scholarly journals Spatiotemporal Variability of Hourly Precipitation over the Eastern Contiguous United States from Stage IV Multisensor Analyses

2008 ◽  
Vol 9 (1) ◽  
pp. 3-21 ◽  
Author(s):  
Ana L. Kursinski ◽  
Steven L. Mullen
Keyword(s):  
United States ◽  
Numerical Models ◽  
Geometric Model ◽  
Stage Iv ◽  
Spatiotemporal Variability ◽  
Eastern United States ◽  
Hourly Precipitation ◽  
Prediction Systems ◽  
Decorrelation Estimates

Abstract The statistical character of precipitation events from hourly stage IV analyses is documented for the eastern United States during the cool [December–February (DJF)] and the warm [June–August (JJA)] seasons for the four years of 2002–05. Isotropic e-folding distances and in situ e-folding times are computed for mesh sizes that vary from 4 km (the minimal stage IV pixel size) to 32 km for two thresholds: light (1 mm h−1) and heavy (5 mm h−1) precipitation rates. Marked seasonal variability characterizes the e-folding times. They typically run between 2 and 3 h during winter and 1 and 2 h during summer for light events, and they run an hour shorter for heavy rainfall during both seasons. Spatial decorrelation estimates also reveal considerable seasonal and geographical variability; e-folding distances typically lie between 60 and 180 km during the winter and between 30 and 60 km during the summer for light episodes, and they are approximately a factor of 2 to 3 shorter for heavy events. Anisotropic statistics are estimated by a simple geometric model. Hourly precipitation patterns show a preference for a southwest–northeast orientation during both seasons with greater elongation during the winter. Mean propagation velocities of precipitating systems are faster and are more closely aligned with the dilatation axis during the winter. These statistics should provide useful guidance for diagnosing and improving the spatiotemporal variance characteristics of precipitation for downscaling algorithms and numerical models of hydrometeorological prediction systems.

scholarly journals Can the GPM IMERG Final Product Accurately Represent MCSs’ Precipitation Characteristics over the Central and Eastern United States?

2020 ◽  
Vol 21 (1) ◽  
pp. 39-57 ◽  
Author(s):  
Wenjun Cui ◽  
Xiquan Dong ◽  
Baike Xi ◽  
Zhe Feng ◽  
Jiwen Fan
Keyword(s):  
United States ◽  
False Alarm ◽  
Stage Iv ◽  
Cloud Base ◽  
Eastern United States ◽  
Convective Systems ◽  
Precipitation Measurement ◽  
Precipitation Characteristics ◽  
Mesoscale Convective ◽  
Global Precipitation

AbstractMesoscale convective systems (MCSs) play an important role in water and energy cycles as they produce heavy rainfall and modify the radiative profile in the tropics and midlatitudes. An accurate representation of MCSs’ rainfall is therefore crucial in understanding their impact on the climate system. The V06B Integrated Multisatellite Retrievals from Global Precipitation Measurement (IMERG) half-hourly precipitation final product is a useful tool to study the precipitation characteristics of MCSs because of its global coverage and fine spatiotemporal resolutions. However, errors and uncertainties in IMERG should be quantified before applying it to hydrology and climate applications. This study evaluates IMERG performance on capturing and detecting MCSs’ precipitation in the central and eastern United States during a 3-yr study period against the radar-based Stage IV product. The tracked MCSs are divided into four seasons and are analyzed separately for both datasets. IMERG shows a wet bias in total precipitation but a dry bias in hourly mean precipitation during all seasons due to the false classification of nonprecipitating pixels as precipitating. These false alarm events are possibly caused by evaporation under the cloud base or the misrepresentation of MCS cold anvil regions as precipitating clouds by the algorithm. IMERG agrees reasonably well with Stage IV in terms of the seasonal spatial distribution and diurnal cycle of MCSs precipitation. A relative humidity (RH)-based correction has been applied to the IMERG precipitation product, which helps reduce the number of false alarm pixels and improves the overall performance of IMERG with respect to Stage IV.

scholarly journals A 10-Year Survey of Extreme Rainfall Events in the Central and Eastern United States Using Gridded Multisensor Precipitation Analyses

2014 ◽  
Vol 142 (9) ◽  
pp. 3147-3162 ◽  
Author(s):  
Stephanie N. Stevenson ◽  
Russ S. Schumacher
Keyword(s):  
United States ◽  
Tropical Cyclones ◽  
Stage Iv ◽  
Extreme Rainfall ◽  
Eastern United States ◽  
Weather System ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Convective Systems ◽  
Maximum Minimum

