Sample records for weather radar rainfall

  1. 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 (OPERA) and extend this study to the entirety of Europe.

  2. Visualization of Local Rainfall from Weather Radar Measurements

    Microsoft Academic Search

    Thomas Gerstner; Dirk Meetschen; Susanne Crewell; Michael Griebel; Clemens Simmer

    Weather radars can measure the backscatter from rain drops in the atmosphere. A complete radar scan provides three-dimensional precipitation information. For the understanding of the underly- ing atmospheric processes the interactive visualization of these data sets is necessary. This task is, however, difficult due to the size and structure of the data and due to the neccessity of putting the

  3. Quantization analysis of weather radar data with synthetic rainfall

    Microsoft Academic Search

    M. Hammond; D. Han

    2008-01-01

    Quantization is a process by where continuous signals are transformed into discrete values. It is an important part of the\\u000a signal processing involved in using weather radar. Technological advances have made it easier to increase the number of quantization\\u000a levels, as witnessed by the replacement of a 3 bit system by an 8 bit system by the UK Meteorological Office. Research has

  4. Optoelectronic Multifractal Wavelet Analysis for Fast and Accurate Detection of Rainfall in Weather Radar Images

    Microsoft Academic Search

    Radhika Dahale

    2004-01-01

    In this thesis we propose an automated process for the removal of non-precipitation echoes present in weather radar signals and accurate detection of rainfall. The process employs multifractal analysis using directional Gabor wavelets for accurate detection of the rain events. An optoelectronic joint transform correlator is proposed to provide ultra fast processing and wavelet analysis. Computer simulations of the proposed

  5. 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.

  6. Polarimetric rainfall retrieval from a C-Band weather radar in a tropical environment (The Philippines)

    NASA Astrophysics Data System (ADS)

    Crisologo, I.; Vulpiani, G.; Abon, C. C.; David, C. P. C.; Bronstert, A.; Heistermann, Maik

    2014-11-01

    We evaluated the potential of polarimetric rainfall retrieval methods for the Tagaytay C-Band weather radar in the Philippines. For this purpose, we combined a method for fuzzy echo classification, an approach to extract and reconstruct the differential propagation phase, ? DP , and a polarimetric self-consistency approach to calibrate horizontal and differential reflectivity. The reconstructed ? DP was used to estimate path-integrated attenuation and to retrieve the specific differential phase, K DP . All related algorithms were transparently implemented in the Open Source radar processing software wradlib. Rainfall was then estimated from different variables: from re-calibrated reflectivity, from re-calibrated reflectivity that has been corrected for path-integrated attenuation, from the specific differential phase, and from a combination of reflectivity and specific differential phase. As an additional benchmark, rainfall was estimated by interpolating the rainfall observed by rain gauges. We evaluated the rainfall products for daily and hourly accumulations. For this purpose, we used observations of 16 rain gauges from a five-month period in the 2012 wet season. It turned out that the retrieval of rainfall from K DP substantially improved the rainfall estimation at both daily and hourly time scales. The measurement of reflectivity apparently was impaired by severe miscalibration while K DP was immune to such effects. Daily accumulations of rainfall retrieved from K DP showed a very low estimation bias and small random errors. Random scatter was, though, strongly present in hourly accumulations.

  7. ESTIMATING RAINFALL INTENSITIES FROM WEATHER RADAR DATA: THE SCALE DEPENDENCY PROBLEM 1490

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Meteorological radar is a remote sensing system that provides rainfall estimations at high spatial and temporal resolution. The radar-based rainfall intensities (R) are calculated from the observed radar reflectivities (Z). In this paper we explore scale-dependency of the power-law Z-R parameters w...

  8. Evaluation of radar and automatic weather station data assimilation for a heavy rainfall event in southern China

    NASA Astrophysics Data System (ADS)

    Hou, Tuanjie; Kong, Fanyou; Chen, Xunlai; Lei, Hengchi; Hu, Zhaoxia

    2015-07-01

    To improve the accuracy of short-term (0-12 h) forecasts of severe weather in southern China, a real-time storm-scale forecasting system, the Hourly Assimilation and Prediction System (HAPS), has been implemented in Shenzhen, China. The forecasting system is characterized by combining the Advanced Research Weather Research and Forecasting (WRF-ARW) model and the Advanced Regional Prediction System (ARPS) three-dimensional variational data assimilation (3DVAR) package. It is capable of assimilating radar reflectivity and radial velocity data from multiple Doppler radars as well as surface automatic weather station (AWS) data. Experiments are designed to evaluate the impacts of data assimilation on quantitative precipitation forecasting (QPF) by studying a heavy rainfall event in southern China. The forecasts from these experiments are verified against radar, surface, and precipitation observations. Comparison of echo structure and accumulated precipitation suggests that radar data assimilation is useful in improving the short-term forecast by capturing the location and orientation of the band of accumulated rainfall. The assimilation of radar data improves the short-term precipitation forecast skill by up to 9 hours by producing more convection. The slight but generally positive impact that surface AWS data has on the forecast of near-surface variables can last up to 6-9 hours. The assimilation of AWS observations alone has some benefit for improving the Fractions Skill Score (FSS) and bias scores; when radar data are assimilated, the additional AWS data may increase the degree of rainfall overprediction.

  9. Improved estimation of heavy rainfall by weather radar after reflectivity correction and accounting for raindrop size distribution variability

    NASA Astrophysics Data System (ADS)

    Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

    2015-04-01

    Between 25 and 27 August 2010 a long-duration mesoscale convective system was observed above the Netherlands, locally giving rise to rainfall accumulations exceeding 150 mm. Correctly measuring the amount of precipitation during such an extreme event is important, both from a hydrological and meteorological perspective. Unfortunately, the operational weather radar measurements were affected by multiple sources of error and only 30% of the precipitation observed by rain gauges was estimated. Such an underestimation of heavy rainfall, albeit generally less strong than in this extreme case, is typical for operational weather radar in The Netherlands. In general weather radar measurement errors can be subdivided into two groups: (1) errors affecting the volumetric reflectivity measurements (e.g. ground clutter, radar calibration, vertical profile of reflectivity) and (2) errors resulting from variations in the raindrop size distribution that in turn result in incorrect rainfall intensity and attenuation estimates from observed reflectivity measurements. A stepwise procedure to correct for the first group of errors leads to large improvements in the quality of the estimated precipitation, increasing the radar rainfall accumulations to about 65% of those observed by gauges. To correct for the second group of errors, a coherent method is presented linking the parameters of the radar reflectivity-rain rate (Z-R) and radar reflectivity-specific attenuation (Z-k) relationships to the normalized drop size distribution (DSD). Two different procedures were applied. First, normalized DSD parameters for the whole event and for each precipitation type separately (convective, stratiform and undefined) were obtained using local disdrometer observations. Second, 10,000 randomly generated plausible normalized drop size distributions were used for rainfall estimation, to evaluate whether this Monte Carlo method would improve the quality of weather radar rainfall products. Using the disdrometer information, the best results were obtained in case no differentiation between precipitation type (convective, stratiform and undefined) was made, increasing the event accumulations to more than 80% of those observed by gauges. For the randomly optimized procedure, radar precipitation estimates further improve and closely resemble observations in case one differentiates between precipitation type. However, the optimal parameter sets are very different from those derived from disdrometer observations. It is therefore questionable if single disdrometer observations are suitable for large-scale quantitative precipitation estimation, especially if the disdrometer is located relatively far away from the main rain event, which was the case in this study. In conclusion, this study shows the benefit of applying detailed error correction methods to improve the quality of the weather radar product, but also confirms the need to be cautious using locally obtained disdrometer measurements.

  10. Quasi-real time estimation of intense rainfall rates from weather radar

    NASA Astrophysics Data System (ADS)

    Libertino, Andrea; Allamano, Paola; Claps, Pierluigi; Cremonini, Roberto; Laio, Francesco

    2015-04-01

    Rainfall intensity estimation from radar is known to be prone to different sources of uncertainty, both in the detection and in the processing phase. These sources of uncertainty are especially relevant when severe rainfall rates are considered, thus calling for the adoption of advanced methods for the estimation of the rainfall rate from radar observations. We introduce a quasi-real time procedure for the adaptive estimation of the coefficients of the Z-R relation that links radar reflectivity to rainfall rate. The proposed quasi-real time calibration can grant Z-R relationships consistent with the evolution of the event while the use of a spatially adaptive approach makes the technique amenable to be applied in large areas with complex orography. The aim is to define a simple and operative methodology suitable for a systematic and possibly unsupervised application, capable to reconstruct the whole spectrum of intensities occurred during an intense rainfall event. We propose to readjust the power-law equation commonly used to transform reflectivity to rainfall intensity at each time step, calibrating its parameters by means of Z-R pairs collected in the time proximity of the considered instant. Z-R data are filtered with a reflectivity threshold, which varies in time, in order to discriminate between the presence and absence of rainfall. For every location, the spatial calibration domain is limited to the rain gauges belonging to a neighbourhood. Z-R coefficients are estimated for each location and each time step by minimizing the standard deviation between observed and estimated rainfall, through a non-linear procedure. The case study includes a set of 16 severe rainfall events occurred in the north-west of Italy. The technique outperforms the classical estimation methods for most of the analysed events and shows significant potential for operational uses. The determination coefficient undergoes up to 30% improvements and the BIAS values are reduced, for stratiform events, up to 80% of the values obtained with the classical non-adaptive Z-R relations.

  11. Spaceborne weather radar

    Microsoft Academic Search

    Robert Meneghini; Toshiaki Kozu

    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

  12. Snowfall and rainfall forecasting from the images of weather radar with artificial neural networks

    Microsoft Academic Search

    K. Ochiai; H. Suzuki; S. Suzuki; N. Sonehara; Y. Tokunaga

    1996-01-01

    We discuss problems of the weather forecasting technique with artificial neural networks and describe some solutions. We show that the computational time for learning with an acceleration learning algorithm can be reduced about 10 percent. To overcome the problem of overtraining, the pruning method is introduced and the prediction error is decreased about 20 percent. Using the data obtained over

  13. 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.

  14. Weather Radar Network Design

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2008-01-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively amounting to a greater ability to measure

  15. Weather and radar interactions

    Microsoft Academic Search

    J. P. Booth

    2005-01-01

    This paper discusses the effects of weather on radar system performance. This discussion were based on computer simulations and climatological data. The relationships between frequency and range were explored as they interact with the weather. This effort is being conducted in the RF Technology Division of the Applied Sensors, Guidance, and Electronics Directorate, US Army Aviation and Missile Research, Development,

  16. Terminal Doppler weather radar

    Microsoft Academic Search

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

    1990-01-01

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

  17. New weather radar coming

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    What would you call the next generation of radar for severe weather prediction? NEXRAD, of course. A prototype for the new system was recently completed in Norman, Okla., and by the early 1990s up to 195 stations around the United States will be tracking dangerous weather and sending faster, more accurate, and more detailed warnings to the public.NEXRAD is being built for the Departments of Commerce, Transportation, and Defense by the Unisys Corporation under a $450 million contract signed in December 1987. Th e system will be used by the National Weather Service, the Federal Aviation Administration (FAA), and the U.S. Air Force and Navy. The NEXRAD radar tower in Norman is expected to be operational in October.

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

    Microsoft Academic Search

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

    1998-01-01

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

  19. Weather Radar and Instrumentation: Laboratory Modules

    NSDL National Science Digital Library

    These 16 radar education modules, developed for the Weather Radar and Instrumentation Curriculum at the University of Oklahoma, provide hands-on instruction for beginning, intermediate, or advanced students to learn about radar systems, especially weather radar. Topics include hardware, weather radar, adaptive systems, advanced hydrometeors, applications of weather radar, and atmospheric interpretations. The modules may be downloaded.

  20. INTEGRATED CONTROL OF COMBINED SEWER REGULATORS USING WEATHER RADAR

    EPA Science Inventory

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

  1. Classification algorithms for weather radar

    Microsoft Academic Search

    Felix Yanovsky; Vitaly Marchuk; Yaroslav Ostrovsky; Yulia Averyanova

    2008-01-01

    Theory, measurements, and signal processing applying to the radar remote sensing of weather objects are considered. Algorithms for hydrometeor type and turbulence intensity recognition are developed and analyzed. Particularly, fuzzy logic and neural network approaches are applied for weather radar signal processing.

  2. Analysis of weather radar return

    Microsoft Academic Search

    D. Payne

    1977-01-01

    A mathematical model of detected clutter from an airborne weather radar of conventional design is developed. The model is the joint probability density of samples of radar return from hydrometeors at the same nominal range and scan angle. It is developed from analysis of the effect on the received signal of the following parameters: inhomogeneous hydrometeor motion, radar frequency stability,

  3. Correction of Polarimetric Radar Reflectivity Measurements and2 Rainfall Estimates for Apparent Vertical Profile in Stratiform Rain3

    E-print Network

    Marzano, Frank Silvio

    and rainfall2 estimates (VPR) in plan-position indicator (PPI) scans of polarimetric weather radars, rainfall20 21 22 #12;3 1. Introduction1 2 The deployment of weather radars in mountainous terrain at low elevation angles of the radar4 antenna. For quantitative precipitation estimation in complex

  4. A 10-year radar-based climatology of rainfall Aart Overeem, Iwan Holleman, Adri Buishand

    E-print Network

    Stoffelen, Ad

    A 10-year radar-based climatology of rainfall Aart Overeem, Iwan Holleman, Adri Buishand Royal@knmi.nl I. INTRODUCTION Weather radars give quantitative precipitation estimates (QPE) over large areas radar data sets become available (e.g. Allen and DeGaetano, 2005; Germann et al., 2006), radar data

  5. ERAD 2012 -THE SEVENTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGY Investigating the influence of rainfall spatial

    E-print Network

    Paris-Sud XI, Université de

    the influence of rainfall spatial variability on flow simulation Florent Lobligeois 1 , Vazken Andréassian 1 Weather radar is considered to be helpful for hydrological forecasting since it provides rainfall errors inherent to the radar rainfall estimates greatly affect rainfall-runoff simulations. As a result

  6. Merging WSR-88D stage III radar rainfall data with rain gauge measurements using wavelet analysis

    Microsoft Academic Search

    Oscar Anthony Kalinga; Thian Yew Gan

    2012-01-01

    Albeit weather surveillance radar (WSR)-88D stage III radar rainfall (RR) data can generally capture the spatial variability of precipitation fields, its rainfall depth for cold seasons dominated by stratiform storms tends to be underestimated. This study proposed merging WSR-88D stage III data with rain gauge data using the Haar wavelet scheme and compared its with that merged by the statistical

  7. Merging WSR-88D stage III radar rainfall data with rain gauge measurements using wavelet analysis

    Microsoft Academic Search

    Oscar Anthony Kalinga; Thian Yew Gan

    2011-01-01

    Albeit weather surveillance radar (WSR)-88D stage III radar rainfall (RR) data can generally capture the spatial variability of precipitation fields, its rainfall depth for cold seasons dominated by stratiform storms tends to be underestimated. This study proposed merging WSR-88D stage III data with rain gauge data using the Haar wavelet scheme and compared its with that merged by the statistical

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  9. 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...

  10. Australian Weather Watch Radar Home Page

    NSDL National Science Digital Library

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

  11. 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.

  12. 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.

  13. 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 variogram) of the triggering rainfall. These results show that weather radar has the potential to effectively increase the accuracy of rainfall thresholds for debris flow occurrence. However, these benefits may only be achieved if the same monitoring instrumentation is used both to derive the rainfall thresholds and for use of thresholds for real-time identification of debris flows occurrence. References Nikolopoulos, E.I., Borga M., Crema S., Marchi L, Marra F. & Guzzetti F., 2014. Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris-flow occurrence. Geomorphology (conditionally accepted) Peruccacci, S., Brunetti, M.T., Luciani, S., Vennari, C., and Guzzetti, F., 2012. Lithological and seasonal control of rainfall thresholds for the possible initiation of landslides in central Italy, Geomorphology, 139-140, 79-90, 2012.

  14. Laser radar in adverse weather

    NASA Astrophysics Data System (ADS)

    Grantham, Jeffrey W.; Stargardt, C. D.; Dungey, Clifton; Meidunas, Eduardo C.

    1997-08-01

    Laser radar image of an outdoor target scene were collected in adverse weather such as rain and fog during the course of one year. Included in this collection is imagery in fogs with visibilities less than 0.2 km and rains with rain rates of up to 180 mm/hr. The targets were small buildings, target panels and a mobile target, all approximately 500 m in distance from the laser radar system. The laser radar system used was a direct-detection 1.06 micrometers system designed to operate at 1 km in clear weather. Using these collected images, dropout pixels and false returns were correlated with rain rate and visibility. Dropouts and false returns were found to follow a linear relationship with rain rate and an exponential decreasing relationship with visibility. Empirical equations were developed from least square fits of the data to predict the dropouts and false returns, given the rain rate and visibility. Finally, fog and rain data from 450 images was combined and correlated into visibility intervals so that one can predict the dropout and false return percentages given a visibility in either fig or rain.

  15. Singularity-sensitive merging of radar and raingauge rainfall data

    NASA Astrophysics Data System (ADS)

    Wang, Li-Pen; Willems, Patrick; Ochoa-Rodriguez, Susana; Onof, Christian

    2014-05-01

    Traditionally, urban hydrological applications relied mainly upon rain gauge data as input as these provide accurate point rainfall estimates near the ground surface. However, they cannot capture the spatial variability of rainfall, which has a significant impact on the urban hydrological system and thus on the modelling of urban pluvial flooding. Thanks to the development of radar technology, weather radar has been playing an increasingly important role in urban hydrology. Radars can survey large areas and better capture the spatial variability of the rainfall, thus improving the short term predictability of rainfall and flooding. However, the accuracy of radar measurements is in general insufficient, particularly in the case of extreme rainfall magnitudes. This has a tremendous effect on the subsequent hydraulic model outputs. In order to improve the accuracy of radar rainfall estimates while preserving their spatial description of rainfall fields, it is possible to dynamically adjust them based on rain gauge measurements. Studies on this subject have been carried out over the last few years, though most of them focus on the hydrological applications at large scales. A couple of recent research works have examined the applicability of these adjustment techniques to urban-scale hydrological applications and concluded that these techniques can effectively reduce rainfall bias, thus leading to improvements in the reproduction of hydraulic outputs (Wang et al., 2013). However, underestimation of storm peaks can still be seen after adjustment and this is particularly significant in the case of small drainage areas and for extreme rainfall magnitudes. This may be due to the fact that the underlying adjustment techniques, mainly based upon Gaussian approximations, cannot properly cope with the non-normality observed in urban scale applications. With the purpose of improving this aspect, a methodology has been developed which identifies the local extremes or 'singularities' of radar rainfall fields and preserves them throughout the merging process (Wang and Onof, 2013). Singularities are defined through the fact that the areal average rainfall increases as a power function when the area decreases (Cheng et al., 1994). In the proposed methodology singularities are first identified and extracted from the radar rainfall field. The resulting non-singular radar field is then used in the merging process and the singularities are subsequently and proportionally added back to the final reconstructed rainfall field. A full-scale testing of this methodology in an urban area in the UK has been conducted and the result suggests that the original Bayesian data merging technique (Todini, 2001) could be effectively improved by incorporating this singularity analysis. References Cheng, Q., et al., (1994) Journal of Geochemical Exploration, 51(2), 109-130. Todini, E., (2001) Hydrology and Earth System Sciences, 5, 187-199. Wang, L. et al., (2013) Water Science & Technology, 68(4), 737-747. Wang, L. and Onof, C., (2013) Hydrofractals '13, Kos island, Greece.

  16. Analyses of the temporal and spatial structures of heavy rainfall from a catalog of high-resolution radar rainfall fields

    NASA Astrophysics Data System (ADS)

    Thorndahl, Søren; Smith, James A.; Baeck, Mary Lynn; Krajewski, Witold F.

    2014-07-01

    In this paper, we develop a storm catalog of heavy rainfall events for a region centered on the Milwaukee, Wisconsin WSR-88D (Weather Surveillance Radar - 1988 Doppler) radar. The study region includes portions of southern Wisconsin, northern Illinois and Lake Michigan. The long-term objective of this study is to develop rainfall frequency analysis methods based on a storm catalog of major rain events. The specific objectives of this study are to develop a long-term catalog of high-resolution radar rainfall fields and characterize key features of the space-time variability of rainfall. The research questions that underlie these objectives are: 1) What are the spatial heterogeneities of rainfall over the study region for major flood-producing storm systems? 2) What are the key elements of storm evolution that control the scale-dependent properties of extreme rainfall? The storm catalog contains a record of the 50 “largest” storm days during the 1996-2011 observation period. We show that mean rainfall for the 50 largest storm days exhibits pronounced spatial heterogeneity with a broad maximum in western Wisconsin and a minimum in the eastern portion of the study region over Lake Michigan. We also show that there is a narrow line of maximum mean rainfall extending from west to east along the Wisconsin-Illinois border. This feature is tied to a maximum in the probability of daily rainfall exceeding 100 mm. There are characteristic elements to the storm life cycle of heavy rainfall days that relate to size, structure and evolution of heavy rainfall. Extreme rainfall is also linked with severe weather (tornados, large hail and damaging wind). The diurnal cycle of rainfall for heavy rain days is characterized by an early peak in the largest rainfall rates, an afternoon-evening peak in rain area exceeding 25 mm h- 1 and development of a large stratiform rain area during the night and early morning.

  17. A GIS methodology for the analysis of weather radar precipitation data

    Microsoft Academic Search

    M. A. Gad; I. K. Tsanis

    2003-01-01

    A GIS multi-component module was developed within the ArcView GIS environment for processing and analysing weather radar precipitation data. The module is capable of: (a) reading geo-reference radar data and comparing it with rain-gauge network data, (b) estimating the kinematics of rainfall patterns, such as the storm speed and direction, and (c) accumulating radar-derived rainfall depths. By bringing the spatial

  18. Integration of weather radar data into a raster GIS framework for improved flood estimation

    Microsoft Academic Search

    B. Yu; A. Seed; L. Pu; T. Malone

    2005-01-01

    Weather radar data were used to estimate rainfall fields at 2-km resolution for a large flood event in 1999 in south-east Queensland, Australia, and subsequently integrated with a raster-based hydrologic model (RAMS) for runoff generation and flow routing. Gauge-based and radar-based temporal storm patterns are quite similar for the storm event. Agreement between gauge-based and radar-based event rainfall totals is

  19. Weather Radar signals with Alpha Stable Distributions

    Microsoft Academic Search

    M LAGHA

    This work, treats about a modeling of the weather precipitation echoes detected by a weather pulse Doppler radar. The methods used for the simulation of the Doppler spectrum, and I & Q signals representing the precipitations radar echoes, is based on a macroscopic models, i.e. random processes with assigned spectra. We propose global model, with a power spectrum having a

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

    Microsoft Academic Search

    Miguel Angel Rico-Ramirez; Ian David Cluckie

    2008-01-01

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

  1. Differences in radar derived rainfall amounts due to sampling intervals 

    E-print Network

    Zdenek, David James

    1986-01-01

    Table 1 Characteristics of the Texas ASM 10 cm radar 2 Basic description of rainfall events . 3 Constants and relationships. 4 R-squared values for the different sampling schemes. Page 35 LIST OF FIGURES Figure Rainfall amounts recorded on day... recorded on day 169, 1985 Rainfall amounts recorded on day 331, 1985 Radar derived rainfall differences due to systematic sampl- ing, 5 km by 5 km grid areas . . Radar derived rainfall differences due to random sampling, 5 km by 5 km grid areas. Radar...

  2. Modeling Radar Rainfall Estimation Uncertainties: Random Error Model

    E-print Network

    AghaKouchak, Amir

    Modeling Radar Rainfall Estimation Uncertainties: Random Error Model A. AghaKouchak1 ; E. Habib2 ; and A. Bárdossy3 Abstract: Precipitation is a major input in hydrological models. Radar rainfall data obtained form reflectivity patterns are subject to various errors such as errors in reflectivity-rainfall Z

  3. Robust Sparse Sensing Using Weather Radar

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The ability of a weather radar to detect weak echoes is limited by the presence of noise or unwanted echoes. Some of these unwanted signals originate externally to the radar system, such as cosmic noise, radome reflections, interference from co-located radars, and power transmission lines. The internal source of noise in microwave radar receiver is mainly thermal. The thermal noise from various microwave devices in the radar receiver tends to lower the signal-to-noise ratio, thereby masking the weaker signals. Recently, the compressed sensing (CS) technique has emerged as a novel signal sampling paradigm that allows perfect reconstruction of signals sampled at frequencies lower than the Nyquist rate. Many radar and remote sensing applications require efficient and rapid data acquisition. The application of CS to weather radars may allow for faster target update rates without compromising the accuracy of target information. In our previous work, we demonstrated recovery of an entire precipitation scene from its compressed-sensed version by using the matrix completion approach. In this study, we characterize the performance of such a CS-based weather radar in the presence of additive noise. We use a signal model where the precipitation signals form a low-rank matrix that is corrupted with (bounded) noise. Using recent advances in algorithms for matrix completion from few noisy observations, we reconstruct the precipitation scene with reasonable accuracy. We test and demonstrate our approach using the data collected by Iowa X-band Polarimetric (XPOL) weather radars.

  4. Application of GIS for processing and establishing the correlation between weather radar reflectivity and precipitation data

    Microsoft Academic Search

    Y. Gorokhovich; G. Villarini

    2005-01-01

    Correlation between weather radar reflectivity and precipitation data collected by rain gauges allows empirical formulae to be obtained that can be used to create continuous rainfall surfaces from discrete data. Such surfaces are useful in distributed hydrologic modelling and early warning systems in flood management. Because of the spatial relationship between rain gauge locations and radar coverage area, GIS provides

  5. Censoring Biological Echoes in Weather Radar Images

    Microsoft Academic Search

    Valliappa Lakshmanan; Jian Zhang

    2009-01-01

    Weather radar data is susceptible to several artifacts due to anamalous propagation, ground clutter, electronic interference, sun angle, second-trip echoes and biological contaminants such as insects, bats and birds. Several meth- ods of censoring radar reflectivity data have been devised and described in the literature. However, they all rely on analyzing the local texture and vertical profile of reflectivity fields.

  6. Spaceborne Radar Measurements of Rainfall Vertical Velocity

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Tanelli, Simone; Giuli, Dino; Durden, Stephen L.; Facheris, Luca

    2000-01-01

    This paper studies the performance of a spaceborne precipitation radar in measuring vertical Doppler velocity of rainfall. As far as a downward pointing precipitation radar is concerned, one of the major problems affecting Doppler measurement at the nadir direction arises from the Non-Uniform Beam-Filling effect (NUBF). That is, when significant variation in rain rate is present within the radar IFOV (Instrument Field of View) in the along track direction. the Doppler shift caused by the radial component of the horizontal speed of the satellite is weighted differently among the portions of IFOV. The effects of this non-uniform weighting may dominate any other contribution. Under this condition, shape, average value and width of the Doppler spectrum may not be directly correlated with the vertical velocity of the precipitating particles. However, by using an inversion technique which over-samples the radar measurements in the along track direction, we show that the shift due to NUBF can be evaluated, and that the NUBF induced errors on average fall speed can be reduced.

  7. Extreme compression of weather radar data

    Microsoft Academic Search

    Vishnu V. Makkapati; Pravas R. Mahapatra

    2007-01-01

    A method for achieving extreme levels of compression of high-volumeweather radar data is presented. Weather reflectivity contours, as per National Weather Service or custom thresholds, are processed by tracing their departure from a smoothed version to obtain the local extrema which serve as control points. The control points, which are transmitted inrelative coordinates for further compression, are interpolated using asecond-degree

  8. Course Syllabus Weather Radar Theory and Practice

    E-print Network

    Droegemeier, Kelvin K.

    Motivation and Historical Perspective of Weather Radar Chapter 2 Electromagnetic Waves and Propagation and P. Hobbs, 2006 Fundamentals of Signals and Systems, 2nd Ed, E. W. Kamen and B. S. Heck, 2000 Probability, Random Variables, and Stochastic Processes, 3rd Ed, A. Papoulis, 1991 Fundamental of Applied

  9. Radar rainfall accumulation estimation and nowcasting for real time flood warning

    NASA Astrophysics Data System (ADS)

    Burton, A.; Hannesen, R.; O`Connell, P. E.

    2003-04-01

    The EC project MUSIC (EVK1-CT-2000-00058) aims to develop a flood warning system to support operational decisions for the reduction of flood risk. An important component will be a rainfall nowcasting facility, whereby the location and intensity of rainfall is forecast for up to 6 hours ahead with a spatial resolution of about 2km. The characteristics of rainfall forecasts estimated using Numerical Weather Prediction are such that a direct forecast based on rainfall observations using a simple model can achieve a higher skill score for a short period, of the order of 4 hours. This is the aim of the MUSIC rainfall nowcasting system. Existing methodologies quantify the present precipitation state in terms of statistical properties or feature identification. They then achieve the forecasting step by extrapolating state variables (often using auto regressive models or artificial neural networks) and have sometimes used additional data from satellite observations or numerical weather prediction. Similarly, the method applied here is to decompose a radar image into features which are then tracked from one image to the next using an object-orientated methodology. The tracking uses lag-correlation to estimate velocity with a highly efficient algorithm. A number of alternative formulations of the forecasting step will be described. The interface between rainfall estimation and rainfall-runoff modelling will also be considered. Rainfall-runoff models typically use rainfall data which is accumulated in time. When intense precipitation features move with a high velocity in the time interval between radar scans, care must be taken to ensure that accumulation estimates are free from errors caused by the discrete nature of radar scans. The accumulation component within the MUSIC system addresses this issue.

  10. Radar subpixel-scale rainfall variability and uncertainty: a lesson learned from observations of a dense rain-gauge network

    NASA Astrophysics Data System (ADS)

    Peleg, N.; Ben-Asher, M.; Morin, E.

    2013-01-01

    Hydrological models for runoff estimations and flash-flood predictions are very sensitive to rainfall's spatial and temporal variability. The increasing use of radar and satellite data in hydrological applications, due to the sparse distribution of rain gauges over most catchments worldwide, requires improving our knowledge of the uncertainties of these data. In 2011, a new super-dense network of rain gauges, containing 27 gauges covering an area of about 4 km2, was installed near Kibbutz Galed in northern Israel. This network was established for a detailed exploration of the uncertainties and errors regarding rainfall variability in remote-sensing at subpixel-scale resolution. In this paper, we present the analysis of the first year's record collected from this network and from the Shacham weather radar. The gauge-rainfall spatial correlation and uncertainty were examined along with the estimated radar error. The zero-distance correlation between rain gauges was high (0.92 on the 1-min scale) and increased as the time scale increased. The variance of the differences between radar pixel rainfall and averaged point rainfall (the variance reduction factor - VRF) was 1.6%, as measured for the 1-min scale. It was also found that at least four uniformly distributed rain stations are needed to represent the rainfall on the radar pixel scale. The radar-rain gauge error was mainly derived from radar estimation errors as the gauge sampling error contributed up to 22% to the total error. The radar rainfall estimations improved with increasing time scale and the radar-to-true rainfall ratio decreased with increasing time scale. Rainfall measurements collected with this network of rain gauges in the coming years will be used for further examination of rainfall's spatial and temporal variability.

  11. Influences of temporal rainfall radar and spatial rainfall-runoff model resolution on flood prediction

    NASA Astrophysics Data System (ADS)

    Weiler, Markus; Steinbrich, Andreas

    2013-04-01

    The rainfall-runoff-model DROGen (Distributed RunOff Generation) was developed to simulate runoff generation processes during floods and flash floods generation with a very high spatial resolution for the whole state of Baden-Württemberg in Southwest Germany. The model connects available spatial geo information with detailed process understanding at the plot and hillslope scale and is not calibrated. The model was successfully validated in 8 meso-scale watersheds with different geology, soils, topography and land-use and the results were very satisfying. We believe that the high spatial resolution of 1*1m² and a temporal resolution of 1 hour especially improved flow dynamics and the runoff concentration behaviour of the different runoff components. Some spatial information used by DROGen is available in very high resolution of 1*1m² (e.g. DEM and degree of sealing of land surface). Other data are much more generalized (e.g. soil information at the scale of 1:200.000) or at a fixed temporal resolution of one hour (e.g. calibrated precipitation radar data of the German weather survey (RADOLAN)). In order to find the adequate temporal and spatial resolution we investigated how the the spatial resolution of the geo data and the temporal resolution of the rainfall radar data effects the model result. Regarding the spatial resolution, we found, that the processes of runoff generation and runoff concentration are sensitive at different spatial scales. A decrease of spatial resolution from 1m to 25m lead to an implausible increase of the generation of saturation overland flow and to an accelerated concentration of subsurface flow, while Hortonian overland flow was almost not affected by the spatial resolution. For the model validation runs we realized that for short convective rain events a one hour resolution of the rainfall data might be not sufficient because of severe underestimation of peak intensities. We developed and tested a new method to estimate the temporal distribution of rain intensity in higher resolution by using only the information of the hourly radar data and an assumed temporal distribution of rainfall at each radar grid cell. The methods preserves the total rainfall amount at each cell and preserves the overall rainfall pattern and movement of precipitation cells. Generally, we could improve the prediction of the model for short convective events in particular for the peak discharge. The higher temporal resolution effects the runoff generation and depends strongly on soil characteristics. On soils with high infiltration capacity the increase of temporal resolution effects the generation of fast overland runoff. This effect decreases with decreasing infiltration capacity of soils. The analysis revealed that a variable temporal resolution is needed to model convective and advective rainfall events with the same model parameterization. A "correct" spatial resolution of the distributed model, however, depends strongly on the dominant runoff generation process in a watershed and is also different for runoff generation and runoff concentration.

  12. On the sensitivity of weather radars

    Microsoft Academic Search

    Paul L. Smith

    1986-01-01

    This paper discusses the subject of weather radar system sensitivity from a general point of view, with emphasis on the influence of wavelength. Expressions for the echo signal-to-noise ratio are examined using a detection theory approach to develop factors describing the effects of different signal processing techniques. Then the variation of the equivalent signal-to-noise ratio with wavelength under certain typical

  13. Multichannel conversion of the National Weather Radar Testbed receiver

    Microsoft Academic Search

    G. E. Crain; M. Yeary; Chad Kidder; A. Zahrai; G. Zhang; R. Doviak; R. Palmer; T.-Y. Yu; M. Xue; Y. Zhang; Q. Xu; P. Chilson

    2009-01-01

    The National Weather Radar Testbed (NWRT) system is based on WSR-88D technology enhanced with the significant capability of a phased array antenna. The agile beam capability provides a unique and powerful tool to focus weather radar asset on observation of severe weather phenomena including structures that lead to formation of these storms. The NWRT system has demonstrated the ability to

  14. Weather models as virtual sensors to data-driven rainfall predictions in urban watersheds

    NASA Astrophysics Data System (ADS)

    Cozzi, Lorenzo; Galelli, Stefano; Pascal, Samuel Jolivet De Marc; Castelletti, Andrea

    2013-04-01

    Weather and climate predictions are a key element of urban hydrology where they are used to inform water management and assist in flood warning delivering. Indeed, the modelling of the very fast dynamics of urbanized catchments can be substantially improved by the use of weather/rainfall predictions. For example, in Singapore Marina Reservoir catchment runoff processes have a very short time of concentration (roughly one hour) and observational data are thus nearly useless for runoff predictions and weather prediction are required. Unfortunately, radar nowcasting methods do not allow to carrying out long - term weather predictions, whereas numerical models are limited by their coarse spatial scale. Moreover, numerical models are usually poorly reliable because of the fast motion and limited spatial extension of rainfall events. In this study we investigate the combined use of data-driven modelling techniques and weather variables observed/simulated with a numerical model as a way to improve rainfall prediction accuracy and lead time in the Singapore metropolitan area. To explore the feasibility of the approach, we use a Weather Research and Forecast (WRF) model as a virtual sensor network for the input variables (the states of the WRF model) to a machine learning rainfall prediction model. More precisely, we combine an input variable selection method and a non-parametric tree-based model to characterize the empirical relation between the rainfall measured at the catchment level and all possible weather input variables provided by WRF model. We explore different lead time to evaluate the model reliability for different long - term predictions, as well as different time lags to see how past information could improve results. Results show that the proposed approach allow a significant improvement of the prediction accuracy of the WRF model on the Singapore urban area.

  15. Radar-based rainfall estimation: Improving Z/R relations through comparison of drop size distributions, rainfall rates and radar reflectivity patterns

    NASA Astrophysics Data System (ADS)

    Neuper, Malte; Ehret, Uwe

    2014-05-01

    The relation between the measured radar reflectivity factor Z and surface rainfall intensity R - the Z/R relation - is profoundly complex, so that in general one speaks about radar-based quantitative precipitation estimation (QPE) rather than exact measurement. Like in Plato's Allegory of the Cave, what we observe in the end is only the 'shadow' of the true rainfall field through a very small backscatter of an electromagnetic signal emitted by the radar, which we hope has been actually reflected by hydrometeors. The meteorological relevant and valuable Information is gained only indirectly by more or less justified assumptions. One of these assumptions concerns the drop size distribution, through which the rain intensity is finally associated with the measured radar reflectivity factor Z. The real drop size distribution is however subject to large spatial and temporal variability, and consequently so is the true Z/R relation. Better knowledge of the true spatio-temporal Z/R structure therefore has the potential to improve radar-based QPE compared to the common practice of applying a single or a few standard Z/R relations. To this end, we use observations from six laser-optic disdrometers, two vertically pointing micro rain radars, 205 rain gauges, one rawindsonde station and two C-band Doppler radars installed or operated in and near the Attert catchment (Luxembourg). The C-band radars and the rawindsonde station are operated by the Belgian and German Weather Services, the rain gauge data was partly provided by the French, Dutch, Belgian, German Weather Services and the Ministry of Agriculture of Luxembourg and the other equipment was installed as part of the interdisciplinary DFG research project CAOS (Catchment as Organized Systems). With the various data sets correlation analyzes were executed. In order to get a notion on the different appearance of the reflectivity patterns in the radar image, first of all various simple distribution indices (for example the Gini index, Rosenbluth index) were calculated and compared to the synoptic situation in general and the atmospheric stability in special. The indices were then related to the drop size distributions and the rain rate. Special emphasis was laid in an objective distinction between stratiform and convective precipitation and hereby altered droplet size distribution, respectively Z/R relationship. In our presentation we will show how convective and stratiform precipitation becomes manifest in the different distribution indices, which in turn are thought to represent different patterns in the radar image. We also present and discuss the correlation between these distribution indices and the evolution of the drop size distribution and the rain rate and compare a dynamically adopted Z/R relation to the standard Marshall-Palmer Z/R relation.

  16. SUB-PIXEL SCALE RAINFALL VARIABILITY AND THE EFFECTS ON SEPARATION OF RADAR AND GAUGE RAINFALL ERRORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As long recognized, one of the primary sources of the discrepancies in the 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 radar rainfall estimates and gauge measurements are...

  17. Radar Signatures for Severe Convective Weather

    NSDL National Science Digital Library

    2014-09-14

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

  18. 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, leading to a dynamic weighting scheme. The weighted combination method reduces the MSE by close to 50% compared to a traditional power law method for using the radar reflectivity. The combined method has the lowest overall error of the three methods over the densely gauged Sydney region.

  19. Weather radar to prevent air crashes

    NASA Astrophysics Data System (ADS)

    Bush, Susan M.

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

  20. USING METEOROLOGICAL RADAR TO LINK LANDSLIDES AND RAINFALL IN THE OREGON COAST RANGE

    E-print Network

    Roering, Joshua J.

    USING METEOROLOGICAL RADAR TO LINK LANDSLIDES AND RAINFALL IN THE OREGON COAST RANGE by AMANDA JANE #12;ii "Using Meteorological Radar to Link Landslides and Rainfall in the Oregon Coast Range METEOROLOGICAL RADAR TO LINK LANDSLIDES AND RAINFALL IN THE OREGON COAST RANGE Approved

  1. AN ALGORITHM FOR PREDICTING RADAR RAINFALL RATE Nazario D. Ramirez-Beltran

    E-print Network

    Gilbes, Fernando

    AN ALGORITHM FOR PREDICTING RADAR RAINFALL RATE Nazario D. Ramirez-Beltran 1 , Joan M. Castro2@me.ccny.cuny.edu An algorithm for predicting one to two hours in advance the spatial distribution of rainfall rate is introduced in this work. The suggested algorithm uses radar rainfall data to predict the rainfall field. The algorithm

  2. Local Area Weather Radar in Alpine Setting

    NASA Astrophysics Data System (ADS)

    Savina, M.

    2012-04-01

    Space-time variability of precipitation in orographically complex regions is a challenging research topic. The difficult accessibility of remote regions and the high elevations make difficult the operation of conventional raingauges and reduce the visibility of large scale radars. A solution to this limitation might be the use of a number of cost-effective short-range X-band radars as complement to raingauges and conventional, large and expensive weather radars. This paper presents the results of a pilot experiment, which aimed at i) developing and assessing the performance of a cost-effective X-band Local Area Weather Radar (LAWR) located in the orographically complex Alpine region and ii) testing whether it could lead to better understanding of the nature of the precipitation process, e.g. identifying any possible dependence between precipitation and topography. The LAWR was deployed between August 2007 and October 2011 on the summit of the Kl. Matterhorn, located in the Swiss Alps at 3883 m a.s.l. (Valais, Switzerland). This was the first time that a cost-effective X-band radar was installed at such elevation and could be tested in operation-like conditions. Beside the technological improvements that were necessary for a reliable functioning of the LAWR hardware, much effort went into the development of a set of radar corrections and into the design of a new Alpine Radar COnversion Model (ARCOM), which includes the algorithms necessary to convert radar received echoes into precipitation rates, specifically accounting for the presence of the pronounced topography. The ARCOM was developed and tested on the basis of a set of precipitation events for which precipitation was measured also by 43 automatic raingauges located within 60 km range from the radar antenna. Conversely to the state-of-the-art conversion models, ARCOM accounts not only for the seasonal climatological condition but also of geometric and orographic forcings such as partial beam filling and beam blocking. The results showed that the LAWR systems and the newly developed ARCOM can be successfully deployed in high mountain settings. Indeed the experimental LAWR was able to measure precipitation in all its forms as well as its spatial variability. The ARCOM proved to be stable and robust across seasons, precipitation types and intensities, and to be able to account for the disturbances due to orography. The LAWR observations were additionally used to study the distribution of precipitation occurrences in relation to elevation and topography. The results show in most of the observed events precipitation occurs in this sector of the Alps significantly more often in a given range of elevations, regardless of the season and of the event type. This suggests the limitation of the assumption of positive gradient of precipitation with elevation, which is frequently used in hydrological modelling applications, and points to the importance of measuring more accurately the space-time distribution of precipitation in orographically complex areas for a correct representation of the hydrologic response of mountain watersheds.

  3. Fuzzy Logic Tornado Detection Using High Resolution Weather Radar

    Microsoft Academic Search

    Timothy A. Alberts; Phillip B. Chilson; B. L. Cheong; R. D. Palmer

    2007-01-01

    In order to evaluate pulse compression for use in phased array weather radar systems, modifications to a weather radar simulator have been made, which incorporated phase- coding into its functionality. Data derived from Barker-coded pulses with matched and mismatched filters were evaluated against data obtained from uncoded pulses to determine the error performance. The output from the compressed data was

  4. Reconfigurable data acquisition system for weather radar applications

    Microsoft Academic Search

    Rishi Khasgiwale; Luko Krnan; Atchuthan Perinkulam; Russell Tessier

    2005-01-01

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

  5. Study on Rainfall Forecasting by Using Weather Satellite Imagery in a Small Watershed Located at Mountainous Area of Central Taiwan

    NASA Astrophysics Data System (ADS)

    Wei, C.; Cheng, K. S.

