scholarly journals Thailand Daily Rainfall and Comparison with TRMM Products

2008 ◽  
Vol 9 (2) ◽  
pp. 256-266 ◽  
Author(s):  
Roongroj Chokngamwong ◽  
Long S. Chiu
Keyword(s):  
Daily Rainfall ◽  
Tropical Rainfall Measuring Mission ◽  
Heavy Rain ◽  
Absolute Difference ◽  
Rain Event ◽  
Critical Success ◽  
Global Precipitation Climatology Centre ◽  
Temporal And Spatial ◽  
Rain Events ◽  
Rain Rates

Abstract Daily rainfall data collected from more than 100 gauges over Thailand for the period 1993–2002 are used to study the climatology and spatial and temporal characteristics of Thailand rainfall variations. Comparison of the Thailand gauge (TG) data binned at 1° × 1° with the Global Precipitation Climatology Centre (GPCC) monitoring product shows a small bias (1.11%), and the differences can be reconciled in terms of the increased number of stations in the TG dataset. Comparison of daily TG with Tropical Rainfall Measuring Mission (TRMM) version 6 (V6) 3B42 rain estimates shows improvements over version 5 (V5) in terms of bias and mean absolute difference (MAD). The V5 is computed from the adjusted Geostationary Operational Environmental Satellite (GOES) precipitation index (AGPI) and V6 is computed using the TRMM Multisatellite Precipitation Analysis (TMPA) algorithm. The V6 histogram is much closer to that of TG than V5 in terms of rain fraction and conditional rain rates. Scatterplots show that both versions of the satellite products are deficient in capturing heavy rain events. In terms of detecting rain events, a critical success index (CSI) shows no difference between V6 and V5 3B42. The CSI for V6 is higher for the rainy season than the dry season. These results are generally insensitive to rain-rate threshold and averaging periods. The temporal and spatial autocorrelation of daily rain rates for TG, V6, and V5 3B42 are computed. Autocorrelation function analyses show improved temporal and spatial autocorrelations for V6 compared to TG over V5 with e-folding times of 1, 1, and 2 days, and isotropic spatial decorrelation distances of 1.14°, 1.87°, and 3.61° for TG, V6, and V5, respectively. Rain event statistics show that the V6 3B42 overestimates the rain event durations and underestimates the rain event separations and the event conditional rain rates when compared to TG. This study points to the need to further improve the 3B42 algorithm to lower the false detection rate and improve the estimation of heavy rainfall events.

scholarly journals Comparisons of Instantaneous TRMM Ground Validation and Satellite Rain-Rate Estimates at Different Spatial Scales

2008 ◽  
Vol 47 (8) ◽  
pp. 2215-2237 ◽  
Author(s):  
David B. Wolff ◽  
Brad L. Fisher
Keyword(s):  
Rain Rate ◽  
Spatial Scales ◽  
Tropical Rainfall Measuring Mission ◽  
Heavy Rain ◽  
Global Ocean ◽  
Ground Validation ◽  
Microwave Imager ◽  
Rain Events ◽  
Trmm Microwave Imager ◽  
Rain Rates

Abstract This study provides a comprehensive intercomparison of instantaneous rain rates observed by the two rain sensors aboard the Tropical Rainfall Measuring Mission (TRMM) satellite with ground data from two regional sites established for long-term ground validation: Kwajalein Atoll and Melbourne, Florida. The satellite rain algorithms utilize remote observations of precipitation collected by the TRMM Microwave Imager (TMI) and the Precipitation Radar (PR) aboard the TRMM satellite. Three standard level II rain products are generated from operational applications of the TMI, PR, and combined (COM) rain algorithms using rain information collected from the TMI and the PR along the orbital track of the TRMM satellite. In the first part of the study, 0.5° × 0.5° instantaneous rain rates obtained from the TRMM 3G68 product were analyzed and compared to instantaneous Ground Validation (GV) program rain rates gridded at a scale of 0.5° × 0.5°. In the second part of the study, TMI, PR, COM, and GV rain rates were spatiotemporally matched and averaged at the scale of the TMI footprint (∼150 km2). This study covered a 6-yr period (1999–2004) and consisted of over 50 000 footprints for each GV site. In the first analysis, the results showed that all of the respective rain-rate estimates agree well, with some exceptions. The more salient differences were associated with heavy rain events in which one or more of the algorithms failed to properly retrieve these extreme events. Also, it appears that there is a preferred mode of precipitation for TMI rain rates at or near 2 mm h−1 over the ocean. This mode was noted over ocean areas of Kwajalein and Melbourne and has been observed in TRMM tropical–global ocean areas as well.

scholarly journals Spatial structures and directionalities in Monsoonal precipitation over South Asia