Extreme rainfall events in the central and eastern United States during 2002–11 were identified using NCEP stage-IV precipitation analyses. Precipitation amounts were compared against established 50- and 100-yr recurrence interval thresholds for 1-, 6-, and 24-h durations. The authors identified points where analyzed precipitation exceeded the threshold, and combined points associated with the same weather system into events. At shorter durations, points exceeding the thresholds were most common in the Southeast, whereas points were more uniformly distributed for the 24-h duration. Most 24-h events have more points than the other durations, reflecting the importance of organized precipitation systems on longer temporal scales. Though monthly peaks varied by region, the maximum (minimum) usually occurred during the summer (winter); however, the 24-h point maximum occurred in September owing to tropical cyclones. The maximum (minimum) in hourly extreme rainfall points occurred at 2300 (1100) LST, though there were regional differences in the timing of the diurnal maxima and minima. Over half of 100-yr, 24-h events were a result of mesoscale convective systems (MCS), with synoptic and tropical systems responsible for nearly one-third and one-tenth, respectively. Of the 10 events with the most points exceeding this threshold, 5 were associated with tropical cyclones, 3 were synoptic events, and 2 were MCSs. Among the MCS events, 7 of the top 10 were training line/adjoining stratiform (TL/AS). While the 49 TL/AS events investigated further had similar moisture availability, the more widespread events had stronger low-level winds, stronger warm air advection, and stronger and more expansive frontogenesis in the inflow.

scholarly journals Spatiotemporal Variability of Tropical Cyclone Precipitation Using a High-Resolution, Gridded (0.25° × 0.25°) Dataset for the Eastern United States, 1948–2015

2020 ◽  
Vol 33 (5) ◽  
pp. 1803-1819 ◽  
Author(s):  
Joshua C. Bregy ◽  
Justin T. Maxwell ◽  
Scott M. Robeson ◽  
Jason T. Ortegren ◽  
Peter T. Soulé ◽  
...  
Keyword(s):  
United States ◽  
Tropical Cyclone ◽  
Large Scale ◽  
Southern Oscillation ◽  
Spatiotemporal Variability ◽  
Eastern United States ◽  
Percentage Contribution ◽  
Rain Gauges ◽  
The North ◽  
Climate Interactions

AbstractTropical cyclones (TCs) are an important source of precipitation for much of the eastern United States. However, our understanding of the spatiotemporal variability of tropical cyclone precipitation (TCP) and the connections to large-scale atmospheric circulation is limited by irregularly distributed rain gauges and short records of satellite measurements. To address this, we developed a new gridded (0.25° × 0.25°) publicly available dataset of TCP (1948–2015; Tropical Cyclone Precipitation Dataset, or TCPDat) using TC tracks to identify TCP within an existing gridded precipitation dataset. TCPDat was used to characterize total June–November TCP and percentage contribution to total June–November precipitation. TCP totals and contributions had maxima on the Louisiana, North Carolina, and Texas coasts, substantially decreasing farther inland at rates of approximately 6.2–6.7 mm km−1. Few statistically significant trends were discovered in either TCP totals or percentage contribution. TCP is positively related to an index of the position and strength of the western flank of the North Atlantic subtropical high (NASH), with the strongest correlations concentrated in the southeastern United States. Weaker inverse correlations between TCP and El Niño–Southern Oscillation are seen throughout the study site. Ultimately, spatial variations of TCP are more closely linked to variations in the NASH flank position or strength than to the ENSO index. The TCP dataset developed in this study is an important step in understanding hurricane–climate interactions and the impacts of TCs on communities, water resources, and ecosystems in the eastern United States.

scholarly journals An Examination of Precipitation in Observations and Model Forecasts during NAME with Emphasis on the Diurnal Cycle

2007 ◽  
Vol 20 (9) ◽  
pp. 1680-1692 ◽  
Author(s):  
John E. Janowiak ◽  
Valery J. Dagostaro ◽  
Vernon E. Kousky ◽  
Robert J. Joyce
Keyword(s):  
United States ◽  
Diurnal Cycle ◽  
Prediction Models ◽  
Numerical Models ◽  
The United States ◽  
Rain Gauge ◽  
North American Monsoon ◽  
Eastern United States ◽  
Direct Evaluation ◽  
The North

Abstract Summertime rainfall over the United States and Mexico is examined and is compared with forecasts from operational numerical prediction models. In particular, the distribution of rainfall amounts is examined and the diurnal cycle of rainfall is investigated and compared with the model forecasts. This study focuses on a 35-day period (12 July–15 August 2004) that occurred amid the North American Monsoon Experiment (NAME) field campaign. Three-hour precipitation forecasts from the numerical models were validated against satellite-derived estimates of rainfall that were adjusted by daily rain gauge data to remove bias from the remotely sensed estimates. The model forecasts that are evaluated are for the 36–60-h period after the model initial run time so that the effects of updated observational data are reduced substantially and a more direct evaluation of the model precipitation parameterization can be accomplished. The main findings of this study show that the effective spatial resolution of the model-generated precipitation is considerably more coarse than the native model resolution. On a national scale, the models overforecast the frequency of rainfall events in the 1–75 mm day−1 range and underforecast heavy events (>85 mm day−1). The models also have a diurnal cycle that peaks 3–6 h earlier than is observed over portions of the eastern United States and the NAME tier-1 region. Time series and harmonic analysis are used to identify where the models perform well and poorly in characterizing the amplitude and phase of the diurnal cycle of precipitation.