    Using meteorological radar and satellite imagery had become an efficient tool for rainfall forecasting However few studies were aimed to predict quantitative rainfall in small watersheds for flood forecasting by using remote sensing data Due to the terrain shelter and ground clutter effect of Central Mountain Ridges the application of meteorological radar data was limited in mountainous areas of central Taiwan This study devises a new scheme to predict rainfall of a small upstream watershed by combing GOES-9 geostationary weather satellite imagery and ground rainfall records which can be applied for local quantitative rainfall forecasting during periods of typhoon and heavy rainfall Imagery of two typhoon events in 2004 and five correspondent ground raingauges records of Chitou Forest Recreational Area which is located in upstream region of Bei-Shi river were analyzed in this study The watershed accounts for 12 7 square kilometers and altitudes ranging from 1000 m to 1800 m Basin-wide Average Rainfall BAR in study area were estimated by block kriging Cloud Top Temperature CTT from satellite imagery and ground hourly rainfall records were medium correlated The regression coefficient ranges from 0 5 to 0 7 and the value decreases as the altitude of the gauge site increases The regression coefficient of CCT and next 2 to 6 hour accumulated BAR decrease as the time scale increases The rainfall forecasting for BAR were analyzed by Kalman Filtering Technique The correlation coefficient and average hourly deviates between estimated and observed value of BAR for

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

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

  7. 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.

  8. 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 estimation of the CASA DFW QPE system, rainfall measurements from ground rain gauges will be used for evaluation purposes. This high-resolution QPE system is used for urban flash flood forecasting when coupled with hydrological models.

  9. Radar subpixel-scale rainfall variability and uncertainty: lessons learned from observations of a dense rain-gauge network

    NASA Astrophysics Data System (ADS)

    Peleg, N.; Ben-Asher, M.; Morin, E.

    2013-06-01

    Runoff and flash flood generation are very sensitive to rainfall's spatial and temporal variability. The increasing use of radar and satellite data in hydrological applications, due to the sparse distribution of rain gauges over most catchments worldwide, requires furthering our knowledge of the uncertainties of these data. In 2011, a new super-dense network of rain gauges containing 14 stations, each with two side-by-side gauges, was installed within a 4 km2 study area near Kibbutz Galed in northern Israel. This network was established for a detailed exploration of the uncertainties and errors regarding rainfall variability within a common pixel size of data obtained from remote sensing systems for timescales of 1 min to daily. In this paper, we present the analysis of the first year's record collected from this network and from the Shacham weather radar, located 63 km from the study area. The gauge-rainfall spatial correlation and uncertainty were examined along with the estimated radar error. The nugget parameter of the inter-gauge rainfall correlations was high (0.92 on the 1 min scale) and increased as the timescale increased. The variance reduction factor (VRF), representing the uncertainty from averaging a number of rain stations per pixel, ranged from 1.6% for the 1 min timescale to 0.07% for the daily scale. It was also found that at least three rain stations are needed to adequately represent the rainfall (VRF < 5%) on a typical radar pixel scale. The difference between radar and rain gauge rainfall was mainly attributed to radar estimation errors, while the gauge sampling error contributed up to 20% to the total difference. The ratio of radar rainfall to gauge-areal-averaged rainfall, expressed by the error distribution scatter parameter, decreased from 5.27 dB for 3 min timescale to 3.21 dB for the daily scale. The analysis of the radar errors and uncertainties suggest that a temporal scale of at least 10 min should be used for hydrological applications of the radar data. Rainfall measurements collected with this dense rain gauge network will be used for further examination of small-scale rainfall's spatial and temporal variability in the coming years.

  10. Sever Hazards Prediction Method by Using Phased Array Weather Radar (PAWR)

    NASA Astrophysics Data System (ADS)

    Michimoto, K.

    2014-12-01

    We are now research several sever hazards of meteorological phenomena, for example, thunderstorm, hail, heavy rain-fall, tornado, etc., by using Phased Array Weather Radar (PAWR). In this paper, we present our analyses between PAWRs echo data temporal variations and thunderstorms lightning activity, hail fall and/or heavy rain-fall rate, etc. We will develop nowcast and/or forecast methods of sever hazards and, in near future, we will prepare new prediction numerical model of sever hazards by using CReSS (Cloud Resolving Storm Simulator).

  11. 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.

  12. 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.

  13. 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-arid climatic transition.

  14. 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).

  15. Principles of weather radar network design at attenuating frequencies

    NASA Astrophysics Data System (ADS)

    Junyent, F.; Lim, S.; Chandrasekar, V.

    2009-09-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively, amounting to a greater ability to measure at lower beam heights, mitigating the effects of the Earth curvature, an increased spatial and temporal resolution in the measurements, the ability to perform multiple-radar measurements, and the capability of optimally and adaptively tasking the individual radars according to the meteorological scene. All of the previous points can be achieved while using less complex radar units than those in operational use today. All of the described potential benefits are governed by relationships between the characteristics of the individual radars composing the network and the network spatial distribution. Using the same network layout for two different classes of radars will create different coverage characteristics. Similarly, deploying one class of radars in two different network layouts will not yield the same coverage results. The relationship between the individual radar characteristics and the resulting network characteristics was presented in (Junyent and Chandrasekar, JAOT, 2009), and applied to both characterization and design of weather radar networks. In this paper, the previously developed radar network characterization analytical and numerical tools are extended to include radar signal attenuation statistics. Signal attenuation is becoming a greater concern as radar systems operating at higher frequencies such as C and X band are becoming commonplace. Attenuation effects when the radar signal is propagating through rain will influence parameters such as minimum detectable reflectivity and number of overlapping radars, which are also dependent both on single radar characteristics and network topology. Taking into account attenuation statistics collected at particular radar operating frequencies in the weather radar network design process, the attenuation margin for both the radar network and the individual radars composing the network can be obtained. Based on the attenuation margins, the number of overlapping of radars capable of sampling a given point in the network in the presence of a given spatial attenuation distribution can also be obtained.

  16. AN ALGORITHM FOR PROJECTING RADAR RAINFALL RATE Nazario D. Ramirez-Beltran1

    E-print Network

    Gilbes, Fernando

    AN ALGORITHM FOR PROJECTING RADAR RAINFALL RATE Nazario D. Ramirez-Beltran1 , Robert J. Kuligowski2) radar are used to project rainfall rate one or two hours in advance. The algorithm starts are extracted from the previous two radar images for each region. The forward selection algorithm is used

  17. Principles of weather radar network design at attenuating frequencies

    Microsoft Academic Search

    F. Junyent; S. Lim; V. Chandrasekar

    2009-01-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively, amounting to a greater ability to measure

  18. GIS-based weather radar siting procedure in mountainous terrain

    Microsoft Academic Search

    Christos Domenikiotis; Nicolaos R. Dalezios; Ioannis Faraslis

    2010-01-01

    This paper describes a weather radar siting procedure for a mountainous region in Greece using GIS. The established radar siting objectives consist of the detection and tracking of storms (rainstorms, hailstorms, and snowstorms) requiring operations at a low elevation angle as well as the detection of the vertical structure and evolution of a storm. Moreover, the objective includes precipitation intensity

  19. FREQUENCY DIVERSITY WIDEBAND WAVEORMS FOR DUAL-POLARIZATION WEATHER RADARS

    Microsoft Academic Search

    Nitin Bharadwaj; V. Chandrasekar

    Weather radar systems using solid-state transmitters are becoming increasingly viable. The transition from traditional high powered transmitters to solid-state transmitter is also useful to realize a network of low cost electronically steered X-band radars. However, solid-state transmitters have low peak powers which de- grades the sensitivity of the radar if used in a conven- tional way with narrow transmit pulse.

  20. A machine learning based approach to weather parameter estimation in Doppler weather radar

    Microsoft Academic Search

    Satoshi Kon; Toshihisa Tanaka; Humihiko Mizutani; Masakazu Wada

    2011-01-01

    An observed signal of the Doppler weather radar includes not only weather echoes but also a ground clutter. For accurate observation of weather data, we need to remove the effect of the ground clutter. In this paper, we propose to model the spectrum of an observed IQ signal as a mixture density function. To estimate the parameters of the density

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

    Microsoft Academic Search

    Jonggil Lee; Ernest G. Baxa

    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

  2. A WAY FORWARD WIND FARM - WEATHER RADAR COEXISTENCE

    Microsoft Academic Search

    Ron Guenther

    The Nation's weather services and the wind energy industry share common goals of enhancing the Nation's economy and quality of life for its citizens. Unfortunately, we have observed that sometimes the best locations for developing a wind energy project are near established weather radar sites, since both usually desire optimal siting on high, unobstructed terrain. In recent years, NEXRAD system

  3. 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.

  4. Optimizing weather radar observations using an adaptive multiquadric surface fitting algorithm

    NASA Astrophysics Data System (ADS)

    Martens, Brecht; Cabus, Pieter; De Jongh, Inge; Verhoest, Niko

    2013-04-01

    Real time forecasting of river flow is an essential tool in operational water management. Such real time modelling systems require well calibrated models which can make use of spatially distributed rainfall observations. Weather radars provide spatial data, however, since radar measurements are sensitive to a large range of error sources, often a discrepancy between radar observations and ground-based measurements, which are mostly considered as ground truth, can be observed. Through merging ground observations with the radar product, often referred to as data merging, one may force the radar observations to better correspond to the ground-based measurements, without losing the spatial information. In this paper, radar images and ground-based measurements of rainfall are merged based on interpolated gauge-adjustment factors (Moore et al., 1998; Cole and Moore, 2008) or scaling factors. Using the following equation, scaling factors (C(x?)) are calculated at each position x? where a gauge measurement (Ig(x?)) is available: Ig(x?)+-? C (x?) = Ir(x?)+ ? (1) where Ir(x?) is the radar-based observation in the pixel overlapping the rain gauge and ? is a constant making sure the scaling factor can be calculated when Ir(x?) is zero. These scaling factors are interpolated on the radar grid, resulting in a unique scaling factor for each pixel. Multiquadric surface fitting is used as an interpolation algorithm (Hardy, 1971): C*(x0) = aTv + a0 (2) where C*(x0) is the prediction at location x0, the vector a (Nx1, with N the number of ground-based measurements used) and the constant a0 parameters describing the surface and v an Nx1 vector containing the (Euclidian) distance between each point x? used in the interpolation and the point x0. The parameters describing the surface are derived by forcing the surface to be an exact interpolator and impose that the sum of the parameters in a should be zero. However, often, the surface is allowed to pass near the observations (i.e. the observed scaling factors C(x?)) on a distance a?K by introducing an offset parameter K, which results in slightly different equations to calculate a and a0. The described technique is currently being used by the Flemish Environmental Agency in an online forecasting system of river discharges within Flanders (Belgium). However, rescaling the radar data using the described algorithm is not always giving rise to an improved weather radar product. Probably one of the main reasons is the parameters K and ? which are implemented as constants. It can be expected that, among others, depending on the characteristics of the rainfall, different values for the parameters should be used. Adaptation of the parameter values is achieved by an online calibration of K and ? at each time step (every 15 minutes), using validated rain gauge measurements as ground truth. Results demonstrate that rescaling radar images using optimized values for K and ? at each time step lead to a significant improvement of the rainfall estimation, which in turn will result in higher quality discharge predictions. Moreover, it is shown that calibrated values for K and ? can be obtained in near-real time. References Cole, S. J., and Moore, R. J. (2008). Hydrological modelling using raingauge- and radar-based estimators of areal rainfall. Journal of Hydrology, 358(3-4), 159-181. Hardy, R.L., (1971) Multiquadric equations of topography and other irregular surfaces, Journal of Geophysical Research, 76(8): 1905-1915. Moore, R. J., Watson, B. C., Jones, D. A. and Black, K. B. (1989). London weather radar local calibration study. Technical report, Institute of Hydrology.

  5. Quantitative precipitation estimation for an X-band weather radar network

    NASA Astrophysics Data System (ADS)

    Chen, Haonan

    Currently, the Next Generation (NEXRAD) radar network, a joint effort of the U.S. Department of Commerce (DOC), Defense (DOD), and Transportation (DOT), provides radar data with updates every five-six minutes across the United States. This network consists of about 160 S-band (2.7 to 3.0 GHz) radar sites. At the maximum NEXRAD range of 230 km, the 0.5 degree radar beam is about 5.4 km above ground level (AGL) because of the effect of earth curvature. Consequently, much of the lower atmosphere (1-3 km AGL) cannot be observed by the NEXRAD. To overcome the fundamental coverage limitations of today's weather surveillance radars, and improve the spatial and temporal resolution issues, the National Science Foundation Engineering Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) was founded to revolutionize weather sensing in the lower atmosphere by deploying a dense network of shorter-range, low-power X-band dual-polarization radars. The distributed CASA radars are operating collaboratively to adapt the changing atmospheric conditions. Accomplishments and breakthroughs after five years operation have demonstrated the success of CASA program. Accurate radar quantitative precipitation estimation (QPE) has been pursued since the beginning of weather radar. For certain disaster prevention applications such as flash flood and landslide forecasting, the rain rate must however be measured at a high spatial and temporal resolution. To this end, high-resolution radar QPE is one of the major research activities conducted by the CASA community. A radar specific differential propagation phase (Kdp)-based QPE methodology has been developed in CASA. Unlike the rainfall estimation based on the power terms such as radar reflectivity (Z) and differential reflectivity (Zdr), Kdp-based QPE is less sensitive to the path attenuation, drop size distribution (DSD), and radar calibration errors. The CASA Kdp-based QPE system is also immune to the partial beam blockage and hail contamination. The performance of the CASA QPE system is validated and evaluated by using rain gauges. In CASA's Integrated Project 1 (IP1) test bed in Southwestern Oklahoma, a network of 20 rainfall gauges is used for cross-comparison. 40 rainfall cases, including severe, multicellular thunderstorms, squall lines and widespread stratiform rain, that happened during years 2007 - 2011, are used for validation and evaluation purpose. The performance scores illustrate that the CASA QPE system is a great improvement compared to the current state-of-the-art. In addition, the high-resolution CASA QPE products such as instantaneous rainfall rate map and hourly rainfall amount measurements can serve as a reliable input for various distributed hydrological models. The CASA QPE system can save lived and properties from hazardous flash floods by incorporating hydraulic and hydrologic models for flood monitoring and warning.

  6. Sampling-rate effects on radar-derived rainfall estimates 

    E-print Network

    Fornear, Jeffrey Lynn

    1985-01-01

    errors by the number of radar samples taken during the 80 min time span. 8 Plot of mean absolute error by sample interval for categories of mean rain rate (mm/h). 13 14 20 24 28 9 Plot of mean absolute error by sample interval for categories... of change of rain intensity with time, which he called sequen- tiall variability, written as IRl R2I + IR2-R I '. ~ + IR -R+ll N - 1 (2) where 0 is the sequential variability in mm/h, R is the mean rainfall rate in mm/h for the minute indicated...

  7. Simulation and Prediction of Weather Radar Clutter Using a Wave Propagator on High Resolution NWP Data

    Microsoft Academic Search

    Hans-Henrik Benzon; Thomas Bovith

    2008-01-01

    Weather radars are essential sensors for observation of precipitation in the troposphere and play a major part in weather forecasting and hydrological modelling. Clutter caused by non-standard wave propagation is a common problem in weather radar applications, and in this paper a method for prediction of this type of weather radar clutter is presented. The method uses a wave propagator

  8. Using raindrop size distributions from different types of disdrometer to establish weather radar algorithms

    NASA Astrophysics Data System (ADS)

    Baldini, Luca; Adirosi, Elisa; Roberto, Nicoletta; Vulpiani, Gianfranco; Russo, Fabio; Napolitano, Francesco

    2015-04-01

    Radar precipitation retrieval uses several relationships that parameterize precipitation properties (like rainfall rate and liquid water content and attenuation (in case of radars at attenuated frequencies such as those at C- and X- band) as a function of combinations of radar measurements. The uncertainty in such relations highly affects the uncertainty precipitation and attenuation estimates. A commonly used method to derive such relationships is to apply regression methods to precipitation measurements and radar observables simulated from datasets of drop size distributions (DSD) using microphysical and electromagnetic assumptions. DSD datasets are determined both by theoretical considerations (i.e. based on the assumption that the radar always samples raindrops whose sizes follow a gamma distribution) or from experimental measurements collected throughout the years by disdrometers. In principle, using long-term disdrometer measurements provide parameterizations more representative of a specific climatology. However, instrumental errors, specific of a disdrometer, can affect the results. In this study, different weather radar algorithms resulting from DSDs collected by diverse types of disdrometers, namely 2D video disdrometer, first and second generation of OTT Parsivel laser disdrometer, and Thies Clima laser disdrometer, in the area of Rome (Italy) are presented and discussed to establish at what extent dual-polarization radar algorithms derived from experimental DSD datasets are influenced by the different error structure of the different type of disdrometers used to collect the data.

  9. New Approaches to Rainfall and Flood Frequency Analysis Using High Resolution Radar Rainfall Fields and Stochastic Storm Transposition

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Conventional techniques for rainfall and flood frequency analysis in small watersheds involve a variety of assumptions regarding the spatial and temporal structure of extreme rainfall systems as well as how resulting runoff moves through the drainage network. These techniques were developed at a time when observational and computational resources were limited. They continue to be used in practice though their validity has not been fully examined. New observational and computational resources such as high-resolution radar rainfall estimates and distributed hydrologic models allow us to examine these assumptions and to develop alternative methods for estimating flood risk. We have developed a high-resolution (1 square km, 15-minute resolution) radar rainfall dataset for the 2001-2010 period using the Hydro-NEXRAD processing system, which has been bias corrected using a dense network of 71 rain gages in the Charlotte metropolitan area. The accuracy of the bias-corrected radar rainfall estimates compare favorably with rain gage measurements. The radar rainfall dataset is used in a stochastic storm transposition framework to estimate the frequency of extreme rainfall for urban watersheds ranging the point/radar pixel scale up to 240 square km, and can be combined with the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model to estimate flood frequency analysis. The results of these frequency analyses can be compared against the results of conventional methods such as the NOAA Atlas 14 precipitation frequency estimates and peak discharge estimates prepared by FEMA and the North Carolina state government.

  10. 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.

  11. Impact of complexity of radar rainfall uncertainty model on flow simulation

    NASA Astrophysics Data System (ADS)

    Dai, Qiang; Han, Dawei; Zhuo, Lu; Huang, Jing; Islam, Tanvir; Srivastava, Prashant K.

    2015-07-01

    A large number of radar rainfall uncertainty (RRU) models have been proposed due to many error sources in weather radar measurements. It is recognized that these models should be integrated into overall uncertainty analysis schemes with other kinds of model uncertainties such as model parameter uncertainty when the radar rainfall is applied in hydrological modeling. We expect that the RRU model can be expressed in a mathematically extensible and simple format. However, the complexity of the RRU has been growing as more and more factors are considered such as spatio-temporal dependence and non-Gaussian distribution. This study analyzes how the RRU propagates through a hydrological model (the Xinanjiang model) and investigates which features of the RRU model have significant impacts on flow simulation. A RRU model named Multivariate Distributed Ensemble Generator (MDEG) is implemented in the Brue catchment in England under different model complexities. The generated ensemble rainfall values by MDEG are then input into the Xinanjiang model to produce uncertainty bands of ensemble flows. Comparison of five important indicators that describe the characteristics of uncertainty bands shows that the ensemble flows generated by MDEG with non-Gaussian marginal and joint distributions are close to the ones with Gaussian distributions. In addition, the dispersion of the uncertainty bands increases dramatically with the growth of the MDEG model complexity. It is concluded that the Gaussian marginal distribution and spatio-temporal dependence using Gaussian copula is considered to be the preferred configuration of the MDEG model for hydrological model uncertainty analysis. Further studies should be carried out in a variety of catchments under different climate conditions and geographical locations to check if the conclusion is valid beyond the Brue catchment under the British climate.

  12. Comparison between radar and rain gauges data at different distances from radar and correlation existing between the rainfall values in the adjacent pixels

    Microsoft Academic Search

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

    2010-01-01

    Rainfall intensity data in pixels very far from radar are less correlated than values in pixels near the radar, because at far distances the width of a range-bin is comparable or bigger than the pixel width, so in a pixel there are one or just a few rainfall intensity values. Vice versa, near the radar, there are many radar resolution

  13. Development of Weather Radar Mosaic Products in the U.S. National Weather Service

    Microsoft Academic Search

    D. H. Kitzmiller; S. Guan; C. Mello; J. Dai

    2002-01-01

    The Weather Surveillance Radar 1988 (Doppler) (WSR-88D) network contains 142 units within the conterminous United States, 7 units in Alaska, and 4 units in Hawaii. The units are maintained by several agencies of the federal government, including the National Weather Service, the Federal Aviation Administration, and the Department of Defense. Many users of the data require access to observations from

  14. Heft 121 Uwe Ehret Rainfall and Flood Nowcasting in

    E-print Network

    Cirpka, Olaf Arie

    Heft 121 Uwe Ehret Rainfall and Flood Nowcasting in Small Catchments using Weather Radar #12;Rainfall and Flood Nowcasting in Small Catchments using Weather Radar Von der Fakultät Bau- und. Oktober 2002 Institut für Wasserbau der Universität Stuttgart 2003 #12;Heft 121 Rainfall and Flood

  15. Estimation of Rainfall Based on the Results of Polarimetric Echo Classification

    Microsoft Academic Search

    Scott E. Giangrande; Alexander V. Ryzhkov

    2008-01-01

    Accurate rainfall estimates are vital for most hydrologic applications. The U.S. National Weather Service (NWS) requires estimates of rainfall at ranges up to 230 km from the radar. However, the quality of radar rainfall estimates degrades with distance as a result of beam broadening, the effect of Earth curvature, and overshooting precipitation. At longer distances from the radar, the radar

  16. A Variational Scheme for Retrieving Rainfall Rate and Hail Reflectivity Fraction from Polarization Radar

    E-print Network

    Hogan, Robin

    Radar ROBIN J. HOGAN Department of Meteorology, University of Reading, Reading, United Kingdom (Manuscript received 30 June 2006, in final form 17 January 2007) ABSTRACT Polarization radar offers the promise of much more accurate rainfall-rate R estimates than are possible from radar reflectivity factor Z

  17. An update on the multi-channel phased array Weather Radar at the National Weather Radar Testbed

    Microsoft Academic Search

    M. Yeary; G. Crain; A. Zahrai; R. Kelley; J. Meier; Y. Zhang; I. Ivic; C. Curtis; R. Palmer; T.-Y. Yu; R. Doviak

    2011-01-01

    The first phased array radar dedicated to weather observation and analysis is now instrumented with eight, simultaneous digital receivers. The multi-channel receiver will collect signals from the sum, azimuth-difference, elevation- difference, and five broad-beamed auxiliary channels. The multi-channel receiver will allow the direct implementation of interferometry techniques to estimate crossbeam wind, shear and turbulence within a radar resolution volume. Access

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

    Microsoft Academic Search

    Steven M. Bolen; V. Chandrasekar

    2003-01-01

    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

  19. 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 resolution real-time model simulations possible, the need to obtain observations to both initialize numerical models and verify their output has become increasingly important. The assimilation of high resolution radar observations therefore provides a vital component in the development and utility of numerical model forecasts for both weather forecasting and contaminant transport, including future opportunities to improve wet deposition computations explicitly.

  20. GNU Radio based software-defined FMCW radar for weather surveillance application

    Microsoft Academic Search

    Aditya Prabaswara; Achmad Munir; Andriyan Bayu Suksmono

    2011-01-01

    In this paper, a GNU Radio based software-defined FMCW (Frequency Modulated — Continuous Wave) radar is studied for weather surveillance application. The FMCW radar that has been gaining popularity due to the use of solid state microwave amplifier to generate a signal source is proposed for the design since the current weather surveillance radar is usually using a pulse-radar type

  1. Multichannel Receiver Design, Instrumentation, and First Results at the National Weather Radar Testbed

    Microsoft Academic Search

    Mark Yeary; Gerald Crain; Allen Zahrai; Christopher D. Curtis; John Meier; Redmond Kelley; Igor R. Ivic; Robert D. Palmer; Richard J. Doviak; G. Zhang; Tian-You Yu

    2012-01-01

    When the National Weather Radar Testbed (NWRT) was installed in 2004, a single-channel digital receiver was implemented so that the radar could mimic typical Weather Surveillance Radar (WSR) version 1988 Doppler (WSR-88D) capability. This, however, left unused eight other channels, built into the antenna. This paper describes the hardware instrumentation of a recently completed project that digitizes the radar signals

  2. Volcanic Ash Cloud Retrieval by Ground-Based Microwave Weather Radar

    Microsoft Academic Search

    Frank Silvio Marzano; Stefano Barbieri; Gianfranco Vulpiani; William I. Rose

    2006-01-01

    The potential of ground-based microwave weather radar systems for volcanic ash cloud detection and quantitative retrieval is evaluated. The relationship between radar reflectivity factor, ash concentration, and fall rate is statistically derived for various eruption regimes and ash sizes by applying a radar-reflectivity microphysical model. To quantitatively evaluate the ash detectability by weather radars, a sensitivity analysis is carried out

  3. Defeating the Doppler Dilemma : Space Physics Meets Weather Radar

    Microsoft Academic Search

    James Stagliano

    2002-01-01

    The Doppler Dilemma is the embodiment of the Shannon Information Theorem and defines a fundamental inverse relationship upon the simultaneous detection of range and velocity. Much research in signal processing techniques in the weather radar community has centered on overcoming the Doppler Dilemma. The most promising work employs methods originally developed in space physics, particularly ionospheric research. In this paper,

  4. Statistical problems with weather-radar images, II: Attenuation detection

    Microsoft Academic Search

    Juan-José Fernández-Durán; Graham Upton

    2003-01-01

    A procedure based on the combination of a Bayesian changepoint model and ordinary least squares is used to identify and quantify regions where a radar signal has been attenuated (i.e.diminished) as a consequence of intervening weather. A graphical polar display is introduced that illustrates the location and importance of the attenuation.

  5. Detection of Small Aircraft with Doppler Weather Radar

    Microsoft Academic Search

    Svetlana Bachmann; Victor DeBrunner; Dusan Zrnic

    2007-01-01

    We present a method that can be performed in parallel to reflectivity estimation in weather radar and that allows one to detect small aircraft. Though small aircraft and large birds might produce comparable reflectivity signals their spectral signatures are considerably different. A small aircraft with propellers can be recognized from its spectrum via modulations produced by Doppler shifts from rotating

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

    Microsoft Academic Search

    Svetlana Monakhova Bachmann

    2007-01-01

    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

  7. Spatial and temporal analysis of weather radar reflectivity images

    Microsoft Academic Search

    Mark W. Merritt

    1987-01-01

    This paper illustrates the use of a primitive symbolic description of an image to obtain more robust identification of amorphous objects than would be possible with more conventional edge or gradient-based segmentation techniques. An algorithm is described which uses a simple multi-level thresholding operation to form a symbolic representation of weather radar reflectivity images. This representation allows the use of

  8. Application of LSS-decomposition in weather radar signal processing

    Microsoft Academic Search

    O. S. Semenova; F. J. Yanovsky; I. V. Shelevytsky

    2012-01-01

    In this paper new approach for weather radar signal analysis and dangerous meteorological zones detection is discussed. It is based on time-frequency LSS decomposition. In order to provide reliable information about the object location and its intensity, the confidence intervals calculation is fulfilled.

  9. Water Utility Makes Use of National Weather Service Radar

    Microsoft Academic Search

    Stephen C. Gerwin

    1987-01-01

    The Washington Suburban Sanitary Commission (WSSC) has tied into the National Weather Service radar system to take measures against the disruptions in water service caused by power outages during frequent severe summer thunderstorms. Advance warnings of potential outages enable the utility to fill elevated storage tanks to maximal capacities, and pumping can be done during offpeak periods when electric rates

  10. The WSR-88D Rainfall Algorithm

    Microsoft Academic Search

    Richard A. Fulton; Jay P. Breidenbach; Dong-Jun Seo; Dennis A. Miller; Timothy O’Bannon

    1998-01-01

    A detailed description of the operational WSR-88D rainfall estimation algorithm is presented. This algorithm, called the Precipitation Processing System, produces radar-derived rainfall products in real time for forecasters in support of the National Weather Service's warning and forecast missions. It transforms reflectivity factor measurements into rainfall accumulations and incorporates rain gauge data to improve the radar estimates. The products are

  11. 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 propagated through the model to assess its influence on the forecasted flow uncertainty. Furthermore, the effects of uncertainties at different forecast lead times on potential abstraction strategies are assessed. The results show that over a 10 year period, an average of approximately 70 ML/d of potential water is missed in the study catchment under a convention abstraction regime. This indicates a considerable potential for the use of flow forecasting models to effectively implement advanced abstraction management and more efficiently utilize available water resources in the study catchment.

  12. 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.

  13. Adaptive algorithms for Doppler weather radar

    Microsoft Academic Search

    I. G. Prokopenko; K. I. Prokopenko; F. J. Yanovsky; L. P. Ligthart

    2005-01-01

    New complex adaptive algorithms of detection and measurement of turbulence intensity in weather formations are proposed. Algorithms are based on calculation of spectrum estimations by using the signals reflected from the adjacent range bins. Statistical hypothesis about the difference between the adjacent or next spectra are checked. The decision-making on distinction of spectra is done by the estimation of RMS

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

    NASA Astrophysics Data System (ADS)

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

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

  15. Evaluation of Raindrop Size Distributions to Improve Radar Rainfall Estimation during the Colorado Flood

    NASA Astrophysics Data System (ADS)

    Kucera, Paul; Klepp, Christian

    2014-05-01

    During the period of 9-16 September 2013, a large area of greater than 150 mm of rain, with local amounts of up to 450 mm, fell over a large part of the Colorado Front Range foothills and adjacent plains. This extreme rainfall event caused severe flooding of main river channels and some localized flash flooding which resulted in millions of dollars of damage to private and public properties. The rainfall regime associated with this extreme precipitation event was atypical of storms usually observed in this region. As a result, the radar rainfall algorithms tuned for this region significantly underestimated the total amount of rainfall. In order to quantify the underestimation and provide insight for improving the radar rainfall estimates for this unique precipitation regime, a comparison study has been conducted using data from several disdrometers that were operating throughout the event. Disdrometers observed over 5000 minutes of rainfall during the event. Analysis of the raindrop spectra indicated that most of the rainfall was comprised of a large number of small drops (< 2 mm in diameter). The raindrop spectra have been stratified by the precipitation regime. For these different regimes, new radar rainfall estimators are being derived from the raindrop spectra. The new estimators will be applied to the radar data to provide new rainfall estimates. These estimates will be evaluated using independent rain gauge data. The presentation will provide an overview of the Colorado Flood and a summary of results from the precipitation analysis.

  16. Near Real-Time Runoff Estimation Using Spatially Distributed Radar Rainfall Data

    E-print Network

    Hadley, Jennifer Lynn

    he purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number (CN) method for estimating near real-time runoff for naturalized flow, using high resolution radar rainfall data for watersheds...

  17. Specification of predictors necessary for the determination of over or underestimation of radar derived total rainfall 

    E-print Network

    Holbrook, Vincent Patrick

    1987-01-01

    over or underestimation of radar determined rainfall rates. Two radar sampling procedures, systematic and irregu- lar, were employed against light and heavy rain events to calculate rainfall rates for 10 km x 10 km grid boxes. Sampling intervals used... . . . . . . . . . . . b. Initial set of predictors. . . . . . . . . 1) Underestimation . . . . . . . 2) Overestimation. . c. The reduced set of predictors. . . d. Results. . . 1) Underestimation . . a) Light rain . . . . . . . . . . . b) Heavy rain . . 2...

  18. Comparison between radar and rain gauges data at different distances from radar and correlation existing between the rainfall values in the adjacent pixels

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    Rainfall intensity data in pixels very far from radar are less correlated than values in pixels near the radar, because at far distances the width of a range-bin is comparable or bigger than the pixel width, so in a pixel there are one or just a few rainfall intensity values. Vice versa, near the radar, there are many radar resolution bins which belong to a single pixel, so great correlation between rainfall intensity values for contiguous pixels is expected. Moreover, the signal returned from precipitation at far distance from radar antenna can be due to a radar sample volume partially or completely filled with mixed phase or ice particles, or can be quite close to the minimum detectable signal. All these phenomena can influence the goodness of rainfall estimates, introducing errors which increase as the distance from radar increases. The objective of this work is to characterize these errors as a function of the distance. For this aim is possible to compare the rainfall data obtained by rain gauges at different distances from radar with rainfall radar data at the same distances, verifying the correlation existing between the rainfall values in the adjacent pixels and how the difference between radar and rain gauges data changes. The radar data utilized in this work have been collected from the CNR-ISAC (Institute of Atmospheric Sciences and Climate of the National Research Council) Polar 55C radar in Rome Tor Vergata during 2008.

  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 Hydrometeorology 6: 532-549 http://dx.doi.org/10.1175/JHM433.1 Berenguer M, D Sempere, G Pegram, 2011: SBMcast - An ensemble nowcasting technique to assess the uncertainty in rainfall forecasts by Lagrangian extrapolation. Journal of Hydrology 404: 226-240 http://dx.doi.org/10.1016/j.jhydrol.2011.04.033

  20. A Time Series Weather Radar Simulator Based on High-Resolution Atmospheric Models

    Microsoft Academic Search

    B. L. Cheong; R. D. Palmer; M. Xue

    2008-01-01

    A three-dimensional radar simulator capable of generating simulated raw time series data for a weather radar has been designed and implemented. The characteristics of the radar signals (amplitude, phase) are derived from the atmospheric fields from a high-resolution numerical weather model, although actual measured fields could be used. A field of thousands of scatterers is populated within the field of

  1. Some Techniques for Three-dimensional Doppler Weather Radar Data Processing

    Microsoft Academic Search

    Pu Zhang; Hong Shu; Yan Liu; Yang Li

    2006-01-01

    In this paper, we develop some techniques for three- dimensional Doppler weather radar data processing. These techniques are mainly used for Doppler weather radar data preprocessing, data resampling, data storage, and data visualization. A median filter is employed to remove data singularity and make data smooth. Radar data in the spherical coordinate system is transformed into data in the Cartesian

  2. Clutter cancellation in a weather radar using an adaptive array antenna

    Microsoft Academic Search

    Jonggil Lee

    2008-01-01

    High resolution windspeed profile measurements are needed in a weather radar to provide the reliable information of rapidly changing weather conditions. The commonly used pulse pair method is quite attractive when processing an enormous amount of weather radar data in real time since it is considered the fastest algorithm available[1] [2] [3] [4]. However, it is necessary to remove both

  3. METR 4624--Radar Meteorology SPRING 2012

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2012 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  4. METR 4624--Radar Meteorology SPRING 2014

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2014 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  5. Real-time Kriging Correction for Radar Rainfall: A Case Study in Central Taiwan

    NASA Astrophysics Data System (ADS)

    Yang, T.; Chen, C.; Kuo, C.; Chen, W.; Yu, P.

    2011-12-01

    This study aimed to correct the error of the radar rainfall by using the Kriging method in real-time. Rainfall is the key for hydrological researches. The error of the rainfall data may cause the inaccuracy of the runoff estimation of the watershed. Although the raingauge observations can provide accurate precipitation, the sparse spatial resolution of the raingauge network cannot represent the actual rainfall in the ungauged area. The development of radar precipitation has brought the convenience for people to have a better understanding of the spatial distribution of the precipitation. However, the radar rainfall in Taiwan showed very low accuracy while compared with the raingauge data. Thus, the real-time correction of the radar precipitation is necessary before further application. The Kriging method was used to correct the radar precipitation to fit the raingauge observation. The Dajia River basin was chosen as the study area. The radar rainfall and raingauge data of 13 typhoons during 2005-2009 were collected. Thirty-five raingauge stations were chosen as the calibration stations to establish the error distribution. Other 5 raingauge stations were used to validate the correction. For each time step, the Kriging method was applied individually to achieve the real-time correction. The error of the calibration dataset was normalized to interval [0,1] first. Next, the experimental semivariogram was generated from the calibration stations. The sill and range of the spherical model from the experimental semivariogram were searched automatically. Then, the error distribution was calculated by using the GSLIB geostatistics software with input of the normalized errors, sill and range. Finally, the errors of the validation stations were de-normalized from the error distribution. According to the performance index, the correlation coefficient increased from 0.6 to 0.9 and the RMSE dropped from 8.5 to 0.7 after Kriging correction. So, we concluded that Kriging method has the ability to improve the radar rainfall.

  6. The Influence of Meteorological Parameters on Rainfall and Severe Weather in Pinellas County, FL

    Microsoft Academic Search

    Cristina A. Mazza

    2011-01-01

    Pinellas County is located on a peninsula in Florida that experiences daily patterns of sea breeze associated rainfall mainly during the summer months of June through August. Previously, rainfall patterns, amounts and timing and severe weather in Pinellas County have not been examined considering dominant wind flow patterns, sea breeze circulations and other atmospheric variables. To improve forecasting of local

  7. 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 precipitation, the surface return over a single 360 degree sweep over -25 h-diameter region provides information on the surface wind speed and direction within the scan circle. In precipitation regions, the conical scan with appropriate mapping and analysis provides the 3D structure of reflectivity beneath the plane and the horizontal winds. The use of conical scanning in hurricanes has recently been demonstrated for measuring inner core winds with the IWRAP system flying on the NOAA P3's. In this presentation, we provide a description of the URAD system hardware, status, and future plans. In addition to URAD, NASA SBIR activity is supporting a Phase I study by Remote Sensing Solutions and the University of Massachusetts for a dual-frequency IWRAP for a high altitude UAV that utilizes solid state transmitters at 14 and 35 GHz, the same frequencies that are planned for the radar on the Global Precipitation System satellite. This will be discussed elsewhere at the meeting.

  8. Investigating radar subpixel-scale rainfall variability and uncertainty from observations of a super dense rain-gauge network

    NASA Astrophysics Data System (ADS)

    Peleg, Nadav; Ben-Asher, Matan; Morin, Efrat

    2014-05-01

    Runoff and flash flood generation are very sensitive to rainfall's spatial and temporal variability. The increasing use of radar and satellite data in hydrological applications, due to the sparse distribution of rain gauges over most catchments worldwide, requires furthering our knowledge of the uncertainties of these data. In 2011, a new super-dense network of rain gauges, containing 27 gauges covering an area of about 4 km2, was installed in northern Israel, representing Mediterranean climate regime. This network was established for a detailed exploration of the uncertainties associated with radar and satellite rainfall resulting from rainfall variability at the subpixel-scale. The gauge-rainfall spatial correlation and uncertainty were examined along with the estimated radar error. The zero-distance correlation between rain gauges was high (0.92 on the 1-min scale) and increased as the time scale increased. A difference was detected in the spatial correlations of the convective and nonconvective rainfall, as the convective rainfall correlation decreases much faster than the nonconvective one. The variance of the differences between radar pixel rainfall and averaged point rainfall (the variance reduction factor) was 1.6% for the 1-min scale. It was also found that at least four uniformly distributed rain stations are needed to adequately represent the rainfall on the radar pixel scale. The radar-rain gauge rainfall difference was mainly contributed by radar estimation errors while the gauge sampling error contributed no more than 22% to the total error. The radar rainfall estimations improved with increasing time scale and the radar-to-true rainfall ratio decreased with increasing time scale. The analysis of the radar errors and uncertainties suggest that a temporal scale of at least 10 min should be used for hydrological applications of the radar data.

  9. Rainfall generator for the Rhine basin: multi-site simulation of daily weather variables by nearest-neighbour resampling

    E-print Network

    Beersma, Jules

    Rainfall generator for the Rhine basin: multi-site simulation of daily weather variables by nearest (KMNI) Abstract Nearest-neighbour resampling is used here for the joint simulation of daily rainfall rainfall over the drainage basin and the dependence between daily rainfall and temperature without making

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  11. Impact of satellite rainfall assimilation on Weather Research and Forecasting model predictions over the Indian region

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Kishtawal, C. M.; Pal, P. K.

    2014-03-01

    Rainfall is probably the most important parameter that is predicted by numerical weather prediction models, though the skill of rainfall prediction is the poorest compared to other parameters, e.g., temperature and humidity. In this study, the impact of rainfall assimilation on mesoscale model forecasts is evaluated during Indian summer monsoon 2011. The Weather Research and Forecasting (WRF) model and its four-dimensional variational data assimilation system are used to assimilate the Tropical Rainfall Measuring Mission 3B42 and Japan Aerospace Exploration Agency Global Satellite Mapping of Precipitation retrieved rainfall. A total of five experiments are performed daily with and without assimilation of rainfall data during the entire month of July 2011. Separate assimilation experiments are performed to assess the sensitivity of WRF model forecast with strict and less strict quality control. Assimilation of rainfall improves the forecast of temperature, specific humidity, and wind speed. Domain average improvement parameter of rainfall forecast is also improved over the Indian landmass when compared with NOAA Climate Prediction Center Morphing technique and Indian Meteorological Department gridded rainfall.

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

    Microsoft Academic Search

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

    2001-01-01

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

  13. Signal Processing Algorithms for the Terminal Doppler Weather Radar: Build 2

    E-print Network

    Cho, John Y. N.

    Signal Processing Algorithms for the Terminal Doppler Weather Radar: Build 2 February 21, 2010 John to the public through the National Technical Information Service, Springfield, VA 22161 Signal Processing) was developed for the Terminal Doppler Weather Radar (TDWR), enhanced signal processing algorithms taking

  14. Suppression of Clutter Residue in Weather Radar Reveals Birds' Corridors Over Urban Area

    Microsoft Academic Search

    Svetlana M. Bachmann; Dusan S. Zrnic

    2008-01-01

    An adaptive spectral technique for ground clutter and noise suppression in weather radar echoes is presented. This technique detects weak echoes that are masked by the residuals from ground clutter. The technique is demonstrated on two clear air cases observed with Doppler weather radar. After adaptive suppression of ground clutter and its residue, features appear over the Oklahoma City urban

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

    Microsoft Academic Search

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

    2009-01-01

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

  16. SEVIRI rainfall retrieval and validation using weather radar observations

    Microsoft Academic Search

    R. A. Roebeling; I. Holleman

    2009-01-01

    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

  17. 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 of the Island (relief, ocean distance, etc.) with a 1-km2 spatial resolution. For return periods of up to 10 years, the SHYREG-estimated rainfall frequency values are consistent with estimates from the GPD law according to the Nash-Sutcliffe criteria. For extreme return periods, we validate SHYREG-based rainfall frequency estimates according to criteria of reliability and stability3 and compare with the GPD performance. The stability of the frequency analysis method is defined by its capacity to produce similar results when calibrated with different data samples, its reliability by its capacity to assign accurate probabilities of occurrence to observations. Results from applying both criteria have shown that the SHYREG method is highly stable and reliable compared to the GPD law.

  18. Machine-intelligent approach to automated gust-front detection for Doppler weather radars

    Microsoft Academic Search

    Seth W. Troxel; Richard L. Delanoy

    1994-01-01

    Automated gust front detection is an important component of the airport surveillance radar with wind shear processor (ASR-9 WSP) and terminal Doppler weather radar (TDWR) systems being developed for airport terminal areas. Gust fronts produce signatures in Doppler radar imagery which are often weak, ambiguous, or conditional, making detection and continuous tracking of gust fronts challenging. A machine intelligent gust

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

    Microsoft Academic Search

    I. Emmanuel; H. Andrieu; P. Tabary

    The main objective of this paper is to evaluate, at the urban scale, the accuracy of the new French operational radar processing chain deployed within the French operational weather radar network. Such an evaluation is conducted by comparing radar data resulting from this processing chain (with a 1-km2 resolution) to rain gauge data at four different time scales, i.e. 5,

  20. 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 reduces the complexity from "NxN" transmit/receive (T/R) modules of a conventional planar-phased array to just "N" T/R modules. The antenna uses T/R modules with electronic phase-shifters for beam steering. The offset reflector does not provide poor cross-polarization like a double- curved offset reflector would, and it allows the wide scan angle in one plane required by the mission. Also, the cylindrical reflector with two linear array feeds provides dual-frequency performance with a single, shared aperture. The aperture comprises a reflective surface with a focal length of 1.89 m and is made from aluminized Kapton film. The reflective surface is of uniform thickness in the range of a few thousandths of an inch and is attached to the chain-link support structure via an adjustable suspension system. The film aperture rolls up, together with the chain-link structure, for launch and can be deployed in space by the deployment of the chain-link structure.