2010 ◽  
Vol 17 (5) ◽  
pp. 371-381 ◽  
Author(s):  
N. Malik ◽  
N. Marwan ◽  
J. Kurths
Keyword(s):  
Indian Subcontinent ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Rain ◽  
Data Sets ◽  
Spatial Structures ◽  
Break Phase ◽  
Rainfall Events ◽  
Monsoonal Precipitation ◽  
Rain Events

Abstract. Precipitation during the monsoon season over the Indian subcontinent occurs in form of enormously complex spatiotemporal patterns due to the underlying dynamics of atmospheric circulation and varying topography. Employing methods from nonlinear time series analysis, we study spatial structures of the rainfall field during the summer monsoon and identify principle regions where the dynamics of monsoonal rainfall is more coherent or homogenous. Moreover, we estimate the time delay patterns of rain events. Here we present an analysis of two separate high resolution gridded data sets of daily rainfall covering the Indian subcontinent. Using the method of event synchronization (ES), we estimate regions where heavy rain events during monsoon happen in some lag synchronised form. Further using the delay behaviour of rainfall events, we estimate the directionalities related to the progress of such type of rainfall events. The Active (break) phase of a monsoon is characterised by an increase(decrease) of rainfall over certain regions of the Indian subcontinent. We show that our method is able to identify regions of such coherent rainfall activity.

scholarly journals Export of <sup>134</sup>Cs and <sup>137</sup>Cs in the Fukushima river systems at heavy rains by Typhoon Roke in September 2011

2013 ◽  
Vol 10 (2) ◽  
pp. 2767-2790 ◽  
Author(s):  
S. Nagao ◽  
M. Kanamori ◽  
S. Ochiai ◽  
S. Tomihara ◽  
K. Fukushi ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Heavy Rain ◽  
Rain Event ◽  
Normal Flow ◽  
Flow Conditions ◽  
Pulse Input ◽  
Heavy Rain Event ◽  
Coastal Marine ◽  
Rain Events ◽  
Heavy Rains

Abstract. Effects of a heavy rain event on radiocesium export were studied at stations on the Natsui River and the Same River in Fukushima Prefecture, Japan after Typhoon Roke during 21–22 September 2011, six months after the Fukushima Daiichi Nuclear Power Plant accident. Radioactivity of 134Cs and 137Cs in river waters was 0.011–0.098 Bq L−1 at normal flow conditions during July–September in 2011, but it increased to 0.85 Bq L−1 in high flow conditions by heavy rains occurring with the typhoon. The particulate fractions of 134Cs and 137Cs were 21–56% in the normal flow condition, but were close to 100% after the typhoon. These results indicate that the pulse input of radiocesium associated with suspended particles from land to coastal ocean occurred by the heavy rain event. Export flux of 134Cs and 137Cs by the heavy rain accounts for 30–50% of annual radiocesium flux in 2011. Results show that rain events are one factor controlling the transport and dispersion of radiocesium in river watersheds and coastal marine environments.

Impact of a severe rain event on C- and N-DBP precursor removal using IEX

2018 ◽  
Vol 18 (6) ◽  
pp. 2092-2099
Author(s):  
K. Doederer ◽  
Z. Ilieva ◽  
J. Keller
Keyword(s):  
Ion Exchange ◽  
Heavy Rain ◽  
Health Concern ◽  
Rain Event ◽  
Heavy Rain Event ◽  
Removal Capacity ◽  
C And N ◽  
Pre Treatment ◽  
Rain Events ◽  
Magnetic Ion

Abstract During disinfection, dissolved organic matter (DOM) is the major precursor to form disinfection by-products (DBPs), which may be of potential human health concern. Previous research focused on waters of continental climates and less on subtropical environments. However, water sources in subtropical climates are regularly impacted by major rain events during the summer months. This study evaluated the C- and N-DBP precursor removal capacity of two conventional ion exchange (IEX) resins and one magnetic ion exchange (MIEX) resin with a raw water at normal conditions and impacted by a heavy rain event. The rain event introduced 3 mg C/L total organic carbon (TOC) comprised mainly of low to medium molecular weight organics. All three resins were able to remove TOC and DBP precursors (&gt;66%) but being less efficient in reducing turbidity (3–48%) and colour (9–24%). The resin with the smallest bead size was affected the most by the increased medium MW DOM loading resulting in DOM and C-DBP precursor removal performance losses of 10% and 22%. When applied as a pre-treatment for coagulation, MIEX was more efficient in DBP precursor control than coagulation in addressing the additional organic and DBP precursor loading after a heavy rain event.

scholarly journals Sea surface temperature and torrential rains in the Valencia region: modelling the role of recharge areas

