in which cases the description of the rainfall episode (in particular the maximum intensity) had been more accurate. The analysed dataset consists of: 1) three events occurred in the Rebaixader debris-flow monitoring station (Axial Pyrenees) including two hyperconcentrated flows and one debris flow; 2) one debris-flow event occurred in the Port Ainé ski resort (Axial Pyrenees); 3) one debris-flow event in Montserrat (Mediterranean Coastal range). The comparison of the hyetographs from the

  12. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  13. Research relative to weather radar measurement techniques

    NASA Technical Reports Server (NTRS)

    Smith, Paul L.

    1992-01-01

    Research relative to weather radar measurement techniques, which involves some investigations related to measurement techniques applicable to meteorological radar systems in Thailand, is reported. A major part of the activity was devoted to instruction and discussion with Thai radar engineers, technicians, and meteorologists concerning the basic principles of radar meteorology and applications to specific problems, including measurement of rainfall and detection of wind shear/microburst hazards. Weather radar calibration techniques were also considered during this project. Most of the activity took place during two visits to Thailand, in December 1990 and February 1992.

  14. Assessing the role of spatial rainfall variability on watersheds response using weather radar A case study in the Gard region, France

    NASA Astrophysics Data System (ADS)

    Anggraheni, Evi; Payrastre, Olivier; Emmanuel, Isabelle; Andrieu, Herve

    2014-05-01

    The consideration of spatial rainfall variability in hydrological modeling is not only an important scientific issue but also, with the current development of high resolution rainfall data from weather radars, an increasing request from managers of sewerage networks and from flood forecasting services. Although the literature on this topic is already significant, at this time the conclusions remain contrasted. The impact of spatial rainfall variability on the hydrological responses appears to highly depend both on the organization of rainfall fields and on the watershed characteristics. The objective of the study presented here is to confirm and analyze the high impact of spatial rainfall variability in the specific context of flash floods. The case study presented is located in the Gard region in south east of France and focuses on four events which occurred on 13 different watersheds in 2008. The hydrological behaviors of these watersheds have been represented by the distributed rainfall - runoff model CINECAR, which already proved to well represent the hydrological responses in this region (Naulin et al., 2013). The influence of spatial rainfall variability has been studied here by considering two different rainfall inputs: radar data with a resolution of 1 km x 1 km and the spatial average rainfall over the catchment. First, the comparison between simulated and measured hydrographs confirms the good performances of the model for intense rainfall events, independently of the level of spatial rainfall variability of these events. Secondly, the simulated hydrographs obtained from radar data are taken as reference and compared to those obtained from the average rainfall inputs by computing two values: the time difference and the difference of magnitude between the simulated peaks discharge. The results highly depend on the rainfall event considered, and on the level of organization of the spatial rainfall variability. According to the model, the behavior of the

  15. Weather Radar Studies.

    DTIC Science & Technology

    1985-03-31

    National Center for Atmospheric Research JAWS program and the National Severe Storms Laboratory are being analyzed to develop low-altitude wind shear...public through low-altitude wind shear aviation weather products the National Technical Information Service, NEXR I turbulence., Springfield, VA 22161. 19...were analyzed preliminarily to determine wind shear characteristics in the Memphis area. Doppler weather radar data from the National Center for

  16. Probabilistic forecasts based on radar rainfall uncertainty

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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

  17. Weather Radar Studies.

    DTIC Science & Technology

    2014-09-26

    and Doppler weather radar data from the National Center for Atmospheric Research JAWS program and the National .Severe Storms Laboratory, are being...Atmospheric Research JAWS program and the National Severe Storms Laboratory, are being analyzed to develop low-altitude wind-shear detection algorithms...pictures, and dusted for fingerprints. The wind sensors, rain gauge, and antenna were destroyed but the DCP, solar panel, and other site components

  18. Weather Radar Studies

    DTIC Science & Technology

    1988-03-31

    Reflectivity Core Recognition 68 IV-10 Middle-Level Precursor Recognition 69 IV-l I Early Microburst Hazard Declaration 70 IV-12 Example of Results from...Denver Test Bed 106 V-I Selected Product Types 14 V-2 Encoded Map Size (in ELMs ) for Terminal Map Data Set 119 V-3 Encoded Map Size (in ELMs ) for En...Route Data Sets 119 V-4 Encoded Map Size (in ELMs ) for Terminal Map Data Set 125 xiii WEATHER RADAR STUDIES 1. INTRODUCTION The principal areas of

  19. Runoff Analysis Considering Orographical Features Using Dual Polarization Radar Rainfall

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  20. Aggregation and disaggregation of radar rainfall rates

    NASA Astrophysics Data System (ADS)

    Krebsbach, K.; Friederichs, P.

    2012-12-01

    Spatially distributed, high-resolution precipitation rates are key ingredients for modeling soil-vegetation processes, water and solute transports in mesoscale catchments, and for short-range weather prediction. The ultimate goal of our study is to develop a space-time, multilevel statistical model that merges rain radar measurements with other observations of precipitation. This is a challenging task since it aims at combining data sources with a variety of error structures, and temporal resolutions. E.g., in-situ measurements are quite accurate, but available only at sparse and irregularly distributed locations, whereas remote measurements cover complete areas but suffer from spatially and temporally inhomogeneous systematic errors. The first step towards such a space-time precipitation model is to develop a statistical model for precipitation based on radar measurements. Precipitation rates over a region of about 230× 230 km2 are provided by a composite of the two polarimetric X-band radars in Germany. The two radars are located in a distance of about 60 km in Bonn and Jülich, respectively. For the statistical model formulation we use a Gaussian Markov random field as underlying process. A Markov random field is a suitable model to account for spatial dependencies if the neighborhood can be reduced to a small region without losing information. This makes large data problems computationally feasible, since the neighborhood structure is given by a sparse precision matrix. Markov random fields are closely related to a graphical models. In processing the unadjusted radar rainfall rates, we follow D. Allcroft and C. Glasbey (2003)footnote{⪉bel{foot:1}David Allcroft and Chris Glasbey (2003). A latent Gaussian Markov Random Field model for spatiotemporal rainfall disaggregationJournal of the Royal Statistical Society: Series C (Applied Statistics), 52:487-498}. We start with a transformation of the precipitation rates to a truncated Gaussian distribution. The

  1. Hydrologic applications of weather radar

    NASA Astrophysics Data System (ADS)

    Seo, Dong-Jun; Habib, Emad; Andrieu, Hervé; Morin, Efrat

    2015-12-01

    By providing high-resolution quantitative precipitation information (QPI), weather radars have revolutionized hydrology in the last two decades. With the aid of GIS technology, radar-based quantitative precipitation estimates (QPE) have enabled routine high-resolution hydrologic modeling in many parts of the world. Given the ever-increasing need for higher-resolution hydrologic and water resources information for a wide range of applications, one may expect that the use of weather radar will only grow. Despite the tremendous progress, a number of significant scientific, technological and engineering challenges remain to realize its potential. New challenges are also emerging as new areas of applications are discovered, explored and pursued. The purpose of this special issue is to provide the readership with some of the latest advances, lessons learned, experiences gained, and science issues and challenges related to hydrologic applications of weather radar. The special issue features 20 contributions on various topics which reflect the increasing diversity as well as the areas of focus in radar hydrology today. The contributions may be grouped as follows: Radar QPE (Kwon et al.; Hall et al.; Chen and Chandrasekar; Seo and Krajewski; Sandford).

  2. Analysis of spatial variability of extreme rainfall at radar subpixel scale using IDF curves

    NASA Astrophysics Data System (ADS)

    Peleg, Nadav; Marra, Francesco; Fatichi, Simone; Paschalis, Athanasios; Molnar, Peter; Burlando, Paolo

    2016-04-01

    Extreme rainfall is quantified in engineering practice using Intensity-Duration-Frequency curves (IDFs) that are traditionally derived from rain-gauges and, more recently, also from weather radars. These instruments measure rainfall at different spatial scales: rain-gauge samples rainfall at the point scale while weather radar averages precipitation over a relatively large area, generally around 1 km2. As such, a radar derived IDF curve is representative of the mean areal rainfall over a given radar pixel and neglects the within-pixel rainfall variability. In this study, we quantify subpixel variability of extreme rainfall by using a novel space-time rainfall generator (STREAP model) that downscales in space the rainfall within a given radar pixel. The study was conducted using a long radar data record (23 years) and a very dense rain-gauge network in the Eastern Mediterranean area. Radar-IDF curves, together with an ensemble of point-based IDF curves representing the radar subpixel extreme rainfall variability, were developed fitting GEV distributions to annual rainfall maxima. It was found that the mean areal extreme rainfall derived from the radar underestimate most of the extreme values computed for point locations within the radar pixel. The subpixel variability of extreme rainfall was found to increase with longer return periods and shorter durations. For the longer return periods, a considerable enhancement of extreme rainfall variability was found when stochastic (natural) climate variability was taken into account. Bounding the range of the subpixel extreme rainfall derived from radar-IDF can be of major importance for applications that require very local estimates of rainfall extremes.

  3. Efficient Ways to Learn Weather Radar Polarimetry

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  4. Improvement of rainfall and flood forecasts by blending ensemble NWP rainfall with radar prediction considering orographic rainfall

    NASA Astrophysics Data System (ADS)

    Yu, Wansik; Nakakita, Eiichi; Kim, Sunmin; Yamaguchi, Kosei

    2015-12-01

    Many basins in Japan are characterized by steep mountainous regions, generating orographic rainfall events. Orographic rainfall may cause localized heavy rainfall to induce flash floods and sediment disasters. However, the accuracy of radar-based rainfall prediction was not enough because of the complex geographical pattern of the mountainous areas. In order to reduce damage due to localized heavy rainfall, characteristics of orographic rainfall must be identified into a short-term rainfall prediction procedure. The accuracy of radar-based rainfall prediction performs best for very short lead time, however the accuracy of radar prediction rapidly decreases with increasing lead times. At longer lead times, higher accuracy QPFs are produced by Numerical Weather Prediction (NWP) models, which solve the dynamics and physics of the atmosphere. This study proposes hybrid blending system of ensemble information from radar-based prediction and numerical weather prediction (NWP) to improve the accuracy of rainfall and flood forecasting. First, an improved radar image extrapolation method, which is comprised of the orographic rainfall identification and the error ensemble scheme, is introduced. Then, ensemble NWP outputs are updated based on mean bias of the error fields considering error structure. Finally, the improved radar-based prediction and updated NWP rainfall considering bias correction are blended dynamically with changing weight functions, which are computed from the expected skill of each radar prediction and updated NWP rainfall. The proposed method is verified temporally and spatially through a target event and is applied to the hybrid flood forecasting for updating with 1 h intervals. The newly proposed method shows sufficient reproducibility in peak discharge value, and could reduce the width of ensemble spread, which is expressed as the uncertainty, in the flood forecasting. Our study is carried out and verified using the largest flood event by typhoon

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  6. 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...

  7. Propagation of radar rainfall uncertainty in urban flood simulations

    NASA Astrophysics Data System (ADS)

    Liguori, Sara; Rico-Ramirez, Miguel

    2013-04-01

    , 2010. Review of the different sources of uncertainty in single polarization radar-based estimates of rainfall. Surveys in Geophysics 31: 107-129. [4] Rossa A, Liechti K, Zappa M, Bruen M, Germann U, Haase G, Keil C, Krahe P, 2011. The COST 731 Action: A review on uncertainty propagation in advanced hydrometeorological forecast systems. Atmospheric Research 100, 150-167. [5] Rossa A, Bruen M, Germann U, Haase G, Keil C, Krahe P, Zappa M, 2010. Overview and Main Results on the interdisciplinary effort in flood forecasting COST 731-Propagation of Uncertainty in Advanced Meteo-Hydrological Forecast Systems. Proceedings of Sixth European Conference on Radar in Meteorology and Hydrology ERAD 2010. [6] Germann U, Berenguer M, Sempere-Torres D, Zappa M, 2009. REAL - ensemble radar precipitation estimation for hydrology in a mountainous region. Quarterly Journal of the Royal Meteorological Society 135: 445-456. [8] Bowler NEH, Pierce CE, Seed AW, 2006. STEPS: a probabilistic precipitation forecasting scheme which merges and extrapolation nowcast with downscaled NWP. Quarterly Journal of the Royal Meteorological Society 132: 2127-2155. [9] Zappa M, Rotach MW, Arpagaus M, Dorninger M, Hegg C, Montani A, Ranzi R, Ament F, Germann U, Grossi G et al., 2008. MAP D-PHASE: real-time demonstration of hydrological ensemble prediction systems. Atmospheric Science Letters 9, 80-87. [10] Liguori S, Rico-Ramirez MA. Quantitative assessment of short-term rainfall forecasts from radar nowcasts and MM5 forecasts. Hydrological Processes, accepted article. DOI: 10.1002/hyp.8415 [11] Liguori S, Rico-Ramirez MA, Schellart ANA, Saul AJ, 2012. Using probabilistic radar rainfall nowcasts and NWP forecasts for flow prediction in urban catchments. Atmospheric Research 103: 80-95. [12] Harrison DL, Driscoll SJ, Kitchen M, 2000. Improving precipitation estimates from weather radar using quality control and correction techniques. Meteorological Applications 7: 135-144. [13] Harrison DL, Scovell RW, Kitchen

  8. Impacts of Characteristics of Errors in Radar Rainfall Estimates for Rainfall-Runoff Simulation

    NASA Astrophysics Data System (ADS)

    KO, D.; PARK, T.; Lee, T. S.; Shin, J. Y.; Lee, D.

    2015-12-01

    For flood prediction, weather radar has been commonly employed to measure the amount of precipitation and its spatial distribution. However, estimated rainfall from the radar contains uncertainty caused by its errors such as beam blockage and ground clutter. Even though, previous studies have been focused on removing error of radar data, it is crucial to evaluate runoff volumes which are influenced primarily by the radar errors. Furthermore, resolution of rainfall modeled by previous studies for rainfall uncertainty analysis or distributed hydrological simulation are quite coarse to apply to real application. Therefore, in the current study, we tested the effects of radar rainfall errors on rainfall runoff with a high resolution approach, called spatial error model (SEM). In the current study, the synthetic generation of random and cross-correlated radar errors were employed as SEM. A number of events for the Nam River dam region were tested to investigate the peak discharge from a basin according to error variance. The results indicate that the dependent error brings much higher variations in peak discharge than the independent random error. To further investigate the effect of the magnitude of cross-correlation between radar errors, the different magnitudes of spatial cross-correlations were employed for the rainfall-runoff simulation. The results demonstrate that the stronger correlation leads to higher variation of peak discharge and vice versa. We conclude that the error structure in radar rainfall estimates significantly affects on predicting the runoff peak. Therefore, the efforts must take into consideration on not only removing radar rainfall error itself but also weakening the cross-correlation structure of radar errors in order to forecast flood events more accurately. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which

  9. Enhanced Weather Radar (EWxR) System

    NASA Technical Reports Server (NTRS)

    Kronfeld, Kevin M. (Technical Monitor)

    2003-01-01

    An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

  10. Reducing Spaceborne-Doppler-Radar Rainfall-Velocity Error

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Im, Eastwood; Durden, Stephen L.

    2008-01-01

    A combined frequency-time (CFT) spectral moment estimation technique has been devised for calculating rainfall velocity from measurement data acquired by a nadir-looking spaceborne Doppler weather radar system. Prior spectral moment estimation techniques used for this purpose are based partly on the assumption that the radar resolution volume is uniformly filled with rainfall. The assumption is unrealistic in general but introduces negligible error in application to airborne radar systems. However, for spaceborne systems, the combination of this assumption and inhomogeneities in rainfall [denoted non-uniform beam filling (NUBF)] can result in velocity measurement errors of several meters per second. The present CFT spectral moment estimation technique includes coherent processing of a series of Doppler spectra generated in a standard manner from data over measurement volumes that are partially overlapping in the along-track direction. Performance simulation of this technique using high-resolution data from an airborne rain-mapping radar shows that a spaceborne Ku-band Doppler radar operating at signal-to-noise ratios greater than 10 dB can achieve root-mean-square accuracy between 0.5 and 0.6 m/s in vertical-velocity estimates.

  11. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  12. Radar rainfall estimation for the identification of debris-flow precipitation thresholds

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Nikolopoulos, Efthymios I.; Creutin, Jean-Dominique; Borga, Marco

    2014-05-01

    Identification of rainfall thresholds for the prediction of debris-flow occurrence is a common approach for warning procedures. Traditionally the debris-flow triggering rainfall is derived from the closest available raingauge. However, the spatial and temporal variability of intense rainfall on mountainous areas, where debris flows take place, may lead to large uncertainty in point-based estimates. Nikolopoulos et al. (2014) have shown that this uncertainty translates into a systematic underestimation of the rainfall thresholds, leading to a step degradation of the performances of the rainfall threshold for identification of debris flows occurrence under operational conditions. A potential solution to this limitation lies on use of rainfall estimates from weather radar. Thanks to their high spatial and temporal resolutions, these estimates offer the advantage of providing rainfall information over the actual debris flow location. The aim of this study is to analyze the value of radar precipitation estimations for the identification of debris flow precipitation thresholds. Seven rainfall events that triggered debris flows in the Adige river basin (Eastern Italian Alps) are analyzed using data from a dense raingauge network and a C-Band weather radar. Radar data are elaborated by using a set of correction algorithms specifically developed for weather radar rainfall application in mountainous areas. Rainfall thresholds for the triggering of debris flows are identified in the form of average intensity-duration power law curves using a frequentist approach by using both radar rainfall estimates and raingauge data. Sampling uncertainty associated to the derivation of the thresholds is assessed by using a bootstrap technique (Peruccacci et al. 2012). Results show that radar-based rainfall thresholds are largely exceeding those obtained by using raingauge data. Moreover, the differences between the two thresholds may be related to the spatial characteristics (i.e., spatial

  13. Close-range radar rainfall estimation and error analysis

    NASA Astrophysics Data System (ADS)

    van de Beek, C. Z.; Leijnse, H.; Hazenberg, P.; Uijlenhoet, R.

    2016-08-01

    Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are (1) radar calibration, (2) ground clutter, (3) wet-radome attenuation, (4) rain-induced attenuation, (5) vertical variability in rain drop size distribution (DSD), (6) non-uniform beam filling and (7) variations in DSD. This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1-2 km), where (4), (5) and (6) only play a minor role. Other important errors exist, like beam blockage, WLAN interferences and hail contamination and are briefly mentioned, but not considered in the analysis. A 3-day rainfall event (25-27 August 2010) that produced more than 50 mm of precipitation in De Bilt, the Netherlands, is analyzed using radar, rain gauge and disdrometer data. Without any correction, it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet-radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z-R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall-Palmer Z-R relation. Correcting for all of these effects has a large positive impact on the radar-derived precipitation estimates and yields a good match between radar QPE and gauge

  14. Research relative to weather radar measurement techniques

    NASA Technical Reports Server (NTRS)

    Smith, Paul L.

    1992-01-01

    This grant provides for some investigations related to weather radar measurement techniques applicable to meteorological radar systems in Thailand. Quality data are needed from those systems to support TRMM and other scientific investigations. Activities carried out during a trip to the radar facilities at Phuket are described.

  15. A study of radar backscattering from water surface in response to rainfall

    NASA Astrophysics Data System (ADS)

    Liu, Xinan; Zheng, Quanan; Liu, Ren; Wang, Dan; Duncan, James H.; Huang, Shih-Jen

    2016-03-01

    In this paper, radar backscattering from a water surface in response to rainfall was studied. The paper consists of two parts. First, the spatial characteristics of raindrops in rain fields were analyzed based on published data and the response of a water surface to rainfall was experimentally studied in the laboratory. Rain-generated surface features including stalks, crowns, ring waves, and secondary drops were measured. It was found that stalks and crowns are dominant in terms of their height and energy. Second, the radar signatures of a rainfall event simultaneously observed by C band ENVISAT (European satellite), ASAR (Advanced Synthetic Aperture Radar), and ground-based weather radar in the Northwest Pacific were investigated. The relationship between the radar return intensity extracted from the C band ASAR image and the reflectivity factor (rain rate) obtained from ground-based weather radar was analyzed. For light/moderate rain (with low reflectivity factors), the radar backscattering intensity increases as the reflectivity factor increases. For heavy rain (with high reflectivity factors), the radar backscattering intensity decreases as the reflectivity factor increases. The maximum radar backscattering intensity occurs at a reflectivity factor of 45 dBZ (with rain rate of 24 mm/h). It was found that the spaceborne radar backscattering intensity strongly correlates with the average distance between the stalks on the water surface in the rain field in a nonlinear manner. The physics of the radar signatures of the rain event are explored.

  16. Rainfall and Flood Frequency Analysis Using High-Resolution Radar Rainfall Fields and Stochastic Storm Transposition

    NASA Astrophysics Data System (ADS)

    Wright, Daniel; Smith, James; Baeck, Mary Lynn

    2013-04-01

    Spatial and temporal variability of rainfall fields, and their interactions with surface, subsurface, and drainage network properties, are important drivers of flood response. 'Design storms,' which are commonly used for flood risk assessment, however, are assumed to be uniform in space and either uniform or highly idealized in time. The impacts of these and other common assumptions on estimates of flood risk are poorly understood. We present an alternative framework for flood risk assessment based on stochastic storm transposition (SST). In this framework, "storm catalogs" are derived from a ten-year high-resolution (15-minute, 1 km2) bias-corrected radar rainfall dataset for the region surrounding Charlotte, North Carolina, USA. SST-based rainfall frequency analyses are developed by resampling from these storm catalogs to synthesize the regional climatology of extreme rainfall. SST-based intensity-frequency-duration (IFD) estimates are driven by the spatial and temporal rainfall variability from weather radar observations, are specifically tailored to the chosen catchment, and do not require simplifying assumptions of storm structure. We are able to use the SST procedure to reproduce IFD estimates from conventional methods for small urban catchments in Charlotte. We further demonstrate that extreme rainfall can vary substantially in time and in space, with important flood risk implications that cannot be assessed using conventional techniques. When coupled with a physics-based distributed hydrologic model, the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model, SST enables us to examine the full impact of spatial and temporal rainfall variability on flood response and flood frequency. The interactions of extreme rainfall with spatially distributed land use, soil properties, and stormwater management infrastructure are assessed for several nested urban catchments in Charlotte. Results suggest that these interactions, which cannot be fully accounted for

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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

  18. Using TRMM and GPM precipitation radar for calibration of weather radars in the Philippines

    NASA Astrophysics Data System (ADS)

    Crisologo, Irene; Bookhagen, Bodo; Smith, Taylor; Heistermann, Maik

    2016-04-01

    Torrential and sustained rainfall from tropical cyclones, monsoons, and thunderstorms frequently impact the Philippines. In order to predict, assess, and measure storm impact, it is imperative to have a reliable and accurate monitoring system in place. In 2011, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) established a weather radar network of ten radar devices, eight of which are single-polarization S-band radars and two dual-polarization C-band radars. Because of a low-density hydrometeorological monitoring networks in the Philippines, calibration of weather radars becomes a challenging, but important task. In this study, we explore the potential of scrutinizing the calibration of ground radars by using the observations from the Tropical Rainfall Measuring Mission (TRMM). For this purpose, we compare different TRMM level 1 and 2 orbital products from overpasses over the Philippines, and compare these products to reflectivities observed by the Philippine ground radars. Differences in spatial resolution are addressed by computing adequate zonal statistics of the local radar bins located within the corresponding TRMM cell in space and time. The wradlib package (Heistermann et al. 2013; Heistermann et al. 2015) is used to process the data from the Subic S-band single-polarization weather radar. These data will be analyzed in conjunction with TRMM data for June to August 2012, three months of the wet season. This period includes the enhanced monsoon of 2012, locally called Habagat 2012, which brought sustained intense rainfall and massive floods in several parts of the country including the most populated city of Metro Manila. References Heistermann, M., Jacobi, S., Pfaff, T. (2013): Technical Note: An open source library for processing weather radar data (wradlib). Hydrol. Earth Syst. Sci., 17, 863-871, doi: 10.5194/hess-17-863-2013. Heistermann, M., S. Collis, M. J. Dixon, S. Giangrande, J. J. Helmus, B. Kelley, J

  19. Improving radar rainfall estimation by merging point rainfall measurements within a model combination framework

    NASA Astrophysics Data System (ADS)

    Hasan, Mohammad Mahadi; Sharma, Ashish; Mariethoz, Gregoire; Johnson, Fiona; Seed, Alan

    2016-11-01

    While the value of correcting raw radar rainfall estimates using simultaneous ground rainfall observations is well known, approaches that use the complete record of both gauge and radar measurements to provide improved rainfall estimates are much less common. We present here two new approaches for estimating radar rainfall that are designed to address known limitations in radar rainfall products by using a relatively long history of radar reflectivity and ground rainfall observations. The first of these two approaches is a radar rainfall estimation algorithm that is nonparametric by construction. Compared to the traditional gauge adjusted parametric relationship between reflectivity (Z) and ground rainfall (R), the suggested new approach is based on a nonparametric radar rainfall estimation method (NPR) derived using the conditional probability distribution of reflectivity and gauge rainfall. The NPR method is applied to the densely gauged Sydney Terrey Hills radar network, where it reduces the RMSE in rainfall estimates by 10%, with improvements observed at 90% of the gauges. The second of the two approaches is a method to merge radar and spatially interpolated gauge measurements. The two sources of information are combined using a dynamic combinatorial algorithm with weights that vary in both space and time. The weight for any specific period is calculated based on the error covariance matrix that is formulated from the radar and spatially interpolated rainfall errors of similar reflectivity periods in a cross-validation setting. The combination method reduces the RMSE by about 20% compared to the traditional Z-R relationship method, and improves estimates compared to spatially interpolated point measurements in sparsely gauged areas.

  20. A New Approach For Reducing The Uncertainty In Radar Rainfall Estimation Procedures

    NASA Astrophysics Data System (ADS)

    Chumchean, S.; Sharma, A.

    The weather radar provides a convenient means for measuring rainfall in space and time. However, its use as a rainfall measuring device is limited due to the poor accu- racy of algorithms used to convert the measured reflectivity to ground rainfall. While this accuracy can be acceptable in situations where the catchment is large and ground measurements few, the use of radar based rainfall observations can lead to signifi- cant errors in small catchments located far from the radar site. This study aims to identify some of the reasons behind the limited accuracy of radar rainfall estimation algorithms, and proposes a method that addresses some of the factors responsible. The accuracy of weather radars is effected by a number of factors, not all of which are considered in the algorithms used. Some of these are: (a) mis-specification of the relationship between reflectivity and rainfall through the use of an improperly speci- fied equation, (b) nonstationarity in measured reflectivity values due to changes in the rainfall drop size distribution, (c) an inability to convert the reflectivity measured at an elevation above ground to the rainfall at ground level, and, (d) a reduction in the reli- ability associated with measured reflectivity with increase in distance from the radar, a result of the radar emitted power being shared over an increasing volume of air. The above factors can be addressed by either formulating a relationship that is stable and consistent, or using a quantile matching approach called the Probability Matching Method (PMM) which is helpful when the relationship is difficult to specify. How- ever, for either method to be useful, the measured reflectivity must be stationary, or, must bear the same relation with rainfall irrespective of factors such as changes in storm type or distance from the radar. Another cause of nonstationarity in the mea- sured reflectivity values is use of measurements that vary in accuracy depending on their distance from the

  1. On the study of radar backscattering of ocean surface in response to rainfall

    NASA Astrophysics Data System (ADS)

    Liu, Xinan; Zheng, Quanan; Liu, Ren; Duncan, James H.

    2013-11-01

    A model of radar backscattering from the ocean surface in response to rainfall is developed. The model shows that the radar return intensity is a function of the wavelength and incident angle of the radar waves and the rain rate. The model explains the differences between the radar response to rain rate simultaneously observed by C-band ASAR and ground-based weather radar. An experiment on the simultaneous measurements of the characteristics of the ocean surface in response to rainfall and its radar back-scatter is performed in the laboratory. The experiment is carried out in a water pool that is 1.22 m by 1.22 m with a water depth of 0.3 m. Artificial rainfall is generated from an array of hypodermic needles. The surface characteristics including crowns, stalks and ring waves are measured with a cinematic Laser-Induced-Florescence (LIF) technique while secondary droplets are measured with a shadowgraph technique. The radar backscattering signal is recorded with a dual-polarized, ultra-wide band radar. The frequency dependence and polarization of the radar signatures due to the surface features are discussed. The work is supported by National Science Foundations, Division of Ocean Science.

  2. Comparison of radar and raingauge measurements during heavy rainfall.

    PubMed

    Einfalt, T; Jessen, M; Mehlig, B

    2005-01-01

    Five heavy small-scale rainfall events in North Rhine-Westphalia (Germany) were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be very difficult in the vicinity of heavy local rain cells. For the five affected regions the precipitation was quantified in the form of areal time series and cumulated radar images. As further result of this project, the spatial extent of the precipitation fields was identified and compared with radar and raingauge data.

  3. NEXRAD - An advanced Doppler weather radar system

    NASA Astrophysics Data System (ADS)

    Durham, A. F.

    The WSR-57 system, which was first placed into operation in 1957, forms the backbone of the current radar observation network of the National Weather Service. However, in connection with its age, it has become increasingly difficult and expensive to maintain this system. The present investigation is concerned with the replacement of the WSR-57 by a new system which incorporates important advances made in radar technology since the 1950s. The new system considered, called the Next Generation Weather Radar (NEXRAD) makes use of highly automated Doppler techniques to measure the radial velocity of air movement within the internal structure of a storm system. Attention is given to background regarding the NEXRAD system development, the four phases of the NEXRAD program, NEXRAD system capabilities, operational (display) products, and questions of siting.

  4. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

  5. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

  6. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

  7. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

  8. 14 CFR 121.357 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... § 121.357 Airborne weather radar equipment requirements. (a) No person may operate any transport... December 31, 1964, unless approved airborne weather radar equipment has been installed in the airplane....

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

    PubMed

    Collier, C G

    2002-07-15

    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.

  10. Uncertainty Analysis of Radar and Gauge Rainfall Estimates in the Russian River Basin

    NASA Astrophysics Data System (ADS)

    Cifelli, R.; Chen, H.; Willie, D.; Reynolds, D.; Campbell, C.; Sukovich, E.

    2013-12-01

    Radar Quantitative Precipitation Estimation (QPE) has been a very important application of weather radar since it was introduced and made widely available after World War II. Although great progress has been made over the last two decades, it is still a challenging process especially in regions of complex terrain such as the western U.S. It is also extremely difficult to make direct use of radar precipitation data in quantitative hydrologic forecasting models. To improve the understanding of rainfall estimation and distributions in the NOAA Hydrometeorology Testbed in northern California (HMT-West), extensive evaluation of radar and gauge QPE products has been performed using a set of independent rain gauge data. This study focuses on the rainfall evaluation in the Russian River Basin. The statistical properties of the different gridded QPE products will be compared quantitatively. The main emphasis of this study will be on the analysis of uncertainties of the radar and gauge rainfall products that are subject to various sources of error. The spatial variation analysis of the radar estimates is performed by measuring the statistical distribution of the radar base data such as reflectivity and by the comparison with a rain gauge cluster. The application of mean field bias values to the radar rainfall data will also be described. The uncertainty analysis of the gauge rainfall will be focused on the comparison of traditional kriging and conditional bias penalized kriging (Seo 2012) methods. This comparison is performed with the retrospective Multisensor Precipitation Estimator (MPE) system installed at the NOAA Earth System Research Laboratory. The independent gauge set will again be used as the verification tool for the newly generated rainfall products.

  11. Rainfall Measurement with a Ground Based Dual Frequency Radar

    NASA Technical Reports Server (NTRS)

    Takahashi, Nobuhiro; Horie, Hiroaki; Meneghini, Robert

    1997-01-01

    Dual frequency methods are one of the most useful ways to estimate precise rainfall rates. However, there are some difficulties in applying this method to ground based radars because of the existence of a blind zone and possible error in the radar calibration. Because of these problems, supplemental observations such as rain gauges or satellite link estimates of path integrated attenuation (PIA) are needed. This study shows how to estimate rainfall rate with a ground based dual frequency radar with rain gauge and satellite link data. Applications of this method to stratiform rainfall is also shown. This method is compared with single wavelength method. Data were obtained from a dual frequency (10 GHz and 35 GHz) multiparameter radar radiometer built by the Communications Research Laboratory (CRL), Japan, and located at NASA/GSFC during the spring of 1997. Optical rain gauge (ORG) data and broadcasting satellite signal data near the radar t location were also utilized for the calculation.

  12. Radar Rainfall Estimation using a Quadratic Z-R equation

    NASA Astrophysics Data System (ADS)

    Hall, Will; Rico-Ramirez, Miguel Angel; Kramer, Stefan

    2016-04-01

    The aim of this work is to test a method that enables the input of event based drop size distributions to alter a quadratic reflectivity (Z) to rainfall (R) equation that is limited by fixed upper and lower points. Results will be compared to the Marshall-Palmer Z-R relation outputs and validated by a network of gauges and a single polarisation weather radar located close to Essen, Germany. The time window over which the drop size distribution measurements will be collected is varied to note any effect on the generated quadratic Z-R relation. The new quadratic algorithm shows some distinct improvement over the Marshall-Palmer relationship through multiple events. The inclusion of a minimum number of Z-R points helped to decrease the associated error by defaulting back to the Marshall-Palmer equation if the limit was not reached. More research will be done to discover why the quadratic performs poorly in some events as there appears to be little correlation between number of drops or mean rainfall amount and the associated error. In some cases it seems the spatial distribution of the disdrometers has a significant effect as a large percentage of the rain bands pass to the north of two of the three disdrometers, frequently in a slightly north-easterly direction. However during widespread precipitation events the new algorithm works very well with reductions compared to the Marshall-Palmer relation.

  13. Radar rainfall estimation of stratiform winter precipitation in the Belgian Ardennes

    NASA Astrophysics Data System (ADS)

    Hazenberg, P.; Leijnse, H.; Uijlenhoet, R.

    2010-12-01

    Radars are known for their ability to obtain a wealth of information about spatial storm field characteristics. Unfortunately, rainfall estimates obtained by this instrument are known to be affected by multiple sources of error. Especially for stratiform precipitation systems, the quality of radar rainfall estimates starts to decrease at relatively close ranges. In the current study the hydrological potential of weather radar is analyzed during a winter half-year for the hilly region of the Belgian Ardennes. A correction algorithm is proposed which corrects the radar data for errors related to attenuation, ground clutter, anomalous propagation, the vertical profile of reflectivity (VPR) and advection. No final bias correction with respect to rain gauge data was implemented, because that does not add to a better understanding of the quality of the radar. The impact of the different corrections is then being compared to rainfall information sampled by 42 hourly rain gauges. The largest improvement in the quality of the radar data is obtained by correcting for ground clutter. The impact of VPR correction and advection depends on the spatial variability and velocity of the precipitation system. Overall during the winter period, the radar underestimates the amount of precipitation as compared to the rain gauges. Remaining differences between both devices can be attributed to spatial and temporal variability in the type of precipitation which has not been taken into account.

  14. Development of Radar-Satellite Blended QPF (Quantitative Precipitation Forecast) Technique for heavy rainfall

    NASA Astrophysics Data System (ADS)

    Jang, Sangmin; Yoon, Sunkwon; Rhee, Jinyoung; Park, Kyungwon

    2016-04-01

    Due to the recent extreme weather and climate change, a frequency and size of localized heavy rainfall increases and it may bring various hazards including sediment-related disasters, flooding and inundation. To prevent and mitigate damage from such disasters, very short range forecasting and nowcasting of precipitation amounts are very important. Weather radar data very useful in monitoring and forecasting because weather radar has high resolution in spatial and temporal. Generally, extrapolation based on the motion vector is the best method of precipitation forecasting using radar rainfall data for a time frame within a few hours from the present. However, there is a need for improvement due to the radar rainfall being less accurate than rain-gauge on surface. To improve the radar rainfall and to take advantage of the COMS (Communication, Ocean and Meteorological Satellite) data, a technique to blend the different data types for very short range forecasting purposes was developed in the present study. The motion vector of precipitation systems are estimated using 1.5km CAPPI (Constant Altitude Plan Position Indicator) reflectivity by pattern matching method, which indicates the systems' direction and speed of movement and blended radar-COMS rain field is used for initial data. Since the original horizontal resolution of COMS is 4 km while that of radar is about 1 km, spatial downscaling technique is used to downscale the COMS data from 4 to 1 km pixels in order to match with the radar data. The accuracies of rainfall forecasting data were verified utilizing AWS (Automatic Weather System) observed data for an extreme rainfall occurred in the southern part of Korean Peninsula on 25 August 2014. The results of this study will be used as input data for an urban stream real-time flood early warning system and a prediction model of landslide. Acknowledgement This research was supported by a grant (13SCIPS04) from Smart Civil Infrastructure Research Program funded by

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

    NASA Astrophysics Data System (ADS)

    Aghakouchak, A.; Habib, E.

    2008-05-01

    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.

  16. A radar backscattering mechanism of ocean surface in response to rainfall

    NASA Astrophysics Data System (ADS)

    Liu, Xinan; Zheng, Quanan; Liu, Ren; Duncan, James H.

    2012-11-01

    The characteristics of ocean surface in response to rainfall and its radar back-scatter are simultaneously measured in laboratory. The experiment is carried out in a water pool that is 1.22 m by 1.22 m with a water depth of 0.3 m. Artificial rainfall is generated from an array of hypodermic needles. The surface characteristics including crowns, stalks, secondary droplets and ring waves are measured with a cinematic Laser-Induced-Florescence (LIF) technique. Our experimental results show that impinging raindrops on the water surface generate various water surface structures with different relative sizes. Among them stalks and crowns comprise the dominant radar backscattering. On the basis of these laboratory experiments and theories of radar scattering from a rough surface, a near-resonance radar backscattering model for quantifying the dependence of the radar return intensity on rain rate on the ocean surface is developed. The model explains the radar response to rain rate simultaneously observed by C-band ASAR and ground-based weather radar. The physical model provides reasonable mechanisms to explain the frequency dependence and polarization behavior of radar signatures from rain cells on the ocean surface. This work is supported by the National Science Foundation, Division of Ocean Sciences under grant OCE962107.

  17. 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. ...

  18. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  19. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  20. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  1. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  2. 14 CFR 125.223 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... Equipment Requirements § 125.223 Airborne weather radar equipment requirements. (a) No person may operate an airplane governed by this part in passenger-carrying operations unless approved airborne weather...

  3. The potential of urban rainfall monitoring with crowdsourced automatic weather stations in Amsterdam

    NASA Astrophysics Data System (ADS)

    de Vos, Lotte; Leijnse, Hidde; Overeem, Aart; Uijlenhoet, Remko

    2017-02-01

    The high density of built-up areas and resulting imperviousness of the land surface makes urban areas vulnerable to extreme rainfall, which can lead to considerable damage. In order to design and manage cities to be able to deal with the growing number of extreme rainfall events, rainfall data are required at higher temporal and spatial resolutions than those needed for rural catchments. However, the density of operational rainfall monitoring networks managed by local or national authorities is typically low in urban areas. A growing number of automatic personal weather stations (PWSs) link rainfall measurements to online platforms. Here, we examine the potential of such crowdsourced datasets for obtaining the desired resolution and quality of rainfall measurements for the capital of the Netherlands. Data from 63 stations in Amsterdam (˜ 575 km2) that measure rainfall over at least 4 months in a 17-month period are evaluated. In addition, a detailed assessment is made of three Netatmo stations, the largest contributor to this dataset, in an experimental setup. The sensor performance in the experimental setup and the density of the PWS network are promising. However, features in the online platforms, like rounding and thresholds, cause changes from the original time series, resulting in considerable errors in the datasets obtained. These errors are especially large during low-intensity rainfall, although they can be reduced by accumulating rainfall over longer intervals. Accumulation improves the correlation coefficient with gauge-adjusted radar data from 0.48 at 5 min intervals to 0.60 at hourly intervals. Spatial rainfall correlation functions derived from PWS data show much more small-scale variability than those based on gauge-adjusted radar data and those found in similar research using dedicated rain gauge networks. This can largely be attributed to the noise in the PWS data resulting from both the measurement setup and the processes occurring in the data

  4. On Radar Rainfall, Catchment Runoff and the Response Scale

    NASA Astrophysics Data System (ADS)

    Morin, E.; Goodrich, D. C.; Gao, X.; Sorooshian, S.

    2001-12-01

    The general research hypothesis is that: "a rainfall event, extreme at a specific scale, has the potential to generate an extreme runoff event in a catchment, which characterized by this response scale". In the presented study, which is a first step in testing this hypothesis, we examine if catchments have a stable response scale in the above context. For that purpose, we compare maximum storm rainfall intensities at different time and space scales with runoff peak discharges in order to determine at what scale these two variables are best related to each other. Three types of rainfall variable are tested: 1) gage rainfall intensity, 2) radar rainfall intensity, and 3) radar reflectivity. Initial results are available for the Walnut Gulch Experimental Catchment, a 150-km2 semi-arid catchment, located in southern Arizona. The catchment is well equipped with dense networks of rainfall and runoff gages. Radar data are also available for the catchment from the Tucson NEXRAD system. Preliminary results indicate a response scale in the order of 6-km and 2-hours for the 150-km2 catchment and for the 126- and 94-km2 sub-catchments. The response scale of a 25-km2 sub-catchment is reduced to 1-km and 20-minutes. The three types of rainfall variable tested point to the same response scale. As mentioned, the above results are initial and based on a limited number of events. We are investigating this hypothesis on a larger number of events as well as additional catchments.

  5. Stochastic simulation experiment to assess radar rainfall retrieval uncertainties associated with attenuation and its correction

    NASA Astrophysics Data System (ADS)

    Uijlenhoet, R.; Berne, A.

    2008-03-01

    As rainfall constitutes the main source of water for the terrestrial hydrological processes, accurate and reliable measurement and prediction of its spatial and temporal distribution over a wide range of scales is an important goal for hydrology. We investigate the potential of ground-based weather radar to provide such measurements through a theoretical analysis of some of the associated observation uncertainties. A stochastic model of range profiles of raindrop size distributions is employed in a Monte Carlo simulation experiment to investigate the rainfall retrieval uncertainties associated with weather radars operating at X-, C-, and S-band. We focus in particular on the errors and uncertainties associated with rain-induced signal attenuation and its correction for incoherent, non-polarimetric, single-frequency, operational weather radars. The performance of two attenuation correction schemes, the (forward) Hitschfeld-Bordan algorithm and the (backward) Marzoug-Amayenc algorithm, is analyzed for both moderate (assuming a 50 km path length) and intense Mediterranean rainfall (for a 30 km path). A comparison shows that the backward correction algorithm is more stable and accurate than the forward algorithm (with a bias in the order of a few percent for the former, compared to tens of percent for the latter), provided reliable estimates of the total path-integrated attenuation are available. Moreover, the bias and root mean square error associated with each algorithm are quantified as a function of path-averaged rain rate and distance from the radar in order to provide a plausible order of magnitude for the uncertainty in radar-retrieved rain rates for hydrological applications.

  6. A New Method for Radar Rainfall Estimation Using Merged Radar and Gauge Derived Fields

    NASA Astrophysics Data System (ADS)

    Hasan, M. M.; Sharma, A.; Johnson, F.; Mariethoz, G.; Seed, A.

    2014-12-01

    Accurate estimation of rainfall is critical for any hydrological analysis. The advantage of radar rainfall measurements is their ability to cover large areas. However, the uncertainties in the parameters of the power law, that links reflectivity to rainfall intensity, have to date precluded the widespread use of radars for quantitative rainfall estimates for hydrological studies. There is therefore considerable interest in methods that can combine the strengths of radar and gauge measurements by merging the two data sources. In this work, we propose two new developments to advance this area of research. The first contribution is a non-parametric radar rainfall estimation method (NPZR) which is based on kernel density estimation. Instead of using a traditional Z-R relationship, the NPZR accounts for the uncertainty in the relationship between reflectivity and rainfall intensity. More importantly, this uncertainty can vary for different values of reflectivity. The NPZR method reduces the Mean Square Error (MSE) of the estimated rainfall by 16 % compared to a traditionally fitted Z-R relation. Rainfall estimates are improved at 90% of the gauge locations when the method is applied to the densely gauged Sydney Terrey Hills radar region. A copula based spatial interpolation method (SIR) is used to estimate rainfall from gauge observations at the radar pixel locations. The gauge-based SIR estimates have low uncertainty in areas with good gauge density, whilst the NPZR method provides more reliable rainfall estimates than the SIR method, particularly in the areas of low gauge density. The second contribution of the work is to merge the radar rainfall field with spatially interpolated gauge rainfall estimates. The two rainfall fields are combined using a temporally and spatially varying weighting scheme that can account for the strengths of each method. The weight for each time period at each location is calculated based on the expected estimation error of each method

  7. An integrated approach for identifying homogeneous regions of extreme rainfall events and estimating IDF curves in Southern Ontario, Canada: Incorporating radar observations

    NASA Astrophysics Data System (ADS)

    Paixao, Edson; Mirza, M. Monirul Qader; Shephard, Mark W.; Auld, Heather; Klaassen, Joan; Smith, Graham

    2015-09-01

    Reliable extreme rainfall information is required for many applications including infrastructure design, management of water resources, and planning for weather-related emergencies in urban and rural areas. In this study, in situ TBRG sub-daily rainfall rate observations have been supplemented with weather radar information to better capture the spatial and temporal variability of heavy rainfall events regionally. Comparison of extreme rainfall events show that the absolute differences between the rain gauge and radar generally increase with increasing rainfall. Better agreement between the two observations is found when comparing the collocated radar and TBRG annual maximum values. The median difference is <18% for the annual maximum rainfall values ⩽50 mm. The median of difference of IDF estimates obtained through the Gumbel distribution for 10-year return period values computed from TBRG and radar are also found to be 4%. The overall results of this analysis demonstrates the potential value of incorporating remotely sensed radar with traditional point source TBRG network observations to provide additional insight on extreme rainfall events regionally, especially in terms of identifying homogeneous regions of extreme rainfall. The radar observations are particularly useful in areas where there is insufficient TBRG station density to statistically capture the extreme rainfall events.

  8. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne...

  9. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne...

  10. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne...

  11. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne...

  12. 14 CFR 135.175 - Airborne weather radar equipment requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airborne weather radar equipment... Aircraft and Equipment § 135.175 Airborne weather radar equipment requirements. (a) No person may operate a large, transport category aircraft in passenger-carrying operations unless approved airborne...

  13. Long-term accounting for raindrop size distribution variations improves quantitative precipitation estimation by weather radar

    NASA Astrophysics Data System (ADS)

    Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

    2016-04-01

    Weather radars provide information on the characteristics of precipitation at high spatial and temporal resolution. Unfortunately, rainfall measurements by radar are affected by multiple error sources. The current study is focused on the impact of variations of the raindrop size distribution on radar rainfall estimates. Such variations lead to errors in the estimated rainfall intensity (R) and specific attenuation (k) when using fixed relations for the conversion of the observed reflectivity (Z) into R and k. For non-polarimetric radar, this error source has received relatively little attention compared to other error sources. We propose to link the parameters of the Z-R and Z-k relations directly to those of the normalized gamma DSD. The benefit of this procedure is that it reduces the number of unknown parameters. In this work, the DSD parameters are obtained using 1) surface observations from a Parsivel and Thies LPM disdrometer, and 2) a Monte Carlo optimization procedure using surface rain gauge observations. The impact of both approaches for a given precipitation type is assessed for 45 days of summertime precipitation observed in The Netherlands. Accounting for DSD variations using disdrometer observations leads to an improved radar QPE product as compared to applying climatological Z-R and Z-k relations. This especially holds for situations where widespread stratiform precipitation is observed. The best results are obtained when the DSD parameters are optimized. However, the optimized Z-R and Z-k relations show an unrealistic variability that arises from uncorrected error sources. As such, the optimization approach does not result in a realistic DSD shape but instead also accounts for uncorrected error sources resulting in the best radar rainfall adjustment. Therefore, to further improve the quality of preciptitation estimates by weather radar, usage should either be made of polarimetric radar or by extending the network of disdrometers.

  14. Influence of small scale rainfall variability on standard comparison tools between radar and rain gauge data

    NASA Astrophysics Data System (ADS)

    Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel; Schellart, Alma; Berne, Alexis; Lovejoy, Shaun

    2014-03-01

    Rain gauges and weather radars do not measure rainfall at the same scale; roughly 20 cm for the former and 1 km for the latter. This significant scale gap is not taken into account by standard comparison tools (e.g. cumulative depth curves, normalized bias, RMSE) despite the fact that rainfall is recognized to exhibit extreme variability at all scales. In this paper we suggest to revisit the debate of the representativeness of point measurement by explicitly modelling small scale rainfall variability with the help of Universal Multifractals. First the downscaling process is validated with the help of a dense networks of 16 disdrometers (in Lausanne, Switzerland), and one of 16 rain gauges (Bradford, United Kingdom) both located within a 1 km2 area. Second this downscaling process is used to evaluate the impact of small scale (i.e. sub-radar pixel) rainfall variability on the standard indicators. This is done with rainfall data from the Seine-Saint-Denis County (France). Although not explaining all the observed differences, it appears that this impact is significant which suggests changing some usual practice.

  15. Comparison of rain gauge and radar data as input to an urban rainfall-runoff model.

    PubMed

    Quirmbach, M; Schultz, G A

    2002-01-01

    This paper presents an application of radar data (DX-product of the German Weather Service) with a high resolution in space (1 degree x 1 km) and time (delta t = 5 minutes) in urban hydrology. The radar data and data of rain gauges with different locations in the test catchment were compared concerning their suitability as input into an urban rainfall-runoff model. In order to evaluate the accuracy of model simulation results, five evaluation criteria have been specified which are relevant for an efficient management of sewer systems and wastewater treatment plants. The results demonstrate that radar data should be used in urban hydrology if distances > 4 km between rain gauge and catchment exist and for catchments with a density of rain gauges smaller than 1 rain gauge per 16 km2.

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

    NASA Astrophysics Data System (ADS)

    Haiguang, Zhou

    2010-05-01

    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-β-scale convective system (MβCS) and the meso-γ-scale system located on the MβCS played an important role on this heavy rainfall. The meso-β-scale convective cloud has high precipitation efficiency. The dual-Doppler retrieved wind reveals that the heavy rainfall was caused by the meso-β-scale shear line and the meso-β-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 MβCS. 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).

  17. Simulation of a weather radar display for over-water airborne radar approaches

    NASA Technical Reports Server (NTRS)

    Clary, G. R.

    1983-01-01

    Airborne radar approach (ARA) concepts are being investigated as a part of NASA's Rotorcraft All-Weather Operations Research Program on advanced guidance and navigation methods. This research is being conducted using both piloted simulations and flight test evaluations. For the piloted simulations, a mathematical model of the airborne radar was developed for over-water ARAs to offshore platforms. This simulated flight scenario requires radar simulation of point targets, such as oil rigs and ships, distributed sea clutter, and transponder beacon replies. Radar theory, weather radar characteristics, and empirical data derived from in-flight radar photographs are combined to model a civil weather/mapping radar typical of those used in offshore rotorcraft operations. The resulting radar simulation is realistic and provides the needed simulation capability for ongoing ARA research.

  18. Evaluation of Various Radar Data Quality Control Algorithms Based on Accumulated Radar Rainfall Statistics

    NASA Technical Reports Server (NTRS)

    Robinson, Michael; Steiner, Matthias; Wolff, David B.; Ferrier, Brad S.; Kessinger, Cathy; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The primary function of the TRMM Ground Validation (GV) Program is to create GV rainfall products that provide basic validation of satellite-derived precipitation measurements for select primary sites. A fundamental and extremely important step in creating high-quality GV products is radar data quality control. Quality control (QC) processing of TRMM GV radar data is based on some automated procedures, but the current QC algorithm is not fully operational and requires significant human interaction to assure satisfactory results. Moreover, the TRMM GV QC algorithm, even with continuous manual tuning, still can not completely remove all types of spurious echoes. In an attempt to improve the current operational radar data QC procedures of the TRMM GV effort, an intercomparison of several QC algorithms has been conducted. This presentation will demonstrate how various radar data QC algorithms affect accumulated radar rainfall products. In all, six different QC algorithms will be applied to two months of WSR-88D radar data from Melbourne, Florida. Daily, five-day, and monthly accumulated radar rainfall maps will be produced for each quality-controlled data set. The QC algorithms will be evaluated and compared based on their ability to remove spurious echoes without removing significant precipitation. Strengths and weaknesses of each algorithm will be assessed based on, their abilit to mitigate both erroneous additions and reductions in rainfall accumulation from spurious echo contamination and true precipitation removal, respectively. Contamination from individual spurious echo categories will be quantified to further diagnose the abilities of each radar QC algorithm. Finally, a cost-benefit analysis will be conducted to determine if a more automated QC algorithm is a viable alternative to the current, labor-intensive QC algorithm employed by TRMM GV.

  19. Design and Implementation of an Active Calibration System for Weather Radars

    DTIC Science & Technology

    2008-09-01

    Chassis( FPGAs ) and the LabVIEW FPGA module for programming commands that can be auto-compiled into VHDL for the CompactRIO Chassis( FPGAs ). 129 APPENDIX... sources , gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden...unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Weather radars permit meteorological quantities such as rainfall rate and wind

  20. Hydro-NEXRAD radar database: A community resource for rainfall studies

    NASA Astrophysics Data System (ADS)

    Kruger, A.; Krajewski, W. F.; Goska, R.; Domaszczynski, P.; Gunyon, C.; Smith, J. A.; Baeck, M. L.

    2009-04-01

    Hydro-NEXRAD is a software system with web-based user interface for obtaining historical customized NEXRAD-based radar-rainfall maps (products) from some 40 WSR-88D radars covering mainly the central and eastern U.S. These products have increased spatial and temporal resolution in comparison to the operational products available from the US National Weather Service. Rainfall researchers and hydrologists can request customized products by selecting various algorithmic modules and parameter values. The produced rainfall maps can be projected on a grid of choice. The output is formatted for ingest by geographic information systems and mapping software. The authors present the system architecture, the database extent and the possibilities of including additional algorithms in the future versions. They illustrate the utility of the software with several applications where side-by-side comparisons of various products allow studies of uncertainty propagation and sensitivity analysis. One of the comparisons presented involves the NWS products obtained with the Precipitation Processing System. Since one of the features of Hydro-NEXRAD is repeatability of the results, the system promotes systematic studies of new algorithms, comparisons with rain gauge data and error modeling, and uncertainty propagation in hydrologic applications. The system can be considered as prototype of large-scale data dissemination system broadly customized for a specific application. The system could be evolved into a world-wide database of radar data serving the needs of global remote sensing research community.

  1. Architectures for Rainfall Property Estimation From Polarimetric Radar

    NASA Astrophysics Data System (ADS)

    Collis, S. M.; Giangrande, S. E.; Helmus, J.; Troemel, S.

    2014-12-01

    Radars that transmit and receive signals in polarizations aligned both horizontal and vertical to the horizon collect a number of measurements. The relation both between these measurements and between measurements and desired microphysical quantities (such as rainfall rate) is complicated due to a number of scattering mechanisms. The result is that there ends up being an intractable number of often incompatible techniques for extracting geophysical insight. This presentation will discuss methods developed by the Atmospheric Measurement Climate (ARM) Research Facility to streamline the creation of application chains for retrieving rainfall properties for the purposes of fine scale model evaluation. By using a Common Data Model (CDM) approach and working in the popular open source Python scientific environment analysis techniques such as Linear Programming (LP) can be bought to bear on the task of retrieving insight from radar signals. This presentation will outline how we have used these techniques to detangle polarimetric phase signals, estimate a three-dimensional precipitation field and then objectively compare to cloud resolving model derived rainfall fields from the NASA/DoE Mid-Latitude Continental Convective Clouds Experiment (MC3E). All techniques show will be available, open source, in the Python-ARM Radar Toolkit (Py-ART).