  1. 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 for interactive data exploration and analysis. Based on the powerful scientific python stack (numpy, scipy, matplotlib) and in parts augmented by functions compiled in C or Fortran, most routines are fast enough to also allow data intensive re-analyses or even real-time applications. From the organizational point of view, wradlib is intended to be community driven. To this end, the source code is made available using a distributed version control system (DVCS) with a publicly hosted repository. Code may be contributed using the fork/pull-request mechanism available to most modern DVCS. Mailing lists were set up to allow dedicated exchange among users and developers in order to fix problems and discuss new developments. Extensive documentation is a key feature of the library, and is available online at http://wradlib.bitbucket.org. It includes an individual function reference as well as examples, tutorials and recipes, showing how those routines can be combined to create complete processing workflows. This should allow new users to achieve results quickly, even without much prior experience with weather radar data.

  2. Radar studies of heavy convective rainfall in mountainous terrain

    NASA Astrophysics Data System (ADS)

    Landel, Gregoire; Smith, James A.; Baeck, Mary Lynn; Steiner, Matthias; Ogden, Fred L.

    1999-01-01

    Heavy rainfall, topography, storm motion, and storm evolution are closely linked for four storms that produced catastrophic flooding along the Front Range of the Rocky Mountains and the east slope of the Blue Ridge Mountains. Storms selected for detailed study in this paper are the Rapidan storm of June 27, 1995, the Fort Collins storm of July 28, 1997, the Buffalo Creek storm of July 12, 1996, and the Monocacy storm of June 18, 1996. The Buffalo Creek storm and the Fort Collins storm occurred in the Front Range of the Rocky Mountains in Colorado; the Rapidan and Monocacy storms occurred along the east slopes of the Blue Ridge of Virginia and southern Pennsylvania. The four storms caused catastrophic flooding at drainage basin scales between 1 and 1000 km2. The scale of flood response for these events imposes a need to characterize rainfall variability at very fine space scales and timescales, of the order of 1 km spatial scale and 1-5 min timescale. A fundamental issue for the hydrometeorology of extreme rainfall in mountainous terrain is whether anomalously large rainfall accumulations in orographic convection result from anomalously slow net storm motion, anomalously large rainfall rates, or both. Anomalous storm motion and processes resulting in catastrophic rainfall rates are examined for each of the four storms. Of particular importance for anomalous storm motion in orographic convection are interactions between the low-level wind field and terrain features.

  3. Weather Radar and Hydrology (Proceedings of a symposium held in Exeter, UK, April 2011) (IAHS Publ. 3XX, 2011).

    E-print Network

    Reading, University of

    Weather Radar and Hydrology (Proceedings of a symposium held in Exeter, UK, April 2011) (IAHS Publ. 3XX, 2011). Copyright 2011 IAHS Press 1 Operational Radar Refractivity Retrieval for Numerical describes the application of radar refractivity retrieval to the C-band radars of the UK operational weather

  4. P11B.1 A VARIATIONAL SCHEME FOR RETRIEVING RAINFALL RATE AND HAIL REFLECTIVITY FRACTION FROM POLARIZATION RADAR

    E-print Network

    Hogan, Robin

    POLARIZATION RADAR ROBIN J. HOGAN Department of Meteorology, University of Reading, United Kingdom ABSTRACT Polarization radar offers the promise of much more accurate rainfall rate (R) estimates than possible from radar reflectivity factor (Z) alone, not only by better characterization of the drop size distribution

  5. A study of the applicability of weather radar in streamflow forecasting 

    E-print Network

    Curry, Robert Gene

    1970-01-01

    CONCLUSIONS AND RECOMMENDATIONS ~ 42 46 LIST OF REFERENCES . . . . . . . . , . ~ 48 VITA . ~ 50 vii LIST OF TABLES Table Ti. tie Adjustment factors required to yield observed runoff. from radar rainfall 15 Comparison of "Radar" rainfall and rain gaga... Title Page Location of rain gages . . . . . . . . . . . . . 4 Example of isoecho analysis. R values are in mm/hr. . . . . . . . . . . . . . . . . . . 16. Some possible water-surface profiles during passage of a flood wave ~ . . . . . . , . . . 20...

  6. Analysis of cross-beam resolution effects in rainfall rate profile retrieval from a spaceborne radar

    Microsoft Academic Search

    Paul Amayenc; Mongi Marzoug; Jacques Testud

    1993-01-01

    The performance (stability and accuracy) of a range profiling algorithm (kZS), using the measurement of surface echo as a constraint on total path integrated attenuation, for rainfall retrieval from a spaceborne radar was presented and discussed by C. Matzler (1987). Omitting other causes of errors previously examined, the present authors focus specifically on possible bias due to nonuniform beam filling

  7. Analysis Of Crossbeam Resolution Effects In Rainfall Rate Profile Retrieval From A Spaceborne Radar

    Microsoft Academic Search

    P. Amayenc; M. Marzoug; J. Testud

    1990-01-01

    The performances (stability and accurracy) of a new range profiling algorithm (US), using the path integrated attenuation as a constraint, for rainfall retrieval from a spacebome radar is presented in a companion paper (this issue). Omitting other causes of errors previously examined, the present paper focuses specifically on possible bias due to non uniform beam filling effects. This problem is

  8. Stormwater inflow prediction using radar rainfall data compressed by principal component analysis

    Microsoft Academic Search

    K. Katayama; K. Kimijima; O. Yamanaka; A. Nagaiwa; Y. Ono

    This paper proposes a method of stormwater inflow prediction using radar rainfall data as the input of the prediction model constructed by system identification. The aim of the proposal is to construct a compact system by reducing the dimension of the input data. In this paper, Principal Component Analysis (PCA), which is widely used as a statistical method for data

  9. Development of Weather Radar Mosaic Products in the U.S. National Weather Service

    NASA Astrophysics Data System (ADS)

    Kitzmiller, D. H.; Guan, S.; Mello, C.; Dai, J.

    2002-05-01

    The Weather Surveillance Radar 1988 (Doppler) (WSR-88D) network contains 142 units within the conterminous United States, 7 units in Alaska, and 4 units in Hawaii. The units are maintained by several agencies of the federal government, including the National Weather Service, the Federal Aviation Administration, and the Department of Defense. Many users of the data require access to observations from multiple radars simultaneously, and various mechanisms have beendevised to create national- and regional-scale geographic composites. Within the National Weather Service, creation of mosaics at local forecast offices can take up a substantial portion of available computing resources. The Meteorological Development Laboratory has undertaken the development of a system that will centrally produce and disseminate a set of mosaic products covering the conterminous United States, thus reducing the need for local production of the products. The effort has been made possible by the recent completion of communications network upgrades that permit rapid central collection of data from all sites within the WSR-88D network. A review of the radar product suite will be presented. The suite presently includes reflectivity, precipitation ccumulation estimates, vertically-integrated liquid water estimates, 18-dBZ echo top heights, and convective storm cell information such as hail indications and Doppler indications of mesocyclones and tornadoes. The operational goal is the production of mosaics at approximately 2-km spatial resolution for reflectivity and 4-km resolution for other fields, on a 5-minute update cycle. Some products are currently made available in graphical format via the World-Wide Web. Substantial progress has been made in developing an automated procedure to identify nonprecipitation echoes, including birds, insects, ground clutter, and anomalous propagation. Tests comparing the outcome of automated target identification with manual identification will be presented.

  10. 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.

  11. 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.

  12. 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.

  13. Weather radar equation and a receiver calibration based on a slice approach

    NASA Astrophysics Data System (ADS)

    Yurchak, B. S.

    2012-12-01

    Two circumstances are essential when exploiting radar measurement of precipitation. The first circumstance is a correct physical-mathematical model linking parameters of a rainfall microstructure with a magnitude of a return signal (the weather radar equation (WRE)). The second is a precise measurement of received power that is fitted by a calibration of radar receiver. WRE for the spatially extended geophysical target (SEGT), such as cloud or rain, has been derived based on "slice" approach [1]. In this approach, the particles located close to the wavefront of the radar illumination are assumed to produce backscatter that is mainly coherent. This approach allows the contribution of the microphysical parameters of the scattering media to the radar cross section to be more comprehensive than the model based on the incoherent approach (e.g., Probert-Jones equation (PJE)). In the particular case, when the particle number fluctuations within slices pertain the Poisson law, the WRE derived is transformed to PJE. When Poisson index (standard deviation / mean number of particles) of a slice deviates from 1, the deviation of return power estimated by PJE from the actual value varies from +8 dB to - 12 dB. In general, the backscatter depends on mean, variance and third moment of the particle size distribution function (PSDF). The incoherent approach assumes only dependence on the sixth moment of PSDF (radar reflectivity Z). Additional difference from the classical estimate can be caused by a correlation between slice field reflectivity [2]. Overall, the deviation in particle statistics of a slice from the Poisson law is one of main physical factors that contribute to errors in radar precipitation measurements based on Z-conception. One of the components of calibration error is caused by difference between processing by weather radar receiver of the calibration pulse, and actual return signal from SEGT. A receiver with non uniform amplitude-frequency response (AFR) processes these signals with the same input power but with different radio-frequency spectrums (RFS). This causes different output magnitude due to different distortion experienced while RFS passing through a receiver filter. To assess the calibration error, RFS of signals from SEGT has been studied including theoretical, experimental and simulation stages [3]. It is shown that the return signal carrier wave is phase modulated due to overlapping of replicas of RF-probing pulse reflected from SEGT's slices. The RFSs depends on the phase statistics of the carrier wave and on RFS of the probing pulse. The bandwidth of SEGT's RFS is not greater than that of the probing pulse. Typical phase correlation interval was found to be around the same as that of the probing pulse duration. Application of a long calibration signal (proportional to SEGT extension) causes the error up to -1 dB for conventional radar with matched filter. To eliminate the calibration error, a power estimate of individual return waveform should be corrected with the transformation loss coefficient calculated based on RFS and AFR parameters. To embrace with calibration the high and low frequency parts of a receiver, the calibration should be performed with a long pulse. That long pulse is composed from adjoining replicas of a probe pulse with random initial phases and having the same magnitude governed by the power of probe pulse.

  14. 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-? 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-? gram, CAPE.

  15. 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 instrument development costs. In the second portion of this paper, we will present a system concept for a geostationary rainfall monitoring radar for operations at the geosynchronous Earth Orbit (GEO). In particular, the science requirements, the observational strategy, the instrument design, and the required technologies will be discussed.

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

    NASA Astrophysics Data System (ADS)

    Li, Y.; Kuligowski, R. J.

    2010-12-01

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

  17. Spatial-temporal rainfall elds: modelling and statistical aspects H.S. Wheater1

    E-print Network

    Guillas, Serge

    Spatial-temporal rainfall elds: modelling and statistical aspects H.S. Wheater1 V.S. Isham2 D weather radar systems may pro tably be exploited to study the rainfall process, with particular emphasis network of raingauges available for studying the rainfall at a ne local scale and a network of radar

  18. 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.

  19. Nonlinear Modeling of Radar-Rainfall Errors at Different Time Scales

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  20. The use of composite radar photographs in synoptic weather analysis 

    E-print Network

    Smith, G. D.

    1957-01-01

    sre in the form of composite : radar PPZ photographs . . =. k= symbology is. suggested for ds~ioting the gross features of the radar precipitation echoee. The symbology can be used to indicate echo analysis of PPX photographs and to plo? radar data... phccograph ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ? ~ ~ 4 Composite radar photograph . 4' Spnergiea ~ ~ ~ ~ ~ ~ ~ e ~ ~ ~ ~ ~ i ~ ~ e ~ ~ ~ Echo line ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ echo ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Handed XneCabilitP line...

  1. ERAD 2012 -THE SEVENTH EUROPEAN CONFERENCE ON RADAR IN METEOROLOGY AND HYDROLOGY Scaling properties of rainfall and their impact on

    E-print Network

    Paris-Sud XI, Université de

    , C. Mallet1 1Université Versailles Saint-Quentin ­ CNRS/INSU ­ LATMOS/IPSL, 11 bd d'Alembert 78280 Guyancourt, France, contact : verrier@latmos.ipsl.fr 1. Introduction Radar rainfall estimates are generally

  2. Threshold Calculation for Coherent Detection in Dual-Polarization Weather Radars

    Microsoft Academic Search

    Igor R. Ivic; Dusan S. Zrnic; Tian-You Yu

    2012-01-01

    It is customary to censor signals in conventional weather radar using estimates of signal-to-noise ratio (SNR) and\\/or magnitude of autocorrelation coefficient at lag one. Dual-polarized weather radar provides a pair of highly correlated signals from the two orthogonally polarized returns. A novel censoring technique, previously proposed, sums powers, autocorrelations, and correlation between signals in the two channels and compares the

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

    Microsoft Academic Search

    Steven V. Vasiloff

    2001-01-01

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

  4. Iterative Bayesian Retrieval of Hydrometeor Content From X-Band Polarimetric Weather Radar

    Microsoft Academic Search

    Frank Silvio Marzano; Giovanni Botta; Mario Montopoli

    2010-01-01

    Dual-polarized weather radars are capable to detect and identify different classes of hydrometeors, within stratiform and convective storms, exploiting polarimetric diversity. Among the various techniques, a model-supervised Bayesian method for hydrometeor classification, tuned for S- and X-band polarimetric weather radars, can be effectively applied. Once the hydrometeor class is estimated, the retrieval of their water content can also be statistically

  5. An analysis of the data collection modes of a digital weather radar system with respect to significant severe weather features 

    E-print Network

    Neyland, Michael Arthur

    1978-01-01

    LIST OF ACROBYMS EWER CAPPI CAZM DVIP PPI bounded weak echo region constant altitude plan position indi. cator constant altitude reflectivity map digital video integrator and processor plan position indicator. minimum detectable signal PRF... of radar, it was recognized that the device could locate and tracR areas of severe weather and precipitation. Since that time, radar has come to be considered one of the most important tools available to the meteoro- logist for the detection of severe...

  6. Comparison of the Scaling Characteristics of Rainfall Derived from Space-based and Ground-based Radar Observations

    Microsoft Academic Search

    M. Gebremichael; T. M. Over; W. F. Krajewski

    2004-01-01

    The authors compare the scaling characteristics of tropical rainfall derived from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and the S-band ground-based radar (GR). Compared with the PR, the GR has a lower minimum detectable signal (-108 dBm instead of 17 dBZ); a better horizontal resolution (the gate spacing is 250 m, instead of 4.3 km resolution at

  7. ERADERAD 20062006Proceedings ofProceedings of Detecting weather radar clutter

    E-print Network

    of precipitation for every pixel in a Meteosat-8 scene. Via pixel-level image fusion of the radar data from low-level signal processing methods over higher level pattern recognition to data fusion methods results from investigations into detection of weather radar clutter by data fusion with satellite

  8. Monitoring of weather radar receivers using solar signals detected in operational scan data

    E-print Network

    Stoffelen, Ad

    to solar flux units and then compared to observations from the DRAO solar flux monitoring station in Canada- gular biases of the radar antenna using solar signals observed by a scanning weather radar (Huuskonen and data are shown in Figures 1 and 2. III. CONVERSION OF REFLECTIVITY TO SOLAR FLUX A consistent

  9. NEXRAD Weather Radar Observations of the 2006 Augustine Volcanic Eruption Clouds

    Microsoft Academic Search

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

    2006-01-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

  11. Statistical techniques for clutter removal and attenuation detection in weather radar data

    Microsoft Academic Search

    Juan Jose Fernandez-Duran

    1998-01-01

    The presence of clutter and severe attenuation in meteorological radar images are two of the main reasons for the misinterpretation of meteorological radar images and then the errors when using them for weather forecasting. We present a model for clutter removal and a graphical technique for the detection of severe attenuation. The model for clutter removal is a pairwise-interaction Markov

  12. On differentiating ground clutter and insect echoes from Doppler weather radars using archived data

    Microsoft Academic Search

    S. J. Rennie; A. J. Illingworth; S. L. Dance

    2010-01-01

    Normally wind measurements from Doppler radars rely on the presence of rain. During fine weather, insects become a potential radar target for wind measurement. However, it is difficult to separate ground clutter and insect echoes when spectral or polarimetric methods are not available. Archived reflectivity and velocity data from repeated scans provide alternative methods. The probability of detection (POD) method,

  13. Monitoring of weather radar receivers using solar signals detected in operational scan data

    Microsoft Academic Search

    Iwan Holleman; Asko Huuskoneny; Mikko Kurriy; Hans Beekhuis

    When operating a network of weather radars for monitoring of (severe) precipitation and (strong) wind, data quality and network homogeneity are of crucial importance. Using sun for offline calibration of the antenna alignment is a well- established method and tools for this are included in the software packages provided by the radar manufacturers. This offline calibration is typically performed during

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

    Microsoft Academic Search

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

    2011-01-01

    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

  15. Predistortion Arithmetic on Low Sidelobe Pulse Compression Signal for Spaceborne Weather Radar

    Microsoft Academic Search

    Di Zhu; Xiaolong Dong

    2008-01-01

    Pulse compression with very low sidelobes is one of challenges in the design of spaceborne weather radar. To detect the weak echoes of clouds occurring near the strong echoes of sea surface, sidelobe performance below -60 db is needed in the pulse compression system. To achieve such low sidelobes, high SNR and linearity are required in the radar system. But

  16. Quality-based generation of weather radar Cartesian products

    NASA Astrophysics Data System (ADS)

    O?ródka, K.; Szturc, J.

    2014-11-01

    Weather radar data volumes are commonly processed to obtain various 2-D Cartesian products based on the transfer from polar to Cartesian representations through a certain interpolation method. In this research, an algorithm of the spatial interpolation of polar reflectivity data with respect to QI (quality index) data is applied to find the Cartesian reflectivity as PPI (plan position indicator) product and generate a corresponding QI field. On this basis, quality-based versions of standard algorithms for the generation of the following products have been developed: ETOP (echo top), MAX (maximum of reflectivity), and VIL (vertically integrated liquid water). Moreover, as an example of a higher-level product, a CONVECTION (detection of convection) has been defined as a specific combination of the above-listed standard products. A corresponding QI field is determined for each generated product, taking into account the quality of the pixels from which a given product was determined and how large a fraction of the investigated heights was scanned. Examples of such quality-based products are presented in the paper.

  17. Statistical analysis of the impact of radar rainfall uncertainties on water resources modeling

    NASA Astrophysics Data System (ADS)

    He, Xin; Refsgaard, Jens Christian; Sonnenborg, Torben O.; Vejen, Flemming; Jensen, Karsten H.

    2011-09-01

    Uncertainty analysis in hydrological modeling has become an essential step in the scientific interpretation of model results and a useful tool to support decision making. Among many uncertainty sources in the modeling practice, uncertainties in precipitation estimation play an important role since it is the main driving force for other hydrological processes. The present study demonstrates a statistical method for generating radar rainfall realizations that account for the uncertainties in radar-based quantitative precipitation estimation (QPE). The random sampling technique used to generate stochastic uncertainty fields is based on sequential Gaussian simulation. The hydrological impact of the uncertainties in radar QPE is analyzed by propagating the rainfall ensemble through a distributed and integrated water resources model. The study shows that the uncertainty of the simulated stream discharge depends on the intensity of the rainfall input signal. The coefficient of variation is calculated for simulated stream discharge and groundwater recharge at subcatchments with various sizes. The results reveal strong scale dependency showing higher variations of hydrological uncertainties at smaller catchments, especially for catchment areas smaller than 50 km2. The uncertainties from precipitation input are generally amplified in the hydrological model. This effect is less obvious for groundwater recharge but rather substantial for stream discharge, where the coefficient of variation increases by a factor of three.

  18. Improved accuracy of radar WPMM estimated rainfall upon application of objective classification criteria

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Daniel; Amitai, Eyal; Wolff, David B.

    1995-01-01

    Application of the window probability matching method to radar and rain gauge data that have been objectively classified into different rain types resulted in distinctly different Z(sub e)-R relationships for the various classifications. These classification parameters, in addition to the range from the radar, are (a) the horizontal radial reflectivity gradients (dB/km); (b) the cloud depth, as scaled by the effective efficiency; (c) the brightband fraction within the radar field window; and (d) the height of the freezing level. Combining physical parameters to identify the type of precipitation and statistical relations most appropriate to the precipitation types results in considerable improvement of both point and areal rainfall measurements. A limiting factor in the assessment of the improved accuracy is the inherent variance between the true rain intensity at the radar measured volume and the rain intensity at the mouth of the rain guage. Therefore, a very dense rain gauge network is required to validate most of the suggested realized improvement. A rather small sample size is required to achieve a stable Z(sub e)-R relationship (standard deviation of 15% of R for a given Z(sub e)) -- about 200 mm of rainfall accumulated in all guages combined for each classification.

  19. Improved Range Profiling Algorithms Of Rainfall Rate From A Spaceborne Radar With Path-integrated Attenuation Constraint

    Microsoft Academic Search

    M. Marzoug; P. Amayenc

    1990-01-01

    A new range profiling algorithm for rainfall rate retrieval from a downward looking spaceborne one frequency radar is presented. It is based upon a linear reformulation of the radar equation.The path integrated attenuation given by the surface echo measurement is used as a constraint for normalizing the range gated rain echoes. The expected performances are studied analytically and compared with

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

    E-print Network

    Cho, John Y. N.

    Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part I: Clutter Filtering JOHN (Cho et al. 2003). Multi-PRI signals can be processed to effectively sepa- rate different-trip weather Multiple pulse repetition interval (multi-PRI) transmission is part of an adaptive signal transmission

  1. Techniques for detecting and tracking airplanes using weather radar WSR-88D

    Microsoft Academic Search

    Svetlana Bachmann; Victor DeBrunner; Dusan Zrnic; Mark Yeary

    2004-01-01

    For the first time, weather radar echoes from point scatterers (airplanes) in a non-stormy environment are investigated in the time and frequency domains and compared to model simulations to build a background for differentiating these echoes from weather signals and to develop procedures for data censoring.

  2. Space-time variation of the Typhoon Morkat (2009) rainband structure over Taiwan's complex terrain observed by weather radars and rain gauge measurements

    NASA Astrophysics Data System (ADS)

    Liou, Yu-Chieng; Wang, Tai-Chi Chen; Tsai, Yi-Chun; Tang, Yu-Shuang

    2013-04-01

    This research studies the structure of precipitation systems over Taiwan as Typhoon Morakot (2009) impinged on the island on 8 August 2009 using data observed by weather radars and rain gauges. A newly-designed multiple-Doppler radar synthesis technique particularly designed for dealing with non-flat surfaces is applied to analyze the three-dimensional wind fields over the ocean and terrain. In the northern and southern portion of the analysis domain where the mountain slope is relatively gentle and steep, respectively, the radar reflectivity measurements indicate that the precipitation systems exhibit horizontal translation in the north and abrupt intensification in the south. Far from the southern mountainous region, a north-south oscillation of an east-west-oriented band of strong radar reflectivity (>40 dBZ) with a horizontal span of 20 km is observed. Along the mountain slopes, the region of strong radar reflectivity expands to a much wider north-south-oriented area. The major precipitation is confined to the windward side of the mountains. Further analysis reveals that the upstream atmosphere is statically unstable, which implies that the lifting of the incoming convective cells by the topography will easily trigger precipitation. Thus, most of the moisture will be consumed before the air reaches the leeward side of the mountains. The long duration and the wide range of heavy precipitation in the mountainous regions resulted in a record-breaking rainfall amount of 2,000 mm over four days. A noticeable feature of the prevailing westerly flow is a wind speed maximum (~ 40 m s-1) above the mountain crest, which can be explained by a simplified shallow water model. The capability of applying the weather radar to provide a reliable quantitative estimate of the rainfall over a large area with high temporal and spatial resolution is shown using dual-polarimetric radar data. Our results demonstrate the potential applications of the knowledge of the wind and precipitation characteristics in hydrology and other related fields.

  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.

    2003-01-01

    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. Our analysis of discrepancies between the PR rainfall and attenuation suggests that uncertainty in the assumed drop size distribution and associated attenuation/reflectivity/rainfall relationships inherent in single-frequency radar methods is a serious issue for studies of interannual variability.

  4. 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 gauge networks. Due to the relatively long range and lower spatial and temporal resolution the C-band images contained less information than X-band scans of the same hydrometeors. On the other hand, per event statistics indicate that the majority of variance in rain gauge measurements can be explained from the co-located X-band radar pixel. Quantitative retrieval of accumulation was possible out to about 15km range after applying range and bias correction.

  5. Automatic suppression of anomalous propagation clutter for noncoherent weather radars

    Microsoft Academic Search

    H. R. A. Wessels; J. H. Beekhuis

    1992-01-01

    Pulse to pulse radar echo fluctuations were used to distinguish rain from anomalous propagation clutter. For one deg sectors at a fixed range 14 echo samples from successive pulses are tested for clutter. This test has a clutter detection rate of only 45 percent, but in each 1 deg\\/km polar radar pixel 8 range bins can be tested. The 8

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

    Microsoft Academic Search

    K. Lai; D. Longstaff; G. Callaghan

    2001-01-01

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

  7. Model-oriented hydrometeor classification and water content estimate using dual-polarized weather radars

    Microsoft Academic Search

    F. S. Marzano; D. Scaranari; M. Montopoli; G. Vulpiani

    2008-01-01

    Dual-polarized weather radars are capable to detect and identify different classes of hydrometeors, within stratiform and convective storms exploiting polarimetric diversity. A model-supervised Bayesian method for hydrometeor classification (BRAHC), tuned for S- and X- band, is described in this study. The critical issue of X-band radar data processing is the path attenuation correction, usually negligible at S-band. During the IHOP

  8. 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.

  9. Distributed Weather Radar Using X-Band Active Arrays

    Microsoft Academic Search

    D. J. McLaughlin; E. A. Knapp; Y. Wang; V. Chandrasekar

    2007-01-01

    Dense networks of short-range radars capable of mapping storms and detecting atmospheric and airborne hazards are described. Comprised of physically small, low-power antennas, these networks defeat the earth curvature blockage that limits today's long-range radar networks and enable high resolution views that extend from the lower-troposphere up to the tops of storms. The networks are comprised of 1-meter antennas that

  10. Distributed weather radar using X-band active arrays

    Microsoft Academic Search

    David J. McLaughlin; Eric A. Knapp; Y. Wang; V. Chandrasekar

    2009-01-01

    Dense networks of short-range radars capable of mapping storms and detecting atmospheric and airborne hazards are described. Comprised of physically small, low-power antennas, these networks defeat the Earth curvature blockage that limits today's long-range radar networks and enable high resolution views that extend from the lower-troposphere to the tops of storms. The networks are comprised of 1-meter antennas that transmit

  11. New algorithm for integration between wireless microwave sensor network and radar for improved rainfall measurement and mapping

    NASA Astrophysics Data System (ADS)

    Liberman, Y.; Samuels, R.; Alpert, P.; Messer, H.

    2014-05-01

    One of the main challenges for meteorological and hydrological modelling is accurate rainfall measurement and mapping across time and space. To date the most effective methods for large scale rainfall estimates are radar, satellites, and more recently, received signal level (RSL) measurements received from commercial microwave networks (CMN). While these methods provide improved spatial resolution over traditional rain gauges, these have their limitations as well. For example, the wireless CMN, which are comprised of microwave links (ML), are dependant upon existing infrastructure, and the ML arbitrary distribution in space. Radar, on the other hand, is known in its limitation in accurately estimating rainfall in urban regions, clutter areas and distant locations. In this paper the pros and cons of the radar and ML methods are considered in order to develop a new algorithm for improving rain fall measurement and mapping, which is based on data fusion of the different sources. The integration is based on an optimal weighted average of the two data sets, taking into account location, number of links, rainfall intensity and time step. Our results indicate that by using the proposed new method we not only generate a more accurate 2-D rainfall reconstructions, compared with actual rain intensities in space, but also the reconstructed maps are extended to the maximum coverage area. By inspecting three significant rain events, we show an improvement of rain rate estimation over CMN or radar alone, almost uniformly, both for instantaneous spatial measurements, as well as in calculating total accumulated rainfall. These new improved 2-D rainfall maps, and the accurate rainfall measurements over large areas at sub-hourly time scales, will allow for improved understanding, initialization and calibration of hydrological and meteorological models necessary, mainly, for water resource management and planning.

  12. Improved range-profiling algorithm of rainfall rate from a spaceborne radar with path-integrated attenuation constraint

    Microsoft Academic Search

    Mongi Marzoug; Paul Amayenc

    1991-01-01

    A range-profiling algorithm for rainfall rate retrieval from a single-frequency downward-looking spaceborne radar is presented. The algorithm is based on a linear reformulation of the radar equation. The path-integrated attenuation given by the surface echo measurement is used as a constraint for normalizing the range-gated rain echoes. The expected performances are studied analytically and compared with those of the approach

  13. Rainfall and Snowfall Observations by the Airborne Dual-frequency Precipitation Radar during the Wakasa Bay Experiment

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Im, Eastwood; Durden, Stephen L.; Meagher, Jonathan P.

    2004-01-01

    Radar data obtained through the NASA/JPL Airborne Precipitation Radar APR-2 during the Wakasa Bay Experiment in January/February 2003 were processed to obtain calibrated reflectivity measurements, rainfall/snowfall velocity measurements, classification of the surface type and detection of the boundaries of the melting layer of precipitation. In this paper the processing approach is described together with an overview of the resulting data quality and known issues.

  14. 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 developed for 6X (6 events per year), 4X, 3X, 2X, 1, 2, 5 and 10 year recurrence, and durations from 5 minutes to 7-days. A comparison is made between DARF derived in these analyses with NOAA Atlas 12 DARF, the USACE Sierra Madre Storm and other DARF developed for the interior Southwest. Orographic increases in DDF are related to the Los Angeles County Flood Control District Hydrology Manual 24-hr 50-yr Precipitation maps, elevation from USGS topographic maps and Mean Annual Precipitation maps.

  15. 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 ultimate goal. The Precipitation Radar (PR) aboard the TRMM satellite is the first ever spaceborne radar dedicated to three-dimensional, global precipitation measurements over the tropics and the subtropics, as well as the detailed synopsis of a wide range of tropical rain storm systems. In only twelve months since launch, the PR, together with other science instruments abroad the satellite have already provided unprecedented insights into the rainfall systems. It is anticipated the a lot more exciting and important rain observations would be made by TRMM throughout its mission duration. While TRMM has provided invaluable data to the user community, it is only the first step towards advancing our knowledge on rain processes and its contributions to climate variability. It is envisioned that a TRMM follow-on mission is needed in such a way to capitalize on the pioneering information provided by TRMM, and its instrument capability must be extended beyond TRMM in such a way to fully address the key science questions from microphysical to climatic time scale. In fact, a number of new and innovative mission concepts have recently put forth for this purpose. Almost all of these new concepts have suggested the utility of a more advanced, high-resolution, Doppler-enabled, vertical profiling radar that can provide multi-parameter observations of precipitation. In this paper, a system concept for a second- gene ration precipitation radar (PR-2) which addresses the above requirements will be described.

  16. 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.

  17. The use of composite radar photographs in synoptic weather analysis

    E-print Network

    Smith, G. D.

    1957-01-01

    Radar Nstcorology Section of the A. and H. College of Teens. orientation, velocity er wanner of tarnation. ~S uall line. hn extended line of convective showers or thunder- sterna which is definitely associated with a surface or upper cold front... lines i'rom pressure anal- ysis. Two of rho Nnsu which occurred during chs storms of 26 Hsy end 6 June did influesoo cho prcssure pattern, but not until they hed been in ~stance for several bours. Gracious plotcad on radar com- posito for Q93IK 26...

  18. Maximum-Likelihood Spectral Estimation and Adaptive Filtering Techniques with Application to Airborne Doppler Weather Radar

    Microsoft Academic Search

    Yingcho Lai

    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

  19. Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar

    Microsoft Academic Search

    Jonathan Y. Lai

    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

  20. The Feasibility of Data Whitening to Improve Performance of Weather Radar

    Microsoft Academic Search

    A. C. Koivunen; A. B. Kostinski

    1999-01-01

    The problem of efficient processing of correlated weather radar echoes off precipitation is considered. An approach based on signal whitening was recently proposed that has the potential to significantly improve power estimation at a fixed pulse repetition rate\\/scan rate, or to allow higher scan rates at a given level of accuracy. However, the previous work has been mostly theoretical and

  1. Alteration and performance evaluation of a GCF for staggered PRT weather radar data

    Microsoft Academic Search

    Svetlana Bachmann; Sebastian Torres; Dusan Zrnic

    2008-01-01

    In Doppler weather radar data acquisition, pulse repetition time (PRT) dictates the maximum unambiguous range (ra) and the maximum unambiguous velocity (va). The choice of PRT creates a trade-off; large range coverage can be realized at a cost of small Doppler velocities and large Doppler velocities can be detected at a cost of short range coverage. A data acquisition scheme

  2. Model-Based Weather Radar Remote Sensing of Explosive Volcanic Ash Eruption

    Microsoft Academic Search

    Frank Silvio Marzano; Sara Marchiotto; Christiane Textor; David J. Schneider

    2010-01-01

    Microphysical and dynamical features of volcanic ash clouds can be quantitatively monitored by using ground-based microwave weather radars. These systems can provide data for determining the ash volume, total mass, and height of eruption clouds. In order to demonstrate the unique potential of this microwave active remote-sensing technique, the case study of the eruption of Augustine Volcano in Alaska in

  3. Pulse Compression with Very Low Sidelobes in a Spaceborne Weather Radar

    Microsoft Academic Search

    Di Zhu; Xiaolong Dong; Wenming Lin

    2008-01-01

    Pulse compression with very low sidelobes is one of challenges in the design of spaceborne weather radar. To detect the weak echoes of clouds occurring near the strong echoes of sea surface, sidelobe performance below -60 db is needed in the pulse compression system. Based on the traditional ways of pulse compression, double Kaiser Windows are applied here for sidelobe

  4. Estimation of Specific Differential Phase and Differential Backscatter Phase From Polarimetric Weather Radar Measurements of Rain

    Microsoft Academic Search

    Tobias Otto; Herman W. J. Russchenberg

    2011-01-01

    The estimation of the specific differential phase par- ticularly in the presence of the differential backscatter phase and nonuniform propagation paths is a long-standing goal in weather radar polarimetry. Furthermore, a reliable estimator of the differential backscatter phase for precipitation measure- ments has not been proposed yet, although it contains valuable information about the presence of non-Rayleigh scattering and the

  5. An Examination of Version 5 Rainfall Estimates from the TRMM Microwave Imager, Precipitation Radar, and Rain Gauges on Global, Regional, and Storm Scales

    E-print Network

    Rutledge, Steven

    microwave and spaceborne radar sensors. However, sources of error in these estimates often stem fromAn Examination of Version 5 Rainfall Estimates from the TRMM Microwave Imager, Precipitation Radar Current affiliation: Radar Meteorology Group, Department of Atmospheric Science, Colorado State University

  6. Better Weather Prediction and Climate Diagnostics Using Rainfall Measurements from Space

    NASA Technical Reports Server (NTRS)

    Hou, Arthur; Zhang, Sara; Li, Jui-Lin; Reale, Oreste

    2002-01-01

    Progress in understanding of the role of water in global weather and climate is currently limited by our knowledge of the spatial and temporal variability of primary hydrological fields such as precipitation and evaporation. The Tropical Rainfall Measuring Mission (TRMM) has recently demonstrated that use of microwave-based rainfall observations from space in data assimilation can provide better climate data sets and improve short-range weather forecasting. At NASA, we have been exploring non-traditional approaches to assimilating TRMM Microwave Imager (TMI) and Special Sensor Microwavehager (SSM/I) surface rain rate and latent heating profile information in global systems. In this talk we show that assimilating microwave rain rates using a continuous variational assimilation scheme based on moisture tendency corrections improves quantitative precipitation estimates (QPE) and related clouds, radiation energy fluxes, and large-scale circulations in the Goddard Earth Observing System (GEOS) reanalyses. Short-range forecasts initialized with these improved analyses also yield better QPE scores and storm track predictions for Hurricanes Bonnie and Floyd. We present a status report on current efforts to assimilate convective and stratiform latent heating profile information within the general variational framework of model parameter estimation to seek further improvements. Within the next 5 years, there will be a gradual increase in microwave rain products available from operational and research satellites, culminating to a target constellation of 9 satellites to provide global rain measurements every 3 hours with the proposed Global Precipitation Measurement (GPM) mission in 2007/2008. Based on what has been learned from TRMM, there is a high degree of confidence that these observations can play a'major role in improving weather forecasts and producing better global datasets for understanding the Earth's water and energy cycle. The key to success is to adopt an integrated approach to retrieval, validation, modeling, and data assimilation in a coordinated end-to-end observation-application program.

  7. A coupled stochastic spacetime intermittent random cascade model for rainfall downscaling

    E-print Network

    Ramírez, Jorge A.

    A coupled stochastic spacetime intermittent random cascade model for rainfall downscaling Boosik; published 21 October 2010. [1] Analysis of Next Generation Weather Radar rainfall data indicates that for the central United States, rainfall exhibits a composite behavior with respect to its spatial and temporal

  8. 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 application of time-lapse borehole radar for characterizing rainfall infiltration.

  9. Passive Microwave Rainfall Error Analysis using High-Resolution X-band Dual-Polarization Radar Observations in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Derin, Yagmur; Anagnostou, Emmanouil; Kalogiros, John; Anagnostou, Marios

    2015-04-01

    Accuracy and reliability of hydrological modeling studies heavily depends on quality and availability of precipitation estimates. Difficulties in representation of high rainfall variability over mountainous areas using ground based sensors make satellite remote sensing techniques attractive for hydrologic studies over these regions. Even though satellite-based rainfall measurements are quasi global and available at high spatial resolution, these products have uncertainties that necessitate use of error characterization and correction procedures based upon more accurate in situ rainfall measurements, such as those obtained during experimental studies with research radars. This study evaluates rainfall estimates from passive microwave (PMW) sensors onboard different earth orbiting platforms based on high spatial (150 m) and temporal (3 min) resolution rainfall estimates derived from dual-polarization X-band radar (XPOL) observations during various field experiments in US and the Mediterranean region. The study first conducts independent error analysis of the XPOL precipitation estimates using independent in situ observations from rain gauges and disdrometers. Subsequently, coincident XPOL and PMW rainfall estimates are matched in space and time for a number of convective and stratiform type precipitation events. Standard GPROF PMW retrievals on SSM/I, TMI (2A12) and GPM-DPR observations are used to conduct the error analysis. All coincident XPOL data are extracted for the indicated overpasses to produce the satellite field-of-view averages for the orbital PMW sensor and produce match-ups of PMW/XPOL rainfall and raindrop size distribution parameters. In addition, gridded merged PMW datasets (MWCOMB, 3B40RT) that are used in most merged rainfall products are evaluated against the XPOL measurements. We will present error analysis results of PMW rainfall estimation and investigate dependences on precipitation type, vertical structure and precipitation microphysics (derived from XPOL).

  10. Relationship Among High Rainfall Rates, Atmospheric Moisture, and Temperature Based on High-Resolution Radar-Based Precipitation Estimates

    NASA Astrophysics Data System (ADS)

    Stevens, S. E.; Nelson, B. R.; Kunkel, K.; Prat, O. P.; Karl, T. R.

    2014-12-01

    Global warming is expected to increase maximum rainfall rates in many areas. A primary factor for this expectation is the large increase in atmospheric water vapor content expected with global warming, a simple application of the Clausius-Clapeyron (C-C) relationship. However, the spatial variations of changes will also be modulated by changes in frequency, intensity and location of the storms that produce heavy rainfall. In this study, we explore one dimension of this complex issue, specifically the observational evidence for robust relationships among atmospheric temperature, total precipitable water, and the most extreme magnitudes of surface rainfall rates. We investigate the extent to which a C-C relationship is followed and whether this is dependent on rainstorm duration. This information is crucial to understanding how to incorporate climate change considerations into extreme rainfall design values. Using high-frequency rainfall measurements from both in-situ networks such as the US Climate Reference Network (USCRN) and radar estimates such as the newly-developed National Mosaic and Multisensor Quantitative Precipitation Estimate (NMQ/Q2), rainfall rates and accumulations are compared to precipitable water estimates obtained from both radiosonde data and hourly gridded model analysis. A variety of durations are explored to determine if rising temperature, and thus rising precipitable water availability, corresponds to an increase in the most extreme values of short-term rainfall intensity, longer-term rainfall accumulation, both, or neither.

  11. 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.

  12. Flash Flood Modeling in Changing Hydrological Conditions Using a Hydrological Model and Radar Rainfall Data

    NASA Astrophysics Data System (ADS)

    Rozalis, S.; Price, C.; Yair, Y.; Morin, E.

    2009-04-01

    Flash floods are one of the most devastating natural disasters, causing much damage to property and can often lead to loss of human lives. This is a particular problem in the Mediterranean region. Understanding the meteorological and hydrological conditions for flash flood generation is an essential step on the way to forecast them and prevent some of the damage they might cause. The occurrence of a flood event is determined by meteorological conditions, producing large amounts of precipitation over a short period of time, as well as hydrological conditions, such as soil type, land cover and soil antecedent moisture conditions, which vary throughout the year and from place to place. The current study is a part of the FLASH research project (EU-FP6). In this work we use a hydrological model with data from twenty major flood events which occurred in the study area between 1991 and 2006, to better understand the role of changing hydrological and meteorological conditions in generating flash floods and in order to improve the prediction of future flash flood events. The model's runoff calculation is done by the Soil Conservation Service Curve Number method, taking into account antecedent soil moisture, land use and soil type. Runoff flow over hillslopes and channels is calculated by the Kinematic wave method. No calibration with measured flow data was performed. As rainfall data we use radar rainfall estimations adjusted to rain gauge along the basin. The model is applied over a 27 km2 basin located in a Mediterranean area in North-Eastern Israel with mean annual precipitation of about 450 mm. The main land use in this area is agriculture, with forests and orchards on the upper part and cultivated fields on its lower parts. We compare the model's runoff calculations with flow observations derived from a flow gauge located on the catchment outlet. The model allows us to explore the special synoptic, rainfall and surface conditions, responsible for the generation of these floods.

  13. Performance of high-resolution X-band weather radar networks - the PATTERN example

    NASA Astrophysics Data System (ADS)

    Lengfeld, K.; Clemens, M.; Münster, H.; Ament, F.

    2014-12-01

    This publication intends to prove that a network of low-cost local area weather radars (LAWR) is a reliable and scientifically valuable complement to nationwide radar networks. A network of four LAWRs has been installed in northern Germany within the framework of the Precipitation and Attenuation Estimates from a High-Resolution Weather Radar Network (PATTERN) project observing precipitation with a temporal resolution of 30 s, a range resolution of 60 m and a sampling resolution of 1° in the azimuthal direction. The network covers an area of 60 km × 80 km. In this paper, algorithms used to obtain undisturbed precipitation fields from raw reflectivity data are described, and their performance is analysed. In order to correct operationally for background noise in reflectivity measurements, noise level estimates from the measured reflectivity field are combined with noise levels from the last 10 time steps. For detection of non-meteorological echoes, two different kinds of clutter algorithms are applied: single-radar algorithms and network-based algorithms. Besides well-established algorithms based on the texture of the logarithmic reflectivity field (TDBZ) or sign changes in the reflectivity gradient (SPIN), the advantage of the unique features of the high temporal and spatial resolution of the network is used for clutter detection. Overall, the network-based clutter algorithm works best with a detection rate of up to 70%, followed by the classic TDBZ filter using the texture of the logarithmic reflectivity field. A comparison of a reflectivity field from the PATTERN network with the product from a C-band radar operated by the German Meteorological Service indicates high spatial accordance of both systems in the geographical position of the rain event as well as reflectivity maxima. Long-term statistics from May to September 2013 prove very good accordance of the X-band radar of the network with C-band radar, but, especially at the border of precipitation events, higher-resolved X-band radar measurements provide more detailed information on precipitation structure because the 1 km range gate of C-band radars is only partially covered with rain. The standard deviation within a range gate of the C-band radar with a range resolution of 1 km is up to 3 dBZ at the borders of rain events. The probability of detection is at least 90%, the false alarm ratio less than 10% for both systems. Therefore, a network of high-resolution low-cost LAWRs can give valuable information on the small-scale structure of rain events in areas of special interest, e.g. urban regions, in addition to the nationwide radar networks.

  14. 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.

