Precipitation estimation by weather radars in Alaska is challenging. In this study, we investigat... more Precipitation estimation by weather radars in Alaska is challenging. In this study, we investigate National Weather Service (NWS) precipitation products that are produced from the seven NEXRAD radar sites in Alaska. The NWS precipitation processing subsystem generates stages of data at each NEXRAD site which are then input to the weather forecast office to generate a regionwide precipitation product. Data from the NEXRAD sites and the operational rain gauges in the weather forecast region are used to produce this regionwide product that is then sent to the National Centers for Environmental Prediction (NCEP) to be included in the NCEP Stage IV distribution. The NCEP Stage IV product for Alaska has been available since 2017. We use the United States Climate Reference Network (USCRN) data from Alaska to compare to the NCEP Stage IV data. Given that the USCRN can be used in the production of the NCEP Stage IV data for Alaska, we also used the NEXRAD Digital Precipitation Array (DPA) th...
We use a suite of quantitative precipitation estimates (QPEs) derived from satellite, radar, and ... more We use a suite of quantitative precipitation estimates (QPEs) derived from satellite, radar, and surface observations to derive precipitation characteristics over the contiguous United States (CONUS) for the period 2002–2012. This comparison effort includes satellite multi-sensor data sets (bias-adjusted TMPA 3B42, near-real-time 3B42RT), radar estimates (NCEP Stage IV), and rain gauge observations. Remotely sensed precipitation data sets are compared with surface observations from the Global Historical Climatology Network-Daily (GHCN-D) and from the PRISM (Parameter-elevation Regressions on Independent Slopes Model). The comparisons are performed at the annual, seasonal, and daily scales over the River Forecast Centers (RFCs) for CONUS. Annual average rain rates present a satisfying agreement with GHCN-D for all products over CONUS (±6%). However, differences at the RFC are more important in particular for near-real-time 3B42RT precipitation estimates (−33 to +49%). At annual and s...
Proquest Dissertations and Theses Thesis the University of Iowa 2003 Publication Number Aai3097561 Isbn 9780496451746 Source Dissertation Abstracts International Volume 64 07 Section B Page 3157 152 P, 2003
The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation esti... more The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation estimates (QPEs) are used in many studies for intercomparisons including those for satellite QPEs. An overview of the National Weather Service precipitation processing system is provided here so as to set the stage IV product in context and to provide users with some knowledge as to how it is developed. Then, an assessment of the stage IV product over the period 2002–12 is provided. The assessment shows that the stage IV product can be useful for conditional comparisons of moderate-to-heavy rainfall for select seasons and locations. When evaluating the product at the daily scale, there are many discontinuities due to the operational processing at the radar site as well as discontinuities due to the merging of data from different River Forecast Centers (RFCs) that use much different processing algorithms for generating their precipitation estimates. An assessment of the daily precipitation es...
The precipitation climatology of the Southeastern United States and the Carolinas region in parti... more The precipitation climatology of the Southeastern United States and the Carolinas region in particular spans a very broad spectrum of precipitation regimes. A warm season that is characterized by isolated thunderstorms, squall line mesoscale convective systems, and tropical cyclones, and a winter season characterized by widespread frontal rain, ice, and snowfall. Each of these types of precipitation system impacts regional hydrology in very different ways, and are associated with a large variety of natural hazards. In this work, we propose to develop a comprehensive climatology of precipitation using a multi-sensor approach (ground based: Q2, rain gauges; and remotely sensed: TRMM PR) with the goal to derive hydrological characteristics of precipitation. The goal of this study is two-fold. In the first aspect of this work we will derive diurnal, seasonal, and yearly trends as it concern the temporal frequency and spatial distribution of precipitation patterns with a particular focus...