  2. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2006-09-30

    Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT) Dr. Qin Xu, CIMMS , University of Oklahoma, 120 David...scientists at CIMMS , the University of Oklahoma. Collaborations between this project and the development of the NWRT phased array radar is coordinated by

  3. High-resolution Rainfall Mapping in Dallas-Fort Worth (DFW) Urban Network of Radars at Multiple Frequencies

    NASA Astrophysics Data System (ADS)

    Chandra, Chandrasekar V.; Chen*, Haonan

    2015-04-01

    Urban flash flood is one of the most commonly encountered hazardous weather phenomena. Unfortunately, the rapid urbanization has made the densely populated areas even more vulnerable to flood risks. Hence, accurate and timely monitoring of rainfall at high spatiotemporal resolution is critical to severe weather warning and civil defense, especially in urban areas. However, it is still challenging to produce high-resolution products based on the large S-band National Weather Service (NWS) Next-Generation Weather Radar (NEXRAD), due to the sampling limitations and Earth curvature effect. Since 2012, the U.S. National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has initiated the development of Dallas-Fort Worth (DFW) radar remote sensing network for urban weather hazards mitigation. The DFW urban radar network consists of a combination of high-resolution X-band radars and a standard NWS NEXRAD radar operating at S-band frequency. High-resolution quantitative precipitation estimation (QPE) is one of the major research goals in the deployment of this urban radar network. It has been shown in the literature that the dual-polarization radar techniques can improve the QPE accuracy over traditional single-polarization radars by rendering more measurements to enhance the data quality, providing more information about rain drop size distribution (DSD), and implying more characteristics of different hydrometeor types. This paper will present the real-time dual-polarization CASA DFW QPE system, which is developed via fusion of observations from both the high-resolution X band radar network and the S-band NWS radar. The specific dual-polarization rainfall algorithms at different frequencies (i.e., S- and X-band) will be described in details. In addition, the fusion methodology combining observations at different temporal resolution will be presented. In order to demonstrate the capability of rainfall

  4. Correlation of S-Band Weather Radar Reflectivity and ACTS Propagation Data in Florida

    NASA Technical Reports Server (NTRS)

    Wolfe, Eric E.; Flikkema, Paul G.; Henning, Rudolf E.

    1997-01-01

    Previous work has shown that Ka-band attenuation due to rainfall and corresponding S-band reflectivity are highly correlated. This paper reports on work whose goal is to determine the feasibility of estimation and, by extension, prediction of one parameter from the other using the Florida ACTS propagation terminal (APT) and the nearby WSR-88D S-band Doppler weather radar facility operated by the National Weather Service. This work is distinguished from previous efforts in this area by (1) the use of a single-polarized radar, preventing estimation of the drop size distribution (e.g., with dual polarization) and (2) the fact that the radar and APT sites are not co-located. Our approach consists of locating the radar volume elements along the satellite slant path and then, from measured reflectivity, estimating the specific attenuation for each associated path segment. The sum of these contributions yields an estimation of the millimeter-wave attenuation on the space-ground link. Seven days of data from both systems are analyzed using this procedure. The results indicate that definite correlation of S-band reflectivity and Ka-band attenuation exists even under the restriciton of this experiment. Based on these results, it appears possible to estimate Ka-band attenuation using widely available operational weather radar data. Conversely, it may be possible to augment current radar reflectivity data and coverage with low-cost attenuation or sky temperature data to improve the estimation of rain rates.

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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 of rain. Hurricane Rita developed on September 18th from a tropical depression and tracked westward into the Gulf of Mexico to reach category 5-strength on September 21st. Rita made landfall at the Texas/Louisiana border on 24th causing as much as 8-9 inches of rain. The current study focuses on analysis of rainfall observations during these two storms using a combination of surface-based and weather radar measurements. The results are based on analyses of small-scale variability of rainfall collected using a dense network of rain gauges in south Louisiana which includes a total of 13 dual rain gauge sites. In addition, an impact-type disdrometer is used to examine the raindrop size spectra characteristics during the two storms. The study will also compare data from the Lake Charles WSR-88D Level II volume scan reflectivity observations to gauge and disdrometer estimates. Implications for the ability of the WSR-88D radar to accurately measure rainfall during these two tropical systems will be investigated and discussed.

  6. Weather radar research at the USA's storm laboratory

    NASA Technical Reports Server (NTRS)

    Doviak, R. J.

    1982-01-01

    Radar research that is directed toward improving storm forecasts and hazard warnings and studying lightning is discussed. The two moderately sensitive Doppler weather radars in central Oklahoma, with their wide dynamic range, have demonstrated the feasibility of mapping wind fields in all weather conditions from the clear skies of quiescent air and disturbed prestorm air near the earth's surface to the optically opaque interior of severe and sometimes tornadic thunderstorms. Observations and analyses of Doppler weather radar data demonstrate that improved warning of severe storm phenomena and improved short-term forecast of storms may be available when Doppler techniques are well integrated into the national network of weather radars. When used in combination with other sensors, it provides an opportunity to learn more about the complex interrelations between the wind, water, and electricity in storms.

  7. High resolution X-Band radar rainfall estimates for a Mediterranean to hyper-arid transition area

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Lokshin, Anton; Notarpietro, Riccardo; Gabella, Marco; Branca, Marco; Bonfil, David; Morin, Efrat

    2015-04-01

    Weather radars provide rainfall estimates with high spatial and temporal resolutions over wide areas. X-Band weather radars are of relatively low-cost and easy to be handled and maintained, moreover they offer extremely high spatial and temporal resolutions and are therefore object of particular interest. Main drawback of these instruments lies on the quantitative accuracy, that can be significantly affected by atmospheric attenuation. Distributed rainfall information is a key issue when hydrological applications are needed for small space-time scale phenomena such as flash floods and debris flows. Moreover, such detailed measurements represent a great benefit for agricultural management of areas characterized by substantial rainfall variability. Two single polarization, single elevation, non-Doppler X-Band weather radars are operational since Oct-2012 in the northern Negev (Israel). Mean annual precipitation over the area drops dramatically from 500 mm/yr at the Mediterranean coast to less than 50 mm/yr at the hyper-arid region near the Dead Sea in less than a 100 km distance. The dryer region close to the Dead Sea is prone to flash floods that often cause casualties and severe damage while the western Mediterranean region is extensively used for agricultural purposes. Measures from a C-Band weather radar located 40-120 km away and from a sparse raingauge network (density ~1gauge/450km2) are also available. C-Band rainfall estimates are corrected using combined physically-based and empirical adjustment of data. The aim of this study is to assess the quantitative accuracy of X-Band rainfall estimates with respect to the combined use of in situ measurements and C-Band observations. Results from a set of storms occurred during the first years of measurements are discussed paying particular attention to: (i) wet radome attenuation, (ii) range dependent degradation including attenuation along the path and (iii) systematic effects related to the Mediterranean to hyper

  8. Rainfall: From Fractals to Multifractals, From Weather to Climate

    NASA Astrophysics Data System (ADS)

    Tchiguirinskaia, I.; Schertzer, D. J.; Fitton, G. F.; Gires, A.

    2013-12-01

    The Intensity-Duration-Frequency (IDF) curves are a classical example of statistical models relating weather and climate time scales. There are numerous standard IDF models. Whereas these parametric models yield similar values near the centre of the distribution, because they are fitted on low order statistics, the extreme quantiles often differ significantly. Unfortunately, these models are based on hypotheses opposite to the long-range dependencies, non-stationarity and clustering of the extremes displayed by rainfall. Searching for methods that could bridge weather and climate time scales of the IDF curves but incorporating physical principles, there have been numerous applications of scaling theories during the last decade. The majority of available theoretical results concerning the scaling extrapolation of the IDF curves has been obtained either with the help of a ';simple scaling' formalism or the multifractal formalism. While the former oversimplifies a multifractal nature of rainfall, the latter often assumes a strict equivalence between the duration (of a sliding window for moving average) and the scale of data observation (corresponding to disjoint windows). In a general manner, the scaling behavior of IDF curves strongly depends on how the durations are defined. An additional complexity arises from the fact that zero-rainfall generally introduces a scaling break between small and large time scales of the rainfall process. In this presentation we discuss the real scaling nature of the rainfall, the nonlinear transformations associated to scaling and duration changing, including for the climate-relevant return periods that very often exceed the length of available historical records. For this purpose, we use a procedure recently developed for near-wall atmospheric turbulence to define conservative flux proxies from empirical data such that they correspond to well-defined stochastic multiplicative processes in the framework of a nonlinear generalized scale

  9. Phase noise effects on turbulent weather radar spectrum parameter estimation

    NASA Technical Reports Server (NTRS)

    Lee, Jonggil; Baxa, Ernest G., Jr.

    1990-01-01

    Accurate weather spectrum moment estimation is important in the use of weather radar for hazardous windshear detection. The effect of the stable local oscillator (STALO) instability (jitter) on the spectrum moment estimation algorithm is investigated. Uncertainty in the stable local oscillator will affect both the transmitted signal and the received signal since the STALO provides transmitted and reference carriers. The proposed approach models STALO phase jitter as it affects the complex autocorrelation of the radar return. The results can therefore by interpreted in terms of any source of system phase jitter for which the model is appropriate and, in particular, may be considered as a cumulative effect of all radar system sources.

  10. Monitoring Changes of Tropical Extreme Rainfall Events Using Differential Absorption Barometric Radar (DiBAR)

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Harrah, Steven; Lawrence, R. Wes; Hu, Yongxiang; Min, Qilong

    2015-01-01

    This work studies the potential of monitoring changes in tropical extreme rainfall events such as tropical storms from space using a Differential-absorption BArometric Radar (DiBAR) operating at 50-55 gigahertz O2 absorption band to remotely measure sea surface air pressure. Air pressure is among the most important variables that affect atmospheric dynamics, and currently can only be measured by limited in-situ observations over oceans. Analyses show that with the proposed radar the errors in instantaneous (averaged) pressure estimates can be as low as approximately 5 millibars (approximately 1 millibar) under all weather conditions. With these sea level pressure measurements, the forecasts, analyses and understanding of these extreme events in both short and long time scales can be improved. Severe weathers, especially hurricanes, are listed as one of core areas that need improved observations and predictions in WCRP (World Climate Research Program) and NASA Decadal Survey (DS) and have major impacts on public safety and national security through disaster mitigation. Since the development of the DiBAR concept about a decade ago, our team has made substantial progress in advancing the concept. Our feasibility assessment clearly shows the potential of sea surface barometry using existing radar technologies. We have developed a DiBAR system design, fabricated a Prototype-DiBAR (P-DiBAR) for proof-of-concept, conducted lab, ground and airborne P-DiBAR tests. The flight test results are consistent with our instrumentation goals. Observational system simulation experiments for space DiBAR performance show substantial improvements in tropical storm predictions, not only for the hurricane track and position but also for the hurricane intensity. DiBAR measurements will lead us to an unprecedented level of the prediction and knowledge on tropical extreme rainfall weather and climate conditions.

  11. Radar based rainfall forecast for sewage systems control.

    PubMed

    Aspegren, H; Bailly, C; Mpé, A; Bazzurro, N; Morgavi, A; Prem, E; Jensen, N E

    2001-01-01

    There has been an increasing demand for accurate rainfall forecast in urban areas from the water industry. Current forecasting systems provided mainly by meteorological offices are based on large-scale prediction and are not well suited for this application. In order to devise a system especially designed for the dynamic management of a sewerage system the "RADAR" project was launched. The idea of this project was to provide a short-term small-scale prediction of rain based on radar images. The prediction methodology combines two methods. An extrapolation method based on a sophisticated cross correlation of images is optimised by a neural network technique. Three different application sites in Europe have been used to validate the system.

  12. Radar volume reflectivity estimation using an array of ground-based rainfall drop size detectors

    NASA Astrophysics Data System (ADS)

    Lane, John; Merceret, Francis; Kasparis, Takis; Roy, D.; Muller, Brad; Jones, W. Linwood

    2000-08-01

    Rainfall drop size distribution (DSD) measurements made by single disdrometers at isolated ground sites have traditionally been used to estimate the transformation between weather radar reflectivity Z and rainfall rate R. Despite the immense disparity in sampling geometries, the resulting Z-R relation obtained by these single point measurements has historically been important in the study of applied radar meteorology. Simultaneous DSD measurements made at several ground sites within a microscale area may be used to improve the estimate of radar reflectivity in the air volume surrounding the disdrometer array. By applying the equations of motion for non-interacting hydrometers, a volume estimate of Z is obtained from the array of ground based disdrometers by first calculating a 3D drop size distribution. The 3D-DSD model assumes that only gravity and terminal velocity due to atmospheric drag within the sampling volume influence hydrometer dynamics. The sampling volume is characterized by wind velocities, which are input parameters to the 3D-DSD model, composed of vertical and horizontal components. Reflectivity data from four consecutive WSR-88D volume scans, acquired during a thunderstorm near Melbourne, FL on June 1, 1997, are compared to data processed using the 3D-DSD model and data form three ground based disdrometers of a microscale array.

  13. The Use of Radar to Improve Rainfall Estimation over the Tennessee and San Joaquin River Valleys

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Gatlin, Patrick N.; Felix, Mariana; Carey, Lawrence D.

    2010-01-01

    This slide presentation provides an overview of the collaborative radar rainfall project between the Tennessee Valley Authority (TVA), the Von Braun Center for Science & Innovation (VCSI), NASA MSFC and UAHuntsville. Two systems were used in this project, Advanced Radar for Meteorological & Operational Research (ARMOR) Rainfall Estimation Processing System (AREPS), a demonstration project of real-time radar rainfall using a research radar and NEXRAD Rainfall Estimation Processing System (NREPS). The objectives, methodology, some results and validation, operational experience and lessons learned are reviewed. The presentation. Another project that is using radar to improve rainfall estimations is in California, specifically the San Joaquin River Valley. This is part of a overall project to develop a integrated tool to assist water management within the San Joaquin River Valley. This involves integrating several components: (1) Radar precipitation estimates, (2) Distributed hydro model, (3) Snowfall measurements and Surface temperature / moisture measurements. NREPS was selected to provide precipitation component.

  14. Mapping wintering waterfowl distributions using weather surveillance radar

    USGS Publications Warehouse

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

    2012-01-01

    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.

  15. Mapping wintering waterfowl distributions using weather surveillance radar.

    PubMed

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

    2012-01-01

    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.

  16. Mapping Wintering Waterfowl Distributions Using Weather Surveillance Radar

    PubMed Central

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

    2012-01-01

    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. PMID:22911816

  17. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2008-09-30

    Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT) Qin Xu CIMMS ...University of Oklahoma, CIMMS ,120 David L. Boren Blvd,Norman,OK,73072 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S...performed by project- supported research scientists at CIMMS , the University of Oklahoma. Collaborations between this project and the development of

  18. Cross-validation Methodology between Ground and GPM Satellite-based Radar Rainfall Product over Dallas-Fort Worth (DFW) Metroplex

    NASA Astrophysics Data System (ADS)

    Chen, H.; Chandrasekar, V.; Biswas, S.

    2015-12-01

    Over the past two decades, a large number of rainfall products have been developed based on satellite, radar, and/or rain gauge observations. However, to produce optimal rainfall estimation for a given region is still challenging due to the space time variability of rainfall at many scales and the spatial and temporal sampling difference of different rainfall instruments. In order to produce high-resolution rainfall products for urban flash flood applications and improve the weather sensing capability in urban environment, the center for Collaborative Adaptive Sensing of the Atmosphere (CASA), in collaboration with National Weather Service (NWS) and North Central Texas Council of Governments (NCTCOG), has developed an urban radar remote sensing network in DFW Metroplex. DFW is the largest inland metropolitan area in the U.S., that experiences a wide range of natural weather hazards such as flash flood and hailstorms. The DFW urban remote sensing network, centered by the deployment of eight dual-polarization X-band radars and a NWS WSR-88DP radar, is expected to provide impacts-based warning and forecasts for benefit of the public safety and economy. High-resolution quantitative precipitation estimation (QPE) is one of the major goals of the development of this urban test bed. In addition to ground radar-based rainfall estimation, satellite-based rainfall products for this area are also of interest for this study. Typical example is the rainfall rate product produced by the Dual-frequency Precipitation Radar (DPR) onboard Global Precipitation Measurement (GPM) Core Observatory satellite. Therefore, cross-comparison between ground and space-based rainfall estimation is critical to building an optimal regional rainfall system, which can take advantages of the sampling differences of different sensors. This paper presents the real-time high-resolution QPE system developed for DFW urban radar network, which is based upon the combination of S-band WSR-88DP and X

  19. Comparison Between Radar and Automatic Weather Station Refractivity Variability

    NASA Astrophysics Data System (ADS)

    Hallali, Ruben; Dalaudier, Francis; Parent du Chatelet, Jacques

    2016-08-01

    Weather radars measure changes in the refractive index of air in the atmospheric boundary layer. The technique uses the phase of signals from ground targets located around the radar to provide information on atmospheric refractivity related to meteorological quantities such as temperature, pressure and humidity. The approach has been successfully implemented during several field campaigns using operational S-band radars in Canada, UK, USA and France. In order to better characterize the origins of errors, a recent study has simulated temporal variations of refractivity based on Automatic Weather Station (AWS) measurements. This reveals a stronger variability of the refractivity during the summer and in the afternoon when the refractivity is the most sensitive to humidity, probably because of turbulence close to the ground. This raises the possibility of retrieving information on the turbulent state of the atmosphere from the variability in radar refractivity. An analysis based on a 1-year dataset from the operational C-band radar at Trappes (near Paris, France) and AWS refractivity variability measurements was used to measure those temporal and spatial variabilities. Particularly during summer, a negative bias increasing with range is observed between radar and AWS estimations, and is well explained by a model based on Taylor's hypotheses. The results demonstrate the possibility of establishing, depending on season, a quantitative and qualitative link between radar and AWS refractivity variability that reflects low-level coherent turbulent structures.

  20. ASSIMILATION OF DOPPLER RADAR DATA INTO NUMERICAL WEATHER MODELS

    SciTech Connect

    Chiswell, S.; Buckley, R.

    2009-01-15

    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

  1. Improved radar data processing algorithms for quantitative rainfall estimation in real time.

    PubMed

    Krämer, S; Verworn, H R

    2009-01-01

    This paper describes a new methodology to process C-band radar data for direct use as rainfall input to hydrologic and hydrodynamic models and in real time control of urban drainage systems. In contrast to the adjustment of radar data with the help of rain gauges, the new approach accounts for the microphysical properties of current rainfall. In a first step radar data are corrected for attenuation. This phenomenon has been identified as the main cause for the general underestimation of radar rainfall. Systematic variation of the attenuation coefficients within predefined bounds allows robust reflectivity profiling. Secondly, event specific R-Z relations are applied to the corrected radar reflectivity data in order to generate quantitative reliable radar rainfall estimates. The results of the methodology are validated by a network of 37 rain gauges located in the Emscher and Lippe river basins. Finally, the relevance of the correction methodology for radar rainfall forecasts is demonstrated. It has become clearly obvious, that the new methodology significantly improves the radar rainfall estimation and rainfall forecasts. The algorithms are applicable in real time.

  2. Doppler weather radar as a meteorite recovery tool

    NASA Astrophysics Data System (ADS)

    Fries, Marc; Fries, Jeffrey

    2010-09-01

    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.

  3. Doppler weather radar with predictive wind shear detection capabilities

    NASA Technical Reports Server (NTRS)

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  4. Improved wet weather wastewater influent modelling at Viikinmäki WWTP by on-line weather radar information.

    PubMed

    Heinonen, M; Jokelainen, M; Fred, T; Koistinen, J; Hohti, H

    2013-01-01

    Municipal wastewater treatment plant (WWTP) influent is typically dependent on diurnal variation of urban production of liquid waste, infiltration of stormwater runoff and groundwater infiltration. During wet weather conditions the infiltration phenomenon typically increases the risk of overflows in the sewer system as well as the risk of having to bypass the WWTP. Combined sewer infrastructure multiplies the role of rainwater runoff in the total influent. Due to climate change, rain intensity and magnitude is tending to rise as well, which can already be observed in the normal operation of WWTPs. Bypass control can be improved if the WWTP is prepared for the increase of influent, especially if there is some storage capacity prior to the treatment plant. One option for this bypass control is utilisation of on-line weather-radar-based forecast data of rainfall as an input for the on-line influent model. This paper reports the Viikinmäki WWTP wet weather influent modelling project results where gridded exceedance probabilities of hourly rainfall accumulations for the next 3 h from the Finnish Meteorological Institute are utilised as on-line input data for the influent model.

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

    PubMed

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

    2013-01-01

    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.

  6. Demonstration of radar reflector detection and ground clutter suppression using airborne weather and mapping radar

    NASA Technical Reports Server (NTRS)

    Anderson, D. J.; Bull, J. S.; Chisholm, J. P.

    1982-01-01

    A navigation system which utilizes minimum ground-based equipment is especially advantageous to helicopters, which can make off-airport landings. Research has been conducted in the use of weather and mapping radar to detect large radar reflectors overland for navigation purposes. As initial studies have not been successful, investigations were conducted regarding a new concept for the detection of ground-based radar reflectors and eliminating ground clutter, using a device called an echo processor (EP). A description is presented of the problems associated with detecting radar reflectors overland, taking into account the EP concept and the results of ground- and flight-test investigations. The echo processor concept was successfully demonstrated in detecting radar reflectors overland in a high-clutter environment. A radar reflector target size of 55 dBsm was found to be adequate for detection in an urban environment.

  7. Coupling Radar Rainfall to Hydrological Models for Water Abstraction Management

    NASA Astrophysics Data System (ADS)

    Asfaw, Alemayehu; Shucksmith, James; Smith, Andrea; MacDonald, Ken

    2015-04-01

    The impacts of climate change and growing water use are likely to put considerable pressure on water resources and the environment. In the UK, a reform to surface water abstraction policy has recently been proposed which aims to increase the efficiency of using available water resources whilst minimising impacts on the aquatic environment. Key aspects to this reform include the consideration of dynamic rather than static abstraction licensing as well as introducing water trading concepts. Dynamic licensing will permit varying levels of abstraction dependent on environmental conditions (i.e. river flow and quality). The practical implementation of an effective dynamic abstraction strategy requires suitable flow forecasting techniques to inform abstraction asset management. Potentially the predicted availability of water resources within a catchment can be coupled to predicted demand and current storage to inform a cost effective water resource management strategy which minimises environmental impacts. The aim of this work is to use a historical analysis of UK case study catchment to compare potential water resource availability using modelled dynamic abstraction scenario informed by a flow forecasting model, against observed abstraction under a conventional abstraction regime. The work also demonstrates the impacts of modelling uncertainties on the accuracy of predicted water availability over range of forecast lead times. The study utilised a conceptual rainfall-runoff model PDM - Probability-Distributed Model developed by Centre for Ecology & Hydrology - set up in the Dove River catchment (UK) using 1km2 resolution radar rainfall as inputs and 15 min resolution gauged flow data for calibration and validation. Data assimilation procedures are implemented to improve flow predictions using observed flow data. Uncertainties in the radar rainfall data used in the model are quantified using artificial statistical error model described by Gaussian distribution and

  8. Exploring single polarization X-band weather radar potentials for local meteorological and hydrological applications

    NASA Astrophysics Data System (ADS)

    Lo Conti, Francesco; Francipane, Antonio; Pumo, Dario; Noto, Leonardo V.

    2015-12-01

    The aim of this study is to evaluate the potential use of a low-cost single polarization X-band weather radar, verified by a disdrometer and a dense rain gauge network, installed as a supporting tool for hydrological applications and for monitoring the urban area of Palermo (Italy). Moreover, this study focuses on studying the temporal variability of the Z-R relation for Mediterranean areas. The radar device is provided with an automatic operational ground-clutter filter developed by the producer. Attention has been paid to the development of blending procedures between radar measurements and other auxiliary instruments and to their suitability for both meteorological and hydrological applications. A general scheme enveloping these procedures and achieving the combination of data retrieved from the weather radar, the optical disdrometer, and the rain gauge network distributed within the monitored area has been designed. The first step of the procedure consists in the calibration of the radar equation by comparing the match between the radar raw data and the disdrometer reflectivity. The second step is the calibration of the Z-R relationship based on the retrieval of parameters that optimize the transformation of disdrometer reflectivity into rainfall intensity, starting from the disdrometer rainfall intensity measurements. The Z-R calibration has been applied to the disdrometer measurements retrieved during a 1 year observation period, after a preliminary segmentation into separated rainfall events. This analysis allows for the characterization of the variability of the Z-R relationship from event to event, deriving some considerations about its predictability as well. Results obtained from this analysis provide a geographical specific record, for the Mediterranean area, for the study of the spatial variability of the Z-R relationship. Finally, the set of operational procedures also includes a correction procedure of radar estimates based on rain gauge data. Each

  9. Radar Scan Strategies for the Patrick Air Force Base Weather Surveillance Radar, Model-74C, Replacement

    NASA Technical Reports Server (NTRS)

    Short, David

    2008-01-01

    The 45th Weather Squadron (45 WS) is replacing the Weather Surveillance Radar, Model 74C (WSR-74C) at Patrick Air Force Base (PAFB), with a Doppler, dual polarization radar, the Radtec 43/250. A new scan strategy is needed for the Radtec 43/250, to provide high vertical resolution data over the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) launch pads, while taking advantage of the new radar's advanced capabilities for detecting severe weather phenomena associated with convection within the 45 WS area of responsibility. The Applied Meteorology Unit (AMU) developed several scan strategies customized for the operational needs of the 45 WS. The AMU also developed a plan for evaluating the scan strategies in the period prior to operational acceptance, currently scheduled for November 2008.

  10. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2007-09-30

    Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT) Dr. Qin Xu CIMMS , University of Oklahoma 120 David L...5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of Oklahoma, CIMMS ,120 David L. Boren Blvd...guidelines for the implementations. The data collections and QC algorithm developments are performed by project- supported research scientists at CIMMS , the

  11. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2005-09-30

    Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT) Dr. Qin Xu CIMMS , University of Oklahoma, 100 E. Boyd...supported research scientists at CIMMS , the University of Oklahoma. Collaborations between this project and the development of the NWRT phased array...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) CIMMS , University of Oklahoma,100 E. Boyd (Rm 1110),Norman,OK,73019 8. PERFORMING

  12. A space-time geostatistical framework for ensemble nowcasting using rainfall radar fields and gauge data

    NASA Astrophysics Data System (ADS)

    Caseri, Angelica; Ramos, Maria Helena; Javelle, Pierre; Leblois, Etienne

    2016-04-01

    Floods are responsible for a major part of the total damage caused by natural disasters. Nowcasting systems providing public alerts to flash floods are very important to prevent damages from extreme events and reduce their socio-economic impacts. The major challenge of these systems is to capture high-risk situations in advance, with good accuracy in the intensity, location and timing of future intense precipitation events. Flash flood forecasting has been studied by several authors in different affected areas. The majority of the studies combines rain gauge data with radar imagery advection to improve prediction for the next few hours. Outputs of Numerical Weather Prediction (NWP) models have also been increasingly used to predict ensembles of extreme precipitation events that might trigger flash floods. One of the challenges of the use of NWP for ensemble nowcasting is to successfully generate ensemble forecasts of precipitation in a short time calculation period to enable the production of flood forecasts with sufficient advance to issue flash flood alerts. In this study, we investigate an alternative space-time geostatistical framework to generate multiple scenarios of future rainfall for flash floods nowcasting. The approach is based on conditional simulation and an advection method applied within the Turning Bands Method (TBM). Ensemble forecasts of precipitation fields are generated based on space-time properties given by radar images and precipitation data collected from rain gauges during the development of the rainfall event. The results show that the approach developed can be an interesting alternative to capture precipitation uncertainties in location and intensity and generate ensemble forecasts of rainfall that can be useful to improve alerts for flash floods, especially in small areas.

  13. Application of the Doppler weather radar in real-time quality control of hourly gauge precipitation in eastern China

    NASA Astrophysics Data System (ADS)

    Zhong, Lingzhi; Zhang, Zhiqiang; Chen, Lin; Yang, Jinhong; Zou, Fengling

    2016-05-01

    The current real-time operational quality control method for hourly rain gauge records at meteorological stations of China is primarily based on a comparison with historical extreme records, and the spatial and temporal consistencies of rain records. However, this method might make erroneous judgments for heavy precipitation because of its remarkable inhomogeneous features. In this study, we develop a Radar Supported Operational Real-time Quality Control (RS_ORQC) method to improve hourly gauge precipitation records in eastern China by using Doppler weather radar data and national automatic rain-gauge network in JJA (i.e., June, July and August) between 2010 and 2011. According to the probability density function (PDF) and cumulative probability density function (CDF), we establish the statistic relationships between NSN precipitation records under 7 radar coverage and radar quantitative precipitation estimation (QPE). The other NSN records under 5 radar coverage are used for the verification. The results show that the correct rate of this radar-supported new method in judging gauge precipitation is close to 99.95% when the hourly rainfall rate is below 10 mm h- 1 and is 96.21% when the rainfall intensity is above 10 mm h- 1. Moreover, the improved quality control method is also applied to evaluate the quality of provincial station network (PSN) precipitation records over eastern China. The correct rate of PSN precipitation records is 99.92% when the hourly rainfall rate is below 10 mm h- 1, and it is 93.33% when the hourly rainfall rate is above 10 mm h- 1. Case studies also exhibit that the radar-supported method can make correct judgments for extreme heavy rainfall.

  14. Investigation of Advanced Radar Techniques for Atmospheric Hazard Detection with Airborne Weather Radar

    NASA Technical Reports Server (NTRS)

    Pazmany, Andrew L.

    2014-01-01

    In 2013 ProSensing Inc. conducted a study to investigate the hazard detection potential of aircraft weather radars with new measurement capabilities, such as multi-frequency, polarimetric and radiometric modes. Various radar designs and features were evaluated for sensitivity, measurement range and for detecting and quantifying atmospheric hazards in wide range of weather conditions. Projected size, weight, power consumption and cost of the various designs were also considered. Various cloud and precipitation conditions were modeled and used to conduct an analytic evaluation of the design options. This report provides an overview of the study and summarizes the conclusions and recommendations.

  15. Beam Propagator for Weather Radars, Modules 1 and 2

    SciTech Connect

    Ortega, Edwin Campos

    2013-10-08

    This program simulates the beam propagation of weather radar pulses under particular and realistic atmospheric conditions (without using the assumption of standard refraction conditions). It consists of two modules: radiosondings_refract_index_many.pro (MAIN MODULE) beam_propagation_function.pro(EXTERNAL FUNCTION) FOR THE MAIN MODULE, THE CODE DOES OUTPUT--INTO A FILE--THE BEAM HEIGHT AS A FUNCTION OF RANGE. THE RADIOSONDE INPUT FILES SHOULD BE ALREADY AVAILABLE BY THE USER. FOR EXAMPLE, RADIOSONDE OBSERVATION FILES CAN BE OBTAINED AT: RADIOSONDE OBSERVATIONS DOWNLOADED AT "http://weather.uwyo.edu/upperair/soounding.html" OR "http://jervis.pyr.ec.gc.ca" THE EXTERNAL FUNCTION DOES THE ACTUAL COMPUTATION OF BEAM PROPAGATION. IT INCLUDES CONDITIONS OF ANOMALOUS PROPAGATION AND NEGATIVE ELEVATION ANGLES. THE EQUATIONS USED HERE WERE DERIVED BY EDWIN CAMPOS, BASED ON THE SNELL-DESCARTES LAW OF REFRACTION, CONSIDERING THE EARTH CURVATURE. THE PROGRAM REQUIRES A COMPILER FOR THE INTERACTIVE DATA LANGUAGE (IDL). DESCRIPTION AND VALIDATION DETAILS HAVE BEEN PUBLISHED IN THE PEER-REVIEWED SCIENTIFIC LITERATURE, AS FOLLOWS: Campos E. 2012. Estimating weather radar coverage over complex terrain, pp.26-32, peer reviewed, in Weather Radar and Hydrology, edited by Moore RJ, Cole SJ and Illingworth AJ. International Association of Hydrological Sciences (IAHS) Press, IAHS Publ. 351. ISBN 978-1-907161-26-1.

  16. Identification and uncertainty estimation of vertical reflectivity profiles using a Lagrangian approach to support quantitative precipitation measurements by weather radar

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    This paper presents a novel approach to estimate the vertical profile of reflectivity (VPR) from volumetric weather radar data using both a traditional Eulerian as well as a newly proposed Lagrangian implementation. For this latter implementation, the recently developed Rotational Carpenter Square Cluster Algorithm (RoCaSCA) is used to delineate precipitation regions at different reflectivity levels. A piecewise linear VPR is estimated for either stratiform or neither stratiform/convective precipitation. As a second aspect of this paper, a novel approach is presented which is able to account for the impact of VPR uncertainty on the estimated radar rainfall variability. Results show that implementation of the VPR identification and correction procedure has a positive impact on quantitative precipitation estimates from radar. Unfortunately, visibility problems severely limit the impact of the Lagrangian implementation beyond distances of 100 km. However, by combining this procedure with the global Eulerian VPR estimation procedure for a given rainfall type (stratiform and neither stratiform/convective), the quality of the quantitative precipitation estimates increases up to a distance of 150 km. Analyses of the impact of VPR uncertainty shows that this aspect accounts for a large fraction of the differences between weather radar rainfall estimates and rain gauge measurements.

  17. Multiparameter radar study of rainfall: Potential application to area-time integral studies

    NASA Technical Reports Server (NTRS)

    Raghavan, R.; Chandrasekar, V.

    1994-01-01

    Multiparameter radars measure one or more additional parameters in addition to the coventional reflectivity factor. The combination of radar observations from a multiparameter radar is used to study the time evolution of rainstorms. A technique is presented to self-consistently compare the area-time integral (ATI) and rainfall volume estimates from convective storms, using two different measurements from a multiparameter radar. Rainfall volumes for the lifetime of individual storms are computed using the reflectivity at S band (10-cm wavelength) as well as one-way specific attenuation at X band (3-cm wavelength). Area-time integrals are computed by summing all areas in each radar snapshot having reflectivities (S band) in excess of a preselected threshold. The multiparameter radar data used in this study were acquired by the National Center for Atmospheric Research (NCAR) CP-2 radar during the Cooperative Huntsville Meteorological Experiment (COHMEX) and the Convection and Precipitation/Electrification Experiment (CaPE), respectively. ATI studies were accomplished in this work using multiparameter radar data acquired during the lifetime of six convective events that occurred in the COHMEX radar coverage area. A case study from the COMHEX field campaign (20 July 1986) was selected to depict the various stages in the evolution of a storm over which the ATI and rainfall volume computations were performed using multiparameter radar data. Another case study from the CaPE field campaign (12 August 1991) was used to demonstrate the evolution of a convective cell based on differential reflectivity observations.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    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.

  19. Predictability of heavy sub-hourly precipitation amounts for a weather radar based nowcasting system

    NASA Astrophysics Data System (ADS)

    Bech, Joan; Berenguer, Marc

    2015-04-01

    Heavy precipitation events and subsequent flash floods are one of the most dramatic hazards in many regions such as the Mediterranean basin as recently stressed in the HyMeX (HYdrological cycle in the Mediterranean EXperiment) international programme. The focus of this study is to assess the quality of very short range (below 3 hour lead times) precipitation forecasts based on weather radar nowcasting system. Specific nowcasting amounts of 10 and 30 minutes generated with a nowcasting technique (Berenguer et al 2005, 2011) are compared against raingauge observations and also weather radar precipitation estimates observed over Catalonia (NE Spain) using data from the Meteorological Service of Catalonia and the Water Catalan Agency. Results allow to discuss the feasibility of issuing warnings for different precipitation amounts and lead times for a number of case studies, including very intense convective events with 30minute precipitation amounts exceeding 40 mm (Bech et al 2005, 2011). As indicated by a number of verification scores single based radar precipitation nowcasts decrease their skill quickly with increasing lead times and rainfall thresholds. This work has been done in the framework of the Hymex research programme and has been partly funded by the ProFEWS project (CGL2010-15892). References Bech J, N Pineda, T Rigo, M Aran, J Amaro, M Gayà, J Arús, J Montanyà, O van der Velde, 2011: A Mediterranean nocturnal heavy rainfall and tornadic event. Part I: Overview, damage survey and radar analysis. Atmospheric Research 100:621-637 http://dx.doi.org/10.1016/j.atmosres.2010.12.024 Bech J, R Pascual, T Rigo, N Pineda, JM López, J Arús, and M Gayà, 2007: An observational study of the 7 September 2005 Barcelona tornado outbreak. Natural Hazards and Earth System Science 7:129-139 http://dx.doi.org/10.5194/nhess-7-129-2007 Berenguer M, C Corral, R Sa0nchez-Diezma, D Sempere-Torres, 2005: Hydrological validation of a radar based nowcasting technique. Journal of

  20. Improving the early-warning of a mud-debris flow using radar rainfall data

    NASA Astrophysics Data System (ADS)

    Jun, Hwandon; Kim, Soojun; Lee, Jiho

    2016-04-01

    The timely and accurate warning of mud-debris flows including landslide hazards is very important to protect life and property. The rainfall estimation uncertainty makes it difficult to issue accurate warning. Traditionally rain gauges have been the main source of surface rainfall measurements. The rain gauges provide an accurate point rainfall estimates, but their spatial resolution is limited by the low-density of a gauge network. The errors associated with interpolation schemes to fill in the missing data over the ungauged sites can introduce significant error due to the long distance between the rain gauge stations and the hazard site (ungauged sites), particularly over rough terrain. The radar system can provide rainfall information at higher temporal and spatial resolutions than was previously possible from rain gauge measurements. While radar provides accurate spatial and temporal resolution of the rainfall field at significant heights above the surface of the earth, numerous measurement errors can result in an inaccurate rainfall depth at the ground. This study attempts to improve mud-debris flow early-warnings through accurate rainfall depth estimation by applying an innovative artificial neural network method. The first scenario uses the nearest rainfall observing site from an ungauged hazard site. The second uses the radar rainfall data and improves the rainfall estimation compared to the first scenario. The third scenario integrates the above two scenarios using both radar and observed rainfall at the sites around the ungauged hazard site, and improves the rainfall estimation by the largest margin. This methodology is applied to the Seoul metropolitan area. The proposed methodology can be applied to improve the confidence in the early-warning of the mud-debris flow hazard in other areas. Acknowledgment This research was supported by a grant (13SCIPS04) from Smart Civil Infrastructure Research Program funded by Ministry of Land, Infrastructure and

  1. Use of radar rainfall estimates in hydrological models: an assessment of predictive uncertainty

    NASA Astrophysics Data System (ADS)

    Borga, M.

    2003-04-01

    Radar estimates of rainfall are being increasingly applied to flood forecasting applications. Errors are inherent both in the process of estimating rainfall from radar and in the modelling of the rainfall-runoff transformation. This paper addresses the problem of evaluating the impact of the rainfall-runoff model parameter uncertainty on the propagation of radar errors trough the hydrological model. Model parameter uncertainty is explicitly accounted for by use of the GLUE (Generalized Likelihood Uncertainty Estimation; Beven and Binley, 1992). The GLUE procedure is used in this study as a means of hydrological model comparison using different rainfall input, provided by dense rain gage networks and by radar estimates according to various processing scenarios. The uncertainty assessment is carried out here through application of radar-estimated precipitation to a lumped rainfall-runoff model for the Brue catchment, a medium-sized watershed located in Somerset, south-west England. The analysis framework allows to evaluate both the wideness of the uncertainty limits and the percentage of observations included in the limits, with varying the behavioural threshold. This helps to assess the impact of radar rainfall errors on the output of a hydrological model previously conditioned using rainfall data from a dense raingauge network. The evaluation is reported in terms of both structural validity and predictive capability of the resulting model output. Several features are worth summarising here. Runoff simulations appear very sensitive to the impact of errors related to variability of reflectivity with height, which dominate the radar error structure. The runoff model defined by using unadjusted radar estimates for higher beam elevations is structurally invalid due to poorly defined input data. Results show the critical importance of proper adjustment of radar estimates. Uncertainty affecting runoff predictions from adjusted radar data are close to those generated by

  2. Development of High Altitude UAV Weather Radars for Hurricane Research

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald; Li, Li-Hua

    2005-01-01

    A proposed effort within NASA called (ASHE) over the past few years was aimed at studying the genesis of tropical disturbances off the east coast of Africa. This effort was focused on using an instrumented Global Hawk UAV with high altitude (%Ok ft) and long duration (30 h) capability. While the Global Hawk availability remains uncertain, development of two relevant instruments, a Doppler radar (URAD - UAV Radar) and a backscatter lidar (CPL-UAV - Cloud Physics Lidar), are in progress. The radar to be discussed here is based on two previous high-altitude, autonomously operating radars on the NASA ER-2 aircraft, the ER-2 Doppler Radar (EDOP) at X-band (9.6 GHz), and the Cloud Radar System (CRS) at W- band (94 GHz). The nadir-pointing EDOP and CRS radars profile vertical reflectivity structure and vertical Doppler winds in precipitation and clouds, respectively. EDOP has flown in all of the CAMEX flight series to study hurricanes over storms such as Hurricanes Bonnie, Humberto, Georges, Erin, and TS Chantal. These radars were developed at Goddard over the last decade and have been used for satellite algorithm development and validation (TRMM and Cloudsat), and for hurricane and convective storm research. We describe here the development of URAD that will measure wind and reflectivity in hurricanes and other weather systems from a top down, high-altitude view. URAD for the Global Hawk consists of two subsystems both of which are at X-band (9.3-9.6 GHz) and Doppler: a nadir fixed-beam Doppler radar for vertical motion and precipitation measurement, and a Conical scanning radar for horizontal winds in cloud and at the surface, and precipitation structure. These radars are being designed with size, weight, and power consumption suitable for the Global Hawk and other UAV's. The nadir radar uses a magnetron transmitter and the scanning radar uses a TWT transmitter. With conical scanning of the radar at a 35" incidence angle over an ocean surface in the absence of

  3. A 10 cm dual frequency Doppler weather radar. Part 1: The radar system

    NASA Astrophysics Data System (ADS)

    Bishop, A. W.; Armstrong, G. M.

    1982-10-01

    Design concepts and test results are summarized for a Doppler weather radar system suitable for precipitation measurements over a wide span of radial velocities and slant ranges, even in the presence of ground clutter. The radar transmits two uniform pulse trains at 2.710 and 2.760 GHz. Uniformly spaced pulses permit ground clutter cancellation of up to 50 dB to be achieved with a three-pole elliptic filter. Pulse spacing at one frequency is consistent with long-range coverage in reflectivity, while spacing of the second is consistent with a wide unambiguous velocity measurement span.

  4. Image processing for hazard recognition in on-board weather radar

    NASA Technical Reports Server (NTRS)

    Kelly, Wallace E. (Inventor); Rand, Timothy W. (Inventor); Uckun, Serdar (Inventor); Ruokangas, Corinne C. (Inventor)

    2003-01-01

    A method of providing weather radar images to a user includes obtaining radar image data corresponding to a weather radar image to be displayed. The radar image data is image processed to identify a feature of the weather radar image which is potentially indicative of a hazardous weather condition. The weather radar image is displayed to the user along with a notification of the existence of the feature which is potentially indicative of the hazardous weather condition. Notification can take the form of textual information regarding the feature, including feature type and proximity information. Notification can also take the form of visually highlighting the feature, for example by forming a visual border around the feature. Other forms of notification can also be used.

  5. Assimilation of Doppler Weather Radar Data in WRF Model for Simulation of Tropical Cyclone Aila

    NASA Astrophysics Data System (ADS)

    Srivastava, Kuldeep; Bhardwaj, Rashmi

    2014-08-01

    For the accurate and effective forecasting of a cyclone, it is critical to have accurate initial structure of the cyclone in numerical models. In this study, Kolkata Doppler weather radar (DWR) data were assimilated for the numerical simulation of a land-falling Tropical Cyclone Aila (2009) in the Bay of Bengal. To study the impact of radar data on very short-range forecasting of a cyclone's path, intensity and precipitation, both reflectivity and radial velocity were assimilated into the weather research and forecasting (WRF) model through the ARPS data assimilation system (ADAS) and cloud analysis procedure. Numerical experiment results indicated that radar data assimilation significantly improved the simulated structure of Cyclone Aila. Strong influences on hydrometeor structures of the initial vortex and precipitation pattern were observed when radar reflectivity data was assimilated, but a relatively small impact was observed on the wind fields at all height levels. The assimilation of radar wind data significantly improved the prediction of divergence/convergence conditions over the cyclone's inner-core area, as well as its wind field in the low-to-middle troposphere (600-900 hPa), but relatively less impact was observed on analyzed moisture field. Maximum surface wind speed produced from DWR-Vr and DWR-ZVr data assimilation experiments were very close to real-time values. The impact of radar data, after final analysis, on minimum sea level pressure was relatively less because the ADAS system does not adjust for pressure due to the lack of pressure observations, and from not using a 3DVAR balance condition that includes pressure. The greatest impact of radar data on forecasting was realized when both reflectivity and wind data (DWR-ZVr and DWR-ZVr00 experiment) were assimilated. It is concluded that after final analysis, the center of the cyclone was relocated very close to the observed position, and simulated cyclone maintained its intensity for a longer

  6. A space-time multifractal analysis on radar rainfall sequences from central Poland

    NASA Astrophysics Data System (ADS)

    Licznar, Paweł; Deidda, Roberto

    2014-05-01

    Rainfall downscaling belongs to most important tasks of modern hydrology. Especially from the perspective of urban hydrology there is real need for development of practical tools for possible rainfall scenarios generation. Rainfall scenarios of fine temporal scale reaching single minutes are indispensable as inputs for hydrological models. Assumption of probabilistic philosophy of drainage systems design and functioning leads to widespread application of hydrodynamic models in engineering practice. However models like these covering large areas could not be supplied with only uncorrelated point-rainfall time series. They should be rather supplied with space time rainfall scenarios displaying statistical properties of local natural rainfall fields. Implementation of a Space-Time Rainfall (STRAIN) model for hydrometeorological applications in Polish conditions, such as rainfall downscaling from the large scales of meteorological models to the scale of interest for rainfall-runoff processes is the long-distance aim of our research. As an introduction part of our study we verify the veracity of the following STRAIN model assumptions: rainfall fields are isotropic and statistically homogeneous in space; self-similarity holds (so that, after having rescaled the time by the advection velocity, rainfall is a fully homogeneous and isotropic process in the space-time domain); statistical properties of rainfall are characterized by an "a priori" known multifractal behavior. We conduct a space-time multifractal analysis on radar rainfall sequences selected from the Polish national radar system POLRAD. Radar rainfall sequences covering the area of 256 km x 256 km of original 2 km x 2 km spatial resolution and 15 minutes temporal resolution are used as study material. Attention is mainly focused on most severe summer convective rainfalls. It is shown that space-time rainfall can be considered with a good approximation to be a self-similar multifractal process. Multifractal

  7. Clutter Rejection for Doppler Weather Radars with Multirate Sampling Schemes

    DTIC Science & Technology

    1990-12-11

    L > 0 02 0 j z uj>cq r LL) M:5ul -j CD <> . t<> t cc 0 0 uj m I.- CL CL ri) CL LU CL U) u S .) cc cr <m > Ij’ I I m 1-20 0 0 6 04 LU wm 0 wcc cc0...Zrni6, Doppler Radar and Weather Observations, Academic Press, New York, 1984. Evans83a. J.E. Evans, "Ground Clutter Cancellation for the NEXRAD System...Witt87a. A. Witt and S.D. Smith, Development and Testing of the Gust Front Algo- rithm, NOAA Environmental Research Laboratories, National Severe Storms

  8. Attenuation of Weather Radar Signals Due to Wetting of the Radome by Rainwater or Incomplete Filling of the Beam Volume

    NASA Technical Reports Server (NTRS)

    Merceret, Francis J.; Ward, Jennifer G.

    2000-01-01

    A search of scientific literature, both printed and electronic, was undertaken to provide quantitative estimates of attenuation effects of rainfall on weather radar radomes. The emphasis was on C-band (5 cm) and S-Band (10 cm) wavelengths. An empirical model was developed to estimate two-way wet radome losses as a function of frequency and rainfall rate for both standard and hydrophobic radomes. The model fits most of the published data within +/- 1 dB at both target wavelengths for rain rates from less than ten to more than 200 mm/hr. Rainfall attenuation effects remain under 1 dB at both frequencies regardless of radome type for rainfall rates up to 10 mm/hr. S-Band losses with a hydrophobic radome such as that on the WSR-88D remain under 1 dB up to 100 mm/hr. C-Band losses on standard radomes such as that on the Patrick AFB (Air Force Base) WSR-74C can reach as much as 5 dB at 50 mm/hr. In addition, calculations were performed to determine the reduction in effective reflectivity, Z, when a radar target is smaller than the sampling volume of the radar. Results are presented for both the Patrick Air Force Base WSR-74C and the WSR-88D as a function of target size and range.

  9. Prediction of a Flash Flood in Complex Terrain. Part I: A Comparison of Rainfall Estimates from Radar, and Very Short Range Rainfall Simulations from a Dynamic Model and an Automated Algorithmic System.

    NASA Astrophysics Data System (ADS)

    Warner, Thomas T.; Brandes, Edward A.; Sun, Juanzhen; Yates, David N.; Mueller, Cynthia K.

    2000-06-01

    Operational prediction of flash floods caused by convective rainfall in mountainous areas requires accurate estimates or predictions of the rainfall distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds generally are small in size, and position errors in the placement of the rainfall can distribute the rain over the wrong watershed. In addition to the need for good rainfall estimates, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the rainfall-rate input data. In part 1 of this study, different techniques for the estimation and prediction of convective rainfall are applied to the Buffalo Creek, Colorado, flash flood of July 1996, during which over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the rainfall was exacerbated by the fact that a considerable fraction of the watershed experienced a wildfire approximately two months prior to the rain event.Precipitation estimates from the National Weather Service Weather Surveillance Radar-1988 Doppler and the National Center for Atmospheric Research S-band, dual-polarization radar, collocated east of Denver, Colorado, were compared. Very short range simulations from a convection-resolving dynamic model that was initialized variationally using the radar reflectivity and Doppler winds were compared with simulations from an automated algorithmic forecast system that also employs the radar data. The radar estimates of rain rate and the two forecasting systems that employ the radar data have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the dynamic model and automated algorithms both produce simulations that could be useful operationally for input to surface-hydrologic models employed for flood warning. Part 2 of this study, reported in a companion paper, describes

  10. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2009-09-30

    Weather Radar Testbed (NWRT) Qin Xu CIMMS , University of Oklahoma 120 David L. Boren Blvd. Norman, OK 73072 phone: (405) 325-3041 fax: (405...AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of Oklahoma, CIMMS ...supported research scientists at CIMMS , the University of Oklahoma. Collaborations between this project and the development of the NWRT PAR is coordinated

  11. Radar Data Quality Control and Assimilation at the National Weather Radar Testbed (NWRT)

    DTIC Science & Technology

    2010-09-30

    National Weather Radar Testbed (NWRT) Qin Xu CIMMS , University of Oklahoma 120 David L. Boren Blvd. Norman, OK 73072 phone: (405) 325-3041 fax... CIMMS ,120 David L. Boren Blvd,Norman,OK,73072 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10...for the implementations. The data collections and QC algorithm developments are performed by project- supported research scientists at CIMMS , the

  12. Improving radar estimates of rainfall using an input subset of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Yang, Tsun-Hua; Feng, Lei; Chang, Lung-Yao

    2016-04-01

    An input subset including average radar reflectivity (Zave) and its standard deviation (SD) is proposed to improve radar estimates of rainfall based on a radial basis function (RBF) neural network. The RBF derives a relationship from a historical input subset, called a training dataset, consisting of radar measurements such as reflectivity (Z) aloft and associated rainfall observation (R) on the ground. The unknown rainfall rate can then be predicted over the derived relationship with known radar measurements. The selection of the input subset has a significant impact on the prediction performance. This study simplified the selection of input subsets and studied its improvement in rainfall estimation. The proposed subset includes: (1) the Zave of the observed Z within a given distance from the ground observation to represent the intensity of a storm system and (2) the SD of the observed Z to describe the spatial variability. Using three historical rainfall events in 1999 near Darwin, Australia, the performance evaluation is conducted using three approaches: an empirical Z-R relation, RBF with Z, and RBF with Zave and SD. The results showed that the RBF with both Zave and SD achieved better rainfall estimations than the RBF using only Z. Two performance measures were used: (1) the Pearson correlation coefficient improved from 0.15 to 0.58 and (2) the average root-mean-square error decreased from 14.14 mm to 11.43 mm. The proposed model and findings can be used for further applications involving the use of neural networks for radar estimates of rainfall.

  13. Rainfall frequency analysis using a hourly rainfall model calibrated on weather patterns: application on Reunion Island

    NASA Astrophysics Data System (ADS)

    Aubert, Yoann; Arnaud, Patrick; Fine, Jean-alain; Cantet, Philippe

    2014-05-01

    The National Research Institute of Science and Technology for Environment and Agriculture (Irstea) has developed an original method for regional rainfall frequency analysis applied on the whole French territory: the SHYREG1 method. It is based on a stochastic hourly rainfall generator. The parameters of the rainfall generator were regionalized at the spatial resolution of 1 km2 thus allowing for the implementation of the model for every 1 km2. Frequency distributions were then derived from long simulated rainfall series for each pixel. Therefore statistical rainfall estimates of various durations (from 1h to 72h) and return periods (from 2 to 1000 years) are made available in a rainfall risk database (intensity-duration-frequency) for the entire French territory. This article presents the application of the SHYREG method in Reunion Island. Reunion Island (with a 2500-km2 surface area) is located in the south-west Indian Ocean. The climate is tropical and characterised by cyclonic rainfall. Tropical cyclones generate heavy rains: during the last one (Bejinsa) in January 2014, rainfall observed exceeded 1000 mm in Cilaos station. Likewise, world records of rainfall, lasting between 5 days (4301 mm in Commerson) and 15 days (6433 mm in Commerson), were observed in Reunion Island during the Hyacinthe Cyclone in January 19802. In mainland France, the calibration of the hourly rainfall generator depends on two seasons (winter from December to May and summer from June to November). However, in order to account for different types of events during a same season, a specific calibration of the hourly rainfall model was necessary. Four types of rainfall event were defined by Météo-France: cyclones, storms, hard rain and rain. Météo-France rainfall data, evenly located over the Island (52 hourly rain gauge stations and 98 daily rain gauge stations), were used to calibrate the hourly rainfall generator. The SHYREG parameters were regionalized based on 17 physiographic maps

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

    PubMed

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

    2011-01-06

    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.

  15. Weather radar observations of the Hekla 2000 eruption cloud, Iceland

    NASA Astrophysics Data System (ADS)

    Lacasse, C.; Karlsdóttir, S.; Larsen, G.; Soosalu, H.; Rose, W. I.; Ernst, G. G. J.

    The Hekla eruption cloud on 26-27 February 2000 was the first volcanic cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire volcanic cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of 30 to 50 m s-1, before it reached an altitude of 11-12 km. The evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30-45 dBz portions of the reflected cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part

  16. National Weather Service

    MedlinePlus

    ... SAFETY Floods Tsunami Beach Hazards Wildfire Cold Tornadoes Air Quality Fog Heat Hurricanes Lightning Safe Boating Rip Currents ... ACTIVE ALERTS FORECAST MAPS RADAR RIVERS, LAKES, RAINFALL AIR QUALITY SATELLITE PAST WEATHER " ); }); American Samoa Guam Puerto Rico/ ...

  17. Advanced Precipitation Radar Antenna to Measure Rainfall From Space

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Yahya; Lin, John; Huang, John; Im, Eastwood; Lou, Michael; Lopez, Bernardo; Durden, Stephen

    2008-01-01

    To support NASA s planned 20-year mission to provide sustained global precipitation measurement (EOS-9 Global Precipitation Measurement (GPM)), a deployable antenna has been explored with an inflatable thin-membrane structure. This design uses a 5.3 5.3-m inflatable parabolic reflector with the electronically scanned, dual-frequency phased array feeds to provide improved rainfall measurements at 2.0-km horizontal resolution over a cross-track scan range of up to 37 , necessary for resolving intense, isolated storm cells and for reducing the beam-filling and spatial sampling errors. The two matched radar beams at the two frequencies (Ku and Ka bands) will allow unambiguous retrieval of the parameters in raindrop size distribution. The antenna is inflatable, using rigidizable booms, deployable chain-link supports with prescribed curvatures, a smooth, thin-membrane reflecting surface, and an offset feed technique to achieve the precision surface tolerance (0.2 mm RMS) for meeting the low-sidelobe requirement. The cylindrical parabolic offset-feed reflector augmented with two linear phased array feeds achieves dual-frequency shared-aperture with wide-angle beam scanning and very low sidelobe level of -30 dB. Very long Ku and Ka band microstrip feed arrays incorporating a combination of parallel and series power divider lines with cosine-over-pedestal distribution also augment the sidelobe level and beam scan. This design reduces antenna mass and launch vehicle stowage volume. The Ku and Ka band feed arrays are needed to achieve the required cross-track beam scanning. To demonstrate the inflatable cylindrical reflector with two linear polarizations (V and H), and two beam directions (0deg and 30deg), each frequency band has four individual microstrip array designs. The Ku-band array has a total of 166x2 elements and the Ka-band has 166x4 elements with both bands having element spacing about 0.65 lambda(sub 0). The cylindrical reflector with offset linear array feeds

  18. wradlib - an Open Source Library for Weather Radar Data Processing

    NASA Astrophysics Data System (ADS)

    Pfaff, Thomas; Heistermann, Maik; Jacobi, Stephan

    2014-05-01

    Even though weather radar holds great promise for the hydrological sciences, offering precipitation estimates with unrivaled spatial and temporal resolution, there are still problems impeding its widespread use, among which are: almost every radar data set comes with a different data format with public reading software being available only rarely. standard products as issued by the meteorological services often do not serve the needs of original research, having either too many or too few corrections applied. Especially when new correction methods are to be developed, researchers are often forced to start from scratch having to implement many corrections in addition to those they are actually interested in. many algorithms published in the literature cannot be recreated using the corresponding article only. Public codes, providing insight into the actual implementation and how an approach deals with possible exceptions are rare. the radial scanning setup of weather radar measurements produces additional challenges, when it comes to visualization or georeferencing of this type of data. Based on these experiences, and in the hope to spare others at least some of these tedious tasks, wradlib offers the results of the author's own efforts and a growing number of community-supplied methods. wradlib is designed as a Python library of functions and classes to assist users in their analysis of weather radar data. It provides solutions for all tasks along a typical processing chain leading from raw reflectivity data to corrected, georeferenced and possibly gauge adjusted quantitative precipitation estimates. There are modules for data input/output, data transformation including Z/R transformation, clutter identification, attenuation correction, dual polarization and differential phase processing, interpolation, georeferencing, compositing, gauge adjustment, verification and visualization. The interpreted nature of the Python programming language makes wradlib an ideal tool

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

    PubMed Central

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

    2011-01-01

    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

  20. The MST radar technique: Requirements for operational weather forecasting

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.