  15. 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 Retrieval (VARR) algorithm for single-polarization and double-polarization systems, shown in previous work, has been applied to C-band and X-band weather radar data. In this work we show radar based estimations of eruptive source parameters for Holuhraun events in the fall of 2014. This extremely gas-rich eruption was characterized by sustained lava fountaining in the first months. At the same time some ash-rich episodes were reported from the field together with minor tephra fallout occurring close to the eruption site. Since the beginning of the eruption, the Icelandic Meteorological Office (IMO) monitored the volcanic plume using two ground-based radars: a C-band weather radar (5.5 GHz) in Egilsstaðir and an X-band polarimetric mobile radar (9.4 GHz) located at Vaðalda, about 20 km away from the eruption site. The VARR algorithm has been applied to few specific events and the radar products, such as top plume height, concentration, ash load and mass flow rate, derived from the two radars, are here discussed in terms of retrievals and inter-comparisons with available in-situ information. Both radar-based estimations show a presence of volcanic particles in the observed plume. Also, airborne fine ash particles are identified at low levels of plume probably due to a wind-induced re-suspension of dust and ancient volcanic ash deposited in the area around Holuhraun.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  17. 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 extension of the 3D composite to all of Germany is therefore possible and set as a goal.

  18. Statistical modelling of rainfall-induced shallow landsliding using static predictors and numerical weather predictions: preliminary results

    NASA Astrophysics Data System (ADS)

    Capecchi, V.; Perna, M.; Crisci, A.

    2015-01-01

    Our study is aimed at estimating the added value provided by Numerical Weather Prediction (NWP) data for the modelling and prediction of rainfall-induced shallow landslides. We implemented a quantitative indirect statistical modelling of such phenomena by using, as input predictors, both geomorphological, geological, climatological information and numerical data obtained by running a limited-area weather model. Two standard statistical techniques are used to combine the predictor variables: a generalized linear model and Breiman's random forests. We tested these models for two rainfall events that occurred in 2011 and 2013 in Tuscany region (central Italy). Modelling results are compared with field data and the forecasting skill is evaluated by mean of sensitivity-specificity receiver operating characteristic (ROC) analysis. In the 2011 rainfall event, the random forests technique performs slightly better than generalized linear model with area under the ROC curve (AUC) values around 0.91 vs. 0.84. In the 2013 rainfall event, both models provide AUC values around 0.7. Using the variable importance output provided by the random forests algorithm, we assess the added value carried by numerical weather forecast. The main results are as follows: (i) for the rainfall event that occurred in 2011 most of the NWP data, and in particular hourly rainfall intensities, are classified as "important" and (ii) for the rainfall event that occurred in 2013 only NWP soil moisture data in the first centimetres below ground is found to be relevant for landslide assessment. In the discussions we argue how these results are connected to the type of precipitation observed in the two events.

  19. 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

    2015-01-01

    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

  20. 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

  1. Rain-Cell Identification and Modeling for Propagation Studies from Weather Radar Images

    Microsoft Academic Search

    V. Pestoriza; A. Nu?ñez; P. Mariño; F. P. Fonta?n; U.-C. Fiebig

    2010-01-01

    This study aims to characterize and model the rain fields for propagation studies from weather radar images of the northwest coast of Spain. The study includes the modeling of these images according to two well-known rain-cell models, EXCELL and HYCELL. For this analysis, a procedure for detecting rain field-s and an algorithm for identifying rain cells within the images is

  2. Spatio-temporal analyses of correlation between NOAA satellite RFE and weather stations' rainfall record in Ethiopia

    NASA Astrophysics Data System (ADS)

    Beyene, Ephrem Gebremariam; Meissner, Bernd

    The study analysed monthly satellite RFE (rainfall estimates) from NOAA (National Atmospheric and Oceanic Administration) and monthly rainfall records (January 1996-December 2006) collected from weather stations by NMA (National Meteorological Agency of Ethiopia). Can the RFE data be used reliably to analyse seasonal rainfall variability? After doing spatio-temporal analyses of the two datasets, a significant correlation during the important rainy seasons, summer and spring and a low correlation during winter was shown. In conclusion the RFE images can be used reliably for early warning systems in the country and to empower decision makers on the consequences caused by the changes in the magnitude, timing, duration, and frequency of rainfall deficits on different spatial and temporal scales.

  3. A STATUS REPORT ON THE RF AND DIGITAL COMPONENTS OF THE MULTICHANNEL RECEIVER DEVELOPMENT AT THE NATIONAL WEATHER RADAR TESTBED

    Microsoft Academic Search

    M. Yeary; J. Crain; A. Zahrai; R. Kelley; J. Meier; Y. Zhang; I. Ivic; C. Curtis; R. Palmer; T.-Y. Yu; G. Zhang; R. Doviak; P. Chilson; M. Xue; Q. Xu

    This paper describes the status of a project that will simultaneously digitize the radar signals coming from eight channels on the phased array antenna at the Na- tional Weather Radar Testbed (NWRT) in Norman, Ok- lahoma. At the current time, a single-channel digital receiver is operational on this S-band radar to mimic the current WSR-88D capability. The multi-channel dig- ital

  4. Performance of high-resolution X-band weather radar networks - the PATTERN example

    NASA Astrophysics Data System (ADS)

    Lengfeld, K.; Clemens, M.; Münster, H.; Ament, F.

    2014-08-01

    This publication intends to proof that a network of low-cost local area weather radars (LAWR) is a reliable and scientifically valuable complement to nationwide radar networks. A network of four LAWRs has been installed in northern Germany within the framework of the project Precipitation and Attenuation Estimates from a High-Resolution Weather Radar Network (PATTERN) observing precipitation with temporal resolution of 30 s, azimuthal resolution of 1° and spatial resolution of 60 m. The network covers an area of 60 km × 80 km. In this paper algorithms used to obtain undisturbed precipitation fields from raw reflectivity data are described and their performance is analysed. In order to correct for background noise in reflectivity measurements operationally, noise level estimates from the measured reflectivity field is combined with noise levels from the last 10 time steps. For detection of non-meteorological echoes two different kinds of clutter filters are applied: single radar algorithms and network based algorithms that take advantage of the unique features of high temporal and spatial resolution of the network. Overall the network based clutter filter works best with a detection rate of up to 70%, followed by the classic TDBZ filter using the texture of the logarithmic reflectivity field. A comparison of a reflectivity field from the PATTERN network with the product from a C-band radar operated by the German Meteorological Service indicates high spatial accordance of both systems in geographical position of the rain event as well as reflectivity maxima. A longterm study derives good accordance of X-band radar of the network with C-band radar. But especially at the border of precipitation events the standard deviation within a range gate of the C-band radar with range resolution of 1 km is up to 3 dBZ. Therefore, a network of high-resolution low-cost LAWRs can give valuable information on the small scale structure of rain events in areas of special interest, e.g. urban regions, in addition the nationwide radar networks.

  5. Application of Radar-Rainfall Estimates to Probable Maximum Precipitation in the Carolinas

    NASA Astrophysics Data System (ADS)

    England, J. F.; Caldwell, R. J.; Sankovich, V.

    2011-12-01

    Extreme storm rainfall data are essential in the assessment of potential impacts on design precipitation amounts, which are used in flood design criteria for dams and nuclear power plants. Probable Maximum Precipitation (PMP) from National Weather Service Hydrometeorological Report 51 (HMR51) is currently used for design rainfall estimates in the eastern U.S. The extreme storm database associated with the report has not been updated since the early 1970s. In the past several decades, several extreme precipitation events have occurred that have the potential to alter the PMP values, particularly across the Southeast United States (e.g., Hurricane Floyd 1999). Unfortunately, these and other large precipitation-producing storms have not been analyzed with the detail required for application in design studies. This study focuses on warm-season tropical cyclones (TCs) in the Carolinas, as these systems are the critical maximum rainfall mechanisms in the region. The goal is to discern if recent tropical events may have reached or exceeded current PMP values. We have analyzed 10 storms using modern datasets and methodologies that provide enhanced spatial and temporal resolution relative to point measurements used in past studies. Specifically, hourly multisensor precipitation reanalysis (MPR) data are used to estimate storm total precipitation accumulations at various durations throughout each storm event. The accumulated grids serve as input to depth-area-duration calculations. Individual storms are then maximized using back-trajectories to determine source regions for moisture. The development of open source software has made this process time and resource efficient. Based on the current methodology, two of the ten storms analyzed have the potential to challenge HMR51 PMP values. Maximized depth-area curves for Hurricane Floyd indicate exceedance at 24- and 72-hour durations for large area sizes, while Hurricane Fran (1996) appears to exceed PMP at large area sizes for short-duration, 6-hour storms. Utilizing new methods and data, however, requires careful consideration of the potential limitations and caveats associated with the analysis and further evaluation of the newer storms within the context of historical storms from HMR51. Here, we provide a brief background on extreme rainfall in the Carolinas, along with an overview of the methods employed for converting MPR to depth-area relationships. Discussion of the issues and limitations, evaluation of the various techniques, and comparison to HMR51 storms and PMP values are also presented.

  6. 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.

  7. Overview of the Greater Lyon weather radar advances from 90's to 2008

    NASA Astrophysics Data System (ADS)

    Renard, F.; Comby, J.

    2010-03-01

    The local weather radar of Lyon, part of the Aramis network of Meteo-France, is currently located 40 km from the urban community. The measurement quality of this tool is subjected to constant improvements from Meteo-France. Indeed, its hydrological measurement quality has steadily evolved from the early 90's until today. This article, therefore, proposes a return on these innovations, assessing measurement quality over the territory of Greater Lyon. This study is based on two successive radar locations, and also on raw reflectivity data and on rain accumulation over the past 15 min (Hydram) or 5 min (Panthere). The measurement performed on the site Satolas was unsatisfactory because of too many ground clutters; and therefore the radar was moved to Saint-Nizier. This new location associated with radar Hydram rain accumulation has reduced the problem of ground clutters. These rain accumulation data have given correct results in comparison with local data of the raingauge network of Greater Lyon, after a global and spatially uniform correction, based on these gauges. The latest generation of radar rain accumulation (Panthere) has, nearly completely, eliminated the problem of ground clutter in the urban area and provides very satisfactory measurements, especially during intense rain events.

  8. Robust estimation of mean Doppler frequency for the measurement of average wind velocity in a weather radar

    Microsoft Academic Search

    Jonggil Lee

    1994-01-01

    In a Doppler weather radar, high resolution windspeed profile measurements are needed to provide reliable detection of a hazardous weather condition. For this purpose, the pulse pair method is generally considered to be the most efficient estimator. However, this estimator has some bias errors due to nonsymmetric spectra and may yield meaningless results in the case of a multimodal return

  9. Adaptive Technique for Clutter and Noise Supression in Weather Radar Exposes Weak Echoes Over an Urban Area

    Microsoft Academic Search

    Svetlana Bachmann; Victor DeBrunner; Dusan Zrnic; Mark Yeary

    2007-01-01

    We present an adaptive spectral technique for ground clutter and noise suppression in weather radar echoes. This technique is especially good for detecting weak echoes that are either submerged in noise or masked by the residuals from ground clutter if standard techniques for clutter suppression are used. Our technique is demonstrated on two clear air cases observed with Doppler weather

  10. Weather

    NSDL National Science Digital Library

    Ms. LAi

    2007-02-08

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

  11. The error structure of radar rainfall accumulations Sandy Dance and Alan Seed

    E-print Network

    Dance, Sandy

    2011-01-09 00:30:00 Error (radar - gauge): mean -0.08135 standard deviation 1.43064 mm/30min) shows the same but for the whole of January. It appears the radar and gauge are a close match radar (not shown) also has a good match between radar and gauge, but not as good as Mt Stapylton

  12. 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 integrates a two-dimensional grid (MIKE 21) and a one-dimensional channel flow simulation tool (MIKE 11). The model was successfully calibrated and validated using water level and salinity data collected at monitoring stations in the channels and throughout the marsh areas. The model prediction agreed favorably with the field measurements at the daily and monthly average scale. Uncertainties in the bathymetric data, open water boundary, as well as the operation schedules of water control structures prevented the model from being validated at a higher temporal frequency. Ongoing monitoring efforts are being used to minimize these uncertainties.

  13. Structure of precipitating systems over Taiwan’s complex terrain during Typhoon Morakot (2009) as revealed by weather radar and rain gauge observations

    NASA Astrophysics Data System (ADS)

    Liou, Yu-Chieng; Wang, Tai-Chi Chen; Tsai, Yi-Chun; Tang, Yu-Shuang; Lin, Pay-Liam; Lee, Yung-An

    2013-12-01

    This study documents from an observational perspective the structure of precipitation systems over the complex topography of Taiwan as Typhoon Morakot (2009) impinged on the island on 8 August 2009. An advanced multiple-Doppler radar synthesis technique particularly designed for dealing with non-flat surfaces is applied to analyze the three-dimensional wind fields over the ocean and terrain. In the northern and southern portion of the analysis domain where the mountain slope is relatively gentle and steep, respectively, the radar reflectivity measurements indicate that the precipitation systems exhibit very distinct features, namely, horizontal translation in the north and abrupt intensification in the south. While still far from the southern mountainous region, a north-south oscillation of an east-west-oriented band of strong radar reflectivity (>40 dBZ) with a horizontal span of 20 km is observed. Along the mountain slopes, the band of strong radar reflectivity has a much wider north-south extent. Both the radar and rain gauge observations show that the major precipitation is primarily confined to the windward side of the mountains. An analysis of the saturated Brunt-Väisälä frequency reveals that the upstream atmosphere is statically unstable, which implies that the lifting of the incoming convective cells by the topography will easily trigger precipitation. Thus, most of the moisture will be consumed before the air reaches the leeward side of the mountains. The long duration and the wide range of heavy precipitation in the mountainous regions resulted in a record-breaking average (over the gauges) rainfall amount of 2000 mm over 4 days. The prevailing winds approaching the mountains are from the west. The cross-barrier wind speed has a maximum (?40 m s-1) above the mountain crest that can be reasonably explained by a simplified shallow water model. The capability of applying the weather radar to provide a reliable quantitative estimate of the rainfall over a large area with high temporal and spatial resolution is demonstrated using dual-polarimetric radar data. The potential applications of the knowledge of the wind and precipitation characteristics in hydrology and other fields are addressed in this manuscript.

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

    Microsoft Academic Search

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

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Turcich, Elizabeth; Cranston, Robert

    1994-05-01

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

  17. Comparison of the Scaling Characteristics of Rainfall Derived from Space-based and Ground-based Radar Observations

    NASA Astrophysics Data System (ADS)

    Gebremichael, M.; Over, T. M.; Krajewski, W. F.

    2004-05-01

    The authors compare the scaling characteristics of tropical rainfall derived from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and the S-band ground-based radar (GR). Compared with the PR, the GR has a lower minimum detectable signal (-108 dBm instead of 17 dBZ); a better horizontal resolution (the gate spacing is 250 m, instead of 4.3 km resolution at nadir); and a nonattenuating wavelength (~10 cm instead of 2.2 cm). The differences between the PR and GR radar characteristics and viewing geometries lead to important differences in sensitivity, attenuation, and resolution. Comparison of the scaling characteristics of rainfall derived from the GR and PR is helpful to identify the potential and limitation of the PR. In this work, the authors use the PR and GR data collected from three primary TRMM Ground Validation (GV) sites. This dataset includes 18 months of data from the Houston, Texas, site; 30 months from the Melbourne, Florida, GV site; and 11 months from the Kwajalein Atoll, Republic of Marshall Islands, GV site. The GR data used in this study are the current 2A-53 products prepared by the NASA TRMM Office. Under the assumption of scaling invariance, the authors perform a detailed comparison of the scaling properties of rainfall derived from the PR and GR rainfall products for the three sites. Results using the scaling of moments function show that (1) both products reveal that the scaling parameter, which characterizes the scaling of rainy regions, can be related to the large-scale spatial average rain rate by a one-to-one function, and the function parameters obtained from the PR and GR are remarkably similar; (2) the values of the scaling parameter, which characterizes the curvature of the scaling function, obtained from the PR are consistently lower than those obtained from the GR; and (3) the differences between the PR- and GR-derived scaling characteristics are attributed to the differences in the sensor characteristics, as the temporal sampling of the TRMM PR is shown to adequately capture the scaling properties of rainfall. The authors also investigate the assumption of scaling invariance using a simulation-based approach. Results show that more than 25% of the rain events do not exhibit scaling invariance in moment orders of 0 and 2. The behavior of the deviation from the scaling and its implication on the type of modeling cascade are discussed.

  18. Super-resolution technologies for all-weather sense and avoidance (SAA) radar

    NASA Astrophysics Data System (ADS)

    Zhang, Yan Rockee; Li, Zhengzheng; Wang, Shang; Pan, Yu; Suarez, Hernan

    2011-06-01

    The sense and avoidance (SAA) and due-regard radar systems have strict requirements on size, weight and power (SWaP) and target localization accuracies. Also, the multi-mission capabilities with both weather and hard targets are critical to the survivability of unmanned aerial vehicles (UAV) in the next generation national airspace. The aperture limitations of the aircraft sensor installation, however, have prevented large antennas/arrays to be used. The tradeoffs among frequencies, resolutions and detection range/accuracies have not been fully addressed. Innovative concepts of overcoming the aperture limitation by using a special type of super-resolution technology are introduced. The first technique is based on a combination of thinned antenna array, an extension to the traditional Multiple Signal Classification (MUSIC) technique, and applying a two-dimensional sidelobe mitigation technique. To overcome the degradation of MUSIC-type of approach due to coherent radar signals, a special waveform optimization procedure is used. The techniques for mitigating artifacts due to "thinned" array are also introduced. Simulated results of super-resolution techniques are discussed and evaluated, and the capability of separating multiple targets within aperture-constrained beamwidth is demonstrated. Moreover, the potential capabilities of autonomous weather hazard avoidance are also analyzed.

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

    Microsoft Academic Search

    Witold F. Krajewski; Alexandros A. Ntelekos; Radoslaw Goska

    2006-01-01

    The US National Weather Service (NWS) has installed a large network of weather Surveillance radars (WSR-88D) that provide precipitation maps for the United States. Many of these radars operate in mountainous regions and consequently suffer from beam blockage caused by terrain obstacles. The authors present a methodology for assessing the severity of the beam blockage and outline its implications for

  20. Near Real Time Integration of Satellite and Radar Data for Probabilistic Nearcasting of Severe Weather

    NASA Astrophysics Data System (ADS)

    Pavolonis, M. J.; Cintineo, J.; Sieglaff, J.; Lindsey, D. T.

    2014-12-01

    The formation, maintenance, and severity of thunderstorms that produce large hail, strong winds, and tornadoes are often difficult to forecast due to their rapid evolution and complex interactions with environmental features that are challenging to directly observe. This paper describes an empirical, data driven, approach to forecasting severe convection through fusion of near real time data from several sources. More specifically, data from the Geostationary Operational Environmental Satellites (GOES), the Next Generation Weather Radar (NEXRAD) network, and the Rapid Refresh (RAP) numerical weather prediction (NWP) model are used to drive a naïve Bayesian classifier. Each observation source provides unique information during different periods of storm development (i.e., the pre-storm environment, storm initiation and growth, and hydrometeor intensification). The model is designed to provide warning guidance to forecasters in the near-term (0-60 min), by quantifying several key temporal and spatial attributes of developing convection. The probabilistic model, known as ProbSevere, has been running in near real time at the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS) since April of 2013 and was formally evaluated by National Weather Service (NWS) forecasters at the Hazardous Weather Testbed (HWT) in the spring of 2014. Validation studies and forecaster feedback indicated that the ProbSevere model, which is driven by near real time data, could be used to improve severe weather warning operations. In this paper, we will give an overview of the ProbSevere model, including performance statistics, and describe how the model will benefit from the next generation of GOES satellites (GOES-R).

  1. 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.

  2. 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 used in catchments without gauges in or near the catchment. Uncertainty in rainfall forcing is a major source of uncertainty in discharge predictions, both with lumped and with distributed models. For lumped rainfall-runoff models, the main source of input uncertainty is associated with the way in which (effective) catchment-average rainfall is estimated. Improving rainfall measurements can improve the performance of rainfall-runoff models, indicating their potential for reducing flood damage through real-time control.

  3. 3.16 INTERCOMPARISON OF CHARM DATA AND WSR-88D STORM INTEGRATED RAINFALL

    E-print Network

    Haines, Stephanie L.

    to validate weather radar and lightning data, monitor spatial distributions of precipitation for soil moisture gauge network can also be used to help validate remotely sensed measurements of rainfall, soil moisture of research. The research presented in this paper uses radar data to interpolated from the 24h rain gauge

  4. Lakshmanan,V., 2012: Image processing of weather radar reflectivity data: Should it be done in Z or dBZ?, Electronic J. Severe Storms Meteor., 7 (3), 18.

    E-print Network

    Lakshmanan, Valliappa

    Lakshmanan,V., 2012: Image processing of weather radar reflectivity data: Should it be done in Z or dBZ?, Electronic J. Severe Storms Meteor., 7 (3), 1­8. Image Processing of Weather RadarBZ is better for such applications. 1. Motivation Image processing of weather radar reflectivity fields (the

  5. Performance evaluation of radar and satellite rainfalls for Typhoon Morakot over Taiwan: Are remote-sensing products ready for gauge denial scenario of extreme events?

    NASA Astrophysics Data System (ADS)

    Chen, Sheng; Hong, Yang; Cao, Qing; Kirstetter, Pierre-Emmanuel; Gourley, Jonathan J.; Qi, Youcun; Zhang, Jian; Howard, Ken; Hu, Junjun; Wang, Jun

    2013-12-01

    SummaryThis study evaluated rainfall estimates from ground radar network and four satellite algorithms with a relatively dense rain gauge network over Taiwan Island for the 2009 extreme Typhoon Morakot at various spatiotemporal scales (from 0.04° to 0.25° and hourly to event total accumulation). The results show that all the remote-sensing products underestimate the rainfall as compared to the rain gauge measurements, in an order of radar (-18%), 3B42RT (-19%), PERSIANN-CCS (28%), 3B42V6 (-36%), and CMORPH (-61%). The ground radar estimates are also most correlated with gauge measurements, having a correlation coefficient (CC) of 0.81 (0.82) at 0.04° (0.25°) spatial resolution. For satellite products, CMORPH has the best spatial correlation (0.70) but largely underestimates the total rainfall accumulation. Compared to microwave ingested algorithms, the IR-dominant algorithms provide a better estimation of the total rainfall accumulation but poorly resolve the temporal evolution of the warm cloud typhoon, especially for a large overestimation at the early storm stage. This study suggests that the best performance comes from the ground radar estimates that could be used as an alternative in case of the gauge denial. However, the current satellite rainfall products still have limitations in terms of resolution and accuracy, especially for this type of extreme typhoon.

  6. Pseudowhitening of weather Radar signals to improve spectral moment and polarimetric variable estimates at low signal-to-noise ratios

    Microsoft Academic Search

    Sebastián M. Torres; Christopher D. Curtis; J. R. Cruz

    2004-01-01

    Pseudowhitening of oversampled signals in range is proposed as a method to improve the performance of spectral moment and polarimetric variable estimators on weather surveillance radars. In an attempt to overcome the noise sensitivity of the whitening transformation, a solution based on the minimum mean-square-error criterion is considered first; however, this transformation is less practical than whitening because it requires

  7. On the feasibility of a Doppler weather radar for estimates of drop size distribution using two closely spaced frequencies

    Microsoft Academic Search

    Robert Meneghini; L. Liao; Steven W. Bidwell; G. M. Heymsfield

    2001-01-01

    Dual-frequency weather radar data can be gathered using a single broadband power amplifier and antenna for the purpose of estimating parameters of the hydrometeor size distribution. This is an attractive feature for observation platforms that are limited with respect to mass or available power. Whether useful properties of the scattering medium can be obtained from data of this type is

  8. An optimal design of a cylindrical polarimetric phased array radar for weather sensing

    NASA Astrophysics Data System (ADS)

    Karimkashi, Shaya; Zhang, Guifu

    2012-04-01

    An optimal design of a cylindrical polarimetric phased array radar (CPPAR) for weather sensing is presented. A recently introduced invasive weed optimization (IWO) technique is employed to obtain the desired radiation pattern of the CPPAR. Instead of optimizing each element excitation in a large array (with expensive calculation costs), the modified Bernstein polynomial distribution, defined by seven parameters, is used to optimize the current distribution for the CPPAR. The simulation results show that the desired sidelobe levels (SLLs) and beam width are achieved in a computationally effective manner. Furthermore, the imaged feed arrangement is used to suppress the cross-polarization level. Both co-polar and cross-polar radiation patterns for broadside and off-broadside directions are presented to show the performance of the optimized CPPAR.

  9. 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.

  10. 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 when geo-locating the radar beam (i.e., beam height and arc distance), including non-standard refraction based on the user-input temperature profile. In addition to temperature profile adaptivity, this paper will also summarize the other requirements for this scan strategy program such as detection of low-level boundaries, detection of anvil clouds, reducing the Cone Of Silence, and allowing for times when deep convective clouds will not occur. The adaptive technique will be carefully compared to and benchmarked against the new fixed scan strategy. Specific environmental scenarios in which the adaptive scan strategy is able to optimize and improve coverage and resolution at critical heights, scan time, and/or sample numbers relative to the fixed scan strategy will be presented.

  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 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. Data generated from TRMM and archived at the GDAAC 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.

  12. Near real-time runoff estimation using spatially distributed radar rainfall data 

    E-print Network

    Hadley, Jennifer Lyn

    2004-09-30

    The purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number (CN) method for estimating near real-time runoff for naturalized flow, using high resolution radar ...

  13. Weather

    NSDL National Science Digital Library

    Ms. Stearns

    2008-10-25

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

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

    Microsoft Academic Search

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

    2007-01-01

    The present study investigates regional cloud characteristics over the tropical northwestern Pacific using Tropical Rainfall Measuring Mission (TRMM) data sets such as rain rate, radar reflectivity, and passive microwave radiometer polarization corrected temperature (PCT). In particular, the tropical northwestern Pacific is divided into two surface rain maxima regions: the South China Sea (SCS) and the Philippine Sea (PS). The TRMM

  15. 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 presented. Focus is on the relationship of radar backscatter cross sections at multiple wavelengths, apparent diurnal temperature excursions identified in multi-temporal TIMS images, surface geometries related to weathering style, and parent bedrock lithology.

  16. Effects of rainfall on weathering rate, base cation provenance, and Sr isotope composition of Hawaiian soils

    Microsoft Academic Search

    BRIAN W. STEWART; R OSEMARY C. CAPO; OLIVER A. CHADWICK

    2001-01-01

    A climate transect across the Kohala Peninsula, Hawaii provides an ideal opportunity to study soil processes and evolution as a function of rainfall. The parent material is the ?150 ka Hawi alkali basalt aa flow, and median annual precipitation (MAP) changes from ?16 cm along the west coast to ?450 cm in the rain forest near the crest of the

  17. 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.

  18. Spaceborne Radar Would Measure Rain And Clouds

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Kellogg, Kent H.

    1992-01-01

    Report describes conceptual design of spaceborne radar system mapping precipitation and clouds at mid-latitudes to provide data for research on global weather and climate. Radar operates at two frequencies. Lower (35 GHz) provides vertical profiles of rainfall at rates up to 20 mm/h and enables probing of cirrus clouds. Higher (94 GHz) enables detection and quantitative measurements of clouds of all types and provides rain profiles at rates up to 10 mm/h.

  19. Development and application of GIS based K-DRUM for flood runoff simulation using radar rainfall

    Microsoft Academic Search

    Jin Hyeog Park; Young Teck Hur

    The aim of this paper is to develop a physical based distributed runoff model for flood simulation considering spatially and temporally varied rainfall and to evaluate the feasibility of an offline mode under typhoon and convective storm events for Korean watershed. Additionally, an auto-calibration method for initial soil moisture conditions that have an effect on discharge was proposed, and Namgang

  20. Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission Precipitation Radar and

    E-print Network

    Frequency of tropical precipitating clouds as observed by the Tropical Rainfall Measuring Mission July 2007. [1] Convective clouds in the tropics can be grouped into three categories: shallow clouds with cloud top heights near 2 km above the surface, midlevel congestus clouds with tops near the 0°C level

  1. Experimental tests of methods for the measurement of rainfall rate using an airborne dual-wavelength radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Nakamura, K.; Ulbrich, C. W.; Atlas, D.

    1989-01-01

    Several attenuation-based methods for estimating the rainfall rate were applied to measurements made by an airborne dual-wavelength radar operating at 0.87 cm, the K(a)-band, and at 3 cm, the X-band. These methods included the traditional Z-R methods, designated Z(X)-R and Z(K)-R for the X- and K(a) band wavelengths, respectively; single- and dual-wavelength surface reference techniques (SRT and DSRT, respectively); and standard dual-wavelength methods with and without range-averaging. As the primary sources of error for these methods are nearly independent, agreement among the rain rates obtained with these methods would lend confidence in the results. Correlation coefficients obtained between the rainfall rates with the Z(X)-R and DSRT methods were generally between 0.7 and 0.9. Good agreement among the methods occurred most often in stratiform rain for rain rates betwen a few mm/hr to about 15 mm/hr, i.e., where attenuation at the shorter wavelength is significant but not so severe as to result in a loss of signal.

  2. Flash flood prediction using an uncalibrated hydrological model and radar rainfall data in a Mediterranean watershed under changing hydrological conditions

    NASA Astrophysics Data System (ADS)

    Rozalis, Shahar; Morin, Efrat; Yair, Yoav; Price, Colin

    2010-11-01

    SummaryFlash floods cause some of the most severe natural disasters in Europe but Mediterranean areas are especially vulnerable. They can cause devastating damage to property, infrastructures and loss of human life. The complexity of flash flood generation processes and their dependency on different factors related to watershed properties and rainfall characteristics make flash flood prediction a difficult task. In this study, as part of the EU-FLASH project, we used an uncalibrated hydrological model to simulate flow events in a 27 km2 Mediterranean watershed in Israel to analyze and better understand the various factors influencing flows. The model is based on the well-known SCS curve number method for rainfall-runoff calculations and on the kinematic wave method for flow routing. Existing data available from maps, GIS and field studies were used to define model parameters, and no further calibration was conducted to obtain a better fit between computed and observed flow data. The model rainfall input was obtained from the high temporal and spatial resolution radar data adjusted to rain gauges. Twenty flow events that occurred within the study area over a 15 year period were analyzed. The model shows a generally good capability in predicting flash flood peak discharge in terms of their general level, classified as low, medium or high (all high level events were correctly predicted). It was found that the model mainly well predicts flash floods generated by intense, short-lived convective storm events while model performances for low and moderate flows generated by more widespread winter storms were quite poor. The degree of urban development was found to have a large impact on runoff amount and peak discharge, with higher sensitivity of moderate and low flow events relative to high flows. Flash flood generation was also found to be very sensitive to the temporal distribution of rain intensity within a specific storm event.

  3. Spaceborne radar measurements of verticle rainfall velocity: the non-uniform beam filling considerations

    NASA Technical Reports Server (NTRS)

    Im, E.; Tanelli, S.; Durden, S. L.; Facheris, L.; Giuli, D.; Smith, E. A.; Haddad, Z. S.

    2001-01-01

    In this paper, the characteristics of the Doppler power spectrum observed by a spaceborne precipitation radar, under on Uniform Beam Filling (NUBF) condion will be presented, and the expected performance of some standard Doppler estimators and that of a new inversion technique will be investigated and compared.

  4. Intelligent weather agent for aircraft severe weather avoidance

    E-print Network

    Bokadia, Sangeeta

    2002-01-01

    avoidance capability has increased. In this thesis, an intelligent weather agent is developed for general aviation aircraft. Using a radar image from an onboard weather radar, the intelligent weather agent determines the safest path around severe weather...

  5. Weather

    NSDL National Science Digital Library

    Rachelle Tuttle

    2005-10-25

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

  6. The effects of earth partial specular reflection on the quantitative rainfall-rate measurements by radar

    Microsoft Academic Search

    Ma Zhenhua

    1985-01-01

    The equations for calculating the echo power from meteorological targets and the energy distribution within radar beam were\\u000a derived, by taking the earth curvature, atmospheric refractivity gradient, reflection factor and the roughness of the earth's\\u000a surface into consideration. The estimation based on these equations shows that the rain echo power may deviate from its normal\\u000a value by a factor of

  7. Regional estimation of torrent hazards by analysing weather radar data and catchment characteristics

    NASA Astrophysics Data System (ADS)

    Pistotnik, G.; Klebinder, K.; Chifflard, P.; Kirnbauer, R.; Haiden, T.

    2009-04-01

    Torrent hazards in mountain areas in the eastern part of Lower Austria are mostly triggered by convective rainfall events during thunderstorms. The Austrian Avalanche and Torrent Control Service commissioned a project for a regional analysis of torrent hazard potential in the region Bucklige Welt / Wechselland as the basis for detailed investigations and torrent control measures which will be planned later, taking into account the hazard potential of individual streams, the most dangerous first, the less dangerous later. Thus, the following problems had to be analysed: Are there any typical points of origin of convective storms in or near the project region? Are there any typical tracks of these storms endangering the region, and what is their extent and lifetime? Which catchments generate more and which less runoff caused by the same precipitation amount? For approaching the meteorological part of the integrated problem the precipitation is estimated from radar data on a 15 minutes basis with a spatial resolution of 1 km, because no sufficient precipitation measurements are available. Within the nowcasting system INCA (Integrated Nowcasting through Comprehensive Analysis) of the Central Institute for Meteorology and Geodynamics (ZAMG) these radar data are combined with satellite data, ground data, model data from the meteorological local area model "ALADIN Vienna" and with a digital terrain model of 1 km grid space. Thus, a continuous set of precipitation fields were calculated for the years 2003 to 2007 with a temporal resolution of 15 minutes and a local resolution of 1 km. Based on this data set convective cells were identified and their tracks analysed. If a precipitation intensity of 3,8 mm/15 min was exceeded, in accordance with experiences of the meteorological remote sensing group of the ZAMG, it was a-priori assumed that this was a convective storm. According to this threshold nearly 350 convective events were automatically extracted. After discarding approximately about one third of these events as spurious the tracks of the remaining 245 cells were identified. The locations of the origin of these cells were in accordance with the experience of synoptic meteorologists, and the tracks, as to their motion direction averaged over the whole observation period of five years, followed the main wind direction in the region. Within the day of the event and from one to the next time step of 15 minutes, however, the motion of the cells was rather erratic, and their motion vectors could be described by normal distributions for speed and angle. As to their shape, the cells can be approximated by circles of changing radius: first small, then growing to a maximum size and then shrinking. The maximum diameter can be approximated by a two parameter log normal distribution, and such is the lifetime of the cells and the rainfall intensity. Due to the short observation period the intensities cannot be directly used for design purposes but have to be extrapolated to the design intensities supplied by the Hydrological Service. Intensive field studies were performed for assessing the runoff behaviour of the catchments. On nine locations irrigation experiments took place by use of a transportable spray irrigation installation with rain intensities of approximately 100mm/h on plots of 80m² and they were accompanied by soil moisture measurements with TDR probes. They were situated in two profiles of the irrigation plots and in 5, 15, 25 and 40 cm depth respectively. Six undisturbed soil cores were taken with cylindrical samplers (200 cm³ volume each) in four depths down to 50 cm. The samples were analysed with respect to their soil type, soil texture, bulk density, porosity and saturated conductivity. Thus, the results of the irrigation experiments could be thoroughly interpreted with the additional information on soil moisture dynamics and physical characteristics. For the irrigation plots and for additional 350 locations standardized investigations referring to vegetation, surface roughness, upper soil layers, deep soil

  8. Dual polarisation C-band weather radar imagery of the 6 August 2012 Te Maari Eruption, Mount Tongariro, New Zealand

    NASA Astrophysics Data System (ADS)

    Crouch, John F.; Pardo, Natalia; Miller, Craig A.

    2014-10-01

    The 6 August 2012 eruption of Mt. Tongariro from Upper Te Maari Crater in the central North Island of New Zealand was the first volcanic eruption observed by an operational weather radar in New Zealand, and is believed to be one of only a small number of eruptions observed by a dual-polarisation radar worldwide. The eruption was also observed by a GeoNet webcam, and detailed ash deposit studies have permitted analysis of the plume characteristics. A combination of radar and webcam imagery show 5 pulses within the first 13 min of the eruption, and also the subsequent ash transport downwind. Comparison with ash samples show the radar was likely detecting ash particles down to about 0.5 mm diameter. The maximum plume height estimated by the radar is 7.8 ± 1.0 km above mean sea level (amsl), although it is possible this may be a slight under estimation if very small ash particles not detected by the radar rose higher and comprised the very top of the plume. The correlation coefficient and differential reflectivity fields that are additionally measured by the dual polarisation radar provide extra information about the structure and composition of the eruption column and ash cloud. The correlation coefficient easily discriminates between the eruption column and the ash plume, and provides some information about the diversity of ash particle size within both the ash plume and the subsequent detached ash cloud drifting downwind. The differential reflectivity shows that the larger ash particles are falling with a horizontal orientation, and indicates that ice nucleation and aggregation of fine ash particles was probably occurring at high altitudes within 20-25 min of the eruption.

  9. A Study on Removal of Radial Interference Echo with Weather Radar

    Microsoft Academic Search

    Zhou Jiao; Gao Yuchun

    2010-01-01

    Electromagnetic disturbance (EMI) is an unpredictable event which often cause abnormal radar echo. EMI enables invariant radial interference echo (features such as sun-strobes) existing in certain directions in radar echo charts at many radar stations, the interference echo and the precipitation echo overlap in many regions. The paper key research has analyzed removal of interference echo which laps over precipitation

  10. Investigation of Rainfall Spatial Variation Scale to be Considered in Runoff Simulation Using Distributed Model and Radar Data

    Microsoft Academic Search

    Yutaka Ichikawa; Yasuto Tachikawa; Michiharu Shiiba

    A rainfall spatial variation scale to be considered in a runoff simulation will be investigated using mesh-type rainfall data and a distributed runoff model. At first, a runoff simulation is conducted by using a mesh-type rainfall data as it is, and the result is regarded as a standard result. As the next step, the rainfall data is averaged in some

  11. 6/18/14, 9:45 AMWeather app teaches kids to read radar with the goal of saving l Page 1 of 2http://www.okcfox.com/story/25743818/weather-app-teaches-kids-to-read-radar-with-the-goal-of-saving-lives

    E-print Network

    McGovern, Amy

    6/18/14, 9:45 AMWeather app teaches kids to read radar with the goal of saving l Page 1 of 2http://www.okcfox.com/story/25743818/weather-app-teaches-kids-to-read-radar-with-the-goal-of-saving-lives Weather app teaches kids CDT By: Rebecca Schleicher, Primetime Reporter - bio | email Kids can save lives when severe weather

  12. Weather

    NSDL National Science Digital Library

    Ms. Hendricks

    2007-12-06

    Introduction: How much do you know about weather? What kinds of weather do we have surrounding us? What is the weather like today? You may know a lot about weather already, you may not. Either way, you will learn more now as we take a look into what causes our weather and the methods we use to record and predict it. We will all become meteorologists, which are scientists who study the atmosphere and can predict weather. Put on your raincoats, and lets started! Task: You are the resident meteorologist at a local news station. It is your job to record and predict the weather each day, and then present it that night on the evening news. Not only should you be able to show the weather that we will be experiencing right ...

  13. RADAR PRINCIPLES I Introduction

    E-print Network

    Sato, Toru

    ) bands. Antenna size of weather radarsis a few to about ten metersin diameter, but an} atmospheric radar atmospheric radars have antennas witli dialneter of 10- 300 in. Weather radars cover a wide horizontal areaRADAR PRINCIPLES I Introduction Radar is a general technique, willcli has a wide range

  14. Weather

    NSDL National Science Digital Library

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

  15. Weather

    NSDL National Science Digital Library

    Miss Jennie

    2009-10-22

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

  16. 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 associated with explosive eruptions is generally produced by the rapid expansion of the gas-particle mixture within the conduit and, in consequence, it is related to the dynamics of the volume outflow and thus to the intensity of the eruption. Infrasound is closely linked to the magma fragmentation process. By combining data from ground surveys and remote sensing measurements, it is possible to gain more insights into tephra detection and distribution. Microwave scanning radars can be exploited to extract tephra spatial-temporal distribution in proximity of the volcano vent. Radar detection of ash clouds is a cumbersome problem, as their signature can be confused with that of hydrometeors. On the other hand, infrasonic arrays can provide a very accurate signal about the onset of a volcanic fountain, even though not necessarily discriminating between lava and ash eruptions. In this work we illustrate the methodology to combine microwave radar data with infrasonic measurements using, as a case study, the eruption of 2010 Eyjafjallajökull. The probabilistic detection module of the Volcanic Ash Radar Retrieval (VARR) physically-based technique is illustrated. The ash detection methodology is based on the temporal analysis of radar volumes of reflectivity and geographical information for the considered specific area. The infrasonic array signal is coupled with radar data to enhance the VARR probability of ash detection. Moreover, mass flow rates estimated from radar measurements are compared with those retrieved from infrasonic arrays and derived from simplified analytical eruption models.

  17. 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 providing insights on the use of radar QPE for hydrological design studies.

  18. An X-band solid-state FM-CW weather radar

    Microsoft Academic Search

    L. P. Ligthart; L. R. Nieuwkerk

    1990-01-01

    FM-CW radar has grown to a mature state owing to new breakthroughs in microwave and computer hardware. Applications of FM-CW radar so far have been mainly in the field of tropospheric research, meteorology and ship navigation. The paper describes a radar to be used for rain-rate determination and rain-cell contouring. The central themes are system fundamentals, system design and construction,

  19. 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.

  20. Applicability of radar observations to the prediction of storm runoff

    E-print Network

    Johnson, Odell Monroe

    1967-01-01

    of Depaverne. (Yiembe~ 1967 (Yonwh) (Yea ) ABSTRACT Rainfall-runoff relaL'ronships fox 18 storms over the Little Nashita River basin in Oklahoma are studied in order to develop a method for predicting storm losses based on weather-radar observational..., for the use of their computer facilities. Credit is due Mr. M. A. Hartman, Chief Research Engineer, Agricultural Research Service, Chickasha, Oklahoma, for his assistance in obtaining treamflow and rainfall data from records maintained by the Agricultural...

  1. Radar

    Microsoft Academic Search

    James R. Zimbelman; Kenneth S. Edgett

    1994-01-01

    Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

  2. 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 the appropriate applications for the 45 WS mission. These include forecasting the onset of lightning, the cessation of lightning, convective winds, and hopefully the inference of electrical fields in clouds. This presentation will report on the results achieved so far in the project.

  3. 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 index flood technique are used in the RFA. A bootstrap technique procedure is carried out to account for the uncertainty in the distribution parameters to construct 90% confidence intervals (i.e., 5% and 95% confidence limits) on AMS-based precipitation frequency curves.

  4. MicroRadarNet: a Network of Integrated High-Resolution Weather Micro Radars to Service Tracking and Forecasting of Local Precipitation Patterns

    NASA Astrophysics Data System (ADS)

    Turso, S.; Terzo, O.; Gabella, M.; Perona, G.

    2010-09-01

    MicroRadarNet (MRN) is a network of high-resolution, low-cost, low-power consumption micro radars for continuous, unattended meteorological monitoring. The MRN project started in the framework of the European INTERREG IIIB Alpine Space Programme (within the FORALPS project) since 2004 and was developed and operated by the Remote Sensing Group at the Politecnico di Torino from its early design stages. MRN is currently under its release and operational validation phase, cooperating with professional weather operators (e.g. civil protection offices) to run extensive on-field tests. The key aspects of MRN are a short range strategy (about thirty kilometers) and the implementation of an effective sensor network approach. Raw spatial and temporal data is processed on-board in real-time, yielding a consistent evaluation of the information from the sensor and compressing the data to be transmitted. Network servers receive and merge the data sets coming from each unit yielding a synthetic, high-resolution plot of meteorological events (updated every minute). This networked approach implies in turn a sensible reduction of the overall operational costs, including management and maintenance aspects, if compared to the traditional long range C-band approach. An ever-growing database of meteorological events is being collected, thus providing a real-data test bench to refine assessment and data enhancement algorithms. Assessment techniques have been adopted for the estimation of precipitation, based on systematic rain gauges comparisons. Efforts were also devoted to the design and implementation of specific decluttering algorithms. New techniques to mitigate the effect of co-channel interference sources are also under testing. It is shown how these enhancement algorithms further improve the assessment process raising the overall data quality. Furthermore, new data analysis modules for the identification of precipitation patterns are being evaluating, including tracking routines for the short term prediction of meteorological cells motion and morphing. We strongly expect that these enhancements will be of some interest to the final users, contributing to the relevance of the provided weather information. Finally, particular attention has been devoted to set up efficient data availability and presentation mechanisms in other to ease weather services access for a broad range of purposes. Up-to-date Web techniques have been implemented accordingly. A consistent amount of case studies clearly shows that MicroRadarNet has enough potentialities to act as a fast-reacting weather monitoring tool. The proposed strategy, based on a network of short range radars, shall effectively collect high-resolution quality datasets while lowering the overall operational costs. This could prevent, by design, the volumetric resolution loss at higher ranges, as well as the need for atmospheric corrections and the shielding shortcomings which typically occur in orographically complex areas.