ABSTRACT The objective of this paper is to investigate long-term inter-annual, seasonal, and diur... more ABSTRACT The objective of this paper is to investigate long-term inter-annual, seasonal, and diurnal rainfall characteristics in the Southeastern United States. In order to capture precipitation features at high resolution, we use precipitation estimates from the Tropical Rainfall Measuring Mission (TRMM); the TRMM Precipitation Radar (TPR 2A25: 0.05° × 0.05°/daily) and the TRMM Multi-satellite Precipitation Analysis (TMPA 3B42: 0.25° × 0.25°/3-h) datasets to create a 13-year rainfall climatology. The higher resolution climatology (2A25) displays a greater ability to capture more localized landform precipitation features when compared with 3B42. On an annual basis, the Southeastern US is characterized by a succession of cold and warm precipitation regimes. The cold season is characterized by higher rain intensity West of 82°W (roughly Atlanta, GA) and the warm season is characterized by higher rain intensity over the coastal areas. The cold/warm rainfall regime duality is modulated by local topographic characteristics that prevail along a W–E direction. During the cold season, the diurnal cycle of precipitation is characterized by a quasi-constant repartition of rain events throughout the day and an absence of land/ocean contrast. On the contrary for summertime there is a strong land/ocean signature with a predominance of late morning/early afternoon (12:00–15:00LST) rainfall over ocean and afternoon/early evening (15:00–18:00LST) precipitation events over land that account for more than 25% of the daily events along the coasts. Differences are observed for the Florida peninsula, where the diurnal cycle displays an afternoon maximum of variable intensity due to sea breeze effects regardless of the season.
Bulletin of the American Meteorological Society, 2015
A new retrospective satellite-based precipitation dataset is constructed as a climate data record... more A new retrospective satellite-based precipitation dataset is constructed as a climate data record for hydrological and climate studies. Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record (PERSIANN-CDR) provides daily and 0.25° rainfall estimates for the latitude band 60°S–60°N for the period of 1 January 1983 to 31 December 2012 (delayed present). PERSIANN-CDR is aimed at addressing the need for a consistent, long-term, high-resolution, and global precipitation dataset for studying the changes and trends in daily precipitation, especially extreme precipitation events, due to climate change and natural variability. PERSIANN-CDR is generated from the PERSIANN algorithm using GridSat-B1 infrared data. It is adjusted using the Global Precipitation Climatology Project (GPCP) monthly product to maintain consistency of the two datasets at 2.5° monthly scale throughout the entire record. Three case studies for testing the efficacy ...
ABSTRACT The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have imp... more ABSTRACT The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented the NWS operational Multi-sensor Precipitation Estimation (MPE) algorithm with the historical NEXRAD data, the Digital Precipitation Array (DPA) products, in a reanalysis mode to develop a data set that is suited for long term climatological applications. The reanalysis is set up in a pilot domain over North and South Carolina for a 10 year period (1996-2007) and includes six WSR-88D sites. In this study we provide an evaluation of the multi-sensor precipitation reanalysis (MPR) over this region. In addition we provide comparisons with the operational Stage IV multi-sensor precipitation estimate. The evaluation of the MPR includes rain gauge (point) and radar-rainfall (pixel) comparisons at several temporal scales. A high density network from the Charlotte-Mecklenburg area (USGS) is used as it has a high temporal resolution (5-min) with a long period of record. Other rain gauge networks are from the North Carolina Mesonet and the U.S Climate Reference Network (USCRN). We present results of this evaluation via standard statistics, i.e. correlation coefficient, bias, and mean squared error. Another method of evaluation presented includes the mean squared error decomposition. In addition, we will investigate non-standard methods of evaluation such as Hovmoller diagrams, gridded correlation functions, and time series analysis.
A radar rainfall climatology has been developed based on approximately 10 years of NEXRAD level I... more A radar rainfall climatology has been developed based on approximately 10 years of NEXRAD level III data for several radars in the Carolina region of the southeast U.S. We are using this radar rainfall climatology to investigate the variability and trends of precipitation patterns based on the high resoution radar rainfall data. The data set is provided at hourly 4x4 km2 resolution and will be integrated to daily, monthly, seasonal, and annual temporal scales. Several issues have arisen during the development of the radar rainfall climatology related to inherent biases in the radar rainfall estimates, and several steps have been taken to reduce or eliminate these biases. Image processing techniques have been applied to try and elimate bright band and anomalous propagation. The radar range extent has been reduced to eliminate the effects of range on the rainfall estimates, and radar calibration bias adjustment has been applied to smooth radar to radar bias effects. These improved rai...