Direct 4D-Var Assimilation of NCEP Stage IV Radar and Gauge Precipitation Data at ECMWF

2011 ◽  
Vol 139 (7) ◽  
pp. 2098-2116 ◽  
Author(s):  
Philippe Lopez
Keyword(s):  
United States ◽  
Natural Extension ◽  
Stage Iv ◽  
Eastern United States ◽  
Rain Gauges ◽  
Model Background ◽  
Hourly Data ◽  
Forecasting System ◽  
Assimilation Process ◽  
The Moment

Abstract Direct four-dimensional variational data assimilation (4D-Var) of NCEP stage IV radar and gauge precipitation observations over the eastern United States has been developed and tested in ECMWF’s global Integrated Forecasting System. This is the natural extension of earlier work using a two-step 1D+4D-Var approach. Major aspects of the implementation are described and discussed in this paper. In particular, it is found that assimilating 6-h precipitation accumulations instead of the original hourly data substantially improves the behavior of 4D-Var, especially as regards the validity of the tangent-linear assumption. The comparison of background and analysis precipitation departures demonstrates that most of the information contained in the new precipitation observations is properly assimilated. Experiments run over the periods April–May and September–October 2009 also show that local precipitation forecasts become significantly better for ranges up to 12 h, which indicates that a genuine precipitation analysis can now be obtained over the eastern United States. Geopotential, temperature, moisture, and wind forecast scores are generally neutral or slightly positive for all regions of the globe and at all ranges, which is consistent with previous 1D+4D-Var results. The most crucial issue that remains unsolved is the treatment of nonprecipitating model background occurrences because of the corresponding absence of sensitivity in the linearized moist physics. For the moment, only points where both model background and observations are rainy are assimilated. Operational implementation using U.S. data is planned in 2011 and one can hope that new networks of radars (and maybe rain gauges) can be added in the 4D-Var assimilation process in the future.

Comparative statistical study of hourly precipitation determined by radar-based Stage IV and ground-based methods in the North Central United States

2013 ◽  
Vol 64 (3) ◽  
pp. 291-308 ◽  
Author(s):  
Pietro A. Catizone ◽  
Steven E. Zell ◽  
Christopher R. Arrington ◽  
Michael B. Newman ◽  
Steven F. Weber ◽  
...  
Keyword(s):  
United States ◽  
Statistical Study ◽  
Stage Iv ◽  
North Central ◽  
Hourly Precipitation ◽  
The North ◽  
Central United States

Haloform formation in coastal wetlands along a salinity gradient at South Carolina, United States

2016 ◽  
Vol 13 (4) ◽  
pp. 745 ◽  
Author(s):  
Jun-Jian Wang ◽  
Yi Jiao ◽  
Robert C. Rhew ◽  
Alex T. Chow
Keyword(s):  
United States ◽  
South Carolina ◽  
Sea Level ◽  
Water Samples ◽  
Coastal Wetlands ◽  
Salinity Gradient ◽  
Freshwater Wetland ◽  
Eastern United States ◽  
Soil And Water

Environmental contextNatural haloform emissions contribute to stratospheric ozone depletion but there are major unknown or underestimated sources of these gases. This study demonstrates that soil and water at tidal wetlands are important haloform sources, and emissions peak at the forest–marsh transition zone. The low-lying forested wetlands of the south-eastern United States that are facing sea-level rise and seawater intrusion may become hotspots for haloform emission. AbstractSoil haloform emissions are sources of reactive halogens that catalytically deplete ozone in the stratosphere but there are still unknown or underestimated haloform sources. The >200000ha of low-lying tidal freshwater swamps (forests and marshes) in the south-eastern United States could be haloform (CHX3, X=Cl or Br) sources because sea-level rise and saltwater intrusion bring halides inland where they mix with terrestrial humic substances. To evaluate the spatial variation along the common forest–marsh salinity gradient (freshwater wetland, oligohaline wetland and mesohaline saltmarsh), we measured chloroform emissions from in situ chambers and from laboratory incubations of soil and water samples collected from Winyah Bay, South Carolina. The in situ and soil-core haloform emissions were both highest in the oligohaline wetland, whereas the aqueous production was highest in mesohaline saltmarsh. The predominant source shifted from sediment emission to water emission from freshwater wetland to mesohaline saltmarsh. Spreading out soil samples increased soil haloform emission, suggesting that soil pores can trap high amounts of CHCl3. Soil sterilisation did not suppress CHCl3 emission, indicating the important contribution of abiotic soil CHCl3 formation. Surface wetland water samples from eight locations along a salinity gradient with different management practices (natural v. managed) were subjected to radical-based halogenation by Fenton-like reagents. Halide availability, organic matter source, temperature and light irradiation were all found to affect the radical-based abiotic haloform formation from surface water. This study clearly indicates that soil and water from the studied coastal wetlands are both haloform sources, which however appear to have different formation mechanisms.

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