  5. 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 discussed.

  6. High resolution fire danger modeling : integration of quantitative precipitation amount estimates derived from weather radars as an input of FWI

    NASA Astrophysics Data System (ADS)

    Cloppet, E.; Regimbeau, M.

    2009-09-01

    Fire meteo indices provide efficient guidance tools for the prevention, early warning and surveillance of forest fires. The indices are based on meteorological input data. The underlying approach is to exploit meteorological information as fully as possible to model the soil water content, biomass condition and fire danger. Fire meteorological danger is estimated by Météo-France at national level through the use of Fire Weather Index. The fire index services developed within the PREVIEW project (2005-2008) offer for the first time very high resolution mapping of forest fire risk. The high resolution FWI has been implemented in France complementary to the existing EFFIS operated by the Joint Research Center. A new method (ANTILOPE method) of combining precipitation data originating from different sources like rain gauges and weather radar measurements has been applied in the new service. Some of the advantages of this new service are: · Improved detection of local features of fire risk · More accurate analysis of meteorological input data used in forest fire index models providing added value for forest fire risk forecasts · Use of radar precipitation data "as is” utilizing the higher resolution, i.e. avoiding averaging operations The improved accuracy and spatial resolution of the indices provide a powerful early warning tool for national and regional civil protection and fire fighting authorities to alert and initiate forest fire fighting actions and measures.

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

    Microsoft Academic Search

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

    2007-01-01

    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

  8. All-weather perception for man-portable robots using ultra-wideband radar

    Microsoft Academic Search

    Brian Yamauchi

    2010-01-01

    Autonomous man-portable robots have the potential to provide a wide range of new capabilities for both military and civilian applications. Previous research in autonomy for small robots has focused on vision, LIDAR, and sonar sensors. While vision and LIDAR work well in clear weather, they are seriously impaired by rain, snow, fog, and smoke. Sonar can penetrate adverse weather, but

  9. 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.

  10. Weather

    NSDL National Science Digital Library

    Edheads offers a Macromedia Flash Player enhanced interactive module allowing students to predict the weather by examining weather maps. Through this website, users can become familiar with the concepts of warm and cold fronts, wind direction and speed, air pressure, and humidity. Teachers looking to incorporate this site in their classroom can check out the "Teacher's Guide" for helpful hints on using the site with students.

  11. 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-channel digital receiver has been successfully deployed as a key component in the recently developed National Aeronautical and Space Administration (NASA) Global Precipitation Measurement (GPM) Dual-Frequency Dual-Polarization Doppler Radar (D3R). The D3R is the principal ground validation instrument for the precipitation measurements of the Dual Precipitation Radar (DPR) onboard the GPM Core Observatory satellite scheduled for launch in 2014. The D3R system employs two broadly separated frequencies at Ku- and Ka-bands that together make measurements for precipitation types which need higher sensitivity such as light rain, drizzle and snow. This research describes unique design space to configure the digital receiver for D3R at several processing levels. At length, this research presents analysis and results obtained by employing the multi-carrier waveforms for D3R during the 2012 GPM Cold-Season Precipitation Experiment (GCPEx) campaign in Canada.

  12. Radar rain field evaluation and possible use of its high temporal and spatial resolution for hydrological purposes

    NASA Astrophysics Data System (ADS)

    Morin, J.; Rosenfeld, D.; Amitai, E.

    1995-11-01

    The purpose of this paper is to show how accurate radar-estimated rainfall, with good temporal and spatial resolution, can be used for hydrological purposes. A recent methodological advance in rainfall measurement using conventional weather radars has made it possible to account for much of the variation between the precipitation radar echo intensity and rain intensity. A method known as the window probability matching method (WPMM) was applied to radar measurements over several catchment areas in central Israel. Comparison of daily raingauge measurements with radar rainfall estimates demonstrated good agreement. The standard error of radar-estimated rainfall was only 7% for a storm with a total average accumulation of 328 mm. Several case studies are provided which demonstrate the advantage of having an accurate rain field for calculating excess rainfall for each of the area grid squares in the watershed. Storm excess rainfall for different time durations depends strongly not only on the area size, but also on the differences in the rainfall intensity sequences. Accurate radar rain fields can permit dynamic calculations to be made along the storm path.

  13. Weather-type downscaling of seasonal predictions to daily rainfall characteristics over the Pacific-Andean basin of Ecuador and Peru

    NASA Astrophysics Data System (ADS)

    Pineda, Luis; Willems, Patrick

    2015-04-01

    A weather-type downscaling of seasonal predictions to daily rainfall characteristics is conducted over the Pacific-Andean region of Ecuador and Peru (PAEP) in NW South-America using a non homogenous hidden Markov model (NHMM) and retrospective seasonal information from general circulation models (GCMs). First, a HMM is used to diagnose four states which play distinct roles in the Dec-May rainy season. The estimated daily-states fall into one pair of wet states, one dry and one transitional dry/wet state, and show a systematic seasonal evolution together with intra-seasonal and inter-annual variability. The first wet-state represents region-wide wet conditions, while the second one represents north-south gradients. The former could be associated with the annual moisture off-shore the PAEP region, thermally driven by the climatological maximum of sea surface temperatures in El Niño 1.2 region. The latter corresponded with the dynamically noisy component of the PAEP rainfall signal, associated with the annual displacement of the Inter-tropical convergence zone. Then, a 4-state NHMM is coupled with GCM information to simulate daily sequences at each station. Simulations of the GCM-NHMM approach represent well daily rainfall characteristics at station level. The best skills were found in reproducing the inter-annual variation of seasonal rainfall amount and mean intensity at regional-averaged level with correlations equals to 0.60 and 0.64, respectively.

  14. USING A DUAL-POLARIMETRIC WEATHER RADAR SIMULATOR TO INVESTIGATE MICROWAVE BACKSCATTER FROM BIRDS

    Microsoft Academic Search

    Phillip B. Chilson; Kara Bolognini; Boon Leng Cheong; Jeff Kelly

    Aeroecology, the discipline that embraces and inte- grates the domains of atmospheric science, ecology, earth science, geography, computational biology, and engineering was aptly named and created to study the effects of the environment on the organisms that reside in and depend on the boundary layer for survival (Kunz et al., 2008). Aeroecology has incredible potential within the realm of radar

  15. On the Feasibility of Precisely Measuring the Properties of a Precipitating Cloud with a Weather Radar 

    E-print Network

    Runnels, R.C.

    1967-01-01

    of the liquid-water content by means of this equation. The version of the continuity equation developed in this study represents an improvement over forms used previously. The new version accounts for the downward development of a radar echo at speeds faster...

  16. Combining and comparing weather radar measurements and rain gauge measurements of precipitation in a fruit growing area

    NASA Astrophysics Data System (ADS)

    Sivertsen, T. H.; Rafoss, T.

    2003-04-01

    A small fruit growing area of southern Norway is chosen as a pilot area. This area contains four automated meteorological stations owned by The Norwegian Crop Research Institute. The measurements made at the stations are hourly recordings of precipitation, air temperature, leaf wetness and relative humidity of the air, plus some additional measurements at some stations. The area has a relatively smooth topography with hills and no mountains. The highest point is located about 300 m above the sea level, and the lowest 15 m above sea level. The remote sensing research group at The Norwegian Meteorological Institute is providing the hourly radar measurements of precipitation, from two different weather radars. All the precipitation data used is documented according to a system developed by The Norwegian Crop Research Institute, and for the growing season ahead data will be distributed to the local private extension service, but this year there will be no development of biological models serving the fruit growers (apple scab etc) using all the additional relevant data. The outcome of the use of the operational use of the data in the coming growing season, will be comparing the data from the different sources, and looking closer at the possible significance of the use of a documentation system for the data from different sources. Finally the quality of the data is discussed, as well as the possible steps to be taken for future and extended use of such data.

  17. 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.

  18. 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.

  19. 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.

  20. Thunderstorm lightning and radar characteristics: insights on electrification and severe weather forecasting 

    E-print Network

    Steiger, Scott Michael

    2007-04-25

    are higher in altitude when the balloon ascent rate (a proxy for updraft strength) is greater. Hence, charge regions detected by VHF networks like LDAR II (Rison et al. 1999, Coleman et al. 2000, Bruning et al. 2002, Detwiler et al... that the magnitudes and vertical shear of the environmental wind are key parameters in lightning location (as shown by the distribution of VHF impulses) relative to severe storm structure. The lightning data from the LDAR II overlaid on radar...

  1. Workshop Report on NEXRAD-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    Microsoft Academic Search

    Eric A. Smith; V. Chandra Chandrasekar; Shuyi Chen; Gregory Holland; Ramesh Kakar; Simone Tanelli; Frank Marks; Gregory Tripoli

    NEXRAD-In-Space (NIS) is a mission concept to provide a geostationary satellite Doppler radar. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS 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

  2. Weather

    NSDL National Science Digital Library

    Ms. Caitlin

    2009-10-21

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

  3. 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 talk will give a brief summary of the NIS instrument concept, the current technology status, the anticipated impacts on hurricane monitoring and model prediction, and the future science and technology roadmap.

  4. 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 and quantify the sources of uncertainty in such rainfall maps, but also to test the actual and optimal performance of one commercial microwave network from one of the cellular providers in The Netherlands.

  5. 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.

  6. Flash flood prediction using an un-calibrated hydrological model and radar rainfall data in a Mediterranean watershed under changing hydrological conditions

    NASA Astrophysics Data System (ADS)

    Rozalis, Shahar; Morin, Efrat; Yair, Yoav; Price, Colin

    2010-05-01

    Flash floods are one of the most severe natural disasters in Europe in general and in Mediterranean areas in particular. They can cause severe damage to property, infrastructures and loss of human life. The complexity of flash-flood generation processes and their dependency on different factors related to watershed properties and rainfall characteristics make flash flood prediction a difficult task. In this study, as a part of the EU-FLASH project, we use an un-calibrated hydrological model to simulate flow events in a 27 km2 Mediterranean watershed in Israel and to analyze and better understand the various factors affecting them. The model is based on the well-known SCS Curve Number method for rainfall-runoff calculations and on the kinematic wave method for flow routing. Existing data available from maps, GIS and field studies have been used to define model parameters, and no further calibration has been conducted to get a better fit between computed and observed flow data. The model rainfall input was obtained from the high temporal and spatial resolution radar data adjusted to rain gauges. 20 flow events which occurred within the study area along a 15 years period have all been analyzed. The model shows a generally good prediction capability (e.g., r2=0.7 for peak discharge) which is mainly due to the high performance in predicting flash-floods generated by intense, short-lived convective storm events (r2=0.9). A better performance is achieved when considering the flood level; then the model is able to predict all events defined as high level flood events. The degree of urban development was found to have a large effect on runoff amount and peak discharge with higher sensitivity of moderate and low flow events relative to high flows. Flash-flood generation was also found to be very sensitive to the temporal distribution of rain intensity within the specific storm event.

  7. 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.

  8. Use and Interpretation of Radar

    NSDL National Science Digital Library

    John Nielsen-Gammon

    1996-01-01

    This undergraduate meteorology tutorial from Texas A&M University discusses the basic principles of operation of weather radars, describes how to interpret radar mosaics, and discusses the use of radar in weather forecasting. Students learn the relationship between range and elevation and how to use radar images and mosaics in short-range forecasting.

  9. 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. All this complemented with the application of statistical techniques for data analysis and exploration. The main contribution of this research is the creation of tools to be used in numerical modeling with forecasting purposes, aiming to improve the resolution given by mesoscale models, which are currently used for weather forecast in Colombia.

  10. 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 catchment may be considered useful or not to describe the rainfall depending on the type of rainfall. For widespread rainfalls, further rain gauges can give a reliable measurement, because the spatial correlation decreases slowly with the distance between the rain gauge and the debris-flow initiation area. Contrarily, local storm cells show higher space-time variability and, therefore, representative rainfall measurements are obtained only by the closest rain gauges. In conclusion, the definition of rainfall thresholds is a delicate task. When the rainfall records are coming from gauges that are outside the catchment under consideration, the data should be carefully analysed and crosschecked with radar data (especially for small convective cells).

  11. The Waves to Weather Challenge: Do Large-Scale Equatorial Waves Modulate Regional Rainfall in Southern Vietnam?

    NASA Astrophysics Data System (ADS)

    Fink, A. H.; van der Linden, R.; Phan-Van, T.; Pinto, J. G.

    2014-12-01

    About 85% of the annual precipitation in southern Vietnam (ca. 8-12°N, 104-110°E) occurs during the southwest monsoon season (June to October). Large-scale equatorial waves like the Madden-Julian Oscillation (MJO) and Convectively Coupled Equatorial Waves (CCEWs) are known to modulate the large-scale convective activity, often indicated by variations in (filtered) satellite-observed outgoing longwave radiation (OLR) anomalies. The present contribution analyses and quantifies the role of the MJO and CCEWs for rainfall not only in southern and central Vietnam as a whole, but also for smaller climatological sub-regions. Using circum-equatorial NOAA OLR (15°S-15°N), prominent spectral peaks are identified in wavenumber-frequency diagrams along the dispersion curves for the solutions of the shallow water equations. They are interpreted as CCEWs. Meridionally averaged wave-filtered OLR and its time derivatives are used to define phases and amplitudes of CCEWs. This will allow determining active and inactive phases of CCEWs in the vicinity of Vietnam. Eastward propagating deep convection is also related to the 30-90-day MJO. The OLR MJO Index (OMI) is used for the definition of convectively active and inactive phases of the MJO. TRMM 3B42 V7, APHRODITE MA V1101 data, and rain gauge measurements are used to investigate the relation between tropical wave phases and amplitudes and precipitation in southern and central Vietnam and adjacent regions. Results using the OMI are compared with those using the Real-time Multivariate MJO (RMM) Index. The major findings are: (a) Precipitation amounts in southern Vietnam are higher during convectively active phases of the MJO and CCEWs. The waves differ in terms of their relative importance for rainfall enhancement. (b) For increasing CCEW amplitudes, the difference between area-averaged precipitation during inactive and active phases increases. We provide evidence that precipitation amounts are higher when multiple wave types are in their convectively active phases over the Vietnam region.

  12. Flood Monitoring using X-band Dual-polarization Radar Network

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  13. 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.

  14. Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm

    Microsoft Academic Search

    D. Leuenberger; A. Rossa

    2007-01-01

    Summary  Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes\\u000a for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme\\u000a within a meso-? scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration\\u000a is given to the model’s dynamical response to the forcing as

  15. Linking the Annual Variation of Snow Radar-derived Accumulation in West Antarctica to Long-term Automatic Weather Station Measurements

    NASA Astrophysics Data System (ADS)

    Feng, B.; Braaten, D. A.; Gogineni, P.; Paden, J. D.; Leuschen, C.; Purdon, K.

    2013-12-01

    Understanding the snow accumulation rate on polar ice sheets is important in assessing mass balance and ice sheet contribution to sea level rise. Measuring annual accumulation on a regional scale and extending back in time several decades has been accomplished using the Center for Remote Sensing of Ice Sheets (CReSIS) Snow Radar on the NASA DC-8 that is part of NASA's Ice-Bridge project. The Snow Radar detects and maps near-surface internal layers in polar firn, operating from 2- 6 GHz and providing a depth resolution of ~4 cm. During November 2011, Snow Radar data were obtained for large areas of West Antarctica, including a flight segment that passed within ~70 km of Byrd Station (80°S, 119°W). Byrd Station has a very long automatic weather station (AWS) record, extending from present to 1980, with 3 relatively brief gaps in the record. The AWS data for Byrd Station were obtained from the Antarctic Meteorological Research Center (AMRC) at the University of Wisconsin. The L1B Snow Radar data products, available from the National Snow and Ice Data Center (NSIDC), were analyzed using layer picking software to obtain the depth of reflectors in the firn that are detected by the radar. These reflectors correspond to annual markers in the firn, and allow annual accumulation to be determined. Using the distance between the reflectors and available density profiles from ice cores, water equivalent accumulation for each annual layer back to 1980 is obtained. We are analyzing spatial variations of accumulation along flight lines, as well as variations in the time series of annual accumulation. We are also analyzing links between annual accumulation and surface weather observations from the Byrd Station AWS. Our analyses of surface weather observations have focused on annual temperature, atmospheric pressure and wind extremes (e.g. 5th and 95th percentiles) and links to annual snow accumulation. We are also examining satellite-derived sea ice extent records for the Bellingshausen and Amundsen seas sector (60°W-120°W) over the same 31-year time period and comparing results to annual snow accumulation. Results from this work will be presented at the meeting.

  16. Using Independent NCDC Rain Gauges to Analyze Precipitation Values from the OneRain Corporation Algorithm and the National Weather Service Procedure

    Microsoft Academic Search

    S. M. Martinaitis; H. E. Fuelberg; J. L. Sullivan; C. Pathak

    2007-01-01

    Two widely used procedures for optimally combining radar- and gauge-derived rainfall are those of the OneRain Corporation and the National Weather Service (NWS). The NWS procedure, called the Multi-sensor Precipitation Estimator (MPE), produces an hourly product on the 4×4 km Hydrologic Rainfall Analysis Project (HRAP) grid. MPE is used operationally by local NWS offices and NWS River Forecast Centers (RFCs).

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

    NASA Astrophysics Data System (ADS)

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

    1995-03-01

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

  18. Weather Radar and Hydrology (Proceedings of a symposium held in Exeter, UK, April 2011) (IAHS Publ. 351, 2011).

    E-print Network

    Lovejoy, Shaun

    and versatile. X-band radar networks are thus planned around megalopolises. However, to fully take advantage. They have several attractive features: reduced transmitted power and antenna size, and reduced sensitivity by INED and 4 X-band radars managed by other institutions. Similar networks are to be deployed around 10

  19. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. AP-25, NO. 4, JULY 1977 Analysis of Weather Radar Return

    E-print Network

    Zhang, Yan

    Radar Return D. v.PAYNE, MEMBER,IEEE 457 Abstr~ct-Amathematicalmodel of detectedclutterfrom an air of radar return from hydro- meteorsatthe same nominal rangeand scan angle.It is developed fromanalysis stability,pulsewidth,antennabeamwidth, scan angle, scan rate, and aircraft speed. In addition

  20. Sensitivity of hydro-geomorphic processes to catchment-scale variations in rainfall distribution

    NASA Astrophysics Data System (ADS)

    Valters, Declan; Brocklehurst, Simon; Schultz, David

    2015-04-01

    The dynamics of severe storms have a pronounced effect on the temporal and spatial distribution of water input to river catchments in upland environments, particularly those with complex orography and steep topographic gradients. Existing landscape evolution models typically forsake realistic patterns of rainfall during storm events, in favour of uniform rainfall input. It is demonstrated that this simplification fails to resolve localised areas of flooding and erosion within a drainage basin, despite the known significance of erosion thresholds and orographic enhancement of rainfall. This shortfall can be remedied by the incorporation of high-resolution precipitation data from rainfall radar into model simulations, accounting for sub-catchment-scale variation in precipitation patterns. Using a series of simulations with both synthetic and real topographies, it is shown that there is a wide variation in hydro-geomorphic response observed in comparison to simulations with spatially-averaged rainfall: localised water depths and erosion rates vary by up to an order of magnitude within the catchments studied. The real-data examples, chosen from severe UK rainfall events over the last 10 years, are analysed by combining the CAESAR-Lisflood landscape evolution model at 5m resolution with data from the UK Met Office NIMROD rainfall radar at 1km resolution. The model-coupling framework presented is also suited to using output from weather forecasting models. The applications are wide-ranging, from improving the accuracy of hydrological predictions during single storm events, to understanding longer-term evolution of catchment-scale geomorphology.

  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. Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers (Ligda)

    E-print Network

    Rutledge, Steven

    Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers similar observations in the early 1940's (U.S. Air Corps meteorologists receiving "radar" training at MIT in 1943 First operational weather radar, Panama, 1943 Science of radar meteorology born from WWII research

  3. Spaceborne Doppler Precipitation Radar: System Configurations and Performance Analysis

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Im, Eastwood

    2004-01-01

    Knowledge of the global distribution of the vertical velocity of precipitation is important in in the study of energy transportation in the atmosphere, the climate and weather. Such knowledge can only be directly acquired with the use of spaceborne Doppler precipitation radars. Although the high relative speed of the radar with respect to the rainfall particles introduces significant broadening in the Doppler spectrum, recent studies have shown that the average vertical velocity can be measured to acceptable accuracy levels by appropriate selection of radar parameters. Furthermore, methods to correct for specific errors arising from NUBF effects and pointing uncertainties have recently been developed. In this paper we will present the results of the trade studies on the performances of a spaceborne Doppler radar with different system parameters configurations.

  4. Particle aggregation in volcanic clouds from the 2009 eruption of Redoubt Volcano, Alaska: Observations of Doppler weather radar, satellite images and tephra-fall deposits

    NASA Astrophysics Data System (ADS)

    Schneider, D. J.; Wallace, K. L.; Mastin, L. G.

    2012-12-01

    The combined use of weather radar and thermal infrared satellite images provides complementary evidence that can be used to observe and interpret tephra-fall processes. Radar is ideal for characterizing coarse-grained tephra in the eruption column and proximal cloud, while thermal infrared satellite data are better able to characterize the fine-grained distal volcanic cloud. We present observations of radar, satellite images, and character of the tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska. Accretionary tephra-ice pellets (up to 9 mm in diameter) comprised of fine-grained ash (less than 63 micron diameter) were abundant in the many of the proximal tephra-fall deposits. The eruption column and proximal cloud from seventeen explosive events were observed using the MiniMax-250C (MM-250C) volcano-monitoring Doppler weather radar located 80 km from the vent. Radar reflectivity and radial Doppler velocity measurements were made of the column, every 70-90 seconds at a vertical resolution of about 2 km. Radar reflectivity is highly dependent upon particle size and to a lesser extent, concentration. At 80 km distance, the minimum detectable particle diameter for the MM-250C was about 0.2 mm for a mass concentration of 100 g/m3. Thus, the radar was able to observe the aggregate pellets, and not the fine-grained ash. Most of the explosive events were characterized by high radar reflectivity values of 50-60 dBZ in the central core of the eruption column and proximal cloud, which we interpret to be related to the rapid growth of accretionary tephra-ice pellets. Tephra-fall deposits extended for distances of several hundred kilometers and mapped to a minimum mass density of 10 g/m2. However, the MM-250C radar data were only able to observe the dispersed cloud for tens of kilometers from the source, which was well within the 1000 g/m2 isomass contour. Fine-grained ash was prematurely removed from the eruption cloud in proximal locations due to aggregate formation. The relative lack of fine-grained ash may account for the poor thermal infrared brightness temperature signals observed in satellite images for many of the distal volcanic clouds from the 2009 eruption, and possibly from the 1989-90 eruption as well. Time-series of radial Doppler velocity images documented the transition from turbulent mixing in the column to larger scale entrainment within the proximal cloud. Large scale entrainment begins to develop within minutes of eruption onset. Most of the eruption clouds from the explosive events reached the stratosphere, but the large scale entrainment appears to be better developed in the tropospheric portion of the cloud.

  5. NASA Satellite Reveals Heavy Rainfall Patterns in California

    NSDL National Science Digital Library

    Lori Perkins

    2005-01-12

    The collision of a flow of moisture from Hawaii known as a "Pineapple Express" and a persistent low pressure system are wreaking havoc on California weather. This movie shows rain accumulation in San Diego from Jan. 6 through Jan. 11 based on data from the Tropical Rainfall Measuring Mission (TRMM)-based Multisatellite Precipitation Analysis. The accumulation is shown in colors ranging from green (less than 50 mm of rain) through red (200 mm or more). The TRMM satellite, using the worlds only spaceborne rain radar and other microwave instruments, measures rainfall over the ocean. In this case instruments were able to reveal rainfall structure resulting from storms "riding" the actual Pineapple Express extending toward Hawaii, which is beyond the range of conventional land-based National Weather Service radars. In early 1995, a Pineapple Express hit California, contributing to a season of winter storms that killed 27 people and did $3 billion in damages and costs. A Pineapple Express in mid-October 2003 wreaked havoc from south of Seattle to north of Vancouver Island. Flooding forced more than 3,000 people from their homes.

  6. 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.

    2015-04-01

    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.

  7. 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 ?S cm-1 during periods of high- and low-flow, respectively. Despite the low concentrations in this stream, geochemical relationships were similar to other Amazonian streams draining shield geologies. Discharge-concentration relationships for Ca and Mg in these highly weathered soils developed from igneous rocks of the Brazilian shield demonstrated a significant negative relationship indicating a continued predominance of groundwater baseflow contributions these cationic elements.

  8. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 51, NO. 4, APRIL 2013 2337 Modeling and Prediction of Rainfall Using Radar

    E-print Network

    Kusiak, Andrew

    originating in the watershed basin depends on the amount of rainfall. The Soil and Water Assessment Tool (SWAT to SWAT. The rainfall data enable SWAT to predict water quality [4]. The hydrological and meteorological

  9. Weather Instruments

    NSDL National Science Digital Library

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

  10. 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 radar data providing the NCDC Viewer/Data Exporter the functionality to read C-Band. This also supports a bilateral agreement between the United States and Canada for data sharing and to support interoperability with the US WSR-88D and Environment Canada radar networks. In addition, the NCDC partnered with the University of Oklahoma to develop decoders to read a test bed of distributed X- band radars that are funded through the Collaborative Adaptive Sensing of the Atmosphere (CASA) project. The NCDC is also archiving the National Mosaic and Next Generation QPE (Q2) products from NSSL, which provide products such as three-dimensional reflectivity, composite reflectivity and precipitation estimates at a 1 km resolution. These three sources of Radar data are also supported in the WRT.

  11. Recent findings with rainfall monitoring by cellular communication systems

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  12. 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.

  13. Climate and Weather

    NSDL National Science Digital Library

    National Geographic

    This video discusses the differences between climate and weather by defining and presenting examples of each. When presenting examples of weather, the video focuses on severe events and how meteorologists predict and study the weather using measurement, satellites, and radar. The climate focus is primarily on an overview of climate zones.

  14. Weather and Forecasting Fine-Scale Orographic Precipitation Variability and Gap-Filling Radar Potential in Little

    E-print Network

    Steenburgh, Jim

    Potential in Little Cottonwood Canyon, Utah --Manuscript Draft-- Manuscript Number: WAF-D-13-00129 Full Title: Fine-Scale Orographic Precipitation Variability and Gap-Filling Radar Potential in Little is placed on precipitation features in and around Little Cottonwood Canyon (LCC), which cuts orthogonally

  15. Remote Sensing of Volcanic Ash Cloud During Explosive Eruptions Using Ground-Based Weather RADAR Data Processing [In the Spotlight

    Microsoft Academic Search

    Frank S. Marzano

    2011-01-01

    no activity), and human (ash plume height and shape). Within this list, it should be added the use of groundbased meteorological microwave radars whose new role, within the volcanic ash monitoring network, is the goal of this short contribution. Real-time and aerial monitoring of a volcano eruption, in terms of its intensity and dynamics, is not always possible by conventional

  16. Analysis of 11 june 2003 mesoscale convective vortex genesis using weather surveillance radar ??88 doppler (wsr-88d)

    E-print Network

    Reynolds, Amber Elizabeth

    2009-05-15

    landfalling hurricane and lead to catastrophic flooding. The number of studies using multi-Doppler radar observations for validation of the kinematics, or three-dimensional (3-D) wind structure, of MCV genesis is limited. For this study, the Oklahoma City...

  17. 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 effort is needed in providing suitable predictors for rainfall rather than in optimizing by the choice of the ML algorithm.

  18. Microphysical cross validation of spaceborne radar and ground polarimetric radar

    Microsoft Academic Search

    V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

    2003-01-01

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

  19. Enviropedia: Introduction to Weather

    NSDL National Science Digital Library

    2007-12-12

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

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

    NASA Astrophysics Data System (ADS)

    Vongsaard, Jearanai

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

  1. Comparison of TRMM Precipitation Radar and Airborne Radar Data.

    NASA Astrophysics Data System (ADS)

    Durden, S. L.; Im, E.; Haddad, Z. S.; Li, L.

    2003-06-01

    The first spaceborne weather radar is the precipitation radar (PR) on the Tropical Rainfall Measuring Mission (TRMM), which was launched in 1997. As part of the TRMM calibration and validation effort, an airborne rain-mapping radar (ARMAR) was used to make underflights of TRMM during the B portion of the Texas and Florida Underflights (TEFLUN-B) and the third Convection and Moisture Experiment (CAMEX-3) in 1998 and the Kwajalein Experiment (KWAJEX) in 1999. The TRMM PR and ARMAR both operate at 14 GHz, and both instruments use a downward-looking, cross-track scanning geometry, which allows direct comparison of data. Nearly simultaneous PR and ARMAR data were acquired in seven separate cases. These data are compared to examine the effects of larger resolution volume and lower sensitivity in the PR data relative to ARMAR. The PR and ARMAR data show similar structures, although the PR data tend to have lower maximum reflectivities and path attenuations because of nonuniform beam-filling effects. Nonuniform beam filling can also cause a bias in the observed path attenuation relative to that corresponding to the beam-averaged rain rate. The PR rain-type classification is usually consistent with the ARMAR data.

  2. Stormfax Weather Services

    NSDL National Science Digital Library

    2002-06-10

    This site offers links to a variety of weather information, including national, international and local weather maps and forecasts, satellite and radar imagery, and severe weather warnings. There are also links to diverse resources such as fire maps, glacier inventories, snow depths, storm surges and tropical storms. There are reports and advisories about El Nino and La Nina. The site also has a glossary of weather terms and conversion charts for temperature, wind speed and atmospheric pressure.

  3. 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 weather reports had either an OT detected before a severe weather warning or no warning issued at all. The relationships between satellite OT signatures, severe weather, and heavy rainfall shown in this paper suggest that 1) when an OT is detected, the particular storm is likely producing heavy rainfall and/or possibly severe weather; 2) an objective OT detection product can be used to increase situational awareness and forecaster confidence that a given storm is severe; and 3) this product may be particularly useful in regions with insufficient radar coverage.

  4. 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.

  5. Unisys Weather

    NSDL National Science Digital Library

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

  6. Interactive Weather Information Network

    NSDL National Science Digital Library

    Offered by the National Oceanic and Atmospheric Administration (NOAA), the Interactive Weather Information Network (IWIN) is a collection of interactive weather maps and satellite images that is updated every five seconds. Visitors can see cloud cover animation loops, NEXRAD Radar images of precipitation, a map of all current weather fronts, and an interactive national map to see information about any particular state. Other information on the site includes a listing of any active weather warnings, a link for world weather data, and more, making this a must-see site for all those users interested in the most current weather happenings anywhere.

  7. 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.

  8. 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.

  9. Weather Forecasting

    NSDL National Science Digital Library

    John Nielsen-Gammon

    1996-09-01

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

  10. Doppler Radar Technology

    NSDL National Science Digital Library

    This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

  11. Radar network characterization

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2007-01-01

    The use of dense networks of small radars for weather sensing is being investigated by the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere, with a first test-bed of this new paradigm well underway. The potential benefits of closely-deployed, overlapping, short-range weather radars are easy to see intuitively, and can be summarized as a greater ability to mitigate

  12. Evaluation of the value of radar QPE data and rain gauge data for hydrological modeling

    NASA Astrophysics Data System (ADS)

    He, Xin; Sonnenborg, Torben O.; Refsgaard, Jens Christian; Vejen, Flemming; Jensen, Karsten H.

    2013-09-01

    Weather radar-based quantitative precipitation estimation (QPE) is in principle superior to the areal precipitation estimated by using rain gauge data only, and therefore has become increasingly popular in applications such as hydrological modeling. The present study investigates the potential of using multiannual radar QPE data in coupled surface water—groundwater modeling with emphasis given to the groundwater component. Since the radar QPE is partly dependent on the rain gauge observations, it is necessary to evaluate the impact of rain gauge network density on the quality of the estimated rainfall and subsequently the simulated hydrological responses. A headwater catchment located in western Denmark is chosen as the study site. Two hydrological models are built using the MIKE SHE code, where they have identical model structures expect for the rainfall forcing: one model is based on rain gauge interpolated rainfall, while the other is based on radar QPE which is a combination of both radar and rain gauge information. The two hydrological models are inversely calibrated and then validated against field observations. The model results show that the improvement introduced by using radar QPE data is in fact more obvious to groundwater than to surface water at daily scale. Moreover, substantial negative impact on the simulated hydrological responses is observed due to the cut down in operational rain gauge network between 2006 and 2010. The radar QPE based model demonstrates the added value of the extra information from radar when rain gauge density decreases; however it is not able to sustain the level of model performance preceding the reduction in number of rain gauges.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  14. 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.

  15. Caribbean Radar Cases

    NSDL National Science Digital Library

    2014-09-14

    This module presents radar case studies taken from events in the Caribbean that highlight radar signatures of severe weather. These cases include examples of deep convection, squall lines, bow echoes, tornadoes, and heavy rain resulting in flooding. Each case study includes a discussion of the conceptual models of each type of event as a review before showing the radar signatures and allowing the learner to analyze each one.

  16. WEATHER CONDITIONS IN SOUTH AUSTRALIA Near average rainfall was reported over most of the State; isolated pockets of above average falls were

    E-print Network

    Greenslade, Diana

    extending from Mount Hope to Tumby Bay to Cleve. Most of Kangaroo Island, the southern part of the Lower Lofty Ranges and Kangaroo Island. However, there were rainfall reports from Blackwood, (71mm); Echunga west of the State, the north east of Kangaroo Island, the coastal region of the Lower North district

  17. 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

  18. Everything Weather- Archived Data

    NSDL National Science Digital Library

    2001-01-01

    Users can obtain current weather forecasts for their own areas by entering a ZIP code, or they can access a large archive of historic data on severe weather (tornadoes, hail, high winds, hurricanes). Materials presented in the archive include dates, times, and intensities of storms, a photo gallery, maps, radar and other satellite data, storm chaser reports, and links to other weather sites. Raw data can be found in several forms for teachers wishing to have unprocessed data to work with.

  19. Damage Survey, Radar, and Environment Analyses on the First-Ever Documented Tornado in Beijing during the Heavy Rainfall Event of 21 July 2012

    E-print Network

    Meng, Zhiyong

    Damage Survey, Radar, and Environment Analyses on the First-Ever Documented Tornado in Beijing the most detailed information in all of the published tornado damage surveys so far in China, this work showed significant evidence that the wind damage was caused by a mesocyclonic tornado rated as a category

  20. Rainy Day: A Remote Sensing-Driven Extreme Rainfall Simulation Approach for Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Wright, Daniel; Yatheendradas, Soni; Peters-Lidard, Christa; Kirschbaum, Dalia; Ayalew, Tibebu; Mantilla, Ricardo; Krajewski, Witold

    2015-04-01

    Progress on the assessment of rainfall-driven hazards such as floods and landslides has been hampered by the challenge of characterizing the frequency, intensity, and structure of extreme rainfall at the watershed or hillslope scale. Conventional approaches rely on simplifying assumptions and are strongly dependent on the location, the availability of long-term rain gage measurements, and the subjectivity of the analyst. Regional and global-scale rainfall remote sensing products provide an alternative, but are limited by relatively short (~15-year) observational records. To overcome this, we have coupled these remote sensing products with a space-time resampling framework known as stochastic storm transposition (SST). SST "lengthens" the rainfall record by resampling from a catalog of observed storms from a user-defined region, effectively recreating the regional extreme rainfall hydroclimate. This coupling has been codified in Rainy Day, a Python-based platform for quickly generating large numbers of probabilistic extreme rainfall "scenarios" at any point on the globe. Rainy Day is readily compatible with any gridded rainfall dataset. The user can optionally incorporate regional rain gage or weather radar measurements for bias correction using the Precipitation Uncertainties for Satellite Hydrology (PUSH) framework. Results from Rainy Day using the CMORPH satellite precipitation product are compared with local observations in two examples. The first example is peak discharge estimation in a medium-sized (~4000 square km) watershed in the central United States performed using CUENCAS, a parsimonious physically-based distributed hydrologic model. The second example is rainfall frequency analysis for Saint Lucia, a small volcanic island in the eastern Caribbean that is prone to landslides and flash floods. The distinct rainfall hydroclimates of the two example sites illustrate the flexibility of the approach and its usefulness for hazard analysis in data-poor regions.

  1. 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.

  2. 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.

  3. 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…

  4. The Study of Verification and Correction of Cloud Base and Top Height Retrievals from Ka-band Cloud Radar in Boseong, Korea during Fall 2013

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Oh, S. B.; Kim, K. H.; Cho, C. H.

    2014-12-01

    In this study, the cloud base and top heights observed by Ka-band (33.44 GHz) cloud radar at the Boseong National Center for Intensive Observation of severe weather (NCIO) in Korea during the fall of 2013 (September to November) were verified and corrected. For comparative verification, the base and top heights data obtained from ceilometer (CL51) and Communication, Ocean and Meteorological Satellite (COMS), respectively were used. During rainfall, the cloud base and top heights observed by the cloud radar were lower than that observed by ceilometer-COMS due to signal attenuation and reflectivity caused by raindrops. The stronger rainfall intensity gets, the more the difference grows. In the case of rainfall, the base and top heights data from cloud radar could be replaced with these obtained data from ceilometer-COMS. In the case of no rainfall, the cloud base and top heights observed by the cloud radar and ceilometer-COMS were relatively similar. The clouds with thin thickness or low density were more effectively observed in cloud radar compared to ceilometer-COMS. Based on these results, in case of rainfall or missing cloud radar data, the ceilometer and COMS data were effectively used to correct the cloud radar data. These corrected cloud data were used to classify the cloud types of low (Cloud base height (CBH) < 2 km), middle (2 km ? CBH < 6 km), and high (CBH ? 6 km) clouds, and it was shown that the frequency of occurrence for low clouds were highest. When the low clouds were further subdivided, the most common type was shown to be deep precipitable clouds (CBH < 200 m and Cloud top height (CTH) ? 2 km), followed by non-precipitable clouds (200 m ? CBH < 2 km) and shallow precipitable clouds (CBH < 200 m and CTH < 2 km) in this order.

  5. Spatial-temporal rainfall input resolution requirements for urban drainage modelling: a multi-storm, multi-catchment investigation

    NASA Astrophysics Data System (ADS)

    Ochoa-Rodriguez, Susana; Wang, Li-Pen; Gires, Auguste; Pina, Rui; Reinoso-Rondinel, Ricardo; Bruni, Guendalina; Ichiba, Abdellah; Gaitan, Santiago; Cristiano, Elena; van Assel, Johan; Kroll, Stefan; Murlà-Tuyls, Damian; Schertzer, Daniel; Tchiguirinskaia, Ioulia; Willems, Patrick; Onof, Christian; ten Veldhuis, Marie-Claire

    2015-04-01

    Urban hydrological applications require high resolution precipitation and catchment information in order to well represent the spatial variability, fast runoff processes and short response times of urban catchments. Although fast progress has been made over the last few decades in high resolution measurement of rainfall at urban scales, including increasing use of weather radars, the resolution of the currently available rainfall estimates (typically 1 x 1 km2 in space and 5 min in time) may still be too coarse to meet the stringent spatial-temporal scales characteristic of urban catchments. In addition, current evidence is still insufficient to provide a concrete answer regarding rainfall input resolution requirements of urban hydrological applications. With the aim of providing further evidence in this regard, in the framework of the EU Interreg RainGain project a collaborative study was conducted which investigated the impact of rainfall estimates for a range of spatial and temporal resolution combinations on the outputs of operational semi distributed models of seven urban catchments in North-West Europe. Nine storm events measured by a dual polarimetric X-band weather radar, located in the Cabauw Experimental Site for Atmospheric Research (CESAR) of the Netherlands, were selected for analysis. Based on the original radar estimates, at 100 m and 1 min resolutions, 15 different combinations of coarser spatial and temporal resolutions, up to 3000 m and 10 min, were generated. These estimates were applied to the hydraulic models of the urban catchments, all of which have similar size (between 3 and 8 km2), but different morphological, hydrological and hydraulic characteristics. When doing so, methodologies for standardising model outputs and making results comparable were implemented. Results were analysed in the light of storm and catchment characteristics. Three main features were observed in the results: (1) the impact of rainfall input resolution decreases as catchment drainage area increases; (2) in general, the variation in temporal resolution of rainfall inputs affects hydrodynamic model results more strongly than variations in spatial resolution; (3) there is a strong interaction between the spatial and temporal resolution of rainfall input estimates and in order to avoid losing relevant information from the rainfall fields, the two resolutions must be in agreement with each other. Based on these results, initial models to quantify the impact of rainfall input resolution as a function of catchment size and spatial-temporal characteristics of storms are proposed and discussed.

  6. Regional extreme rainfalls observed globally with 17 years of the Tropical Precipitation Measurement Mission

    NASA Astrophysics Data System (ADS)

    Takayabu, Yukari; Hamada, Atsushi; Mori, Yuki; Murayama, Yuki; Liu, Chuntao; Zipser, Edward

    2015-04-01

    While extreme rainfall has a huge impact upon human society, the characteristics of the extreme precipitation vary from region to region. Seventeen years of three dimensional precipitation measurements from the space-borne precipitation radar equipped with the Tropical Precipitation Measurement Mission satellite enabled us to describe the characteristics of regional extreme precipitation globally. Extreme rainfall statistics are based on rainfall events defined as a set of contiguous PR rainy pixels. Regional extreme rainfall events are defined as those in which maximum near-surface rainfall rates are higher than the corresponding 99.9th percentile in each 2.5degree x2.5degree horizontal resolution grid. First, regional extreme rainfall is characterized in terms of its intensity and event size. Regions of ''intense and extensive'' extreme rainfall are found mainly over oceans near coastal areas and are likely associated with tropical cyclones and convective systems associated with the establishment of monsoons. Regions of ''intense but less extensive'' extreme rainfall are distributed widely over land and maritime continents, probably related to afternoon showers and mesoscale convective systems. Regions of ''extensive but less intense'' extreme rainfall are found almost exclusively over oceans, likely associated with well-organized mesoscale convective systems and extratropical cyclones. Secondly, regional extremes in terms of surface rainfall intensity and those in terms of convection height are compared. Conventionally, extremely tall convection is considered to contribute the largest to the intense rainfall. Comparing probability density functions (PDFs) of 99th percentiles in terms of the near surface rainfall intensity in each regional grid and those in terms of the 40dBZ echo top heights, it is found that heaviest precipitation in the region is not associated with tallest systems, but rather with systems with moderate heights. Interestingly, this separation of extremely heavy precipitation from extremely tall convection is found to be quite universal, irrespective of regions. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Thus it is demonstrated that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. Third, the size effect of rainfall events on the precipitation intensity is investigated. Comparisons of normalized PDFs of foot-print size rainfall intensity for different sizes of rainfall events show that footprint-scale extreme rainfall becomes stronger as the rainfall events get larger. At the same time, stratiform ratio in area as well as in rainfall amount increases with the size, confirming larger sized features are more organized systems. After all, it is statistically shown that organization of precipitation not only brings about an increase in extreme volumetric rainfall but also an increase in probability of the satellite footprint scale extreme rainfall.