ABSTRACT [1] A study was performed to characterize over land precipitation associated with tropic... more ABSTRACT [1] A study was performed to characterize over land precipitation associated with tropical cyclones (TCs) for basins around the world based upon the International Best Track Archive for Climate Stewardship (IBTrACS). From 1998 to 2009, data from the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42, showed that TCs accounted for 5.5%, 7.5%, 6%, 9.5%, and 8.9% of the annual precipitation for impacted over land areas of the Americas, East Asia, South and West Asia, Oceania, and East Africa respectively, and that TC contribution decreased significantly within the first 150 km from the coast. Locally, TCs contributed on average to more than 25% and up to 61% of the annual precipitation budget over very different climatic areas with arid or tropical characteristics. East Asia represented the higher and most constant TC rain (118 mm yr−1±19%) normalized over the area impacted, while East Africa presented the highest variability (108 mm yr−1±60%), and the Americas displayed the lowest average TC rain (65 mm yr−1±24%) despite a higher TC activity. Furthermore, the maximum monthly TC contribution (8–11%) was found later in the TC season and depended on the peak of TC activity, TC rainfall, and the domain transition between dry and wet regimes if any. Finally, because of their importance in terms of rainfall amount, the contribution of TCs was provided for a selection of 50 urban areas experiencing cyclonic activity. Results showed that for particularly intense years, urban areas prone to cyclonic activity received more than half of their annual rainfall from TCs.
The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented ... more The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented the NWS operational Multi-sensor Precipitation Estimation (MPE) algorithm with the historical NEXRAD data, the Digital Precipitation Array (DPA) products, in a reanalysis mode to develop a data set that is suited for long term climatological applications. The reanalysis is set up in a pilot domain over North and South Carolina for a 10 year period (1996-2005) and includes six WSR-88D sites. One of the main improvements included in the reanalysis is to incorporate more in-situ measurements of rainfall which are important for the bias correction procedures. Higher quality and higher density rain gauge measurements will help improve the multisensor rainfall estimates. Further the reanalysis allows for detailed experiments for parameter tuning. All of these experiments will allow us to improve current estimates such that they are more suited for long term water resources and climate applicat...
ABSTRACT In this paper, we present a methodology for the selection of reach length in unsteady, o... more ABSTRACT In this paper, we present a methodology for the selection of reach length in unsteady, one-dimensional models of open channel flow. Using computational experiments, we determined an appropriate reach length for 425 combinations of channel and flow parameters. For each combination of parameters, we refined the finite difference grid until numerical error was reduced to 1.0% of a high resolution solution. We generated a set of dimensionless parameters and used regression analysis to relate channel and flood properties to an appropriate computational reach length.
The objective of this paper is to characterize the precipitation amounts originating from tropica... more The objective of this paper is to characterize the precipitation amounts originating from tropical cyclones (TCs) in the southeastern United States during the tropical storm season from June to November. Using 12 years of precipitation data from the Tropical Rainfall Measurement Mission (TRMM), the authors estimate the TC contribution on the seasonal, interannual, and monthly precipitation budget using TC information derived from the International Best Track Archive for Climate Stewardship (IBTrACS). Results derived from the TRMM Multisatellite Precipitation Analysis (TMPA) 3B42 showed that TCs accounted for about 7% of the seasonal precipitation total from 1998 to 2009. Rainfall attributable to TCs was found to contribute as much as 8%–12% for inland areas located between 150 and 300 km from the coast and up to 15%–20% for coastal areas from Louisiana to the Florida Panhandle, southern Florida, and coastal Carolinas. The interannual contribution varied from 1.3% to 13.8% for the pe...