2015 ◽  
Vol 15 (7) ◽  
pp. 1677-1693 ◽  
Author(s):  
F. Pastor ◽  
J. A. Valiente ◽  
M. J. Estrela
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Heavy Rain ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Economic Losses ◽  
High Mountain ◽  
Rain Event ◽  
Air Mass ◽  
Rain Events

Abstract. Heavy rain events are frequently recorded in the Western Mediterranean causing economic losses and even human casualties. The Western Mediterranean is a deep and almost closed sea surrounded by high mountain ranges and with little exchange of water with the Atlantic ocean. A main factor in the development of torrential rains is ocean-atmosphere exchanges of heat and moisture that can potentially destabilize air masses travelling over the sea. The study of air mass trajectories previous to the rain event permits the identification of sea areas that could probably contribute to the development or intensification of rainfall. From a previous Mediterranean sea surface temperature climatology, its spatio-temporal distribution patterns have been studied showing two main distribution modes in winter and summer and transitional regimes in spring and autumn. Hence, three heavy precipitation events, for such winter and summer sea temperature regimes and for fall transition, affecting the Valencia region have been selected to study the effect of sea surface temperature in torrential rains. Simulations with perturbed sea surface temperature in different areas along the air mass path were run to compare results with unperturbed simulation. The variation of sea surface temperature in certain areas caused significant changes in model accumulated values and its spatial distribution. Therefore, the existence of areas that at a greater extent favour air-sea interaction leading to the development of torrential rainfall in the Valencia region has been shown. This methodology could be extended to the whole Mediterranean basin to look for such potential recharge areas. The identification of sea areas that contribute to the development or intensification of heavy rain events in the Mediterranean countries could be a useful prognosis and/or monitoring tool.

Investigation of PR and TMI Version 6 and Version 7 Rainfall Algorithms in Landfalling Tropical Cyclones Relative to the NEXRAD Stage-IV Multisensor Precipitation Estimate Dataset

2013 ◽  
Vol 52 (12) ◽  
pp. 2809-2827 ◽  
Author(s):  
Joseph P. Zagrodnik ◽  
Haiyan Jiang
Keyword(s):  
Tropical Cyclones ◽  
Stage Iv ◽  
Tropical Rainfall Measuring Mission ◽  
Heavy Rain ◽  
Light Rain ◽  
Hourly Rainfall ◽  
Wide Range ◽  
Landfalling Tropical Cyclones ◽  
Rain Rates ◽  
Rainfall Estimates

AbstractRainfall estimates from versions 6 (V6) and 7 (V7) of the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) 2A25 and Microwave Imager (TMI) 2A12 algorithms are compared relative to the Next Generation Weather Radar (NEXRAD) Multisensor Precipitation Estimate stage-IV hourly rainfall product. The dataset consists of 252 TRMM overpasses of tropical cyclones from 2002 to 2010 within a 230-km range of southeastern U.S. Weather Surveillance Radar-1988 Doppler (WSR-88D) sites. All rainfall estimates are averaged to a uniform 1/7° square grid. The grid boxes are also divided by their TMI surface designation (land, ocean, or coast). A detailed statistical analysis is undertaken to determine how changes to the TRMM rainfall algorithms in the latest version (V7) are influencing the rainfall retrievals relative to ground reference data. Version 7 of the PR 2A25 is the best-performing algorithm over all three surface types. Over ocean, TMI 2A12 V7 is improved relative to V6 at high rain rates. At low rain rates, the new ocean TMI V7 probability-of-rain parameter creates ambiguity in differentiating light rain (≤0.5 mm h−1) and nonraining areas. Over land, TMI V7 underestimates stage IV more than V6 does at a wide range of rain rates, resulting in an increased negative bias. Both versions of the TMI coastal algorithm are also negatively biased at both moderate and heavy rain rates. Some of the TMI biases can be explained by uncertain relationships between rain rate and 85-GHz ice scattering.

scholarly journals Sea surface temperature and torrential rains in the Valencia region: modelling the role of recharge areas

2015 ◽  
Vol 3 (2) ◽  
pp. 1357-1396 ◽  
Author(s):  
F. Pastor ◽  
J. A. Valiente ◽  
M. J. Estrela
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Heavy Rain ◽  
Western Mediterranean ◽  
Sea Surface ◽  
Economic Losses ◽  
High Mountain ◽  
Rain Event ◽  
Air Mass ◽  
Rain Events