    1983-01-01

    There is a feeling that the accuracy of mesoscale forecasts for spatial scales of less than 1000 km and time scales of less than 12 hours can be improved significantly if resources are applied to the problem in an intensive effort over the next decade. Since the most dangerous and damaging types of weather occur at these scales, there are major advantages to be gained if such a program is successful. The interest in improving short term forecasting is evident. The technology at the present time is sufficiently developed, both in terms of new observing systems and the computing power to handle the observations, to warrant an intensive effort to improve stormscale forecasting. An assessment of the extent to which the so-called MST radar technique fulfills the requirements for an operational mesoscale observing network is reviewed and the extent to which improvements in various types of forecasting could be expected if such a network is put into operation are delineated.

  1. Effects of Multiple Scattering for Millimeter-Wavelength Weather Radars

    NASA Technical Reports Server (NTRS)

    Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood

    2004-01-01

    Effects of multiple scattering on the reflectivity measurement for millimeter-wavelength weather radars are studied, in which backscattering enhancement may play an important role. In the previous works, the backscattering enhancement has been studied for plane wave injection, the reflection of which is received at the infinite distance. In this paper, a finite beam width of a Gaussian antenna pattern along with spherical wave is taken into account. A time-independent second order theory is derived for a single layer of clouds of a uniform density. The ordinary second-order scattering (ladder term) and the second-order backscattering enhancement (cross term) are derived for both the copolarized and cross-polarized waves.

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

    USGS Publications Warehouse

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

    1999-01-01

    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.

  3. Correcting for wind drift in high resolution radar rainfall products: a feasibility study

    NASA Astrophysics Data System (ADS)

    Sandford, Caroline

    2015-12-01

    Increasing demands from emergency responders for accurate flood prediction, particularly in cities, have motivated consistent increases in the resolution of urban drainage models. Such models are now primarily limited by the accuracy and resolution of the initialising rainfall field. Surface rainfall estimates from radar, traditionally derived at scales of order 1 km, are now requested at grid lengths of 100 m to drive improvements in the outputs of these models. Deriving radar precipitation products on grids at the sub-kilometre scale introduces new requirements for the processing of reflectivity measurements into surface rainfall rates. A major source of uncertainty is the physical distance between the radar measurement and the surface onto which precipitation falls. Whilst adjustments to account for inhomogeneity in the vertical reflectivity profile have been extensively investigated, the effects of horizontal displacement have not. This paper discusses the issue of wind drift, first by outlining the need for correction, and then by evaluating the corrections available for impact at the required scale. One correction is detailed and its sensitivity evaluated with respect to the assumptions necessary in its derivation. These sensitivities are verified by trials on the Met Office operational radar processing system, where errors on wind drift displacement estimates are shown to be of order 1 km or more. This is significantly greater than the grid length desired by hydrological users. The paper therefore concludes by suggesting further research necessary to ensure the accuracy of radar precipitation estimates at sub-kilometre resolution.

  4. Spaceborne Doppler Radar Measurements of Rainfall: Correction of Errors Induced by Pointing Uncertainties

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Im, Eastwood; Kobayashi, Satoru; Mascelloni, Roberto; Facheris, Luca

    2005-01-01

    In this paper a sea surface radar echo spectral analysis technique to correct for the rainfall velocity error caused by radar-pointing uncertainty is presented. The correction procedure is quite straightforward when the radar is observing a homogeneous rainfall field. When nonuniform beam filling (NUBF) occurs and attenuating frequencies are used, however, additional steps are necessary in order to correctly estimate the antenna-pointing direction. This new technique relies on the application of the combined frequency-time (CFT) algorithm to correct for uneven attenuation effects on the observed sea surface Doppler spectrum. The performance of this correction technique was evaluated by a Monte Carlo simulation of the Doppler precipitation radar backscatter from high-resolution 3D rain fields (either generated by a cloud resolving numerical model or retrieved from airborne radar measurements). The results show that the antenna-pointing-induced error can, indeed, be reduced by the proposed technique in order to achieve 1 m s(exp -1) accuracy on rainfall vertical velocity estimates.

  5. Comparing two radar rainfall products with the help of Multifractal Analysis

    NASA Astrophysics Data System (ADS)

    Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Bompard, Philippe; Schertzer, Daniel

    2014-05-01

    Distributed rainfall radar data are commonly used in hydrology and increasingly used in urban hydrology. However radar validation and comparison still commonly relies on standard scores such as Nash-Sutcliffe coefficient, Correlation and Quadratic Error, which enable to grasp neither the underlying spatio-temporal structure of the studied rainfall field nor meaningful statistics, i.e. of order larger than two. We implement an innovative methodology that relies on Universal Multifractal (UM) to compare two operational radar products covering the Paris region. The UM framework has been extensively used to characterize and simulate geophysical fields extremely variable over a wide range of scales such as rainfall with the help of only three parameters, which are furthermore physically meaningful. Both Météo-France operational radar mosaic and the CALAMAR radar product use the same single polarization C-band radar data. However their QPE algorithms are different, as well as the calibration with rain gauges. Cartesian fields of final resolution 1 km in space and 5 min in time are used in this study. Three rainfall events that occurred in 2010 and 2011 are used, in order to quantify the quality of the adjustment process we add to this comparison a non-adjusted CALAMAR radar product. As a first step, we compare these radar products to the Val de Marne County network of 27 rain gauges distributed over a 245 Km2 area. Standard scores at various resolutions (5min, 15min, 30min and 1h) are computed. The Météo France radar product is better correlated with these rain gauges data than both CALAMAR products at 5min scale, but we observe the opposite when we increase the time scale. We also observe that the CALAMAR adjustment process improves the correlation with rain gauges. In a second step, both spatial (2D maps) and temporal (1D time series for each pixel) multifractal analyses are performed and the UM parameters computed. Preliminary results suggest that both products do

  6. Airborne laser scan data: a valuable tool with which to infer weather radar partial beam blockage in urban environments

    NASA Astrophysics Data System (ADS)

    Cremonini, Roberto; Moisseev, Dmitri; Chandrasekar, Venkatachalam

    2016-10-01

    High-spatial-resolution weather radar observations are of primary relevance for hydrological applications in urban areas. However, when weather radars are located within metropolitan areas, partial beam blockages and clutter by buildings can seriously affect the observations. Standard simulations with simple beam propagation models and digital elevation models (DEMs) are usually not able to evaluate buildings' contribution to partial beam blockages. In recent years airborne laser scanners (ALSs) have evolved to the state-of-the-art technique for topographic data acquisition. Providing small footprint diameters (10-30 cm), ALS data allow accurate reconstruction of buildings and forest canopy heights. Analyzing the three weather C-band radars located in the metropolitan area of Helsinki, Finland, the present study investigates the benefits of using ALS data for quantitative estimations of partial beam blockages. The results obtained applying beam standard propagation models are compared with stratiform 24 h rainfall accumulation to evaluate the effects of partial beam blockages due to constructions and trees. To provide a physical interpretation of the results, the detailed analysis of beam occultations is achieved by open spatial data sets and open-source geographic information systems.

  7. Potential use of weather radar to study movements of wintering waterfowl

    USGS Publications Warehouse

    Randall, Lori A.; Diehl, Robert H.; Wilson, Barry C.; Barrow, Wylie C.; Jeske, Clinton W.

    2011-01-01

    To protect and restore wintering waterfowl habitat, managers require knowledge of routine wintering waterfowl movements and habitat use. During preliminary screening of Doppler weather radar data we observed biological movements consistent with routine foraging flights of wintering waterfowl known to occur near Lacassine National Wildlife Refuge (NWR), Louisiana. During the winters of 2004–2005 and 2005–2006, we conducted field surveys to identify the source of the radar echoes emanating from Lacassine NWR. We compared field data to weather radar reflectivity data. Spatial and temporal patterns consistent with foraging flight movements appeared in weather radar data on all dates of field surveys. Dabbling ducks were the dominant taxa flying within the radar beam during the foraging flight period. Using linear regression, we found a positive log-linear relationship between average radar reflectivity (Z) and number of birds detected over the study area (P r2 = 0.62, n = 40). Ground observations and the statistically significant relationship between radar data and field data confirm that Doppler weather radar recorded the foraging flights of dabbling ducks. Weather radars may be effective tools for wintering waterfowl management because they provide broad-scale views of both diurnal and nocturnal movements. In addition, an extensive data archive enables the study of wintering waterfowl response to habitat loss, agricultural practices, wetland restoration, and other research questions that require multiple years of data.

  8. Modeling a densely urbanized watershed with an artificial neural network, weather radar and telemetric data

    NASA Astrophysics Data System (ADS)

    Pereira Filho, Augusto José; dos Santos, Cláudia Cristina

    2006-02-01

    Artificial neural networks (ANN) are widely used in a myriad of fields of research and development, including the predictability of time series. This work is concerned with one of such applications to simulate and to forecast stage level and streamflow at the Tamanduateí river watershed, one of the main tributaries of the Alto Tietê river watershed in São Paulo State, Brazil. This heavily urbanized watershed is within the Metropolitan Area of São Paulo (MASP) where recurrent flash floods affect a population of more than 17 million inhabitants. Flash floods events between 1991 and 1995 were selected and divided up into three groups for training, verification and forecasting purposes. Weather radar rainfall estimation and telemetric stage level and streamflow data were input to a three-layer feed forward ANN trained with the Linear Least Square Simplex training algorithm (LLSSIM) by Hsu et al. [Hsu, K.L., Gupta, H.V., Sorooshian, S., 1996. A superior training strategy for three-layer feed forward artificial neural networks. Tucson, University of Arizona. (Technique report, HWR no. 96-030, Department of Hydrology and Water Resources)]. The performance of the ANN is improved by 40% when either streamflow or stage level were input together with the rainfall. The ANN simulated flood waves tend to be dominated by phase errors. The ANN showed slightly better results then a multi-parameter auto-regression model and indicates its usefulness in flash flood forecasting.

  9. Simulation of Tornado over Brahmanbaria on 22 March 2013 using Doppler Weather Radar and WRF Model

    NASA Astrophysics Data System (ADS)

    Das, M. K.; Chowdhury, M.; Das, S.

    2013-12-01

    A tornado accompanied with thunderstorm, rainfall and hailstorm affected Brahmanbaria of Bangladesh in the afternoon of 22 March 2013. The tornadic storms are studied based on field survey, ground and radar observations. Low level moisture influx by southerly flow from the Bay of Bengal coupled with upper level westerly jet stream causing intense instability and shear in the wind fields triggered a series of storms for the day. The exact time and locations of the storms are investigated by using the Agartala and Cox's Bazar Doppler Weather Radar (DWR). Subsequently, the storms are simulated by using the WRF-ARW model at 1 km horizontal resolution based on 6 hourly analyses and boundary conditions of NCEP-FNL. Among the typical characteristics of the storms, the CAPE, surface wind speed, flow patterns, T-Φ gram, rainfall, sea level pressure, vorticity and vertical velocity are studied. Results show that while there are differences of 2-3 hours between the observed and simulated time of the storms, the distances between observed and simulated locations of the storms are several tens of kilometers. The maximum CAPE was generally above 2400 J kg-1 in the case. The maximum intensity of surface wind speed simulated by the model was only 38 m sec-1. This seems to be underestimated. The highest vertical velocity (updraft) simulated by the model was 250 m sec-1 around 800-950 hPa. The updraft reached up to 150 hPa. It seems that the funnel vortex reached the ground, and might have passed some places a few meters above the surface. According to the Fujita Pearson scale, this tornado can be classified as F-2 with estimated wind speed of 50-70 ms-1. Keywords: Tornado, DWR, NCEP-FNL, T-Φ gram, CAPE.

  10. A Comparison of Radar Rainfall Estimates and Rain Gage Measurements during Two Denver Thunderstorms

    DTIC Science & Technology

    1992-01-01

    80 viii CHAPTER I INTRODUCTION Accurate measurements of thunderstorm rainfall are essential for providing timely guidance on flash flood potential...throughout the drainage basins effecting the Denver metropolitan area (see Figure 2.1). This network is used to provide flash flood predictions for...report of flash flooding 40 miles southwest of Denver at 1520 MDT (NOAA, 1991). 2. Severe weather reports Reports of severe weather were numerous in the

  11. Can Compressed Sensing Be Applied To Dual-Polarimetric Weather Radars?

    NASA Astrophysics Data System (ADS)

    Mishra, K.; Kruger, A.; Krajewski, W. F.

    2013-12-01

    The recovery of sparsely-sampled signals has long attracted considerable research interest in various fields such as reflection seismology, microscopy, and astronomy. Recently, such recovery techniques have been formalized as a sampling method called compressed sensing (CS) which uses few linear and non-adaptive measurements to reconstruct a signal that is sparse in a known domain. Many radar and remote sensing applications require efficient and rapid data acquisition. CS techniques have, therefore, enormous potential in dramatically changing the way the radar samples and processes data. A number of recent studies have investigated CS for radar applications with emphasis on point target radars, and synthetic aperture radar (SAR) imaging. CS radar holds the promise of compressing-while-sampling, and may yield simpler receiver hardware which uses low-rate ADCs and eliminates pulse compression/matched filter. The need of fewer measurements also implies that a CS radar may need smaller dwell times without significant loss of information. Finally, CS radar data could be used for improving the quality of low-resolution radar observations. In this study, we explore the feasibility of using CS for dual-polarimetric weather radars. In order to recover a signal in CS framework, two conditions must be satisfied: sparsity and incoherence. The sparsity of weather radar measurements can be modeled in several domains such as time, frequency, joint time-frequency domain, or polarimetric measurement domains. The condition of incoherence relates to the measurement process which, in a radar scenario, would imply designing an incoherent transmit waveform or an equivalent scanning strategy with an existing waveform. In this study, we formulate a sparse signal model for precipitation targets as observed by a polarimetric weather radar. The applicability of CS for such a signal model is then examined through simulations of incoherent measurements along with real weather data obtained

  12. System Concepts for the Advanced Post-TRMM Rainfall Profiling Radars

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Smith, Eric A.

    2000-01-01

    Global rainfall is the primary distributor of latent heat through atmospheric circulation. The recently launched Tropical Rainfall Measuring Mission satellite is dedicated to advance our understanding of tropical precipitation patterns and their implications on global climate and its change. The Precipitation Radar (PR) aboard the satellite is the first radar ever flown in space and has provided. exciting, new data on the 3-D rain structures for a variety of scientific uses. However, due to the limited mission lifetime and the dynamical nature of precipitation, the TRMM PR data acquired cannot address all the issues associated with precipitation, its related processes, and the long-term climate variability. In fact, a number of new post-TRMM mission concepts have emerged in response to the recent NASA's request for new ideas on Earth science missions at the post 2002 era. This paper will discuss the system concepts for two advanced, spaceborne rainfall profiling radars. In the first portion of this paper, we will present a system concept for a second-generation spaceborne precipitation radar for operations at the Low Earth Orbit (LEO). The key PR-2 electronics system will possess the following capabilities: (1) A 13.6/35 GHz dual frequency radar electronics that has Doppler and dual-polarization capabilities. (2) A large but light weight, dual-frequency, wide-swath scanning, deployable antenna. (3) Digital chirp generation and the corresponding on-board pulse compression scheme. This will allow a significant improvement on rain signal detection without using the traditional, high-peak-power transmitters and without sacrificing the range resolution. (4) Radar electronics and algorithm to adaptively scan the antenna so that more time can be spent to observe rain rather than clear air. and (5) Built-in flexibility on the radar parameters and timing control such that the same radar can be used by different future rain missions. This will help to reduce the overall

  13. Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations

    NASA Astrophysics Data System (ADS)

    Bolen, Steven M.; Chandrasekar, V.

    2003-06-01

    The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ≥ 0.5°/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

  14. Spectral analyses of the dual polarization Doppler weather radar data

    NASA Astrophysics Data System (ADS)

    Bachmann, Svetlana Monakhova

    2007-12-01

    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.

  15. Analysis of the heavy rainfall from Typhoon Plum using Doppler Radar

    NASA Astrophysics Data System (ADS)

    Jin, W.; Qu, Y.

    2013-12-01

    Using reanalysis and observational data and Doppler radar data, the structure and characteristics of the synoptic and mesoscale meteorological background are analyzed for a heavy rainfall over Xiaoshipeng town of Yingkou City in Liaoning province, China. The results show that: (1) several synoptic scale patterns formed the background for the heavy rainfall: the Pacific subtropical high extended to the West; a strong tropical storm named "Plum" moved to the northwest after it had landed; Northwest jet transported a lot of the water vapor to Liaoning; the weak cold air of Baikal Lake moved to south along the ridge before the northwest flow impact to Liaoning. (2) the factors conducive to strong convective precipitation: the existence of a deep wet layer, a narrow CAPE zone and a relative weak vertical wind sheer. (3) there is nonstop generation of new mesoscale convective cells during the heavy rainfall. There exists a maximum wind zone of 24m/s in the lower layer and a strong radar echo with 35dBz above 5km. And the variation of the low level southwest jet is in step with the variation of rainfall amount. The cyclonic convergence of the warm wet air in the mid-low level is a factor triggering and strengthening convection. The nonstop generation of mesoscale convective cells and the water vapor transport from the low level southwest jet are pushing the rainfall radar echo to above 40dBz and lasting for more than 5 hours and are considered the direct cause of this heavy rainfall.

  16. Flood frequency analysis using radar rainfall fields and stochastic storm transposition

    NASA Astrophysics Data System (ADS)

    Wright, Daniel B.; Smith, James A.; Baeck, Mary Lynn

    2014-02-01

    Flooding is the product of complex interactions among spatially and temporally varying rainfall, heterogeneous land surface properties, and drainage network structure. Conventional approaches to flood frequency analysis rely on assumptions regarding these interactions across a range of scales. The impacts of these assumptions on flood risk estimates are poorly understood. In this study, we present an alternative flood frequency analysis framework based on stochastic storm transposition (SST). We use SST to synthesize long records of rainfall over the Charlotte, North Carolina, USA metropolitan area by "reshuffling" radar rainfall fields, within a probabilistic framework, from a 10 year (2001-2010) high-resolution (15 min, 1 km2) radar data set. We use these resampled fields to drive a physics-based distributed hydrologic model for a heavily urbanized watershed in Charlotte. The approach makes it possible to estimate discharge return periods for all points along the drainage network without the assumptions regarding rainfall structure and its interactions with watershed features that are required using conventional methods. We develop discharge estimates for return periods from 10 to 1000 years for a range of watershed scales up to 110 km2. SST reveals that flood risk in the larger subwatersheds is dominated by tropical storms, while organized thunderstorm systems dominate flood risk in the smaller subwatersheds. We contrast these analyses with examples of potential problems that can arise from conventional frequency analysis approaches. SST provides an approach for examining the spatial extent of flooding and for incorporating nonstationarities in rainfall or land use into flood risk estimates.

  17. Simulations of Dual-Frequency Radar Rainfall Retrievals

    NASA Astrophysics Data System (ADS)

    D'Adderio, Leo Pio; Tokay, Ali; Meneghini, Robert; Liao, Liang; Petersen, Walter A.; Porcù, Federico

    2016-04-01

    The retrieval of raindrop size distribution (DSD) is one of the key objectives of National Aeronautics and Space Administration (NASA) Global Precipitation Measurement (GPM) Mission. The dual-frequency precipitation radar (DPR) on board GPM core satellite is the primary resource for the retrieval of DSD. The DPR operates at Ku- and Ka-band and these frequencies have different sensitivities to the precipitation at the surface. Both frequencies are subject to the attenuation but at different magnitude. The high sensitivity of Ka-band measurements intends to detect solid and/or light liquid precipitation, while Ku-band frequency will be able to measure relatively higher intensity precipitation. The data from simultaneous Ka- and Ku-band measurements will allow a more accurate estimation of the DSD. The DSD retrieval algorithm uses three-parameter gamma distribution where mass weighted diameter (Dmass), normalized intercept parameter with respect to the liquid water content, and the shape parameter will be derived from dual-frequency radar measurements. A key problem is the retrieval of three unknown with two measurements. The simulation of the dual frequency ratio (DFR), using disdrometric data collected in different field campaigns of Ground Validation (GV) program of GPM mission, can cast light on this retrieval problem. Furthermore, the use of a third and/or different wavelength in the satellite measurements can be an added value to correctly retrieve both light and heavy rain. This study seeks relationship between the DFR and Dmass in different rain regimes. The DFR based both on Ka-/Ku-band and on frequencies other than Ka-/Ku-band is investigated. The dependence on the gamma distribution shape parameter, which is set to three in the DPR DSD retrieval algorithm, of the DFR-Dmass relationship is also analyzed.

  18. Disaggregating radar-derived rainfall measurements in East Azarbaijan, Iran, using a spatial random-cascade model

    NASA Astrophysics Data System (ADS)

    Fouladi Osgouei, Hojjatollah; Zarghami, Mahdi; Ashouri, Hamed

    2016-04-01

    The availability of spatial, high-resolution rainfall data is one of the most essential needs in the study of water resources. These data are extremely valuable in providing flood awareness for dense urban and industrial areas. The first part of this paper applies an optimization-based method to the calibration of radar data based on ground rainfall gauges. Then, the climatological Z-R relationship for the Sahand radar, located in the East Azarbaijan province of Iran, with the help of three adjacent rainfall stations, is obtained. The new climatological Z-R relationship with a power-law form shows acceptable statistical performance, making it suitable for radar-rainfall estimation by the Sahand radar outputs. The second part of the study develops a new heterogeneous random-cascade model for spatially disaggregating the rainfall data resulting from the power-law model. This model is applied to the radar-rainfall image data to disaggregate rainfall data with coverage area of 512 × 512 km2 to a resolution of 32 × 32 km2. Results show that the proposed model has a good ability to disaggregate rainfall data, which may lead to improvement in precipitation forecasting, and ultimately better water-resources management in this arid region, including Urmia Lake.

  19. X-Band local area weather radar--preliminary calibration results.

    PubMed

    Jensen, N E

    2002-01-01

    DHI has developed a cost-effective X-Band Local Area Weather Radar (LAWR) with a typical range (radius) of 60 km, 500 x 500 m areal resolution and 253 reflection levels. The development is performed in a co-operation with a number of European partners, including Danish Meteorological Institute. The specifications of the weather radar and preliminary results from the calibration are presented. Good calibration results have been obtained using high-resolution rain gauges.

  20. On the potential use of radar-derived information in operational numerical weather prediction

    NASA Technical Reports Server (NTRS)

    Mcpherson, R. D.

    1986-01-01

    Estimates of requirements likely to be levied on a new observing system for mesoscale meteonology are given. Potential observing systems for mesoscale numerical weather prediction are discussed. Thermodynamic profiler radiometers, infrared radiometer atmospheric sounders, Doppler radar wind profilers and surveillance radar, and moisture profilers are among the instruments described.

  1. Estimating reflectivity values from wind turbines for analyzing the potential impact on weather radar services

    NASA Astrophysics Data System (ADS)

    Angulo, I.; Grande, O.; Jenn, D.; Guerra, D.; de la Vega, D.

    2015-05-01

    The World Meteorological Organization (WMO) has repeatedly expressed concern over the increasing number of impact cases of wind turbine farms on weather radars. Current signal processing techniques to mitigate wind turbine clutter (WTC) are scarce, so the most practical approach to this issue is the assessment of the potential interference from a wind farm before it is installed. To do so, and in order to obtain a WTC reflectivity model, it is crucial to estimate the radar cross section (RCS) of the wind turbines to be built, which represents the power percentage of the radar signal that is backscattered to the radar receiver. For the proposed model, a representative scenario has been chosen in which both the weather radar and the wind farm are placed on clear areas; i.e., wind turbines are supposed to be illuminated only by the lowest elevation angles of the radar beam. This paper first characterizes the RCS of wind turbines in the weather radar frequency bands by means of computer simulations based on the physical optics theory and then proposes a simplified model to estimate wind turbine RCS values. This model is of great help in the evaluation of the potential impact of a certain wind farm on the weather radar operation.

  2. Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 4 - TRMM rain radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Atlas, David; Awaka, Jun; Okamoto, Ken'ichi; Ihara, Toshio; Nakamura, Kenji; Kozu, Toshiaki; Manabe, Takeshi

    1990-01-01

    The basic system parameters for the Tropical Rainfall Measuring Mission (TRMM) radar system are frequency, beamwidth, scan angle, resolution, number of independent samples, pulse repetition frequency, data rate, and so on. These parameters were chosen to satisfy NASA's mission requirements. Six candidates for the TRMM rain radar were studied. The study considered three major competitive items: (1) a pulse-compression radar vs. a conventional radar; (2) an active-array radar with a solid state power amplifier vs. a passive-array radar with a traveling-wave-tube amplifier; and (3) antenna types (planar-array antenna vs. cylindrical parabolic antenna). Basic system parameters such as radar sensitivities, power consumption, weight, and size of these six types are described. Trade-off studies of these cases show that the non-pulse-compression active-array radar with a planar array is considered to be the most suitable candidate for the TRMM rain radar at 13.8 GHz.

  3. Spectral Analysis of Polarimetric Weather Radar Data With Multiple Processes in a Resolution Volume

    DTIC Science & Technology

    2007-04-01

    single radar resolution volume. An example of clear air observed using an S- band dual polarization radar is presented. Heretofore, migrating birds...WEATHER CONDITIONS Time-series data were collected with the NOAA/NSSL research S- band radar (KOUN) on September 7, 2004 at 11 pm local time (04...densities ( ZDR , hv, and ) along the 180 radial are shown in Fig. 1a, b, c , d. Only spectral coefficients with Sh > 5dB above the noise are displayed. One

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  5. Using rainfall radar data to improve interpolated maps of dose rate in the Netherlands.

    PubMed

    Hiemstra, Paul H; Pebesma, Edzer J; Heuvelink, Gerard B M; Twenhöfel, Chris J W

    2010-12-01

    The radiation monitoring network in the Netherlands is designed to detect and track increased radiation levels, dose rate more specifically, in 10-minute intervals. The network consists of 153 monitoring stations. Washout of radon progeny by rainfall is the most important cause of natural variations in dose rate. The increase in dose rate at a given time is a function of the amount of progeny decaying, which in turn is a balance between deposition of progeny by rainfall and radioactive decay. The increase in progeny is closely related to average rainfall intensity over the last 2.5h. We included decay of progeny by using weighted averaged rainfall intensity, where the weight decreases back in time. The decrease in weight is related to the half-life of radon progeny. In this paper we show for a rainstorm on the 20th of July 2007 that weighted averaged rainfall intensity estimated from rainfall radar images, collected every 5min, performs much better as a predictor of increases in dose rate than using the non-averaged rainfall intensity. In addition, we show through cross-validation that including weighted averaged rainfall intensity in an interpolated map using universal kriging (UK) does not necessarily lead to a more accurate map. This might be attributed to the high density of monitoring stations in comparison to the spatial extent of a typical rain event. Reducing the network density improved the accuracy of the map when universal kriging was used instead of ordinary kriging (no trend). Consequently, in a less dense network the positive influence of including a trend is likely to increase. Furthermore, we suspect that UK better reproduces the sharp boundaries present in rainfall maps, but that the lack of short-distance monitoring station pairs prevents cross-validation from revealing this effect.

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

    PubMed

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

    2013-01-01

    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.

  7. Synoptic Analysis of Heavy Rainfall and Flood Observed in Izmir on 20 May 2015 Using Radar and Satellite Images

    NASA Astrophysics Data System (ADS)

    Avsar, Ercument

    2016-07-01

    In this study, a meteorological analysis is conducted on the sudden and heavy rainfall that occurred in Izmir on May 20, 2015. The barotropic model that is observed in upper carts is shown in detail. We can access the data of and analyze the type, severity and amount of many meteorological parameters using the meteorological radars that form a remote sensing system. The one field that uses the radars most intensively is rainfall. Images from the satellite and radar systems are used in the meteorological analysis of the heavy rainfall that occurred in Izmir on 20 May 2015, and the development of the system that led to this rainfall is shown. In this study, data received from Bornova Automatic Meteorological Observation Station (OMGI), which is under the management of Meteorology General Directorate (MGM), Izmir 2. Regional Directorate; satellite images; Radar PPI (Plan Position Indicator) and Radar MAX (Maximum Display) images are evaluated. In addition, synoptic situation, outputs of numerical estimation models, indices calculated from Skew T Log-P diagram are shown. All these results are mapped and analyzed. At the end of these analyses, it is found that this sudden rainfall had developed according to the frontal system motion. A barotropic model occurred on the day of the rainfall over the Aegean Region. As a result of the rainfall that happened in Izmir at 12.00 UTC (Universal Coordinated Time), the May month rainfall record for the last 64 years is achieved with a rainfall amount of 67.7 mm per meter square. Keywords: Izmir, barotropic model, heavy rainfall, radar, synoptic analysis

  8. Evaluating of the rain effect on tropical rainfall mapping mission precipitation radar backscatter at low incidence angles

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan

    2016-10-01

    This paper evaluates the rain effects on Ku-band radar backscatter at low incidence angles. The data used consisted of the sea surface backscatter and averaged rain rates from Tropical Rainfall Mapping Mission precipitation radar (TRMM PR) measurements and the collocated 10-m height numerical prediction wind speeds from the European Centre for Medium-Range Weather Forecasts (ECMWF). The wind-induced backscatter was estimated by the Ku-band low incidence backscatter model (KuLMOD) and possible bias due to different wind speed inputs was considered. The rain effect was analysed by comparing the TRMM PR-measured surface backscatter for the rain-affected sea surface with the collocated wind-induced backscatter. We found that the surface backscatter decreases with increases in the averaged rain rate. The rain-induced backscatter was clearly dependent of the wind speed and was slightly dependent of the incidence angle. Results show that it is necessary to develop a wind and rain backscatter model instead of single wind backscatter model.

  9. Detection of convective cells with a potential to produce local heavy rainfalls by a C-band polarimetric radar

    NASA Astrophysics Data System (ADS)

    Adachi, Ahoro; Kobayashi, Takahisa; Yamauchi, Hiroshi; Onogi, Shigeru

    2011-11-01

    Recent studies have shown that polarimetric radars are capable of providing distributions of rain intensity with high accuracy. Variables obtained by the polarimetric radars include radar reflectivity factor (Zhh), differential propagation phase (Φdp) and differential reflectivity (Zdr). A number of methods to estimate rain intensity from these variables have been proposed. In this study, the rain intensity estimated from the differential reflectivity and radar reflectivity factor measured with a C-band polarimetric radar is used to analyze a local heavy rainfall event as a case study because the differential reflectivity measured with C-band radar is more sensitive to large raindrops associated with heavy rainfalls than is radars operating at other frequencies. Results show that the estimated rainfall intensity agrees well with surface observations made during the event. Moreover, the so-called high Zdr column, a large differential reflectivity region was clearly analyzed aloft about 10 minutes prior to the local heavy rainfall on the ground, suggesting that the differential reflectivity observed with C-band polarimetric radar can be a good index to detect heavy precipitation events in advance.

  10. The Eyjafjöll explosive volcanic eruption from a microwave weather radar perspective

    NASA Astrophysics Data System (ADS)

    Marzano, F. S.; Lamantea, M.; Montopoli, M.; di Fabio, S.; Picciotti, E.

    2011-09-01

    The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are analyzed and quantitatively interpreted by using ground-based weather radar data and the Volcanic Ash Radar Retrieval (VARR) technique. The Eyjafjöll eruptions have been continuously monitored by the Keflavík C-band weather radar, located at a distance of about 155 km from the volcano vent. Considering that the Eyjafjöll volcano is approximately 20 km from the Atlantic Ocean and that the northerly winds stretched the plume toward the mainland Europe, weather radars are the only means to provide an estimate of the total ejected tephra. The VARR methodology is summarized and applied to available radar time series to estimate the plume maximum height, ash particle category, ash volume, ash fallout and ash concentration every 5 min near the vent. Estimates of the discharge rate of eruption, based on the retrieved ash plume top height, are provided together with an evaluation of the total erupted mass and volume. Deposited ash at ground is also retrieved from radar data by empirically reconstructing the vertical profile of radar reflectivity and estimating the near-surface ash fallout. Radar-based retrieval results cannot be compared with ground measurements, due to the lack of the latter, but further demonstrate the unique contribution of these remote sensing products to the understating and modelling of explosive volcanic ash eruptions.

  11. The Eyjafjöll explosive volcanic eruption from a microwave weather radar perspective

    NASA Astrophysics Data System (ADS)

    Marzano, F. S.; Lamantea, M.; Montopoli, M.; di Fabio, S.; Picciotti, E.

    2011-04-01

    The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are analyzed and quantitatively interpreted by using ground-based weather radar data and volcanic ash radar retrieval (VARR) technique. The Eyjafjöll eruptions have been continuously monitored by the Keflavík C-band weather radar, located at a distance of about 155 km from the volcano vent. Considering that the Eyjafjöll volcano is approximately 20 km far from the Atlantic Ocean and that the northerly winds stretched the plume toward the mainland Europe, weather radars are the only means to provide an estimate of the total ejected tephra. The VARR methodology is summarized and applied to available radar time series to estimate the plume maximum height, ash particle category, ash volume, ash fallout and ash concentration every 5 min near the vent. Estimates of the discharge rate of eruption, based on the retrieved ash plume top height, are provided together with an evaluation of the total erupted mass and volume. Deposited ash at ground is also retrieved from radar data by empirically reconstructing the vertical profile of radar reflectivity and estimating the near-surface ash fallout. Radar-based retrieval results cannot be compared with ground measurements, due to the lack of the latter, but further demonstrate the unique contribution of these remote sensing products to the understating and modelling of explosive volcanic ash eruptions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  13. Heavy rains over Chennai and surrounding areas as captured by Doppler weather radar during Northeast Monsoon 2015: a case study

    NASA Astrophysics Data System (ADS)

    Kamaljit, Ray; Kannan, B. A. M.; Stella, S.; Sen, Bikram; Sharma, Pradip; Thampi, S. B.

    2016-05-01

    During the Northeast monsoon season, India receives about 11% of its annual rainfall. Many districts in South Peninsula receive 30-60% of their annual rainfall. Coastal Tamil Nadu receives 60% of its annual rainfall and interior districts about 40-50 %. During the month of November, 2015, three synoptic scale weather systems affected Tamil Nadu and Pondicherry causing extensive rainfall activity over the region. Extremely heavy rains occurred over districts of Chennai, Thiruvallur and Kancheepuram, due to which these 3 districts were fully inundated. 122 people in Tamil Nadu were reported to have died due to the flooding, while over 70,000 people had been rescued. State government reported flood damage of the order of around Rs 8481 Crores. The rainfall received in Chennai district during 1.11.2015 to 5.12.2015 was 1416.8 mm against the normal of 408.4 mm. The extremely heavy rains were found to be associated with strong wind surges at lower tropospheric levels, which brought in lot of moisture flux over Chennai and adjoining area. The subtropical westerly trough at mid-tropospheric levels extended much southwards than its normal latitude, producing favorable environment for sustained rising motions ahead of approaching trough over coastal Tamil Nadu. Generated strong upward velocities in the clouds lifted the cloud tops to very high levels forming deep convective clouds. These clouds provided very heavy rainfall of the order of 150-200 mm/hour. In this paper we have used radar data to examine and substantiate the cloud burst that led to these torrential rains over Chennai and adjoining areas during the Northeast Monsoon period, 2015.

  14. Rainfall rate measurement with a polarimetric radar at an attenuated wavelength

    NASA Astrophysics Data System (ADS)

    Sauvageot, Henri; Mesnard, Frédéric; Illingworth, Anthony J.; Goddard, John W. F.

    Among the many ways investigated for radar estimation of rainfall, polarimetric methods are the most promising. However most polarimetric algorithms are degraded by attenuation by precipitation and clouds and by calibration error. A new method was recently proposed in which the differential polarimetric attenuation is used to perform an accurate rain rate measurement. The method is independent of the radar calibration and of the attenuation by undetected clouds. This algorithm is also usable as a qualitative hail detector, as well as a detector of anomalous propagation. The goal of the paper is to describe the results of the first experimental implementation of this method using the 35 GHz RABELAIS radar, as attenuated radar, and the 3 GHz CAMRa radar as a reference. We show that the proposed algorithm is stable and enables us to retrieve the actual rain rate even from an observed signal attenuated by more than 30 dB. The results are insensitive to the value used for the power coefficient of the Z(R) relation.

  15. Adaptive Radar Data Quality Control and Ensemble-Based Assimilation for Analyzing and Forecasting High-Impact Weather

    DTIC Science & Technology

    2014-05-22

    Forecasting High-Impact Weather 5a. CONTRACT NUMBER 5b. GRANT NUMBER N000141010778 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) QinXu 5d. PROJECT...Doppler wind information from WSR-88D and Terminal Doppler Weather Radar (TDWR) but also take full advantage of rapid and flexible agile-beam scans...from the phased array radar (PAR) at NWRT. 15. SUBJECT TERMS Weather Radar, Data Ouality Control, Assimilation. 16. SECURITY CLASSIFICATION OF: a

  16. Evaluation of a compound distribution based on weather pattern subsampling for extreme rainfall in Norway

    NASA Astrophysics Data System (ADS)

    Blanchet, J.; Touati, J.; Lawrence, D.; Garavaglia, F.; Paquet, E.

    2015-12-01

    Simulation methods for design flood analyses require estimates of extreme precipitation for simulating maximum discharges. This article evaluates the multi-exponential weather pattern (MEWP) model, a compound model based on weather pattern classification, seasonal splitting and exponential distributions, for its suitability for use in Norway. The MEWP model is the probabilistic rainfall model used in the SCHADEX method for extreme flood estimation. Regional scores of evaluation are used in a split sample framework to compare the MEWP distribution with more general heavy-tailed distributions, in this case the Multi Generalized Pareto Weather Pattern (MGPWP) distribution. The analysis shows the clear benefit obtained from seasonal and weather pattern-based subsampling for extreme value estimation. The MEWP distribution is found to have an overall better performance as compared with the MGPWP, which tends to overfit the data and lacks robustness. Finally, we take advantage of the split sample framework to present evidence for an increase in extreme rainfall in the southwestern part of Norway during the period 1979-2009, relative to 1948-1978.

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

    NASA Astrophysics Data System (ADS)

    Sutherland-Stacey, Luke; Shucksmith, Paul; Austin, Geoff

    2010-05-01

    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 by a personal four wheel drive vehicle or carted by a container truck. Past deployments include the slopes of an erupting volcano, the path of a tropical storm and overwintering in a mountain range. It is well known that sampling and representativeness problems associated with sparse gauge networks and C-band radars can result in high uncertainty in estimates of aerial rainfall. Some of this error is associated with poor sampling of the spatial and temporal scales which are important to precipitation processes. In the case of long range radar, the beam height increase with range also introduces uncertainty when trying to infer precipitation at the ground, even after reflectivity profile correction methods are applied. This paper describes a recently completed field campaign in a hydro power catchment in the North Island of New Zealand. The radar was deployed in a pasture on a farm overlooking the catchment which is about 15km x 10km in size. The catchment is about 150km from the nearest national C-band radar. A number of rain gauges, including high resolution drop counters, were deployed nearby. X-band and comparative C-band radar observations of particular events including orographically initiated convection, frontal systems and widespread rain types are presented. The convective events are characterised by short length scales and rapid evolution, but even the widespread rain has embedded structure. The observations indicate that the evolution time and spatial scales associated with many of the hydrometeors observed in this work precludes aerial estimates being made with sparse

  18. Classification of rainfall events for weather forecasting purposes in andean region of Colombia

    NASA Astrophysics Data System (ADS)

    Suárez Hincapié, Joan Nathalie; Romo Melo, Liliana; Vélez Upegui, Jorge Julian; Chang, Philippe

    2016-04-01

    This work presents a comparative analysis of the results of applying different methodologies for the identification and classification of rainfall events of different duration in meteorological records of the Colombian Andean region. In this study the work area is the urban and rural area of Manizales that counts with a monitoring hydro-meteorological network. This network is composed of forty-five (45) strategically located stations, this network is composed of forty-five (45) strategically located stations where automatic weather stations record seven climate variables: air temperature, relative humidity, wind speed and direction, rainfall, solar radiation and barometric pressure. All this information is sent wirelessly every five (5) minutes to a data warehouse located at the Institute of Environmental Studies-IDEA. With obtaining the series of rainfall recorded by the hydrometeorological station Palogrande operated by the National University of Colombia in Manizales (http://froac.manizales.unal.edu.co/bodegaIdea/); it is with this information that we proceed to perform behavior analysis of other meteorological variables, monitored at surface level and that influence the occurrence of such rainfall events. To classify rainfall events different methodologies were used: The first according to Monjo (2009) where the index n of the heavy rainfall was calculated through which various types of precipitation are defined according to the intensity variability. A second methodology that permitted to produce a classification in terms of a parameter β introduced by Rice and Holmberg (1973) and adapted by Llasat and Puigcerver, (1985, 1997) and the last one where a rainfall classification is performed according to the value of its intensity following the issues raised by Linsley (1977) where the rains can be considered light, moderate and strong fall rates to 2.5 mm / h; from 2.5 to 7.6 mm / h and above this value respectively for the previous classifications. The main

  19. Analysis of the influence of rainfall variables on urban effluents concentrations and fluxes in wet weather

    NASA Astrophysics Data System (ADS)

    Gooré Bi, Eustache; Monette, Frédéric; Gasperi, Johnny

    2015-04-01

    Urban rainfall runoff has been a topic of increasing importance over the past years, a result of both the increase in impervious land area arising from constant urban growth and the effects of climate change on urban drainage. The main goal of the present study is to assess and analyze the correlations between rainfall variables and common indicators of urban water quality, namely event mean concentrations (EMCs) and event fluxes (EFs), in order to identify and explain the impacts of each of the main rainfall variables on the generation process of urban pollutants during wet periods. To perform this analysis, runoff from eight summer rainfall events that resulted in combined sewer overflow (CSO) was sampled simultaneously from two distinct catchment areas in order to quantify discharges at the respective outfalls. Pearson statistical analysis of total suspended solids (TSS), chemical oxygen demand (COD), carbonaceous biochemical oxygen demand at 5 days (CBOD5), total phosphorus (Ptot) and total kedjal nitrogen (N-TKN) showed significant correlations (ρ = 0.05) between dry antecedent time (DAT) and EMCs on one hand, and between total rainfall (TR) and the volume discharged (VD) during EFs, on the other. These results show that individual rainfall variables strongly affect either EMCs or EFs and are good predictors to consider when selecting variables for statistical modeling of urban runoff quality. The results also show that in a combined sewer network, there is a linear relationship between TSS event fluxes and COD, CBOD5, Ptot, and N-TKN event fluxes; this explains 97% of the variability of these pollutants which adsorb onto TSS during wet weather, which therefore act as tracers. Consequently, the technological solution selected for TSS removal will also lead to a reduction of these pollutants. Given the huge volumes involved, urban runoffs contribute substantially to pollutant levels in receiving water bodies, a situation which, in a climate change context, may

  20. The impact of radar data assimilation on the Chorwon-Yonchon 1996 heavy rainfall event

    NASA Astrophysics Data System (ADS)

    Yoo, Hee-Dong

    One of the most effective tools for observing the atmosphere at fine scales is the Doppler radar. In recent years, considerable research has been directed toward using radar data as a component of numerical prediction model initialization, especially at the meso- and storm-scales. In Korea, where locally heavy rainfall events cause tremendous damage and loss of life each year, radar data could be expected to have a significant positive impact on numerical forecast quality. The first step toward testing this hypothesis has been undertaken in the present study, the purpose of which is to assess the impact of WSR-88D radar data assimilation in the numerical forecast of a deadly heavy rainfall event in Korea. We use the CAPS Advanced Regional Prediction System (ARPS), in combination with WSR-88D Level II data gathered by the US Air Force radar in Pyoungtaek, Korea, to generate a series of multi-resolution forecasts. One-way grid nesting is employed, with a horizontal resolution of 27-km for the coarse outer grid, 9-km for the middle grid, and 3-km for the inner fine grid. Incremental analysis updating (IAU) is employed to assimilate radar reflectivity and velocity data on the finest resolution grid, with variations made to the length of the assimilation window, the number of assimilation cycles, the time of model initialization, and various model parameters such as boundary condition update times. A total of twenty six forecasts, two at 27-km, six at 9-km, and eighteen at 3-km resolution, were conducted. Quantitative verification is made against available observations, including accumulated rainfall estimates from the WSR-88D calibrated against surface gauge observations using software from Vieux and Associates, Inc. Our results suggest that radar data assimilation leads to significant improvements in forecast quality as measure by threat, equitable threat, and other quantitative and qualitative measures, though position errors in the maximum observed precipitation

  1. On Utilization of NEXRAD Scan Strategy Information to Infer Discrepancies Associated With Radar and Rain Gauge Surface Volumetric Rainfall Accumulations

    NASA Technical Reports Server (NTRS)

    Roy, Biswadev; Datta, Saswati; Jones, W. Linwood; Kasparis, Takis; Einaudi, Franco (Technical Monitor)

    2000-01-01

    To evaluate the Tropical Rainfall Measuring Mission (TRMM) monthly Ground Validation (GV) rain map, 42 quality controlled tipping bucket rain gauge data (1 minute interpolated rain rates) were utilized. We have compared the gauge data to the surface volumetric rainfall accumulation of NEXRAD reflectivity field, (converting to rain rates using a 0.5 dB resolution smooth Z-R table). The comparison was carried out from data collected at Melbourne, Florida during the month of July 98. GV operational level 3 (L3 monthly) accumulation algorithm was used to obtain surface volumetric accumulations for the radar. The gauge records were accumulated using the 1 minute interpolated rain rates while the radar Volume Scan (VOS) intervals remain less than or equal to 75 minutes. The correlation coefficient for the radar and gauge totals for the monthly time-scale remain at 0.93, however, a large difference was noted between the gauge and radar derived rain accumulation when the radar data interval is either 9 minute, or 10 minute. This difference in radar and gauge accumulation is being explained in terms of the radar scan strategy information. The discrepancy in terms of the Volume Coverage Pattern (VCP) of the NEXRAD is being reported where VCP mode is ascertained using the radar tilt angle information. Hourly radar and gauge accumulations have been computed using the present operational L3 method supplemented with a threshold period of +/- 5 minutes (based on a sensitivity analysis). These radar and gauge accumulations are subsequently improved using a radar hourly scan weighting factor (taking ratio of the radar scan frequency within a time bin to the 7436 total radar scans for the month). This GV procedure is further being improved by introducing a spatial smoothing method to yield reasonable bulk radar to gauge ratio for the hourly and daily scales.

  2. Estimation of Rainfall Kinetic Energy by Rain Intensity and/or Radar Reflectivity Factor

    NASA Astrophysics Data System (ADS)

    Yu, N.; Delrieu, G.; Boudevillain, B.; Hazenberg, P.; Uijlenhoet, R.

    2011-12-01

    This study presents an approach to estimate the rainfall kinetic energy (KE) by rain intensity (R) and radar reflectivity factor (Z) separately, or jointly, on the basis of a one- or two-moment scaled formulation. This formulation considers the raindrop size distribution (DSD) as a combination of bulk rainfall variable(s) (R or/and Z) and an intrinsic distribution g(x), which is in function of the scaled raindrop diameter x. Results from previous studies showed that g(x) remains more or less constant, hence the variability of DSD is mainly explained by the bulk rainfall variable(s). In this study, the Gamma probability density function (pdf) with two parameters is used to model the g(x). Considered the self-consistent relationships between parameters, a robust method is proposed to estimate three climatological g(x), in R-, Z- and RZ-scaled formulation respectively, with a 28-month DSD dataset collected in the Cevennes-Vivarais region, France. Three relationships (KE-R, KE-Z and KE-(R,Z)), which link the observations (R and/or Z) to rainfall kinetic energy (KE), are established based on three climatological g(x). As expected, the combination of R and Z yields a significant improvement of the estimation of KE compared to the single-moment formulations. And Z yields a better performance in KE estimating compared to the KE-R relationship. In terms of the application of these relationships based on real radar reflectivity factors and/or rain gauge measurements, the combination of R and Z yields also the best performance in estimation of KE among the three relationships. Different from the application of the disdrometer data, the performance of the real KE-Z relationship degrades compared to the real KE-R relationship, which is probably due to the sampling error of radar. However, KE estimated by radar possess the advantages in spatialization of kinetic energy over that based on rain gauge stations. This study was supported financially by the HYDRATE project of the

  3. Network connectivity paradigm for the large data produced by weather radar systems

    NASA Astrophysics Data System (ADS)

    Guenzi, Diego; Bechini, Renzo; Boraso, Rodolfo; Cremonini, Roberto; Fratianni, Simona

    2014-05-01

    The traffic over Internet is constantly increasing; this is due in particular to social networks activities but also to the enormous exchange of data caused especially by the so-called "Internet of Things". With this term we refer to every device that has the capability of exchanging information with other devices on the web. In geoscience (and, in particular, in meteorology and climatology) there is a constantly increasing number of sensors that are used to obtain data from different sources (like weather radars, digital rain gauges, etc.). This information-gathering activity, frequently, must be followed by a complex data analysis phase, especially when we have large data sets that can be very difficult to analyze (very long historical series of large data sets, for example), like the so called big data. These activities are particularly intensive in resource consumption and they lead to new computational models (like cloud computing) and new methods for storing data (like object store, linked open data, NOSQL or NewSQL). The weather radar systems can be seen as one of the sensors mentioned above: it transmit a large amount of raw data over the network (up to 40 megabytes every five minutes), with 24h/24h continuity and in any weather condition. Weather radar are often located in peaks and in wild areas where connectivity is poor. For this reason radar measurements are sometimes processed partially on site and reduced in size to adapt them to the limited bandwidth currently available by data transmission systems. With the aim to preserve the maximum flow of information, an innovative network connectivity paradigm for the large data produced by weather radar system is here presented. The study is focused on the Monte Settepani operational weather radar system, located over a wild peak summit in north-western Italy.

  4. Estimating reflectivity values from wind turbines for analyzing the potential impact on weather radar services

    NASA Astrophysics Data System (ADS)

    Angulo, I.; Grande, O.; Jenn, D.; Guerra, D.; de la Vega, D.

    2015-02-01

    The World Meteorological Organization (WMO) has repeatedly expressed concern over the increasing number of impact cases of wind turbine farms on weather radars. Since nowadays signal processing techniques to mitigate Wind Turbine Clutter (WTC) are scarce, the most practical approach to this issue is the assessment of the potential interference from a wind farm before it is installed. To do so, and in order to obtain a WTC reflectivity model, it is crucial to estimate the Radar Cross Section (RCS) of the wind turbines to be built, which represents the power percentage of the radar signal that is backscattered to the radar receiver. This paper first characterizes the RCS of wind turbines in the weather radar frequency bands by means of computer simulations based on the Physical Optics theory, and then proposes a simplified model to estimate wind turbine RCS values. This model is of great help in the evaluation of the potential impact of a certain wind farm on the weather radar operation.

  5. Evaluation of a compound distribution based on weather patterns subsampling for extreme rainfall in Norway

    NASA Astrophysics Data System (ADS)

    Blanchet, J.; Touati, J.; Lawrence, D.; Garavaglia, F.; Paquet, E.

    2015-06-01

    Simulation methods for design flood analyses require estimates of extreme precipitation for simulating maximum discharges. This article evaluates the MEWP model, a compound model based on weather pattern classification, seasonal splitting and exponential distributions, for its suitability for use in Norway. The MEWP model is the probabilistic rainfall model used in the SCHADEX method for extreme flood estimation. Regional scores of evaluation are used in a split sample framework to compare the MEWP distribution with more general heavy-tailed distributions, in this case the Multi Generalized Pareto Weather Pattern (MGPWP) distribution. The analysis shows the clear benefit obtained from seasonal and weather pattern-based subsampling for extreme value estimation. The MEWP distribution is found to have an overall better performance as compared with the MGPWP, which tends to overfit the data and lacks robustness. Finally, we take advantage of the split sample framework to present evidence for an increase in extreme rainfall in the south-western part of Norway during the period 1979-2009, relative to 1948-1978.

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

    PubMed

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

    2008-07-01

    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.

  7. Partly cloudy with a chance of migration: Weather, radars, and aeroecology

    USGS Publications Warehouse

    Chilson, Phillip B.; Frick, Winifred F.; Kelly, Jeffrey F.; Howard, Kenneth W.; Larkin, Ronald P.; Diehl, Robert H.; Westbrook, John K.; Kelly, T. Adam; Kunz, Thomas H.

    2012-01-01

    Aeroecology is an emerging scientific discipline that integrates atmospheric science, Earth science, geography, ecology, computer science, computational biology, and engineering to further the understanding of biological patterns and processes. The unifying concept underlying this new transdisciplinary field of study is a focus on the planetary boundary layer and lower free atmosphere (i.e., the aerosphere), and the diversity of airborne organisms that inhabit and depend on the aerosphere for their existence. Here, we focus on the role of radars and radar networks in aeroecological studies. Radar systems scanning the atmosphere are primarily used to monitor weather conditions and track the location and movements of aircraft. However, radar echoes regularly contain signals from other sources, such as airborne birds, bats, and arthropods. We briefly discuss how radar observations can be and have been used to study a variety of airborne organisms and examine some of the many potential benefits likely to arise from radar aeroecology for meteorological and biological research over a wide range of spatial and temporal scales. Radar systems are becoming increasingly sophisticated with the advent of innovative signal processing and dual-polarimetric capabilities. These capabilities should be better harnessed to promote both meteorological and aeroecological research and to explore the interface between these two broad disciplines. We strongly encourage close collaboration among meteorologists, radar scientists, biologists, and others toward developing radar products that will contribute to a better understanding of airborne fauna.

  8. Wideband Waveform Design principles for Solid-state Weather Radars

    SciTech Connect

    Bharadwaj, Nitin; Chandrasekar, V.

    2012-01-01

    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.

  9. Use of Historical Radar Rainfall Estimates to Develop Design Storms in Los Angeles.

    NASA Astrophysics Data System (ADS)

    Curtis, D. C.; Humphrey, J.; Moffitt, J.

    2007-12-01

    A database of 15-minute historical gage adjusted radar-rainfall estimates was used to evaluate the geometric properties of storms in the City of Los Angeles, CA. The database includes selected months containing significant rainfall during the period 1996-2007. For each time step, areas of contiguous rainfall were identified as individual storm cells. An idealized ellipse was fit to each storm cell and the properties of the ellipse (e.g., size, shape, orientation, velocity and other parameters) were recorded. To accurately account for the range of storm cell sizes, capture a large number of storm cells in a climatologically similar area, assess the variability of storm movement, and minimize the impact of edge effects (i.e., incomplete coverage of cells entering and leaving), a study area substantially larger than the City of Los Angeles was used. The study area extends from city center to 30 miles north to the crest of San Gabriel Mountains, 45 miles east to Ontario, 60 miles south to Santa Catalina Island, and 70 miles west to Oxnard, an area of about10,000 square miles. Radar data for this area over 30 months in the study yields many thousands of storm cells for analysis. Storms were separated into classes by origin, direction and speed of movement. Preliminary investigations considers three types: Arctic origin (west-northwest), Pacific origin (southwest) and Tropical origin (south or stationary). Radar data (for 1996-2007) and upper air maps (1948-2006) are used to identify the direction and speed of significant precipitation events. Typical duration and temporal patterns of Los Angeles historical storms were described by season and storm type. Time of maximum intensity loading variation were determined for a selection of historic storms Depth-Areal Reduction Factors (DARF) for cloudbursts were developedfrom the radar data. These data curves are fit to equations showing the relationships between DARF, area and central intensity. Separate DARF curves are

  10. A System Concept for the Advanced Post-TRMM Rainfall Profiling Radars

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Smith, Eric A.