ABSTRACT This paper presents a comprehensive intercomparison analysis of different radar-based mu... more ABSTRACT This paper presents a comprehensive intercomparison analysis of different radar-based multisensor precipitation products generated operationally by the National Weather Service (NWS) Multisensor Precipitation Estimator (MPE) algorithm from the Weather Surveillance Radar-1988 Doppler version and concurrent rain gauge data. The analysis provides close insight into different effects of the increasing degree of complexitzy in the MPE algorithms. First, a gauge-only product produced by the MPE algorithm was assessed. Then six MPE products were analyzed: a radar-only product, a mean-field bias-adjusted product, a local bias-adjusted product, two products that are based on merging the bias-adjusted products with gauge observations, and a final product that includes human intervention by NWS forecasters. Data from a dense, carefully maintained experimental rain gauge cluster are used as an independent surface reference. A number of summary and conditional statistics are applied to the product intercomparisons. The results reported in this paper show that the most effective improvement of the rainfall products comes from applying the mean-field bias adjustment to the radar-only product. The analysis demonstrates that, for the current study site, some best-intended schemes for the optimal merging of radar and rain gauge data processing did not necessarily lead to clear improvements and, in some respects, caused accuracy degradation in the final products. This behavior by the MPE merging schemes is possibly attributed to the rather poor density of operational rain gauges that need to be available in real time for the implementation of such schemes. Future research is required to examine whether this behavior persists in other regions that may have better coverage and availability of operational rain gauges. DOI: 10.1061/(ASCE)HE.1943-5584.0000638. (C) 2013 American Society of Civil Engineers.
Passive microwave measurements have been available on satellites dating back to the 1970s on rese... more Passive microwave measurements have been available on satellites dating back to the 1970s on research satellites flown by the National Aeronautics and Space Administration (NASA). Since then, several other sensors have been flown to retrieve hydrological products for both operational weather applications (e.g., the Special Sensor Microwave/Imager–SSM/I; the Advanced Microwave Sounding Unit–AMSU) and climate applications (e.g., the Advanced Microwave Scanning Radiometer–AMSR; the Tropical Rainfall Measurement Mission Microwave Imager–TMI; the Global Precipitation Mission Microwave Imager–GMI). Here the focus is on measurements from the AMSU-A, AMSU-B and Microwave Humidity Sounder (MHS). These sensors have been in operation since 1998 with the launch of NOAA-15, and are also on board NOAA-16, -17, -18, -19 and the MetOp-A and -B satellites. A data set called the “Hydrological Bundle” is a Climate Data Record (CDR) that utilizes brightness tem...
Precipitation estimation by weather radars in Alaska is challenging. In this study, we investigat... more Precipitation estimation by weather radars in Alaska is challenging. In this study, we investigate National Weather Service (NWS) precipitation products that are produced from the seven NEXRAD radar sites in Alaska. The NWS precipitation processing subsystem generates stages of data at each NEXRAD site which are then input to the weather forecast office to generate a regionwide precipitation product. Data from the NEXRAD sites and the operational rain gauges in the weather forecast region are used to produce this regionwide product that is then sent to the National Centers for Environmental Prediction (NCEP) to be included in the NCEP Stage IV distribution. The NCEP Stage IV product for Alaska has been available since 2017. We use the United States Climate Reference Network (USCRN) data from Alaska to compare to the NCEP Stage IV data. Given that the USCRN can be used in the production of the NCEP Stage IV data for Alaska, we also used the NEXRAD Digital Precipitation Array (DPA) th...
We use a suite of quantitative precipitation estimates (QPEs) derived from satellite, radar, and ... more We use a suite of quantitative precipitation estimates (QPEs) derived from satellite, radar, and surface observations to derive precipitation characteristics over the contiguous United States (CONUS) for the period 2002–2012. This comparison effort includes satellite multi-sensor data sets (bias-adjusted TMPA 3B42, near-real-time 3B42RT), radar estimates (NCEP Stage IV), and rain gauge observations. Remotely sensed precipitation data sets are compared with surface observations from the Global Historical Climatology Network-Daily (GHCN-D) and from the PRISM (Parameter-elevation Regressions on Independent Slopes Model). The comparisons are performed at the annual, seasonal, and daily scales over the River Forecast Centers (RFCs) for CONUS. Annual average rain rates present a satisfying agreement with GHCN-D for all products over CONUS (±6%). However, differences at the RFC are more important in particular for near-real-time 3B42RT precipitation estimates (−33 to +49%). At annual and s...