Abstract. Heavy rain events are frequently recorded in the Western Mediterranean causing economic losses and even human casualties. The Western Mediterranean is a deep and almost closed sea surrounded by high mountain ranges and with little exchange of water with the Atlantic ocean. A main factor in the development of torrential rains are ocean-atmosphere exchanges of heat and moisture that can potentially destabilize air masses travelling over the sea. The study of air mass trajectories previous to the rain event permits the identification of sea areas that could probably contribute to the development or intensification of rainfall. From a previous Mediterranean sea surface temperature climatology, its spatio-temporal distribution patterns have been studied showing two main distribution modes in winter and summer and transitional regimes in spring and autumn. Hence, three heavy precipitation events, for such winter and summer sea temperature regimes and for fall transition, affecting the Valencia region have been selected to study the effect of sea surface temperature in torrential rains. Simulations with perturbed sea surface temperature in different areas along the air mass path were run to compare results with unperturbed simulation. The variation of sea surface temperature in certain areas caused significant changes in model accumulated values and its spatial distribution. Therefore, the existence of recharge areas where air–sea interaction favors the development of torrential rainfall in Valencia region has been shown. This methodology could be extended to the whole Mediterranean basin to look for such potential recharge areas. The identification of sea areas that contribute to the development or intensification of heavy rain events in the Mediterranean countries could be a useful prognosis and/or monitoring tool.

scholarly journals A TRMM-Calibrated infrared technique for rainfall estimation: application on rain events over eastern Mediterranean

2006 ◽  
Vol 7 ◽  
pp. 181-188 ◽  
Author(s):  
H. Feidas ◽  
G. Kokolatos ◽  
A. Negri ◽  
M. Manyin ◽  
N. Chrysoulakis
Keyword(s):  
Eastern Mediterranean ◽  
Regional Scale ◽  
Tropical Rainfall Measuring Mission ◽  
Rain Gauge ◽  
Tropical Areas ◽  
Trmm Precipitation ◽  
Remote Sensing Techniques ◽  
Rain Events ◽  
Rain Rates ◽  
Rain Gauge Network

Abstract. The aim is to evaluate the use of a satellite infrared (IR) technique for estimating rainfall over the eastern Mediterranean. The Convective-Stratiform Technique (CST), calibrated by coincident, physically retrieved rain rates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), is applied over the Eastern Mediterranean for four rain events during the six month period of October 2004 to March 2005. Estimates from this technique are verified over a rain gauge network for different time scales. Results show that PR observations can be applied to improve IR-based techniques significantly in the conditions of a regional scale area by selecting adequate calibration areas and periods. They reveal, however, the limitations of infrared remote sensing techniques, originally developed for tropical areas, when applied to precipitation retrievals in mid-latitudes.

scholarly journals Comparison of Two Jason-1 Altimeter Precipitation Detection Algorithms with Rain Estimates from the TRMM Microwave Imager

2005 ◽  
Vol 22 (6) ◽  
pp. 782-794 ◽  
Author(s):  
N. Tran ◽  
E. Obligis ◽  
F. Ferreira
Keyword(s):  
Cross Sections ◽  
Tropical Rainfall Measuring Mission ◽  
False Alarms ◽  
Dual Frequency ◽  
Detection Algorithms ◽  
Radar Cross Sections ◽  
Microwave Imager ◽  
Rain Events ◽  
Trmm Microwave Imager ◽  
Rain Rates

Abstract This paper evaluates and compares the ability of two different Jason-1 dual-frequency altimeter algorithms (referred as Tournadre’s and Quartly’s rain flags, respectively) to detect rain events in order to flag rain-contaminated altimeter range measurements. They are based on departures from a defined relationship between the Ku- and C-band radar cross sections observed in no-rain conditions. The algorithms’ performances were assessed via collocations of these dual-frequency-based estimates with rain rates and a rain–no-rain flag from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). The Jason-1–TMI analysis is built upon a yes–no discrimination, which is helpful in providing good insight into the altimeter rain detection flags’ efficiency through estimations of the percentages of hits, misses, false alarms, and correct negatives when compared with TMI measurements. Tournadre’s rain flag, based on a combination of altimeter and radiometer data, gives the best match with TMI estimates, compared to Quartly’s, and also has a higher sensitivity to low-intensity rainfall.

scholarly journals Validation of TRMM Precipitation Radar through Comparison of Its Multiyear Measurements with Ground-Based Radar

2009 ◽  
Vol 48 (4) ◽  
pp. 804-817 ◽  
Author(s):  
Liang Liao ◽  
Robert Meneghini
Keyword(s):  
Tropical Rainfall Measuring Mission ◽  
Heavy Rain ◽  
Radar Data ◽  
Precipitation Radar ◽  
Convective Storms ◽  
Conditional Mean ◽  
Conditional Basis ◽  
Trmm Precipitation ◽  
Rain Rates ◽  
Overlap Area

Abstract A procedure to accurately resample spaceborne and ground-based radar data is described and then is 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, nonattenuated WSR at Melbourne, Florida, for the period 1998–2007, the calibration of the 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 at which 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.

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