    1998-01-01

    Atmospheric latent heating field is fundamental to all modes of atmospheric circulation and upper mixed layer circulations of the ocean. The key to understanding the atmospheric heating process is understanding how and where precipitation occurs. The principal atmospheric processes which link precipitation to atmospheric circulation include: (1) convective mass fluxes in the form of updrafts and downdrafts; (2) microphysical. nucleation and growth of hydrometeors; and (3) latent heating through dynamical controls on the gravitation-driven vertical mass flux of precipitation. It is well-known that surface and near-surface rainfall are two of the key forcing functions on a number of geophysical parameters at the surface-air interface. Over ocean, rainfall variation contributes to the redistribution of water salinity, sea surface temperature, fresh water supply, and marine biology and eco-system. Over land, rainfall plays a significant role in rainforest ecology and chemistry, land hydrology and surface runoff. Precipitation has also been closely linked to a number of atmospheric anomalies and natural hazards that occur at various time scales, including hurricanes, cyclones, tropical depressions, flash floods, droughts, and most noticeable of all, the El Ninos. From this point of view, the significance of global atmospheric precipitation has gone far beyond the science arena - it has a far-reaching impact on human's socio-economic well-being and sustenance. These and many other science applications require the knowledge of, in a global basis, the vertical rain structures, including vertical motion, rain intensity, differentiation of the precipitating hydrometeors' phase state, and the classification of mesoscale physical structure of the rain systems. The only direct means to obtain such information is the use of a spaceborne profiling radar. It is important to mention that the Tropical Rainfall Measuring Mission (TRMM) have made a great stride forward towards this

  11. On Rainfall Modification by Major Urban Areas. Part 1; Observations from Space-borne Rain Radar Aboard TRMM

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshell; Starr, David OC. (Technical Monitor)

    2001-01-01

    A novel approach is introduced to correlating urbanization and rainfall modification. This study represents one of the first published attempts (possibly the first) to identify and quantify rainfall modification by urban areas using satellite-based rainfall measurements. Previous investigations successfully used rain gauge networks and around-based radar to investigate this phenomenon but still encountered difficulties due to limited, specialized measurements and separation of topographic and other influences. Three years of mean monthly rainfall rates derived from the first space-based rainfall radar, Tropical Rainfall Measuring Mission's (TRMM) Precipitation Radar, are employed. Analysis of data at half-degree latitude resolution enables identification of rainfall patterns around major metropolitan areas of Atlanta, Montgomery, Nashville, San Antonio, Waco, and Dallas during the warm season. Preliminary results reveal an average increase of 5.6% in monthly rainfall rates (relative to a mean upwind CONTROL area) over the metropolis but an average increase of approx. 28%, in monthly rainfall rates within 30-60 kilometers downwind of the metropolis. Some portions of the downwind area exhibit increases as high as 51%. It was also found that maximum rainfall rates found in the downwind impact area exceeded the mean value in the upwind CONTROL area by 48%-116% and were generally found at an average distance of 39 km from the edge of the urban center or 64 km from the center of the city. These results are quite consistent studies of St. Louis (e.g' METROMEX) and Chicago almost two decades ago and more recent studies in the Atlanta and Mexico City areas.

  12. The value of weather radar data for the estimation of design storms - an analysis for the Hannover region

    NASA Astrophysics Data System (ADS)

    Haberlandt, Uwe; Berndt, Christian

    2016-05-01

    Pure radar rainfall, station rainfall and radar-station merging products are analysed regarding extreme rainfall frequencies with durations from 5 min to 6 h and return periods from 1 year to 30 years. Partial duration series of the extremes are derived from the data and probability distributions are fitted. The performance of the design rainfall estimates is assessed based on cross validations for observed station points, which are used as reference. For design rainfall estimation using the pure radar data, the pixel value at the station location is taken; for the merging products, spatial interpolation methods are applied. The results show, that pure radar data are not suitable for the estimation of extremes. They usually lead to an overestimation compared to the observations, which is opposite to the usual behaviour of the radar rainfall. The merging products between radar and station data on the other hand lead usually to an underestimation. They can only outperform the station observations for longer durations. The main problem for a good estimation of extremes seems to be the poor radar data quality.

  13. Worldwide Weather Radar Imagery May Allow Substantial Increase in Meteorite Fall Recovery

    NASA Technical Reports Server (NTRS)

    Fries, Marc; Matson, Robert; Schaefer, Jacob; Fries, Jeffery; Hankey, Mike; Anderson, Lindsay

    2014-01-01

    Weather radar imagery is a valuable new technique for the rapid recovery of meteorite falls, to include falls which would not otherwise be recovered (e.g. Battle Mountain). Weather radar imagery reveals about one new meteorite fall per year (18 falls since 1998), using weather radars in the United States alone. However, an additional 75 other nations operate weather radar networks according to the UN World Meteorological Organization (WMO). If the imagery of those radars were analyzed, the current rate of meteorite falls could be improved considerably, to as much as 3.6 times the current recovery rate based on comparison of total radar areal coverage. Recently, the addition of weather radar imagery, seismometry and internet-based aggregation of eyewitness reports has improved the speed and accuracy of fresh meteorite fall recovery [e.g. 1,2]. This was demonstrated recently with the radar-enabled recovery of the Sutter's Mill fall [3]. Arguably, the meteorites recovered via these methods are of special scientific value as they are relatively unweathered, fresh falls. To illustrate this, a recent SAO/NASA ADS search using the keyword "meteorite" shows that all 50 of the top search results included at least one named meteorite recovered from a meteorite fall. This is true even though only 1260 named meteorite falls are recorded among the >49,000 individual falls recorded in the Meteoritical Society online database. The US NEXRAD system used thus far to locate meteorite falls covers most of the United States' surface area. Using a WMO map of the world's weather radars, we estimate that the total coverage of the other 75 national weather radar networks equals about 3.6x NEXRAD's coverage area. There are two findings to draw from this calculation: 1) For the past 16 years during which 18 falls are seen in US radar data, there should be an additional 65 meteorite falls recorded in worldwide radar imagery. Also: 2) if all of the world's radar data could be analyzed, the

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

    NASA Astrophysics Data System (ADS)

    Borga, M.; Creutin, J. D.

    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.

  15. Comparison of Radar Rainfall Retrieval Algorithms in Convective Rain During TOGA COARE

    NASA Technical Reports Server (NTRS)

    Durden, Stephen L.; Haddad, Z. S.

    1998-01-01

    The authors compare deterministic and stochastic rain-rate retrieval algorithms by applying them to 14-GHz nadir-looking airborne radar reflectivity profiles acquired in tropical convective rain during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, The deterministic algorithms both use the path-integrated attenuation (PIA), measured by the surface reference technique, as a constraint. One deterministic algorithm corrects the k-R relation, while the second corrects the Z-R relation. The stochastic algorithms are based on applying an extended Kalman filter to the reflectivity profile. One employs radar reflectivity only; the other additionally uses the PIA. The authors find that the stochastic algorithm, which uses the PIA, is the most robust algorithm with regard to incorrect assumptions about the drop size distribution (DSD). The deterministic algorithm that uses the PIA to adjust the Z-R relation is also fairly robust and produces rain rates similar to the stochastic algorithm that uses the PIA, The deterministic algorithm that adjusts only the k-R relation and the stochastic radar-only algorithm are more sensitive to assumptions about the DSD. It is likely that they underestimate convective rainfall, especially if the DSD is erroneously assumed to be appropriate for stratiform rain conditions.

  16. Comparison between weather radar and rain gauges data of precipitations that triggered debris flows in the Dolomites (North Eastern Italian Alps)

    NASA Astrophysics Data System (ADS)

    Bernard, Martino; Gregoretti, Carlo

    2016-04-01

    High intensity and short duration (usually 15-30 minutes) rainfalls are able to generate sudden and abundant runoff in rocky cliffs that can entrain large quantities of sediments and originate debris flow phenomena. A rain gauge network has been set up in two different areas of Dolomites (North Eastern Italian Alps) far each other about 15 km: Fiames (Cortina d'Ampezzo) and Rovina di Cancia (Borca di Cadore). The first network is composed of 9 rain gauges in an area of 1 km2, while the second is composed of 6 rain gauges in an area of 2 km2. In both the areas, the rain gauges are positioned both upstream and downstream the initiation areas of the occurring debris flows. Another single rain gauge is positioned close to the initiation area of Rudavoi debris flow (Auronzo di Cadore) and is far about 5 km from the Fiames rain gauges network. All the rain gauges sample precipitation depth at 5 minutes intervals. In the years 2009-2015 records of rainfalls that triggered 22 debris flows were taken. In most cases, the recorded rainfalls show an higher variability both along distance (200-500 m) and along altitude (200-600 m). Precipitation data recorded by the rain gauges are then compared with those estimated by means of a C-Band weather radar about 70 km away from there, to verify the possible interchangeability of the two measurement systems. Rainfall depths estimated by radar are provided with the temporal interval of the rain gauges (5 minutes) but with a different spatial scale (500 x 500 m raster resolution). To avoid the observation scale gap between the different techniques, in addition to standard comparisons between point gauge and radar rainfall measures, mean areal precipitations were derived from rain gauge network and compared with radar data. Results seem to demonstrate that radar tends to underestimate precipitation evaluated from rain gauges network, both on different measurement scales and on mean spatial data. On average, underestimation regards both

  17. Effect of simulated rainfall and weathering on release of preservative elements from CCA treated wood.

    PubMed

    Lebow, Stan; Williams, R Sam; Lebow, Patricia

    2003-09-15

    The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium from CCA-treated wood exposed to simulated rainfall. Deck boards treated with CCA were either left unfinished or dipped in a finish prepared with 1%, 3%, or 5% water repellent. All specimens were exposed to leaching from simulated rainfall, and a subset of specimens was also exposed to UV radiation. The rainfall was collected and analyzed for total elemental arsenic, copper, and chromium. The water repellent significantly decreased the amounts of these elements in the runoff, but for the short duration of this study there was no difference among the three water repellent concentrations. It is possible that water repellent content would have a greater effect over a longer exposure period. Exposure to UV radiation caused a significant increase in leaching from both finished and unfinished specimens. This effect may be a result of increased surface area during weathering as well as loss of fibers caused by UV-induced surface erosion.

  18. Navigation errors encountered using weather-mapping radar for helicopter IFR guidance to oil rigs

    NASA Technical Reports Server (NTRS)

    Phillips, J. D.; Bull, J. S.; Hegarty, D. M.; Dugan, D. C.

    1980-01-01

    In 1978 a joint NASA-FAA helicopter flight test was conducted to examine the use of weather-mapping radar for IFR guidance during landing approaches to oil rig helipads. The following navigation errors were measured: total system error, radar-range error, radar-bearing error, and flight technical error. Three problem areas were identified: (1) operational problems leading to pilot blunders, (2) poor navigation to the downwind final approach point, and (3) pure homing on final approach. Analysis of these problem areas suggests improvement in the radar equipment, approach procedure, and pilot training, and gives valuable insight into the development of future navigation aids to serve the off-shore oil industry.

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

    NASA Technical Reports Server (NTRS)

    Evans, James E.

    1988-01-01

    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.

  20. On Rainfall Modification by Major Urban Areas. Part 1; Observations from Space-borne Rain Radar on TRMM

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall; Pierce, Harold; Starr, David OC. (Technical Monitor)

    2001-01-01

    This study represents one of the first published attempts to identify rainfall modification by urban areas using satellite-based rainfall measurements. Data from the first space-based rain-radar, the Tropical Rainfall Measuring Mission's (TRMM) Precipitation Radar, are employed. Analysis of the data enables identification of rainfall patterns around Atlanta, Montgomery, Nashville, San Antonio, Waco, and Dallas during the warm season. Results reveal an average increase of -28% in monthly rainfall rates within 30-60 kilometers downwind of the metropolis with a modest increase of 5.6% over the metropolis. Portions of the downwind area exhibit increases as high as 51%. The percentage chances are relative to an upwind CONTROL area. It was also found that maximum rainfall rates in the downwind impact area can exceed the mean value in the upwind CONTROL area by 48%-116%. The maximum value was generally found at an average distance of 39 km from the edge of the urban center or 64 km from the center of the city. These results are consistent with METROMEX studies of St. Louis almost two decades ago and more recent studies near Atlanta. Future work will investi(yate hypothesized factors causing rainfall modification by urban areas. Additional work is also needed to provide more robust validation of space-based rain estimates near major urban areas. Such research has implications for urban planning, water resource management, and understanding human impact on the environment.

  1. National Scale Rainfall Map Based on Linearly Interpolated Data from Automated Weather Stations and Rain Gauges

    NASA Astrophysics Data System (ADS)

    Alconis, Jenalyn; Eco, Rodrigo; Mahar Francisco Lagmay, Alfredo; Lester Saddi, Ivan; Mongaya, Candeze; Figueroa, Kathleen Gay

    2014-05-01

    In response to the slew of disasters that devastates the Philippines on a regular basis, the national government put in place a program to address this problem. The Nationwide Operational Assessment of Hazards, or Project NOAH, consolidates the diverse scientific research being done and pushes the knowledge gained to the forefront of disaster risk reduction and management. Current activities of the project include installing rain gauges and water level sensors, conducting LIDAR surveys of critical river basins, geo-hazard mapping, and running information education campaigns. Approximately 700 automated weather stations and rain gauges installed in strategic locations in the Philippines hold the groundwork for the rainfall visualization system in the Project NOAH web portal at http://noah.dost.gov.ph. The system uses near real-time data from these stations installed in critical river basins. The sensors record the amount of rainfall in a particular area as point data updated every 10 to 15 minutes. The sensor sends the data to a central server either via GSM network or satellite data transfer for redundancy. The web portal displays the sensors as a placemarks layer on a map. When a placemark is clicked, it displays a graph of the rainfall data for the past 24 hours. The rainfall data is harvested by batch determined by a one-hour time frame. The program uses linear interpolation as the methodology implemented to visually represent a near real-time rainfall map. The algorithm allows very fast processing which is essential in near real-time systems. As more sensors are installed, precision is improved. This visualized dataset enables users to quickly discern where heavy rainfall is concentrated. It has proven invaluable on numerous occasions, such as last August 2013 when intense to torrential rains brought about by the enhanced Southwest Monsoon caused massive flooding in Metro Manila. Coupled with observations from Doppler imagery and water level sensors along the

  2. COSMO-SkyMed measurements in precipitation over the sea: analysis of Louisiana summer thunderstorms by simultaneous weather radar observations

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Radar signatures of rain cells are investigated using X-band synthetic aperture radar (X-SAR) images acquired from COSMO-SkyMed constellation over oceans off the coast of Louisiana in summer 2010 provided by ASI archive. COSMO-SkyMed (CSK) monitoring of Deepwater Horizon oil spill provided a big amount of data during the period April-September 2010 and in July-August when several thunderstorms occurred in that area. In X-SAR images, radar signatures of rain cells over the sea usually consist of irregularly shaped bright and dark patches. These signatures originate from 1) the scattering and attenuation of radiation by hydrometers in the rain cells and 2) the modification of the sea roughness induced by the impact of raindrops and by wind gusts associated with rain cell. However, the interpretation of precipitation signatures in X-SAR images is not completely straightforward, especially over sea. Coincident measurements from ground based radars and an electromagnetic (EM) model predicting radar returns from the sea surface corrugated by rainfall are used to support the analysis. A dataset consisting of 4 CSK images has been collected over Gulf of Mexico while a WSR-88D NEXRAD S-band Doppler radar (KLIX) located in New Orleans was scanning the nearby portion of ocean. Terrestrial measurements have been used to reconstruct the component of X-SAR returns due to precipitation by modifying the known technique applied on measurements over land (Fritz et al. 2010, Baldini et al. 2011). Results confirm that the attenuation signature in X-SAR images collected over land, particularly pronounced in the presence of heavy precipitation cells, can be related to the S-band radar reflectivity integrated along the same path. The Normalized Radar Cross Section (NRCS) of land is considered to vary usually up to a few dBs in case of rain but with strong dependency on the specific type and conditions of land cover. While the NRCS of sea surface in clear weather condition can be

  3. A Weather Radar Simulator for the Evaluation of Polarimetric Phased Array Performance

    SciTech Connect

    Byrd, Andrew D.; Ivic, Igor R.; Palmer, Robert D.; Isom, Bradley M.; Cheong, Boon Leng; Schenkman, Alexander D.; Xue, Ming

    2016-07-01

    A radar simulator capable of generating time series data for a polarimetric phased array weather radar has been designed and implemented. The received signals are composed from a high-resolution numerical prediction weather model. Thousands of scattering centers, each with an independent randomly generated Doppler spectrum, populate the field of view of the radar. The moments of the scattering center spectra are derived from the numerical weather model, and the scattering center positions are updated based on the three-dimensional wind field. In order to accurately emulate the effects of the system-induced cross-polar contamination, the array is modeled using a complete set of dual-polarization radiation patterns. The simulator offers reconfigurable element patterns and positions as well as access to independent time series data for each element, resulting in easy implementation of any beamforming method. It also allows for arbitrary waveform designs and is able to model the effects of quantization on waveform performance. Simultaneous, alternating, quasi-simultaneous, and pulse-to-pulse phase coded modes of polarimetric signal transmission have been implemented. This framework allows for realistic emulation of the effects of cross-polar fields on weather observations, as well as the evaluation of possible techniques for the mitigation of those effects.

  4. Time-lapse borehole radar for monitoring rainfall infiltration through podosol horizons in a sandy vadose zone

    NASA Astrophysics Data System (ADS)

    Strobach, Elmar; Harris, B. D.; Dupuis, J. C.; Kepic, A. W.

    2014-03-01

    The shallow aquifer on the Gnangara Mound, north of Perth, Western Australia, is recharged by winter rainfall. Water infiltrates through a sandy Podosol where cemented accumulation (B-) horizons are common. They are water retentive and may impede recharge. To observe wetting fronts and the influence of soil horizons on unsaturated flow, we deployed time-lapse borehole radar techniques sensitive to soil moisture variations during an annual recharge cycle. Zero-offset crosswell profiling (ZOP) and vertical radar profiling (VRP) measurements were performed at six sites on a monthly basis before, during, and after annual rainfall in 2011. Water content profiles are derived from ZOP logs acquired in closely spaced wells. Sites with small separation between wells present potential repeatability and accuracy difficulties. Such problems could be lessened by (i) ZOP saturated zone velocity matching of time-lapse curves, and (ii) matching of ZOP and VRP results. The moisture contents for the baseline condition and subsequent observations are computed using the Topp relationship. Time-lapse moisture curves reveal characteristic vadose zone infiltration regimes. Examples are (I) full recharge potential after 200 mm rainfall, (II) delayed wetting and impeded recharge, and (III) no recharge below 7 m depth. Seasonal infiltration trends derived from long-term time-lapse neutron logging at several sites are shown to be comparable with infiltration trends recovered from time-lapse crosswell radar measurements. However, radar measurements sample a larger volume of earth while being safer to deploy than the neutron method which employs a radioactive source. For the regime (III) site, where time-lapse radar indicates no net recharge or zero flux to the water table, a simple water balance provides an evapotranspiration value of 620 mm for the study period. This value compares favorably to previous studies at similar test sites in the region. Our six field examples demonstrate

  5. Predicting combined sewer overflows chamber depth using artificial neural networks with rainfall radar data.

    PubMed

    Mounce, S R; Shepherd, W; Sailor, G; Shucksmith, J; Saul, A J

    2014-01-01

    Combined sewer overflows (CSOs) represent a common feature in combined urban drainage systems and are used to discharge excess water to the environment during heavy storms. To better understand the performance of CSOs, the UK water industry has installed a large number of monitoring systems that provide data for these assets. This paper presents research into the prediction of the hydraulic performance of CSOs using artificial neural networks (ANN) as an alternative to hydraulic models. Previous work has explored using an ANN model for the prediction of chamber depth using time series for depth and rain gauge data. Rainfall intensity data that can be provided by rainfall radar devices can be used to improve on this approach. Results are presented using real data from a CSO for a catchment in the North of England, UK. An ANN model trained with the pseudo-inverse rule was shown to be capable of predicting CSO depth with less than 5% error for predictions more than 1 hour ahead for unseen data. Such predictive approaches are important to the future management of combined sewer systems.

  6. Least square spline decomposition in time-frequency analysis of weather radar signals

    NASA Astrophysics Data System (ADS)

    Shelevytska, K. I.; Semenova, O. S.; Shelevytsky, I. V.; Yanovsky, F. J.

    2011-10-01

    Meteorology plays an important role in aviation, as it enables to predict weather conditions and detect flight dangerous meteorological phenomena. Meteorological radar is used to detect the intensity and possible location of precipitation and dangerous zones in them. Doppler radar systems are able to measure the speed of scatteres that constitute meteorological formations and phenomena. The tasks of measurement accuracy increasing and reliability rise of hazardous meteorological phenomena detection become much more relevant after establishing new flight control system CNS ATM adopted by ICAO - the International Civil Aviation Organization.

  7. The Boston Area NEXRAD (Next Generation Weather Radar) Demonstration (BAND).

    DTIC Science & Technology

    1985-05-08

    R164 426 THE BOSTON ARES NEXRAD (NEXT NERTION WEATHER RAA) 1/K DENONSTRATION (BRND)(U) AIR FORCE GEOPHYSICS LR HANSCOM RFB MA D E FORSYTH ET AL. 08...8217 ""’""’"-’ -:"-"."ŕ"൓’ - - .6 AD-A164 426 AFGL-TR-85-0098 ENVIRONMENTAL RESEARCH PAPERS, NO. 912 The Boston Area NEXRAD Demonstration (BAND) DOUGLAS E. FORSYTH...CO - NEXRAD JOINT SYSTEM PROGRAM OFFICE SILVER SPRING, MD 20900 LNEDJ. 86 221 015’ .... . - .-... -- .. "..".... "This technical report has been

  8. Spatial-Temporal Evolution of Water Vapor during a Heavy Rain Detected by InSAR, GPS and Weather Radar

    NASA Astrophysics Data System (ADS)

    Kinoshita, Y.; shimada, M.; Furuya, M.

    2011-12-01

    SAR revealed a rapid decrease in the amount of about 4 cm for 2 hours before SAR data was acquired. Additionally, we generated weather radar (WR) echo image at the moment of SAR data acquisition to compare this with the InSAR and GPS data. In the WR image, the small area with rainfall intensity greater than 80 mm/h exists at the location of tropospheric signal in InSAR. We will discuss what we can learn from InSAR, GPS and WR data.

  9. Improvement of forecast skill for severe weather by merging radar-based extrapolation and storm-scale NWP corrected forecast

    NASA Astrophysics Data System (ADS)

    Wang, Gaili; Wong, Wai-Kin; Hong, Yang; Liu, Liping; Dong, Jili; Xue, Ming

    2015-03-01

    The primary objective of this study is to improve the performance of deterministic high resolution rainfall forecasts caused by severe storms by merging an extrapolation radar-based scheme with a storm-scale Numerical Weather Prediction (NWP) model. Effectiveness of Multi-scale Tracking and Forecasting Radar Echoes (MTaRE) model was compared with that of a storm-scale NWP model named Advanced Regional Prediction System (ARPS) for forecasting a violent tornado event that developed over parts of western and much of central Oklahoma on May 24, 2011. Then the bias corrections were performed to improve the forecast accuracy of ARPS forecasts. Finally, the corrected ARPS forecast and radar-based extrapolation were optimally merged by using a hyperbolic tangent weight scheme. The comparison of forecast skill between MTaRE and ARPS in high spatial resolution of 0.01° × 0.01° and high temporal resolution of 5 min showed that MTaRE outperformed ARPS in terms of index of agreement and mean absolute error (MAE). MTaRE had a better Critical Success Index (CSI) for less than 20-min lead times and was comparable to ARPS for 20- to 50-min lead times, while ARPS had a better CSI for more than 50-min lead times. Bias correction significantly improved ARPS forecasts in terms of MAE and index of agreement, although the CSI of corrected ARPS forecasts was similar to that of the uncorrected ARPS forecasts. Moreover, optimally merging results using hyperbolic tangent weight scheme further improved the forecast accuracy and became more stable.

  10. Mass discharge rate retrieval combining weather radar and thermal camera observations

    NASA Astrophysics Data System (ADS)

    Vulpiani, Gianfranco; Ripepe, Maurizio; Valade, Sebastien

    2016-08-01

    The mass discharge rate is a key parameter for initializing volcanic ash dispersal models. Commonly used empirical approaches derive the discharge rate by the plume height as estimated by remote sensors. A novel approach based on the combination of weather radar observations and thermal camera imagery is presented here. It is based on radar ash concentration estimation and the retrieval of the vertical exit velocities of the explosive cloud using thermal camera measurements. The applied radar retrieval methodology is taken from a revision of previously presented work. Based on the analysis of four eruption events of the Mount Etna volcano (Sicily, Italy) that occurred in December 2015, the proposed methodology is tested using observations collected by three radar systems (at C and X band) operated by the Italian Department of Civil Protection. The total erupted mass was estimated to be about 9·109 kg and 2.4·109 kg for the first and second events, respectively, while it was about 1.2·109 kg for both the last two episodes. The comparison with empirical approaches based on radar-retrieved plume height shows a reasonably good agreement. Additionally, the comparative analysis of the polarimetric radar measurements provides interesting information on the vertical structure of the ash plume, including the size of the eruption column and the height of the gas thrust region.

  11. Earthquake Weather: Linking Seismicity to Changes in Barometric Pressure, Earth Tides, and Rainfall

    NASA Astrophysics Data System (ADS)

    West, J. D.; Garnero, E.; Shirzaei, M.

    2015-12-01

    It has been widely observed that earthquakes can be triggered due to changes in stress induced by the passage of surface waves from remote earthquakes. These stress changes are typically on the order of a few kiloPascals and occur over time spans of seconds. Less well investigated is the question of whether triggering of seismic activity can result from similar stress changes occurring over periods of hours or days due to changing barometric pressure, rainfall, and Earth tides. Past studies have shown a possible link between these stress sources and slow earthquakes in Taiwan (Hsu et al., 2015). Here, we investigate the relationship between seismicity and changing barometric pressure, Earth tides, and rainfall for four regions of the western United States where regional seismic networks provide high-quality seismic catalogs over relatively long time periods: Southern California, Northern California, the Pacific Northwest, and Utah. For each region we obtained seismic catalogs from January 2001 through September 2014 and acquired hourly data for barometric pressure and rainfall across the regions from the National Climatic Data Center. The vertical stress time series due to Earth tides was computed for the location of each weather station in the study areas. We summed the stresses from these 3 sources and looked for variations in seismicity correlated to the stress changes. We show that seismicity rates increase with increasing magnitude of stress change. In many cases the increase in seismicity is larger for reductions in vertical stress than it is for stress increases. We speculate that the dependency of seismic rate on combined vertical stress is acting through a combination of two mechanisms: (1) Reduced stresses reduce the normal force on faults, triggering failure in critically-stressed faults. (2) Increased stresses may similarly reduce the normal force on faults due to increases in pore pressure induced in the fault region.

  12. Development and flight test of a weather radar precision approach concept

    NASA Technical Reports Server (NTRS)

    Clary, G. R.; Anderson, D. J.; Chisholm, J. P.

    1984-01-01

    In order to make full use of the helicopter's unique capability of remote-site, off-airport landings, it would be desirable to employ a self-contained navigation system requiring minimum groundable-based equipment. For this reason, research is being conducted with the aim to develop the use of airborne weather radar as a primary navigation aid for helicopter approach and landing in instrument flight rules (IFR) conditions. Anderson et al. (1982) have reported about the first phase of this effort, taking into account the detection of passive ground-based corner reflectors with the aid of an 'echo processor'. The technology of passive-reflector detection in the overland environment provides the pilot with the range and bearing to the landing site. The present investigation is concerned with a second research phase, which was undertaken with the objective to develop and demonstrate the feasibility of a weather radar-based precision approach concept. Preliminary flight test results are considered.

  13. Wind from Indian Doppler Weather Radars: a data assimilation view point

    NASA Astrophysics Data System (ADS)

    Dutta, Devajyoti; Mallick, Swapan; Jyothi, K. A.; George, John P.; Kumar, D. Preveen

    2016-05-01

    Doppler Weather Radar (DWR) can provide tropospheric wind observations with high temporal and spatial resolutions. The Volume Velocity Processing (VVP) technique is one of the processing methods which can provide vertical profiles of mean horizontal winds. The DWR observed VVP winds gives a continuous observation of the wind field at various atmospheric levels. The quality of the VVP winds is studied against the short-range forecast of the NCUM model (model background). The biases of the observation are calculated against model background. This study focuses on the quality of VVP winds and seasonal variation of bias of the observed wind. This results shows that the VVP winds provides reasonably accurate estimates of the vertical wind structure in the troposphere over radar locations which can be effectively used in the numerical weather prediction system.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  15. Under the Weather: Health, Schooling, and Economic Consequences of Early-Life Rainfall. NBER Working Paper No. 14031

    ERIC Educational Resources Information Center

    Maccini, Sharon L.; Yang, Dean

    2008-01-01

    How sensitive is long-run individual well-being to environmental conditions early in life? This paper examines the effect of weather conditions around the time of birth on the health, education, and socioeconomic outcomes of Indonesian adults born between 1953 and 1974. We link historical rainfall for each individual's birth-year and…

  16. Flight investigation of helicopter IFR approaches to oil rigs using airborne weather and mapping radar

    NASA Technical Reports Server (NTRS)

    Bull, J. S.; Hegarty, D. M.; Phillips, J. D.; Sturgeon, W. R.; Hunting, A. W.; Pate, D. P.

    1979-01-01

    Airborne weather and mapping radar is a near-term, economical method of providing 'self-contained' navigation information for approaches to offshore oil rigs and its use has been rapidly expanding in recent years. A joint NASA/FAA flight test investigation of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico was initiated in June 1978 and conducted under contract to Air Logistics. Approximately 120 approaches were flown in a Bell 212 helicopter by 15 operational pilots during the months of August and September 1978. The purpose of the tests was to collect data to (1) support development of advanced radar flight director concepts by NASA and (2) aid the establishment of Terminal Instrument Procedures (TERPS) criteria by the FAA. The flight test objectives were to develop airborne radar approach procedures, measure tracking errors, determine accpetable weather minimums, and determine pilot acceptability. Data obtained will contribute significantly to improved helicopter airborne radar approach capability and to the support of exploration, development, and utilization of the Nation's offshore oil supplies.

  17. Forward Looking Radar Imaging by Truncated Singular Value Decomposition and Its Application for Adverse Weather Aircraft Landing.

    PubMed

    Huang, Yulin; Zha, Yuebo; Wang, Yue; Yang, Jianyu

    2015-06-18

    The forward looking radar imaging task is a practical and challenging problem for adverse weather aircraft landing industry. Deconvolution method can realize the forward looking imaging but it often leads to the noise amplification in the radar image. In this paper, a forward looking radar imaging based on deconvolution method is presented for adverse weather aircraft landing. We first present the theoretical background of forward looking radar imaging task and its application for aircraft landing. Then, we convert the forward looking radar imaging task into a corresponding deconvolution problem, which is solved in the framework of algebraic theory using truncated singular decomposition method. The key issue regarding the selecting of the truncated parameter is addressed using generalized cross validation approach. Simulation and experimental results demonstrate that the proposed method is effective in achieving angular resolution enhancement with suppressing the noise amplification in forward looking radar imaging.

  18. Forward Looking Radar Imaging by Truncated Singular Value Decomposition and Its Application for Adverse Weather Aircraft Landing

    PubMed Central

    Huang, Yulin; Zha, Yuebo; Wang, Yue; Yang, Jianyu

    2015-01-01

    The forward looking radar imaging task is a practical and challenging problem for adverse weather aircraft landing industry. Deconvolution method can realize the forward looking imaging but it often leads to the noise amplification in the radar image. In this paper, a forward looking radar imaging based on deconvolution method is presented for adverse weather aircraft landing. We first present the theoretical background of forward looking radar imaging task and its application for aircraft landing. Then, we convert the forward looking radar imaging task into a corresponding deconvolution problem, which is solved in the framework of algebraic theory using truncated singular decomposition method. The key issue regarding the selecting of the truncated parameter is addressed using generalized cross validation approach. Simulation and experimental results demonstrate that the proposed method is effective in achieving angular resolution enhancement with suppressing the noise amplification in forward looking radar imaging. PMID:26094627

  19. Remote sensing of rainfall for debris-flow hazard assessment

    USGS Publications Warehouse

    Wieczorek, G.F.; Coe, J.A.; Godt, J.W.; ,

    2003-01-01

    Recent advances in remote sensing of rainfall provide more detailed temporal and spatial data on rainfall distribution. Four case studies of abundant debris flows over relatively small areas triggered during intense rainstorms are examined noting the potential for using remotely sensed rainfall data for landslide hazard analysis. Three examples with rainfall estimates from National Weather Service Doppler radar and one example with rainfall estimates from infrared imagery from a National Oceanic and Atmospheric Administration satellite are compared with ground-based measurements of rainfall and with landslide distribution. The advantages and limitations of using remote sensing of rainfall for landslide hazard analysis are discussed. ?? 2003 Millpress,.

  20. Meteorite Falls Observed in U.S. Weather Radar Data in 2015 and 2016 (To Date)

    NASA Technical Reports Server (NTRS)

    Fries, Marc; Fries, Jeffrey; Hankey, Mike; Matson, Robert

    2016-01-01

    To date, over twenty meteorite falls have been located in the weather radar imagery of the National Oceanic and Atmospheric Administration (NOAA)'s NEXRAD radar network. We present here the most prominent events recorded since the last Meteoritical Society meeting, covering most of 2015 and early 2016. Meteorite Falls: The following events produced evidence of falling meteorites in radar imagery and resulted in meteorites recovered at the fall site. Creston, CA (24 Oct 2015 0531 UTC): This event generated 218 eyewitness reports submitted to the American Meteor Society (AMS) and is recorded as event #2635 for 2015 on the AMS website. Witnesses reported a bright fireball with fragmentation terminating near the city of Creston, CA, north of Los Angeles. Sonic booms and electrophonic noise were reported in the vicinity of the event. Weather radar imagery records signatures consistent with falling meteorites in data from the KMUX, KVTX, KHNX and KVBX. The Meteoritical Society records the Creston fall as an L6 meteorite with a total recovered mass of 688g. Osceola, FL (24 Jan 2016 1527 UTC): This daytime fireball generated 134 eyewitness reports on AMS report number 266 for 2016, with one credible sonic boom report. The fireball traveled roughly NE to SW with a terminus location north of Lake City, FL in sparsely populated, forested countryside. Radar imagery shows distinct and prominent evidence of a significant meteorite fall with radar signatures seen in data from the KJAX and KVAX radars. Searchers at the fall site found that recoveries were restricted to road sites by the difficult terrain, and yet several meteorites were recovered. Evidence indicates that this was a relatively large meteorite fall where most of the meteorites are unrecoverable due to terrain. Osceola is an L6 meteorite with 991 g total mass recovered to date. Mount Blanco, TX (18 Feb 2016 0343 UTC): This event produced only 39 eyewitness reports and is recorded as AMS event #635 for 2016. No

  1. Identifying Precipitation Types Using Dual-Polarization-Based Radar and Numerical Weather Prediction Model Data

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The recent upgrade of dual-polarization with NEXRAD radars has assisted in improving the characterization of microphysical processes in precipitation and thus has enabled precipitation estimation based on the identified precipitation types. While this polarimetric capability promises the potential for the enhanced accuracy in quantitative precipitation estimation (QPE), recent studies show that the polarimetric estimates are still affected by uncertainties arising from the radar beam geometry/sampling space associated with the vertical variability of precipitation. The authors, first of all, focus on evaluating the NEXRAD hydrometeor classification product using ground reference data (e.g., ASOS) that provide simple categories of the observed precipitation types (e.g., rain, snow, and freezing rain). They also investigate classification uncertainty features caused by the variability of precipitation between the ground and the altitudes where radar samples. Since this variability is closely related to the atmospheric conditions (e.g., temperature) at near surface, useful information (e.g., critical thickness and temperature profile) that is not available in radar observations is retrieved from the numerical weather prediction (NWP) model data such as Rapid Refresh (RAP)/High Resolution Rapid Refresh (HRRR). The NWP retrieved information and polarimetric radar data are used together to improve the accuracy of precipitation type identification at near surface. The authors highlight major improvements and discuss limitations in the real-time application.

  2. A raingage, radar and satellite simulation study of the estimation of convective rainfall by area-time integrals

    NASA Technical Reports Server (NTRS)

    Short, David A.; Rosenfeld, Daniel; Wolff, David B.; Atlas, David

    1989-01-01

    Correlations between area-averaged rainrates and the areal fraction of rainrates exceeding a preset threshold, F(T), are examined using data from a network of 22 raingages located within 120 km of the NOAA/Tropical Ocean-Global Atmosphere (TOGA) C-band meteorological radar at Darwin, Australia. The results show that the area averages of convective rainfall are highly correlated with the fraction F(T). To simulate the use of the relationship between area-averaged rainrates and F(T) to obtain space-time averaged rainrates from a satellite sensor, observations from the NOAA/TOGA radar observations are used to estimate F(T) using a reflectivity threshold. The use of area-time integral methods for inferring area-averaged rainrates from satellites is examined, noting the possible use of the methodology for the Tropical Rainfall Measuring Mission.

  3. Effects of Uncertainty in TRMM Precipitation Radar Path Integrated Attenuation on Interannual Variations of Tropical Oceanic Rainfall

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Fitzjarrald, Dan E.; Kummerow, Christian D.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Considerable uncertainty surrounds the issue of whether precipitation over the tropical oceans (30 deg N/S) systematically changes with interannual sea-surface temperature (SST) anomalies that accompany El Nino (warm) and La Nina (cold) events. Time series of rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM Precipitation Radar (PR) over the tropical oceans show marked differences with estimates from two TRMM Microwave Imager (TMI) passive microwave algorithms. We show that path-integrated attenuation derived from the effects of precipitation on the radar return from the ocean surface exhibits interannual variability that agrees closely with the TMI time series. Further analysis of the frequency distribution of PR (2A25 product) rain rates suggests that the algorithm incorporates the attenuation measurement in a very conservative fashion so as to optimize the instantaneous rain rates. Such an optimization appears to come at the expense of monitoring interannual climate variability.

  4. Using NEXRAD Radar Rainfall to Calibrate a Development Impact Model in a Coastal Watershed

    NASA Astrophysics Data System (ADS)

    Sebastian, A.; Bedient, P.

    2012-12-01

    Low slopes and shallow, impermeable soils are characteristic of the Upper Texas Gulf Coast. These, coupled with large rainfall events, contribute to wide floodplains and ponding. Rapid, high intensity development has further exacerbated flooding in this coastal region. The Clear Creek Watershed is located in southeast Houston and empties into Galveston Bay. During the past decade, the watershed has been impacted by significant historical coastal storms and rainfall events such as Tropical Storm Allison (2001), Hurricane Ike (2008), and the April 2009 Event. In this study, we employ a calibrated, distributed hydrologic model and pre- and LID-development models to analyze how development characteristics have contributed to costly flooding in coastal watersheds. In 2012, Brody et al. used FEMA floodclaims collected over the 11-year period between 1999 and 2009 to examine the pattern of flood loss across the Clear Creek watershed. The results showed that the 100-year floodplain did not adequately represent overall or event-specific loss. Using a spatial cluster analysis, the Turkey Creek sub-area of the Clear Creek watershed was pin-pointed as an area of statistically significant flood loss, an area where there were a considerable number of high-value flood claims. This area is characterized by high-density, poorly constructed development and frequent flooding. In parallel with Brody's study of flood-risk indicators, our study aims to examine the behavior of the flood-wave in the coastal watershed and how it is affected by different development patterns. A distributed hydrologic VfloTM model was built for Turkey Creek using 2008 CCAP land cover data and calibrated using NEXRAD radar rainfall for the Hurricane Ike (2008) and April 2009 events. Once the model was calibrated, both pre- and LID-development models were built using historical land cover data. These models were used to identify how development patterns have influence the flood hydrograph. Early results

  5. Impact of coastal radar observability on the forecast of the track and rainfall of Typhoon Morakot (2009) using WRF-based ensemble Kalman filter data assimilation

    NASA Astrophysics Data System (ADS)

    Yue, Jian; Meng, Zhiyong; Yu, Cheng-Ku; Cheng, Lin-Wen

    2017-01-01

    This study explored the impact of coastal radar observability on the forecast of the track and rainfall of Typhoon Morakot (2009) using a WRF-based ensemble Kalman filter (EnKF) data assimilation (DA) system. The results showed that the performance of radar EnKF DA was quite sensitive to the number of radars being assimilated and the DA timing relative to the landfall of the tropical cyclone (TC). It was found that assimilating radial velocity (Vr) data from all the four operational radars during the 6 h immediately before TC landfall was quite important for the track and rainfall forecasts after the TC made landfall. The TC track forecast error could be decreased by about 43% and the 24-h rainfall forecast skill could be almost tripled. Assimilating Vr data from a single radar outperformed the experiment without DA, though with less improvement compared to the multiple-radar DA experiment. Different forecast performances were obtained by assimilating different radars, which was closely related to the first-time wind analysis increment, the location of moisture transport, the quasi-stationary rainband, and the local convergence line. However, only assimilating Vr data when the TC was farther away from making landfall might worsen TC track and rainfall forecasts. Besides, this work also demonstrated that Vr data from multiple radars, instead of a single radar, should be used for verification to obtain a more reliable assessment of the EnKF performance.

  6. Weak linkage between the heaviest rainfall and tallest storms

    PubMed Central

    Hamada, Atsushi; Takayabu, Yukari N.; Liu, Chuntao; Zipser, Edward J.

    2015-01-01

    Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. PMID:25708295

  7. The Python ARM Radar Toolkit (Py-ART), a library for working with weather radar data in the Python programming language

    SciTech Connect

    Helmus, Jonathan J.; Collis, Scott M.

    2016-07-18

    The Python ARM Radar Toolkit is a package for reading, visualizing, correcting and analysing data from weather radars. Development began to meet the needs of the Atmospheric Radiation Measurement Climate Research Facility and has since expanded to provide a general-purpose framework for working with data from weather radars in the Python programming language. The toolkit is built on top of libraries in the Scientific Python ecosystem including NumPy, SciPy, and matplotlib, and makes use of Cython for interfacing with existing radar libraries written in C and to speed up computationally demanding algorithms. As a result, the source code for the toolkit is available on GitHub and is distributed under a BSD license.

  8. The Python ARM Radar Toolkit (Py-ART), a library for working with weather radar data in the Python programming language

    DOE PAGES

    Helmus, Jonathan J.; Collis, Scott M.

    2016-07-18

    The Python ARM Radar Toolkit is a package for reading, visualizing, correcting and analysing data from weather radars. Development began to meet the needs of the Atmospheric Radiation Measurement Climate Research Facility and has since expanded to provide a general-purpose framework for working with data from weather radars in the Python programming language. The toolkit is built on top of libraries in the Scientific Python ecosystem including NumPy, SciPy, and matplotlib, and makes use of Cython for interfacing with existing radar libraries written in C and to speed up computationally demanding algorithms. As a result, the source code for themore » toolkit is available on GitHub and is distributed under a BSD license.« less

  9. Urban rainfall estimation employing commercial microwave links

    NASA Astrophysics Data System (ADS)

    Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko; ten Veldhuis, Marie-claire

    2015-04-01

    Urban areas often lack rainfall information. To increase the number of rainfall observations in cities, microwave links from operational cellular telecommunication networks may be employed. Although this new potential source of rainfall information has been shown to be promising, its quality needs to be demonstrated more extensively. In the Rain Sense kickstart project of the Amsterdam Institute for Advanced Metropolitan Solutions (AMS), sensors and citizens are preparing Amsterdam for future weather. Part of this project is rainfall estimation using new measurement techniques. Innovative sensing techniques will be utilized such as rainfall estimation from microwave links, umbrellas for weather sensing, low-cost sensors at lamp posts and in drainage pipes for water level observation. These will be combined with information provided by citizens in an active way through smartphone apps and in a passive way through social media posts (Twitter, Flickr etc.). Sensor information will be integrated, visualized and made accessible to citizens to help raise citizen awareness of urban water management challenges and promote resilience by providing information on how citizens can contribute in addressing these. Moreover, citizens and businesses can benefit from reliable weather information in planning their social and commercial activities. In the end city-wide high-resolution rainfall maps will be derived, blending rainfall information from microwave links and weather radars. This information will be used for urban water management. This presentation focuses on rainfall estimation from commercial microwave links. Received signal levels from tens of microwave links within the Amsterdam region (roughly 1 million inhabitants) in the Netherlands are utilized to estimate rainfall with high spatial and temporal resolution. Rainfall maps will be presented and compared to a gauge-adjusted radar rainfall data set. Rainfall time series from gauge(s), radars and links will be compared.

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

    NASA Astrophysics Data System (ADS)

    Martinez, Radame; Cranston, Robert; Porcello, John

    1995-01-01

    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.

  11. Turbulence as observed by concurrent measurements made at NSSL using weather radar, Doppler radar, Doppler lidar and aircraft

    NASA Technical Reports Server (NTRS)

    Lee, Jean T.

    1987-01-01

    As air traffic increases and aircraft capability increases in range and operating altitude, the exposure to weather hazards increases. Turbulence and wind shears are two of the most important of these hazards that must be taken into account if safe flight operations are to be accomplished. Beginning in the early 1960's, Project Rough Rider began thunderstorm investigations. Past and present efforts at the National Severe Storm Laboratory (NSSL) to measure these flight safety hazards and to describe the use of Doppler radar to detect and qualify these hazards are summarized. In particular, the evolution of the Doppler-measured radial velocity spectrum width and its applicability to the problem of safe flight is presented.

  12. Extraction of convective cloud parameters from Doppler Weather Radar MAX(Z) product using Image Processing Technique

    NASA Astrophysics Data System (ADS)

    Arunachalam, M. S.; Puli, Anil; Anuradha, B.

    2016-07-01

    In the present work continuous extraction of convective cloud optical information and reflectivity (MAX(Z) in dBZ) using online retrieval technique for time series data production from Doppler Weather Radar (DWR) located at Indian Meteorological Department, Chennai has been developed in MATLAB. Reflectivity measurements for different locations within the DWR range of 250 Km radii of circular disc area can be retrieved using this technique. It gives both time series reflectivity of point location and also Range Time Intensity (RTI) maps of reflectivity for the corresponding location. The Graphical User Interface (GUI) developed for the cloud reflectivity is user friendly; it also provides the convective cloud optical information such as cloud base height (CBH), cloud top height (CTH) and cloud optical depth (COD). This technique is also applicable for retrieving other DWR products such as Plan Position Indicator (Z, in dBZ), Plan Position Indicator (Z, in dBZ)-Close Range, Volume Velocity Processing (V, in knots), Plan Position Indicator (V, in m/s), Surface Rainfall Intensity (SRI, mm/hr), Precipitation Accumulation (PAC) 24 hrs at 0300UTC. Keywords: Reflectivity, cloud top height, cloud base, cloud optical depth

  13. Accuracy of rainfall measurement for scales of hydrological interest

    NASA Astrophysics Data System (ADS)

    Wood, S. J.; Jones, D. A.; Moore, R. J.

    The dense network of 49 raingauges over the 135 km2 Brue catchment in Somerset, England is used to examine the accuracy of rainfall estimates obtained from raingauges and from weather radar. Methods for data quality control and classification of precipitation types are first described. A super-dense network comprising eight gauges within a 2 km grid square is employed to obtain a "true value" of rainfall against which the 2 km radar grid and a single "typical gauge" estimate can be compared. Accuracy is assessed as a function of rainfall intensity, for different periods of time-integration (15 minutes, 1 hour and 1 day) and for two 8-gauge networks in areas of low and high relief. In a similar way, the catchment gauge network is used to provide the "true catchment rainfall" and the accuracy of a radar estimate (an area-weighted average of radar pixel values) and a single "typical gauge" estimate of catchment rainfall evaluated as a function of rainfall intensity. A single gauge gives a standard error of estimate for rainfall in a 2 km square and over the catchment of 33% and 65% respectively, at rain rates of 4 mm in 15 minutes. Radar data at 2 km resolution give corresponding errors of 50% and 55%. This illustrates the benefit of using radar when estimating catchment scale rainfall. A companion paper (Wood et al., 2000) considers the accuracy of rainfall estimates obtained using raingauge and radar in combination.

  14. A Method for Estimating Meteorite Fall Mass from Weather Radar Data

    NASA Technical Reports Server (NTRS)

    Laird, C.; Fries, M.; Matson, R.

    2017-01-01

    Techniques such as weather RADAR, seismometers, and all-sky cameras allow new insights concerning the physics of meteorite fall dynamics and fragmentation during "dark flight", the period of time between the end of the meteor's luminous flight and the concluding impact on the Earth's surface. Understanding dark flight dynamics enables us to rapidly analyze the characteristics of new meteorite falls. This analysis will provide essential information to meteorite hunters to optimize recovery, increasing the frequency and total mass of scientifically important freshly-fallen meteorites available to the scientific community. We have developed a mathematical method to estimate meteorite fall mass using reflectivity data as recorded by National Oceanic and Atmospheric Administration (NOAA) Next Generation RADAR (NEXRAD) stations. This study analyzed eleven official and one unofficial meteorite falls in the United States and Canada to achieve this purpose.

  15. Weather types across the Caribbean basin and their relationship with rainfall and sea surface temperature

    NASA Astrophysics Data System (ADS)

    Moron, Vincent; Gouirand, Isabelle; Taylor, Michael

    2016-07-01

    Eight weather types (WTs) are computed over 98.75°W-56.25°W, 8.75°N-31.25°N using cluster analysis of daily low-level (925 hPa) winds and outgoing longwave radiation, without removing the mean annual cycle, by a k-means algorithm from 1979 to 2013. The WTs can be firstly interpreted as snapshots of the annual cycle with a clear distinction between 5 "wintertime" and 3 "summertime" WTs, which account together for 70 % of the total mean annual rainfall across the studied domain. The wintertime WTs occur mostly from late November to late April and are characterized by varying intensity and location of the North Atlantic subtropical high (NASH) and transient synoptic troughs along the northern edge of the domain. Large-scale subsidence dominates the whole basin but rainfall can occur over sections of the basin, especially on the windward shores of the troughs associated with the synoptic waves. The transition between wintertime and summertime WTs is rather abrupt, especially in May. One summertime WT (WT 4) is prevalent in summer, and almost exclusive around late July. It is characterized by strong NASH, fast Caribbean low level jet and rainfall mostly concentrated over the Caribbean Islands, the Florida Peninsula, the whole Central America and the tropical Eastern Pacific. The two remaining summertime WTs display widespread rainfall respectively from Central America to Bermuda (WT 5) and over the Eastern Caribbean (WT 6). Both WTs combine reduced regional scale subsidence and weaker Caribbean low-level jet relatively to WT 4. The relationships between WT frequency and El Niño Southern Oscillation (ENSO) events are broadly linear. Warm central and eastern ENSO events are associated with more WT 4 (less WT 5-6) during boreal summer and autumn (0) while this relationship is reversed during boreal summer (+1) for central events only. In boreal winter, the largest anomalies are observed for two WTs consistent with negative (WT 2) and positive (WT 8) phases of the

  16. A radar-based regional extreme rainfall analysis to derive the thresholds for a novel automatic alert system in Switzerland

    NASA Astrophysics Data System (ADS)

    Panziera, Luca; Gabella, Marco; Zanini, Stefano; Hering, Alessandro; Germann, Urs; Berne, Alexis

    2016-06-01

    This paper presents a regional extreme rainfall analysis based on 10 years of radar data for the 159 regions adopted for official natural hazard warnings in Switzerland. Moreover, a nowcasting tool aimed at issuing heavy precipitation regional alerts is introduced. The two topics are closely related, since the extreme rainfall analysis provides the thresholds used by the nowcasting system for the alerts. Warm and cold seasons' monthly maxima of several statistical quantities describing regional rainfall are fitted to a generalized extreme value distribution in order to derive the precipitation amounts corresponding to sub-annual return periods for durations of 1, 3, 6, 12, 24 and 48 h. It is shown that regional return levels exhibit a large spatial variability in Switzerland, and that their spatial distribution strongly depends on the duration of the aggregation period: for accumulations of 3 h and shorter, the largest return levels are found over the northerly alpine slopes, whereas for longer durations the southern Alps exhibit the largest values. The inner alpine chain shows the lowest values, in agreement with previous rainfall climatologies. The nowcasting system presented here is aimed to issue heavy rainfall alerts for a large variety of end users, who are interested in different precipitation characteristics and regions, such as, for example, small urban areas, remote alpine catchments or administrative districts. The alerts are issued not only if the rainfall measured in the immediate past or forecast in the near future exceeds some predefined thresholds but also as soon as the sum of past and forecast precipitation is larger than threshold values. This precipitation total, in fact, has primary importance in applications for which antecedent rainfall is as important as predicted one, such as urban floods early warning systems. The rainfall fields, the statistical quantity representing regional rainfall and the frequency of alerts issued in case of

  17. Evaluation of X-band polarimetric radar estimation of rainfall and rain drop size distribution parameters in West Africa

    NASA Astrophysics Data System (ADS)

    Koffi, A. K.; Gosset, M.; Zahiri, E.-P.; Ochou, A. D.; Kacou, M.; Cazenave, F.; Assamoi, P.

    2014-06-01

    As part of the African Monsoon Multidisciplinary Analysis (AMMA) field campaign an X-band dual-polarization Doppler radar was deployed in Benin, West-Africa, in 2006 and 2007, together with a reinforced rain gauge network and several optical disdrometers. Based on this data set, a comparative study of several rainfall estimators that use X-band polarimetric radar data is presented. In tropical convective systems as encountered in Benin, microwave attenuation by rain is significant and quantitative precipitation estimation (QPE) at X-band is a challenge. Here, several algorithms based on the combined use of reflectivity, differential reflectivity and differential phase shift are evaluated against rain gauges and disdrometers. Four rainfall estimators were tested on twelve rainy events: the use of attenuation corrected reflectivity only (estimator R(ZH)), the use of the specific phase shift only R(KDP), the combination of specific phase shift and differential reflectivity R(KDP,ZDR) and an estimator that uses three radar parameters R(ZH,ZDR,KDP). The coefficients of the power law relationships between rain rate and radar variables were adjusted either based on disdrometer data and simulation, or on radar-gauges observations. The three polarimetric based algorithms with coefficients predetermined on observations outperform the R(ZH) estimator for rain rates above 10 mm/h which explain most of the rainfall in the studied region. For the highest rain rates (above 30 mm/h) R(KDP) shows even better scores, and given its performances and its simplicity of implementation, is recommended. The radar based retrieval of two parameters of the rain drop size distribution, the normalized intercept parameter NW and the volumetric median diameter Dm was evaluated on four rainy days thanks to disdrometers. The frequency distributions of the two parameters retrieved by the radar are very close to those observed with the disdrometer. NW retrieval based on a combination of ZH

  18. 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)

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

    2011-12-01

    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

  19. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.; Lee, Jonggil

    1991-01-01

    The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

  20. Cockpit weather radar display demonstrator and ground-to-air sferics telemetry system

    NASA Technical Reports Server (NTRS)

    Nickum, J. D.; Mccall, D. L.

    1982-01-01

    The results of two methods of obtaining timely and accurate severe weather presentations in the cockpit are detailed. The first method described is a course up display of uplinked weather radar data. This involves the construction of a demonstrator that will show the feasibility of producing a course up display in the cockpit of the NASA simulator at Langley. A set of software algorithms was designed that could easily be implemented, along with data tapes generated to provide the cockpit simulation. The second method described involves the uplinking of sferic data from a ground based 3M-Ryan Stormscope. The technique involves transfer of the data on the CRT of the Stormscope to a remote CRT. This sferic uplink and display could also be included in an implementation on the NASA cockpit simulator, allowing evaluation of pilot responses based on real Stormscope data.

  1. Prediction of a Flash Flood in Complex Terrain. Part II: A Comparison of Flood Discharge Simulations Using Rainfall Input from Radar, a Dynamic Model, and an Automated Algorithmic System.

    NASA Astrophysics Data System (ADS)

    Yates, David N.; Warner, Thomas T.; Leavesley, George H.

    2000-06-01

    Three techniques were employed for the estimation and prediction of precipitation from a thunderstorm that produced a flash flood in the Buffalo Creek watershed located in the mountainous Front Range near Denver, Colorado, on 12 July 1996. The techniques included 1) quantitative precipitation estimation using the National Weather Service's Weather Surveillance Radar-1988 Doppler and the National Center for Atmospheric Research's S-band, dual-polarization radars, 2) quantitative precipitation forecasting utilizing a dynamic model, and 3) quantitative precipitation forecasting using an automated algorithmic system for tracking thunderstorms. Rainfall data provided by these various techniques at short timescales (6 min) and at fine spatial resolutions (150 m to 2 km) served as input to a distributed-parameter hydrologic model for analysis of the flash flood. The quantitative precipitation estimates from the weather radar demonstrated their ability to aid in simulating a watershed's response to precipitation forcing from small-scale, convective weather in complex terrain. That is, with the radar-based quantitative precipitation estimates employed as input, the simulated peak discharge was similar to that estimated. The dynamic model showed the most promise in providing a significant forecast lead time for this flash-flood event. The algorithmic system did not show as much skill in comparison with the dynamic model in providing precipitation forcing to the hydrologic model. The discharge forecasts based on the dynamic-model and algorithmic-system inputs point to the need to improve the ability to forecast convective storms, especially if models such as these eventually are to be used in operational flood forecasting.