Proquest Dissertations and Theses Thesis the University of Iowa 2003 Publication Number Aai3097561 Isbn 9780496451746 Source Dissertation Abstracts International Volume 64 07 Section B Page 3157 152 P, 2003
The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation esti... more The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation estimates (QPEs) are used in many studies for intercomparisons including those for satellite QPEs. An overview of the National Weather Service precipitation processing system is provided here so as to set the stage IV product in context and to provide users with some knowledge as to how it is developed. Then, an assessment of the stage IV product over the period 2002–12 is provided. The assessment shows that the stage IV product can be useful for conditional comparisons of moderate-to-heavy rainfall for select seasons and locations. When evaluating the product at the daily scale, there are many discontinuities due to the operational processing at the radar site as well as discontinuities due to the merging of data from different River Forecast Centers (RFCs) that use much different processing algorithms for generating their precipitation estimates. An assessment of the daily precipitation es...
The precipitation climatology of the Southeastern United States and the Carolinas region in parti... more The precipitation climatology of the Southeastern United States and the Carolinas region in particular spans a very broad spectrum of precipitation regimes. A warm season that is characterized by isolated thunderstorms, squall line mesoscale convective systems, and tropical cyclones, and a winter season characterized by widespread frontal rain, ice, and snowfall. Each of these types of precipitation system impacts regional hydrology in very different ways, and are associated with a large variety of natural hazards. In this work, we propose to develop a comprehensive climatology of precipitation using a multi-sensor approach (ground based: Q2, rain gauges; and remotely sensed: TRMM PR) with the goal to derive hydrological characteristics of precipitation. The goal of this study is two-fold. In the first aspect of this work we will derive diurnal, seasonal, and yearly trends as it concern the temporal frequency and spatial distribution of precipitation patterns with a particular focus...
ABSTRACT The objective of this paper is to investigate long-term inter-annual, seasonal, and diur... more ABSTRACT The objective of this paper is to investigate long-term inter-annual, seasonal, and diurnal rainfall characteristics in the Southeastern United States. In order to capture precipitation features at high resolution, we use precipitation estimates from the Tropical Rainfall Measuring Mission (TRMM); the TRMM Precipitation Radar (TPR 2A25: 0.05° × 0.05°/daily) and the TRMM Multi-satellite Precipitation Analysis (TMPA 3B42: 0.25° × 0.25°/3-h) datasets to create a 13-year rainfall climatology. The higher resolution climatology (2A25) displays a greater ability to capture more localized landform precipitation features when compared with 3B42. On an annual basis, the Southeastern US is characterized by a succession of cold and warm precipitation regimes. The cold season is characterized by higher rain intensity West of 82°W (roughly Atlanta, GA) and the warm season is characterized by higher rain intensity over the coastal areas. The cold/warm rainfall regime duality is modulated by local topographic characteristics that prevail along a W–E direction. During the cold season, the diurnal cycle of precipitation is characterized by a quasi-constant repartition of rain events throughout the day and an absence of land/ocean contrast. On the contrary for summertime there is a strong land/ocean signature with a predominance of late morning/early afternoon (12:00–15:00LST) rainfall over ocean and afternoon/early evening (15:00–18:00LST) precipitation events over land that account for more than 25% of the daily events along the coasts. Differences are observed for the Florida peninsula, where the diurnal cycle displays an afternoon maximum of variable intensity due to sea breeze effects regardless of the season.
Bulletin of the American Meteorological Society, 2015
A new retrospective satellite-based precipitation dataset is constructed as a climate data record... more A new retrospective satellite-based precipitation dataset is constructed as a climate data record for hydrological and climate studies. Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record (PERSIANN-CDR) provides daily and 0.25° rainfall estimates for the latitude band 60°S–60°N for the period of 1 January 1983 to 31 December 2012 (delayed present). PERSIANN-CDR is aimed at addressing the need for a consistent, long-term, high-resolution, and global precipitation dataset for studying the changes and trends in daily precipitation, especially extreme precipitation events, due to climate change and natural variability. PERSIANN-CDR is generated from the PERSIANN algorithm using GridSat-B1 infrared data. It is adjusted using the Global Precipitation Climatology Project (GPCP) monthly product to maintain consistency of the two datasets at 2.5° monthly scale throughout the entire record. Three case studies for testing the efficacy ...