  7. Machine learning methods for the classification of extreme rainfall and hail events

    NASA Astrophysics Data System (ADS)

    Teschl, Reinhard; Süsser-Rechberger, Barbara; Paulitsch, Helmut

    2015-04-01

    In this study, an analysis of a meteorological data set with machine learning tools is presented. The aim was to identify characteristic patterns in different sources of remote sensing data that are associated with hazards like extreme rainfall and hail. The data set originates from a project that was started in 2007 with the goal to document and mitigate hail events in the province of Styria, Austria. It consists of three dimensional weather radar data from a C-band Doppler radar, cloud top temperature information from infrared channels of a weather satellite, as well as the height of the 0° C isotherm from the forecast of the national weather service. The 3D radar dataset has a spatial resolution of 1 km x 1 km x 1 km, up to a height of 16 km above mean sea level, and a temporal resolution of 5 minutes. The infrared satellite image resolution is about 3 km x 3 km, the images are updated every 30 minutes. The study area has approx. 16,000 square kilometers. So far, different criteria for the occurrence of hail (and its discrimination from heavy rain) have been found and are documented in the literature. When applying these criteria to our data and contrasting them with damage reports from an insurance company, a need for adaption was identified. Here we are using supervised learning paradigms to find tailored relationships for the study area, validated by a sub-dataset that was not involved in the training process.

  8. Total rainfall and convective rainfall in Catalonia, Spain

    NASA Astrophysics Data System (ADS)

    Llasat, M. C.; Puigcerver, M.

    1997-12-01

    A substantial percentage of the total rainfall amount in Catalonia (north-east of Spain) stems from convective cloud systems. To obtain a quantitative estimate, convective events were identified on the charts of a rain-rate recorder from 1960 to 1979. Events were classified into four categories: non-convective, convective with low rainfall rates, convective with moderate to high rates and thunderstorm events. The amount of rain due to each of these was computed. The ratio of convective to total rainfall amounts ranges from 70 to 80 per cent in the summer months to less than 30 per cent in winter and its pattern through the year is discussed as regards regional weather and climate. Orographical features, potential instability of the atmosphere and high sea-surface temperatures are related to high-rate events. The uncertain character of rainfall in the area is clearly linked to the large share of convective rainfall on the bulk precipitation.

  9. Convective rain cell modelling from radar data and their linking with a hydrological model

    NASA Astrophysics Data System (ADS)

    Morin, E.; Yakir, H.

    2009-04-01

    The technology of weather radar systems enables a detailed view of rainstorms over watersheds with high spatial and temporal resolution that was never available before. Nevertheless, the utilization of radar rainfall data in hydrological models has not brought a significant improvement in understanding rainfall-runoff processes, and in prediction capability of watershed responses. There is a need to develop new ways to exploit essential information about spatio-temporal rain structures, and gain greater insights into rainfall and subsequent watershed response behavior. The current study suggests an innovative approach to the above challenge. We emphasize as a key issue the structure in which the data are represented in the hydrological models. Whereas in the standard approach, radar data are utilized in a grid structure, we propose to represent the rainfall data in a model-structure that takes into account the known behavior and properties of the rain system. The spatial and temporal characteristics of the rain system are thus explicitly represented and are linked directly to hydrological responses. The basic distinction between the grid and the currently suggested data model-structures is the presence of a-priori knowledge about the represented system incorporated into the model. The above approach was applied in the analysis of a large flood event in a semi-arid catchment in southern Israel. A model representing the spatio-temporal structure of the derived rain cells was developed and fitted to the radar data. The hydrological model was then fed by the rain cell information rather than the gridded radar data. Using this direct linkage between rain cell features and hydrological features the main controls of the generated flood were determined.

  10. Use of dual-frequency microwave links for measuring path-averaged rainfall

    NASA Astrophysics Data System (ADS)

    Rahimi, A. R.; Holt, A. R.; Upton, G. J. G.; Cummings, R. J.

    2003-08-01

    Results are presented from an experiment designed to test the use of dual-frequency microwave attenuation for measuring path-averaged rainfall. In general, the relation between attenuation and path-averaged rainfall is nonlinear. However, for carefully chosen pairs of frequencies, the relation between the difference in attenuations and path-averaged rainfall is well represented by a straight line through the origin. The slope of this line is essentially unaffected by variations in the (unknown) drop size distribution, drop shape, and drop temperature. This paper describes the results obtained from a pair of links operating at 12.8 GHz and 17.6 GHz on a 23.3 km path. Results are shown for three individual events, including comparisons with rainfall estimates obtained from more traditional sources: a local rain gauge network and an adjacent weather radar. We report summary results for 112 events recorded on this path during almost 2 years of observation, and also for 52 events recorded on a nearby 13.9 km path operating at 13.9 GHz and 22.9 GHz. In both cases the results suggest that dual-frequency links could serve as useful additional tools for the measurement of rainfall, particularly in locations such as urban areas and obscured mountain valleys, where traditional measuring instruments struggle to provide accurate estimates.

  11. 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.

  12. 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 diabatic heating during the early stages of a forecast period. This procedure is expected to enhance details in the moisture field during model integration, and thus improve spinup performance, assuming the errors in the future time latent heating data ate less than intrinsic model background errors.

  13. TRMM Precipitation Radar Reflectivity Profiles as Compared with High-Resolution Airborne and Ground-Based Radar Measurements

    Microsoft Academic Search

    G. M. Heymsfield; B. Geerts; L. Tian

    2000-01-01

    Orbital Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) products are evaluated by simultaneous comparisons with high-resolution data from the high-altitude ER-2 Doppler radar (EDOP) and ground-based radars. The purpose is not to calibrate any radar or to validate surface rainfall estimates, but rather to evaluate the vertical reflectivity structure, which is important in TRMM rain-type classification and estimation of

  14. 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 precipitation estimates. J. Appl. Meteor., 39(10), 1715-1726.

  15. Weather Depot 1.21

    NSDL National Science Digital Library

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

  16. Range adjustment for ground-based radar, derived with the spaceborne TRMM precipitation radar

    Microsoft Academic Search

    Marco Gabella; Jürg Joss; Giovanni Perona; Silas Michaelides

    2006-01-01

    We show how the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (TPR) can be used to monitor and adjust ground-based radar (GR) data, as a function of the distance from the radar site. Problems caused by the variability of precipitation and differences in sampling volume of the two instruments are reduced to a level that is achievable with, and acceptable

  17. Radar cross-section of Earth surfaces measured by spaceborne precipitation radar (TRMM PR)

    Microsoft Academic Search

    M. Satake; H. Hanado; T. Kozu

    2000-01-01

    Normalized radar cross section of Earth's surfaces are investigated using surface reflectivity data measured by a spaceborne radar, the Precipitation Radar boarded on the Tropical Rainfall Measuring Mission (TRMM PR). Homogeneous surfaces larger than 220 km of the PR's observation swath are selected for the investigation site, including rain forests, oceans, and some land areas. `Surface Sigma-O' products of the

  18. Geostatistical merging of rain gauge and radar data for high temporal resolutions and various station density scenarios

    NASA Astrophysics Data System (ADS)

    Berndt, Christian; Rabiei, Ehsan; Haberlandt, Uwe

    2014-01-01

    Three merging methods for high resolution radar and gauge rainfall were compared.Effect of station density, temporal resolution and radar data smoothing was analyzed.Radar data smoothing improved the interpolation performance significantly.Conditional merging performed best for all station densities and temp. resolutions.Radar rainfall quality has a strong impact on the merging performance.

  19. Validation of TRMM Precipitation Radar Through Comparison of its Multi-Year Measurements to Ground-Based Radar

    NASA Technical Reports Server (NTRS)

    Liao, Liang; Meneghini, Robert

    2010-01-01

    A procedure to accurately resample spaceborne and ground-based radar data is described, and then applied to the measurements taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and the ground-based Weather Surveillance Radar-1988 Doppler (WSR-88D or WSR) for the validation of the PR measurements and estimates. Through comparisons with the well-calibrated, non-attenuated WSR at Melbourne, Florida for the period 1998-2007, the calibration of the Precipitation Radar (PR) aboard the TRMM satellite is checked using measurements near the storm top. Analysis of the results indicates that the PR, after taking into account differences in radar reflectivity factors between the PR and WSR, has a small positive bias of 0.8 dB relative to the WSR, implying a soundness of the PR calibration in view of the uncertainties involved in the comparisons. Comparisons between the PR and WSR reflectivities are also made near the surface for evaluation of the attenuation-correction procedures used in the PR algorithms. It is found that the PR attenuation is accurately corrected in stratiform rain but is underestimated in convective rain, particularly in heavy rain. Tests of the PR estimates of rainfall rate are conducted through comparisons in the overlap area between the TRMM overpass and WSR scan. Analyses of the data are made both on a conditional basis, in which the instantaneous rain rates are compared only at those pixels where both the PR and WSR detect rain, and an unconditional basis, in which the area-averaged rain rates are estimated independently for the PR and WSR. Results of the conditional rain comparisons show that the PR-derived rain is about 9% greater and 19% less than the WSR estimates for stratiform and convective storms, respectively. Overall, the PR tends to underestimate the conditional mean rain rate by 8% for all rain categories, a finding that conforms to the results of the area-averaged rain (unconditional) comparisons.

  20. The potential of cellular network infrastructures for sudden rainfall monitoring in dry climate regions

    NASA Astrophysics Data System (ADS)

    David, N.; Alpert, P.; Messer, H.

    2013-09-01

    Monitoring of precipitation and in particular sudden rain, in rural dry climate regions, is a subject of great significance in several weather related processes such as soil erosion, flash flooding, triggering epidemics and more. The rainfall monitoring facilities in these regions and as a result precipitation data are, however, commonly, severely lacking. As was recently shown, cellular networks infrastructures supply high resolution precipitation measurements at ground level while often being situated in dry areas, covering large parts of these climatic zones. The potential found in these systems to provide early monitoring and essential precipitation information, directly from arid regions, based on standard measurements of commercial microwave links, is exemplified here over the Negev and the Southern Judean desert, South Israel. We present the results of two different rainfall events occurred in these regions. It is shown that the microwave system measured precipitation between at least 50 min (in case 1) and at least 1 h and 40 min (in case 2) before each of the sparse rain gauges. During each case, the radar system, located relatively far from the arid sites, provided measurements from heights of at least 1500 m and 2000 m above surface, respectively. A third case study demonstrates a relative advantage of microwave links to measure precipitation intensity with respect to the radar system, over an area of complex topography located in northeastern Israel, which is relatively far (~ 150 km) from the radar.

  1. Evaluating the use of high-resolution numerical weather forecast for debris flow prediction.

    NASA Astrophysics Data System (ADS)

    Nikolopoulos, Efthymios I.; Bartsotas, Nikolaos S.; Borga, Marco; Kallos, George

    2015-04-01

    The sudden occurrence combined with the high destructive power of debris flows pose a significant threat to human life and infrastructures. Therefore, developing early warning procedures for the mitigation of debris flows risk is of great economical and societal importance. Given that rainfall is the predominant factor controlling debris flow triggering, it is indisputable that development of effective debris flows warning procedures requires accurate knowledge of the properties (e.g. duration, intensity) of the triggering rainfall. Moreover, efficient and timely response of emergency operations depends highly on the lead-time provided by the warning systems. Currently, the majority of early warning systems for debris flows are based on nowcasting procedures. While the latter may be successful in predicting the hazard, they provide warnings with a relatively short lead-time (~6h). Increasing the lead-time is necessary in order to improve the pre-incident operations and communication of the emergency, thus coupling warning systems with weather forecasting is essential for advancing early warning procedures. In this work we evaluate the potential of using high-resolution (1km) rainfall fields forecasted with a state-of-the-art numerical weather prediction model (RAMS/ICLAMS), in order to predict the occurrence of debris flows. Analysis is focused over the Upper Adige region, Northeast Italy, an area where debris flows are frequent. Seven storm events that generated a large number (>80) of debris flows during the period 2007-2012 are analyzed. Radar-based rainfall estimates, available from the operational C-band radar located at Mt Macaion, are used as the reference to evaluate the forecasted rainfall fields. Evaluation is mainly focused on assessing the error in forecasted rainfall properties (magnitude, duration) and the correlation in space and time with the reference field. Results show that the forecasted rainfall fields captured very well the magnitude and dynamics of rainfall in most of the cases, which reveals a great potential in using high-resolution weather forecast for advancing debris flow warning systems.

  2. Evaluation of the QPF of convective flash flood rainfalls over the Czech territory in 2009

    NASA Astrophysics Data System (ADS)

    Zacharov, Petr; Rezacova, Daniela; Brozkova, Radmila

    2013-09-01

    In this paper, quantitative precipitation forecasts (QPF) are evaluated using several verification techniques and analysis of the results from these techniques. The forecasts were produced by two limited-area numerical weather prediction models: the ALADIN-CZ model operated by the Czech Hydro-Meteorological Institute (CHMI) and the COSMO model operated by the German Weather Service (DWD). Each model was run using two horizontal resolutions over the domain covering the Czech Republic. The ALADIN-CZ model outputs were obtained using resolutions of approximately 9 km and 4.7 km, and the COSMO model outputs were obtained using resolutions of approximately 7 km and 2.8 km. The forecast quality is studied for the flash flood period that occurred in June and July of 2009, when convective rainfalls with durations of 1 to 3 h and a return period of more than 100 years caused devastating floods in many Czech localities. The radar-based rainfalls used to verify the forecasts were produced by the CHMI operational product MERGE, which merges radar-derived rainfalls with the rainfalls that are measured by ground rain gauges. A series of 56 consecutive forecasts of 3-h rainfalls were verified using traditional and spatial verification techniques, and the results from these analyses were compared. The verification was performed using traditional verification scores based on a contingency table, spatial verification by the fractions skill score (FSS) and the SAL (structure-amplitude-location) technique. The FSS represents a fuzzy verification technique and compares the fractional coverage of precipitation grids over a threshold in spatial windows around the observations and forecasts. The SAL is a spatial object-oriented verification technique used to evaluate the structure, amplitude, and location of a precipitation field. The quality of QPF depends strongly on the scale of convective precipitation, and all models provide good forecast quality for extended rainfall systems. The opposite is true for the local and more or less chaotic convection during the final part of the time period. The FSS indicates how the results depend on the threshold and scale of precipitation. The COSMO 2.8 model is able to determine the largest local rainfall values, but models with lower resolution, such as the ALADIN 9 km and COSMO 7 km, provide better results for lower thresholds and larger scales. The use of more verification techniques is suitable for a modeller-oriented evaluation of different aspects of forecast quality.

  3. Ground truth observations for TRMM. [Tropical Rainfall Measuring Mission

    NASA Technical Reports Server (NTRS)

    Thiele, Otto W.

    1989-01-01

    Plans to obtain ground truth data for the validation of the Tropical Rainfall Measuring Mission (TRMM) are examined. The experimental rainfall measuring techniques considered for the program are discussed, including optical and Doppler rain gages, satellite beacon attenuation, underwater hydrophones, profilers, microwave attenuation, multiple frequency/polarization radar, and scanning and airborne Doppler radar. The TRMM validation program is considered, noting observations to compare averaged TRMM rainfall data with similar ground truth data and to compare the rainfall and height distribution data from TRMM with instantaneous ground truth data.

  4. Signal processing technique for removal of NUBF-induced error in spaceborne Doppler precipitation radar measurements

    NASA Astrophysics Data System (ADS)

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

    2002-02-01

    A sampling strategy and a signal processing technique are proposed to overcome Non Uniform Beam Filling (NUBF) errors on mean Doppler velocity measurements made by spaceborne weather radars. Effects of non uniformity of rainfall within the main antenna lobe in terms on the accuracy of standard estimators are first briefly shown, so as to point out that the bias introduced by NUBF on mean Doppler velocity estimates can be greater than the standard deviation of the estimated velocity, and that it depends on the along-track distribution of reflectivity. Then the sampling strategy is described, based on an oversampling of the integrated data in the along-track direction in order to retrieve information about the reflectivity pattern at the sub-beam scale. The proposed processing technique, named Combined Frequency-Time (CFT) technique, exploits the time series of spectra at fixed range to resolve the NUBF induced bias. The results and the evaluation of performances achievable by means of CFT, were obtained by applying a 3D spaceborne Doppler radar simulator to a 3D dataset of reflectivity and mean Doppler velocity measured through the NASA/JPL airborne Doppler radar ARMAR. The radar system considered here is a nadir-looking, Ku band radar with a sufficiently wide antenna. It is shown how the error on mean Doppler velocity estimates can be reduced by means of CFT to the level predicted for such a radar system in the case of uniformly filled resolution volume (UBF).

  5. Optimal combining of ground-based sensors for the purpose of validating satellite-based rainfall estimates

    NASA Technical Reports Server (NTRS)

    Krajewski, Witold F.; Rexroth, David T.; Kiriaki, Kiriakie

    1991-01-01

    Two problems related to radar rainfall estimation are described. The first part is a description of a preliminary data analysis for the purpose of statistical estimation of rainfall from multiple (radar and raingage) sensors. Raingage, radar, and joint radar-raingage estimation is described, and some results are given. Statistical parameters of rainfall spatial dependence are calculated and discussed in the context of optimal estimation. Quality control of radar data is also described. The second part describes radar scattering by ellipsoidal raindrops. An analytical solution is derived for the Rayleigh scattering regime. Single and volume scattering are presented. Comparison calculations with the known results for spheres and oblate spheroids are shown.

  6. Radar Technology Applied to Air Traffic Control

    Microsoft Academic Search

    WILLIAM W. SHRADER

    1973-01-01

    Use of primary radars for air traffic control (ATC) is discussed. The location and the parameters of various ATC radars are described. The clutter environment (land clutter, birds, automobiles, and weather) has had a major impact on the configuration of these radars. Signal-processing techniques and antenna techniques utilized to cope with the clutter are described. Future signal-processing techniques for the

  7. Dual-use air traffic control radar

    Microsoft Academic Search

    Lewis Buckler

    1998-01-01

    During the past seven years the Federal Aviation Administration has had a research program called the Terminal Area Surveillance System (TASS) to develop the next generation airport surveillance radar. At present the FAA has two radars for aircraft and weather surveillance at the major airports. One of these radars, the ASR-9, is for aircraft surveillance and rain intensity. The other,

  8. Systems and methods for supplemental weather information presentation on a display

    NASA Technical Reports Server (NTRS)

    Bunch, Brian (Inventor)

    2010-01-01

    An embodiment of the supplemental weather display system presents supplemental weather information on a display in a craft. An exemplary embodiment receives the supplemental weather information from a remote source, determines a location of the supplemental weather information relative to the craft, receives weather information from an on-board radar system, and integrates the supplemental weather information with the weather information received from the on-board radar system.

  9. 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 where WRF-Hydro reduced mean root mean squared error from 8.31 m3/s to 6.51 m3/s.

  10. Adjusting Satellite Rainfall Error in Mountainous Areas for Flood Modeling Applications

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Anagnostou, E. N.; Astitha, M.; Vergara, H. J.; Gourley, J. J.; Hong, Y.

    2014-12-01

    This study aims to investigate the use of high-resolution Numerical Weather Prediction (NWP) for evaluating biases of satellite rainfall estimates of flood-inducing storms in mountainous areas and associated improvements in flood modeling. Satellite-retrieved precipitation has been considered as a feasible data source for global-scale flood modeling, given that satellite has the spatial coverage advantage over in situ (rain gauges and radar) observations particularly over mountainous areas. However, orographically induced heavy precipitation events tend to be underestimated and spatially smoothed by satellite products, which error propagates non-linearly in flood simulations.We apply a recently developed retrieval error and resolution effect correction method (Zhang et al. 2013*) on the NOAA Climate Prediction Center morphing technique (CMORPH) product based on NWP analysis (or forecasting in the case of real-time satellite products). The NWP rainfall is derived from the Weather Research and Forecasting Model (WRF) set up with high spatial resolution (1-2 km) and explicit treatment of precipitation microphysics.In this study we will show results on NWP-adjusted CMORPH rain rates based on tropical cyclones and a convective precipitation event measured during NASA's IPHEX experiment in the South Appalachian region. We will use hydrologic simulations over different basins in the region to evaluate propagation of bias correction in flood simulations. We show that the adjustment reduced the underestimation of high rain rates thus moderating the strong rainfall magnitude dependence of CMORPH rainfall bias, which results in significant improvement in flood peak simulations. Further study over Blue Nile Basin (western Ethiopia) will be investigated and included in the presentation. *Zhang, X. et al. 2013: Using NWP Simulations in Satellite Rainfall Estimation of Heavy Precipitation Events over Mountainous Areas. J. Hydrometeor, 14, 1844-1858.

  11. THE WEATHER AND CLIMATE TOOLKIT

    Microsoft Academic Search

    Steve Ansari; Chad Hutchins; Stephen Del Greco; Mark Phillips

    The Weather and Climate Toolkit (WCT) is free, platform independent software distributed from NOAA's National Climatic Data Center (NCDC). The WCT allows the visualization and data export of weather and climate data, including NEXRAD Radar, GOES Satellite, NOMADS Model and surface in-situ data. By leveraging the NetCDF for Java library and Common Data Model, the WCT is extremely scalable and

  12. Biases of rain retrieval algorithms for spaceborne radar caused by nonuniformity of rain

    Microsoft Academic Search

    Kenji Nakamura

    1991-01-01

    The biases of various rain retrieval algorithms for a spaceborne rain radar due to nonuniformity of rain are studied using simple models and an actual time sequence of rainfall rate. A conventional rain retrieval algorithm in which measured radar reflectivity factors are simply converted to rainfall rates always overestimates the rainfall rate, but the bias is moderate. The surface reference

  13. Technologies for the next generation of spaceborne precipitation radars

    Microsoft Academic Search

    G. Sadowy; A. Berkun; S. Durden; J. Huang; E. Im; B. Lopez; M. Lou; Y. Rahmat-Samii; Fan-Yun Liu; S. Rengarajan

    2001-01-01

    The precipitation radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) has demonstrated the feasibility of measuring rainfall from space. A concept for the next step, the Second Generation Precipitation Radar (PR-2), has been developed. The PR-2 will yield improved capabilities and substantially reduced system mass compared to the TRMM PR. However, implementation of the PR-2 concept depends upon the

  14. Clutter mitigation using auxiliary elements for the NWRT phased array radar

    Microsoft Academic Search

    K. D. Le; R. D. Palmer; B. L. Cheong; T. Y. Yu; G. Zhang; S. M. Torres

    2008-01-01

    The national weather radar testbed (NWRT) has a 10-cm phased array radar that is used primarily for monitoring the weather. It is attractive compared to the current parabolic dish weather surveillance radar-88 Doppler (WSR-88D) because of its capability to electronically steer. When combined with the recently developed beam multiplexing technique that uses a small number of contiguous samples and clever

  15. SHORT-WAVELENGTH TECHNOLOGY AND THE POTENTIAL FOR DISTRIBUTED NETWORKS OF SMALL RADAR SYSTEMS

    E-print Network

    Droegemeier, Kelvin K.

    apart, these networks defeat the earth curvature blockage that limits today's long-range weather radars;Capsule Summary A new weather radar concept based on dense networks of small radars defeats the earth curvature blockage that limits today's large radars while simultaneously meeting the disparate data needs

  16. Winter Storms Weather Quizzes

    E-print Network

    and report more exact measurements. As it comes closer to land, special weather radars track the hurricane, the sea may rise as high as 25 feet above normal high tide! That is taller than six kids standing on each up all the small things laying around your yard, like toys, tools and flower pots and bring them

  17. Bistatic synthetic aperture radar

    Microsoft Academic Search

    A. M. Horne; G. Yates

    2002-01-01

    Synthetic aperture radar (SAR) is becoming increasingly important in many military ground surveillance and targeting roles because of its ability to operate in all weather, day and night, and to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and receiver are on separate platforms, is seen as a potential means of countering vulnerability. This

  18. Graphical tools for TV weather presentation

    Microsoft Academic Search

    M. Najman

    2010-01-01

    Contemporary meteorology and its media presentation faces in my opinion following key tasks: - Delivering the meteorological information to the end user\\/spectator in understandable and modern fashion, which follows industry standard of video output (HD, 16:9) - Besides weather icons show also the outputs of numerical weather prediction models, climatological data, satellite and radar images, observed weather as actual as

  19. Radar Images of the Earth: Volcanoes

    NSDL National Science Digital Library

    This site features links to thirty-five NASA radar images of the world's volcanoes, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

  20. Diurnal Land Sea Rainfall Peak Migration over Sumatera Island, Indonesian Maritime Continent, Observed by TRMM Satellite and Intensive Rawinsonde Soundings

    Microsoft Academic Search

    Shuichi Mori; Hamada Jun-Ichi; Yudi Iman Tauhid; Manabu D. Yamanaka; Noriko Okamoto; Fumie Murata; Namiko Sakurai; Hiroyuki Hashiguchi; Tien Sribimawati

    2004-01-01

    The diurnal cycle of rainfall and its regional variation over Sumatera Island, Indonesian Maritime Continent, are examined using Tropical Rainfall Measuring Mission (TRMM) satellite precipitation radar (PR) and intensive rawinsonde sounding data. The TRMM PR sensor can detect raindrops directly, regardless of ground and cloud conditions, and can distinguish between convective and stratiform types of rainfall. Rainfall variation over this

  1. Washington Post Weather

    NSDL National Science Digital Library

    The Washington Post makes a bid for the already crowded Internet weather market with WeatherPost. Coverage includes current conditions and four-day forecasts for 3,600 cities worldwide, as well as snapshot and time-lapse satellite maps (provided by Accu Weather). For US cities, users may also access UV and air quality maps and data, as well as seasonal maps (snow cover, tanning index, heat index, and BeachCast) and other radar images such as precipitation. Users may enter a city name into the homepage search box, or may browse by country or state/province. The historical weather database offers compiled monthly average weather data for nearly 1,000 cities worldwide; the database is searchable. An aspect of the site that sets it apart from many other weather pages is the weather reference desk, which includes a weather glossary, weather calculators (JavaScript converters for temperature, wind chill, heat index, etc.) and a page devoted to storm chasers.

  2. Precipitation type determination from spaceborne radar observations

    Microsoft Academic Search

    V. Chandrasekar; Basim Zafar

    2004-01-01

    The Tropical Rainfall Measuring Mission (TRMM) program is dedicated to observing and understanding the impact of tropical rainfall. Two important products of the TRMM precipitation radar include the classification of precipitation into convective and stratiform type as well as determination of the height of the brightband. Currently, TRMM uses an algorithm to arrive at these products based on a characterization

  3. How are Rainfall Rates Measured?

    NSDL National Science Digital Library

    2012-08-03

    In this problem-based learning activity, students learn about weather forecasting and the role of the TRMM (Tropical Rainfall Measuring Mission) satellite in data collection. Assuming the role of climatologists, students assist a reporter in determining the accuracy of weather predictions published in The Old Farmer's Almanac. The lesson requires a street map of the local community, acetate sheets to cover the map, materials needed to build a homemade rain gauge, and sample pages of the almanac. Teacher notes, student worksheet, glossary and an appendix introducing problem-based learning are included. This resource is the first of the 3-part learning module, Investigating the Climate System: Precipitation.

  4. WetNet: Using SSM/I data interactively for global distribution of rainfall and precipitable water

    NASA Technical Reports Server (NTRS)

    Zipser, Edward J.; Mcguirk, James P.

    1991-01-01

    By completing hardware installation, preparing for comparative studies of SSM/I, radar, and lightning data, it is believed that this will be a powerful combination for evaluating the global distribution of tropical rainfall, and the vertical distribution of latent heating, with strong application to algorithms for use on TRMM, EOS-A, and future GOES spacecraft. Potential data bases will be surveyed, about 5 case studies with surface rainfall, radar, lightning, and sounding data will be identified. SSM/I algorithms will be used to identify convective regions of MCSs. A catalog will be developed of the global profile of heavy tropical rainfall, and how these zones are organized within larger tropical weather systems. Beginning with the first few months of SSM/I data distributed over WetNet, SSM/I radiances will be compared with TOVS radiance (moisture and thermal) and OLR observations. The purpose is to improve understanding of how real world water vapor profiles in the tropical atmosphere are perceived by SSM/I precipitable water algorithm and, at the same time, by the TOVS water vapor channel.

  5. Using ensemble rainfall predictions in a countrywide flood forecasting model in Scotland

    NASA Astrophysics Data System (ADS)

    Cranston, M. D.; Maxey, R.; Tavendale, A. C. W.; Buchanan, P.

    2012-04-01

    Improving flood predictions for all sources of flooding is at the centre of flood risk management policy in Scotland. With the introduction of the Flood Risk Management (Scotland) Act providing a new statutory basis for SEPA's flood warning responsibilities, the pressures on delivering hydrological science developments in support of this legislation has increased. Specifically, flood forecasting capabilities need to develop in support of the need to reduce the impact of flooding through the provision of actively disseminated, reliable and timely flood warnings. Flood forecasting in Scotland has developed significantly in recent years (Cranston and Tavendale, 2012). The development of hydrological models to predict flooding at a catchment scale has relied upon the application of rainfall runoff models utilising raingauge, radar and quantitative precipitation forecasts in the short lead time (less than 6 hours). Single or deterministic forecasts based on highly uncertain rainfall predictions have led to the greatest operational difficulties when communicating flood risk with emergency responders, therefore the emergence of probability-based estimates offers the greatest opportunity for managing uncertain predictions. This paper presents operational application of a physical-conceptual distributed hydrological model on a countrywide basis across Scotland. Developed by CEH Wallingford for SEPA in 2011, Grid-to-Grid (G2G) principally runs in deterministic mode and employs radar and raingauge estimates of rainfall together with weather model predictions to produce forecast river flows, as gridded time-series at a resolution of 1km and for up to 5 days ahead (Cranston, et al., 2012). However the G2G model is now being run operationally using ensemble predictions of rainfall from the MOGREPS-R system to provide probabilistic flood forecasts. By presenting a range of flood predictions on a national scale through this approach, hydrologists are now able to consider an objective measure of the likelihood of flooding impacts to help with risk based emergency communication.

  6. Rainfall evaluation by remote sensing: problems and prospects

    Microsoft Academic Search

    ERIC C. BARRETT

    1983-01-01

    The use of radar for precipitation research has a history of over 30 years, and of satellites more than 15 years. Much progress has been made through studies designed to understand better both the nature and distribution of rainfall , and the related characteristics of the radar and satellite data themselves. However, difficult problems remain to be solved before either

  7. Convective rain cells: radar-derived spatio-temporal characteristics and synoptic patterns

    NASA Astrophysics Data System (ADS)

    Peleg, N.; Morin, E.

    2012-04-01

    In this study we present the spatiotemporal characteristics of convective rain cells over the Eastern Mediterranean (northern Israel) and their relationship to synoptic patterns. Information on rain cell features was extracted from high-resolution weather radar data for a total of 191,586 radar volume scans from 12 hydrological years. The convective rain cell features (i.e., cell area, rainfall intensity and cell orientation) were obtained using cell segmentation technique. Cell tracking algorithm was used to analyze the changes of those features over time. Convective rain cells were clustered into three synoptic types (two extratropical winter lows: deep Cyprus low and shallow low, and a tropical intrusion: Active Red Sea Trough) using several NCEP/NCAR parameters, and empirical distributions were computed for their spatial and temporal features. In the study region, it was found that the Active Red Sea Trough rain cells are larger, live for less time and possess lower rain intensities than the rain cells generated by the winter lows. The Cyprus low rain cells were found to be less intense and slightly larger on average than the shallow low rain cells. It was further discovered that the preferential orientation of the rain cells is associated with the direction and velocity of the wind. The effect of distance from the coastline was also examined. An increase in the number and area of the rain cells near the coastline was observed, presumably due to the sea breeze convection. The mean rainfall intensity was found to peak near the shore and decrease with distance inland. This information is of great importance for understanding rain patterns and can be further applied in exploring the hydrological responses of the basins in this region. The presented study is the first step in achieving the long-term goal: to develop a high space-time resolution weather generator for creating rainfall ensembles under different climatology scenarios. Those rainfall ensembles will be incorporated into hydrological models for simulating hydrological response under predicted climate changes.

  8. The evaluation of storm rainfall variability and its influence on runoff response at a catchment scale

    NASA Astrophysics Data System (ADS)

    David, Vaclav; Davidová, Tereza

    2015-04-01

    Storm rainfall events are usually very dynamic processes which are characterized by high spatial and temporal variability. It can influence the catchment response to the event a lot in terms of the shape and volume of response hydrographs. In this contribution, the variability of selected rainfall events is presented. It is assessed in terms of total volumes of precipitation which are an input to rainfall-runoff process. As a source of precipitation information, data from precipitation gauging stations were used which have one hour time step. Additionally, data originated from weather radar were used to describe spatial variability in more detail. Measured reflectivity data were transformed into the values of precipitation intensities which were compared to station data to make a check on the reliability of radar originated data. The assessment was carried out by the comparison of total precipitation to a catchment based on different extent of source data. Precipitation totals were calculated from station data using different methods including Thiessen polygons and different interpolation techniques. As a study area, the catchment of Blanice River was selected. This catchment is located in Central Bohemia Region and smaller part extends beyond it to South Bohemia Region. Its total area to the confluence to Sázava River is 543 km2. In this catchment, agricultural lands predominates but the percentage of forests is also not negligible. The area is in general hilly with important presence of steep slopes. The results of obtained by the analyses carried out show the high importance of the amount of available precipitation data and their quality. Despite the fact that the variability of precipitation can affect the distribution of runoff and consecutively the shape of response hydrograph, it can affect also the accuracy and representativeness of the information provided by point measurements of precipitation by gauges and by weather radars. Acknowledgement The research presented in this contribution has been carried out within the research projects NAZV KUS QJ1220233 'Assessment of former pond systems with aim to achieve sustainable management of water and soil resources in the Czech Republic' and SGS14/180/OHK1/3T/11 'Rainfall-runoff, erosion and transport processes - experimental research'. All the support is highly acknowledged.

  9. Analysis of TRMM Precipitation Radar Algorithms and Rain over the Tropics and Southeast Texas 

    E-print Network

    Funk, Aaron

    2013-12-10

    The Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) 2A23 algorithm classifies rain echo as stratiform or convective while the 2A25 algorithm corrects vertical profiles of radar reflectivity for attenuation and calculates rain...

  10. A status report on weather modification research in the Dakotas

    NASA Astrophysics Data System (ADS)

    Smith, Paul L.; Orville, Harold D.; Boe, Bruce A.; Stith, Jeffrey L.

    An overview of the status of weather modification research in North and South Dakota (USA) is presented. The operational North Dakota Cloud Modification Projects has, since 1976, been seeding summer convective clouds for the dual objectives of hail suppression and rainfall enhancement. Research being carried out as part of a Federal/State cooperative program, in coordination with the operational activities, has included physical and statistical evaluation studies as well as numerical cloud modeling investigations. The statistical analyses provide some indications that the intended seeding effects are being obtained. The physical studies involve aircraft and radar observations and emphasize tracer experiments to study the transport and dispersion of seeding agents and the activation of ice nuclei. The modeling studies simulate the experiments and aid in investigation of the process involved and the effects of seeding. The 1989 North Dakota Thunderstorm Project, a major field study emphasizing physical and numerical modeling studies, is described briefly.

  11. Dual-frequency precipitation radar (DPR) development on the global precipitation measurement (GPM) core observatory

    NASA Astrophysics Data System (ADS)

    Kojima, M.; Miura, T.; Furukawa, K.; Hyakusoku, Y.; Ishikiri, T.; Kai, H.; Iguchi, T.; Hanado, H.; Nakagawa, K.

    2012-11-01

    The Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core observatory is developed by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT). GPM objective is to observe global precipitation more frequently and accurately. GPM contributes to climate and water cycle change studies, flood prediction and numerical weather forecast. GPM consists of GPM core observatory and constellation satellites carrying microwave radiometers (MWRs) and/or sounders (MWSs). The frequent measurement will be achieved by constellation satellites, and the accurate measurement will be achieved by DPR with high sensitivity and dual frequency capability. GPM core observatory is jointly developed by National Aeronautics and Space Administration (NASA) and JAXA. NASA is developing the satellite bus and GPM microwave radiometer (GMI), and JAXA is developing DPR. GPM algorithms for data processing are developed jointly. The DPR consists of Ku-band (13.6 GHz) radar suitable for heavy rainfall in the tropical region, and Ka-band (35.55 GHz) radar suitable for light rainfall in higher latitude region. Drop size distribution information will be derived which contributes to the improvement of rainfall estimate accuracy. DPR will also play a key role to improve rainfall estimation accuracy of constellation satellites. DPR proto-flight test at JAXA Tsukuba space center is finished and it is delivered to NASA for integration to the GPM observatory. In this paper, DPR PFT test result at Tsukuba space center, DPR status in the GPM observatory environmental test, and DPR on-orbit calibration plan will be presented.

  12. Rainfall-Rate Estimation Using Gaussian Mixture Parameter Estimator: Training and Validation

    E-print Network

    -rate estimation, following a general framework based on the Gaussian mixtures model and Bayes least squaresRainfall-Rate Estimation Using Gaussian Mixture Parameter Estimator: Training and Validation develops a Gaussian mixture rainfall-rate estimator (GMRE) for polarimetric radar-based rainfall

  13. Rainfall-Rate Estimation Using Gaussian Mixture Parameter Estimator: Training and Validation

    E-print Network

    Homes, Christopher C.

    -rate estimation, following a general framework based on the Gaussian mixture model and Bayes least squaresRainfall-Rate Estimation Using Gaussian Mixture Parameter Estimator: Training and Validation develops a Gaussian mixture rainfall-rate estimator (GMRE) for polarimetric radar-based rainfall

  14. New weather forecasting aid

    NASA Astrophysics Data System (ADS)

    A new, computerized weather analysis and display system developed by the National Oceanic and Atmospheric Administration (NOAA) is being used to provide air traffic controllers in Colorado with up-to-date information on weather systems that could affect aircraft within their control areas. The system, called PROFS (Prototype Regional Observing and Forecasting Services), was under development for four years at NOAA's Environmental Research Laboratories in Boulder, and is undergoing operational evaluation at the Federal Aviation Administration's (FAA's) Denver Air Route Traffic Control Center in Longmont, Colo. FAA officials see the new system as a first step in upgrading the weather support services for the nation's air traffic control system. Originally created to help National Weather Service personnel with their forecasting duties (Eos, April 13, 1982, p. 233), the PROFS system was specially tailored for aviation use before being installed at the Longmont center. The system uses computers to process weather data from satellites, regional radar, wind profilers, a network of automated weather stations in eastern Colorado, and other sources, some of which are not normally available to forecasters. When this information is collected and formatted, weather personnel at the center can choose from several types of visual display on their terminals, depending on what information they require. The forecasters can then make printed copies of any display and distribute them within moments to controllers who use the information to alert air traffic to storms, wind shifts, and other weather disturbances.

  15. Geography & Weather. Weather Mapping.

    ERIC Educational Resources Information Center

    Mogil, H. Michael; Levine, Barbara G.

    1990-01-01

    Presented are 35 activities that center around television and newspaper weather reports. Geography, weather, and other disciplines are included as well as various grade levels. Available resource materials are listed and their uses explained. Parent, administrator, and other faculty member involvement is emphasized. (KR)

  16. Estimating Reservoir Inflow Using RADAR Forecasted Precipitation and Adaptive Neuro Fuzzy Inference System

    NASA Astrophysics Data System (ADS)

    Yi, J.; Choi, C.

    2014-12-01

    Rainfall observation and forecasting using remote sensing such as RADAR(Radio Detection and Ranging) and satellite images are widely used to delineate the increased damage by rapid weather changeslike regional storm and flash flood. The flood runoff was calculated by using adaptive neuro-fuzzy inference system, the data driven models and MAPLE(McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation) forecasted precipitation data as the input variables.The result of flood estimation method using neuro-fuzzy technique and RADAR forecasted precipitation data was evaluated by comparing it with the actual data.The Adaptive Neuro Fuzzy method was applied to the Chungju Reservoir basin in Korea. The six rainfall events during the flood seasons in 2010 and 2011 were used for the input data.The reservoir inflow estimation results were comparedaccording to the rainfall data used for training, checking and testing data in the model setup process. The results of the 15 models with the combination of the input variables were compared and analyzed. Using the relatively larger clustering radius and the biggest flood ever happened for training data showed the better flood estimation in this study.The model using the MAPLE forecasted precipitation data showed better result for inflow estimation in the Chungju Reservoir.

  17. Rainfall Research.

    ERIC Educational Resources Information Center

    Melber, Leah M.

    2003-01-01

    Presents procedures for weather studies as exciting and relatively simple research projects for students to perform. Expects that students gain an accurate view of the scientific process in addition to real-world experience as they face challenging setbacks and make unexpected discoveries along the way. Includes cross-curricular applications.…

  18. Indigenous Weather Knowledge

    NSDL National Science Digital Library

    Produced by the Commonwealth Bureau of Meteorology, this Web site exhibits seasonal weather calendars created by Indigenous people thousands of years ago. The site first discusses the Aboriginal people in Australia and their methods for dealing with past climate changes. Studying the calendars, users will notice that Indigenous people dealt with climate on a local scale and recognized a varying number of seasons. For comparison, the site presents the Bureau of Meteorology's Temperature and Rainfall Graphs and climate group classification maps. Because it is still in the early stages of development, users should revisit this site to learn more about Aboriginal knowledge of weather and climate.

  19. Evaluation of a Spectral-Based Nonlinear Stochastic Nowcasting Model (PhaSt) on Italian radar mosaic

    NASA Astrophysics Data System (ADS)

    Rhandhir Cummings, Garvin; Rebora, Nicola; Silvestro, Francesco

    2014-05-01

    Evaluation of a Spectral-Based Nonlinear Stochastic Nowcasting Model (PhaSt) on Italian radar mosaic G. Cummings1, N. Rebora2 and F. Silvestro2 1Hydrometeorological Service, Ministry of Agriculture, Georgetown, Guyana 2CIMA research foundation, Savona, Italy The forecasting of precipitation events and flash floods are critical for civil protection. The temporal and spatial resolution of weather radar data as the input for nowcasting models has shown significant promise in improving forecasts in recent years. This work aims to evaluate the performance of a Spectral-Based Nonlinear Stochastic Nowcasting Model (PhaSt) in the Italian radar domain with 76 rainfall events and to assess the hydrological applicability of the forecasts for small to medium size river basins. The results were validated by comparison of the forecasted precipitation fields with the radar observations and by computing simple forecast skill scores. In addition to model evaluation based on seasonal occurrence, the 76 weather events considered were also classified into 2 types: long-lived and spatially distributed (Type I) or brief and localized (Type II). The results showed that PhaSt produced good results for up to 60 minutes for all seasons and event types, and for all the selected model parameter values.

  20. Validation of Remotely-Sensed Rainfall Products and WRF-Model Outputs with Rain-Gauge Data in South-Central California

    NASA Astrophysics Data System (ADS)

    Ozcan, O.; Bookhagen, B.; Jones, C.; Musaoglu, N.

    2013-12-01

    Recent advantages in retrieving rainfall through remote-sensing data are important, although measurements are still associated with uncertainties. The increasing length of the satellite rainfall time series allow to create climatologies, but their statistics and characteristics has not been well validated across steep rainfall gradients. Correspondingly, accurate regional climate models are needed to assess the atmospheric mechanisms of extreme events. The Weather Research and Forecasting (WRF) model provides an ideal tool to analyze extreme events, but their validation is often hampered by lack of data. Here, we validate various remote sensing dataset and WRF model outputs with a unique rain-gauge dataset in Santa Barbara county, south-central California.This study evaluates the validation and intercomparison of remote sensing rainfall data from 15 years (1998-2012) of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar and passive microwave products (3B42, 2B31 and 2A25) and Doppler Next-Generation Radar (NEXRAD) products through comparison with 46 rainfall gauges in the vicinity of Santa Barbara. Additionally, we used WRF model outputs of selected strong rainfall storms during the same time period at 2x2 km grid spacing. Our primary goals are threefold: (1) assess the quality and the performance of TRMM and NEXRAD precipitation products, (2) perform an extensive validation focusing especially on hydrometeorological extreme events and (3) compare WRF model outputs for recent storms with gauge and remotely-sensed data. We rely on several statistics derived from 5-minute and hourly rainfall gauges that are accumulated to daily, monthly, and seasonal averages and then compared to remotely-sensed rainfall amounts. Statistical evaluations include the calculation of the 90th, 95th, 99th percentiles, their recurrence intervals, and analysing the three-parameter generalized extreme value (GEV) distribution. Spatial patterns and correlations of rainfall events across the study area are analysed. Preliminary results from the rain-gauge data indicate a steep rainfall gradient from Santa Barbara's coast to the Santa Ynez Range related to an orographic barrier. TRMM 3B42 data show a similar spatial pattern, but absolute rainfall amounts differ significantly from rain-gauge measurement. Recurrence intervals derived from rain-gauge measurements and TRMM 3B42 are similar when the rain-gauge stations are located at approximately the mean elevation of the related TRMM 3B42 grid cell. Hourly rainfall amounts extracted from two nearby radar stations (KVBX and KVTX, product N1P) have difficulties delineating absolute amounts, but show similar spatial patterns. Beam blockage through topography and maintenance issues prevents the construction of a continuous time series. WRF model outputs provide valuable information on rainfall at high spatial and temporal resolutions Our preliminary results indicate that TRMM 3B42 can be used to assess first-order rainfall statistics and recurrence intervals, but rainfall magnitudes vary significantly from ground measurements. Ultimately, the validated products can be used as a framework for predicting the impact of hydrologic events in this area.