  2. Ranger© - An Affordable, Advanced, Next-Generation, Dual-Pol, X-Band Weather Radar

    NASA Astrophysics Data System (ADS)

    Stedronsky, Richard

    2014-05-01

    The Enterprise Electronics Corporation (EEC) Ranger© system is a new generation, X-band (3 cm), Adaptive Polarization Doppler Weather Surveillance Radar that fills the gap between high-cost, high-power traditional radar systems and the passive ground station weather sensors. Developed in partnership with the University of Oklahoma Advanced Radar Research Center (ARRC), the system uses relatively low power solid-state transmitters and pulse compression technology to attain nearly the same performance capabilities of much more expensive traditional radar systems. The Ranger© also employs Adaptive Dual Polarization (ADP) techniques to allow Alternating or Simultaneous Dual Polarization capability with total control over the transmission polarization state using dual independent coherent transmitters. Ranger© has been designed using the very latest technology available in the industry and the technical and manufacturing experience gained through over four decades of successful radar system design and production at EEC. The entire Ranger© design concept emphasizes precision, stability, reliability, and value using proven solid state technology combined with the most advanced motion control system ever conceived for weather radar. Key applications include meteorology, hydrology, aviation, offshore oil/gas drilling, wind energy, and outdoor event situational awareness.

  3. A Gaussian Random Field Approach for Merging Radar and Ground-Based Rainfall Data on Small Spatial and Temporal Scales

    NASA Astrophysics Data System (ADS)

    Krebsbach, K.; Friederichs, P.

    2014-12-01

    The generation of reliable precipitation products that explicitly account for spatial and temporal structures of precipitation events requires a combination of data with a variety of error structures and temporal resolutions. In-situ measurements are relatively accurate, but available only at sparse and irregularly distributed locations, whereas remote measurements cover areas but suffer from spatially and temporally inhomogeneous systematic errors. Besides gauge measurements are available on coarser spatial and temporal resolution in contrast to remote sensing measurements which are given on a fine spatial and temporal resolution. In our study we use precipitation rates from the composit of two X-band radars in Bonn and Jülich in Germany. Our aim is to formulate a statistical space-time model that aggregates and disaggregates precipitation rates from radar and gauge observations. We model a Gaussian random field as underlying process, where we face the task of dealing with a large non-Gaussian data set. To start the analysis of the unadjusted radar rainfall rates, we follow the work of D. Allcroft and C. Glasbey (2003) and transform the data to a truncated Gaussian distribution. The advantage of the latent variable approach is that it takes account of the occurence of rainfall and the intensity using a single process. We proceed by estimating the empirical correlation from these transformed values with maximum likelihood methods and fit a parametric correlation function that gives rise to a Gaussian random field. Since the transformation gives censored values to dry locations, we simulate values for this area that lie below some threshold and extend the Gaussian field to the whole domain. In order to merge gauge and radar data for precipitation, we first aggregate the data to a scale on which the comparison is reasonable and then disaggregate again back to smaller desirable scales. The disaggregation step consists of calculating the difference between radar

  4. Visualization and Nowcasting for Aviation using online verified ensemble weather radar extrapolation.

    NASA Astrophysics Data System (ADS)

    Kaltenboeck, Rudolf; Kerschbaum, Markus; Hennermann, Karin; Mayer, Stefan

    2013-04-01

    Nowcasting of precipitation events, especially thunderstorm events or winter storms, has high impact on flight safety and efficiency for air traffic management. Future strategic planning by air traffic control will result in circumnavigation of potential hazardous areas, reduction of load around efficiency hot spots by offering alternatives, increase of handling capacity, anticipation of avoidance manoeuvres and increase of awareness before dangerous areas are entered by aircraft. To facilitate this rapid update forecasts of location, intensity, size, movement and development of local storms are necessary. Weather radar data deliver precipitation analysis of high temporal and spatial resolution close to real time by using clever scanning strategies. These data are the basis to generate rapid update forecasts in a time frame up to 2 hours and more for applications in aviation meteorological service provision, such as optimizing safety and economic impact in the context of sub-scale phenomena. On the basis of tracking radar echoes by correlation the movement vectors of successive weather radar images are calculated. For every new successive radar image a set of ensemble precipitation fields is collected by using different parameter sets like pattern match size, different time steps, filter methods and an implementation of history of tracking vectors and plausibility checks. This method considers the uncertainty in rain field displacement and different scales in time and space. By validating manually a set of case studies, the best verification method and skill score is defined and implemented into an online-verification scheme which calculates the optimized forecasts for different time steps and different areas by using different extrapolation ensemble members. To get information about the quality and reliability of the extrapolation process additional information of data quality (e.g. shielding in Alpine areas) is extrapolated and combined with an extrapolation

  5. A grid-based distributed flood forecasting model for use with weather radar data: Part 1. Formulation

    NASA Astrophysics Data System (ADS)

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

    A practical methodology for distributed rainfall-runoff modelling using grid square weather radar data is developed for use in real-time flood forecasting. The model, called the Grid Model, is configured so as to share the same grid as used by the weather radar, thereby exploiting the distributed rainfall estimates to the full. Each grid square in the catchment is conceptualised as a storage which receives water as precipitation and generates water by overflow and drainage. This water is routed across the catchment using isochrone pathways. These are derived from a digital terrain model assuming two fixed velocities of travel for land and river pathways which are regarded as model parameters to be optimised. Translation of water between isochrones is achieved using a discrete kinematic routing procedure, parameterised through a single dimensionless wave speed parameter, which advects the water and incorporates diffusion effects through the discrete space-time formulation. The basic model routes overflow and drainage separately through a parallel system of kinematic routing reaches, characterised by different wave speeds but using the same isochrone-based space discretisation; these represent fast and slow pathways to the basin outlet, respectively. A variant allows the slow pathway to have separate isochrones calculated using Darcy velocities controlled by the hydraulic gradient as estimated by the local gradient of the terrain. Runoff production within a grid square is controlled by its absorption capacity which is parameterised through a simple linkage function to the mean gradient in the square, as calculated from digital terrain data. This allows absorption capacity to be specified differently for every grid square in the catchment through the use of only two regional parameters and a DTM measurement of mean gradient for each square. An extension of this basic idea to consider the distribution of gradient within the square leads analytically to a Pareto

  6. Validation of satellite OPEMW precipitation product with ground-based weather radar and rain gauge networks

    NASA Astrophysics Data System (ADS)

    Cimini, D.; Romano, F.; Ricciardelli, E.; Di Paola, F.; Viggiano, M.; Marzano, F. S.; Colaiuda, V.; Picciotti, E.; Vulpiani, G.; Cuomo, V.

    2013-11-01

    The Precipitation Estimation at Microwave Frequencies (PEMW) algorithm was developed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy (IMAA-CNR) for inferring surface rain intensity (sri) from satellite passive microwave observations in the range from 89 to 190 GHz. The operational version of PEMW (OPEMW) has been running continuously at IMAA-CNR for two years. The OPEMW sri estimates, together with other precipitation products, are used as input to an operational hydrological model for flood alert forecast. This paper presents the validation of OPEMW against simultaneous ground-based observations from a network of 20 weather radar systems and a network of more than 3000 rain gauges distributed over the Italian Peninsula and main islands. The validation effort uses a data set covering one year (July 2011-June 2012). The effort evaluates dichotomous and continuous scores for the assessment of rain detection and quantitative estimate, respectively, investigating both spatial and temporal features. The analysis demonstrates 98% accuracy in correctly identifying rainy and non-rainy areas; it also quantifies the increased ability (with respect to random chance) to detect rainy and non-rainy areas (0.42-0.45 Heidke skill score) or rainy areas only (0.27-0.29 equitable threat score). Performances are better than average during summer, fall, and spring, while worse than average in the winter season. The spatial-temporal analysis does not show seasonal dependence except over the Alps and northern Apennines during winter. A binned analysis in the 0-15 mm h-1 range suggests that OPEMW tends to slightly overestimate sri values below 6-7 mm h-1 and underestimate sri above those values. With respect to rain gauges (weather radars), the correlation coefficient is larger than 0.8 (0.9). The monthly mean difference and standard deviation remain within ±1 and 2 mm h-1 with respect to rain gauges (respectively -2-0 and 4 mm h-1

  7. Validation of satellite OPEMW precipitation product with ground-based weather radar and rain gauge networks

    NASA Astrophysics Data System (ADS)

    Cimini, D.; Romano, F.; Ricciardelli, E.; Di Paola, F.; Viggiano, M.; Marzano, F. S.; Colaiuda, V.; Picciotti, E.; Vulpiani, G.; Cuomo, V.

    2013-05-01

    The Precipitation Estimation at Microwave Frequencies (PEMW) algorithm was developed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy (IMAA-CNR) for inferring surface rain intensity (sri) from satellite passive microwave observations in the range from 89 to 190 GHz. The operational version of PEMW (OPEMW) has been running continuously at IMAA-CNR for two years, producing sri estimates feeding an operational hydrological model for forecasting flood alerts. This paper presents the validation of OPEMW against simultaneous ground-based observations obtained by a network of 20 weather radars and a network of more than 3000 rain gauges distributed over the Italian peninsula and main islands. The validation effort uses a data set spanning a one-year period (July 2011-June 2012). The effort evaluates dichotomous and continuous scores for the assessment of rain detection and quantitative estimate, respectively, investigating both spatial and temporal features. The analysis demonstrates 98% accuracy in correctly identifying rainy and non-rainy areas, and it quantifies the increased ability (with respect to random chance) to detect rainy and non-rainy areas (0.42-0.45 Heidke skill score) or rainy areas only (0.27-0.29 equitable threat score). Performances are better than average during summer, fall, and spring, while worse than average in the winter season. The spatial-temporal analysis does not show seasonal dependence except for larger mean absolute difference over the Alps and northern Apennines during winter, attributable to residual effect of snow cover. A binned analysis in the 0-15 mm h-1 range suggests that OPEMW tends to slightly overestimate sri values below 6-7 mm h-1, and to underestimate sri above those values. Depending upon the ground reference (either rain gauges or weather radars), the mean difference is 0.8-2.8 mm h-1, with a standard deviation within 2.6-3.1 mm h-1 and correlation coefficient within 0

  8. The evaluation of satellite-borne weather radar system designs using real ground-based radar data

    NASA Technical Reports Server (NTRS)

    Dobson, E. B.; Kalshoven, J. E., Jr.

    1977-01-01

    The paper presents method of evaluating proposed satellite radar systems using real radar data, and discusses methods of displaying the results which will hopefully facilitate easy comparison of systems. A single pencil beam pulsed radar system is considered while the precipitation data base comes from six rain days observed by SPANDAR. The many additional factors that must be considered in the radar equation such as attenuation and scattering (Mie and Rayleigh) are discussed along with some indication where possible errors lie.

  9. Assimilation of microwave, infrared, and radio occultation satellite observations with a weather research and forecasting model for heavy rainfall forecasting

    NASA Astrophysics Data System (ADS)

    Boonyuen, Pakornpop; Wu, Falin; Phunthirawuth, Parwapath; Zhao, Yan

    2016-10-01

    In this research, satellite observation data were assimilated into Weather Research and Forecasting Model (WRF) by using Three-dimensional Variational Data Assimilation System (3DVAR) to analyze its impacts on heavy rainfall forecasts. The weather case for this research was during 13-18 September 2015. Tropical cyclone VAMCO, forming in South China Sea near with Vietnam, moved on west direction to the Northeast of Thailand. After passed through Vietnam, the tropical cyclone was become to depression and there was heavy rainfall throughout the area of Thailand. Observation data, used in this research, included microwave radiance observations from the Advanced Microwave Sounding Unit-A (AMSU-A), infrared radiance observations from Infrared Atmospheric Sounding Interferometer (IASI), and GPS radio occultation (RO) from the COSMIC and CHAMP missions. The experiments were designed in five cases, namely, 1) without data assimilation (CTRL); 2) with only RO data (RO); 3) with only AMSU-A data (AMSUA); 4) with only IASI data (IASI); and 5) with all of RO, AMSU-A and IASI data assimilation (ALL). Then all experiment results would be compared with both NCEP FNL (Final) Operational Global Analysis and the observation data from Thai Meteorological Department weather stations. The experiments result demonstrated that with microwave (AMSU-A), infrared (IASI) and GPS radio occultation (RO) data assimilation can produce the positive impact on analyses and forecast. All of satellite data assimilations have corresponding positive effects in term of temperature and humidity forecasting, and the GPS-RO assimilation produces the best of temperature and humidity forecast biases. The satellite data assimilation has a good impact on temperature and humidity in lower troposphere and vertical distribution that very helpful for heavy rainfall forecast improvement.

  10. A characterization of autumn nocturnal migration detected by weather surveillance radars in the northeastern USA.

    PubMed

    Farnsworth, Andrew; Van DOREN, Benjamin M; Hochachka, Wesley M; Sheldon, Daniel; Winner, Kevin; Irvine, Jed; Geevarghese, Jeffrey; Kelling, Steve

    2016-04-01

    Billions of birds migrate at night over North America each year. However, few studies have described the phenology of these movements, such as magnitudes, directions, and speeds, for more than one migration season and at regional scales. In this study, we characterize density, direction, and speed of nocturnally migrating birds using data from 13 weather surveillance radars in the autumns of 2010 and 2011 in the northeastern USA. After screening radar data to remove precipitation, we applied a recently developed algorithm for characterizing velocity profiles with previously developed methods to document bird migration. Many hourly radar scans contained windborne "contamination," and these scans also exhibited generally low overall reflectivities. Hourly scans dominated by birds showed nightly and seasonal patterns that differed markedly from those of low reflectivity scans. Bird migration occurred during many nights, but a smaller number of nights with large movements of birds defined regional nocturnal migration. Densities varied by date, time, and location but peaked in the second and third deciles of night during the autumn period when the most birds were migrating. Migration track (the direction to which birds moved) shifted within nights from south-southwesterly to southwesterly during the seasonal migration peaks; this shift was not consistent with a similar shift in wind direction. Migration speeds varied within nights, although not closely with wind speed. Airspeeds increased during the night; groundspeeds were highest between the second and third deciles of night, when the greatest density of birds was migrating. Airspeeds and groundspeeds increased during the fall season, although groundspeeds fluctuated considerably with prevailing winds. Significant positive correlations characterized relationships among bird densities at southern coastal radar stations and northern inland radar stations. The quantitative descriptions of broadscale nocturnal migration

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  12. Rainfall estimates for hydrological models: Comparing rain gauge, radar and microwave link data as input for the Wageningen Lowland Runoff Simulator (WALRUS)

    NASA Astrophysics Data System (ADS)

    Brauer, Claudia; Overeem, Aart; Uijlenhoet, Remko

    2015-04-01

    Several rainfall measurement techniques are available for hydrological applications, each with its own spatial and temporal resolution. We investigated the effect of differences in rainfall estimates on discharge simulations in a lowland catchment by forcing a novel rainfall-runoff model (WALRUS) with rainfall data from gauges, radars and microwave links. The hydrological model used for this analysis is the recently developed Wageningen Lowland Runoff Simulator (WALRUS). WALRUS is a rainfall-runoff model accounting for hydrological processes relevant to areas with shallow groundwater (e.g. groundwater-surface water feedback). Here, we used WALRUS for case studies in the Hupsel Brook catchment. We used two automatic rain gauges with hourly resolution, located inside the catchment (the base run) and 30 km northeast. Operational (real-time) and climatological (gauge-adjusted) C-band radar products and country-wide rainfall maps derived from microwave link data from a cellular telecommunication network were also used. Discharges simulated with these different inputs were compared to observations. Traditionally, the precipitation research community places emphasis on quantifying spatial errors and uncertainty, but for hydrological applications, temporal errors and uncertainty should be quantified as well. Its memory makes the hydrologic system sensitive to missed or badly timed rainfall events, but also emphasizes the effect of a bias in rainfall estimates. Systematic underestimation of rainfall by the uncorrected operational radar product leads to very dry model states and an increasing underestimation of discharge. Using the rain gauge 30 km northeast of the catchment yields good results for climatological studies, but not for forecasting individual floods. Simulating discharge using the maps derived from microwave link data and the gauge-adjusted radar product yields good results for both events and climatological studies. This indicates that these products can be

  13. HF Radar Observations of Space Weather Effects in the Low and Mid-latitude Ionosphere

    NASA Astrophysics Data System (ADS)

    Menk, F. W.

    2015-12-01

    The ionosphere is dynamically coupled to the magnetosphere and hence diurnal and seasonal processes in the ionosphere are strongly influenced by space weather effects. These may vary the electron density distribution and cause changes in the reflection and absorption of HF radio signals. Other consequences include the formation of enhanced convective flows and irregularity features which may contribute to Doppler clutter. While there has been much discussion on the ionospheric signatures of magnetic storms at high latitudes, this presentation focuses on effects detected using mid- and low-latitude HF radars which examine field lines mapping to the vicinity of the ring current. Characteristic features include travelling ionospheric disturbances, high velocity flows and sustained irregular and quasi-sinusoidal 5 - 20 mHz waves recorded near the plasmapause. Such observations provide new insight on complex M-I coupling dynamics.

  14. Diagnostics of Rainfall Anomalies in the Nordeste During the Global Weather Experiment

    NASA Technical Reports Server (NTRS)

    Sikdar, D. M.

    1984-01-01

    The relationship of the daily variability of large-scale pressure, cloudiness and upper level wind patterns over the Brazil-Atlantic sector during March/April 1979 to rainfall anomalies in northern Nordeste was investigated. The experiment divides the rainy season (March/April) of 1979 into wet and dry days, then composites bright cloudiness, sea level pressure, and upper level wind fields with respect to persistent rainfall episodes. Wet and dry anomalies are analyzed along with seasonal mean conditions.

  15. The New Weather Radar for America's Space Program in Florida: A Temperature Profile Adaptive Scan Strategy

    NASA Technical Reports Server (NTRS)

    Carey, L. D.; Petersen, W. A.; Deierling, W.; Roeder, W. P.

    2009-01-01

    A new weather radar is being acquired for use in support of America s space program at Cape Canaveral Air Force Station, NASA Kennedy Space Center, and Patrick AFB on the east coast of central Florida. This new radar replaces the modified WSR-74C at Patrick AFB that has been in use since 1984. The new radar is a Radtec TDR 43-250, which has Doppler and dual polarization capability. A new fixed scan strategy was designed to best support the space program. The fixed scan strategy represents a complex compromise between many competing factors and relies on climatological heights of various temperatures that are important for improved lightning forecasting and evaluation of Lightning Launch Commit Criteria (LCC), which are the weather rules to avoid lightning strikes to in-flight rockets. The 0 C to -20 C layer is vital since most generation of electric charge occurs within it and so it is critical in evaluating Lightning LCC and in forecasting lightning. These are two of the most important duties of 45 WS. While the fixed scan strategy that covers most of the climatological variation of the 0 C to -20 C levels with high resolution ensures that these critical temperatures are well covered most of the time, it also means that on any particular day the radar is spending precious time scanning at angles covering less important heights. The goal of this project is to develop a user-friendly, Interactive Data Language (IDL) computer program that will automatically generate optimized radar scan strategies that adapt to user input of the temperature profile and other important parameters. By using only the required scan angles output by the temperature profile adaptive scan strategy program, faster update times for volume scans and/or collection of more samples per gate for better data quality is possible, while maintaining high resolution at the critical temperature levels. The temperature profile adaptive technique will also take into account earth curvature and refraction

  16. Assessment of bird response to the Migratory Bird Habitat Initiative using weather-surveillance radar

    USGS Publications Warehouse

    Sieges, Mason L.; Smolinsky, Jaclyn A.; Baldwin, Michael J.; Barrow, Wylie C.; Randall, Lori A.; Buler, Jeffrey J.

    2014-01-01

    In response to the Deepwater Horizon oil spill in spring 2010, the Natural Resources Conservation Service implemented the Migratory Bird Habitat Initiative (MBHI) to provide temporary wetland habitat for migrating and wintering waterfowl, shorebirds, and other birds along the northern Gulf of Mexico via managed flooding of agricultural lands. We used weather-surveillance radar to conduct broad regional assessments of bird response to MBHI activities within the Mississippi Alluvial Valley and the West Gulf Coastal Plain. Across both regions, birds responded positively to MBHI management by exhibiting greater relative bird densities within sites relative to pre-management conditions in prior years and relative to surrounding non-flooded agricultural lands. Bird density at MBHI sites was generally greatest during winter for both regions. Unusually high flooding in the years prior to implementation of the MBHI confounded detection of overall changes in remotely sensed soil wetness across sites. The magnitude of bird response at MBHI sites compared to prior years and to non-flooded agricultural lands was generally related to the surrounding landscape context: proximity to areas of high bird density, amount of forested wetlands, emergent marsh, non-flooded agriculture, or permanent open water. However, these relationships varied in strength and direction between regions and seasons, a finding which we attribute to differences in seasonal bird composition and broad regional differences in landscape configuration and composition. We detected greater increases in relative bird use at sites in closer proximity to areas of high bird density during winter in both regions. Additionally, bird density was greater during winter at sites with more emergent marsh in the surrounding landscape. Thus, bird use of managed wetlands could be maximized by enrolling lands located near areas of known bird concentration and within a mosaic of existing wetlands. Weather-radar observations

  17. Weather radar data correlate to hail-induced mortality in grassland birds

    USGS Publications Warehouse

    Carver, Amber; Ross, Jeremy D.; Augustine, David J.; Skagen, Susan K.; Dwyer, Angela M.; Tomback, Diana F.; Wunder, Michael B.

    2017-01-01

    Small-bodied terrestrial animals such as songbirds (Order Passeriformes) are especially vulnerable to hail-induced mortality; yet, hail events are challenging to predict, and they often occur in locations where populations are not being studied. Focusing on nesting grassland songbirds, we demonstrate a novel approach to estimate hail-induced mortality. We quantify the relationship between the probability of nests destroyed by hail and measured Level-III Next Generation Radar (NEXRAD) data, including atmospheric base reflectivity, maximum estimated size of hail and maximum estimated azimuthal wind shear. On 22 June 2014, a hailstorm in northern Colorado destroyed 102 out of 203 known nests within our research site. Lark bunting (Calamospiza melanocorys) nests comprised most of the sample (n = 186). Destroyed nests were more likely to be found in areas of higher storm intensity, and distributions of NEXRAD variables differed between failed and surviving nests. For 133 ground nests where nest-site vegetation was measured, we examined the ameliorative influence of woody vegetation, nest cover and vegetation density by comparing results for 13 different logistic regression models incorporating the independent and additive effects of weather and vegetation variables. The most parsimonious model used only the interactive effect of hail size and wind shear to predict the probability of nest survival, and the data provided no support for any of the models without this predictor. We conclude that vegetation structure may not mitigate mortality from severe hailstorms and that weather radar products can be used remotely to estimate potential for hail mortality of nesting grassland birds. These insights will improve the efficacy of grassland bird population models under predicted climate change scenarios.

  18. Variability of extreme weather events over the equatorial East Africa, a case study of rainfall in Kenya and Uganda

    NASA Astrophysics Data System (ADS)

    Ongoma, Victor; Chen, Haishan; Omony, George William

    2016-10-01

    This study investigates the variability of extreme rainfall events over East Africa (EA), using indices from the World Meteorological Organization (WMO) Expert Team on Climate Change Detection and Indices (ETCCDI). The analysis was based on observed daily rainfall from 23 weather stations, with length varying within 1961 and 2010. The indices considered are: wet days (R ≥1 mm), annual total precipitation in wet days (PRCPTOT), simple daily intensity index (SDII), heavy precipitation days (R ≥ 10 mm), very heavy precipitation days (R ≥ 20 mm), and severe precipitation (R ≥ 50 mm). The non-parametric Mann-Kendall statistical analysis was carried out to identify trends in the data. Temporal precipitation distribution was different from station to station. Almost all indices considered are decreasing with time. The analysis shows that the PRCPTOT, very heavy precipitation, and severe precipitation are generally declining insignificantly at 5 % significant level. The PRCPTOT is evidently decreasing over Arid and Semi-Arid Land (ASAL) as compared to other parts of EA. The number of days that recorded heavy rainfall is generally decreasing but starts to rise in the last decade although the changes are insignificant. Both PRCPTOT and heavy precipitation show a recovery in trend starting in the 1990s. The SDII shows a reduction in most areas, especially the in ASAL. The changes give a possible indication of the ongoing climate variability and change which modify the rainfall regime of EA. The results form a basis for further research, utilizing longer datasets over the entire region to reduce the generalizations made herein. Continuous monitoring of extreme events in EA is critical, given that rainfall is projected to increase in the twenty-first century.

  19. Stability of the U.S. weather radar network and its implications for TRMM and GPM ground validation

    NASA Astrophysics Data System (ADS)

    Morris, K. R.; Schwaller, M.; Marks, D. A.; Wolff, D. B.; Petersen, W. A.; Pippitt, J. L.

    2013-12-01

    Ground validation of rainfall and reflectivity measurements from the Precipitation Radar (PR) on the Tropical Rainfall Measuring Mission (TRMM) satellite has relied on comparisons to measurements from ground radars (GR), in particular to those from the WSR-88D radar network over the U.S. In support of TRMM PR validation and in preparation for validation of the Dual-frequency Precipitation Radar for the upcoming Global Precipitation Measurement (GPM) mission, NASA established a Validation Network (VN) of 21 WSR-88D sites in the southeastern U.S. Quality-controlled data from these sites have been used to perform reflectivity and rain rate comparisons to TRMM PR continually since mid-2006. VN data were used to assess the stability and calibration accuracy of the WSR-88D radars. The PR-GR reflectivity and rain rate comparisons are based on a technique of 3-D volume and resolution matching between the two radar observation systems, where each matching volume is characterized by location, rain type, proximity to the bright band, and quality of the matchup in terms of beam filling and uniformity. Calibration differences between PR and GR are evaluated by inspecting stratiform rain samples above the bright band, where PR attenuation and reflectivity gradient effects are minimal. Time series of GR-PR mean reflectivity differences reveal site-specific trends in GR calibration, under the assumption that the PR calibration is stable and well known. Recent changes in the baseline calibration differences between PR and GR have occurred coincident with upgrades to dual-polarization capability at several VN WSR-88D sites. Overall, 16 of the 21 WSR-88D radars in the GPM Validation Network were found to be running measurably 'cooler' following the dual polarization upgrade, when compared to TRMM PR. These changes are evident in the long-term trend of PR-GR reflectivity comparisons, and in specific examples of short-term anomalies in WSR 88D calibration. Additional, independent

  20. Retrieval algorithm for rainfall mapping from microwave links in a cellular communication network

    NASA Astrophysics Data System (ADS)

    Overeem, Aart; Uijlenhoet, Remko; Leijnse, Hidde

    2016-04-01

    Microwave links in commercial cellular communication networks hold a promise for areal rainfall monitoring and could complement rainfall estimates from ground-based weather radars, rain gauges, and satellites. It has been shown that country-wide rainfall maps can be derived from the signal attenuations of microwave links in such a network. We present a rainfall retrieval algorithm, which is employed to obtain rainfall maps from microwave links in a cellular communication network. We compare these rainfall maps to gauge-adjusted radar rainfall maps. The microwave link data set, as well as the developed code, a package in the open source scripting language "R", are freely available at GitHub (https://github.com/overeem11/RAINLINK). The purpose of this presentation is to promote rainfall mapping utilizing microwave links from cellular communication networks as an alternative or complementary means for continental-scale rainfall monitoring.

  1. Lithological and textural controls on radar and diurnal thermal signatures of weathered volcanic deposits, Lunar Crater region, Nevada

    NASA Technical Reports Server (NTRS)

    Plaut, Jeffrey J.; Rivard, Benoit

    1992-01-01

    Radar backscatter intensity as measured by calibrated synthetic aperture radar (SAR) systems is primarily controlled by three factors: local incidence angle, wavelength-scale roughness, and dielectric permittivity of surface materials. Radar observations may be of limited use for geological investigations of surface composition, unless the relationships between lithology and the above characteristics can be adequately understood. In arid terrains, such as the Southwest U.S., weathering signatures (e.g. soil development, fracturing, debris grain size and shape, and hill slope characteristics) are controlled to some extent by lithologic characteristics of the parent bedrock. These textural features of outcrops and their associated debris will affect radar backscatter to varying degrees, and the multiple-wavelength capability of the JPL Airborne SAR (AIRSAR) system allows sampling of textures at three distinct scales. Diurnal temperature excursions of geologic surfaces are controlled primarily by the thermal inertia of surface materials, which is a measure of the resistance of a material to a change in temperature. Other influences include albedo, surface slopes affecting insolation, local meteorological conditions and surface emissivity at the relevant thermal wavelengths. To first order, thermal inertia variations on arid terrain surfaces result from grain size distribution and porosity differences, at scales ranging from micrometers to tens of meters. Diurnal thermal emission observations, such as those made by the JPL Thermal Infrared Multispectral Scanner (TIMS) airborne instrument, are thus influenced by geometric surface characteristics at scales comparable to those controlling radar backscatter. A preliminary report on a project involving a combination of field, laboratory and remote sensing observations of weathered felsic-to basaltic volcanic rock units exposed in the southern part of the Lunar Crater Volcanic Field, in the Pancake Range of central Nevada is

  2. Tropical convective systems life cycle characteristics from geostationary satellite and precipitating estimates derived from TRMM and ground weather radar observations for the West African and South American regions

    NASA Astrophysics Data System (ADS)

    Fiolleau, T.; Roca, R.; Angelis, F. C.; Viltard, N.

    2012-12-01

    In the tropics most of the rainfall comes in the form of individual storm events embedded in the synoptic circulations (e.g., monsoons). Understanding the rainfall and its variability hence requires to document these highly contributing tropical convective systems (MCS). Our knowledge of the MCS life cycle, from a physical point of view mainly arises from individual observational campaigns heavily based on ground radar observations. While this large part of observations enabled the creation of conceptual models of MCS life cycle, it nevertheless does not reach any statistically significant integrated perspective yet. To overcome this limitation, a composite technique, that will serve as a Day-1 algorithm for the Megha-Tropiques mission, is considered in this study. this method is based on a collocation in space and time of the level-2 rainfall estimates (BRAIN) derived from the TMI radiometer onboard TRMM with the cloud systems identified by a new MCS tracking algorithm called TOOCAN and based on a 3-dimensional segmentation (image + time) of the geostationary IR imagery. To complete this study, a similar method is also developed collocating the cloud systems with the precipitating features derived from the ground weather radar which has been deployed during the CHUVA campaign over several Brazilian regions from 2010 up to now. A comparison of the MCSs life cycle is then performed for the 2010-2012 summer seasons over the West African, and South American regions. On the whole region of study, the results show that the temporal evolution of the cold cloud shield associated to MCSs describes a symmetry between the growth and the decay phases. It is also shown that the parameters of the conceptual model of MCSs are strongly correlated, reducing thereby the problem to a single degree of freedom. At the system scale, over both land and oceanic regions, rainfall is described by an increase at the beginning (the first third) of the life cycle and then smoothly decreases

  3. 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...

  4. 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...

  5. The very short-term rainfall forecasting for a mountainous watershed by means of an ensemble numerical weather prediction system in Taiwan

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chang; Lin, Gwo-Fong

    2017-03-01

    During typhoons, accurate forecasts of rainfall are always desired for various kinds of disaster warning systems to reduce the impact of rainfall-induced disasters. However, rainfall forecasting, especially the very short-term (hourly) rainfall, is one of the most difficult tasks in hydrology due to the high variability in space and time and the complex physical process. In this study, the purpose is to provide effective forecasts of very short-term rainfall by means of the ensemble numerical weather prediction system in Taiwan. To this end, the ensemble forecasts of hourly rainfall from this ensemble numerical weather prediction system are analyzed to evaluate the performance. Furthermore, a methodology, which is based on the principle of analogue prediction, is proposed to effectively process these ensemble forecasts for improving the performance on very short-term rainfall forecasting. To clearly demonstrate the advantage of the proposed methodology, actual application is conducted on a mountainous watershed to yield 1- to 6-h ahead forecasts during typhoon events. The results indicate that the proposed methodology is better performed and more flexible than the conventional one. Generally, the proposed methodology provides improved performance for very short-term rainfall forecasting, especially for 1- to 2-h ahead forecasting. The improved forecasts provided by the proposed methodology are expected to be useful to support disaster warning systems, such as flash-flood, landslide, and debris flow warning systems, during typhoons.

  6. Remote rainfall sensing for landslide hazard analysis

    USGS Publications Warehouse

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

    2001-01-01

    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.

  7. Combined Radar-Radiometer Rainfall Retrieval for TRMM Using Structure Function-Based Optimization

    DTIC Science & Technology

    2011-07-28

    Cumulonimbus vertical velocity events in GATE. Part II: Synthesis and model core structure. J. Appi . Meteor., 37, 2458-2469. 187 BIOGRAPHICAL SKETCH...rainfall retrieval algorithms,. J. Appi . Meteor., 33, 313-333. Farrar, M.R., and E.A. Smith, 1992: Spatial resolution enhancement of terrestrial features

  8. Ground-based microwave weather radar observations and retrievals during the 2014 Holuhraun eruption (Bárðarbunga, Iceland)

    NASA Astrophysics Data System (ADS)

    Mereu, Luigi; Silvio Marzano, Frank; Barsotti, Sara; Montopoli, Mario; Yeo, Richard; Arngrimsson, Hermann; Björnsson, Halldór; Bonadonna, Costanza

    2015-04-01

    During an eruptive event the real-time forecasting of ash dispersal into the atmosphere is a key factor to prevent air traffic disasters. The ash plume is extremely hazardous to aircraft that inadvertently may fly through it. Real-time monitoring of such phenomena is crucial, particularly to obtain specific data for the initialization of eruption and dispersion models in terms of source parameters. The latter, such as plume height, ash concentration, mass flow rate and size spectra, are usually very difficult to measure or to estimate with a relatively good accuracy. Over the last years different techniques have been developed to improved ash plume detection and retrieval. Satellite-based observations, using multi-frequency visible and infrared radiometers, are usually exploited for monitoring and measuring dispersed ash clouds. The observations from geostationary orbit suffer from a relatively poor spatial resolution, whereas the low orbit level has a relatively poor temporal resolution. Moreover, the field-of-view of infrared radiometric measurements may be reduced by obstructions caused by water and ice clouds lying between the ground and the sensor's antenna. Weather radar-based observations represent an emerging technique to detect and, to a certain extent, mitigate the hazard from the ash plumes. Ground-based microwave scanning radar systems can provide the three-dimensional information about the detected ash volume with a fairly high spatial resolution every few minutes and in all weather conditions. Methodological studies have recently investigated the possibility of using single-polarization and dual-polarization ground-based radar for the remote sensing of volcanic ash cloud. In this respect, radar observations can be complementary to satellite observations. A microphysical electromagnetic characterization of volcanic ash was carried out in terms of dielectric properties, composition, size and orientation of ash particles. An extended Volcanic Ash Radar

  9. Application of wind-profiling radar data to the analysis of dust weather in the Taklimakan Desert.

    PubMed

    Wang, Minzhong; Wei, Wenshou; Ruan, Zheng; He, Qing; Ge, Runsheng

    2013-06-01

    The Urumqi Institute of Desert Meteorology of the China Meteorological Administration carried out an atmospheric scientific experiment to detect dust weather using a wind-profiling radar in the hinterland of the Taklimakan Desert in April 2010. Based on the wind-profiling data obtained from this experiment, this paper seeks to (a) analyze the characteristics of the horizontal wind field and vertical velocity of a breaking dust weather in a desert hinterland; (b) calculate and give the radar echo intensity and vertical distribution of a dust storm, blowing sand, and floating dust weather; and (c) discuss the atmosphere dust counts/concentration derived from the wind-profiling radar data. Studies show that: (a) A wind-profiling radar is an upper-air atmospheric remote sensing system that effectively detects and monitors dust. It captures the beginning and ending of a dust weather process as well as monitors the sand and dust being transported in the air in terms of height, thickness, and vertical intensity. (b) The echo intensity of a blowing sand and dust storm weather episode in Taklimakan is about -1~10 dBZ while that of floating dust -1~-15 dBZ, indicating that the dust echo intensity is significantly weaker than that of precipitation but stronger than that of clear air. (c) The vertical shear of horizontal wind and the maintenance of low-level east wind are usually dynamic factors causing a dust weather process in Taklimakan. The moment that the low-level horizontal wind field finds a shear over time, it often coincides with the onset of a sand blowing and dust storm weather process. (d) When a blowing sand or dust storm weather event occurs, the atmospheric vertical velocity tends to be of upward motion. This vertical upward movement of the atmosphere supported with a fast horizontal wind and a dry underlying surface carries dust particles from the ground up to the air to form blown sand or a dust storm.

  10. The design and development of signal-processing algorithms for an airborne x-band Doppler weather radar

    NASA Technical Reports Server (NTRS)

    Nicholson, Shaun R.

    1994-01-01

    Improved measurements of precipitation will aid our understanding of the role of latent heating on global circulations. Spaceborne meteorological sensors such as the planned precipitation radar and microwave radiometers on the Tropical Rainfall Measurement Mission (TRMM) provide for the first time a comprehensive means of making these global measurements. Pre-TRMM activities include development of precipitation algorithms using existing satellite data, computer simulations, and measurements from limited aircraft campaigns. Since the TRMM radar will be the first spaceborne precipitation radar, there is limited experience with such measurements, and only recently have airborne radars become available that can attempt to address the issue of the limitations of a spaceborne radar. There are many questions regarding how much attenuation occurs in various cloud types and the effect of cloud vertical motions on the estimation of precipitation rates. The EDOP program being developed by NASA GSFC will provide data useful for testing both rain-retrieval algorithms and the importance of vertical motions on the rain measurements. The purpose of this report is to describe the design and development of real-time embedded parallel algorithms used by EDOP to extract reflectivity and Doppler products (velocity, spectrum width, and signal-to-noise ratio) as the first step in the aforementioned goals.

  11. Tropical Rainfall Measuring Mission

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Tropical rainfall affects the lives and economics of a majority of the Earth's population. Tropical rain systems, such as hurricanes, typhoons, and monsoons, are crucial to sustaining the livelihoods of those living in the tropics. Excess rainfall can cause floods and great property and crop damage, whereas too little rainfall can cause drought and crop failure. The latent heat release during the process of precipitation is a major source of energy that drives the atmospheric circulation. This latent heat can intensify weather systems, affecting weather thousands of kilometers away, thus making tropical rainfall an important indicator of atmospheric circulation and short-term climate change. Tropical forests and the underlying soils are major sources of many of the atmosphere's trace constituents. Together, the forests and the atmosphere act as a water-energy regulating system. Most of the rainfall is returned to the atmosphere through evaporation and transpiration, and the atmospheric trace constituents take part in the recycling process. Hence, the hydrological cycle provides a direct link between tropical rainfall and the global cycles of carbon, nitrogen, and sulfur, all important trace materials for the Earth's system. Because rainfall is such an important component in the interactions between the ocean, atmosphere, land, and the biosphere, accurate measurements of rainfall are crucial to understanding the workings of the Earth-atmosphere system. The large spatial and temporal variability of rainfall systems, however, poses a major challenge to estimating global rainfall. So far, there has been a lack of rain gauge networks, especially over the oceans, which points to satellite measurement as the only means by which global observation of rainfall can be made. The Tropical Rainfall Measuring Mission (TRMM), jointly sponsored by the National Aeronautics and Space Administration (NASA) of the United States and the National Space Development Agency (NASDA) of

  12. On the Characterization of Rainfall Associated with U.S. Landfalling North Atlantic Tropical Cyclones Based on Satellite Data and Numerical Weather Prediction Outputs

    NASA Astrophysics Data System (ADS)

    Luitel, B. N.; Villarini, G.; Vecchi, G. A.

    2014-12-01

    When we talk about tropical cyclones (TCs), the first things that come to mind are strong winds and storm surge affecting the coastal areas. However, according to the Federal Emergency Management Agency (FEMA) 59% of the deaths caused by TCs since 1970 is due to fresh water flooding. Heavy rainfall associated with TCs accounts for 13% of heavy rainfall events nationwide for the June-October months, with this percentage being much higher if the focus is on the eastern and southern United States. This study focuses on the evaluation of precipitation associated with the North Atlantic TCs that affected the continental United States over the period 2007 - 2012. We evaluate the rainfall associated with these TCs using four satellite based rainfall products: Tropical Rainfall Measuring Mission - Multi-satellite Precipitation Analysis (TMPA; both real-time and research version); Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN); Climate Prediction Center (CPC) MORPHing technique (CMORPH). As a reference data we use gridded rainfall provided by CPC (Daily US Unified Gauge-Based Analysis of Precipitation). Rainfall fields from each of these satellite products are compared to the reference data, providing valuable information about the realism of these products in reproducing the rainfall associated with TCs affecting the continental United States. In addition to the satellite products, we evaluate the forecasted rainfall produced by five state-of-the-art numerical weather prediction (NWP) models: European Centre for Medium-Range Weather Forecasts (ECMWF), UK Met Office (UKMO), National Centers for Environmental Prediction (NCEP), China Meteorological Administration (CMA), and Canadian Meteorological Center (CMC). The skill of these models in reproducing TC rainfall is quantified for different lead times, and discussed in light of the performance of the satellite products.

  13. Physically-based Flood Modeling Driven by Radar Rainfall in the Upper Guadalupe River Basin, Texas

    NASA Astrophysics Data System (ADS)

    Sharif, H. O.; Chintalapudi, S.; El Hassan, A.

    2011-12-01

    The upstream portion of the Guadalupe River Basin (Upper Guadalupe River Basin) is prone to frequent flooding due to its physiographic properties (thin soils, exposed bedrock, and sparse vegetation). The Upper Guadalupe River watershed above Comfort, Texas drains an area of 2,170 square kilometers. This watershed is located at the central part of the Texas Hill Country. This study presents hydrologic analysis of the June 2002, November-2004, and August-2007 flood events that occurred in Upper Guadalupe River Basin. The physically based, distributed-parameter Gridded Surface Subsurface Hydrologic Analysis (GSSHA) hydrologic model was used to simulate the above flooding events. The first event was used in model while the other two were used for validation. GSSHA model was driven by both rain gauge and Multi-sensor Precipitation Estimator (MPE) rainfall inputs. Differences in simulation results were compared in terms of the hydrographs at different locations in the basin as well as the spatial distribution of hydrologic processes. GSSHA simulations driven by MPE rainfall match very well the USGS observed hydrograph. GSSHA simulation driven by rain gauge rainfall for June-2002 storm event underestimated the peak flow.

  14. Assessment of Intensity-Duration-Frequency curves for the Eastern Mediterranean region derived from high-resolution satellite and radar rainfall estimates

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Morin, Efrat; Peleg, Nadav; Mei, Yiwen; Anagnostou, Emmanouil N.

    2016-04-01

    Intensity-duration-frequency (IDF) curves are used in flood risk management and hydrological design studies to relate the characteristics of a rainfall event to the probability of its occurrence. The usual approach relies on long records of raingauge data providing accurate estimates of the IDF curves for a specific location, but whose representativeness decreases with distance. Radar rainfall estimates have recently been tested over the Eastern Mediterranean area, characterized by steep climatological gradients, showing that radar IDF curves generally lay within the raingauge confidence interval and that radar is able to identify the climatology of extremes. Recent availability of relatively long records (>15 years) of high resolution satellite rainfall information allows to explore the spatial distribution of extreme rainfall with increased detail over wide areas, thus providing new perspectives for the study of precipitation regimes and promising both practical and theoretical implications. This study aims to (i) identify IDF curves obtained from radar rainfall estimates and (ii) identify and assess IDF curves obtained from two high resolution satellite retrieval algorithms (CMORPH and PERSIANN) over the Eastern Mediterranean region. To do so, we derive IDF curves fitting a GEV distribution to the annual maxima series from 23 years (1990-2013) of carefully corrected data from a C-Band radar located in Israel (covering Mediterranean to arid climates) as well as from 15 years (1998-2014) of gauge-adjusted high-resolution CMORPH and 10 years (2003-2013) of gauge-adjusted high-resolution PERSIANN data. We present the obtained IDF curves and we compare the curves obtained from the satellite algorithms to the ones obtained from the radar during overlapping periods; this analysis will draw conclusions on the reliability of the two satellite datasets for deriving rainfall frequency analysis over the region and provide IDF corrections. We compare then the curves obtained

  15. Spaceborne meteorological radar studies

    NASA Technical Reports Server (NTRS)

    Meneghini, R.

    1988-01-01

    Various radar designs and methods are studied for the estimation of rainfall parameters from space. An immediate goal is to support the development of the spaceborne radar that has been proposed for the Tropical Rain Measuring Mission (TRMM). The effort is divided into two activities: a cooperative airborne rain measuring experiment with the Radio Research Laboratory of Japan (RRL), and the modelling of spaceborne weather radars. An airborne rain measuring experiment was conducted at Wallops Flight Facility in 1985 to 1986 using the dual-wavelength radar/radiometer developed by RRL. The data are presently being used to test a number of methods that are relevant to spaceborne weather radars. An example is shown of path-averaged rain rates as estimated from three methods: the standard reflectivity rain rate method (Z-R), a dual-wavelength method, and a surface reference method. The results from the experiment shows for the first time the feasibility of using attenuation methods from space. The purposes of the modelling are twofold: to understand in a quantitative manner the relationships between a particular radar design and its capability for estimating precipitation parameters and to help devise and test new methods. The models are being used to study the impact of various TRMM radar designs on the accuracy of rain rate estimation as well as to test the performance of range-profiling algorithms, the mirror-image method, and some recently devised graphical methods for the estimation of the drop size distribution.

  16. The Design Implementation of an Operational, Computer Based Weather Radar System,

    DTIC Science & Technology

    1979-01-01

    process digitised radar data from a narrow beam, fully steerable radar aerial. The data is collected at several low elevation angles. The radar...display is a Mullard 6OSR needle matrix impact mechanism which uses non-sensitised paper of a standard width (58 mm). The printer control circuitry has been

  17. Weather.

    ERIC Educational Resources Information Center

    Ruth, Amy, Ed.

    1996-01-01

    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)…

  18. Rainfall Process Partitioning Using S-PROF Radar Observations Collected During the CalWater Field Campaign Winters

    NASA Astrophysics Data System (ADS)

    White, A. B.; Neiman, P. J.; Creamean, J.; Hughes, M. R.; Moore, B.; Ralph, F. M.; Prather, K. A.

    2011-12-01

    Vertically pointing S-band radar (S-PROF) observations collected during the CalWater field campaign winter wet seasons are analyzed to partition the observed rainfall into three primary categories: brightband (BB) rain, non-brightband (NBB) rain, and convective rain. NBB rain is primarily a shallow, warm rain process driven by collision and coalescence. Because of its shallow nature, NBB rain is often undetected by the operational NEXRAD radar network. Previous rainfall process partitioning analysis conducted for a coastal mountain site in California has shown that NBB rain contributes about one-third, on average, of the total wet season precipitation observed there. Shallow moist flow with near neutral stability, which is often present in the coastal environment during the warm sectors of landfalling storms, is a key ingredient in the formation of NBB rain. However, NBB rain also has been observed in other storm regimes (e.g., post-cold frontal). NBB rain has been shown to produce rain rates known by forecasters to be capable of producing floods. During the CalWater field campaign winters, S-PROF radars were located in the Sierra Nevada at Sugar Pine Dam (SPD) for three consecutive winters (2009-2011) and at Mariposa (MPI) for the latter two winters (2010-2011). During the southwesterly flow present in the warm sectors of many California landfalling storms, the SPD site was directly downwind of the gap in coastal terrain associated with the San Francisco Bay Delta. This orientation would allow relatively unmodified maritime flow to arrive at SPD. The MPI site was located further south such that airflow arriving at this site during winter storms likely was processed by the coastal terrain south of San Francisco Bay. In this presentation we will examine whether the relative locations of SPD and MPI relative to the coastal terrain impacted the amount of NBB rain that was observed at each site during the CalWater wet seasons. We will use synoptic and mesoscale

  19. Whirl Wind Detection and Identification in Indonesia Utilizing Single Polarization Doppler Weather Radar Volumetric Data

    NASA Astrophysics Data System (ADS)

    Ali, Abdullah; Hidayati, Sabitul

    2016-06-01

    Whirl wind occurrence frequency in Indonesia tends increasing in the last five years. Geospatial data from National Agency for Disaster Management (BNPB) recorded 72 cases with the impact of the two victims died, ten injured, 485 people were evacuated, and 1285 buildings were destroyed at period of January-June 2015. Based on the impact, early warning through remote sensing by using single polarization Doppler weather radar is need to be efforted. Whirl wind detection is done by identifying the characteristic pattern of the rotating convective cloud system by hook echo, analyzing the exsistance of vortex and rotation, and the strength of turbulence. The results show horizontal wind profile with a rotational pattern at CAPPI (V) and HWIND (V) by the altitude of 0.5 km, strong turbulence through product CAPPI (W) 0.5 km ranged of 1.75-2.05 ms-1, the vertical wind profile by product VVP (V) with a maximum value updraft reaches more than 20 knots at a 100-200 meters height, strong horizontal wind shear through HSHEAR (V) and CAPPI (HSHEAR) altitude of 0.5 km with a range of 6.23 to 10.12 ms-1/km. SWI and SSA show that the cloud base height is very low ranged from 200-600 meters with a maximum reflectivity reached 61.5 dBZ by top cloud height reached 14 km, while the product CAPPI (Z) 0.5 km and CMAX (Z) is very difficult to identify patterns hook echo. The results of remote sensing are very representative with the physical properties of whirl wind even whirl wind in a smaller scale.

  20. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground based weather radar network over Sweden

    NASA Astrophysics Data System (ADS)

    Norin, L.; Devasthale, A.; L'Ecuyer, T. S.; Wood, N. B.; Smalley, M.

    2015-08-01

    To be able to estimate snowfall accurately is important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain-gauges to estimate precipitation in this context. The Cloud Profiling Radar (CPR) onboard CloudSat is especially proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and ability to provide near-global vertical structure. The importance of having snowfall estimates from CloudSat/CPR further increases in the high latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. Here we intercompared snowfall estimates from two observing systems, CloudSat and Swerad, the Swedish national weather radar network. Swerad offers one of the best calibrated data sets of precipitation amount at very high latitudes that are anchored to rain-gauges and that can be exploited to evaluate usefulness of CloudSat/CPR snowfall estimates in the polar regions. In total 7.2×105 matchups of CloudSat and Swerad over Sweden were inter-compared covering all but summer months (October to May) from 2008 to 2010. The intercomparison shows encouraging agreement between these two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46-82 km), when the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station as Swerad's sensitivity decreases as a function of distance and Swerad also tends to overshoots low level precipitating systems further away from the station, leading to underestimation of snowfall rate and occasionally missing

  1. Detection and estimation of volcanic eruption onset and mass flow rate using weather radar and infrasonic array

    NASA Astrophysics Data System (ADS)

    Marzano, Frank S.; Mereu, Luigi; Montopoli, Mario; Picciotti, Errico; Di Fabio, Saverio; Bonadonna, Costanza; Marchetti, Emanuele; Ripepe, Maurizio

    2015-04-01

    The explosive eruption of sub-glacial Eyjafjallajökull volcano in 2010 was of modest size, but ash was widely dispersed over Iceland and Europe. The Eyjafjallajökull pulsating explosive activity started on April 14 and ended on May 22. The combination of a prolonged and sustained ejection of volcanic ash and persistent northwesterly winds resulted in dispersal the volcanic cloud over a large part of Europe. Tephra dispersal from an explosive eruption is a function of multiple factors, including magma mass flow rate (MFR), degree of magma fragmentation, vent geometry, plume height, particle size distribution (PSD) and wind velocity. One of the most important geophysical parameters, derivable from the analysis of tephra deposits, is the erupted mass, which is essential for the source characterization and assessment of the associated hazards. MFR can then be derived by dividing the erupted mass by the eruption duration (if known) or based on empirical and analytical relations with plume height. Microwave weather radars at C and X band can provide plume height, ash concentration and loading, and, to some extent, PSD and MFR. Radar technology is well established and can nowadays provide fast three-dimensional (3D) scanning antennas together with Doppler and dual polarization capabilities. However, some factors can limit the detection and the accuracy of the radar products aforementioned. For example, the sensitivity of microwave radar measurements depends on the distance between the radar antenna and the target, the transmitter central wavelength, receiver minimum detachable power and the resolution volume. In addition, radar measurements are sensitive to particle sizes larger than few tens of microns thus limiting the radar-based quantitative estimates to the larger portion of the PSD. Volcanic activity produces infrasonic waves (i.e., acoustic waves below 20 Hz), which can propagate in the atmosphere useful for the remote monitoring of volcanic activity. Infrasound

  2. Potential use of radar QPE for hydrological design

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Morin, Efrat

    2014-05-01

    Intensity-duration-frequency (IDF) curves are commonly used for flood management design, and are identified from rainfall records analyzing maximum intensity values for a set of given durations. This approach applies to raingauge measurements even if usual design applications would prefer catchment scale curves. Weather radar provides distributed rainfall estimates with high spatial and temporal resolutions; in this way it is able to exploit the dynamics and variability of extreme rainfall events over wide areas. Two main objections usually restrain this approach: the length of radar data records and the reliability of radar quantitative precipitation estimations (QPE). This work aims to explore the feasibility of using radar QPE for the identification of IDF curves by means of a long length radar data archive and a combined physical- and quantitative- adjustment of radar rainfall estimates. Two C-Band weather radars are located in the eastern Mediterranean area (Tel Aviv, Israel) and are operational since 1990 and 1997 respectively, providing relatively long-term records. Radar measurements are elaborated using physically-based correction algorithms and are then adjusted by removing the mean field bias with respect to ground observations. Accuracy of radar QPE is assessed by comparison with raingauge measurements using a bootstrap technique. IDF curves are calculated for a set of reference raingauges using different sources of rainfall information: i) raingauge data record ("true" IDF), ii) data record of the closest raingauge and iii) radar QPE obtained excluding the examined raingauge from the adjustment procedure. Accuracy of radar-based IDF compared to close by-raingauge IDF is assessed. Results of this on-going study will be presented leading to conclusions on the potential use of radar QPE for IDF estimation.

  3. Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

    NASA Technical Reports Server (NTRS)

    Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

    1986-01-01

    The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

  4. Simultaneous ocean cross-section and rainfall measurements from space with a nadir-pointing radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Atlas, D.

    1984-01-01

    A method to determine simultaneously the rainfall rate and the normalized backscattering cross section of the surface was evaluated. The method is based on the mirror reflected power, p sub m which corresponds to the portion of the incident power scattered from the surface to the precipitation, intercepted by the precipitation, and again returned to the surface where it is scattered a final time back to the antenna. Two approximations are obtained for P sub m depending on whether the field of view at the surface is either much greater or much less than the height of the reflection layer. Since the dependence of P sub m on the backscattering cross section of the surface differs in the two cases, two algorithms are given by which the path averaged rain rate and normalized cross section are deduced. The detectability of P sub m, the relative strength of other contributions to the return power arriving simultaneous with P sub m, and the validity of the approximations used in deriving P sub m are discussed.

  5. Comparison of Two Methods for Estimating the Sampling-Related Uncertainty of Satellite Rainfall Averages Based on a Large Radar Data Set

    NASA Technical Reports Server (NTRS)

    Lau, William K. M. (Technical Monitor); Bell, Thomas L.; Steiner, Matthias; Zhang, Yu; Wood, Eric F.

    2002-01-01

    The uncertainty of rainfall estimated from averages of discrete samples collected by a satellite is assessed using a multi-year radar data set covering a large portion of the United States. The sampling-related uncertainty of rainfall estimates is evaluated for all combinations of 100 km, 200 km, and 500 km space domains, 1 day, 5 day, and 30 day rainfall accumulations, and regular sampling time intervals of 1 h, 3 h, 6 h, 8 h, and 12 h. These extensive analyses are combined to characterize the sampling uncertainty as a function of space and time domain, sampling frequency, and rainfall characteristics by means of a simple scaling law. Moreover, it is shown that both parametric and non-parametric statistical techniques of estimating the sampling uncertainty produce comparable results. Sampling uncertainty estimates, however, do depend on the choice of technique for obtaining them. They can also vary considerably from case to case, reflecting the great variability of natural rainfall, and should therefore be expressed in probabilistic terms. Rainfall calibration errors are shown to affect comparison of results obtained by studies based on data from different climate regions and/or observation platforms.