ABSTRACT The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have imp... more ABSTRACT The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented the NWS operational Multi-sensor Precipitation Estimation (MPE) algorithm with the historical NEXRAD data, the Digital Precipitation Array (DPA) products, in a reanalysis mode to develop a data set that is suited for long term climatological applications. The reanalysis is set up in a pilot domain over North and South Carolina for a 10 year period (1996-2007) and includes six WSR-88D sites. In this study we provide an evaluation of the multi-sensor precipitation reanalysis (MPR) over this region. In addition we provide comparisons with the operational Stage IV multi-sensor precipitation estimate. The evaluation of the MPR includes rain gauge (point) and radar-rainfall (pixel) comparisons at several temporal scales. A high density network from the Charlotte-Mecklenburg area (USGS) is used as it has a high temporal resolution (5-min) with a long period of record. Other rain gauge networks are from the North Carolina Mesonet and the U.S Climate Reference Network (USCRN). We present results of this evaluation via standard statistics, i.e. correlation coefficient, bias, and mean squared error. Another method of evaluation presented includes the mean squared error decomposition. In addition, we will investigate non-standard methods of evaluation such as Hovmoller diagrams, gridded correlation functions, and time series analysis.
A radar rainfall climatology has been developed based on approximately 10 years of NEXRAD level I... more A radar rainfall climatology has been developed based on approximately 10 years of NEXRAD level III data for several radars in the Carolina region of the southeast U.S. We are using this radar rainfall climatology to investigate the variability and trends of precipitation patterns based on the high resoution radar rainfall data. The data set is provided at hourly 4x4 km2 resolution and will be integrated to daily, monthly, seasonal, and annual temporal scales. Several issues have arisen during the development of the radar rainfall climatology related to inherent biases in the radar rainfall estimates, and several steps have been taken to reduce or eliminate these biases. Image processing techniques have been applied to try and elimate bright band and anomalous propagation. The radar range extent has been reduced to eliminate the effects of range on the rainfall estimates, and radar calibration bias adjustment has been applied to smooth radar to radar bias effects. These improved rai...
ABSTRACT [1] A study was performed to characterize over land precipitation associated with tropic... more ABSTRACT [1] A study was performed to characterize over land precipitation associated with tropical cyclones (TCs) for basins around the world based upon the International Best Track Archive for Climate Stewardship (IBTrACS). From 1998 to 2009, data from the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42, showed that TCs accounted for 5.5%, 7.5%, 6%, 9.5%, and 8.9% of the annual precipitation for impacted over land areas of the Americas, East Asia, South and West Asia, Oceania, and East Africa respectively, and that TC contribution decreased significantly within the first 150 km from the coast. Locally, TCs contributed on average to more than 25% and up to 61% of the annual precipitation budget over very different climatic areas with arid or tropical characteristics. East Asia represented the higher and most constant TC rain (118 mm yr−1±19%) normalized over the area impacted, while East Africa presented the highest variability (108 mm yr−1±60%), and the Americas displayed the lowest average TC rain (65 mm yr−1±24%) despite a higher TC activity. Furthermore, the maximum monthly TC contribution (8–11%) was found later in the TC season and depended on the peak of TC activity, TC rainfall, and the domain transition between dry and wet regimes if any. Finally, because of their importance in terms of rainfall amount, the contribution of TCs was provided for a selection of 50 urban areas experiencing cyclonic activity. Results showed that for particularly intense years, urban areas prone to cyclonic activity received more than half of their annual rainfall from TCs.
The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented ... more The National Climatic Data Center (NCDC) and the National Weather Service (NWS) have implemented the NWS operational Multi-sensor Precipitation Estimation (MPE) algorithm with the historical NEXRAD data, the Digital Precipitation Array (DPA) products, in a reanalysis mode to develop a data set that is suited for long term climatological applications. The reanalysis is set up in a pilot domain over North and South Carolina for a 10 year period (1996-2005) and includes six WSR-88D sites. One of the main improvements included in the reanalysis is to incorporate more in-situ measurements of rainfall which are important for the bias correction procedures. Higher quality and higher density rain gauge measurements will help improve the multisensor rainfall estimates. Further the reanalysis allows for detailed experiments for parameter tuning. All of these experiments will allow us to improve current estimates such that they are more suited for long term water resources and climate applicat...