  1. Radar volcano monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

    Arason, Þórður; Yeo, Richard F.; Sigurðsson, Geirfinnur S.; Pálmason, Bolli; von Löwis, Sibylle; Nína Petersen, Guðrún; Bjornsson, Halldór

    2013-04-01

    Weather radars are valuable instruments in monitoring explosive volcanic eruptions. Temporal variations in the eruption strength can be monitored as well as variations in plume and ash dispersal. Strength of the reflected radar signal of a volcanic plume is related to water content and droplet sizes as well as type, shape, amount and the grain size distribution of ash. The Icelandic Meteorological Office (IMO) owns and operates three radars and one more is planned for this radar volcano monitoring system. A fixed position 250 kW C-band weather radar was installed in 1991 in SW-Iceland close to Keflavík International Airport, and upgraded to a doppler radar in 2010. In cooperation with the International Civil Aviation Organization (ICAO), IMO has recently invested in two mobile X-band radars and one fixed position C-band radar. The fixed position 250 kW doppler C-band weather radar was installed in April 2012 at Fljótsdalsheiði, E-Iceland, and in June 2012 IMO received a mobile 65 kW dual-polarization doppler X-band radar. Early in 2013 IMO will acquire another mobile radar of the same type. Explosive volcanic eruptions in Iceland during the past 22 years were monitored by the Keflavík radar: Hekla 1991, Gjálp 1996, Grímsvötn 1998, Hekla 2000, Grímsvötn 2004, Eyjafjallajökull 2010 and Grímsvötn 2011. Additionally, the Grímsvötn 2011 eruption was mointored by a mobile X-band radar on loan from the Italian Civil Protection Authorities. Detailed technical information is presented on the four radars with examples of the information acquired during previous eruptions. This expanded network of radars is expected to give valuable information on future volcanic eruptions in Iceland.

  2. Radar-based Flood Warning Indicator for the Upper Oyster Creek Watershed in Sugar Land, Texas

    NASA Astrophysics Data System (ADS)

    Juan, A.; Fang, N.; Bedient, P.

    2012-12-01

    Over the last decade, there have been an increasing number of watersheds that relied on weather radars to provide accurate precipitation information for flood warning purposes. Radar-based flood warning systems as non-structural tools to provide accurate and timely warnings to the public and private entities are greatly needed for urban areas prone to flash floods. The major impetus of using a radar-based flood warning system is the increased flood warning lead-time, due to its wider spatial and temporal coverage when compared to rain and stream gages alone. Real-time NEXRAD rainfall estimation in conjunction with GIS enables flood alert systems to provide important advanced warning of impending flood conditions. 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 since 1997. This paper will discuss the development of a radar-based flood warning system for the City of Sugar Land, Texas, and also introduce the Flood Warning Indicator (FWI), which is a tool that utilizes real-time radar rainfall information to portray potential flooding problems in specific areas within a watershed through GIS mapping. The purpose of this tool is to serve as the first line of defense during storm events, especially for city officials to deploy personnel to the area of concern to verify and determine the extents of flooding. Having a significant role in the communication of flood information, FWI marks an important step towards the establishment of an operational and reliable flood warning system for the City of Sugar Land.

  3. Radar-based Flood Warning Indicator for the Upper Oyster Creek Watershed in Sugar Land, Texas

    NASA Astrophysics Data System (ADS)

    Fang, N.; Juan, A.; Bedient, P. B.

    2011-12-01

    Over the last decade, there have been an increasing number of watersheds that relied on weather radars to provide accurate precipitation information for flood warning purposes. Radar-based flood warning systems as non-structural tools to provide accurate and timely warnings to the public and private entities are greatly needed for urban areas prone to flash floods. The major impetus of using a radar-based flood warning system is the increased flood warning lead-time, due to its wider spatial and temporal coverage when compared to rain and stream gages alone. Real-time NEXRAD rainfall estimation in conjunction with GIS enables flood alert systems to provide important advanced warning of impending flood conditions. 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 since 1997. This paper will discuss the development of a radar-based flood warning system for the City of Sugar Land, Texas, and also introduce the Flood Warning Indicator (FWI), which is a tool that utilizes real-time radar rainfall information to portray potential flooding problems in specific areas within a watershed through GIS mapping. The purpose of this tool is to serve as the first line of defense during storm events, especially for city officials to deploy personnel to the area of concern to verify and determine the extents of flooding. Having a significant role in the communication of flood information, FWI marks an important step towards the establishment of an operational and reliable flood warning system for the City of Sugar Land.

  4. Atlanta Air Route Traffic Control Center's involvement in aviation weather

    NASA Technical Reports Server (NTRS)

    Wood, W. D.

    1979-01-01

    The distribution of weather information throughout the Air Traffic Control System is discussed along with the development of meteorological radar, and the modifications to the Air Route Traffic Control Center radars for locating and determining the severity of storms' cells. The planned improvements in the availability of weather data to the control centers are listed.

  5. Weather Forecasting

    NSDL National Science Digital Library

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

  6. ENVIRONMENTAL CHALLENGES TO OPERATIONALISATION OF SOUTH AFRICAN RAINFALL ENHANCEMENT

    Microsoft Academic Search

    Karen Shippey; André Görgens; Deon Terblanche; Mike Luger

    Most of the atmospheric moisture in systems moving across South Africa leaves the sub-continent as the weather systems move out over the ocean, only a tenth of it falls on the landmass as rain. An increase in the efficiency of the atmospheric moisture delivery system by means of rainfall enhancement is therefore an attractive concept. Rainfall enhancement functions by either

  7. Impact of Rainfall on the Productivity of Highway Construction

    Microsoft Academic Search

    Khaled El-Rayes; Osama Moselhi

    2001-01-01

    Heavy rainfall often leads to complete suspension of highway construction due to saturated and unworkable soil conditions. Therefore, quantifying the impact of rainfall on the productivity of highway con- struction is essential in preparing realistic schedules and cost estimates for the preconstruction stage and in analyzing weather-related claims for the postconstruction stage. This paper presents a decision support system for

  8. Predicting the Weather

    NSDL National Science Digital Library

    This Topic in Depth explores the science behind predicting the weather. First, the United States Search and Rescue Task Force describe the basic tools and knowledge used to create weather forecasts (1). Students can find concise, clear explanations of weather, fronts and air masses, high and low pressure, precipitation, and water vapor and humidity as well. By performing the activities presented in the second website, fourth grade students can learn about weather instruments and data collection (2). This website, produced by the Government of Saskatchewan, also explores how the weather can impact local communities. Third, Edheads offers a Macromedia Flash Player enhanced interactive module allowing students to predict the weather by examining weather maps (3 ). Through this website, users can become familiar with the concepts of warm and cold fronts, wind direction and speed, air pressure, and humidity. The fourth website, supplied by Annenberg / CPB, discusses weather satellites, Doppler radar, and additional tools forecasters use to predict the weather (4). Students can find a wind chill calculator along with a brief discussion of the history of forecasting and weather lore. Next, NOAA provides graphics for five forecast models: the ETA, the Global Forecast System (GFS), the Wave Watch III (WW3), the Nested Grid model (NGM), and the Rapid Update Cycle (RUC) (5). Outputs are available for North America, North Pacific, Western North Atlantic, and the Polar Ice Drift. Users can find links to detailed descriptions of the inputs and history of each model. Sixth, the British government's Met Office describes numerical modeling and its components (6). Students and educators can learn about the future in forecasting as well as educational opportunities with the Cooperative Program for Meteorology, Education, and Training (COMET).

  9. Nearshore Applications of Marine Radar 15 June 2006

    E-print Network

    Haller, Merrick

    wave and weather conditions 2.2 Marine radar wave imaging system 12 Radar properties and data collection parameters Nyquist wavenumber and frequency Data collection nomenclature Image stability of in situ wave and weather conditions 3.2 Data Collection Parameters 45 Digital collection parameters Data

  10. Conceptual Design of a Geostationary Radar for Monitoring Hurricanes

    Microsoft Academic Search

    Eastwood Im; Stephen L. Durden; Yahya Rahmat-Samii; Michael Lou; John Huang

    The current Geostationary Operational Environ- mental Satellites (GOES) are equipped to make cloud top measurements only. In contrast, a millimeter-wave radar allows 3-D measurements of precipitation associated with hurricanes and other convective systems. It also provides important inputs to numerical weather prediction models for improving the accuracy in weather nowcasting and forecasting. Recently, a novel 35-GHz Doppler radar instrument concept

  11. Relationship between intraseasonal oscillation and diurnal variation of summer rainfall over the South China Sea

    Microsoft Academic Search

    Chang-Hoi Ho; Myung-Sook Park; Yong-Sang Choi; Yukari N. Takayabu

    2008-01-01

    The diurnal variations in summer rainfall over the South China Sea (110°E-120°E, 10°N-20°N) are examined for active and inactive intraseasonal oscillation (ISO) periods that are characterized by strong and weak 850-hPa zonal winds, respectively. By analyzing the rainfall retrievals from the Tropical Rainfall Measuring Mission Precipitation Radar for the period 1999-2006, it is found that the peak rainfall during the

  12. A Simulation Study on the Torrential Rainfall over Plain Area of Southwestern Taiwan During the Invasion of Typhoon Fanapi (2010)

    NASA Astrophysics Data System (ADS)

    Yeh, T.-C.; Chen, D.-S.; Hsiao, L.-F.; Li, C.-H.; Cheng, M.-H.; Huang, K.-N.

    2012-04-01

    Tropical cyclone Fanapi was named on 15, September 2010. The storm then moved westward and then landed Taiwan on 19, September. During the invasion of Typhoon Fanapi, torrential rainfall occurred in Taiwan area. The maximum accumulated rainfall reaches 1,100 mm in mountainous area of southern Taiwan. The rainfall amount over mountainous area is not particular large comparing to those of other events such as the 2,800 mm of Typhoon Morakot (2009) and 1,500 mm of Typhoon Sinlaku (2008). However, the 6-hour accumulated rainfall amount 626 mm at Marjar township and the daily rainfall amount 872 mm at Kaohsiung city set the new record for Taiwan area and Kaohsiung city, respectively. Where Marjar township locates at the southern Central Mountain Range of Taiwan, and Kaohsiung city locates near the coast and is the major city in southern Taiwan. The intensive rainfall from Typhoon Fanapi, particularly heavy rains over plain area, is exceptional and is worth to do further investigation for improving forecast. In this study, detail observations from radars and local stations were collected and documented. Numerical simulations from a version of WRF model, called TWRF at the Central Weather Bureau, were conducted and analyzed. The TWRF was able to simulate the track of Typhoon Fanapi without large error when Typhoon Fanapi was near and moved over Taiwan. Large rainfall with intensive narrow band over southern Taiwan was simulated. From the simulations, we found that the topography and the structure of the storm caused such a record-breaking rainfall event. Stronger and boarder area of convergence were found on the southern portion of Typhoon Fanapi. The topography of Taiwan enhanced the rainfall over the upwind side of the flow approaches mountain. The slow down of the moving speed after the center moved over and reorganized on the western side of the mountain ridge prolonged the rainfall over Kaohsiung area. The speed, size and strength of the storm are crucial for Typhoon Fanapi to reorganize and maintain persisted heavy rains over the southwestern Taiwan.

  13. An Investigation of the Influence of Urban Areas on Rainfall Using the TRMM Satellite and a Cloud-Mesoscale Model

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall; OCStarr, David (Technical Monitor)

    2002-01-01

    A recent paper by Shepherd and Pierce (in press at Journal of Applied Meteorology) used rainfall data from the Precipitation Radar on NASA's Tropical Rainfall Measuring Mission's (TRMM) satellite to identify warm season rainfall anomalies downwind of major urban areas. Data (PR) were employed to identify warm season rainfall (1998-2000) patterns around Atlanta, Montgomery, Nashville, San Antonio, Waco, and Dallas. Results reveal an average increase of approx. 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 changes are relative to an upwind control area. It was also found that maximum rainfall rates in the downwind impact area exceeded 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. Results are consistent with METROMEX studies of St. Louis almost two decades ago and with more recent studies near Atlanta. A convective-mesoscale model with extensive land-surface processes is currently being employed to (a) determine if an urban heat island (UHI) thermal perturbation can induce a dynamic response to affect rainfall processes and (b) quantify the impact of the following three factors on the evolution of rainfall: (1) urban surface roughness, (2) magnitude of the UHI temperature anomaly, and (3) physical size of the UHI temperature anomaly. The sensitivity experiments are achieved by inserting a slab of land with urban properties (e.g. roughness length, albedo, thermal character) within a rural surface environment and varying the appropriate lower boundary condition parameters. The study will discuss the feasibility of utilizing satellite-based rainfall estimates for examining rainfall modification by urban areas on global scales and over longer time periods. The talk also introduces very preliminary results from the modeling component of the study. Such research has implications for weather forecasting, urban planning, water resource management, and understanding human impact on the environment and climate.

  14. WSR-88D doppler radar detection of corn earworm moth migration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flying insects, birds, and bats contribute to radar reflectivity and radial velocity measured by Doppler weather radars. A study was conducted in the Lower Rio Grande Valley of Texas to determine the capability of Weather Service Radar (version 88D) (WSR-88D) to monitor migratory flights of corn ea...

  15. The Use of Radar Imagery in Climatological Research. Resource Paper No. 21.

    ERIC Educational Resources Information Center

    Williams, Aaron, Jr.

    Intended to supplement undergraduate college geography courses, this resource paper investigates the need and use of radar in weather phenomena research. Radar can be used to study weather phenomena over a wide area, thus improving the results of statistical analyses previously limited by inadequate data. Radar techniques are also useful for…

  16. Radar echo signatures versus relative precipitation 

    E-print Network

    Huber, Terry Alvin

    1987-01-01

    the evolutionary processes of and within the cell. Radar is well suited for this purpose. Once hydrometeors within the cloud attain minimum detectable size, the cloud's evolution may be tracked using radar. The lifecycle of cell echoes, from initial detection... of the detected signal by the earth's surface). A radar which has been correctly calibrated can produce rainfa'll estimates that are very reasonable. But, depending on the specific application and location of the radar, an elevation-scan angle between 28 0...

  17. Rainfall Variability of South East Queensland

    NASA Astrophysics Data System (ADS)

    Wilson, Louise; Manton, Michael; Siems, Steven

    2010-05-01

    The seasonal weather of southeastern Queensland (SEQ) is commonly described by a wet and a dry season. Rainfall in this area has been declining for the past fifty years and climate projections indicate decreasing trends in annual rainfall and increases in temperature. These factors combined with population growth suggest a need for Queensland to re-evaluate its water management. In order to understand the rainfall variability of SEQ, it is useful to consider the impact of the different weather patterns or synoptic regimes on the regional rainfall. Previous studies have examined the synoptic patterns associated with extreme wind and rainfall events in SEQ and the correlation between rainfall in northern Queensland and atmospheric variables, but a comprehensive climatology for the SEQ region is missing. Analysis of routine soundings is found to reveal relationships between surface precipitation and atmospheric structure. Cluster analysis was performed on daily radiosonde data for Brisbane Airport spanning the period 01/01/1990-11/11/2009. The clustering was initially performed on seven atmospheric variables: total-totals, 850mb winds, wind shear between 850mb and 500mb, moisture flux and total water calculated from the sounding data. A sensitivity study reveals that the moisture flux parameters followed by total water and total-totals are the key variables in determining the regimes. The clusters were combined with daily rainfall records spanning the period 01/01/1995 - 01/06/2008 to determine the contribution of each regime to monthly rainfall. The seven-cluster case describes three separate southeasterly regimes, three westerly regimes and an easterly regime. The contribution of each regime to annual rainfall was also determined. The regimes for SEQ can be divided into ‘wet' and ‘dry' cases. It is apparent that the rainfall is largely limited to the coastal strip, with maxima near regions with steep terrain. The main rainfall period is from November through to February, with peak falls tending to be in February. The ‘wet' regimes are responsible for the majority of the region's rainfall. Southeasterly wind regimes are commonly associated with trade wind or ‘stream' showers and coastal trade wind cumulus. When there is significant moisture such as for the ‘moist' southeasterly regime these systems can bring significant rainfall to the region. The northwesterly regime can produce deep convection and contributes greatly to the total annual rainfall (21.7%) despite occurring less than 7% of the time. The easterly and westerly regimes also are major contributors to annual rainfall. There are also significant rainfall events during the dry season such as intense sub-tropical cyclones (east-coast lows) that bring sustained strong winds and intense rainfall to the region. In general, however, the winter season is dry and is well described by a southwesterly regime and a ‘dry' southeasterly regime. The dominant synoptic regime, the southeasterly regime, does not contribute significantly to the total rainfall in any month. The relationship between the Southern Oscillation Index (SOI) and rainfall over most of Queensland is strong. The correlation between SEQ monthly rainfall anomalies and the Southern Oscillation Index (SOI) was calculated over the period 1858-2008. A small but significant correlation is found between the SOI and rainfall in southeastern Queensland. The low correlation indicates that the rainfall is controlled by other factors in addition to the El Nino - Southern Oscillation.

  18. Weather Watch

    ERIC Educational Resources Information Center

    Bratt, Herschell Marvin

    1973-01-01

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

  19. Weather Vane

    NSDL National Science Digital Library

    Fresno Community Science Workshop

    2011-01-01

    In this meteorology activity, learners build weather vanes using straws, paperclips, and cardstock. Learners will explore wind and air resistance as well as how weather vanes are used to understand and predict weather.

  20. Nearshore Processes, Currents and Directional Wave Spectra Monitoring Using Coherent and Non-coherent Imaging Radars

    NASA Astrophysics Data System (ADS)

    Trizna, D.; Hathaway, K.

    2007-05-01

    Two new radar systems have been developed for real-time measurement of near-shore processes, and results are presented for measurements of ocean wave spectra, near-shore sand bar structure, and ocean currents. The first is a non-coherent radar based on a modified version of the Sitex radar family, with a data acquisition system designed around an ISR digital receiver card. The card operates in a PC computer with inputs from a Sitex radar modified for extraction of analogue signals for digitization. Using a 9' antenna and 25 kW transmit power system, data were collected during 2007 at the U.S. Army Corps of Engineers Field Research Facility (FRF), Duck, NC during winter and spring of 2007. The directional wave spectrum measurements made are based on using a sequence of 64 to 640 antenna rotations to form a snapshot series of radar images of propagating waves. A square window is extracted from each image, typically 64 x 64 pixels at 3-m resolution. Then ten sets of 64 windows are submitted to a three-dimensional Fast Fourier Transform process to generate radar image spectra in the frequency-wavenumber space. The relation between the radar image spectral intensity and wave spectral intensity derived from the FRF pressure gauge array was used for a test set of data, in order to establish a modulation transfer function (MTF) for each frequency component. For 640 rotations, 10 of such spectra are averaged for improved statistics. The wave spectrum so generated was compared for extended data sets beyond those used to establish the MTF, and those results are presented here. Some differences between the radar and pressure sensor data that are observed are found to be due to the influence of the wind field, as the radar echo image weakens for light winds. A model is developed to account for such an effect to improve the radar estimate of the directional wave spectrum. The radar ocean wave imagery is severely influenced only by extremely heavy rain-fall rates, so that acceptable quality were assured for most weather conditions on a diurnal basis using a modest tower height. A new coherent microwave radar has recently been developed by ISR and preliminary testing was conducted in the spring of 2007. The radar is based on the Quadrapus four-channel transceiver card, mixed up to microwave frequencies for pulse transmission and back down to base-band for reception. We use frequency-modulated pulse compression methods to obtain 3-m spatial resolution. A standard marine radar pedestal is used to house the microwave components, and rotating radar PPI images similar to marine radar images are obtained. Many of the methods used for the marine radar system have been transferred to the coherent imaging radar. New processing methods applied to the coherent data allow summing of radial velocity images to map mean currents in the near shore zone, such as rip currents. A pair of such radars operating with a few hundred meter separation can be used to map vector currents continuously in the near shore zone and in harbors on a timely basis. Results of preliminary testing of the system will be presented.

  1. Critical Rainfall Conditions Triggering Shallow Landslides or Debris Flows in Torrents - Analysis of Debris Flow events 2012, 2013 and 2014 in Austria

    NASA Astrophysics Data System (ADS)

    Moser, Markus; Mehlhorn, Susanne; Janu, Stefan

    2015-04-01

    Generally, debris flows are caused by both small-scale intensive precipitation and long lasting rainfalls with lower intensity but high pre-wetting or both combined. The triggering mechanism of the debris flow events in Austria 2012, 2013 and 2014 were mass movements (rapid shallow landslides) on steep slopes in the upper catchments. Those masses slide with very high velocity into the torrent beds provoking hyperconcentrated flows or debris flows. In areas of the geologically unstable Greywacke zone, the torrents were cleared up onto the bedrock and the debris was deposited in the storage areas of existing debris flow breakers or in torrents without technical protection measures the debris caused catastrophic damage to residential buildings and other infrastructural facilities on the alluvial fan. Following the events, comprehensive documentation work was undertaken comprising precipitation analysis (rainfall data, weather radar data), identification and quantification of the landslide masses, cross profiles along the channel and of deposition in the storage areas or on the fan. The documentation and analysis of torrential events is an essential part of an integrated risk management. It supports the understanding of the occurred processes to mitigate future hazards. Unfortunately, the small-scale heavy rain events are not detected by the precipitation stations. Therefore, weather radar data (INCA-Data) analysis was used to determine the - usually very local - intensities which caused those catastrophic landslides and debris flows. Analysis results showed an agreement with the range of the previously known precipitation thresholds for debris flow triggering in the Alps.

  2. ENSO modulates rainfall in the Mediterranean Californias

    Microsoft Academic Search

    Edgar G. Pavía; Antoine Badan

    1998-01-01

    A remarkable correlation is found between the total annual rainfall at Ensenada and the annual signal of the Southern Oscillation Index by suitably averaging their corresponding monthly series and dephasing the indices by four months. The result confirms the suspected dominant influence of El Niño-Southern Oscillation (ENSO) in the interannual weather fluctuations of mid-latitude mediterranean climates and shows that their

  3. A Bistatic Multiple-Doppler Radar Network

    Microsoft Academic Search

    Joshua Wurman; Stanley Heckman; Dennis Boccippio

    1993-01-01

    A multiple-Doppler radar network can be constructed using only one, traditional, transmitting pencil-beam radar and one or more passive, low-gain, nontransmitting receivers at remote sites. Radiation scattered from the pencil beam of the transmitting radar as it penetrates weather targets can be detected at the receive-only sites as well as at the active transmitter. The Doppler shifts of the radiation

  4. 32nd Conf. Radar Meteorology Albuquerque, NM, 2005

    E-print Network

    Xue, Ming

    32nd Conf. Radar Meteorology Albuquerque, NM, 2005 J1J.4 MULTIPLE DOPPLER WIND ANALYSIS AND ASSIMILATION VIA 3DVAR USING SIMULATED OBSERVATIONS OF THE PLANNED CASA NETWORK AND WSR-88D RADARS Jidong Gao, Norman 1. Introduction The advantages of using Doppler weather radar to track and forecast mesoscale

  5. Microwave Power Modules (MPMs) Miniature Microwave Amplifiers for Radars

    Microsoft Academic Search

    Tom Ninnis

    A recent and dramatic shift with military aircraft has been the widespread use of UAVs (unmanned aerial vehicles). Most previous-generation UAVs do not carry radar and, therefore, do not have all-weather visibility. But now, nearly all large UAVs have radars as standard equipment. UAVs require miniature and lightweight radars with low power consumption. Previously, there was little demand for such

  6. Classification of radar clutter in an air traffic control environment

    Microsoft Academic Search

    SIMON HAYKIN; WOLFGANG STEHWIEN; CONG DENG; PETER WEBER; RICHARD MANN

    1991-01-01

    The results of an experimental study aimed at the classification of radar clutter encountered on ground-based coherent scanning radar systems used for air traffic control are presented. The clutter signals of interest are primarily those due to birds and to clouds and weather systems. A historical perspective on the radar clutter classification problem is given, and related issues are discussed.

  7. A total electron content space weather study of the nighttime Weddell Sea Anomaly of 1996/1997 southern summer with TOPEX/Poseidon radar altimetry

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko

    2006-12-01

    This paper reports on a total electron content space weather study of the nighttime Weddell Sea Anomaly, overlooked by previously published TOPEX/Poseidon climate studies, and of the nighttime ionosphere during the 1996/1997 southern summer. To ascertain the morphology of spatial TEC distribution over the oceans in terms of hourly, geomagnetic, longitudinal and summer-winter variations, the TOPEX TEC, magnetic, and published neutral wind velocity data are utilized. To understand the underlying physical processes, the TEC results are combined with inclination and declination data plus global magnetic field-line maps. To investigate spatial and temporal TEC variations, geographic/magnetic latitudes and local times are computed. As results show, the nighttime Weddell Sea Anomaly is a large (˜1,600(°)2; ˜22 million km2 estimated for a steady ionosphere) space weather feature. Extending between 200°E and 300°E (geographic), it is an ionization enhancement peaking at 50°S-60°S/250°E-270°E and continuing beyond 66°S. It develops where the spacing between the magnetic field lines is wide/medium, easterly declination is large-medium (20°-50°), and inclination is optimum (˜55°S). Its development and hourly variations are closely correlated with wind speed variations. There is a noticeable (˜43%) reduction in its average area during the high magnetic activity period investigated. Southern summer nighttime TECs follow closely the variations of declination and field-line configuration and therefore introduce a longitudinal division of four (Indian, western/eastern Pacific, Atlantic). Northern winter nighttime TECs measured over a limited area are rather uniform longitudinally because of the small declination variation. TOPEX maps depict the expected strong asymmetry in TEC distribution about the magnetic dip equator.

  8. Comparison of simulated and actual wind shear radar data products

    NASA Technical Reports Server (NTRS)

    Britt, Charles L.; Crittenden, Lucille H.

    1992-01-01

    Prior to the development of the NASA experimental wind shear radar system, extensive computer simulations were conducted to determine the performance of the radar in combined weather and ground clutter environments. The simulation of the radar used analytical microburst models to determine weather returns and synthetic aperture radar (SAR) maps to determine ground clutter returns. These simulations were used to guide the development of hazard detection algorithms and to predict their performance. The structure of the radar simulation is reviewed. Actual flight data results from the Orlando and Denver tests are compared with simulated results. Areas of agreement and disagreement of actual and simulated results are shown.

  9. Dual Ka-band radar field campaign for GPM/DPR algorithm development

    NASA Astrophysics Data System (ADS)

    Nakagawa, K.; Nishikawa, M.; Nakamura, K.; Komachi, K.; Hanado, H.; Kawamura, S.; Sugitani, S.; Minda, H.; Shimizu, S.; Oki, R.

    2012-04-01

    The Global Precipitation Measurement (GPM) mission is an expanded follow-on mission to TRMM (Tropical Rainfall Measuring Mission) and a GPM core satellite will carry dual frequency precipitation radar (DPR) and a GPM Microwave Imager on board. The DPR, which is being developed by National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA), consists of two radars; Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The DPR is expected to advance precipitation science by expanding the coverage of observations to higher latitudes than those of the TRMM/PR, measuring snow and light rain by the KaPR, and providing drop size distribution information based on the differential attenuation of echoes at two frequencies. In order to secure the quality of precipitation estimates, ground validation (GV) of satellite data and retrieval algorithms is essential. Since end-to-end comparisons between instantaneous precipitation data observed by satellite and ground-based instruments is not enough to improve the algorithms. The error of various physical parameters in the precipitation retrieval algorithms (e.g. attenuation factor, drop size distribution, terminal velocity, density of the snow particles, etc.) will be estimated by the comparison with the ground-based observation data. A dual Ka-band radar system is developed by the JAXA for the GPM/DPR algorithm development. The dual Ka-radar system which consists of two identical Ka-band radars can measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those parameters are important particularly for snow measurement. Using the dual Ka-radar system along with other instruments, such as a polarimetric precipitation radar, a wind-profiler radar, ground-based precipitation measurement systems, the uncertainties of the parameters in the DPR algorithm can be reduced. The verification of improvement of rain retrieval with the DPR algorithm is also included as an objective. Observations using the dual Ka-radar system were performed in Okinawa Island, in Tsukuba, over the slope of Mt. Fuji, and in Nagaoka, Japan. In Okinawa Island, the performance of the measurement has been confirmed by rain observation. In Tsukuba, one radar was directed in vertical and the other was in slant direction. By this configuration, total attenuation in the melting layer was estimated. The objective of the Mt. Fuji experiment was to observe the melting layer. The X-band polarimetric radar was simultaneously operated. Unfortunately, the melting layer did not come in between the two radars due to warm weather. In Nagaoka, a lot of wet snow fell, and much data on the snow have been obtained. The main results are the k-Ze relationships. For the rain, reasonable k-Ze relationship has been obtained. The feasibility of total attenuation in melting layer has been studied. Different k-Ze relationships have been obtained in snow observations. The vertical variations of rainfall are also analyzed for the DPR algorithm development.

  10. Impacts of Polarimetric CASA Radar Observations on a Distributed Hydrologic Model

    NASA Astrophysics Data System (ADS)

    Chandrasekar, Venkatachalam; Chen, Haonan; Seo, Dong-Jun

    2013-04-01

    Radar can monitor the atmospheric conditions of a wide area very quickly and provide advanced observations and warnings for the precipitation systems at high spatial resolution. Over the past two decades, significant progress has been made in dual-polarization radar quantitative precipitation estimations (QPE). The polarimetric radar observations can provide more information on the drop size distribution and hydrometeor classifications over traditional Z-R methods. Among different rainfall algorithms, the Kdp-based QPE was proved to be immune to the partial beam blockage and hail contamination, and it is also less prone to the calibration errors. The networked Kdp-based QPE system developed by the U.S. National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has shown a great improvement compared with state-of-the-art. The high spatial and temporal resolution rainfall products from CASA QPE system can serve as a reliable data input for distributed hydrological models. The Research Distributed Hydrologic Model (RDHM) developed by the U.S. National Weather Service (NWS) Office of Hydrologic Development (OHD) is a promising tool for generating streamflow and other hydrological information such as soil moisture, etc. It can incorporate the heat transfer (HT) dynamics with the Sacramento soil moisture accounting model (SAC) to simulate rainfall-runoff and channel routing models for routing streamflow. In this research, the SAC-HT model was forced using hourly rainfall estimates produced by the CASA X-band dual-polarization radar network, for the purpose of predicting hydrological response and dealing with the flash flood issues. This paper will present a brief overview of the CASA QPE system and its various products. Then, the impacts of CASA QPE on SAC-HT model are mainly focused on, by using the networked polarimetric radar observations collected in IP-1 test bed in Southwestern Oklahoma. The "first" observation in CASA's urban demonstration network being deployed in the populous Dallas-Fort Worth (DFW) metroplex is also expected for the hydrological analysis.

  11. The Orbital Checkout Status of the Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core observatory

    NASA Astrophysics Data System (ADS)

    Miura, Takeshi; Kojima, Masahiro; Furukawa, Kinji; Hyakusoku, Yasutoshi; Ishikiri, Takayuki; Kai, Hiroki; Iguchi, Toshio; Hanado, Hiroshi; Nakagawa, Katsuhiro

    2014-05-01

    The Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core observatory is developed by Japan Aerospace Exploration Agency (JAXA) with National Institute of Information and Communications Technology (NICT). GPM objective is to observe global precipitation more frequently and accurately. GPM contributes to climate and water cycle change studies, flood prediction and numerical weather forecast. GPM consists of the GPM core observatory and constellation satellites carrying microwave radiometers (MWRs) and/or sounders (MWSs). The frequent measurement will be achieved by constellation satellites, and the accurate measurement will be achieved by the DPR with high sensitivity and dual frequency capability. The GPM core observatory is jointly developed by National Aeronautics and Space Administration (NASA) and JAXA. NASA is developing the satellite bus and GPM microwave radiometer (GMI), and JAXA is developing the DPR. The DPR consists of Ku-band (13.6 GHz) radar suitable for heavy rainfall in the tropical region, and Ka-band (35.55 GHz) radar suitable for light rainfall in higher latitude region. Drop size distribution information will be derived which contributes to the improvement of rainfall estimate accuracy. DPR will also play a key role to improve rainfall estimation accuracy of constellation satellites. DPR proto-flight test at JAXA Tsukuba space center has been completed in February 2012. The DPR has handed over to NASA and integrated to the core observatory in May 2012. The system test of the core observatory has completed in November 2013 and DPR test results satisfied its system requirements. The core observatory was shipped to launch site of JAXA Tanegashima space center in Japan. Launch site activities have started on November 2013 and GPM core observatory will be launched in early 2014. DPR orbital check out will be started in March 2014 and it will be completed in April 2014. In this presentation, the orbital check out status of DPR will be reported.

  12. Integration of Weather Avoidance and Traffic Separation

    NASA Technical Reports Server (NTRS)

    Consiglio, Maria C.; Chamberlain, James P.; Wilson, Sara R.

    2011-01-01

    This paper describes a dynamic convective weather avoidance concept that compensates for weather motion uncertainties; the integration of this weather avoidance concept into a prototype 4-D trajectory-based Airborne Separation Assurance System (ASAS) application; and test results from a batch (non-piloted) simulation of the integrated application with high traffic densities and a dynamic convective weather model. The weather model can simulate a number of pseudo-random hazardous weather patterns, such as slow- or fast-moving cells and opening or closing weather gaps, and also allows for modeling of onboard weather radar limitations in range and azimuth. The weather avoidance concept employs nested "core" and "avoid" polygons around convective weather cells, and the simulations assess the effectiveness of various avoid polygon sizes in the presence of different weather patterns, using traffic scenarios representing approximately two times the current traffic density in en-route airspace. Results from the simulation experiment show that the weather avoidance concept is effective over a wide range of weather patterns and cell speeds. Avoid polygons that are only 2-3 miles larger than their core polygons are sufficient to account for weather uncertainties in almost all cases, and traffic separation performance does not appear to degrade with the addition of weather polygon avoidance. Additional "lessons learned" from the batch simulation study are discussed in the paper, along with insights for improving the weather avoidance concept. Introduction

  13. Does cloud type affect rainfall?

    NSDL National Science Digital Library

    2006-10-31

    Scientists have studied the physical properties of clouds and have developed instruments onboard satellites to characterize the types of clouds they see below. Some satellites have instruments that allow them to measure rainfall as well. For this lesson, students will hypothesize what types of clouds they believe will create the most precipitation (rainfall) over Nashville, TN. Students use the Live Access Server (LAS) to obtain Cloud Coverage data that represents what percentage of the sky is covered by a certain type of cloud. They then compare the cloud coverage data to precipitation data provided by the National Weather Service's Climate Prediction Center. The lesson provides detailed procedure, related links, sample graphs, follow-up questions, extensions, and teacher notes.

  14. Wageningen Urban Rainfall Experiment 2014 (WURex14): Experimental Setup and First Results

    NASA Astrophysics Data System (ADS)

    van Leth, Thomas; Uijlenhoet, Remko; Overeem, Aart; Leijnse, Hidde; Hazenberg, Pieter

    2015-04-01

    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, e.g. Africa, Latin America, and large parts of Asia. 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 recently launched core satellite of 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 two co-located microwave links installed between two major buildings on the Wageningen University campus, approximately 2 km apart: a 38 GHz commercial microwave link, kindly provided to us by T-Mobile NL, and a 38 GHz dual-polarization research microwave link 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 a Parsivel optical disdrometer, located close to the mast on the receiving end of the links. During the course of the experiment, a 26 GHz RAL research microwave link was added to the experimental setup. Temporal sampling of the received signals was performed at a rate of 20 Hz. In addition, two time-lapse cameras have been installed on either side of the path to monitor the wetness of the antennas as well as the state of the atmosphere. Approximately halfway along the link path a rain gauge from the KNMI operational network is located. Finally, data is available from several commercial microwave links in the vicinity of the experimental setup, as well as from the KNMI weather radars. We report on the first results from this experiment, collected during the Summer and Fall of 2014.

  15. Wageningen Urban Rainfall Experiment 2014 (WURex14): Experimental Setup and First Results

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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, e.g. Africa, Latin America, and large parts of Asia. 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 recently launched core satellite of 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 two co-located microwave links installed between two major buildings on the Wageningen University campus, approximately 2 km apart: a 38 GHz commercial microwave link, kindly provided to us by T-Mobile NL, and a 38 GHz dual-polarization research microwave link 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 a Parsivel optical disdrometer, located close to the mast on the receiving end of the links. During the course of the experiment, a 26 GHz RAL research microwave link was added to the experimental setup. Temporal sampling of the received signals was performed at a rate of 20 Hz. In addition, two time-lapse cameras have been installed on either side of the path to monitor the wetness of the antennas as well as the state of the atmosphere. Approximately halfway along the link path a rain gauge from the KNMI operational network is located. Finally, data is available from several commercial microwave links in the vicinity of the experimental setup, as well as from the KNMI weather radars. We report on the first results from this experiment, collected during the Summer and Fall of 2014.

  16. National Severe Weather Workshop 2005

    NSDL National Science Digital Library

    The National Severe Weather Workshop 2005 is "a national forum for emergency management and media to exchange information and techniques for public safety during severe weather." The website supplies the tentative agenda for the three-day conference March 3-5, which includes many speeches from NOAA's weather partners in Norman. Interested visitors can find information on registration materials, opportunities to exhibit, and lodging. While information is not yet available on the planning members, users can find links to the sponsors and a notice about free radar and spotter training.

  17. From Rainfall Downscaling to Rainfall Retrieval: Inverse Problems of Similar Nature

    NASA Astrophysics Data System (ADS)

    Foufoula, Efi; Ebtehaj, Mohammad

    2014-05-01

    Satellite-based rainfall estimation offers the possibility of tracking global patterns of rainfall over ocean and land for large-scale hydrologic modeling, and for improved analysis of local and regional rainfall where ground observations are not available. In the past decade, high-resolution retrieval of rainfall from their spaceborne microwave spectral radiative fluxes has been an active area of research in the hydro-meteorological community. However, most current retrieval algorithms cannot properly reproduce low and extreme rainfall intensities and the small-scale precipitation variability, especially over land and coastal areas - important for hydrologic predictions and hazard mitigation. In this research, we introduce a new approach to the spaceborne passive microwave rainfall retrieval problem. The proposed methodology is inspired by the state-of-the-art supervised manifold learning and Bayesian shrinkage estimation paradigms and takes advantage of precipitation sparsity, recently documented and explored by the authors in precipitation downscaling, estimation, and data assimilation. The retrieval methodology relies on a sparsity-promoting search between two dictionaries that encode rainfall intensities and their spectral signatures. The proposed framework is examined using observations of the active precipitation radar (PR) and the passive microwave imager (TMI) on board of the Tropical Rainfall Measuring Mission (TRMM) satellite. The essence of the algorithm is explained and its advantages are highlighted in comparison with the outputs of the currently operational algorithms.

  18. Performance evaluation of the retrieval of a two hours rainfall event through microwave tomography applied to a network of radio-base stations

    NASA Astrophysics Data System (ADS)

    Facheris, L.; Cuccoli, F.; Baldini, L.

    2012-04-01

    Critical precipitation events occurred over the Italian territory have been often characterized by high intensity and very fast development, frequently over small catchment areas. The detection of this kind of phenomena is a major issue that poses remarkable problems that cannot be tackled completely only with 'standard' instrumentation (even when available), such as a weather radars or raingauges. Indeed, the rainfall sampling modalities of these instruments may jeopardize the attempts to provide a sufficiently fast risk alert: - the point-like, time-integrated way of sampling of raingauges can completely/partially miss local rainfall cores of high intensity developing in the neighborhoods. Moreover, raingauges provide cumulated rainfall measurements intrinsically affected by a time delay. - In the case of weather radars, several factors may limit the advantages brought by range resolution and instantaneous sampling: precipitation might be sampled at an excessive height due to the distance of the radar site and/or the orography surrounding the valleys/catchments where the aforementioned kind of events is more likely to form up; distance may limit the resolution in the cross-range direction; beam screening due to orography causes a loss of power that is interpreted in the farther range bins as a reduced precipitation intensity. In this context, a positive role for flagging the criticality of a precipitation event can be played by signal attenuation measurements made along microwave links, as available through the infrastructure of a mobile communications network. Three are the interesting features of such networks: 1) the communications among radio-base stations occur where point-to-point electromagnetic visibility is guaranteed, namely along valleys or between tops/flanks of hills or mountains; 2) the extension of these links (few kilometres) is perfectly compatible with the detection of severe but localized precipitation events; 3) measurements can be made on a practically continuous-time basis. In the past years, we showed that new scenarios for tomographic rainfall monitoring have been disclosed by the availability of widespread networks of radio-base stations for mobile communications (i.e., GSM, GPRS, UMTS). Such networks could be employed as the backbone of a low cost system able to provide 2D estimates of rainfall in real time. Monitoring capabilities increase in more populated sites, as urban areas, where such radio links form up a dense network that can be exploited to get detailed information also about structure and evolution of rainfall phenomena. In 2010, we presented a novel tomographic processing method for rainfall rate estimation, specifically adaptable to the dense and asymmetric topologies of urban networks of radio-base stations. In this paper, we show its application to a simulated time sequence of specific attenuation (K) maps, derived from true weather radar data gathered during a rainfall event specifically selected to evaluate the performance of the tomographic retrieval in critical conditions. The event was in fact very localized and intense and lasted two hours. 12 GHz is assumed for the carrier frequency of the radio-base network. We show the reconstruction performance of the 2D K fields achieved resorting first to a symmetric, regular network and then to a couple of totally asymmetric ones.

  19. Radar Entomology

    NSDL National Science Digital Library

    0000-00-00

    Radar tracking used to profile insect migration, mating and flight patterns. Many links to various pages include current workers in radar entomology, historical uses of the technology, and many images.

  20. UM Weather

    NSDL National Science Digital Library

    Sponsored by The Weather Underground at the University of Michigan at Ann Arbor, UM Weather bills itself as the "Internet's premier source of weather information." The site offers several general audience tools such as the Fast Forecast for any city in the US, ski weather, and weather cams. But, it also provides access to over two dozen weather software packages, a new computer model forecasts page, and most impressively a list of close to 400 other weather related Web sites. Professionals and researchers will appreciate the non-technical feel of the site and the valuable information they can procure from it.

  1. Severe Weather

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2005-04-01

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

  2. System concept for the next-generation spaceborne precipitation radars

    Microsoft Academic Search

    E. Im; S. L. Durden; G. Sadowy; A. Berkun; J. Huang; M. Lou; B. C. Lopez; Y. Rahmat-Samii; S. Rengarajan

    2000-01-01

    The 13.8-GHz Precipitation Radar (PR) aboard the US\\/Japan Tropical Rainfall Measuring Mission (TRMM) satellite is the first rain profiling radar ever launched into space. A TRMM follow-on mission, called the Global Precipitation Mission (GPM), is currently planned to extend and to improve the TRMM acquired rainfall data set. One of the key components of the GPM science instrumentation is an

  3. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

  4. A multiplier-based method of generating stochastic areal rainfall from point rainfalls

    NASA Astrophysics Data System (ADS)

    Ndiritu, J. G.