  6. Meteorological Studies with the Phased Array Weather Radar and Data Assimilation Using the Ensemble Kalman Filter

    DTIC Science & Technology

    2008-09-30

    was included. (4) Technology Innovation: Spectral processing was identified by Fabry and Keeler (2003) as one of the trends in meteorological radar...University College London, 227 pp. Fabry, F. and R. J. Keeler : 2003, Innovative signal utilization and processing. Radar and Atmospheric Science

  7. A nonlinear spatio-temporal lumping of radar rainfall for modeling multi-step-ahead inflow forecasts by data-driven techniques

    NASA Astrophysics Data System (ADS)

    Chang, Fi-John; Tsai, Meng-Jung

    2016-04-01

    Accurate multi-step-ahead inflow forecasting during typhoon periods is extremely crucial for real-time reservoir flood control. We propose a spatio-temporal lumping of radar rainfall for modeling inflow forecasts to mitigate time-lag problems and improve forecasting accuracy. Spatial aggregation of radar cells is made based on the sub-catchment partitioning obtained from the Self-Organizing Map (SOM), and then flood forecasting is made by the Adaptive Neuro Fuzzy Inference System (ANFIS) models coupled with a 2-staged Gamma Test (2-GT) procedure that identifies the optimal non-trivial rainfall inputs. The Shihmen Reservoir in northern Taiwan is used as a case study. The results show that the proposed methods can, in general, precisely make 1- to 4-hour-ahead forecasts and the lag time between predicted and observed flood peaks could be mitigated. The constructed ANFIS models with only two fuzzy if-then rules can effectively categorize inputs into two levels (i.e. high and low) and provide an insightful view (perspective) of the rainfall-runoff process, which demonstrate their capability in modeling the complex rainfall-runoff process. In addition, the confidence level of forecasts with acceptable error can reach as high as 97% at horizon t+1 and 77% at horizon t+4, respectively, which evidently promotes model reliability and leads to better decisions on real-time reservoir operation during typhoon events.

  8. 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)

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

    2007-12-01

    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

  9. Advanced Polarimetric Measurements and Analysis with the CSD-CHILL Weather Radar

    DTIC Science & Technology

    1998-09-20

    echo with respect to increased range. Shown in Fig. 9 is an example of three-body scattering from DLR’s (German Aerospace Agency) C - band radar located...Seeliger ground model for (a) S- band and (b) C - band . There are three sets of curves in each plot corresponding to radar beam heights at 0.01, 0.1 and...reflectivity, Preprints 25th Conf. Radar Meteor., 8-12 Sept., Austin, TX. 10. Brunkow, D., P. C . Kennedy, S. A. Rutledge, V. N. Bringi and V

  10. Developing Dual Polarization Applications For 45th Weather Squadron's (45 WS) New Weather Radar: A Cooperative Project With The National Space Science and Technology Center (NSSTC)

    NASA Technical Reports Server (NTRS)

    Roeder, W.P.; Peterson, W.A.; Carey, L.D.; Deierling, W.; McNamara, T.M.

    2009-01-01

    A new weather radar is being acquired for use in support of America s space program at Cape Canaveral Air Force Station, NASA Kennedy Space Center, and Patrick AFB on the east coast of central Florida. This new radar includes dual polarization capability, which has not been available to 45 WS previously. The 45 WS has teamed with NSSTC with funding from NASA Marshall Spaceflight Flight Center to improve their use of this new dual polarization capability when it is implemented operationally. The project goals include developing a temperature profile adaptive scan strategy, developing training materials, and developing forecast techniques and tools using dual polarization products. The temperature profile adaptive scan strategy will provide the scan angles that provide the optimal compromise between volume scan rate, vertical resolution, phenomena detection, data quality, and reduced cone-of-silence for the 45 WS mission. The mission requirements include outstanding detection of low level boundaries for thunderstorm prediction, excellent vertical resolution in the atmosphere electrification layer between 0 C and -20 C for lightning forecasting and Lightning Launch Commit Criteria evaluation, good detection of anvil clouds for Lightning Launch Commit Criteria evaluation, reduced cone-of-silence, fast volume scans, and many samples per pulse for good data quality. The training materials will emphasize the appropriate applications most important to the 45 WS mission. These include forecasting the onset and cessation of lightning, forecasting convective winds, and hopefully the inference of electrical fields in clouds. The training materials will focus on annotated radar imagery based on products available to the 45 WS. Other examples will include time sequenced radar products without annotation to simulate radar operations. This will reinforce the forecast concepts and also allow testing of the forecasters. The new dual polarization techniques and tools will focus on

  11. Country-wide rainfall maps from a commercial cellular telephone network

    NASA Astrophysics Data System (ADS)

    Overeem, A.; Leijnse, H.; Uijlenhoet, R.

    2012-04-01

    Accurate rainfall observations with high spatial and temporal resolutions are needed for many applications, for instance, as input for hydrological models. Weather radars often provide data with sufficient spatial and temporal resolution, but usually need adjustment. In general, only few rain gauge measurements are available to adjust the radar data in real-time, for example, each hour. Physically based methods, such as a VPR correction, can be valuable and hold a promise. However, they are not always performed in real-time yet and can be difficult to implement. The estimation of rainfall using microwave links from commercial cellular telephone networks is a new and potentially valuable source of information. Such networks cover large parts of the land surface of the earth and have a high density. The data produced by the microwave links in such networks is essentially a by-product of the communication between mobile telephones. Rainfall attenuates the electromagnetic signals transmitted from one telephone tower to another. By measuring the received power at one end of a microwave link as a function of time, the path-integrated attenuation due to rainfall can be calculated. Previous studies have shown that average rainfall intensities over the length of a link can be derived from the path-integrated attenuation. A recent study of us shows that urban rainfall can be estimated from commercial microwave link data for the Rotterdam region, a densely-populated delta city in the Netherlands. A data set from a commercial microwave link network over the Netherlands is analyzed, containing approximately 1500 links covering the land surface of the Netherlands (35500 km2). This data set consists of several days with extreme rainfall in June, July and August 2011. A methodology is presented to derive rainfall intensities and daily rainfall depths from the microwave link data, which have a temporal resolution of 15 min. The magnitude and dynamics of these rainfall intensities

  12. Range profiling of the rain rate by an airborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Nakamura, Kenji

    1990-01-01

    A class of methods based on a measure of path attenuation that is used to constrain the Hitschfeld-Bordan solution is investigated. Such methods are investigated for lidar, radar, and combined radar-radiometer applications. Their function is to allocate the attenuation in proportion to the strength of the measured reflectivity. A description is provided of four estimates of rain rate that have been tested using data from a dual-wavelength airborne radar at 10 GHz and 35 GHz. It is concluded, that when attenuation is significant, the estimates are generally more accurate than those without attenuation correction. Thus, such methodologies can be utilized to extend the effective dynamic range of the radar to higher rain rates.

  13. Observations of Kelvin-Helmholtz instability at a cloud base with the middle and upper atmosphere (MU) and weather radars

    NASA Astrophysics Data System (ADS)

    Luce, Hubert; Mega, Tomoaki; Yamamoto, Masayuki K.; Yamamoto, Mamoru; Hashiguchi, Hiroyuki; Fukao, Shoichiro; Nishi, Noriyuki; Tajiri, Takuya; Nakazato, Masahisa

    2010-10-01

    Using the very high frequency (46.5 MHz) middle and upper atmosphere radar (MUR), Ka band (35 GHz) and X band (9.8 GHz) weather radars, a Kelvin-Helmholtz (KH) instability occurring at a cloud base and its impact on modulating cloud bottom altitudes are described by a case study on 8 October 2008 at the Shigaraki MU Observatory, Japan (34.85°N, 136.10°E). KH braids were monitored by the MUR along the slope of a cloud base gradually rising with time around an altitude of ˜5.0 km. The KH braids had a horizontal wavelength of about 3.6 km and maximum crest-to-trough amplitude of about 1.6 km. Nearly monochromatic and out of phase vertical air motion oscillations exceeding ±3 m s-1 with a period of ˜3 min 20 s were measured by the MUR above and below the cloud base. The axes of the billows were at right angles of the wind and wind shear both oriented east-north-east at their altitude. The isotropy of the radar echoes and the large variance of Doppler velocity in the KH billows (including the braids) indicate the presence of strong turbulence at the Bragg (˜3.2 m) scale. After the passage of the cloud system, the KH waves rapidly damped and the vertical scale of the KH braids progressively decreased down to about 100 m before their disappearance. The radar observations suggest that the interface between clear air and cloud was conducive to the presence of the dynamical shear instability by reducing static stability (and then the Richardson number) near the cloud base. Downward cloudy protuberances detected by the Ka band radar had vertical and horizontal scales of about 0.6-1.1 and 3.2 km, respectively, and were clearly associated with the downward air motions. Observed oscillations of the reflectivity-weighted Doppler velocity measured by the X band radar indicate that falling ice particles underwent the vertical wind motions generated by the KH instability to form the protuberances. The protuberances at the cloud base might be either KH billow clouds or perhaps

  14. Adaptive clutter rejection filters for airborne Doppler weather radar applied to the detection of low altitude windshear

    NASA Technical Reports Server (NTRS)

    Keel, Byron M.

    1989-01-01

    An optimum adaptive clutter rejection filter for use with airborne Doppler weather radar is presented. The radar system is being designed to operate at low-altitudes for the detection of windshear in an airport terminal area where ground clutter returns may mask the weather return. The coefficients of the adaptive clutter rejection filter are obtained using a complex form of a square root normalized recursive least squares lattice estimation algorithm which models the clutter return data as an autoregressive process. The normalized lattice structure implementation of the adaptive modeling process for determining the filter coefficients assures that the resulting coefficients will yield a stable filter and offers possible fixed point implementation. A 10th order FIR clutter rejection filter indexed by geographical location is designed through autoregressive modeling of simulated clutter data. Filtered data, containing simulated dry microburst and clutter return, are analyzed using pulse-pair estimation techniques. To measure the ability of the clutter rejection filters to remove the clutter, results are compared to pulse-pair estimates of windspeed within a simulated dry microburst without clutter. In the filter evaluation process, post-filtered pulse-pair width estimates and power levels are also used to measure the effectiveness of the filters. The results support the use of an adaptive clutter rejection filter for reducing the clutter induced bias in pulse-pair estimates of windspeed.

  15. An investigation of a new dual-polarization weather radar data model for lightning nowcasting and warning

    NASA Astrophysics Data System (ADS)

    Ruzanski, Evan; Chandrasekar, Venkatachalam

    2016-04-01

    Accurate and extended short-term automated forecasting (nowcasting) of lightning is important for the preservation of life and resources in many applications. A new dual-polarization weather radar data model for lightning nowcasting and warning is presented and described. Previous research has shown that a simplified radar-based ice mass estimator provides value in lightning nowcasting and warning. This new product estimates the mass of graupel aloft, a quantity shown to be a key component in the atmospheric electrification process. The mass of graupel in the charge region of the storm is estimated by a model comprised of integrated reflectivity above the environmental freezing level, classification of graupel regions by a new hydrometeor classification algorithm, and coefficients determined by bulk microphysics studies. Data from storm events collected by the KFWS WSR-88D and National Lightning Detection Network in the Dallas-Fort Worth urban area in 2014 are used for analysis. Nowcasting is done using an area-based approach called the Dynamic and Adaptive Radar Tracking of Storms, where storm motion is estimated using a Fourier-based linear model. Nowcasts are then generated by advecting the data fields ahead in time according to these estimated motion vectors. Warning verification in the 0-1 h lead time frame is performed using a grid-based approach that discerns the performance of first-lightning flash nowcasting at each grid point.

  16. Assessment of Rainfall Estimates Using a Standard Z-R Relationship and the Probability Matching Method Applied to Composite Radar Data in Central Florida

    NASA Technical Reports Server (NTRS)

    Crosson, William L.; Duchon, Claude E.; Raghavan, Ravikumar; Goodman, Steven J.

    1996-01-01

    Precipitation estimates from radar systems are a crucial component of many hydrometeorological applications, from flash flood forecasting to regional water budget studies. For analyses on large spatial scales and long timescales, it is frequently necessary to use composite reflectivities from a network of radar systems. Such composite products are useful for regional or national studies, but introduce a set of difficulties not encountered when using single radars. For instance, each contributing radar has its own calibration and scanning characteristics, but radar identification may not be retained in the compositing procedure. As a result, range effects on signal return cannot be taken into account. This paper assesses the accuracy with which composite radar imagery can be used to estimate precipitation in the convective environment of Florida during the summer of 1991. Results using Z = 30OR(sup 1.4) (WSR-88D default Z-R relationship) are compared with those obtained using the probability matching method (PMM). Rainfall derived from the power law Z-R was found to he highly biased (+90%-l10%) compared to rain gauge measurements for various temporal and spatial integrations. Application of a 36.5-dBZ reflectivity threshold (determined via the PMM) was found to improve the performance of the power law Z-R, reducing the biases substantially to 20%-33%. Correlations between precipitation estimates obtained with either Z-R relationship and mean gauge values are much higher for areal averages than for point locations. Precipitation estimates from the PMM are an improvement over those obtained using the power law in that biases and root-mean-square errors are much lower. The minimum timescale for application of the PMM with the composite radar dataset was found to be several days for area-average precipitation. The minimum spatial scale is harder to quantify, although it is concluded that it is less than 350 sq km. Implications relevant to the WSR-88D system are

  17. Applicability of open rainfall data to event-scale urban rainfall-runoff modelling

    NASA Astrophysics Data System (ADS)

    Niemi, Tero J.; Warsta, Lassi; Taka, Maija; Hickman, Brandon; Pulkkinen, Seppo; Krebs, Gerald; Moisseev, Dmitri N.; Koivusalo, Harri; Kokkonen, Teemu

    2017-04-01

    Rainfall-runoff simulations in urban environments require meteorological input data with high temporal and spatial resolutions. The availability of precipitation data is constantly increasing due to the shift towards more open data sharing. However, the applicability of such data for urban runoff assessments is often unknown. Here, the feasibility of Finnish Meteorological Institute's open rain gauge and open weather radar data as input sources was studied by conducting Storm Water Management Model simulations at a very small (33.5 ha) urban catchment in Helsinki, Finland. In addition to the open data sources, data were also available from two research gauges, one of them located on-site, and from a research radar. The results confirmed the importance of local precipitation measurements for urban rainfall-runoff simulations, implying the suitability of open gauge data to be largely dictated by the gauge's distance from the catchment. Performance of open radar data with 5 min and 1 km2 resolution was acceptable in terms of runoff reproduction, albeit peak flows were constantly and flow volumes often underestimated. Gauge adjustment and advection interpolation were found to improve the quality of the radar data, and at least gauge adjustment should be performed when open radar data are used. Finally, utilizing dual-polarization capabilities of radars has a potential to improve rainfall estimates for high intensity storms although more research is still needed.

  18. The Use of Radar-Based Products for Deriving Extreme Rainfall Frequencies Using Regional Frequency Analysis with Application in South Louisiana

    NASA Astrophysics Data System (ADS)

    El-Dardiry, H. A.; Habib, E. H.

    2014-12-01

    Radar-based technologies have made spatially and temporally distributed quantitative precipitation estimates (QPE) available in an operational environmental compared to the raingauges. The floods identified through flash flood monitoring and prediction systems are subject to at least three sources of uncertainties: (a) those related to rainfall estimation errors, (b) those due to streamflow prediction errors due to model structural issues, and (c) those due to errors in defining a flood event. The current study focuses on the first source of uncertainty and its effect on deriving important climatological characteristics of extreme rainfall statistics. Examples of such characteristics are rainfall amounts with certain Average Recurrence Intervals (ARI) or Annual Exceedance Probability (AEP), which are highly valuable for hydrologic and civil engineering design purposes. Gauge-based precipitation frequencies estimates (PFE) have been maturely developed and widely used over the last several decades. More recently, there has been a growing interest by the research community to explore the use of radar-based rainfall products for developing PFE and understand the associated uncertainties. This study will use radar-based multi-sensor precipitation estimates (MPE) for 11 years to derive PFE's corresponding to various return periods over a spatial domain that covers the state of Louisiana in southern USA. The PFE estimation approach used in this study is based on fitting generalized extreme value distribution to hydrologic extreme rainfall data based on annual maximum series (AMS). Some of the estimation problems that may arise from fitting GEV distributions at each radar pixel is the large variance and seriously biased quantile estimators. Hence, a regional frequency analysis approach (RFA) is applied. The RFA involves the use of data from different pixels surrounding each pixel within a defined homogenous region. In this study, region of influence approach along with the

  19. A seamless flash-flood early warning tool based on IDF-curves and coupling of weather-radar with numerical weather predictions

    NASA Astrophysics Data System (ADS)

    Liechti, Kaethi; Knechtl, Valentin; Andres, Norina; Sideris, Ioannis; Zappa, Massimiliano

    2014-05-01

    A flash-flood is a flood that develops rapidly after a heavy precipitation event. Flash-flood forecasting is an important field of research because flash floods cause a lot of fatalities and damage. A flash-flood early warning tool is developed based on precipitation statistics. Our target areas are small ungauged areas of southern-Switzerland. A total of 759 sub-cathcments was considered. In a first intensity-duration-frequency (IDF) curves for each catchment have been calculated basin on: A) Gridded precipitation products for the period 1961 to 2012 and B) gridded reforecast of the COSMO-LEPS NWP for the period 1971-2000. These different IDF-curves at the catchment level in combination with precipitation forecasts are the basis for the flash-flood early warning tool. The forecast models used are COSMO-2 (deterministic, updated every three hours and with a lead time of 24 hours) and COSMO-LEPS (probabilistic, 16 member and with a lead time of five days). In operational mode COSMO-2 is nudged to real-time data of a weather-radar precipitation obtained by blending the radar qpe with information from a national network of precipitation data. This product is called COMBIPRECIP. The flash-flood early warning tool has been evaluated against observed events. These events are either discharge peaks in gauged sub-areas or reports of damages caused by flash-flood events. The hypothesis that it is possible to detect hydrological events with the flash-flood early warning tool can be partly confirmed. The highest skill is obtained if the return-period of weather radar QPE is assessed at hourly time scale. With this it was possible to confirm most of the damage events occurred in 2010 and 2011. The prototype tool is affected by several false alarms. This is because initial conditions of the soils are not considered. Further steps will be therefore focussed on the addition of real-time hydrological information as obtained from the application of high resolution distributed

  20. Flash flood warning in mountaineous areas using X-band weather radars and the AIGA method in the framework of the RHYTMME project

    NASA Astrophysics Data System (ADS)

    Javelle, Pierre; Defrance, Dimitri; Ecrepont, Stéphane; Fouchier, Catherine; Mériaux, Patrice; Tolsa, Mathieu; Westrelin, Samuel

    2013-04-01

    The knowledge of precipitations still remains a tricky issue in mountaineous areas: the available rain-gauges are in a limited number and most often located in the valleys, and the radar rainfall estimates have to deal with a lot of problems due to the relief and the difficulty to distinguish the different types of hydrometeors (snow, hail, rain). In this context, the "RHYTMME" project deals with two main issues: - Providing an accurate radar rainfall information in mountainous areas. - Developing a real-time hazards warning system based on this information. To answer to the first issue, a X-band doppler dual polarized radar network is currently implemented in the French South Alps. At the end of the project (2013), three new radars will be installed, completing a pre-existing radar already installed on the Mont Vial top since 2008 (Hydrix® technology developed by the Novimet company, and tested in a previous project). The present communication focuses on the flash flood warning issue. It presents some results obtained by coupling the radar estimates to a simple distributed hydrological model (the AIGA method). Results are compared on damages observed by end-users, which were strongly involved into the project. The RHYTMME project is co-piloted by Meteo-France and the Cemagref and has the financial support of the European Union, the Provence-Alpes-Côte d'Azur Region and the French Ministry in charge of Ecology.

  1. Radar QPE for hydrological design: Intensity-Duration-Frequency curves

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Morin, Efrat

    2015-04-01

    Intensity-duration-frequency (IDF) curves are widely used in flood risk management since they provide an easy link between the characteristics of a rainfall event and the probability of its occurrence. They are estimated analyzing the extreme values of rainfall records, usually basing on raingauge data. This point-based approach raises two issues: first, hydrological design applications generally need IDF information for the entire catchment rather than a point, second, the representativeness of point measurements decreases with the distance from measure location, especially in regions characterized by steep climatological gradients. Weather radar, providing high resolution distributed rainfall estimates over wide areas, has the potential to overcome these issues. Two objections usually restrain this approach: (i) the short length of data records and (ii) the reliability of quantitative precipitation estimation (QPE) of the extremes. This work explores the potential use of weather radar estimates for the identification of IDF curves by means of a long length radar archive and a combined physical- and quantitative- adjustment of radar estimates. Shacham weather radar, located in the eastern Mediterranean area (Tel Aviv, Israel), archives data since 1990 providing rainfall estimates for 23 years over a region characterized by strong climatological gradients. Radar QPE is obtained correcting the effects of pointing errors, ground echoes, beam blockage, attenuation and vertical variations of reflectivity. Quantitative accuracy is then ensured with a range-dependent bias adjustment technique and reliability of radar QPE is assessed by comparison with gauge measurements. IDF curves are derived from the radar data using the annual extremes method and compared with gauge-based curves. Results from 14 study cases will be presented focusing on the effects of record length and QPE accuracy, exploring the potential application of radar IDF curves for ungauged locations and

  2. Methods of Attenuation Correction for Dual-Wavelength and Dual-Polarization Weather Radar Data

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Liao, L.

    2007-01-01

    In writing the integral equations for the median mass diameter and number concentration, or comparable parameters of the raindrop size distribution, it is apparent that the forms of the equations for dual-polarization and dual-wavelength radar data are identical when attenuation effects are included. The differential backscattering and extinction coefficients appear in both sets of equations: for the dual-polarization equations, the differences are taken with respect to polarization at a fixed frequency while for the dual-wavelength equations, the differences are taken with respect to frequency at a fixed polarization. An alternative to the integral equation formulation is that based on the k-Z (attenuation coefficient-radar reflectivity factor) parameterization. This-technique was originally developed for attenuating single-wavelength radars, a variation of which has been applied to the TRMM Precipitation Radar data (PR). Extensions of this method have also been applied to dual-polarization data. In fact, it is not difficult to show that nearly identical equations are applicable as well to dualwavelength radar data. In this case, the equations for median mass diameter and number concentration take the form of coupled, but non-integral equations. Differences between this and the integral equation formulation are a consequence of the different ways in which attenuation correction is performed under the two formulations. For both techniques, the equations can be solved either forward from the radar outward or backward from the final range gate toward the radar. Although the forward-going solutions tend to be unstable as the attenuation out to the range of interest becomes large in some sense, an independent estimate of path attenuation is not required. This is analogous to the case of an attenuating single-wavelength radar where the forward solution to the Hitschfeld-Bordan equation becomes unstable as the attenuation increases. To circumvent this problem, the

  3. On the Tropical Rainfall Measuring Mission (TRMM): Bringing NASA's Earth System Science Program to the Classroom

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall

    1998-01-01

    The Tropical Rainfall Measuring Mission is the first mission dedicated to measuring tropical and subtropical rainfall using a variety of remote sensing instrumentation, including the first spaceborne rain-measuring radar. Since the energy released when tropical rainfall occurs is a primary "fuel" supply for the weather and climate "engine"; improvements in computer models which predict future weather and climate states may depend on better measurements of global tropical rainfall and its energy. In support of the STANYS conference theme of Education and Space, this presentation focuses on one aspect of NASA's Earth Systems Science Program. We seek to present an overview of the TRMM mission. This overview will discuss the scientific motivation for TRMM, the TRMM instrument package, and recent images from tropical rainfall systems and hurricanes. The presentation also targets educational components of the TRMM mission in the areas of weather, mathematics, technology, and geography that can be used by secondary school/high school educators in the classroom.

  4. Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars

    NASA Astrophysics Data System (ADS)

    Mishra, Kumar Vijay

    The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi

  5. Characterizing response of total suspended solids and total phosphorus loading to weather and watershed characteristics for rainfall and snowmelt events in agricultural watersheds

    USGS Publications Warehouse

    Danz, Mari E.; Corsi, Steven; Brooks, Wesley R.; Bannerman, Roger T.

    2013-01-01

    Understanding the response of total suspended solids (TSS) and total phosphorus (TP) to influential weather and watershed variables is critical in the development of sediment and nutrient reduction plans. In this study, rainfall and snowmelt event loadings of TSS and TP were analyzed for eight agricultural watersheds in Wisconsin, with areas ranging from 14 to 110 km2 and having four to twelve years of data available. The data showed that a small number of rainfall and snowmelt runoff events accounted for the majority of total event loading. The largest 10% of the loading events for each watershed accounted for 73–97% of the total TSS load and 64–88% of the total TP load. More than half of the total annual TSS load was transported during a single event for each watershed at least one of the monitored years. Rainfall and snowmelt events were both influential contributors of TSS and TP loading. TSS loading contributions were greater from rainfall events at five watersheds, from snowmelt events at two watersheds, and nearly equal at one watershed. The TP loading contributions were greater from rainfall events at three watersheds, from snowmelt events at two watersheds and nearly equal at three watersheds. Stepwise multivariate regression models for TSS and TP event loadings were developed separately for rainfall and snowmelt runoff events for each individual watershed and for all watersheds combined by using a suite of precipitation, melt, temperature, seasonality, and watershed characteristics as predictors. All individual models and the combined model for rainfall events resulted in two common predictors as most influential for TSS and TP. These included rainfall depth and the antecedent baseflow. Using these two predictors alone resulted in an R2 greater than 0.7 in all but three individual models and 0.61 or greater for all individual models. The combined model yielded an R2 of 0.66 for TSS and 0.59 for TP. Neither the individual nor the combined models were

  6. Detection of Digital Elevation Model Errors Using X-band Weather Radar

    NASA Technical Reports Server (NTRS)

    Young, Steven D.; deHaag, Maatren Uijt

    2007-01-01

    Flight in Instrument Meteorological Conditions requires pilots to manipulate flight controls while referring to a Primary Flight Display. The Primary Flight Display indicates aircraft attitude along with, in some cases, many other state variables such as altitude, speed, and guidance cues. Synthetic Vision Systems have been proposed that overlay the traditional information provided on Primary Flight Displays onto a scene depicting the location of terrain and other geo-spatial features.Terrain models used by these displays must have sufficient quality to avoid providing misleading information. This paper describes how X-band radar measurements can be used as part of a monitor, and/or maintenance system, to quantify the integrity of terrain models that are used by systems such as Synthetic Vision. Terrain shadowing effects, as seen by the radar, are compared in a statistical manner against estimated shadow feature elements extracted from the stored terrain model from the perspective of the airborne observer. A test statistic is defined that enables detection of errors as small as the range resolution of the radar. Experimental results obtained from two aircraft platforms hosting certified commercial-off-the-shelf X-band radars test the premise and illustrate its potential.

  7. The use of weather radars to estimate hail damage to automobiles: an exploratory study in Switzerland

    NASA Astrophysics Data System (ADS)

    Hohl, Roman; Schiesser, Hans-Heinrich; Knepper, Ingeborg

    As the first of its kind, this study presents damage functions between two damage variables of hail-damaged automobiles and radar-derived hail kinetic energy for a total of 12 severe hailstorms that have occurred over the Swiss Mittelland (1992-1998). Hail kinetic energy is calculated from C-band Doppler radar CAPPIs at low storm level (1.5 km MSL) and is integrated per radar element ( EKINPIX) for entire hail cells. Hail damage claim data were available per Swiss community on a daily basis and transformed (Delaunay triangulation) along with EKINPIX to a regular 3×3 km grid, thereafter allowing cross-correlation between the variables. The results show nonlinear relationships between EKINPIX and both loss ratios and mean damages per hail-damaged car, differing between high hail season storms (15 June-15 August) and storms that occurred during the low season (before and after). A weighted logistic function provides correlation coefficients between EKINPIX and loss ratios of 0.71 (0.79) for high (low) season storms and 0.76 (0.40) for mean damages of high (low) season hailstorms. Maximally possible loss ratios reach 60% (40%) in high (low) season storms with maximum mean damages of CHF 6000 (CHF 3000) and average values around CHF 3100 (CHF 2100). Seasonal differences in hailfall intensities are discussed in terms of atmospheric conditions favoring convective activity and the likelihood of higher numbers of large hailstones (>20 mm in diameter) that induce more severe damage to cars during the high storm season. The results suggest that radar-derived hail kinetic energy could be used by insurance companies in the future to (1) assess hail damage to cars immediately after a storm has passed over a radar observation area and (2) to estimate potential maximal hail losses to car portfolios for parts of central Europe.

  8. Doppler weather radar observations of the 2009 eruption of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Schneider, David J.; Hoblitt, Richard P.

    2013-01-01

    The U.S. Geological Survey (USGS) deployed a transportable Doppler C-band radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska that provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data captured during the Redoubt eruption. The MiniMax 250-C (MM-250C) radar detected seventeen of the nineteen largest explosive events between March 23 and April 4, 2009. Sixteen of these events reached the stratosphere (above 10 km) within 2–5 min of explosion onset. High column and proximal cloud reflectivity values (50 to 60 dBZ) were observed from many of these events, and were likely due to the formation of mm-sized accretionary tephra-ice pellets. Reflectivity data suggest that these pellets formed within the first few minutes of explosion onset. Rapid sedimentation of the mm-sized pellets was observed as a decrease in maximum detection cloud height. The volcanic cloud from the April 4 explosive event showed lower reflectivity values, due to finer particle sizes (related to dome collapse and related pyroclastic flows) and lack of significant pellet formation. Eruption durations determined by the radar were within a factor of two compared to seismic and pressure-sensor derived estimates, and were not well correlated. Ash dispersion observed by the radar was primarily in the upper troposphere below 10 km, but satellite observations indicate the presence of volcanogenic clouds in the stratosphere. This study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

  9. Doppler weather radar observations of the 2009 eruption of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Schneider, David J.; Hoblitt, Richard P.

    2013-06-01

    The U.S. Geological Survey (USGS) deployed a transportable Doppler C-band radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska that provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data captured during the Redoubt eruption. The MiniMax 250-C (MM-250C) radar detected seventeen of the nineteen largest explosive events between March 23 and April 4, 2009. Sixteen of these events reached the stratosphere (above 10 km) within 2-5 min of explosion onset. High column and proximal cloud reflectivity values (50 to 60 dBZ) were observed from many of these events, and were likely due to the formation of mm-sized accretionary tephra-ice pellets. Reflectivity data suggest that these pellets formed within the first few minutes of explosion onset. Rapid sedimentation of the mm-sized pellets was observed as a decrease in maximum detection cloud height. The volcanic cloud from the April 4 explosive event showed lower reflectivity values, due to finer particle sizes (related to dome collapse and related pyroclastic flows) and lack of significant pellet formation. Eruption durations determined by the radar were within a factor of two compared to seismic and pressure-sensor derived estimates, and were not well correlated. Ash dispersion observed by the radar was primarily in the upper troposphere below 10 km, but satellite observations indicate the presence of volcanogenic clouds in the stratosphere. This study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

  10. Analysis of daily rainfall of the Sahelian weather-station Linguère (Senegal) - Trends and its impacts on the local population

    NASA Astrophysics Data System (ADS)

    Strommer, Gabriel; Brandt, Martin; Diongue-Niang, Aida; Samimi, Cyrus

    2013-04-01

    In the 20th century, the West African Sahel has been a hot-spot of climatic changes. After severe drought-events in the 1970s and 1980s which were followed by a significant drop in annual precipitation, rainfall seems to increase again during the past years. Most studies are based on monthly or yearly datasets. However, many processes and events which are important for the local population depending on rainfall are not related to monthly or annual precipitation but are related to intra-annual, often daily scales. During this study, interviews with farmers and herders were conducted in the Senegalese Sahel. The results show, that wet months with unsuitably distributed precipitation can cause more harm than bringing benefits - depending on the phenological stage of the plants. Agricultural crops for example need rainfall breaks. On the other hand, natural herbaceous vegetation tolerates longer wet periods. So, a wet season can still hide dry spells that alter crops and vegetation development. Based on the results of these interviews, this study developed two indexes, one for local farmers and one for herders separately, showing if the year was favorable for them or not. The indexes integrate the length of rainy seasons, intensity and frequency of rainfall events, breaks between events and also the previous year. This way, each year is assigned to one of 5 classes. Using daily rainfall data of the Linguère weather-station (from the Senegal Meteorological Service, ANACIM), trends of the indexes from 1945 to 2002 are detected and compared to results of the interviews. Statistically relating the indexes to yearly and monthly data demonstrates, how much information can be gathered by those datasets. Furthermore, changes in intensity and frequency are related with yearly and monthly sums showing relations between daily data and annual sums. For example, a high correlation (r=0.73) between the amount of rain days (> 1 mm) and the annual rainfall is observed in Linguère.

  11. Time-dependent Second Order Scattering Theory for Weather Radar with a Finite Beam Width

    NASA Technical Reports Server (NTRS)

    Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood; Ito, Shigeo; Oguchi, Tomohiro

    2006-01-01

    Multiple scattering effects from spherical water particles of uniform diameter are studied for a W-band pulsed radar. The Gaussian transverse beam-profile and the rectangular pulse-duration are used for calculation. An second-order analytical solution is derived for a single layer structure, based on a time-dependent radiative transfer theory as described in the authors' companion paper. When the range resolution is fixed, increase in footprint radius leads to increase in the second order reflectivity that is defined as the ratio of the second order return to the first order one. This feature becomes more serious as the range increases. Since the spaceborne millimeter-wavelength radar has a large footprint radius that is competitive to the mean free path, the multiple scattering effect must be taken into account for analysis.

  12. The gust-front detection and wind-shift algorithms for the Terminal Doppler Weather Radar system

    NASA Technical Reports Server (NTRS)

    Hermes, Laurie G.; Witt, Arthur; Smith, Steven D.; Klingle-Wilson, Diana; Morris, Dale; Stumpf, Gregory J.; Eilts, Michael D.

    1993-01-01

    The Federal Aviation Administration's (FAA) Terminal Doppler Weather Radar (TDWR) system was primarily designed to address the operational needs of pilots in the avoidance of low-altitude wind shears upon takeoff and landing at airports. One of the primary methods of wind-shear detection for the TDWR system is the gust-front detection algorithm. The algorithm is designed to detect gust fronts that produce a wind-shear hazard and/or sustained wind shifts. It serves the hazard warning function by providing an estimate of the wind-speed gain for aircraft penetrating the gust front. The gust-front detection and wind-shift algorithms together serve a planning function by providing forecasted gust-front locations and estimates of the horizontal wind vector behind the front, respectively. This information is used by air traffic managers to determine arrival and departure runway configurations and aircraft movements to minimize the impact of wind shifts on airport capacity. This paper describes the gust-front detection and wind-shift algorithms to be fielded in the initial TDWR systems. Results of a quantitative performance evaluation using Doppler radar data collected during TDWR operational demonstrations at the Denver, Kansas City, and Orlando airports are presented. The algorithms were found to be operationally useful by the FAA airport controllers and supervisors.

  13. Automatic detection of low altitude wind shear due to gust fronts in the terminal Doppler weather radar operational demonstration

    NASA Technical Reports Server (NTRS)

    Klingle-Wilson, Diana

    1990-01-01

    A gust front is the leading edge of the cold air outflow from a thunderstorm. Wind shears and turbulence along the gust front may produce potentially hazardous conditions for an aircraft on takeoff or landing such that runway operations are significantly impacted. The Federal Aviation Administration (FAA) has therefore determined that the detection of gust fronts in the terminal environment be an integral part of the Terminal Doppler Weather Radar (TDWR) system. Detection of these shears by the Gust Front Algorithm permits the generation of warnings that can be issued to pilots on approach and departure. In addition to the detection capability, the algorithm provides an estimate of the wind speed and direction following the gust front (termed wind shift) and the forecasted location of the gust front up to 20 minutes before it impacts terminal operations. This has shown utility as a runway management tool, alerting runway supervisors to approaching wind shifts and the possible need to change runway configurations. The formation and characteristics of gust fronts and their signatures in Doppler radar data are discussed. A brief description of the algorithm and its products for use by Air Traffic Control (ATC), along with an assessment of the algorithm's performance during the 1988 Operational Test and Evaluation, is presented.

  14. Using X-band Weather Radar Measurements to Monitor the Integrity of Digital Elevation Models for Synthetic Vision Systems

    NASA Technical Reports Server (NTRS)

    Young, Steve; UijtdeHaag, Maarten; Sayre, Jonathon

    2003-01-01

    Synthetic Vision Systems (SVS) provide pilots with displays of stored geo-spatial data representing terrain, obstacles, and cultural features. As comprehensive validation is impractical, these databases typically have no quantifiable level of integrity. Further, updates to the databases may not be provided as changes occur. These issues limit the certification level and constrain the operational context of SVS for civil aviation. Previous work demonstrated the feasibility of using a realtime monitor to bound the integrity of Digital Elevation Models (DEMs) by using radar altimeter measurements during flight. This paper describes an extension of this concept to include X-band Weather Radar (WxR) measurements. This enables the monitor to detect additional classes of DEM errors and to reduce the exposure time associated with integrity threats. Feature extraction techniques are used along with a statistical assessment of similarity measures between the sensed and stored features that are detected. Recent flight-testing in the area around the Juneau, Alaska Airport (JNU) has resulted in a comprehensive set of sensor data that is being used to assess the feasibility of the proposed monitor technology. Initial results of this assessment are presented.

  15. Landslide occurrences and recurrence intervals of heavy rainfalls in Japan

    NASA Astrophysics Data System (ADS)

    Saito, H.; Uchida, T.; Matsuyama, H.; Korup, O.

    2015-12-01

    Dealing with predicted increases in extreme weather conditions due to climate change requires robust knowledge about controls on rainfall-triggered landslides. This study developed the probable rainfall database from weather radar data, and analyzed the potential correlation between the landslide magnitude-frequency and the recurrence interval of the heavy rainfall across Japan. We analyzed 4,744 rainfall-induced landslides (Saito et al., 2014, Geology), 1 to 72 h rainfalls, and soil water index (SWI). We then estimated recurrence intervals for these rainfall parameters using a Gumbel distribution with jackknife fitting. Results showed that the recurrence intervals of rainfall events which caused landslides (<10^3 m^3) were less than 10 yr across Japan. The recurrence intervals increased with increases in landslide volumes. With regard to the landslides larger than 10^5 m^3, recurrence intervals of the rainfall events were more than 100 yr. These results suggest that recurrence intervals of heavy rainfalls are important for assessing regional landslide hazard in Japan.

  16. Atmosphere-Truth Z-R Rainfall Estimates: A Fresh Approach to an Old Problem

    NASA Astrophysics Data System (ADS)

    Henz, J. F.

    2010-12-01

    Common modeling practice for basin calibration uses rainfall fields developed by the statistical use of surface rain gauge observed data or the direct application of NEXRAD National Weather Service WSR-88D Doppler radar Storm Total Rainfall or 1-hr rainfall estimations. Each of these approaches has significant limitations. Rain gages often lack sufficient spatial coverage to measure true storm intensity or the distribution of rainfall in a basin. The NWS WSR-88D Doppler radar algorithms are constantly being improved but still fail to deliver consistent rainfall estimates. Significant problems are caused by an under-estimation of warm coalescence rains and an over-estimation of rainfall in both dry environments and storms with hail contamination. Finally, storm updraft areas are frequently counted as raining portions of the storm producing immediate errors. The statistical techniques often under-estimate rainfall when the heavy rain core of the storm misses the rain gauges or if high winds cause an under-catchment of rainfall. Gauge-adjusted rainfall estimates are also dependant on the core of the storm being observed by a gauge. Statistical approaches often under-estimate rainfall producing insufficient runoff to drive the observed flooding runoffs. The Atmosphere-Truth ZR (ATZR) technique uses an atmosphere-truthed algorithm to produce highly accurate estimates of surface rainfall from Doppler radar data. This approach relies on using a cloud physics approach to determine the atmosphere’s ability to produce 15-min to hourly rain rates. The atmsopheric rainfall is utilizes surface, boundary layer and cloud layer observations of temperature and moisture from conventional National Weather Service observations. The depth of the thunderstorm updraft region that exceeds 0C is used with the precipitable water index and updraft speeds to provide estimates of 15-min to hourly rainfall rates from radar reflectivity areas in the storm greather than 50 dBZ. Rainfall rates

  17. Short-term risk forecasts of heavy rainfall.

    PubMed

    Schmid, W; Mecklenburg, S; Joss, J

    2002-01-01

    Methodologies for risk forecasts of severe weather hardly exist on the scale of nowcasting (0-3 hours). Here we discuss short-term risk forecasts of heavy precipitation associated with local thunderstorms. We use COTREC/RainCast: a procedure to extrapolate radar images into the near future. An error density function is defined using the estimated error of location of the extrapolated radar patterns. The radar forecast is folded ("smeared") with the density function, leading to a probability distribution of radar intensities. An algorithm to convert the radar intensities into values of precipitation intensity provides the desired probability (or risk) of heavy rainfall at any position within the considered window in space and time. We discuss, as an example, a flood event from summer 2000.

  18. Analysis of Performance Characteristics of the MWR-05XP Mobile Weather Radar

    DTIC Science & Technology

    2005-12-31

    RCS in cm2 Aphid 10-5 Mosquito 5x10-4 Ladybug 10-2 Moth 1.0 Sparrow 1.6 Grackle 16 Table 1. X-band radar cross-sections for some birds and...6). The result is shown in Figure 8. The range of RCS in Figure 8 is 10-5 cm2 to 10 cm2; the smallest RCS value corresponding to an aphid and...level and is not MWR-05XP Single Pulse Bird & Insect Return: RX Power in dBm vs. Range in Kilometers RCS Parameter -50 dBscm ( Aphid ) to +10 dBscm

  19. Nexrad-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    NASA Astrophysics Data System (ADS)

    Im, E.; Chandrasekar, V.; Chen, S. S.; Holland, G. J.; Kakar, R.; Lewis, W. E.; Marks, F. D.; Smith, E. A.; Tanelli, S.; Tripoli, G. J.

    2007-12-01

    The Nexrad-In-Space (NIS) is a revolutionary atmospheric radar observation concept from the geostationary orbiting platform. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS radar would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with a 12-km horizontal resolution, and a minimum detectable signal of 5 dBZ. The NIS radar achieves its superb sampling capabilities by use of a 35-m diameter, deployable antenna made from lightweight membrane material. The antenna has two transmit-receive array pairs that create a dual-beam, spiral-feed combined profile image of both reflectivity and Doppler velocity approximately every 60 minutes. This sampling time can be shortened even further by increasing the number of transmit-receive array pairs. It is generally recognized that the processes important in governing hurricane intensity and structure span a wide range of spatial and temporal scales. The environmental forcing considerations require a large domain. The vortex response to the environmental forcing ultimately involves convection on small horizontal scales in the eyewall and rainband regions. Resolving this environment-vortex-convection feedback in a numerical model requires observations on the space and time scales necessary to unambiguously define these structures within and surrounding the tropical cyclone. Because the time and space scales of these processes are small, continuous 3-dimensional independent observations of the 3-dimensional wind and precipitation structures will be needed to initialize numerical models critical for this purpose. The proposed NIS Doppler radar would be the first instrument capable of accomplishing this feat at time scales less than hours, and would create the opportunity for hurricane science to enter a new era of understanding and improved prediction. This

  20. Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational Evaluation Testing

    DTIC Science & Technology

    1990-08-17

    significant changes to the SP this year. The dual DAA ( DDAA ) configuration of 1988 was used for the bulk of this year’s data gathering, and a new DAA (NDAA...numerical truncation in factor values from the DDAA . Using input data from a simulated radar source, it was found that the DDAA frequently produced...34speckles" occurred frequently in the data displays when the DDAA was used, and to a much lesser extent with the NDAA. These effects have been reduced but

  1. Enhanced Orographic Tropical Rainfall: An Study of the Colombia's rainfall

    NASA Astrophysics Data System (ADS)

    Peñaranda, V. M.; Hoyos Ortiz, C. D.; Mesa, O. J.

    2015-12-01

    Convection in tropical regions may be enhanced by orographic barriers. The orographic enhancement is an intensification of rain rates caused by the forced lifting of air over a mountainous structure. Orographic heavy rainfall events, occasionally, comes along by flooding, debris flow and substantial amount of looses, either economics or human lives. Most of the heavy convective rainfall events, occurred in Colombia, have left a lot of victims and material damages by flash flooding. An urgent action is required by either scientific communities or society, helping to find preventive solutions against these kind of events. Various scientific literature reports address the feedback process between the convection and the local orographic structures. The orographic enhancement could arise by several physical mechanism: precipitation transport on leeward side, convection triggered by the forcing of air over topography, the seeder-feeder mechanism, among others. The identification of the physical mechanisms for orographic enhancement of rainfall has not been studied over Colombia. As far as we know, orographic convective tropical rainfall is just the main factor for the altitudinal belt of maximum precipitation, but the lack of detailed hydro-meteorological measurements have precluded a complete understanding of the tropical rainfall in Colombia and its complex terrain. The emergence of the multifractal theory for rainfall has opened a field of research which builds a framework for parsimonious modeling of physical process. Studies about the scaling behavior of orographic rainfall have found some modulating functions between the rainfall intensity probability distribution and the terrain elevation. The overall objective is to advance in the understanding of the orographic influence over the Colombian tropical rainfall based on observations and scaling-analysis techniques. We use rainfall maps, weather radars scans and ground-based rainfall data. The research strategy is

  2. A high-resolution rainfall re-analysis based on radar-raingauge merging in the Cévennes-Vivarais region, France

    NASA Astrophysics Data System (ADS)

    Boudevillain, Brice; Delrieu, Guy; Wijbrans, Annette; Confoland, Audrey

    2016-10-01

    This work aims at providing quantitative precipitation estimates (QPEs) for the Cévennes-Vivarais region, France, over temporal (1-6 h) and spatial (1-300 km2) scales relevant for flash-flood prediction in that region. A systematic implementation of three estimation methods (radar QPE, hourly raingauge Ordinary Kriging - OK - and merging of radar and raingauge data through Kriging with External Drift - KED) proves the KED method to systematically outperform the concurrent approaches for the 131 main rain events selected during the period 2007-2014. Error models, assuming the standard deviation of the QPE error to be a bi-linear function of the rain rate and the kriging normalized estimation standard deviation, are parameterized for the KED and OK QPEs for the considered temporal and spatial scales. The error models are shown to depend on the type of rain event (Cévennes rain events, localized convection, widespread rainfall) and physical parameters such as the 0 °C isotherm altitude and the rain intermittency. The added-value of the radar network in terms of QPE with respect to the hourly raingauge network is larger for localized convection rain events as well as for the smallest space-time scales which are those of interest for flash-flood prediction in the region.

  3. High-resolution summer rainfall prediction in the JHWC real-time WRF system

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Kyou; Eom, Dae-Yong; Kim, Joo-Wan; Lee, Jae-Bok

    2010-08-01

    The WRF-based real-time forecast system (http://jhwc.snu.ac.kr/weather) of the Joint Center for High-impact Weather and Climate Research (JHWC) has been in operation since November 2006; this system has three nested model domains using GFS (Global Forecast System) data for its initial and boundary conditions. In this study, we evaluate the improvement in daily and hourly weather prediction, particularly the prediction of summer rainfall over the Korean Peninsula, in the JHWC WRF (Weather Research and Forecasting) model system by 3DVAR (three-Dimensional Variational) data assimilation using the data obtained from KEOP (Korea Enhanced Observation Program). KEOP was conducted during the period June 15 to July 15, 2007, and the data obtained included GTS (Global Telecommunication System) upper-air sounding, AWS (Automatic Weather System), wind profiler, and radar observation data. Rainfall prediction and its characteristics should be verified by using the precipitation observation and the difference field of each experiment. High-resolution (3 km in domain 3) summer rainfall prediction over the Korean peninsula is substantially influenced by improved synoptic-scale prediction in domains 1 (27 km) and 2 (9 km), in particular by data assimilation using the sounding and wind profiler data. The rainfall prediction in domain 3 was further improved by radar and AWS data assimilation in domain 3. The equitable threat score and bias score of the rainfall predicted in domain 3 indicated improvement for the threshold values of 0.1, 1, and 2.5 mm with data assimilation. For cases of occurrence of heavy rainfall (7 days), the equitable threat score and bias score improved considerably at all threshold values as compared to the entire period of KEOP. Radar and AWS data assimilation improved the temporal and spatial distributions of diurnal rainfall over southern Korea, and AWS data assimilation increased the predicted rainfall amount by approximately 0.3 mm 3hr-1.

  4. Estimating particle sizes, concentrations, and total mass of ash in volcanic clouds using weather radar

    NASA Astrophysics Data System (ADS)

    Harris, D. M.; Rose, W. I., Jr.

    1983-12-01

    Radar observations of the March 19, 1982 ash eruption of Mount St. Helens were used to estimate the volume of the ash cloud (2000 + or - 500 cu km), the concentration of ash (0.2-0.6 g/cu m), and the total mass of ash erupted (3-10 x 10 to the 11th g). Previously published ashfall data for the May 18, 1980 Mount St. Helens eruption were studied using an inversion technique to estimate 6-hr mean particle concentration (3 g/cu m), the size distribution, the total ashfall mass (5 x 10 to the 14th g), and radar reflectivity factors for the ash cloud. Because volcanic ash clouds with particle concentrations of at least 0.2 g/cu m are produced in very small (in terms of total ashfall mass) eruptions of duration less than 1 min, volcanic ash clouds must be considered an extremely serious hazard to in-flight aircraft, regardless of the eruption magnitude.

  5. Validating NEXRAD MPE and Stage III precipitation products for uniform rainfall on the Upper Guadalupe River Basin of the Texas Hill Country

    NASA Astrophysics Data System (ADS)

    Wang, Xianwei; Xie, Hongjie; Sharif, Hatim; Zeitler, Jon

    2008-01-01

    SummaryThis study examines the performance of the Next Generation Weather Radar (NEXRAD) Multisensor Precipitation Estimator (MPE) and Stage III precipitation products, using a high-density rain gauge network located on the Upper Guadalupe River Basin of the Texas Hill Country. As point-area representativeness error of gauge rainfall is a major concern in assessment of radar rainfall estimation, this study develops a new method to automatically select uniform rainfall events based on coefficient of variation criterion of 3 by 3 radar cells. Only gauge observations of those uniform rainfall events are used as ground truth to evaluate radar rainfall estimation. This study proposes a new parameter probability of rain detection (POD) instead of the conditional probability of rain detection (CPOD) commonly used in previous studies to assess the capability that a radar or gauge detects rainfall. Results suggest that: (1) gauge observations of uniform rainfall better represent ground truth of a 4 × 4 km 2 radar cell than non-uniform rainfall; (2) the MPE has higher capability of rain detection than either gauge-only or Stage III; (3) the MPE has much higher linear correlation and lower mean relative difference with gauge measurements than the Stage III does; (4) the Stage III tends to overestimate precipitation (20%), but the MPE tends to underestimate (7%).

  6. Weak Linkage between the Heaviest Rainfall and Tallest Storms

    NASA Astrophysics Data System (ADS)

    Hamada, A.; Takayabu, Y. N.; Liu, C.; Zipser, E. J.

    2015-12-01

    Eleven years measurements from the Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite reveals robust differences in rainfall characteristics between extreme rainfall and convection events, irrespective of region. After accumulating `rainfall events' defined as a set of contiguous rainy pixels of TRMM PR measurements for each 2.5 x 2.5 degree grid cell, three different types of regional extreme rainfall events are defined in each grid cell, using the maximum values of near-surface rainfall rate (NSR) and 40-dBZ echo top height (ETH40) in rainfall events; R-only (H-only) extreme events are defined as rainfall events of which the maximum NSR (ETH40) is within top 0.1% but the ETH40 (NSR) is not; RH extreme events are defined as those of which both the maxima of NSR and ETH40 are within top 0.1%. Only a small fraction of rainfall extreme events are found to be related to convective extremes. The results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. There are robust differences in echo profiles, rainfall characteristics, and local environments between extreme rainfall and convection events, irrespective of region. Extreme rainfall events exhibit lower echo-top height and downward increase of radar reflectivity (Ze) below the freezing level, whereas extreme convection events exhibit more vertically aligned echo structure. The echo and environmental characteristics of extreme rainfall events imply the importance of warm-rain processes in producing extreme rainfall. An important concern regarding the PR measurements in Ku band is significant attenuation by severe hailstorms. We performed a statistical evaluation of the PR measurements using 5-yr measurements obtained during the Baiu season (May-June) using a ground-based C-band radar in Okinawa, Japan, and confirmed that the attenuation

  7. Inter-Comparison of CHARM Data and WSR-88D Storm Integrated Rainfall

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary J.; Meyer, Paul J.; Guillory, Anthony R.; Stellman, Keith; Limaye, Ashutosh; Arnold, James E. (Technical Monitor)

    2002-01-01

    A localized precipitation network has been established over a 4000 sq km region of northern Alabama in support of local weather and climate research at the Global Hydrology and Climate Center (GHCC) in Huntsville. This Cooperative Huntsville-Area Rainfall Measurement (CHARM) network is comprised of over 80 volunteers who manually take daily rainfall measurements from 85 sites. The network also incorporates 20 automated gauges that report data at 1-5 minute intervals on a 24 h a day basis. The average spacing of the gauges in the network is about 6 kin, however coverage in some regions benefit from gauges every 1-2 km. The 24 h rainfall totals from the CHARM network have been used to validate Stage III rainfall estimates of daily and storm totals derived from the WSR-88D radars that cover northern Alabama. The Stage III rainfall product is produced by the Lower Mississippi River Forecast Center (LMRFC) in support of their daily forecast operations. The intercomparisons between the local rain gauge and the radar estimates have been useful to understand the accuracy and utility of the Stage III data. Recently, the Stage III and CHARM rainfall measurements have been combined to produce an hourly rainfall dataset at each CHARM observation site. The procedure matches each CHARM site with a time sequence of Stage III radar estimates of precipitation. Hourly stage III rainfall estimates were used to partition the rain gauge values to the time interval over which they occurred. The new hourly rain gauge dataset is validated at selected points where 1-5 minute rainfall measurements have been made. This procedure greatly enhances the utility of the CHARM data for local weather and hydrologic modeling studies. The conference paper will present highlights of the Stage III intercomparison and some examples of the combined radar / rain gauge product demonstrating its accuracy and utility in deriving an hourly rainfall product from the 24 h CHARM totals.

  8. Ground validation of Dual Precipitation Radar (DPR) on GPM by rapid scan Phased Array weahter Radar (PAR)

    NASA Astrophysics Data System (ADS)

    Hirano, Y.; Mega, T.; Shimamura, S.; Wu, T.; Kikuchi, H.; Ushio, T.; Yoshikawa, E.; Chandra, C. V.

    2014-12-01

    The core observatory satellite of the Global Precipitation Measurement (GPM) mission was launched on February 27th 2014. The Dual-frequency Precipitation Radar (DPR) on the GPM core observatory is the succession of the TRMM Precipitation Radar (PR). The DPR consists of a Ku-band precipitation radar and a Ka-band precipitation radar. The DPR is expected to be more sensitive than the PR especially in the measurement of light rainfall and snowfall in high latitude regions. Because of the difference of spatial and temporal resolutions, Space Radar (SR) and conventional type of Ground Radar (GR) are hard to compare.The SR observes each point of earth in short time, for example one footprint is an observation in some microseconds. Rain-gauge measurements have accurate rainfall rate, but rain-gage observes small area and accumulated rainfall in some minutes. The conventional GR can cover a wide area, however, a volume scan requires several minutes. The Phased Array weather Radar (PAR) is developed by Osaka University, Toshiba, and NICT. The PAR is a weather-radar on X-band within 100m range sampling. High spatial and temporal resolution is achieved by the PAR with pulse compression and the digital beam-forming technique. The PAR transmits a wide beam and receives narrow beams by using digital beam forming. Then, the PAR observes many elevation angles from a single pulse. The time of each volume scan is 10-30 seconds in operation, typically 30 seconds. The study shows comparisons between the DPR and the PAR by more similar spatial and temporal resolution. The rainfall region of DPR is similar to the one of PAR. Correlation coefficient of both radar reflectivity suggests more than 0.8 in the 20km range of PAR. As a result, it is considered that DPR can observe with high accuracy. We present the case study which DPR overpassed the PAR observation region in detail.