ABSTRACT In this paper, we present a methodology for the selection of reach length in unsteady, o... more ABSTRACT In this paper, we present a methodology for the selection of reach length in unsteady, one-dimensional models of open channel flow. Using computational experiments, we determined an appropriate reach length for 425 combinations of channel and flow parameters. For each combination of parameters, we refined the finite difference grid until numerical error was reduced to 1.0% of a high resolution solution. We generated a set of dimensionless parameters and used regression analysis to relate channel and flood properties to an appropriate computational reach length.
The objective of this paper is to characterize the precipitation amounts originating from tropica... more The objective of this paper is to characterize the precipitation amounts originating from tropical cyclones (TCs) in the southeastern United States during the tropical storm season from June to November. Using 12 years of precipitation data from the Tropical Rainfall Measurement Mission (TRMM), the authors estimate the TC contribution on the seasonal, interannual, and monthly precipitation budget using TC information derived from the International Best Track Archive for Climate Stewardship (IBTrACS). Results derived from the TRMM Multisatellite Precipitation Analysis (TMPA) 3B42 showed that TCs accounted for about 7% of the seasonal precipitation total from 1998 to 2009. Rainfall attributable to TCs was found to contribute as much as 8%–12% for inland areas located between 150 and 300 km from the coast and up to 15%–20% for coastal areas from Louisiana to the Florida Panhandle, southern Florida, and coastal Carolinas. The interannual contribution varied from 1.3% to 13.8% for the pe...
ABSTRACT This paper presents a comprehensive intercomparison analysis of different radar-based mu... more ABSTRACT This paper presents a comprehensive intercomparison analysis of different radar-based multisensor precipitation products generated operationally by the National Weather Service (NWS) Multisensor Precipitation Estimator (MPE) algorithm from the Weather Surveillance Radar-1988 Doppler version and concurrent rain gauge data. The analysis provides close insight into different effects of the increasing degree of complexitzy in the MPE algorithms. First, a gauge-only product produced by the MPE algorithm was assessed. Then six MPE products were analyzed: a radar-only product, a mean-field bias-adjusted product, a local bias-adjusted product, two products that are based on merging the bias-adjusted products with gauge observations, and a final product that includes human intervention by NWS forecasters. Data from a dense, carefully maintained experimental rain gauge cluster are used as an independent surface reference. A number of summary and conditional statistics are applied to the product intercomparisons. The results reported in this paper show that the most effective improvement of the rainfall products comes from applying the mean-field bias adjustment to the radar-only product. The analysis demonstrates that, for the current study site, some best-intended schemes for the optimal merging of radar and rain gauge data processing did not necessarily lead to clear improvements and, in some respects, caused accuracy degradation in the final products. This behavior by the MPE merging schemes is possibly attributed to the rather poor density of operational rain gauges that need to be available in real time for the implementation of such schemes. Future research is required to examine whether this behavior persists in other regions that may have better coverage and availability of operational rain gauges. DOI: 10.1061/(ASCE)HE.1943-5584.0000638. (C) 2013 American Society of Civil Engineers.
Passive microwave measurements have been available on satellites dating back to the 1970s on rese... more Passive microwave measurements have been available on satellites dating back to the 1970s on research satellites flown by the National Aeronautics and Space Administration (NASA). Since then, several other sensors have been flown to retrieve hydrological products for both operational weather applications (e.g., the Special Sensor Microwave/Imager–SSM/I; the Advanced Microwave Sounding Unit–AMSU) and climate applications (e.g., the Advanced Microwave Scanning Radiometer–AMSR; the Tropical Rainfall Measurement Mission Microwave Imager–TMI; the Global Precipitation Mission Microwave Imager–GMI). Here the focus is on measurements from the AMSU-A, AMSU-B and Microwave Humidity Sounder (MHS). These sensors have been in operation since 1998 with the launch of NOAA-15, and are also on board NOAA-16, -17, -18, -19 and the MetOp-A and -B satellites. A data set called the “Hydrological Bundle” is a Climate Data Record (CDR) that utilizes brightness tem...
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