    Catchment modelling for water resources assessment is still mainly based on rain gauge measurements as these are more easily available and cover longer periods than radar and satellite-based measurements. Rain gauges however measure the rain falling on an extremely small proportion of the catchment and the areal rainfall obtained from these point measurements are consequently substantially uncertain. These uncertainties in areal rainfall estimation are generally ignored and the need to assess their impact on catchment modelling and water resources assessment is therefore imperative. A method that stochastically generates daily areal rainfall from point rainfall using multiplicative perturbations as a means of dealing with these uncertainties is developed and tested on the Berg catchment in the Western Cape of South Africa. The differences in areal rainfall obtained by alternately omitting some of the rain gauges are used to obtain a population of plausible multiplicative perturbations. Upper bounds on the applicable perturbations are set to prevent the generation of unrealistically large rainfall and to obtain unbiased stochastic rainfall. The perturbations within the set bounds are then fitted into probability density functions to stochastically generate the perturbations to impose on areal rainfall. By using 100 randomly-initialized calibrations of the AWBM catchment model and Sequent Peak Analysis, the effects of incorporating areal rainfall uncertainties on storage-yield-reliability analysis are assessed. Incorporating rainfall uncertainty is found to reduce the required storage by up to 20%. Rainfall uncertainty also increases flow-duration variability considerably and reduces the median flow-duration values by an average of about 20%.

  5. BBC Weather

    NSDL National Science Digital Library

    At this website, the BBC offers an array of materials dealing with weather. Meteorologists can discover employment opportunities. Individuals with spectacular photographs of weather phenomenon can submit their images to the photo gallery. Students and educators can find introductory materials on basic weather concepts, forecasting, extreme events, and broadcasting the weather. The website offers fun weather-related games and projects, a meteorology glossary, and links to other educational websites.

  6. The Effects of Rainfall Inhomogeneity on Climate Variability of Rainfall Estimated from Passive Microwave Sensors

    NASA Technical Reports Server (NTRS)

    Kummerow, Christian; Poyner, Philip; Berg, Wesley; Thomas-Stahle, Jody

    2007-01-01

    Passive microwave rainfall estimates that exploit the emission signal of raindrops in the atmosphere are sensitive to the inhomogeneity of rainfall within the satellite field of view (FOV). In particular, the concave nature of the brightness temperature (T(sub b)) versus rainfall relations at frequencies capable of detecting the blackbody emission of raindrops cause retrieval algorithms to systematically underestimate precipitation unless the rainfall is homogeneous within a radiometer FOV, or the inhomogeneity is accounted for explicitly. This problem has a long history in the passive microwave community and has been termed the beam-filling error. While not a true error, correcting for it requires a priori knowledge about the actual distribution of the rainfall within the satellite FOV, or at least a statistical representation of this inhomogeneity. This study first examines the magnitude of this beam-filling correction when slant-path radiative transfer calculations are used to account for the oblique incidence of current radiometers. Because of the horizontal averaging that occurs away from the nadir direction, the beam-filling error is found to be only a fraction of what has been reported previously in the literature based upon plane-parallel calculations. For a FOV representative of the 19-GHz radiometer channel (18 km X 28 km) aboard the Tropical Rainfall Measuring Mission (TRMM), the mean beam-filling correction computed in this study for tropical atmospheres is 1.26 instead of 1.52 computed from plane-parallel techniques. The slant-path solution is also less sensitive to finescale rainfall inhomogeneity and is, thus, able to make use of 4-km radar data from the TRMM Precipitation Radar (PR) in order to map regional and seasonal distributions of observed rainfall inhomogeneity in the Tropics. The data are examined to assess the expected errors introduced into climate rainfall records by unresolved changes in rainfall inhomogeneity. Results show that global mean monthly errors introduced by not explicitly accounting for rainfall inhomogeneity do not exceed 0.5% if the beam-filling error is allowed to be a function of rainfall rate and freezing level and does not exceed 2% if a universal beam-filling correction is applied that depends only upon the freezing level. Monthly regional errors can be significantly larger. Over the Indian Ocean, errors as large as 8% were found if the beam-filling correction is allowed to vary with rainfall rate and freezing level while errors of 15% were found if a universal correction is used.

  7. The Effects of Amazon Deforestation on Rainfall

    NASA Technical Reports Server (NTRS)

    Starr, David OC. (Technical Monitor); Negri, Andrew J.; Adler, Robert F.; Surratt, Jason

    2002-01-01

    This study begins with the hypothesis that heavily deforested regions will experience increased surface heating, leading to local circulations that will ultimately enhance the rainfall, or at least, change the pattern of diurnal evolution of rainfall. This would be an important finding because several modeling studies have concluded that widespread deforestation would lead to decreased rainfall. Towards that end rain estimates from a combined GOES infrared/TRMM microwave technique were analyzed with respect to percent forest cover from Landsat data (courtesy of TRFIC at Michigan State University) and GOES visible channel data over a deforested area in Rondonia (southwest Brazil). Five 1" x 1" areas of varying forest cover were examined during the onset of the wet season in Amazonia (Aug-Sept), when the effects of the surface would not be dominated by large-scale synoptic weather patterns. Preliminary results revealed that: maximum rainfall fell in most deforested area; heavily forested areas received the least rainfall; cumulus cloud development initiated at borders; the amplitude of the diurnal cycle of precipitation was a function of th surface cover. Further work will be presented detailing effects of land surface cover on the GOES infrared-measured surface heating, GOES visible observed cumulus development, thunderstorm initiation based on the location of temperature minima in the infrared data, and estimated rainfall and its diurnal cycle from a combined GOES/TRMM technique. Rainfall estimates derived from non-geosynchronous microwave observations (i.e. Goddard Profiling Algorithm, GPROF) will also be examined.

  8. Bistatic radar meteorological satellite

    NASA Technical Reports Server (NTRS)

    Nathanson, F. E.

    1981-01-01

    A technique is discussed that employs a radar transmitter with a moderate size antenna placed in a geosynchronous orbit with either a 0 degree or a low inclination orbit. The reflected signals from the precipitation are then received either on a single beam from a satellite having a beamwidth of about 6 degrees or preferably with a beam that scans the U.S. in a raster pattern with about 0.9 degrees beamwidth. While it would seem that a bistatic system with the transmitter at synchronous altitude and the receivers near the surface would not be a very efficient way of designing a radar system, it is somewhat surprising that the required power and antenna sizes are not that great. Two factors make the meteorological application somewhat more attractive than the bistatic detection of point targets. First, the bistatic reflections of radar signals from precipitation are to a large extent omnidirectional, and while raindrops are spheriods rather than spheres, the relationship of the reflectivity of the rain to rainfall rate can be easily derived. The second reason is that the rain echo signal level is independent of range from a receive only radar, and if the bistatic system works at all, it will work at long ranges.

  9. Flood Nowcasting With Linear Catchment Models, Radar and Kalman Filters

    NASA Astrophysics Data System (ADS)

    Pegram, Geoff; Sinclair, Scott

    A pilot study using real time rainfall data as input to a parsimonious linear distributed flood forecasting model is presented. The aim of the study is to deliver an operational system capable of producing flood forecasts, in real time, for the Mgeni and Mlazi catchments near the city of Durban in South Africa. The forecasts can be made at time steps which are of the order of a fraction of the catchment response time. To this end, the model is formulated in Finite Difference form in an equation similar to an Auto Regressive Moving Average (ARMA) model; it is this formulation which provides the required computational efficiency. The ARMA equation is a discretely coincident form of the State-Space equations that govern the response of an arrangement of linear reservoirs. This results in a functional relationship between the reservoir response con- stants and the ARMA coefficients, which guarantees stationarity of the ARMA model. Input to the model is a combined "Best Estimate" spatial rainfall field, derived from a combination of weather RADAR and Satellite rainfield estimates with point rain- fall given by a network of telemetering raingauges. Several strategies are employed to overcome the uncertainties associated with forecasting. Principle among these are the use of optimal (double Kalman) filtering techniques to update the model states and parameters in response to current streamflow observations and the application of short term forecasting techniques to provide future estimates of the rainfield as input to the model.

  10. Oceans, Climate and Weather

    NSDL National Science Digital Library

    Kimberly Lightle

    2006-01-01

    What is the difference between weather and climate? What do the oceans have to do with them? Weather is the day-to-day state of the atmosphere and its short-term (minutes to weeks) variation. Climate is typically described by the regional patterns of seasonal temperature and precipitation over 30 years. The averages of annual temperature, rainfall, cloud cover, and depth of frost penetration are all typical climate-related statistics. The oceans influence the worlds climate by storing solar energy and distributing it around the planet through currents and atmospheric winds.This publication is all about developing your students understandings of earths oceans and the major effect they have on climate. Understanding and interpreting local weather data and understanding the relationship between weather and climate are important first steps to understanding larger-scale global climate changes. Activities that ask students to collect and analyze local weather data as well as analyze global data can be found in the Lessons and Activities section. Analyzing and interpreting data is a major focus of this publication. Numerous data sets can be found in the Sources for Real Data section. The Background Information section and the article Tomorrows Forecast will help reinforce your own content knowledge.

  11. Space-time organization of debris flows-triggering rainfall: effects on the identification of the rainfall threshold relationships

    NASA Astrophysics Data System (ADS)

    Borga, Marco; Nikolopoulos, Efthymios; Creutin, Jean Dominique; Marra, Francesco

    2015-04-01

    Debris flow occurrence is generally forecasted by means of empirical rainfall depth-duration thresholds which are often derived based on rain gauge observations (Guzzetti et al., 2008). Rainfall sampling errors, related to the sparse nature of raingauge data, lead to underestimation of the intensity-duration thresholds (Nikolopoulos et al., 2014, Nikolopoulos et al., 2015). This underestimation may be large when debris flows are triggered by convective rainfall events, characterized by limited spatial extent, turning into less efficient forecasts of debris flow occurrence. This work investigates the spatial and temporal structure of rainfall patterns and its effects on the derived rainfall threshold relationships using high-resolution, carefully corrected radar data for 82 debris flows events occurred in the eastern Italian Alps. We analyze the spatial organization of rainfall depths relative to the rainfall occurred over the debris flows initiation point using the distance from it as the main coordinate observing that, on average, debris flows initiation points are characterized by a maximum in the rainfall depth field. We investigate the relationship between spatial organization and duration of rainfall pointing out that the rainfall underestimation is larger for the shorter durations and increases regularly as the distance between rainfall measurement location and debris flow initiation point increases. We introduce an analytical framework that explains how the combination of the mean rainfall depth spatial pattern and its relationship with rainfall duration causes the bias observed in the raingauge-based thresholds. The consistency of this analytical framework is proved by using a Monte Carlo sampling of radar rainfall fields. References Guzzetti, F., Peruccacci, S., Rossi, M., Stark, C.P., 2008. The rainfall intensity-duration control of shallow landslides and debris flows: an update. Landslides 5, 3-17, 10.1007/s10346-625 007-0112-1 Nikolopoulos, E.I., S. Crema, L. Marchi, F. Marra, F. Guzzetti, M. Borga, 2014: Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence. Geomorphology, 221 (2014), 286-297. DOI: 10.1016/j.geomorph.2014.06.015 Nikolopoulos, E.I., F. Marra, J.D. Creutin, M. Borga, 2015: Estimation of debris flow triggering rainfall: influence of rain gauge density and interpolation methods. Geomorphology, conditionally accepted.

  12. Latent Heating Retrievals Using the TRMM Precipitation Radar: A Multi-Seasonal Study

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, S.; Meneghini, R.; Halverson, J.; Johnson, R.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. Present largescale weather and climate models can simulate latent heat release only crudely, thus reducing their confidence in predictions on both global and regional scales. This paper represents the first attempt to use NASA Tropical Rainfall Measuring Mission (TRMM) rainfall information to estimate the four-dimensional structure of global monthly latent heating profiles over the global tropics from December 1997 to October 2000. The Goddard Convective-Stratiform. Heating (CSH) algorithm and TRMM precipitation radar data are used for this study. We will examine and compare the latent heating structures between 1997-1998 (winter) ENSO and 1998-2000 (non-ENSO). We will also examine over the tropics. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental; Indian oceans vs west Pacific; Africa vs S. America) will be also examined and compared. In addition, we will examine the relationship between latent heating (max heating level) and SST. The period of interest also coincides with several TRMM field campaigns that recently occurred over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and in the central Pacific in 1999 (KWAJEX). Sounding diagnosed Q1 budgets from these experiments could provide a means of validating the retrieved profiles of latent heating from the CSH algorithm.

  13. Current status of Dual Ka-band radar field campaign in Japan for GPM/DPR mission

    NASA Astrophysics Data System (ADS)

    Kaneko, Yuki; Nakagawa, Katsuhiro; Nishikawa, Masanori; Nakamura, Kenji; Fujiyoshi, Yasushi; Hanado, Hiroshi; Minda, Haruya; Yamamoto, Kazuhide; Oki, Riko; Furukawa, Kinji

    2013-04-01

    The Global Precipitation Measurement (GPM) mission is an expanded follow-on mission to TRMM (Tropical Rainfall Measuring Mission) and a GPM core satellite will carry dual frequency precipitation radar (DPR) and a GPM Microwave Imager on board. The DPR, which is being developed by National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA), consists of two radars; Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The DPR is expected to advance precipitation science by expanding the coverage of observations to higher latitudes than those of the TRMM/PR, measuring snow and light rain by the KaPR, and providing drop size distribution information based on the differential attenuation of echoes at two frequencies. In order to secure the quality of precipitation estimates, ground validation (GV) of satellite data and retrieval algorithms is essential. Since end-to-end comparisons between instantaneous precipitation data observed by satellite and ground-based instruments is not enough to improve the algorithms. The error of various physical parameters in the precipitation retrieval algorithms (e.g. attenuation factor, drop size distribution, terminal velocity, density of the snow particles, etc.) will be estimated by the comparison with the ground-based observation data. A dual Ka-band radar system is developed by the JAXA for the GPM/DPR algorithm development. The dual Ka-radar system which consists of two identical Ka-band radars can measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those parameters are important particularly for snow measurement. Using the dual Ka-radar system along with other instruments, such as a polarimetric precipitation radar, a wind-profiler radar, ground-based precipitation measurement systems, the uncertainties of the parameters in the DPR algorithm can be reduced. The verification of improvement of rain retrieval with the DPR algorithm is also included as an objective. Observations using the dual Ka-radar system were performed in Okinawa Island, in Tsukuba, over the slope of Mt. Fuji, in Nagaoka, and in Sapporo, from 2011 to 2013. In Okinawa Island, the performance of the measurement has been confirmed by rain observation. In Tsukuba, one radar was directed in vertical and the other was in slant direction. By this configuration, total attenuation in the melting layer was estimated. The objective of the Mt. Fuji experiment was to observe the melting layer. The X-band polarimetric radar was simultaneously operated. Unfortunately, the melting layer did not come in between the two radars due to warm weather. In Nagaoka, much data on the wet snow was obtained. In Sapporo, dry snow has been observed by dual Ka-radar with meteorological instruments and other appliances. Through those experiments the main results are the k - Ze relationships on various precipitation types. The feasibility of total attenuation in melting layer has been studied. Different k - Ze relationships have been obtained in snow observations. The vertical variations of rainfall are also analyzed for the DPR algorithm development.

  14. Spatial and Seasonal Variation of Rain Profiles over Asia Observed by Spaceborne Precipitation Radar

    Microsoft Academic Search

    Masafumi Hirose; Kenji Nakamura

    2002-01-01

    The Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) has made it possible for the first time to evaluate global characteristics of vertical structures of rainfall over monsoon Asia. This study is intended to depict features of seasonal variations of the vertical gradient of rainfall rate using TRMM PR data from 1998 to 2000.The features of downward decreasing (DD) or

  15. Using Conditional Analysis to Investigate Spatial and Temporal patterns in Upland Rainfall

    NASA Astrophysics Data System (ADS)

    Sakamoto Ferranti, Emma Jayne; Whyatt, James Duncan; Timmis, Roger James

    2010-05-01

    The seasonality and characteristics of rainfall in the UK are altering under a changing climate. Summer rainfall is generally decreasing whereas winter rainfall is increasing, particularly in northern and western areas (Maraun et al., 2008) and recent research suggests these rainfall increases are amplified in upland areas (Burt and Ferranti, 2010). Conditional analysis has been used to investigate these rainfall patterns in Cumbria, an upland area in northwest England. Cumbria was selected as an example of a topographically diverse mid-latitude region that has a predominately maritime and westerly-defined climate. Moreover it has a dense network of more than 400 rain gauges that have operated for periods between 1900 and present day. Cumbria has experienced unprecedented flooding in the past decade and understanding the spatial and temporal changes in this and other upland regions is important for water resource and ecosystem management. The conditional analysis method examines the spatial and temporal variations in rainfall under different synoptic conditions and in different geographic sub-regions (Ferranti et al., 2009). A daily synoptic typing scheme, the Lamb Weather Catalogue, was applied to classify rainfall into different weather types, for example: south-westerly, westerly, easterly or cyclonic. Topographic descriptors developed using GIS were used to classify rain gauges into 6 directionally-dependant geographic sub-regions: coastal, windward-lowland, windward-upland, leeward-upland, leeward-lowland, secondary upland. Combining these classification methods enabled seasonal rainfall climatologies to be produced for specific weather types and sub-regions. Winter rainfall climatologies were constructed for all 6 sub-regions for 3 weather types - south-westerly (SW), westerly (W), and cyclonic (C); these weather types contribute more than 50% of total winter rainfall. The frequency of wet-days (>0.3mm), the total winter rainfall and the average wet day rainfall amount were analysed for each rainfall sub-region and weather type from 1961-2007 (Ferranti et al., 2010). The conditional analysis showed total rainfall under SW and W weather types to be increasing, with the greatest increases observed in the upland sub-regions. The increase in total SW rainfall is driven by a greater occurrence of SW rain days, and there has been little change to the average wet-day rainfall amount. The increase in total W rainfall is driven in part by an increase in the frequency of wet-days, but more significantly by an increase in the average wet-day rainfall amount. In contrast, total rainfall under C weather types has decreased. Further analysis will investigate how spring, summer and autumn rainfall climatologies have changed for the different weather types and sub-regions. Conditional analysis that combines GIS and synoptic climatology provides greater insights into the processes underlying readily available meteorological data. Dissecting Cumbrian rainfall data under different synoptic and geographic conditions showed the observed changes in winter rainfall are not uniform for the different weather types, nor for the different geographic sub-regions. These intricate details are often lost during coarser resolution analysis, and conditional analysis will provide a detailed synopsis of Cumbrian rainfall processes against which Regional Climate Model (RCM) performance can be tested. Conventionally RCMs try to simulate composite rainfall over many different weather types and sub-regions and by undertaking conditional validation the model performance for individual processes can be tested. This will help to target improvements in model performance, and ultimately lead to better simulation of rainfall in areas of complex topography. BURT, T. P. & FERRANTI, E. J. S. (2010) Changing patterns of heavy rainfall in upland areas: a case study from northern England. Atmospheric Environment, [in review]. FERRANTI, E. J. S., WHYATT, J. D. & TIMMIS, R. J. (2009) Development and application of topographic descriptors for conditional a

  16. Multi-Antenna Radar Systems for Doppler Rain Measurements

    NASA Technical Reports Server (NTRS)

    Durden, Stephen; Tanelli, Simone; Siqueira, Paul

    2007-01-01

    Use of multiple-antenna radar systems aboard moving high-altitude platforms has been proposed for measuring rainfall. The basic principle of the proposed systems is a variant of that of along-track interferometric synthetic-aperture radar systems used previously to measure ocean waves and currents.

  17. a Regional Study of Seasonal Rainfall Conditions in the Sudan

    NASA Astrophysics Data System (ADS)

    El Seed, Abdel Malik Gasm

    Available from UMI in association with The British Library. This thesis is primarily a regional climatological study of some spatial and temporal rainfall characteristics, with a special emphasis being made on quantitative analysis of the wet season rains over the Sudan. The study area has been objectively classified into five main "rainfall regions" on the basis of wet season duration and timing at 60 observing stations. Also a regionalisation derived from two multivariate techniques is compared and critically discussed. The spatial distributions of mean wet and dry season rainfall over individual regions, are described and explained by reference to the main weather systems and topographic features using the method of trend surface analysis. Rainfall variability has been quantified by the coefficient of variation index and analysed in a similar way to that of rainfall distribution. The results have shown an inverse relationship between variability indices and mean rainfall amounts. In relation to the study of variability, an assessment of rainfall probability and reliability has been discussed with reference to certain critical rainfall amounts and by applying the concept of binomial frequency distribution for critical time periods. The spatial distribution of mean rain days tends to portray a similar pattern to that of the mean rainfall. This apparent relationship is confirmed by the highly significant correlation coefficients between the two parameters. The relation between mean rainfall and daily rainfall intensity is not always a direct one, since wetter areas are mostly associated with increased frequency of rain days rather than greater rainfall intensities. Daily rainfall analysis has also revealed that the probability distributions of wet and dry spells of various sequence lengths can be mathematically derived from a Markov chain model and these were found to fit the actual daily data closely. Finally, the contributions of various atmospheric factors to the rainfall amounts are determined by applying multiple regression analysis. The provision of partial regression equations also permits an estimate of rainfall with a reasonable degree of accuracy for any place in the Sudan.

  18. P8R.16 SPATIAL CLASSIFICATION OF PRECIPITATION FROM OPERATIONAL RADAR DATA

    E-print Network

    Stoffelen, Ad

    P8R.16 SPATIAL CLASSIFICATION OF PRECIPITATION FROM OPERATIONAL RADAR DATA C algorithms derived from operational radar data as well as to facilitate the study of spatial and temporal variability of rainfall. Using the Cband radar data of the KNMI at De Bilt (the Netherlands) several

  19. Uncertainties in Oceanic Radar Rain Maps at Kwajalein and Implications for Satellite Validation

    Microsoft Academic Search

    Robert A. Houze Jr; Stacy Brodzik; Courtney Schumacher; Sandra E. Yuter; Christopher R. Williams

    2004-01-01

    The Kwajalein, Marshall Islands, Tropical Rainfall Measuring Mission (TRMM) ground validation radar has provided a multiyear three-dimensional radar dataset at an oceanic site. Extensive rain gauge networks are not feasible over the ocean and, hence, are not available to aid in calibrating the radar or determining a conversion from reflectivity to rain rate. This paper describes methods used to ensure

  20. Simulation Results Of An Improved Rain-rate Retrieval Algorithm For A Spaceborne Rain Radar

    Microsoft Academic Search

    Duc C. Kieu; Richard K. Moore

    1992-01-01

    A satellite rain-measuring radar will fly on the Tropical Rainfall Measuring Mission (TRMM), and plans are underway for other satellite rain radars. The radars will allow estimation of the vertical profile of rain rates, from which the profile of latent heat release can be estimated. Latent heat release has been considered as an important factor in determining the structure and

  1. AN AUTOMATED METHOD FOR DETECTING PRECIPITATION AND CELL TYPE FROM RADAR PRODUCTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is of interest for many purposes, including nowcasting, to evaluate the structure of radar images in an effort to produce more accurate estimates of rainfall totals from radar data. Although subjective analysis can reliably determine the structure of radar imagery, computational techniques exist ...

  2. The NASA Dual-Frequency Dual-Polarized Doppler Radar (D3R) System For GPM Ground Validation

    NASA Astrophysics Data System (ADS)

    Chandrasekar, V.; Schwaller, Mathew; Vega, Manuel; Carswell, James; Vijay Mishra, Kumar; Nguyen, Cuong; Meneghini, Robert; Peterson, Walt

    2010-05-01

    Following on the successful introduction of single-frequency (Ku-Band) weather radar onboard the Tropical Rain Measuring Mission (TRMM) satellite in 1997, the Global Precipitation Measurement (GPM) mission attempts to advance further the goal of making global scale precipitation observations by deploying the next generation of satellite-borne weather radars. The GPM satellite will carry a Ka-Ku band Dual-frequency Precipitation Radar (DPR) that can make measurements of parameters directly related to the microphysics of precipitation (such as raindrop size distribution). The Dual-Frequency Dual-Polarized Doppler Radar (D3R) is a ground validation radar, as a part of the GPM Ground Validation (GV) program, to enable both physical validation support in terms of understanding the microphysical description of the observations as well as algorithm retrieval implications. This paper provides a scientific and technical overview of the D3R system as well as major challenges. The preferred frequency bands of operation for precipitation surveillance in ground radar systems have been nearly non-attenuating frequencies (such as S-, C-band) or short-range measurements of attenuating frequencies (as in X band). However, it is not practical to use traditional ground radar frequencies for precipitation observations in space-borne radars. The GPM mission has embarked on a dual-frequency approach at Ku- and Ka-band for characterizing precipitation. Moving to higher frequencies to observe precipitation though has its own challenges namely, attenuation due to precipitation and reduced Doppler velocity Nyquist limits. Ground radar measurements enjoy the advantage of coincident microphysical observations available to interpret radar signatures but they are currently unavailable at Ku- and Ka-band. An important broader science goal of the NASA D3R is to enhance the database of dual-frequency radar observations on the ground, in conjunction with existing observations, in order to provide a dataset for physical validation basis. Another major advantage of the ground radar observations is the ability to use dual-polarization techniques to yield enhanced microphysical characterization similar to what has been done at lower frequencies. In addition, self-consistency of dual-polarization and dual-frequency observations presents an enhanced level of interpretation, while also providing independent rainfall estimates on the ground. With the ground-based D3R, an independent estimation of hydrometeor classification and drop size distribution retrievals can be done to understand the error structure of retrievals. The dual-frequency ground-based radar provides for various options, including polarimetry and Doppler capabilities. Hence, the name D3R or Dual-frequency Dual-polarized Doppler Radar. Another important engineering aspect of a dual-frequency system is the level of "integration". This can range from a design where two separate radar units operate independently to the one that employs a common reference system for dual-transmitters on a single dual-frequency aperture. The first generation version of the D3R falls somewhere in the middle, i.e., a common platform transmitter illuminating two distinct but aligned antennas. Most of the engineering challenges stem from making precipitation measurements on the ground at a highly attenuating frequency. In order to support the development, extensive numerical evaluations have been carried out to document the extinction statistics of propagation through precipitation. One of the novel aspects of this system is that it employs a solid-state transceiver which supports the deployment in different climactic locations. Thirdly, the dual-frequency dual-polarization operation at higher frequencies involves non-Rayleigh scattering mechanisms and presents different precipitation signatures compared to the conventional S- or C- band observations. The expected observations for this radar based on such scattering and precipitation models are also presented in this paper.

  3. Robust Estimator for Annual Rainfall Erosivity in Korea

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Song, H. K.; Shin, H.; Heo, J. H.

    2014-12-01

    This study performed to identify appropriate parameters for estimating annual rainfall erosivity in Korea. Nine types of rainfall parameters for 28 weather stations over 20 years were used in this study. Correlation analysis between calculated rainfall erosivities and nine parameters in 28 stations were conducted to find the proper estimator of annual rainfall erosivity. The results showed a significant positive relationships between "sum of monthly precipitation for 2~5 months (called Modified IAS index)" and annual rainfall erosivity in all 28 stations with a 99% confidence. The second most strongly correlated parameter was annual precipitation; 27 of 28 stations had a siginificant relationship with 99% confidence level. The study found out "Modified IAS index" was the best robust estimator for annual rainfall erosivity more than annual precipitation in Korea.

  4. Report on the Radar/PIREP Cloud Top Discrepancy Study

    NASA Technical Reports Server (NTRS)

    Wheeler, Mark M.

    1997-01-01

    This report documents the results of the Applied Meteorology Unit's (AMU) investigation of inconsistencies between pilot reported cloud top heights and weather radar indicated echo top heights (assumed to be cloud tops) as identified by the 45 Weather Squadron (45WS). The objective for this study is to document and understand the differences in echo top characteristics as displayed on both the WSR-88D and WSR-74C radars and cloud top heights reported by the contract weather aircraft in support of space launch operations at Cape Canaveral Air Station (CCAS), Florida. These inconsistencies are of operational concern since various Launch Commit Criteria (LCC) and Flight Rules (FR) in part describe safe and unsafe conditions as a function of cloud thickness. Some background radar information was presented. Scan strategies for the WSR-74C and WSR-88D were reviewed along with a description of normal radar beam propagation influenced by the Effective Earth Radius Model. Atmospheric conditions prior to and leading up to both launch operations were detailed. Through the analysis of rawinsonde and radar data, atmospheric refraction or bending of the radar beam was identified as the cause of the discrepancies between reported cloud top heights by the contract weather aircraft and those as identified by both radars. The atmospheric refraction caused the radar beam to be further bent toward the Earth than normal. This radar beam bending causes the radar target to be displayed erroneously, with higher cloud top heights and a very blocky or skewed appearance.

  5. Role of Satellite Rainfall Information in Improving Understanding of the Dynamical Link Between the Tropics and Extratropics Prospects of Improved Forecasts of Weather and Short-Term Climate Variability on Sub-Seasonal Time Scales

    NASA Technical Reports Server (NTRS)

    Hou, Arthur Y.

    2002-01-01

    The tropics and extratropics are two dynamically distinct regimes. The coupling between these two regimes often defies simple analytical treatment. Progress in understanding of the dynamical interaction between the tropics and extratropics relies on better observational descriptions to guide theoretical development. However, global analyses currently contain significant errors in primary hydrological variables such as precipitation, evaporation, moisture, and clouds, especially in the tropics. Tropical analyses have been shown to be sensitive to parameterized precipitation processes, which are less than perfect, leading to order-one discrepancies between estimates produced by different data assimilation systems. One strategy for improvement is to assimilate rainfall observations to constrain the analysis and reduce uncertainties in variables physically linked to precipitation. At the Data Assimilation Office at the NASA Goddard Space Flight Center, we have been exploring the use of tropical rain rates derived from the TRMM Microwave Imager (TMI) and the Special Sensor Microwave/ Imager (SSM/I) instruments in global data assimilation. Results show that assimilating these data improves not only rainfall and moisture fields but also related climate parameters such as clouds and radiation, as well as the large-scale circulation and short-range forecasts. These studies suggest that assimilation of microwave rainfall observations from space has the potential to significantly improve the quality of 4-D assimilated datasets for climate investigations (Hou et al. 2001). In the next few years, there will be a gradual increase in microwave rain products available from operational and research satellites, culminating to a target constellation of 9 satellites to provide global rain measurements every 3 hours with the proposed Global Precipitation Measurement (GPM) mission in 2007. Continued improvements in assimilation methodology, rainfall error estimates, and model parameterizations are needed to ensure that we derive maximum benefits from these observations.

  6. Weather Report

    NSDL National Science Digital Library

    This printable weather report is designed to help students easily note a field site's important meteorological details. The one-page PDF form asks for the following information: date, temperature, precipitation, weather type, and wind speed (based on environmental clues).

  7. Winter Weather

    MedlinePLUS

    ... About CDC.gov . Natural Disasters and Severe Weather Earthquakes Being Prepared Emergency Supplies Home Hazards Indoor Safety ... What's New A - Z Index Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis Volcanoes ...

  8. Short Wavelength Technology and the Potential for Distributed Networks of Short-Range Radar Systems

    E-print Network

    Cruz-Pol, Sandra L.

    of the troposphere. Data collected by these sensors serve as critical inputs to weather-related decision making, tracking, and predicting algorithms) that diagnose weather conditions in real-time and re-steer radar beams

  9. Weather Talk

    NSDL National Science Digital Library

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

  10. Copula-based assimilation of radar and gauge information to derive bias corrected precipitation fields

    NASA Astrophysics Data System (ADS)

    Vogl, S.; Laux, P.; Qiu, W.; Mao, G.; Kunstmann, H.

    2012-01-01

    This study addresses the problem of combining radar information and gauge measurements. Gauge measurements are the best available source of absolute rainfall intensity albeit their spatial availability is limited. Precipitation information obtained by radar mimics well the spatial patterns but is biased for their absolute values. In this study Copula models are used to describe the dependence structure between gauge observations and rainfall derived from radar reflectivity at the corresponding grid cells. Only the positive pairs (radar > 0, gauge > 0) are considered. As not each grid cell can be assigned to one gauge, the integration of point information, i.e. gauge rainfall intensities, is achieved by considering the structure and the strength of dependence between the radar pixels and all the gauges within the radar image. Two different approaches namely Maximum Theta and Multiple Theta are presented. They finally allow for generating precipitation fields which mimic the spatial patterns of the radar fields and correct them for biases in their absolute rainfall intensities. The performance of the approach, which can be seen as a bias-correction for radar scenes, is demonstrated for the Bavarian Alps. The bias-corrected rainfall fields are compared to a field of interpolated gauge values (Ordinary Kriging) and are validated with the available gauge measurements. The simulated precipitation fields are compared to an operationally corrected radar precipitation field (RADOLAN). This comparison of the Copula-based approach and RADOLAN by different validation measures indicates that the Copula-based method successfully corrects for errors in the radar precipitation.

  11. Copula-based assimilation of radar and gauge information to derive bias corrected precipitation fields

    NASA Astrophysics Data System (ADS)

    Vogl, S.; Laux, P.; Qiu, W.; Mao, G.; Kunstmann, H.

    2012-04-01

    This study addresses the problem of combining radar information and gauge measurements. Gauge measurements are the best available source of absolute rainfall intensity albeit their spatial availability is limited. Precipitation information obtained by radar mimics well the spatial patterns but is biased for their absolute values. In this study Copula models are used to describe the dependence structure between gauge observations and rainfall derived from radar reflectivity at the corresponding grid cells. Only the positive pairs (radar > 0, gauge > 0) are considered. As not each grid cell can be assigned to one gauge, the integration of point information, i.e. gauge rainfall intensities, is achieved by considering the structure and the strength of dependence between the radar pixels and all the gauges within the radar image. Two different approaches namely Maximum Theta and Multiple Theta are presented. They finally allow for generating precipitation fields which mimic the spatial patterns of the radar fields and correct them for biases in their absolute rainfall intensities. The performance of the approach, which can be seen as a bias-correction for radar scenes, is demonstrated for the Bavarian Alps. The bias-corrected rainfall fields are compared to a field of interpolated gauge values (Ordinary Kriging) and are validated with the available gauge measurements. The simulated precipitation fields are compared to an operationally corrected radar precipitation field (RADOLAN). This comparison of the Copula-based approach and RADOLAN by different validation measures indicates that the Copula-based method successfully corrects for errors in the radar precipitation.

  12. The DEFENSE (debris Flows triggEred by storms - nowcasting system): An early warning system for torrential processes by radar storm tracking using a Geographic Information System (GIS)

    NASA Astrophysics Data System (ADS)

    Tiranti, Davide; Cremonini, Roberto; Marco, Federica; Gaeta, Armando Riccardo; Barbero, Secondo

    2014-09-01

    Debris flows, responsible for economic losses and occasionally casualties in the alpine region, are mainly triggered by heavy rains characterized by hourly peaks of varying intensity, depending on the features of the basin under consideration. By integrating a recent classification of alpine basins with the radar storm tracking method, an innovative early warning system called DEFENSE (DEbris Flows triggEred by storms - Nowcasting SystEm) was developed using a Geographical Information System (GIS). Alpine catchments were classified into three main classes based on the weathering capacity of the bedrock into clay or clay-like minerals, the amount of which, in unconsolidated material, directly influences the debris flow rheology, and thus the sedimentary processes, the alluvial fan architecture, as well as the triggering frequency and seasonal occurrence probability of debris flows. Storms were identified and tracked by processing weather radar observations; subsequently, rainfall intensities and storm severity were estimated over each classified basin. Due to rainfall threshold values determined for each basin class, based on statistical analysis of historical records, an automatic corresponding warning could be issued to municipalities.

  13. World Weather

    NSDL National Science Digital Library

    Elias, Jaume Sanchez

    2014-02-20

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

  14. Weather Watcher

    NSDL National Science Digital Library

    Singer, Mike

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

  15. Analysis of rainfall characteristics of the Madden–Julian oscillation using TRMM satellite data

    Microsoft Academic Search

    Juntaro Morita; Yukari N. Takayabu; Shoichi Shige; Yasumasa Kodama

    2006-01-01

    Rainfall characteristics of the Madden–Julian oscillation (MJO) are analyzed primarily using tropical rainfall measuring mission (TRMM) precipitation radar (PR), TRMM microwave imager (TMI) and lighting imaging sensor (LIS) data. Latent heating structure is also examined using latent heating data estimated with the spectral latent heating (SLH) algorithm.The zonal structure, time evolution, and characteristic stages of the MJO precipitation system are

  16. Rainfall-River Forecasting

    E-print Network

    US Army Corps of Engineers

    Rainfall-River Forecasting: Overview of NOAA's Role, Responsibilities, and Services Rainfall-River Services Division NWS Headquarters Steve Buan Service Coordination Hydrologist NWS North Central River Forecast Center Rainfall-River Forecasting Joint Summit II October 19, 2008 St. Paul, Minnesota 1 #12

  17. Global Precipitation Measurement Program and the Development of Dual-Frequency Precipitation Radar

    NASA Technical Reports Server (NTRS)

    Iguchi, Toshio; Oki, Riko; Smith, Eric A.; Furuhama, Yoji

    2002-01-01

    The Global Precipitation Measurement (GPM) program is a mission to measure precipitation from space, and is a similar but much expanded mission of the Tropical Rainfall Measuring Mission. Its scope is not limited to scientific research, but includes practical and operational applications such as weather forecasting and water resource management. To meet the requirements of operational use, the GPM uses multiple low-orbiting satellites to increase the sampling frequency and to create three-hourly global rain maps that will be delivered to the world in quasi-real time. A dual-frequency radar (DPR) will be installed on the primary satellite that plays an important role in the whole mission. The DPR will realize measurement of precipitation with high sensitivity, high precision and high resolutions. This paper describes an outline of the GPM program, its issues and the roles and development of the DPR.

  18. Estimation of the fractional coverage of rainfall in climate models

    SciTech Connect

    Eltahir, E.A.B.; Bras, R.L. (Massachusetts Institute of Technology, Cambridge (United States))

    1993-04-01

    The fraction of the grid cell area covered by rainfall, [mu], is a very important parameter in the descriptions of land surface hydrology in climate models. A simple procedure is presented for estimating this fraction, on extensive observations of storm areas and rainfall volumes. It is often observed that storm area and rainfall volume are linearly related. This relation is utilized in rainfall measurement to compute rainfall volume from radar observations of the storm area. The authors suggest that the same relation be used to compute the storm area from the volume of rainfall simulated by a climate model. A formula is developed for computing [mu], which describes the dependence of the fractional coverage of rainfall on the season of the year, the geographical region, rainfall volume, spatial resolution of the model, and the temporal resolution of the model. The new formula is applied in computing [mu] over the Amazon region. Significant temporal variability in the fractional coverage of rainfall is demonstrated. The implications of this variability for the modeling of land surface hydrology in climate models are discussed. 16 refs., 3 figs., 1 tab.

  19. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    NASA Astrophysics Data System (ADS)

    Petersen, Walt; Krajewski, Witek; Wolff, David; Gatlin, Patrick

    2015-04-01

    The Global Precipitation Measurement (GPM) Mission Iowa Flood Studies (IFloodS) campaign was conducted in central and northeastern Iowa during the months of April-June, 2013. Specific science objectives for IFloodS included quantification of uncertainties in satellite and ground-based estimates of precipitation, 4-D characterization of precipitation physical processes and associated parameters (e.g., size distributions, water contents, types, structure etc.), assessment of the impact of precipitation estimation uncertainty and physical processes on hydrologic predictive skill, and refinement of field observations and data analysis approaches as they pertain to future GPM integrated hydrologic validation and related field studies. In addition to field campaign archival of raw and processed satellite data (including precipitation products), key ground-based platforms such as the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms, and a large network of 2D Video and Parsivel disdrometers were deployed. In something of a canonical approach, the radar (NPOL in particular), gauge and disdrometer observational assets were deployed to create a consistent high-quality distributed (time and space sampling) radar-based ground "reference" rainfall dataset, with known uncertainties, that could be used for assessing the satellite-based precipitation products at a range of space/time scales. Subsequently, the impact of uncertainties in the satellite products could be evaluated relative to the ground-benchmark in coupled weather, land-surface and distributed hydrologic modeling frameworks as related to flood prediction. Relative to establishing the ground-based "benchmark", numerous avenues were pursued in the making and verification of IFloodS "reference" dual-polarimetric radar-based rain maps, and this study documents the process and results as they pertain specifically to efforts using the NPOL radar dataset. The initial portions of the "process" involved dual-polarimetric quality control procedures which employed standard phase and correlation-based approaches to removal of clutter and non-meteorological echo. Calculation of a scale-adaptive KDP was accomplished using the method of Wang and Chandrasekar (2009; J. Atmos. Oceanic Tech.). A dual-polarimetric blockage algorithm based on Lang et al. (2009; J. Atmos. Oceanic Tech.) was then implemented to correct radar reflectivity and differential reflectivity at low elevation angles. Next, hydrometeor identification algorithms were run to identify liquid and ice hydrometeors. After the quality control and data preparation steps were completed several different dual-polarimetric rain estimation algorithms were employed to estimate rainfall rates using rainfall scans collected approximately every two to three minutes throughout the campaign. These algorithms included a polarimetrically-tuned Z-R algorithm that adjusts for drop oscillations (via Bringi et al., 2004, J. Atmos. Oceanic Tech.), and several different hybrid polarimetric variable approaches, including one that made use of parameters tuned to IFloodS 2D Video Disdrometer measurements. Finally, a hybrid scan algorithm was designed to merge the rain rate estimates from multiple low level elevation angle scans (where blockages could not be appropriately corrected) in order to create individual low-level rain maps. Individual rain maps at each time step were subsequently accumulated over multiple time scales for comparison to gauge network data. The comparison results and overall error character depended strongly on rain event type, polarimetric estimator applied, and range from the radar. We will present the outcome of these comparisons and their impact on constructing composited "reference" rainfall maps at select time and space scales.

  20. Monitoring Niger River Floods from satellite Rainfall Estimates : overall skill and rainfall uncertainty propagation.

    NASA Astrophysics Data System (ADS)

    Gosset, Marielle; Casse, Claire; Peugeot, christophe; boone, aaron; pedinotti, vanessa

    2015-04-01

    Global measurement of rainfall offers new opportunity for hydrological monitoring, especially for some of the largest Tropical river where the rain gauge network is sparse and radar is not available. Member of the GPM constellation, the new French-Indian satellite Mission Megha-Tropiques (MT) dedicated to the water and energy budget in the tropical atmosphere contributes to a better monitoring of rainfall in the inter-tropical zone. As part of this mission, research is developed on the use of satellite rainfall products for hydrological research or operational application such as flood monitoring. A key issue for such applications is how to account for rainfall products biases and uncertainties, and how to propagate them into the end user models ? Another important question is how to choose the best space-time resolution for the rainfall forcing, given that both model performances and rain-product uncertainties are resolution dependent. This paper analyses the potential of satellite rainfall products combined with hydrological modeling to monitor the Niger river floods in the city of Niamey, Niger. A dramatic increase of these floods has been observed in the last decades. The study focuses on the 125000 km2 area in the vicinity of Niamey, where local runoff is responsible for the most extreme floods recorded in recent years. Several rainfall products are tested as forcing to the SURFEX-TRIP hydrological simulations. Differences in terms of rainfall amount, number of rainy days, spatial extension of the rainfall events and frequency distribution of the rain rates are found among the products. Their impacts on the simulated outflow is analyzed. The simulations based on the Real time estimates produce an excess in the discharge. For flood prediction, the problem can be overcome by a prior adjustment of the products - as done here with probability matching - or by analysing the simulated discharge in terms of percentile or anomaly. All tested products exhibit some skills in detecting the relatively heavy rainfall that preceded the flood and in predicting that the 95th percentile of the discharge (i.e. the flood alert level in Niamey) will be exceeded. One outcome of the work is to show how different types of satellite information can be relevant and their scales complementing each-other for tropical hydrology. The red flood of the Niger river in Niamey is a good example of these scale complementarity. Satellite altimetry is needed to monitor the low frequency variation of the Niger outflow associated with early season rainfall far ahead of Niamey ; while high resolution satellite rainfall products are needed to model the fast response to the rainfall occurring during the heart of the monsoon season near Niamey.