  9. A simple simulation approach to generate complex rainfall fields conditioned by elevation: example of the eastern Mediterranean region

    NASA Astrophysics Data System (ADS)

    Oriani, Fabio; Ohana-Levi, Noa; Straubhaar, Julien; Renard, Philippe; Karnieli, Arnon; Mariethoz, Grégoire; Morin, Efrat; Marra, Francesco

    2016-04-01

    Stochastically generating realistic rainfall fields is useful to study the uncertainty related to catchment recharge and its propagation to distributed hydrological models. To this end, it is critical to use weather radar images as training data, being the single most informative source for rainfall spatial heterogeneity. Generating realistic simulations is particularly important in regions like the eastern Mediterranean, where the synoptic conditions can lead to rainfall fields presenting various morphology, anisotropy and non-stationarity. The Direct Sampling (DS) technique [Mariethoz2010] is proposed here as a stochastic generator of spatial daily rainfall fields relying on the simulation of radar imagery. The technique is based on resampling of a training data set (in this case, a stack of radar images) and the generation of similar patterns to the ones found in the data. The strong point of DS, which makes it an attractive simulation approach for rainfall, is its capability to preserve the high-order statistical features present in the training image (e.g., rainfall cell shape, spatial non-stationarity) with minimal parameterization. Moreover, factors influencing rainfall, like elevation, can be used as conditioning variables, without the need of a complex statistical dependence model. A DS setup for radar image simulation is presented and tested for the simulation of daily rainfall fields using a 10-year radar-image record from the central region of Israel. Using a synoptic weather classification to train the model, the algorithm can generate realistic spatial fields for different rainfall types, preserving the variability and the covariance structure of the reference reasonably well. Moreover, the simulation is conditioned using the digital elevation model to preserve the complex relation between rainfall intensity and altitude that is characteristic for this region. [Mariethoz2010] G. Mariethoz, P. Renard, and J. Straubhaar. The direct sampling method to

  10. Runoff simulation using radar and rain gauge data

    NASA Astrophysics Data System (ADS)

    Liu, X. Y.; Mao, J. T.; Zhu, Y. J.; Li, J. R.

    2003-03-01

    The conceptual rainfall-runoff model TOPMODEL is used to simulate runoffs of the Meishan and Nianyushan catchments during the summers of 1998 and 1999 in the GAME/HUBEX (GEWEX Asia Monsoon Experiment /HUAIHE River Basin Experiment) project. The rainfall distributions are estimated by weather radar and rain gauge networks according to different methods. Observed and simulated runoffs are compared and analyzed for both catchments. Results show that (1) the runoff of the catchment is best simulated by radar data combined with rain gauge network data from inside the catchment, and (2) the rainfall estimated by radar adjusted by a few rain gauges outside the catchment can be used to simulate runoff equally as well as using the dense rain gauge network alone.

  11. Designing clutter rejection filters with complex coefficients for airborne pulsed Doppler weather radar

    NASA Technical Reports Server (NTRS)

    Jamora, Dennis A.

    1993-01-01

    Ground clutter interference is a major problem for airborne pulse Doppler radar operating at low altitudes in a look-down mode. With Doppler zero set at the aircraft ground speed, ground clutter rejection filtering is typically accomplished using a high-pass filter with real valued coefficients and a stopband notch centered at zero Doppler. Clutter spectra from the NASA Wind Shear Flight Experiments of l991-1992 show that the dominant clutter mode can be located away from zero Doppler, particularly at short ranges dominated by sidelobe returns. Use of digital notch filters with complex valued coefficients so that the stopband notch can be located at any Doppler frequency is investigated. Several clutter mode tracking algorithms are considered to estimate the Doppler frequency location of the dominant clutter mode. From the examination of night data, when a dominant clutter mode away from zero Doppler is present, complex filtering is able to significantly increase clutter rejection over use of a notch filter centered at zero Doppler.

  12. 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)

    Ihara, Toshio; Nakamura, Kenji

    1988-07-01

    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.

  13. Second-order multiple-scattering theory associated with backscattering enhancement for a millimeter wavelength weather radar with a finite beam width

    NASA Technical Reports Server (NTRS)

    Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood

    2005-01-01

    Effects of multiple scattering on reflectivity are studied for millimeter wavelength weather radars. A time-independent vector theory, including up to second-order scattering, is derived for a single layer of hydrometeors of a uniform density and a uniform diameter. In this theory, spherical waves with a Gaussian antenna pattern are used to calculate ladder and cross terms in the analytical scattering theory. The former terms represent the conventional multiple scattering, while the latter terms cause backscattering enhancement in both the copolarized and cross-polarized components. As the optical thickness of the hydrometeor layer increases, the differences from the conventional plane wave theory become more significant, and essentially, the reflectivity of multiple scattering depends on the ratio of mean free path to radar footprint radius. These results must be taken into account when analyzing radar reflectivity for use in remote sensing.

  14. ASR-9 Weather Channel Test Report.

    DTIC Science & Technology

    1989-05-03

    C - Band Pencil-Beam Radar System Overview... radar data, Lincoln Laboratory con- tracted with the MIT Weather Radar Laboratory of the EAPS to operate a C - band Doppler weather radar and record volume...features of the C - Band pencil beam radar were expected to produce occa- sional discrepancies relative to the ASR-9 and FL-3 data. The C - Band radar

  15. Military Hydrology: Report 18, State-of-the-Art Review and Annotated Bibliography of Radar-Rain Gage Relations and Short-Term Weather Forecasting

    DTIC Science & Technology

    1991-04-01

    RADAR-RAIN GAGE RELATIONS AND SHORT-TERM WEATHER FORECASTING by Willard R. McDaniel East Texas State University Commerce , Texas 75428 ~DTTC April 1991...ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER East Texas State University, Commerce , TX 75428 9. SPONSORING/ MONITORING... Commerce , TX. At the time, Dr. McDaniel was with the US Army Summer Faculty Research and Engineering Program working under contract No. DAGG29-8 I-D

  16. Airborne derivation of microburst alerts from ground-based Terminal Doppler Weather Radar information: A flight evaluation

    NASA Technical Reports Server (NTRS)

    Hinton, David A.

    1993-01-01

    An element of the NASA/FAA windshear program is the integration of ground-based microburst information on the flight deck, to support airborne windshear alerting and microburst avoidance. NASA conducted a windshear flight test program in the summer of 1991 during which airborne processing of Terminal Doppler Weather Radar (TDWR) data was used to derive microburst alerts. Microburst information was extracted from TDWR, transmitted to a NASA Boeing 737 in flight via data link, and processed to estimate the windshear hazard level (F-factor) that would be experienced by the aircraft in each microburst. The microburst location and F-factor were used to derive a situation display and alerts. The situation display was successfully used to maneuver the aircraft for microburst penetrations, during which atmospheric 'truth' measurements were made. A total of 19 penetrations were made of TDWR-reported microburst locations, resulting in 18 airborne microburst alerts from the TDWR data and two microburst alerts from the airborne reactive windshear detection system. The primary factors affecting alerting performance were spatial offset of the flight path from the region of strongest shear, differences in TDWR measurement altitude and airplane penetration altitude, and variations in microburst outflow profiles. Predicted and measured F-factors agreed well in penetrations near microburst cores. Although improvements in airborne and ground processing of the TDWR measurements would be required to support an airborne executive-level alerting protocol, the practicality of airborne utilization of TDWR data link data has been demonstrated.

  17. Retrieval algorithm for rainfall mapping from microwave links in a cellular communication network

    NASA Astrophysics Data System (ADS)

    Overeem, A.; Leijnse, H.; Uijlenhoet, R.

    2015-08-01

    Microwave links in commercial cellular communication networks hold a promise for areal rainfall monitoring and could complement rainfall estimates from ground-based weather radars, rain gauges, and satellites. It has been shown that country-wide rainfall maps can be derived from the signal attenuations of microwave links in such a network. Here we give a detailed description of the employed rainfall retrieval algorithm and provide the corresponding code. Moreover, the code (in the scripting language "R") is made available including a data set of commercial microwave links. The purpose of this paper is to promote rainfall monitoring utilizing microwave links from cellular communication networks as an alternative or complementary means for global, continental-scale rainfall monitoring.

  18. Retrieval algorithm for rainfall mapping from microwave links in a cellular communication network

    NASA Astrophysics Data System (ADS)

    Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko

    2016-06-01

    Microwave links in commercial cellular communication networks hold a promise for areal rainfall monitoring and could complement rainfall estimates from ground-based weather radars, rain gauges, and satellites. It has been shown that country-wide (≈ 35 500 km2) 15 min rainfall maps can be derived from the signal attenuations of approximately 2400 microwave links in such a network. Here we give a detailed description of the employed rainfall retrieval algorithm. Moreover, the documented, modular, and user-friendly code (a package in the scripting language "R") is made available, including a 2-day data set of approximately 2600 commercial microwave links from the Netherlands. The purpose of this paper is to promote rainfall mapping utilising microwave links from cellular communication networks as an alternative or complementary means for continental-scale rainfall monitoring.

  19. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  1. Sources of Uncertainty in Rainfall Maps from Cellular Communication Networks

    NASA Astrophysics Data System (ADS)

    Rios Gaona, Manuel Felipe; Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko

    2015-04-01

    Accurate measurements of rainfall are important in many hydrological applications, for instance, flash-flood early-warning systems, hydraulic structures design, agriculture, weather forecasting, and climate modelling. Rainfall intensities can be retrieved from (commercial) microwave link networks. Whenever possible, link networks measure and store the decrease in power of the electromagnetic signal at regular intervals. The decrease in power is largely due to the attenuation by raindrops along the link paths. Such an alternative technique fulfills the continuous strive for measurements of rainfall in time and space at higher resolutions, especially in places where traditional rain gauge networks are scarce or poorly maintained. Rainfall maps from microwave link networks have recently been introduced at country-wide scales. Despite their potential in rainfall estimation at high spatiotemporal resolutions, the uncertainties present in rainfall maps from link networks are not yet fully comprehended. The aim of this work is to identify and quantify the sources of uncertainty present in interpolated rainfall maps from link rainfall depths. In order to disentangle these sources of uncertainty, we classified them into two categories: (1) those associated with the individual microwave link measurements, i.e., the physics involved in the measurements such as wet antenna attenuation, sampling interval of measurements, wet/dry period classification, drop size distribution (DSD), and multi-path propagation; (2) those associated with mapping, i.e., the combined effect of the interpolation methodology, the spatial density of the network, and the availability of link measurements. We computed ~ 3500 rainfall maps from real and simulated link rainfall depths for 12 days for the land surface of The Netherlands. These rainfall maps were compared against quality-controlled gauge-adjusted radar rainfall fields (assumed to be the ground truth). Thus, we were able to not only identify

  2. Spatio-Temporal Description of the Rainfall for Colombian Andean Mountainous Region for Weather Forecasting Purposes. Case Study: Manizales - Caldas, Colombia

    NASA Astrophysics Data System (ADS)

    Suarez Hincapie, J. N.

    2014-12-01

    Manizales is a city located in west-central Colombian Andes in the Caldas province, whose spatial location coincides with one of the most threatened areas of Colombia (landslides, earthquakes, volcanic eruptions, other). As a middle Andean mountainous city and for being located in the area of influence of the ITCZ presents an equatorial mountain climate with a bimodal rainfall regime, and with an average annual rainfall around 2000 mm, it shows very significant rates of precipitation, on average, 70% of the days of the year it is rainy. This situation favors the formation of large masses of clouds and the presence of macroclimatic phenomena such as ENSO, which has historically caused large-scale impacts in both warm and cold phase. Since last decade different entities have implemented a hydro-meteorological network which measures and transmits telemetrically every five minutes hydro-climatic variables. In general, the real-time weather monitoring should be used for a better understanding of our environmental urban environment and to establish indicators of quality of life and welfare for the community. Despite the city has telemetric data on atmospheric and hydrological variables, there is still no tool or a methodology able to generate a spatio-temporal description of these variables. So, the aim of this work is to establish guidelines to sort all this information of atmospheric variables monitored in real time with the help of data mining techniques, machine learning tools to improve the knowledge of atmospheric patterns at Manizales and to serve for territorial planning and decision makers. To reach this purpose the current data warehouse available at the National University of Colombia at Manizales will be used, and it will be fed with observed variables from hydro-meteorological monitoring stations that transmit in real-time. Then, as mentioned this information will make the corresponding processing with data mining techniques to describe the rainfall patterns

  3. Static and dynamic calibration of radar data for hydrological use

    NASA Astrophysics Data System (ADS)

    Wood, S. J.; Jones, D. A.; Moore, R. J.

    The HYREX dense raingauge network over the Brue catchment in Somerset, England is used to explore the accuracy of calibrated (raingauge-adjusted) weather radar data. Calibration is restricted to the use of any single gauge within the catchment so as to simulate the conditions in a typical rainfall monitoring network. Combination of a single gauge and a radar estimate is used to obtain calibrated radar estimates, with the "calibration factor" varying dynamically from one time-frame to the next. Comparing this dynamic calibration with a static (long-term) calibration factor indicates the distance from a gauge over which the dynamic calibration is useful. A tapered calibration factor is implemented which behaves in the same way as the raw dynamic calibration at short distances, tending towards the static calibration factor at larger distances. This hybrid approach outperforms raingauge, uncalibrated radar, and statically-calibrated radar estimates of rainfall for the majority of raingauges in the catchment. The results provide valuable guidance on the density of raingauge network to employ in combination with a weather radar for flood estimation and forecasting.

  4. Countrywide rainfall maps from a commercial cellular telecommunication network

    NASA Astrophysics Data System (ADS)

    Overeem, A.; Leijnse, H.; Uijlenhoet, R.

    2012-12-01

    Accurate rainfall observations with high spatial and temporal resolutions are needed for hydrological applications, agriculture, meteorology, and climate monitoring. However, the majority of the land surface of the earth lacks accurate rainfall information. Many countries do not have continuously operating weather radars, and have no or few rain gauges. A new development is rainfall estimation from microwave links of commercial cellular telecommunication networks. Such networks cover large parts of the land surface of the earth and have a high density, especially in urban areas. The estimation of rainfall using commercial microwave links could therefore become a valuable source of information. The data produced by microwave links is essentially a by-product of the communication between mobile telephones. Rainfall attenuates the electromagnetic signals transmitted from one telephone tower to another. By measuring the received power at one end of a microwave link as a function of time, the path-integrated attenuation due to rainfall can be calculated. Previous studies have shown that average rainfall intensities over the length of a link can be derived from the path-integrated attenuation. A dataset from a commercial microwave link network over the Netherlands is analyzed, containing data from an unprecedented number of links (1500) covering the land surface of the Netherlands (35500 km2). This dataset consists of 24 days with substantial rainfall in June - September 2011. A rainfall retrieval algorithm is presented to derive rainfall intensities from the microwave link data, which have a temporal resolution of 15 min. Rainfall maps (1 km spatial resolution) are generated from these rainfall intensities using Kriging. This algorithm is suited for real-time application, and is calibrated on a subset (12 days) of the dataset. The other 12 days in the dataset are used to validate the algorithm. Both calibration and validation are done using gauge-adjusted radar data

  5. Sources of uncertainty in rainfall maps from cellular communication networks

    NASA Astrophysics Data System (ADS)

    Rios Gaona, M. F.; Overeem, A.; Leijnse, H.; Uijlenhoet, R.

    2015-03-01

    Accurate measurements of rainfall are important in many hydrological and meteorological applications, for instance, flash-flood early-warning systems, hydraulic structures design, irrigation, weather forecasting, and climate modelling. Whenever possible, link networks measure and store the received power of the electromagnetic signal at regular intervals. The decrease in power can be converted to rainfall intensity, and is largely due to the attenuation by raindrops along the link paths. Such alternative technique fulfills the continuous strive for measurements of rainfall in time and space at higher resolutions, especially in places where traditional rain gauge networks are scarce or poorly maintained. Rainfall maps from microwave link networks have recently been introduced at country-wide scales. Despite their potential in rainfall estimation at high spatiotemporal resolutions, the uncertainties present in rainfall maps from link networks are not yet fully comprehended. The aim of this work is to identify and quantify the sources of uncertainty present in interpolated rainfall maps from link rainfall depths. In order to disentangle these sources of uncertainty, we classified them into two categories: (1) those associated with the individual microwave link measurements, i.e., the errors involved in single-link rainfall retrievals such as wet antenna attenuation, sampling interval of measurements, wet/dry period classification, quantization of the received power, drop size distribution (DSD), and multi-path propagation; (2) those associated with mapping, i.e., the combined effect of the interpolation methodology and the spatial density of link measurements. We computed ~3500 rainfall maps from real and simulated link rainfall depths for 12 days for the land surface of the Netherlands. Simulated link rainfall depths were obtained from radar data. These rainfall maps were compared against quality-controlled gauge-adjusted radar rainfall fields (assumed to be the

  6. Road Weather and Connected Vehicles

    NASA Astrophysics Data System (ADS)

    Pisano, P.; Boyce, B. C.

    2015-12-01

    On average, there are over 5.8 M vehicle crashes each year of which 23% are weather-related. Weather-related crashes are defined as those crashes that occur in adverse weather or on slick pavement. The vast majority of weather-related crashes happen on wet pavement (74%) and during rainfall (46%). Connected vehicle technologies hold the promise to transform road-weather management by providing improved road weather data in real time with greater temporal and geographic accuracy. This will dramatically expand the amount of data that can be used to assess, forecast, and address the impacts that weather has on roads, vehicles, and travelers. The use of vehicle-based measurements of the road and surrounding atmosphere with other, more traditional weather data sources, and create road and atmospheric hazard products for a variety of users. The broad availability of road weather data from mobile sources will vastly improve the ability to detect and forecast weather and road conditions, and will provide the capability to manage road-weather response on specific roadway links. The RWMP is currently demonstrating how weather, road conditions, and related vehicle data can be used for decision making through an innovative Integrated Mobile Observations project. FHWA is partnering with 3 DOTs (MN, MI, & NV) to pilot these applications. One is a mobile alerts application called the Motorists Advisories and Warnings (MAW) and a maintenance decision support application. These applications blend traditional weather information (e.g., radar, surface stations) with mobile vehicle data (e.g., temperature, brake status, wiper status) to determine current weather conditions. These weather conditions, and other road-travel-relevant information, are provided to users via web and phone applications. The MAW provides nowcasts and short-term forecasts out to 24 hours while the EMDSS application can provide forecasts up to 72 hours in advance. The three DOTs have placed readers and external

  7. The new approach of polarimetric attenuation correction for improving radar quantitative precipitation estimation(QPE)

    NASA Astrophysics Data System (ADS)

    Gu, Ji-Young; Suk, Mi-Kyung; Nam, Kyung-Yeub; Ko, Jeong-Seok; Ryzhkov, Alexander

    2016-04-01

    To obtain high-quality radar quantitative precipitation estimation data, reliable radar calibration and efficient attenuation correction are very important. Because microwave radiation at shorter wavelength experiences strong attenuation in precipitation, accounting for this attenuation is the essential work at shorter wavelength radar. In this study, the performance of different attenuation/differential attenuation correction schemes at C band is tested for two strong rain events which occurred in central Oklahoma. And also, a new attenuation correction scheme (combination of self-consistency and hot-spot concept methodology) that separates relative contributions of strong convective cells and the rest of the storm to the path-integrated total and differential attenuation is among the algorithms explored. A quantitative use of weather radar measurement such as rainfall estimation relies on the reliable attenuation correction. We examined the impact of attenuation correction on estimates of rainfall in heavy rain events by using cross-checking with S-band radar measurements which are much less affected by attenuation and compared the storm rain totals obtained from the corrected Z and KDP and rain gages in these cases. This new approach can be utilized at shorter wavelength radars efficiently. Therefore, it is very useful to Weather Radar Center of Korea Meteorological Administration preparing X-band research dual Pol radar network.

  8. Engineering Evaluation and Calibration of Iowa X-Band Polarimetric Radars

    NASA Astrophysics Data System (ADS)

    Vijay Mishra, Kumar; Kruger, Anton; Krajewski, Witold

    2013-04-01

    The detailed knowledge and extensive monitoring of the precipitation structure at smaller temporal and spatial scales are critical to the scientific understanding of the hydrological cycle and associated processes. The hydrometeorological information at smaller scales is usually not available with the current weather radar systems which operate at lower frequencies such as S- and C-bands. This has necessitated the use of higher frequency (X-band) weather radars to obtain rainfall data at improved accuracy and near-ground coverage at shorter ranges. The University of Iowa has acquired four scanning, mobile, X-band polarimetric (XPOL) Doppler weather radars with the objective of accurate quantitative estimation of the rainfall at a high temporal and spatial resolution. These four XPOL radars will be deployed for short-range multiple-view observations of the same weather event thus reducing uncertainties introduced by the signal attenuation and instrument-wide errors. This network of radars is intended to serve multiple areas of hydrological research including uncertainty modelling, urban hydrology, flood and flash-flood prediction, and soil erosion. Compared to the existing networks of X-band weather radars, several features place the XPOL radar systems in a distinctly attractive position for the scientific community. Firstly, the Iowa XPOL radars are mounted on mobile platforms, and consequently, are deployed at any location of interest. Secondly, these systems are capable of acquiring data at a programmable range sampling which can be as low as 30m. Thirdly, the use of dual-polarization provides additional information about the hydrometeors at smaller scales. The radars can operate in staggered PRT and dual-PRF pulsing modes and can process data using either standard pulse-pair or spectral mode techniques. The Iowa XPOL radar systems are currently being evaluated and calibrated to participate in their first field campaigns in the upcoming NASA IFloodS (Iowa Flood

  9. Diagnostic analysis of a heavy rainfall event over Beijing on July 21-22, 2012

    NASA Astrophysics Data System (ADS)

    Jiang, X.; Yuan, H.

    2012-12-01

    The eastward moving low vortex over the North China plain induced the heaviest rainfall in 61 years over Beijing on July 21-22, 2012. This record-breaking heavy rainfall is characterized by its great rainfall amount and intensity, wide range, and high impact, causing dozens of deaths and extensive damage. In this paper, using a set of measurements and the NCEP 1°×1° reanalysis data, the synoptic and mesoscale conditions of the heavy rainfall are firstly diagnosed. The measurements include the intensive surface observations, the observations of the operational sounding station and microwave radiometer, as well as the products of Doppler radar and satellite. Preliminary analysis shows that the eastward moving cold front encounters the warm moist southwest flow around Subtropical High, providing a favorable circulation condition for strong convective weather in this East Asian monsoon region. Meanwhile, the conditions of sustained water vapor, strong vertical ascent of air and unstable stratification are suitable for the formation of a heavy rainfall over Beijing. The mesoscale convective systems (MCSs) which produced the most severe rainfall in Fang Shan area are then analyzed, and the radar and satellite data with mesoscale model forecasts are used to further examine the features of the MCSs evolution. Moreover, the effects of topography and urban heat island which may contribute to the heavy rainfall are also discussed.; Heavy rainfall in Beijing on July 21, 2012 ; The distribution of precipitation (mm) over Beijing during 0200UTC to 2200UTC, July 21

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

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

    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 μS 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

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  12. Urban Flood Warning Systems using Radar Technologies

    NASA Astrophysics Data System (ADS)

    Fang, N.; Bedient, P. B.

    2013-12-01

    There have been an increasing number of urban areas that rely on weather radars to provide accurate precipitation information for flood warning purposes. As non-structural tools, radar-based flood warning systems can provide accurate and timely warnings to the public and private entities in urban areas that are prone to flash floods. The wider spatial and temporal coverage from radar increases flood warning lead-time when compared to rain and stream gages alone. The Third Generation Rice and Texas Medical Center (TMC) Flood Alert System (FAS3) has been delivering warning information with 2 to 3 hours of lead time and a R2 value of 93% to facility personnel in a readily understood format for more than 50 events in the past 15 years. The current FAS utilizes NEXRAD Level II radar rainfall data coupled with a real-time hydrologic model (RTHEC-1) to deliver warning information. The system has a user-friendly dashboard to provide rainfall maps, Google Maps based inundation maps, hydrologic predictions, and real-time monitoring at the bayou. This paper will evaluate its reliable performance during the recent events occurring in 2012 and 2013 and the development of a similar radar-based flood warning system for the City of Sugar Land, Texas. Having a significant role in the communication of flood information, FAS marks an important step towards the establishment of an operational and reliable flood warning system for flood-prone urban areas.

  13. Areal Rainfall Estimation for Flood Forecasting

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    This study deals with the estimation of catchment areal rainfall for the purpose of real-time flood forecasting using rainfall-runoff models. In the UK the two sources of rainfall data on the appropriate timescale are a sparse network of telemetered raingauges, with typical gauge spacings of 10 to 20km, and rainfall estimates derived from weather radar. The focus here is placed on raingauge estimation of rainfall. A survey of the literature reveals a vast number of methods developed for the estimation of areal rainfall from raingauge measurements on a range of spatial and temporal scales, ranging from simple weighting schemes to more complex interpolation methods. A review of previous method intercomparison studies identifies the need for a full evaluation of methods. Evaluation of a selection of nine weighting methods including Thiessen polygons, Standard Average Annual Rainfall (SAAR) weights and DTM-derived elevation weights has been carried out for two UK catchments. One catchment, the Brue in Somerset, is equipped with a special dense network of raingauges installed as part of the HYREX experiment. Evaluation was carried out using the PDM rainfall-runoff model with areal rainfall estimated from several sub-networks of raingauges and modelled flow compared with observed flow. Modelled flow was also compared with flow modelled using the ‘ground truth’ of areal rainfall estimated from the dense raingauge network. Estimates of 15 minute areal rainfall using each method were also compared directly with the areal estimate from the dense network for individual events characterised by either convective or stratiform rain. For stratiform rain, results indicated that all methods give reasonably accurate results, even when only two gauges are used, and the performances of the methods tested were almost indistinguishable. For convective rain, the Thiessen method gave consistently better results than the other methods, and the SAAR-method gave consistently worse

  14. Categorisation of northern California rainfall for periods with and without a radar brightband using stable isotopes and a novel automated precipitation collector

    USGS Publications Warehouse

    Coplen, Tyler B.; Paul J. Neiman,; Allen B. White,; Ralph, F. Martin

    2015-01-01

    During landfall of extratropical cyclones between 2005 and 2011, nearly 1400 precipitation samples were collected at intervals of 30-min time resolution with novel automated collectors at four NOAA sites in northern California [Alta (ATA), Bodega Bay (BBY), Cazadero (CZD) and Shasta Dam (STD)] during 43 events. Substantial decreases were commonly followed hours later by substantial increases in hydrogen isotopic composition (δ2HVSMOW where VSMOW is Vienna Standard Mean Ocean Water) and oxygen isotopic composition (δ18OVSMOW) of precipitation. These variations likely occur as pre-cold frontal precipitation generation transitions from marine vapour masses having low rainout to cold cloud layers having much higher rainout (with concomitant brightband signatures measured by an S-band profiling radar and lower δ2HVSMOW values of precipitation), and finally to shallower, warmer precipitating clouds having lower rainout (with non-brightband signatures and higher δ2HVSMOW values of precipitation), in accord with ‘seeder–feeder’ precipitation. Of 82 intervals identified, a remarkable 100.5 ‰ decrease in δ2HVSMOW value was observed for a 21 January 2010 event at BBY. Of the 61 intervals identified with increases in δ2HVSMOW values as precipitation transitioned to shallower, warmer clouds having substantially less rainout (the feeder part of the seeder–feeder mechanism), a remarkable increase in δ2HVSMOW value of precipitation of 82.3 ‰ was observed for a 10 February 2007 event at CZD. All CZD and ATA events having δ2HVSMOW values of precipitation below −105 ‰ were atmospheric rivers (ARs), and of the 13 events having δ2HVSMOWvalues of precipitation below −80 ‰, 77 % were ARs. Cloud echo-top heights (a proxy for atmospheric temperature) were available for 23 events. The mean echo-top height is greater for higher rainout periods than that for lower rainout periods in 22 of the 23 events. The lowest δ2HVSMOW of precipitation of 28

  15. Remote sensing of rainfall for flash flood prediction in the United States

    NASA Astrophysics Data System (ADS)

    Gourley, J. J.; Flamig, Z.; Vergara, H. J.; Clark, R. A.; Kirstetter, P.; Terti, G.; Hong, Y.; Howard, K.

    2015-12-01

    This presentation will briefly describe the Multi-Radar Multi-Sensor (MRMS) system that ingests all NEXRAD and Canadian weather radar data and produces accurate rainfall estimates at 1-km resolution every 2 min. This real-time system, which was recently transitioned for operational use in the National Weather Service, provides forcing to a suite of flash flood prediction tools. The Flooded Locations and Simulated Hydrographs (FLASH) project provides 6-hr forecasts of impending flash flooding across the US at the same 1-km grid cell resolution as the MRMS rainfall forcing. This presentation will describe the ensemble hydrologic modeling framework, provide an evaluation at gauged basins over a 10-year period, and show the FLASH tools' performance during the record-setting floods in Oklahoma and Texas in May and June 2015.

  16. The Weather Radar Toolkit, National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center's support of interoperability and the Global Earth Observation System of Systems (GEOSS)

    NASA Astrophysics Data System (ADS)

    Ansari, S.; Del Greco, S.

    2006-12-01

    In February 2005, 61 countries around the World agreed on a 10 year plan to work towards building open systems for sharing geospatial data and services across different platforms worldwide. This system is known as the Global Earth Observation System of Systems (GEOSS). The objective of GEOSS focuses on easy access to environmental data and interoperability across different systems allowing participating countries to measure the "pulse" of the planet in an effort to advance society. In support of GEOSS goals, NOAA's National Climatic Data Center (NCDC) has developed radar visualization and data exporter tools in an open systems environment. The NCDC Weather Radar Toolkit (WRT) loads Weather Surveillance Radar 1988 Doppler (WSR-88D) volume scan (S-band) data, known as Level-II, and derived products, known as Level-III, into an Open Geospatial Consortium (OGC) compliant environment. The application is written entirely in Java and will run on any Java- supported platform including Windows, Macintosh and Linux/Unix. The application is launched via Java Web Start and runs on the client machine while accessing these data locally or remotely from the NCDC archive, NOAA FTP server or any URL or THREDDS Data Server. The WRT allows the data to be manipulated to create custom mosaics, composites and precipitation estimates. The WRT Viewer provides tools for custom data overlays, Web Map Service backgrounds, animations and basic filtering. The export of images and movies is provided in multiple formats. The WRT Data Exporter allows for data export in both vector polygon (Shapefile, Well-Known Text) and raster (GeoTIFF, ESRI Grid, VTK, NetCDF, GrADS) formats. By decoding the various Radar formats into the NetCDF Common Data Model, the exported NetCDF data becomes interoperable with existing software packages including THREDDS Data Server and the Integrated Data Viewer (IDV). The NCDC recently partnered with NOAA's National Severe Storms Lab (NSSL) to decode Sigmet C-band Doppler

  17. Uncertainties on the definition of critical rainfall patterns for debris-flows triggering. Results from the Rebaixader monitoring site (Central Pyrenees)

    NASA Astrophysics Data System (ADS)

    Hürlimann, Marcel; Abancó, Clàudia; Moya, Jose; Berenguer, Marc

    2015-04-01

    Empirical rainfall thresholds are a widespread technique in debris-flow hazard assessment and can be established by statistical analysis of historic data. Typically, data from one or several rain gauges located nearby the affected catchment is used to define the triggering conditions. However, this procedure has been demonstrated not to be accurate enough due to the spatial variability of convective rainstorms. In 2009, a monitoring system was installed in the Rebaixader catchment, Central Pyrenees (Spain). Since then, 28 torrential flows (debris flows and debris floods) have occurred and rainfall data of 25 of them are available with a 5-minutes frequency of recording ("event rainfalls"). Other 142 rainfalls that did not trigger events ("no event rainfalls) were also collected and analysed. The goal of this work was threefold: a) characterize rainfall episodes in the Rebaixader catchment and compare rainfall data that triggered torrential events and others that did not; b) define and test Intensity-Duration (ID) thresholds using rainfall data measured inside the catchment; c) estimate the uncertainty derived from the use of rain gauges located outside the catchment based on the spatial correlation depicted by radar rainfall maps. The results of the statistical analysis showed that the parameters that more distinguish between the two populations of rainfalls are the rainfall intensities, the mean rainfall and the total precipitation. On the other side, the storm duration and the antecedent rainfall are not significantly different between "event rainfalls" and "no event rainfalls". Four different ID rainfall thresholds were derived based on the dataset of the first 5 years and tested using the 2014 dataset. The results of the test indicated that the threshold corresponding to the 90% percentile showed the best performance. Weather radar data was used to analyse the spatial variability of the triggering rainfalls. The analysis indicates that rain gauges outside the

  18. Real Time Detection of Anomalies in Streaming Radar and Rain Gauge Data

    NASA Astrophysics Data System (ADS)

    Hill, D. J.; Minsker, B.; Amir, E.; Choi, J.

    2008-12-01

    Radar-rainfall data are being used in an increasing number of real-time applications because of their wide spatial and temporal coverage. Because of uncertainties in radar measurements and the relationship between radar measurements and rainfall on the ground, radar-rainfall data are often combined with rain gauge data to improve their accuracy. While rain gauges can provide accurate estimates of rainfall, their data are sometimes subject to a number of errors caused by the environment in which the gauges are deployed. This study develops a method for automatically detecting anomalies (i.e. data that deviate markedly from historical patterns) in both radar and raingauge data through integration and modeling of data from these two different sources.. These anomalous data can be caused by sensor or data transmission errors or by infrequent system behaviors that may be of interest to the scientific or public safety communities. This study develops an automated anomaly detection method that employs a Dynamic Bayesian Network to assimilate data from multiple rain gauges and weather radar (NEXRAD) into an uncertain model of the current rainfall. Filtering (e.g. Kalman filtering) can then be used to infer the likelihood that a particular gauge measurement is anomalous. Measurements with a high likelihood of being anomalous are classified as such. The method developed in this study performs fast, incremental evaluation of data as they become available; scales to large quantities of data; and requires no a priori information regarding process variables or types of anomalies that may be encountered. The performance of the anomaly detector developed in this study is demonstrated using a precipitation sensor network composed of a NEXRAD weather radar and several near- real-time telemetered rain gauges deployed by the USGS in Chicago. The results indicate that the method performs well at identifying anomalous data caused by a real sensor failure.

  19. Calibration and evaluation of a flood forecasting system: Utility of numerical weather prediction model, data assimilation and satellite-based rainfall

    NASA Astrophysics Data System (ADS)

    Yucel, I.; Onen, A.; Yilmaz, K. K.; Gochis, D. J.

    2015-04-01

    A fully-distributed, multi-physics, multi-scale hydrologic and hydraulic modeling system, WRF-Hydro, is used to assess the potential for skillful flood forecasting based on precipitation inputs derived from the Weather Research and Forecasting (WRF) model and the EUMETSAT Multi-sensor Precipitation Estimates (MPEs). Similar to past studies it was found that WRF model precipitation forecast errors related to model initial conditions are reduced when the three dimensional atmospheric data assimilation (3DVAR) scheme in the WRF model simulations is used. A comparative evaluation of the impact of MPE versus WRF precipitation estimates, both with and without data assimilation, in driving WRF-Hydro simulated streamflow is then made. The ten rainfall-runoff events that occurred in the Black Sea Region were used for testing and evaluation. With the availability of streamflow data across rainfall-runoff events, the calibration is only performed on the Bartin sub-basin using two events and the calibrated parameters are then transferred to other neighboring three ungauged sub-basins in the study area. The rest of the events from all sub-basins are then used to evaluate the performance of the WRF-Hydro system with the calibrated parameters. Following model calibration, the WRF-Hydro system was capable of skillfully reproducing observed flood hydrographs in terms of the volume of the runoff produced and the overall shape of the hydrograph. Streamflow simulation skill was significantly improved for those WRF model simulations where storm precipitation was accurately depicted with respect to timing, location and amount. Accurate streamflow simulations were more evident in WRF model simulations where the 3DVAR scheme was used compared to when it was not used. Because of substantial dry bias feature of MPE, as compared with surface rain gauges, streamflow derived using this precipitation product is in general very poor. Overall, root mean squared errors for runoff were reduced by

  20. Measurement and interpolation uncertainties in rainfall maps from cellular communication networks

    NASA Astrophysics Data System (ADS)

    Rios Gaona, M. F.; Overeem, A.; Leijnse, H.; Uijlenhoet, R.

    2015-08-01

    Accurate measurements of rainfall are important in many hydrological and meteorological applications, for instance, flash-flood early-warning systems, hydraulic structures design, irrigation, weather forecasting, and climate modelling. Whenever possible, link networks measure and store the received power of the electromagnetic signal at regular intervals. The decrease in power can be converted to rainfall intensity, and is largely due to the attenuation by raindrops along the link paths. Such an alternative technique fulfils the continuous effort to obtain measurements of rainfall in time and space at higher resolutions, especially in places where traditional rain gauge networks are scarce or poorly maintained. Rainfall maps from microwave link networks have recently been introduced at country-wide scales. Despite their potential in rainfall estimation at high spatiotemporal resolutions, the uncertainties present in rainfall maps from link networks are not yet fully comprehended. The aim of this work is to identify and quantify the sources of uncertainty present in interpolated rainfall maps from link rainfall depths. In order to disentangle these sources of uncertainty, we classified them into two categories: (1) those associated with the individual microwave link measurements, i.e. the errors involved in link rainfall retrievals, such as wet antenna attenuation, sampling interval of measurements, wet/dry period classification, dry weather baseline attenuation, quantization of the received power, drop size distribution (DSD), and multi-path propagation; and (2) those associated with mapping, i.e. the combined effect of the interpolation methodology and the spatial density of link measurements. We computed ~ 3500 rainfall maps from real and simulated link rainfall depths for 12 days for the land surface of the Netherlands. Simulated link rainfall depths refer to path-averaged rainfall depths obtained from radar data. The ~ 3500 real and simulated rainfall maps were

  1. Use of Dual Polarization Radar in Validation of Satellite Precipitation Measurements: Rationale and Opportunities

    NASA Technical Reports Server (NTRS)

    Chandrasekar, V.; Hou, Arthur; Smith, Eric; Bringi, V. N.; Rutledge, S. A.; Gorgucci, E.; Petersen, W. A.; SkofronickJackson, Gail

    2008-01-01

    Dual-polarization weather radars have evolved significantly in the last three decades culminating in the operational deployment by the National Weather Service. In addition to operational applications in the weather service, dual-polarization radars have shown significant potential in contributing to the research fields of ground based remote sensing of rainfall microphysics, study of precipitation evolution and hydrometeor classification. Furthermore the dual-polarization radars have also raised the awareness of radar system aspects such as calibration. Microphysical characterization of precipitation and quantitative precipitation estimation are important applications that are critical in the validation of satellite borne precipitation measurements and also serves as a valuable tool in algorithm development. This paper presents the important role played by dual-polarization radar in validating space borne precipitation measurements. Starting from a historical evolution, the various configurations of dual-polarization radar are presented. Examples of raindrop size distribution retrievals and hydrometeor type classification are discussed. The quantitative precipitation estimation is a product of direct relevance to space borne observations. During the TRMM program substantial advancement was made with ground based polarization radars specially collecting unique observations in the tropics which are noted. The scientific accomplishments of relevance to space borne measurements of precipitation are summarized. The potential of dual-polarization radars and opportunities in the era of global precipitation measurement mission is also discussed.

  2. A Study of the Use of Meteorological Satellite, Weather Radar, and Integrated Graphics Products in the Flight Service Station System.

    DTIC Science & Technology

    1980-04-01

    watershed hydrological estimates, tops maps, and a vertically integrated liquid water content (VIL) map. System movement vectors are computed, and a flash ... flood monitor is maintained. The maps produced are not exact images of the picture seen on the radar CRT, but rather are processed data presented on

  3. Satellite Observations For Calibration of Ground Radar Networks

    NASA Astrophysics Data System (ADS)

    Schwaller, M.; Morris, K.

    2011-12-01

    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

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

    PubMed

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

    2008-01-01

    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.

  5. 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

    Mead, Reginald; Paxton, John; Sojda, Richard S.; Swayne, David A.; Yang, Wanhong; Voinov, A.A.; Rizzoli, A.; Filatova, T.

    2010-01-01

    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.

  6. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  7. Spatial and temporal variations in rainfall over Darwin and its vicinity during different large-scale environments

    NASA Astrophysics Data System (ADS)

    Rauniyar, Surendra P.; Walsh, Kevin J. E.

    2016-02-01

    This study analyses the regional variations in rainfall over Darwin and its vicinity due to different large-scale circulations during the Australian summer by utilizing the combination of in situ and C-band polarimetric radar rainfall data at hourly resolution. The eight phases of the Madden-Julian oscillation as defined by Wheeler and Hendon (Mon Weather Rev 132(8):1917-1932, 2004) were used as indicators of different large-scale environments. The analysis found that the large-scale forcing starts to build up from phase 4 by the reversal of low- to mid-level easterly winds to moist westerly winds, reaching a maximum in phase 5 and weakening through phases 6-7. During phases 4-6, most of the study domain experiences widespread rainfall, but with distinct spatial and temporal structures. In addition, during these phases, coastal areas near Darwin receive more rainfall in the early morning (0200-0400 LT) due to the spreading or expansion of rainfall from the Beagle Gulf, explaining the occurrence of a secondary diurnal rainfall peak over Darwin. In contrast, local-scale mechanisms (sea breezes) reinvigorate from phase 8, further strengthening through phases 1-3, when low-level easterly winds become established over Darwin producing rainfall predominately over land and island locations during the afternoon. During these phases, below average rainfall is observed over most of the radar domain, except over the Tiwi Islands in phase 2.

  8. Use of radar QPE for the derivation of Intensity-Duration-Frequency curves in a range of climatic regimes

    NASA Astrophysics Data System (ADS)

    Marra, Francesco; Morin, Efrat

    2015-12-01

    Intensity-Duration-Frequency (IDF) curves are widely used in flood risk management because they provide an easy link between the characteristics of a rainfall event and the probability of its occurrence. Weather radars provide distributed rainfall estimates with high spatial and temporal resolutions and overcome the scarce representativeness of point-based rainfall for regions characterized by large gradients in rainfall climatology. This work explores the use of radar quantitative precipitation estimation (QPE) for the identification of IDF curves over a region with steep climatic transitions (Israel) using a unique radar data record (23 yr) and combined physical and empirical adjustment of the radar data. IDF relationships were derived by fitting a generalized extreme value distribution to the annual maximum series for durations of 20 min, 1 h and 4 h. Arid, semi-arid and Mediterranean climates were explored using 14 study cases. IDF curves derived from the study rain gauges were compared to those derived from radar and from nearby rain gauges characterized by similar climatology, taking into account the uncertainty linked with the fitting technique. Radar annual maxima and IDF curves were generally overestimated but in 70% of the cases (60% for a 100 yr return period), they lay within the rain gauge IDF confidence intervals. Overestimation tended to increase with return period, and this effect was enhanced in arid climates. This was mainly associated with radar estimation uncertainty, even if other effects, such as rain gauge temporal resolution, cannot be neglected. Climatological classification remained meaningful for the analysis of rainfall extremes and radar was able to discern climatology from rainfall frequency analysis.

  9. On the sensitivity of urban hydrodynamic modelling to rainfall spatial and temporal resolution

    NASA Astrophysics Data System (ADS)

    Bruni, G.; Reinoso, R.; van de Giesen, N. C.; Clemens, F. H. L. R.; ten Veldhuis, J. A. E.

    2015-02-01

    Cities are increasingly vulnerable to floods generated by intense rainfall, because of urbanisation of flood-prone areas and ongoing urban densification. Accurate information of convective storm characteristics at high spatial and temporal resolution is a crucial input for urban hydrological models to be able to simulate fast runoff processes and enhance flood prediction in cities. In this paper, a detailed study of the sensitivity of urban hydrodynamic response to high resolution radar rainfall was conducted. Rainfall rates derived from X-band dual polarimetric weather radar were used as input into a detailed hydrodynamic sewer model for an urban catchment in the city of Rotterdam, the Netherlands. The aim was to characterise how the effect of space and time aggregation on rainfall structure affects hydrodynamic modelling of urban catchments, for resolutions ranging from 100 to 2000 m and from 1 to 10 min. Dimensionless parameters were derived to compare results between different storm conditions and to describe the effect of rainfall spatial resolution in relation to storm characteristics and hydrodynamic model properties: rainfall sampling number (rainfall resolution vs. storm size), catchment sampling number (rainfall resolution vs. catchment size), runoff and sewer sampling number (rainfall resolution vs. runoff and sewer model resolution respectively). Results show that for rainfall resolution lower than half the catchment size, rainfall volumes mean and standard deviations decrease as a result of smoothing of rainfall gradients. Moreover, deviations in maximum water depths, from 10 to 30% depending on the storm, occurred for rainfall resolution close to storm size, as a result of rainfall aggregation. Model results also showed that modelled runoff peaks are more sensitive to rainfall resolution than maximum in-sewer water depths as flow routing has a damping effect on in-sewer water level variations. Temporal resolution aggregation of rainfall inputs led to

  10. The proposed flatland radar

    NASA Technical Reports Server (NTRS)

    Green, J. L.; Gage, K. S.; Vanzandt, T. E.; Nastrom, G. D.

    1986-01-01

    A flexible very high frequency (VHF) stratosphere-troposphere (ST) radar configured for meteorological research is to be constructed near Urbana, Illinois. Measurement of small vertical velocities associated with synoptic-scale meteorology can be performed. A large Doppler microwave radar (CHILL) is located a few km from the site of the proposed ST radar. Since the microwave radar can measure the location and velocity of hydrometeors and the VHF ST radar can measure clear (or cloudy) air velocities, simultaneous observations by these two radars of stratiform or convective weather systems would provide valuable meteorological information.

  11. Design of rain gauge networks for flash flood prediction: assessment based on spatial moments of catchment rainfall

    NASA Astrophysics Data System (ADS)

    Marra, F.; Zoccatelli, D.

    2012-04-01

    Despite the availability of weather radar data at high spatial (1 km2) and temporal (5-15 min) resolution, ground-based rain gauges continue to be necessary for accurate estimation of storm rainfall input to catchments during flash flood events, especially in terrain characterized by complex orography. A long-standing problem in catchment hydrology is to establish optimal placement and density of a rain gauge network to acquire data on both rainfall depth and spatiotemporal variability of intensity during extreme storm events. Using weather radar observations and a dense network of rain gauges, this study examines whether it is possible to determine a reliable "best" set of rain gauge locations for a number of catchments subject to flash floods observed in Europe. High-quality rainfall data are used to evaluate several configurations of a raingauge network with variable spatial densities. A methodology is used for the selection of raingauge sites, given a certain spatial density, which is based on the use of the spatial moments of catchment rainfall. This set of statistics quantifies the dependence existing between spatial rainfall organisation, basin morphology and runoff response. These statistics describe the spatial rainfall organisation in terms of position and dispersion as a function of the distance measured along the flow routing coordinate. Rainfall estimates obtained from the 'optimised' raingauge network are used as input for a distributed hydrological model. Results from these simulations are compared with those obtained by using the measured rainfall and with those obtained by estimating rainfall from randomly designed network ensembles. Our results show that indications from the optimization of the spatial moments of catchment rainfall may help to provide a robust design for rain gauge network design.

  12. Minimizing uncertainty of daily rainfall interpolation over large catchments through realistic sampling of anisotropic correlogram parameters

    NASA Astrophysics Data System (ADS)

    Gyasi-Agyei, Yeboah

    2016-04-01

    It has been established that daily rainfall gauged network density is not adequate for the level of hydrological modelling required of large catchments involving pollutant and sediment transport, such as the catchments draining the coastal regions of Queensland, Australia, to the sensitive Great Barrier Reef. This paper seeks to establish a link between the spatial structure of radar and gauge rainfall for improved interpolation of the limited gauged data over a grid or functional units of catchments in regions with or without radar records. The study area is within Mt. Stapylton weather radar station range, a 128 km square region for calibration and validation, and the Brisbane river catchment for validation only. Two time periods (2000-01-01 to 2008-12-31 and 2009-01-01 to 2015-06-30) were considered, the later period for calibration when radar records were available and both time periods for validation without regard to radar information. Anisotropic correlograms of both the gauged and radar data were developed and used to establish the linkage required for areas without radar records. The maximum daily temperature significantly influenced the distributional parameters of the linkage. While the gauged, radar and sampled correlogram parameters reproduced the mean estimates similarly using leave-one-out cross-validation of Ordinary Kriging, the gauged parameters overestimated the standard deviation (SD) which reflects uncertainty by over 91% of cases compared with the radar or the sampled parameter sets. However, the distribution of the SD generated by the radar and the sampled correlogram parameters could not be distinguished, with a Kolmogorov-Smirnov test p-value of 0.52. For the validation case with the catchment, the percentage overestimation of SD by the gauged parameter sets decreased to 81.2% and 87.1% for the earlier and later time periods, respectively. It is observed that the extreme wet days' parameters and statistics were fairly widely distributed

  13. Federal Aviation Administration weather program to improve aviation safety

    NASA Technical Reports Server (NTRS)

    Wedan, R. W.

    1983-01-01

    The implementation of the National Airspace System (NAS) will improve safety services to aviation. These services include collision avoidance, improved landing systems and better weather data acquisition and dissemination. The program to improve the quality of weather information includes the following: Radar Remote Weather Display System; Flight Service Automation System; Automatic Weather Observation System; Center Weather Processor, and Next Generation Weather Radar Development.

  14. Comparison of short-term rainfall forecasts for model-based flow prediction in urban drainage systems.

    PubMed

    Thorndahl, Søren; Poulsen, Troels Sander; Bøvith, Thomas; Borup, Morten; Ahm, Malte; Nielsen, Jesper Ellerbæk; Grum, Morten; Rasmussen, Michael R; Gill, Rasphall; Mikkelsen, Peter Steen

    2013-01-01

    Forecast-based flow prediction in drainage systems can be used to implement real-time control of drainage systems. This study compares two different types of rainfall forecast - a radar rainfall extrapolation-based nowcast model and a numerical weather prediction model. The models are applied as input to an urban runoff model predicting the inlet flow to a waste water treatment plant. The modelled flows are auto-calibrated against real-time flow observations in order to certify the best possible forecast. Results show that it is possible to forecast flows with a lead time of 24 h. The best performance of the system is found using the radar nowcast for the short lead times and the weather model for larger lead times.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  16. Calibration of the Z-R equation for a polarimetric radar located in Sabancuy, Mexico.

    NASA Astrophysics Data System (ADS)

    Noe Paredes-Victoria, Pedro; Rico-Ramirez, Miguel Angel; Pedrozo-Acuña, Adrian

    2016-04-01

    Rainfall estimation using weather radar has been the keystone in several hydrometeorological applications (Bringi & Chandrasekar, 2001) such as flood forecasting and water balance analysis. Additionally, in large spatiotemporal scales, an integrated network of weather radars provide an invaluable quantity of measured data to be applied to regional studies (Kitchen et al., 1994; Westrick et al., 1999). However, each radar must be individually analysed because the characteristics of calibration and local issues are unique and, therefore require further research (Krajewski and Smith, 1991). For instance, the rainfall rate R and the radar reflectivity Z are represented for the total number of a finite number of drops in a volume of scan and it has been demonstrated that these variables can be expressed into a nonlinear representation Z-R (Marshall & Palmer, 1948) and this relationship is unique and depends on the study region and the type of precipitation. In this study we used data from the Sabancuy-radar located in Campeche, Mexico (Latitude +18.9724, Longitude -91.1726) to estimate rainfall distributions into the convective contour in the Gulf of Mexico. This area counts with a long history of tropical storms and hurricanes which produce extreme rainfall causing flood events and important socioeconomic damages into this region. Therefore, the weather radar calibration and Z-R relationship was achieved applying current methodologies (e.g. Probability Matching Method, PMM) and using raingauges in two different temporal scales (daily and each 10 minutes). Thus, rainfall estimations using weather radar can be used to quantitative evaluate the accuracy of parametrizations of atmospheric models and also the results are particularly useful for error analysis in hydrometeorological modelling (Smith et al., 1975; Sun & Crook., 1997). Finally, a better estimation of rainfall in time and space (and forecasting: in short and long term) is a valuable source of information (Jones

  17. Adaptive Radar Data Quality Control and Ensemble-Based Assimilation for Analyzing and Forecasting High-Impact Weather

    DTIC Science & Technology

    2012-09-30

    Assimilation for Analyzing and Forecasting High-Impact Weather Qin Xu CIMMS , University of Oklahoma 120 David L. Boren Blvd. Norman, OK 73072...The data collections and QC algorithm developments are performed by project- supported research scientists at CIMMS , the University of Oklahoma. Dr...PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) CIMMS , University of Oklahoma 120 David L

  18. Adaptive Radar Data Quality Control and Ensemble-Based Assimilation for Analyzing and Forecasting High-Impact Weather

    DTIC Science & Technology

    2013-09-30

    Assimilation for Analyzing and Forecasting High-Impact Weather Qin Xu CIMMS , University of Oklahoma 120 David L. Boren Blvd. Norman, OK 73072...implementations. The data collections and QC algorithm developments are performed by project- supported research scientists at CIMMS , the University of Oklahoma. Dr...Oklahoma, CIMMS ,120 David L. Boren Blvd. ,Norman,OK,73072 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES

  19. Adaptive Radar Data Quality Control and Ensemble-Based Assimilation for Analyzing and Forecasting High-Impact Weather

    DTIC Science & Technology

    2010-09-30

    Assimilation for Analyzing and Forecasting High-Impact Weather Qin Xu CIMMS , University of Oklahoma 120 David L. Boren Blvd. Norman, OK 73072...ADDRESS(ES) University of Oklahoma, CIMMS ,120 David L. Boren Blvd,Norman,OK,73072 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING...research scientists at CIMMS , the University of Oklahoma. Collaborations between this project and the development of the NWRT PAR is coordinated by

  20. Characteristics of the 14 April 1999 Sydney hailstorm based on ground observations, weather radar, insurance data and emergency calls

    NASA Astrophysics Data System (ADS)

    Schuster, S. S.; Blong, R. J.; Leigh, R. J.; McAneney, K. J.

    2005-08-01

    Hailstorms occur frequently in metropolitan Sydney, in the eastern Australian State of New South Wales, which is especially vulnerable due to its building exposure and geographical location. Hailstorms challenge disaster response agencies and pose a great risk for insurance companies. This study focuses on the Sydney hailstorm of 14 April 1999 - Australia's most expensive insured natural disaster, with supporting information from two other storms. Comparisons are drawn between observed hailstone sizes, radar-derived reflectivity and damage data in the form of insurance claims and emergency calls. The "emergency response intensity" (defined by the number of emergency calls as a proportion of the total number of dwellings in a Census Collection District) is a useful new measure of the storm intensity or severity experienced. The area defined by a radar reflectivity ≥55 dBZ appears to be a good approximation of the damage swath on ground. A preferred area for hail damage is located to the left side of storm paths and corresponds well with larger hailstone sizes. Merging hail cells appear to cause a substantially higher emergency response intensity, which also corresponds well to maximum hailstone sizes. A damage threshold could be identified for hailstone sizes around 2.5 cm (1 cm), based on the emergency response intensity (insurance claims). Emergency response intensity and claims costs both correlate positively with hailstone sizes. Higher claim costs also occurred in areas that experienced higher emergency response intensities.

  1. Cascading rainfall uncertainty into flood inundation impact models

    NASA Astrophysics Data System (ADS)

    Souvignet, Maxime; Freer, Jim E.; de Almeida, Gustavo A. M.; Coxon, Gemma; Neal, Jeffrey C.; Champion, Adrian J.; Cloke, Hannah L.; Bates, Paul D.

    2014-05-01

    Observed and numerical weather prediction (NWP) simulated precipitation products typically show differences in their spatial and temporal distribution. These differences can considerably influence the ability to predict hydrological responses. For flood inundation impact studies, as in forecast situations, an atmospheric-hydrologic-hydraulic model chain is needed to quantify the extent of flood risk. Uncertainties cascaded through the model chain are seldom explored, and more importantly, how potential input uncertainties propagate through this cascade, and how best to approach this, is still poorly understood. This requires a combination of modelling capabilities, the non-linear transformation of rainfall to river flow using rainfall-runoff models, and finally the hydraulic flood wave propagation based on the runoff predictions. Improving the characterisation of uncertainty, and what is important to include, in each component is important for quantifying impacts and understanding flood risk for different return periods. In this paper, we propose to address this issue by i) exploring the effects of errors in rainfall on inundation predictive capacity within an uncertainty framework by testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products) and ii) testing different techniques to cascade uncertainties (e.g. bootstrapping, PPU envelope) within the GLUE (generalised likelihood uncertainty estimation) framework. Our method cascades rainfall uncertainties into multiple rainfall-runoff model structures using the Framework for Understanding Structural Errors (FUSE). The resultant prediction uncertainties in upstream discharge provide uncertain boundary conditions that are cascaded into a simplified shallow water hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded radar data and numerical weather predictions (NWP) models are evaluated

  2. 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)

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

    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.

  3. Probabilistic rainfall warning system with an interactive user interface

    NASA Astrophysics Data System (ADS)

    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

    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

  4. Comparison of machine learning algorithms for their applicability in satellite-based optical rainfall retrievals

    NASA Astrophysics Data System (ADS)

    Meyer, Hanna; Kühnlein, Meike; Appelhans, Tim; Nauss, Thomas

    2015-04-01

    Machine learning (ML) algorithms have been successfully evaluated as valuable tools in satellite-based rainfall retrievals which shows the high potential of ML algorithms when faced with high dimensional and complex data. Moreover, the recent developments in parallel computing with ML offer new possibilities in terms of training and predicting speed and therefore makes their usage in real time systems feasible. The present study compares four ML algorithms for rainfall area detection and rainfall rate assignment during daytime, night-time and twilight using MSG SEVIRI data over Germany. Satellite-based proxies for cloud top height, cloud top temperature, cloud phase and cloud water path are applied as predictor variables. As machine learning algorithms, random forests (RF), neural networks (NNET), averaged neural networks (AVNNET) and support vector machines (SVM) are chosen. The comparison is realised in three steps. First, an extensive tuning study is carried out to customise each of the models. Secondly, the models are trained using the optimum values of model parameters found in the tuning study. Finally, the trained models are used to detect rainfall areas and to assign rainfall rates using an independent validation datasets which is compared against ground-based radar data. To train and validate the models, the radar-based RADOLAN RW product from the German Weather Service (DWD) is used which provides area-wide gauge-adjusted hourly precipitation information. Though the differences in the performance of the algorithms were rather small, NNET and AVNNET have been identified as the most suitable algorithms. On average, they showed the best performance in rainfall area delineation as well as in rainfall rate assignment. The fast computation time of NNET allows to work with large datasets as it is required in remote sensing based rainfall retrievals. However, since none of the algorithms performed considerably better that the others we conclude that research

  5. Critical rainfall conditions for the initiation of torrential flows. Results from the Rebaixader catchment (Central Pyrenees)

    NASA Astrophysics Data System (ADS)

    Abancó, Clàudia; Hürlimann, Marcel; Moya, José; Berenguer, Marc

    2016-10-01

    , and mean intensity, Imean, of the rainfall event, and (ii) using floating durations, D, and intensities, Ifl, based on the maximum values over floating periods of different duration. The resulting thresholds are considerably different (Imean = 6.20 Dtot-0.36 and Ifl_90% = 5.49 D-0.75, respectively) showing a strong dependence on the applied methodology. On the other hand, the definition of the thresholds is affected by several types of uncertainties. Data from both rain gauges and weather radar were used to analyze the uncertainty associated with the spatial variability of the triggering rainfalls. The analysis indicates that the precipitation recorded by the nearby rain gauges can introduce major uncertainties, especially for convective summer storms. Thus, incorporating radar rainfall can significantly improve the accuracy of the measured triggering rainfall. Finally, thresholds were also derived according to three different criteria for the definition of the duration of the triggering rainfall: (i) the duration until the peak intensity, (ii) the duration until the end of the rainfall; and, (iii) the duration until the trigger of the torrential flow. An important contribution of this work is the assessment of the threshold relationships obtained using the third definition of duration. Moreover, important differences are observed in the obtained thresholds, showing that ID relationships are significantly dependent on the applied methodology.

  6. An integrated approach to monitoring the calibration stability of operational dual-polarization radars

    NASA Astrophysics Data System (ADS)

    Vaccarono, Mattia; Bechini, Renzo; Chandrasekar, Chandra V.; Cremonini, Roberto; Cassardo, Claudio

    2016-11-01

    The stability of weather radar calibration is a mandatory aspect for quantitative applications, such as rainfall estimation, short-term weather prediction and initialization of numerical atmospheric and hydrological models. Over the years, calibration monitoring techniques based on external sources have been developed, specifically calibration using the Sun and calibration based on ground clutter returns. In this paper, these two techniques are integrated and complemented with a self-consistency procedure and an intercalibration technique. The aim of the integrated approach is to implement a robust method for online monitoring, able to detect significant changes in the radar calibration. The physical consistency of polarimetric radar observables is exploited using the self-consistency approach, based on the expected correspondence between dual-polarization power and phase measurements in rain. This technique allows a reference absolute value to be provided for the radar calibration, from which eventual deviations may be detected using the other procedures. In particular, the ground clutter calibration is implemented on both polarization channels (horizontal and vertical) for each radar scan, allowing the polarimetric variables to be monitored and hardware failures to promptly be recognized. The Sun calibration allows monitoring the calibration and sensitivity of the radar receiver, in addition to the antenna pointing accuracy. It is applied using observations collected during the standard operational scans but requires long integration times (several days) in order to accumulate a sufficient amount of useful data. Finally, an intercalibration technique is developed and performed to compare colocated measurements collected in rain by two radars in overlapping regions. The integrated approach is performed on the C-band weather radar network in northwestern Italy, during July-October 2014. The set of methods considered appears suitable to establish an online tool to

  7. Validation of simulated hurricane drop size distributions using polarimetric radar

    NASA Astrophysics Data System (ADS)

    Brown, Bonnie R.; Bell, Michael M.; Frambach, Andrew J.

    2016-01-01

    Recent upgrades to the U.S. radar network now allow for polarimetric measurements of landfalling hurricanes, providing a new data set to validate cloud microphysical parameterizations used in tropical cyclone simulations. Polarimetric radar reflectivity and differential reflectivity simulated by the Weather Research and Forecasting model were compared with real radar observations from 2014 in Hurricanes Arthur and Ana. Six different microphysics parameterizations were tested that were able to capture the major features of both hurricanes, including accurate tracks, precipitation asymmetry, and the approximate intensity of the storms. A high correlation between simulated intensity and rainfall across schemes suggests an intimate link between the latent heating produced by the microphysics and the storm dynamics. Most of the parameterizations produced a higher frequency of larger raindrops than observed. The Thompson aerosol-aware bulk and explicit spectral bin microphysical schemes showed the best fidelity to the observations at a higher computational cost.

  8. Validation of Simulated Hurricane Drop Size Distributions using Polarimetric Radar

    NASA Astrophysics Data System (ADS)

    Bell, M. M.; Brown, B. R.; Frambach, A. J.

    2015-12-01

    Recent upgrades to the U.S. radar network now allow for polarimetric measurements of landfalling hurricanes, providing a new dataset to validate cloud microphysical parameterizations used in tropical cyclone simulations. Polarimetric radar variables simulated by the Weather Research and Forecasting model were compared with real radar observations from 2014 in Hurricanes Arthur and Ana. Six different microphysics parameterizations were tested that were able to capture the major features of both hurricanes, including accurate tracks, asymmetric distributions of precipitation, and the approximate intensity of the storms. However, most of the schemes produced a higher frequency of larger raindrops than observed. The Thompson aerosol-aware bulk and a spectral bin microphysical (SBM) scheme showed the best fidelity to the observed joint probability distribution of horizontal and differential reflectivity. The SBM also produced the most accurate intensity and lowest rainfall accumulation, but required much higher computational resources than the bulk schemes.

  9. The Status of the Tropical Rainfall Measuring Mission (TRMM) after 2 Years in Orbit

    NASA Technical Reports Server (NTRS)

    Kummerow, C.; Simpson, J.; Thiele, O.; Barnes, W.; Chang, A. T. C.; Stocker, E.; Adler, R. F.; Hou, A.; Kakar, R.; Wentz, F.

    1999-01-01

    The Tropical Rainfall Measuring Mission (TRMM) satellite was launched on November 27, 1997, and data from all the instruments first became available approximately 30 days after launch. Since then, much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, in related modeling applications and in new datasets tailored specifically for these applications. This paper reports the latest results regarding the calibration of the TRMM Microwave Imager, (TMI), Precipitation Radar (PR) and Visible and Infrared Sensor (VIRS). For the TMI, a new product is in place that corrects for a still unknown source of radiation leaking in to the TMI receiver. The PR calibration has been adjusted upward slightly (by 0.6 dBZ) to better match ground reference targets, while the VIRS calibration remains largely unchanged. In addition to the instrument calibration, great strides have been made with the rainfall algorithms as well, with the new rainfall products agreeing with each other to within less than 20% over monthly zonally averaged statistics. The TRMM Science Data and Information System (TSDIS) has responded equally well by making a number of new products, including real-time and fine resolution gridded rainfall fields available to the modeling community. The TRMM Ground Validation (GV) program is also responding with improved radar calibration techniques and rainfall algorithms to provide more accurate GV products which will be further enhanced with the new multiparameter 10 cm radar being developed for TRMM validation and precipitation studies. Progress in these various areas has, in turn, led to exciting new developments in the modeling area where Data Assimilation, and Weather Forecast models are showing dramatic improvements after the assimilation of observed rainfall fields.

  10. Development of the Application techniques for KMA dual-pol. radar network in Korea

    NASA Astrophysics Data System (ADS)

    Suk, Mi-Kyung; Nam, Kyung-Yeub; Jung, Sung-A.; Ko, Jeong-Seok

    2016-04-01

    Korea is located between the Eurasian continent and Northwestern pacific. So East Asian Monsoon affects the country every season and every year with the rainy season (Chang-ma front), convective stroms, snow storms, and sometimes typhoons. Korea Meteorological Administration (KMA) has been operating many kinds of meteorological observation networks, including 10 operational radars and 1 testbed radar. Weather Radar Center (WRC) of Korea Meteorological Administration (KMA) performs a task of development and application of cross governmental dual-pol. radar harmonization for the effective use of the national resources from 2013 since the tri-agencies (KMA, Ministry of Land, Infrastructure and Transport, Ministry of National Defense) singed the MOU for the co-utilization of cross governmental dual-pol. radar. This task develops the techniques of the high-quality data processing, the support of the forecasting, etc. The techniques of the high-quality data processing are the quality control for the removal of non-meteorological echoes, the classification of the hydrometeors. The techniques for support of the forecasting are the computation and verification of the rainfall estimation of dual-pol. and single-pol. radars, etc. And it is developed the application techniques by using Yong-In Testbed dual-pol. radar, the merged rainfall field of the radars and the satellites, etc. Further works are the computation of the high-resolution 3-dimensional wind field, the quantitative precipitation forecasting, the development of the application and the information service techniques for the hydrology, climate, industry, aviation for the prevention techniques against the severe weather by using multi-wavelengths ( X, C, S-band radars) of the cross governments, etc.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  12. Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar. Thesis Technical Report No. 20

    NASA Technical Reports Server (NTRS)

    Lai, Jonathan Y.

    1994-01-01

    This dissertation focuses on the signal processing problems associated with the detection of hazardous windshears using airborne Doppler radar when weak weather returns are in the presence of strong clutter returns. In light of the frequent inadequacy of spectral-processing oriented clutter suppression methods, we model a clutter signal as multiple sinusoids plus Gaussian noise, and propose adaptive filtering approaches that better capture the temporal characteristics of the signal process. This idea leads to two research topics in signal processing: (1) signal modeling and parameter estimation, and (2) adaptive filtering in this particular signal environment. A high-resolution, low SNR threshold maximum likelihood (ML) frequency estimation and signal modeling algorithm is devised and proves capable of delineating both the spectral and temporal nature of the clutter return. Furthermore, the Least Mean Square (LMS) -based adaptive filter's performance for the proposed signal model is investigated, and promising simulation results have testified to its potential for clutter rejection leading to more accurate estimation of windspeed thus obtaining a better assessment of the windshear hazard.

  13. Comparison of atmospheric instability indices derived from radiosonde observations and precipitation values measured with a weather radar and a rain gauge network in Sao Paulo, Brazil.

    NASA Astrophysics Data System (ADS)

    Alves, Mauro; Martin, Inacio; Shkevov, Rumen; Gusev, Anatoly; De Abreu, Alessandro

    2016-07-01

    Radio soundings are carried out daily in more than 800 stations throughout the world. The data collected in the soundings are used in many meteorological applications such as numerical weather prediction and climate models. Despite the relatively large number of sounding stations, they are unevenly distributed over the globe. It is generally assumed that the desired distance between stations is 300 km. In this study, we performed a comparison of 20 soundings of two stations located 85 km apart (State of São Paulo, Brazil; 23.511811° S, 46.637528° W, and 23.212578° S, 45.866581° W) to determine whether there is a concordance between atmospheric instability indices derived from the data collected by soundings at the these different locations. Additionally, precipitation data obtained by a meteorological radar and a rain gauge network during the same period as the soundings are compared to the stability indices to establish a correlation between precipitation values and these indices.

  14. Values of Deploying a Compact Polarimetric Radar to Monitor Extreme Precipitation in a Mountainous Area: Mineral County, Colorado

    NASA Astrophysics Data System (ADS)

    Cheong, B. L.; Kirstetter, P. E.; Yu, T. Y.; Busto, J.; Speeze, T.; Dennis, J.

    2015-12-01

    Precipitation in mountainous regions can trigger flash floods and landslides especially in areas affected by wildfire. Because of the small space-time scales required for observation, they remain poorly observed. A light-weighted X-band polarimetric radar can rapidly respond to the situation and provide continuous rainfall information with high resolution for flood forecast and emergency management. A preliminary assessment of added values to the operational practice in Mineral county, Colorado was performed in Fall 2014 and Summer 2015 with a transportable polarimetric radar deployed at the Lobo Overlook. This region is one of the numerous areas in the Rocky Mountains where the WSR-88D network does not provide sufficient weather coverage due to blockages, and the limitations have impeded forecasters and local emergency managers from making accurate predictions and issuing weather warnings. High resolution observations were collected to document the precipitation characteristics and demonstrate the added values of deploying a small weather radar in such context. The analysis of the detailed vertical structure of precipitation explain the decreased signal sampled by the operational radars. The specific microphysics analyzed though polarimetry suggest that the operational Z-R relationships may not be appropriate to monitor severe weather over this wildfire affected region. Collaboration with the local emergency managers and the National Weather Service shows the critical value of deploying mobile, polarimetric and unmanned radars in complex terrain. Several selected cases are provided in this paper for illustration.

  15. Observations of the marine environment from spaceborne side-looking real aperture radars

    NASA Technical Reports Server (NTRS)

    Kalmykov, A. I.; Velichko, S. A.; Tsymbal, V. N.; Kuleshov, Yu. A.; Weinman, J. A.; Jurkevich, I.

    1993-01-01

    Real aperture, side looking X-band radars have been operated from the Soviet Cosmos-1500, -1602, -1766 and Ocean satellites since 1984. Wind velocities were inferred from sea surface radar scattering for speeds ranging from approximately 2 m/s to those of hurricane proportions. The wind speeds were within 10-20 percent of the measured in situ values, and the direction of the wind velocity agreed with in situ direction measurements within 20-50 deg. Various atmospheric mesoscale eddies and tropical cyclones were thus located, and their strengths were inferred from sea surface reflectivity measurements. Rain cells were observed over both land and sea with these spaceborne radars. Algorithms to retrieve rainfall rates from spaceborne radar measurements were also developed. Spaceborne radars have been used to monitor various marine hazards. For example, information derived from those radars was used to plan rescue operations of distressed ships trapped in sea ice. Icebergs have also been monitored, and oil spills were mapped. Tsunamis produced by underwater earthquakes were also observed from space by the radars on the Cosmos 1500 series of satellites. The Cosmos-1500 satellite series have provided all weather radar imagery of the earths surface to a user community in real time by means of a 137.4 MHz Automatic Picture Transmission channel. This feature enabled the radar information to be used in direct support of Soviet polar maritime activities.

  16. Rainfall simulation in education

    NASA Astrophysics Data System (ADS)

    Peters, Piet; Baartman, Jantiene; Gooren, Harm; Keesstra, Saskia

    2016-04-01

    Rainfall simulation has become an important method for the assessment of soil erosion and soil hydrological processes. For students, rainfall simulation offers an year-round, attractive and active way of experiencing water erosion, while not being dependent on (outdoors) weather conditions. Moreover, using rainfall simulation devices, they can play around with different conditions, including rainfall duration, intensity, soil type, soil cover, soil and water conservation measures, etc. and evaluate their effect on erosion and sediment transport. Rainfall simulators differ in design and scale. At Wageningen University, both BSc and MSc student of the curriculum 'International Land and Water Management' work with different types of rainfall simulation devices in three courses: - A mini rainfall simulator (0.0625m2) is used in the BSc level course 'Introduction to Land Degradation and Remediation'. Groups of students take the mini rainfall simulator with them to a nearby field location and test it for different soil types, varying from clay to more sandy, slope angles and vegetation or litter cover. The groups decide among themselves which factors they want to test and they compare their results and discuss advantage and disadvantage of the mini-rainfall simulator. - A medium sized rainfall simulator (0.238 m2) is used in the MSc level course 'Sustainable Land and Water Management', which is a field practical in Eastern Spain. In this course, a group of students has to develop their own research project and design their field measurement campaign using the transportable rainfall simulator. - Wageningen University has its own large rainfall simulation laboratory, in which a 15 m2 rainfall simulation facility is available for research. In the BSc level course 'Land and Water Engineering' Student groups will build slopes in the rainfall simulator in specially prepared containers. Aim is to experience the behaviour of different soil types or slope angles when (heavy) rain

  17. Forecast of muddy floods using high-resolution radar precipitation forcasting data and erosion modelling

    NASA Astrophysics Data System (ADS)

    Hänsel, Phoebe; Schindewolf, Marcus; Schmidt, Jürgen

    2016-04-01

    In the federal province of Saxony, Eastern Germany, almost 60 % of the agricultural land is endangered by erosion processes, mainly caused by heavy rainfall events. Beside the primary impact of soil loss and decreasing soil fertility, erosion can cause significant effects if transported sediments are entering downslope settlements, infrastructure or traffic routes. Available radar precipitation data are closing the gap between the conventional rainfall point measurements and enable the nationwide rainfall distribution with high spatial and temporal resolution. By means of the radar precipitation data of the German Weather Service (DWD), high-resolution radar-based rainfall data totals up to 5 minute time steps are possible. The radar data are visualised in a grid-based hourly precipitation map. In particular, the daily and hourly precipitation maps help to identify regions with heavy rainfall and possible erosion events. In case of an erosion event on agricultural land, these areas are mapped with an unmanned airborne vehicle (UAV). The camera-equipped UAV delivers high-resolution images of the erosion event, that allow the generation of high-resolution orthophotos. By the application of the high-resolution radar precipitation data as an input for the process-based soil loss and deposition model EROSION 3D, these images are for validation purposes. Future research is focused on large scale soil erosion modelling with the help of the radar forecasting product and an automatic identification of sediment pass over points. The study will end up with an user friendly muddy flood warning tool, which allows the local authorities to initiate immediate measures in order to prevent severe damages in settlements, infrastructure or traffic routes.

  18. On the sensitivity of urban hydrodynamic modelling to rainfall spatial and temporal resolution

    NASA Astrophysics Data System (ADS)

    Bruni, G.; Reinoso, R.; van de Giesen, N. C.; Clemens, F. H. L. R.; ten Veldhuis, J. A. E.

    2014-06-01

    Cities are increasingly vulnerable to floods generated by intense rainfall, because of their high degree of imperviousness, implementation of infrastructures, and changes in precipitation patterns due to climate change. Accurate information of convective storm characteristics at high spatial and temporal resolution is a crucial input for urban hydrological models to be able to simulate fast runoff processes and enhance flood prediction. In this paper, a detailed study of the sensitivity of urban hydrological response to high resolution radar rainfall was conducted. Rainfall rates derived from X-band dual polarimetric weather radar for four rainstorms were used as input into a detailed hydrodynamic sewer model for an urban catchment in Rotterdam, the Netherlands. Dimensionless parameters were derived to compare results between different storm conditions and to describe the effect of rainfall spatial resolution in relation to storm and hydrodynamic model properties: rainfall sampling number (rainfall resolution vs. storm size), catchment sampling number (rainfall resolution vs. catchment size), runoff and sewer sampling number (rainfall resolution vs. runoff and sewer model resolution respectively). Results show catchment smearing effect for rainfall resolution approaching half the catchment size, i.e. for catchments sampling numbers greater than 0.5 averaged rainfall volumes decrease about 20%. Moreover, deviations in maximum water depths, form 10 to 30% depending on the storm, occur for rainfall resolution close to storm size, describing storm smearing effect due to rainfall coarsening. Model results also show the sensitivity of modelled runoff peaks and maximum water depths to the resolution of the runoff areas and sewer density respectively. Sensitivity to temporal resolution of rainfall input seems low compared to spatial resolution, for the storms analysed in this study. Findings are in agreement with previous studies on natural catchments, thus the sampling

  19. Comparison Between GOES-12 Overshooting-Top Detections, WSR-88D Radar Reflectivity, and Severe Storm Reports

    NASA Technical Reports Server (NTRS)

    Dworak, Richard; Bedka, Kristopher; Brunner, Jason; Feltz, Wayne

    2012-01-01

    Studies have found that convective storms with overshooting-top (OT) signatures in weather satellite imagery are often associated with hazardous weather, such as heavy rainfall, tornadoes, damaging winds, and large hail. An objective satellite-based OT detection product has been developed using 11-micrometer infrared window (IRW) channel brightness temperatures (BTs) for the upcoming R series of the Geostationary Operational Environmental Satellite (GOES-R) Advanced Baseline Imager. In this study, this method is applied to GOES-12 IRW data and the OT detections are compared with radar data, severe storm reports, and severe weather warnings over the eastern United States. The goals of this study are to 1) improve forecaster understanding of satellite OT signatures relative to commonly available radar products, 2) assess OT detection product accuracy, and 3) evaluate the utility of an OT detection product for diagnosing hazardous convective storms. The coevolution of radar-derived products and satellite OT signatures indicates that an OT often corresponds with the highest radar echo top and reflectivity maximum aloft. Validation of OT detections relative to composite reflectivity indicates an algorithm false-alarm ratio of 16%, with OTs within the coldest IRW BT range (less than 200 K) being the most accurate. A significant IRW BT minimum typically present with an OT is more often associated with heavy precipitation than a region with a spatially uniform BT. Severe weather was often associated with OT detections during the warm season (April September) and over the southern United States. The severe weather to OT relationship increased by 15% when GOES operated in rapid-scan mode, showing the importance of high temporal resolution for observing and detecting rapidly evolving cloud-top features. Comparison of the earliest OT detection associated with a severe weather report showed that 75% of the cases occur before severe weather and that 42% of collocated severe

  20. The Severe Weather Outbreak of 10 November 2002: Lightning and Radar Analysis of Storms in the Deep South

    NASA Technical Reports Server (NTRS)

    Buechler, D. E.; McCaul, E. W., Jr.; Goodman, S. J.; Blakeslee, R. J.; Bailey, J. C.; Gatlin, P.

    2004-01-01

    On the afternoon and evening of 10 November 2002, the Midwest and Deep South were struck by a major outbreak of severe storms that produced some 80 tornadoes. In terms of number of tornadoes, this was the largest outbreak in the United States since November 1992. Some 32 of the tornadoes occurred in Tennessee, Mississippi, Alabama and Georgia, including several long-track killers. We use the North Alabama Lightning Mapping Array (LMA) and other data sources to perform a comprehensive analysis of the structure and evolution of the outbreak. Most of the Southern tornadoes occurred in isolated, fast-moving supercell storms that formed in warm, moist air ahead of a major cold front. Storms tended to form in lines parallel to storm cell motion, resulting in many communities being hit multiple times by severe storms that evening. Supercells in Tennessee produced numerous strong tornadoes with short to medium-length track paths, while the supercells further south produced several very long-track tornadoes. Radar data indicate that the Tennessee storms tended to split frequently, apparently limiting their ability to sustain long-lived tornadoes, while storms further south split at most one time. The differences between these storms appear to be related to the presence of stronger jetstream winds in Tennessee relative to those present in Mississippi, Alabama and Georgia. LMA-derived flash rates associated with most of the supercell storm cores were about 1-2 flashes per second. Rapid increases in lightning rates (or "jumps") occurred prior to tornado touchdown in many instances. Lightning "holes" (lightning-free regions associated with the echo-free vault) occurred in two of the Tennessee supercells. The complexity of the relationship between lightning and storm severity is revealed by the behavior of one Alabama supercell, which produced a peak flash rate of nearly 14 flashes per second, well after the end of its long-track tornado, while interacting and ultimately merging

  1. Stratiform and Convective Precipitation Observed by Multiple Radars during the DYNAMO/AMIE Experiment

    SciTech Connect

    Deng, Min; Kollias, Pavlos; Feng, Zhe; Zhang, Chidong; Long, Charles N.; Kalesse, Heike; Chandra, Arunchandra; Kumar, Vickal; Protat, Alain

    2014-11-01

    The motivation for this research is to develop a precipitation classification and rain rate estimation method using cloud radar-only measurements for Atmospheric Radiation Measurement (ARM) long-term cloud observation analysis, which are crucial and unique for studying cloud lifecycle and precipitation features under different weather and climate regimes. Based on simultaneous and collocated observations of the Ka-band ARM zenith radar (KAZR), two precipitation radars (NCAR S-PolKa and Texas A&M University SMART-R), and surface precipitation during the DYNAMO/AMIE field campaign, a new cloud radar-only based precipitation classification and rain rate estimation method has been developed and evaluated. The resulting precipitation classification is equivalent to those collocated SMART-R and S-PolKa observations. Both cloud and precipitation radars detected about 5% precipitation occurrence during this period. The convective (stratiform) precipitation fraction is about 18% (82%). The 2-day collocated disdrometer observations show an increased number concentration of large raindrops in convective rain compared to dominant concentration of small raindrops in stratiform rain. The composite distributions of KAZR reflectivity and Doppler velocity also show two distinct structures for convective and stratiform rain. These indicate that the method produces physically consistent results for two types of rain. The cloud radar-only rainfall estimation is developed based on the gradient of accumulative radar reflectivity below 1 km, near-surface Ze, and collocated surface rainfall (R) measurement. The parameterization is compared with the Z-R exponential relation. The relative difference between estimated and surface measured rainfall rate shows that the two-parameter relation can improve rainfall estimation.

  2. GPM Movie of Souledor's Rainfall Structure

    NASA Video Gallery

    On Aug. 5, the GPM satellite data was used to make a 3-D vertical structure of rainfall within Soudelor. Some storms examined with GPM's radar reached heights of over 12.9 km (about 8 miles) and we...

  3. TRMM Data from the Goddard Earth Sciences (GES) DISC DAAC: Tropical Rainfall Measuring Mission (TRMM)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Tropical rainfall affects the lives and economies of a majority of the Earth's population. Tropical rain systems, such as hurricanes, typhoons, and monsoons, are crucial to sustaining the livelihoods of those living in the tropics. Excess rainfall can cause floods and great property and crop damage, whereas too little rainfall can cause drought and crop failure. The latent heat release during the process of precipitation is a major source of energy that drives the atmospheric circulation. This latent heat can intensify weather systems, affecting weather thousands of kilometers away, thus making tropical rainfall an important indicator of atmospheric circulation and short-term climate change. The Tropical Rainfall Measuring Mission (TRMM), jointly sponsored by the National Aeronautics and Space Administration (NASA) of the United States and the National Space Development Agency (NASDA) of Japan, provides visible, infrared, and microwave observations of tropical and subtropical rain systems. The satellite observations are complemented by ground radar and rain gauge measurements to validate satellite rain estimation techniques. Goddard Space Flight Center's involvement includes the observatory, four instruments, integration and testing of the observatory, data processing and distribution, and satellite operations. TRMM has a design lifetime of three years. It is currently in its fifth year of operation. Data generated from TRMM and archived at the GES DAAC are useful not only for hydrologists, atmospheric scientists, and climatologists, but also for the health community studying infectious diseases, the ocean research community, and the agricultural community.

  4. A semi-urban case study of small scale variability of rainfall and run-off, with C- and X-band radars and the fully distributed hydrological model Multi-Hydro

    NASA Astrophysics Data System (ADS)

    Alves de Souza, Bianca; da Silva Rocha Paz, Igor; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    The complexity of urban hydrology results both from that of urban systems and the extreme rainfall variability. The latter can display strongly localised rain cells that can be extremely damaging when hitting vulnerable parts of urban systems. This paper investigates this complexity on a semi-urban sub-catchment - located in Massy (South of Paris, France) - of the Bievre river, which is known for its frequent flashfloods. Advanced geo-processing techniques were used to find the ideal pixel size for this 6.326km2 basin. C-band and X-band radar data are multifractally downscaled at various resolutions and input to the fully distributed hydrological model Multi-Hydro. The latter has been developed at Ecole des Ponts ParisTech. It integrates validated modules dealing with surface flow, saturated and unsaturated surface flow, and sewer flow. The C-band radar is located in Trappes, approx. 21km East of the catchment, is operated by Méteo-France and has a resolution of 1km x 1km x 5min. The X-band radar operated by Ecole des Ponts Paris Tech on its campus has a resolution of 125m x 125m x 3.4min. The performed multifractal downscaling enables both the generation of large ensemble realizations and easy change of resolution (e.g. down to 10 m in the present study). This in turn allows a detailed analysis of the impacts of small scale variability and the required resolution to obtain accurate simulations, therefore predictions. This will be shown on two rainy episodes over the chosen sub-catchment of the Bievre river.

  5. Towards Near Real-time Convective Rainfall Observations over Kenya

    NASA Astrophysics Data System (ADS)

    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

    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

  6. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    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 objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  7. Understanding and optimizing microstrip patch antenna cross polarization radiation on element level for demanding phased array antennas in weather radar applications

    NASA Astrophysics Data System (ADS)

    Vollbracht, D.

    2015-11-01

    The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation

  8. MJO modulation on diurnal rainfall over West Java during pre-monsoon and strong El Niño periods

    NASA Astrophysics Data System (ADS)

    Yulihastin, E.; Trismidianto; Satyawardhana, H.; Nugroho, G. A.

    2017-01-01

    This study was conducted to determine the MJO modulation ondiurnal rainfall in West Java during the pre-monsoon and strong El Niño periods in 2015 over West Java. The data used is a combination of satellite data, reanalysis data, radar stations data, and numerical weather prediction of Weather Research and Forecasting (WRF) data with spatial resolution of 5 km. The results confirmed that the strong MJO in 4 and 5 phases has modulated the amplitude of diurnal rainfall increase significantly over West Java in phase of lag+1. Modulation on diurnal cycle of rainfall was also indicated by the persistence of the rainfall and the formation of two peaks of maximum rainfall in the afternoon and early morning. In addition, modulation of rainfall for the southern part of Java was 50% greater than the north. Moreover, the MJO modulation mechanism was characterized by the formation of an active and extending of Meso-scale Convective System (MCS) which has a cycle of up to 12 hours and persistent from November 7-9 over West Java.

  9. Changes in the TRMM Version-5 and Version-6 Precipitation Radar Products Due to Orbit Boost

    NASA Technical Reports Server (NTRS)

    Liao, Liang; Meneghini, Robert

    2010-01-01

    The performance of the version-5 and version-6 Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) products before and after the satellite orbit boost is assessed through a series of comparisons with Weather Surveillance Radar (WSR)-88D ground-based radar in Melbourne, Florida. Analysis of the comparisons of radar reflectivity near the storm top from the ground radar and both versions of the PR indicates that the PR bias relative to the WSR radar at Melbourne is on the order of 1dB for both pre- and post-boost periods, indicating that the PR products maintain accurate calibration after the orbit boost. Comparisons with the WSR-88D near-surface reflectivity factors indicate that both versions of the PR products accurately correct for attenuation in stratiform rain. However, in convective rain, both versions exhibit negative biases in the near-surface radar reflectivity with version-6 products having larger negative biases than version-5. Rain rate comparisons between the ground and space radars show similar characteristics

  10. Weather Specialist/Aerographer's Mate.

    ERIC Educational Resources Information Center

    Chanute AFB Technical Training Center, IL.

    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…

  11. Constraining frequency-magnitude-area relationships for rainfall and flood discharges using radar-derived precipitation estimates: example applications in the Upper and Lower Colorado River basins, USA

    NASA Astrophysics Data System (ADS)

    Orem, Caitlin A.; Pelletier, Jon D.

    2016-11-01

    Flood-envelope curves (FECs) are useful for constraining the upper limit of possible flood discharges within drainage basins in a particular hydroclimatic region. Their usefulness, however, is limited by their lack of a well-defined recurrence interval. In this study we use radar-derived precipitation estimates to develop an alternative to the FEC method, i.e., the frequency-magnitude-area-curve (FMAC) method that incorporates recurrence intervals. The FMAC method is demonstrated in two well-studied US drainage basins, i.e., the Upper and Lower Colorado River basins (UCRB and LCRB, respectively), using Stage III Next-Generation-Radar (NEXRAD) gridded products and the diffusion-wave flow-routing algorithm. The FMAC method can be applied worldwide using any radar-derived precipitation estimates. In the FMAC method, idealized basins of similar contributing area are grouped together for frequency-magnitude analysis of precipitation intensity. These data are then routed through the idealized drainage basins of different contributing areas, using contributing-area-specific estimates for channel slope and channel width. Our results show that FMACs of precipitation discharge are power-law functions of contributing area with an average exponent of 0.82 ± 0.06 for recurrence intervals from 10 to 500 years. We compare our FMACs to published FECs and find that for wet antecedent-moisture conditions, the 500-year FMAC of flood discharge in the UCRB is on par with the US FEC for contributing areas of ˜ 102 to 103 km2. FMACs of flood discharge for the LCRB exceed the published FEC for the LCRB for contributing areas in the range of ˜ 103 to 104 km2. The FMAC method retains the power of the FEC method for constraining flood hazards in basins that are ungauged or have short flood records, yet it has the added advantage that it includes recurrence-interval information necessary for estimating event probabilities.

  12. Wageningen Urban Rainfall Experiment 2014 (WURex14): Experimental setup and preliminary results

    NASA Astrophysics Data System (ADS)

    van Leth, Thomas C.; Uijlenhoet, Remko; Overeem, Aart; Leijnse, Hidde; Hazenberg, Pieter; Berne, Alexis

    2016-04-01

    Microwave links from cellular communication networks have been shown to be able to provide valuable information concerning the space-time variability of rainfall. In particular over urban areas, where network densities are generally high, they have the potential to complement existing dedicated infrastructure to measure rainfall (gauges, radars). In addition, microwave links provide a great opportunity for ground-based rainfall measurement for those land surface areas of the world where gauges and radars are generally lacking. Such information is not only crucial for water management and agriculture, but also for instance for ground validation of space-borne rainfall estimates such as those provided by the GPM (Global Precipitation Measurement) mission. WURex14 is dedicated to address several errors and uncertainties associated with such quantitative precipitation estimates in detail. The core of the experiment is provided by three co-located microwave links installed between two major buildings on the Wageningen University campus, approximately 2 km apart: a 38 GHz commercial microwave link, provided by T-Mobile NL, and 26 GHz and 38 GHz (dual-polarization) research microwave links from RAL. Transmitting and receiving antennas have been attached to masts installed on the roofs of the two buildings, about 30 m above the ground. This setup has been complemented with a Scintec infrared Large-Aperture Scintillometer, installed over the same path, as well as 5 Parsivel optical disdrometers and an automated rain gauge positioned at several locations along the path. Temporal sampling of the received signals was performed at a rate of 20 Hz. The setup is being monitored by time-lapse cameras to assess the state of the antennas as well as the atmosphere. Finally, data is available from the KNMI weather radars and an automated weather station situated just outside Wageningen. The experiment has been active between August 2014 and December 2015. We give a global overview of

  13. Effects of Tunable Data Compression on Geophysical Products Retrieved from Surface Radar Observations with Applications to Spaceborne Meteorological Radars

    NASA Technical Reports Server (NTRS)

    Gabriel, Philip M.; Yeh, Penshu; Tsay, Si-Chee

    2013-01-01

    This paper presents results and analyses of applying an international space data compression standard to weather radar measurements that can easily span 8 orders of magnitude and typically require a large storage capacity as well as significant bandwidth for transmission. By varying the degree of the data compression, we analyzed the non-linear response of models that relate measured radar reflectivity and/or Doppler spectra to the moments and properties of the particle size distribution characterizing clouds and precipitation. Preliminary results for the meteorologically important phenomena of clouds and light rain indicate that for a 0.5 dB calibration uncertainty, typical for the ground-based pulsed-Doppler 94 GHz (or 3.2 mm, W-band) weather radar used as a proxy for spaceborne radar in this study, a lossless compression ratio of only 1.2 is achievable. However, further analyses of the non-linear response of various models of rainfall rate, liquid water content and median volume diameter show that a lossy data compression ratio exceeding 15 is realizable. The exploratory analyses presented are relevant to future satellite missions, where the transmission bandwidth is premium and storage requirements of vast volumes of data, potentially problematic.

  14. GMS-based"Future Time" Rainfall Data Assimilation for Mesoscale Weather Prediction over Korean Peninsula and Future Prospects with GPM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Ou, Mi-Lim

    2004-01-01

    This study examines the use of satellite-derived nowcasted (short-term forecasted) rainfall over 3-hour time periods to gain an equivalent time increment in initializing a nonhydrostatic mesoscale model used for predicting convective rainfall events over the Korean peninsula. Infrared (IR) window measurements from the Japanese Geostationary Meteorological Satellite (GMS) are used to specify latent heating for a spinup period of the model - but in future time -- thus initializing in advance of actual time in the framework of a prediction scenario. The main scientific objective of the study is to investigate the strengths and weaknesses of this approach insofar as data assimilation, in which the nowcasted assimilation data are derived independently of the prognostic model itself. Although there have been various recent improvements in formulating the dynamics, thermodynamics, and microphysics of mesoscale models, as well as computer advances which allow the use of high resolution cloud-resolving grids and explicit latent heating over regional domains, spinup remains at the forefront of unresolved mesoscale modeling problems. In general, non-realistic spinup limits the skill in predicting the spatial-temporal distribution of convection and precipitation, primarily in the early hours of a. forecast, stemming from standard prognostic variables not representing the initial diabatic heating field produced by the ambient convection and cloud fields. The long-term goal of this research is to improve short-range (12-hour) quantitative precipitation forecasting (QPF) over the Korean peninsula through the use of innovative data assimilation methods based on geosynchronous satellite measurements. As a step in ths direction, a non-standard data assimilation experiment in conjunction with GMS-retrieved nowcasted rainfall information introduced to the mesoscale model is conducted. The 3-hourly precipitation forecast information is assimilated through nudging the associated

  15. LDAR observations of a developing thunderstorm correlated with field mill, ground strike location, and weather radar data including the first report of the design and capabilities of a new, time-of-arrival Ground-strike Location System (GSLS)

    NASA Technical Reports Server (NTRS)

    Poehler, H. A.

    1978-01-01

    An experiment designed to observe and measure a thunderstorm prior to, during, and after its development over the Kennedy Space Center was successful. Correlated measurements of airborne field strength, ground-based field strength, LDAR lightning discharge location in the clouds, weather radar percipitation echoes, plus ground strike location with the new KSC Ground Strike Location System (GSLS) were gathered, and reported. This test marks the first operational use of the GSLS System, and this report contains the first report of its design and capabilities.

  16. An Experimental Study of the Rainfall Variability Within TRMM/GPM Precipitation Radar and Microwave Sensor Instantaneous Field of View During MC3E

    NASA Technical Reports Server (NTRS)

    Tokay, Ali; Petersen, Arthur; Gatlin, Patrick N.; Wingo, Matt; Wolff, David B.; Carey, Lawrence D.

    2011-01-01

    Dual tipping bucket gauges were operated at 16 sites in support of ground based precipitation measurements during Mid-latitude Continental Convective Clouds Experiment (MC3E). The experiment is conducted in North Central Oklahoma from April 22 through June 6, 2011. The gauge sites were distributed around Atmospheric Radiation Measurement (ARM) Climate Research facility where the minimum and maximum separation distances ranged from 1 to 12 km. This study investigates the rainfall variability by employing the stretched exponential function. It will focus on the quantitative assessment of the partial beam of the experiment area in both convective and stratiform rain. The parameters of the exponential function will also be determined for various events. This study is unique for two reasons. First is the existing gauge setup and the second is the highly convective nature of the events with rain rates well above 100 mm h-1 for 20 minutes. We will compare the findings with previous studies.

  17. An Experimental Study of the Rainfall Variability Within TRMM/GPM Precipitation Radar and Microwave Sensor Instantaneous Field of View During MC3E

    NASA Technical Reports Server (NTRS)

    Tokay, Ali; Petersen, Walter Arthur; Gatlin, Patrick N.; Wingo, Matt; Wolff, David B.; Carey, Lawrence D.

    2011-01-01

    Dual tipping bucket gauges were operated at 16 sites in support of ground based precipitation measurements during Mid-latitude Continental Convective Clouds Experiment (MC3E). The experiment is conducted in North Central Oklahoma from April 22 through June 6, 2011. The gauge sites were distributed around Atmospheric Radiation Measurement (ARM) Climate Research facility where the minimum and maximum separation distances ranged from 1 to 12 km. This study investigates the rainfall variability by employing the stretched exponential function. It will focus on the quantitative assessment of the partial beam of the experiment area in both convective and stratiform rain. The parameters of the exponential function will also be determined for various events. This study is unique for two reasons. First is the existing gauge setup and the second is the highly convective nature of the events with rain rates well above 100 mm/h for 20 minutes. We will compare the findings with previous studies.

  18. Dynamical linkage of tropical and subtropical weather systems to the intraseasonal oscillations of the Indian summer monsoon rainfall. Part II: Simulations in the ENSEMBLES project

    NASA Astrophysics Data System (ADS)

    Ma, Shujie; Rodó, Xavier; Song, Yongjia; Cash, Benjamin A.

    2012-09-01

    We assess the ability of individual models (single-model ensembles) and the multi-model ensemble (MME) in the European Union-funded ENSEMBLES project to simulate the intraseasonal oscillations (ISOs; specifically in 10-20-day and 30-50-day frequency bands) of the Indian summer monsoon rainfall (ISMR) over the Western Ghats (WG) and the Bay of Bengal (BoB), respectively. This assessment is made on the basis of the dynamical linkages identified from the analysis of observations in a companion study to this work. In general, all models show reasonable skill in simulating the active and break cycles of the 30-50-day ISOs over the Indian summer monsoon region. This skill is closely associated with the proper reproduction of both the northward propagation of the intertropical convergence zone (ITCZ) and the variations of monsoon circulation in this band. However, the models do not manage to correctly simulate the eastward propagation of the 30-50-day ISOs in the western/central tropical Pacific and the eastward extension of the ITCZ in a northwest to southeast tilt. This limitation is closely associated with a limited capacity of models to accurately reproduce the magnitudes of intraseasonal anomalies of both the ITCZ in the Asian tropical summer monsoon regions and trade winds in the tropical Pacific. Poor reproduction of the activity of the western Pacific subtropical high on intraseasonal time scales also amplify this limitation. Conversely, the models make good reproduction of the WG 10-20-day ISOs. This success is closely related to good performance of the models in the representation of the northward propagation of the ITCZ, which is partially promoted by local air-sea interactions in the Indian Ocean in this higher-frequency band. Although the feature of westward propagation is generally represented in the simulated BoB 10-20-day ISOs, the air-sea interactions in the Indian Ocean are spuriously active in the models. This leads to active WG rainfall, which is not

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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

  20. Effect of Precipitation to the Wind Retrieval from Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Yu, Shui; Yang, Jingsong; He, Shuangyan; He, Zhiguo; Ren, Lin

    2016-08-01

    As one of the most powerful air-sea interaction in the weather system, typhoon always accompany with a wide range of heavy rainfall. Synthetic Aperture Radar(SAR) plays an important role in typhoon wind field retrieval, because it can work all-day, all-weather and has high spatial resolution. But due to the influence of the rainfall on the radar signal, the inversion precision of sea surface wind field will decline. With the exploration of high wind speed inversion model, much more researchers focus on the influence of large precipitation to the wind field retrieval. Researchers have proposed many different rain effect models applied to scatterometer data, but it is not sure weather they can also used on SAR data.In this paper, one C band scatterometer rain effect model proposed by Congling Nie and David G. Long (TGRS 2007) was applied on typhoon Rammasun RADARSAT-2 ASAR data. Combined with the sea wind direction information from European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis data, high accuracy and high-resolution wind field was obtained by using geophysical model function CMOD5.Then the result was validated with wind field retrieved from VH polarization data using C-band Cross-Polarization Ocean (C-2PO) model (Biao Zhang and William Perrie, AMS, 2012), the comparison showed that there still need further correction based on by Nie and Long's rain effect model.

  1. Model analysis of radar echo split observed in an artificial cloud seeding experiment

    NASA Astrophysics Data System (ADS)

    Masaki, Shimada; Kikuro, Tomine; Koji, Nishiyama

    2016-06-01

    An artificial cloud seeding experiment was performed over the Japan Sea in winter to show how massive seeding could be effective to mitigate heavy snowfall damage. The results showed that 20 min after cloud seeding, a portion of the radar echo beneath the seeding track was weakened to divide the radar echo into two parts. In order to analyze the results, a numerical simulation was conducted by using the Weather Research and Forecasting model verion 3.5.1. In this simulation, the seeding effects were represented as phenomena capable of changing rain particles by accreting cloud ice and snow to form graupel particles and by changing cloud liquid water to snow particles. The graupel particles fell rapidly, thus temporarily intensifying the rainfall, which subsequently decreased. Therefore, the weakened radar echo in the field experiment is deemed to have been caused by the increase in rapidly falling graupel particles.

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

    PubMed

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

    2008-04-01

    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).

  3. Identification of anomalous motion of thunderstorms using daily rainfall fields

    NASA Astrophysics Data System (ADS)

    Moral, Anna del; Llasat, María del Carmen; Rigo, Tomeu

    2017-03-01

    Most of the adverse weather phenomena in Catalonia (northeast Iberian Peninsula) are caused by convective events, which can produce heavy rains, large hailstones, strong winds, lightning and/or tornadoes. These thunderstorms usually have marked paths. However, their trajectories can vary sharply at any given time, completely changing direction from the path they have previously followed. Furthermore, some thunderstorms split or merge with each other, creating new formations with different behaviour. In order to identify the potentially anomalous movements that some thunderstorms make, this paper presents a two-step methodology using a database with 8 years of daily rainfall fields data for the Catalonia region (2008-2015). First, it classifies daily rainfall fields between days with "no rain", "non-potentially convective rain" and "potentially convective rain", based on daily accumulated precipitation and extension thresholds. Second, it categorises convective structures within rainfall fields and briefly identifies their main features, distinguishing whether there were any anomalous thunderstorm movements in each case. This methodology has been applied to the 2008-2015 period, and the main climatic features of convective and non-convective days were obtained. The methodology can be exported to other regions that do not have the necessary radar-based algorithms to detect convective cells, but where there is a good rain gauge network in place.

  4. Classification and correction of the radar bright band with polarimetric radar

    NASA Astrophysics Data System (ADS)

    Hall, Will; Rico-Ramirez, Miguel; Kramer, Stefan

    2015-04-01

    The annular region of enhanced radar reflectivity, known as the Bright Band (BB), occurs when the radar beam intersects a layer of melting hydrometeors. Radar reflectivity is related to rainfall through a power law equation and so this enhanced region can lead to overestimations of rainfall by a factor of up to 5, so it is important to correct for this. The BB region can be identified by using several techniques including hydrometeor classification and freezing level forecasts from mesoscale meteorological models. Advances in dual-polarisation radar measurements and continued research in the field has led to increased accuracy in the ability to identify the melting snow region. A method proposed by Kitchen et al (1994), a form of which is currently used operationally in the UK, utilises idealised Vertical Profiles of Reflectivity (VPR) to correct for the BB enhancement. A simpler and more computationally efficient method involves the formation of an average VPR from multiple elevations for correction that can still cause a significant decrease in error (Vignal 2000). The purpose of this research is to evaluate a method that relies only on analysis of measurements from an operational C-band polarimetric radar without the need for computationally expensive models. Initial results show that LDR is a strong classifier of melting snow with a high Critical Success Index of 97% when compared to the other variables. An algorithm based on idealised VPRs resulted in the largest decrease in error when BB corrected scans are compared to rain gauges and to lower level scans with a reduction in RMSE of 61% for rain-rate measurements. References Kitchen, M., R. Brown, and A. G. Davies, 1994: Real-time correction of weather radar data for the effects of bright band, range and orographic growth in widespread precipitation. Q.J.R. Meteorol. Soc., 120, 1231-1254. Vignal, B. et al, 2000: Three methods to determine profiles of reflectivity from volumetric radar data to correct

  5. Location-Based Rainfall Nowcasting Service for Public

    NASA Astrophysics Data System (ADS)

    Woo, Wang-chun

    2013-04-01

    The Hong Kong Observatory has developed the "Short-range Warning of Intense Rainstorms in Localized Systems (SWIRLS)", a radar-based rainfall nowcasting system originally to support forecasters in rainstorm warning and severe weather forecasting such as hail, lightning and strong wind gusts in Hong Kong. The system has since been extended to provide rainfall nowcast service direct for the public in recent years. Following the launch of "Rainfall Nowcast for the Pearl River Delta Region" service provided via a Geographical Information System (GIS) platform in 2008, a location-based rainfall nowcast service served through "MyObservatory", a smartphone app for iOS and Android developed by the Observatory, debuted in September 2012. The new service takes advantage of the capability of smartphones to detect own locations and utilizes the quantitative precipitation forecast (QPF) from SWIRLS to provide location-based rainfall nowcast to the public. The conversion of radar reflectivity data (at 2 or 3 km above ground) to rainfall in SWIRLS is based on the Z-R relationship (Z=aRb) with dynamical calibration of the coefficients a and b determined using real-time rain gauge data. Adopting the "Multi-scale Optical-flow by Variational Analysis (MOVA)" scheme to track the movement of radar echoes and Semi-Lagrangian Advection (SLA) scheme to extrapolate their movement, the system is capable of producing QPF for the next six hours in a grid of 480 x 480 that covers a domain of 256 km x 256 km once every 6 minutes. Referencing the closest point in a resampled 2-km grid over the territory of Hong Kong, a prediction as to whether there will be rainfall exceeding 0.5 mm in every 30 minute intervals for the next two hours at users' own or designated locations are made available to the users in both textual and graphical format. For those users who have opted to receive notifications, a message would pop up on the user's phone whenever rain is predicted in the next two hours in a user

  6. Calibration and Evaluation of a Flood Forecasting System: Utility of Numerical Weather Prediction Model, Data Assimilation and Satellite-based Rainfall

    NASA Astrophysics Data System (ADS)

    Yucel, Ismail; Onen, Alper; Yilmaz, Koray; Gochis, David

    2015-04-01

    A fully-distributed, multi-physics, multi-scale hydrologic and hydraulic modeling system, WRF-Hydro, is used to assess the potential for skillful flood forecasting based on precipitation inputs derived from the Weather Research and Forecasting (WRF) model and the EUMETSAT Multi-sensor Precipitation Estimates (MPEs). Similar to past studies it was found that WRF model precipitation forecast errors related to model initial conditions are reduced when the three dimensional atmospheric data assimilation (3DVAR) scheme in the WRF model simulations is used. The study then undertook a comparative evaluation of the impact of MPE versus WRF precipitation estimates, both with and without data assimilation, in driving WRF-Hydro simulated streamflow. Several flood events that occurred in the Black Sea region were used for testing and evaluation. Following model calibration, the WRF-Hydro system was capable of skillfully reproducing observed flood hydrographs in terms of the volume of the runoff produced and the overall shape of the hydrograph. Streamflow simulation skill was significantly improved for those WRF model simulations where storm precipitation was accurately depicted with respect to timing, location and amount. Accurate streamflow simulations were more evident in WRF model simulations where the 3DVAR scheme was used compared to when it was not used. Because of substantial dry bias feature of MPE, streamflow derived using this precipitation product is in general very poor. Overall, root mean squared errors for runoff were reduced by 22.2% when hydrological model calibration is performed with WRF precipitation. Errors were reduced by 36.9% (above uncalibrated model performance) when both WRF model data assimilation and hydrological model calibration was utilized. Our results also indicated that when assimilated precipitation and model calibration is performed jointly, the calibrated parameters at the gauged sites could be transferred to ungauged neighboring basins

  7. Influence of high resolution rainfall data on the hydrological response of urban flat catchments

    NASA Astrophysics Data System (ADS)

    Cristiano, Elena; ten Veldhuis, Marie-claire; van de Giesen, Nick

    2016-04-01

    In the last decades, cities have become more and more urbanized and population density in urban areas is increased. At the same time, due to the climate changes, rainfall events present higher intensity and shorter duration than in the past. The increase of imperviousness degree, due to urbanization, combined with short and intense rainfall events, determinates a fast hydrological response of the urban catchment and in some cases it can lead to flooding. Urban runoff processes are sensitive to rainfall spatial and temporal variability and, for this reason, high resolution rainfall data are required as input for the hydrological model. A better knowledge of the hydrological response of system can help to prevent damages caused by flooding. This study aims to evaluate the sensitivity of urban hydrological response to spatial and temporal rainfall variability in urban areas, focusing especially on understanding the hydrological behaviour in lowland areas. In flat systems, during intense rainfall events, the flow in the sewer network can be pressurized and it can change direction, depending on the setting of pumping stations and CSOs (combined sewer overflow). In many cases these systems are also looped and it means that the water can follow different paths, depending on the pipe filling process. For these reasons, hydrological response of flat and looped catchments is particularly complex and it can be difficult characterize and predict it. A new dual polarimetric X-band weather radar, able to measure rainfall with temporal resolution of 1 min and spatial resolution of 100mX100m, was recently installed in the city of Rotterdam (NL). With this instrument, high resolution rainfall data were measured and used, in this work, as input for the hydrodynamic model. High detailed, semi-distributed hydrodynamic models of some districts of Rotterdam were used to investigate the hydrological response of flat catchments to high resolution rainfall data. In particular, the

  8. Output tube emission characteristics of operational radars

    NASA Astrophysics Data System (ADS)

    Matheson, R. J.; Smilley, J. D.; Falcon, G. D.; Lawrence, V. S.

    1982-01-01

    Measurement of the emission spectra and other characteristics of many radars operating in the government frequency bands is described. The emission spectra of 19 different types of radars, selected to show the different emission spectrum characteristics produced by a variety of radar output tube technologies are presented. The radars include examples of ground based search, airport surveillance, weather, and height finding radars operating in L band, S band, or C band. The RSMS, contained within a mobile van, is described, along with the measurement techniques used for obtaining radar emission characteristics. The emission limits imposed by the Radar Spectrum Engineering Criteria (RSEC) are displayed with each emission spectrum.

  9. How Cities Make Their Own Weather

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall

    2004-01-01

    Urbanization is one of the extreme cases of land use change. Most of world's population has moved to urban areas. Although currently only 1.2% of the land is considered urban, the spatial coverage and density of cities are expected to rapidly increase in d e near future. It is estimated that by the year 2025, 60% of the world's population will live in cities. Human activity in urban environments also alters weather and climate processes. However, our understanding of urbanization on the total Earth-weather-climate system is incomplete. Recent literature continues to provide evidence that anomalies in precipitation exist over and downwind of major cities. Current and future research efforts are actively seeking to verify these literature findings and understand potential cause-effect relationships. The novelty of this study is that it utilizes rainfall data from multiple satellite data sources (e.g. TRMM precipitation radar, TRMM-geosynchronous-rain gauge merged product, and SSM/I) and ground-based measurements to identify spatial anomalies and temporal trends in precipitation for cities around the world. We will also present results from experiments using a regional atmospheric-land surface modeling system. Early results will be presented and placed within the context of weather prediction, climate assessment, and societal applications.

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

    NASA Technical Reports Server (NTRS)

    Marks, David A.; Wolff, David B.; Carey, Lawrence D.; Tokay, Ali

    2010-01-01

    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 capability to send and receive both horizontally and vertically oriented waves. These enhanced "dual-polarimetric" (DP) radars peer into precipitation and provide information on the size, shape, phase (liquid / frozen), and concentration of the falling particles (termed hydrometeors). This information is valuable for improved rain rate estimates, and for providing data on the release and absorption of heat in the atmosphere from condensation and evaporation (phase changes). The heating profiles in the atmosphere influence global circulation, and are a vital component in studies of Earth s changing climate. However, to provide the most accurate interpretation of radar data, the radar must be properly calibrated and data must be quality controlled (cleaned) to remove non-precipitation artifacts; both of which are challenging tasks for today s weather radar. The DP capability maximizes performance of these procedures using properties of the observed precipitation. In a notable paper published in 2005, scientists from the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) at the University of Oklahoma developed a method to calibrate radars using statistically averaged DP measurements within light rain. An additional publication by one of the same scientists at the National Severe Storms Laboratory (NSSL) in Norman, Oklahoma introduced several techniques to perform quality control of radar data using DP measurements. Following their lead, the Topical Rainfall Measuring Mission (TRMM) Satellite Validation Office at NASA s Goddard Space Flight Center has fine-tuned these methods for specific application to the weather radar at Kwajalein Island in the Republic of the Marshall Islands, approximately 2100 miles

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

    NASA Astrophysics Data System (ADS)

    Hardegree, S. P.

    2001-12-01

    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 than this in a given radar domain depending upon storm type and topography. As the original intent of this network was to support operational objectives of the Departments of Defense, Transportation and Commerce, the production of these data have been optimized for detection and mitigation of severe weather events that might result in flooding, destruction of property and loss of life. The primary hydrologic application has been river and flood forecast modeling by 13 NWS River Forecast Centers (RFC). As each RFC is responsible for a large river drainage, data processing and quality control of these data are geared toward optimization over a relatively large spatial domain (>100,000 km2). Use of these data for other hydrologic and natural resource applications is hampered by a lack of tools for data access and manipulation. NWRC has modified decoding and geo-referencing programs to facilitate ut