scholarly journals ESTUDO DE CASO DE CONTRIBUIÇÃO DO FLUXO DE UMIDADE EM EVENTO DE PRECIPITAÇÃO INTENSA OCORRIDO NO LESTE DO NORDESTE DO BRASIL EM MAIO DE 2017

2019 ◽  
Vol 12 (5) ◽  
pp. 1844
Author(s):  
Rosária Rodrigues Ferreira ◽  
Marcele De Jesus Correa ◽  
Kellen Carla Lima ◽  
Maytê Duarte Leal Coutinho
Keyword(s):  
Extreme Event ◽  
Temporal Distribution ◽  
Heavy Rainfall Event ◽  
Rainfall Regime ◽  
Eastern Region ◽  
Weather Forecasts ◽  
Rain Gauges ◽  
Medium Range ◽  
Disaster Monitoring

A observação de distribuição espacial e temporal do regime de chuvas da região Nordeste do Brasil (NEB) torna-se um desafio devido sua grande variabilidade no tempo e no espaço. Durante o período de 25 a 29 de maio de 2017 foram registrados casos de chuvas intensas na parte leste do NEB, principalmente entre os estados de Alagoas e de Pernambuco. Desta forma, objetivo deste trabalho consistiu em verificar a contribuição do fluxo de umidade associada ao evento de precipitação severa ocorrido na região leste do NEB Especificamente, pretende-se averiguar as características física e sinótica de referido evento. Para tanto, foram utilizados dados de estações pluviométricas automáticas do Centro Nacional de Monitoramento e Alertas de Desastres Naturais (CEMADEN), imagens de satélite GOES-13 e reanálises pertencentes ao European Centre for Medium-Range Weather Forecasts (ECMWF), do conjunto de reanálise ERA-5. Os resultados obtidos desta pesquisa conseguiram mostrar que o transporte de umidade integrado na vertical sobre a costa leste do NEB foi bastante intenso durante o período em que o sistema de precipitação esteve no estágio de maturação.Palavras-chave: NEB ERA-5; Chuva intensa; Transporte de umidade.  Contribution of moisture flows in heavy rainfall event occurred in eastern Northeast Brazil in May 2017: A case study A B S T R A C TThe observation of spatial and temporal distribution of the rainfall regime of the Northeast of Brazil (NEB) becomes a challenge due to its great variability in time and space. In the period from May 25 to 29, 2017, heavy rains occurred in the eastern part of the NEB, mainly between the states of Alagoas and Pernambuco. Thus, the objective of this work was to verify the contribution of the moisture flow associated to the event of severe precipitation occurred in the eastern region of the NEB. Specifically, it is intended to ascertain the physical and synoptic characteristics of said event. In order to do so, we used data from automatic rain gauges of the National Center for Natural Disaster Monitoring and Alarms (CEMADEN), GOES-13 satellite images and reanalysis from the European Center for Medium-Range Weather Forecasts (ECMWF) ERA-5. The main results showed that the vertical moisture transport presented strong nuclei of moisture convergence in the Atlantic Ocean towards the study area, when the precipitation system was in the maturation stage.Keywords: Transport of moisture; Synoptic analysis; Extreme event; ERA-5.

scholarly journals Contribuição dos fluxos de umidade em evento de precipitação intensa ocorrido no leste do Nordeste do Brasil em maio de 2017: Um estudo de caso (Contribution of moisture flows in heavy rainfall event occurred in eastern Northeast Brazil in May 2017: A case study)

2019 ◽  
Vol 12 (5) ◽  
pp. 1703
Author(s):  
Marcele de Jesus Correa ◽  
Kellen Carla Lima ◽  
Maytê Duarte Leal Coutinho
Keyword(s):  
Extreme Event ◽  
Temporal Distribution ◽  
Heavy Rainfall Event ◽  
Rainfall Regime ◽  
Eastern Region ◽  
Weather Forecasts ◽  
Rain Gauges ◽  
Medium Range ◽  
Disaster Monitoring

A observação de distribuição espacial e temporal do regime de chuvas da região Nordeste do Brasil (NEB) torna-se um desafio devido sua grande variabilidade no tempo e no espaço. No período de 25 a 29 de maio de 2017 foram registrados casos de chuvas intensas na parte leste do NEB, principalmente entre os estados de Alagoas e de Pernambuco. Desta forma, objetivo deste trabalho consistiu em verificar a contribuição dos fluxos de umidade associada ao evento de precipitação severa ocorrido na região leste do NEB. Especificamente, pretende-se averiguar as características física e sinótica de referido evento. Para tanto, foram utilizados dados de estações pluviométricas automáticas do Centro Nacional de Monitoramento e Alertas de Desastres Naturais (CEMADEN), imagens de satélite GOES-13 e reanálises pertencentes ao European Centre for Medium-Range Weather Forecasts (ECMWF), do conjunto de reanálise ERA-5. Os  principais resultados mostraramque o transporte de umidade integrado na vertical, apresentou fortes núcleos de convergência de umidade no oceano Atlântico se deslocaram em direção à área do estudo, quando o sistema de precipitação esteve no estágio de maturação.Palavras-chave:  Transporte de umidade; Análise sinótica; Evento extremo; ERA-5.A B S T R A C TThe observation of spatial and temporal distribution of the rainfall regime of the Northeast of Brazil (NEB) becomes a challenge due to its great variability in time and space. In the period from May 25 to 29, 2017, heavy rains occurred in the eastern part of the NEB, mainly between the states of Alagoas and Pernambuco. Thus, the objective of this work was to verify the contribution of the moisture flow associated to the event of severe precipitation occurred in the eastern region of the NEB. Specifically, it is intended to ascertain the physical and synoptic characteristics of said event. In order to do so, we used data from automatic rain gauges of the National Center for Natural Disaster Monitoring and Alarms (CEMADEN), GOES-13 satellite images and reanalysis from the European Center for Medium-Range Weather Forecasts (ECMWF) ERA-5. The main results showed that the vertical moisture transport presented strong nuclei of moisture convergence in the Atlantic Ocean towards the study area, when the precipitation system was in the maturation stage.Keywords: Transport of moisture; Synoptic analysis; Extreme event; ERA-5.

Evaluation of Global Forecast System (GFS) Medium-Range Precipitation Forecasts in the Nile River Basin

2021 ◽  
Author(s):  
Haowen Yue ◽  
Mekonnen Gebremichael ◽  
Vahid Nourani
Keyword(s):  
Temporal Dynamics ◽  
Disease Outbreaks ◽  
Rain Gauge ◽  
Global Forecast System ◽  
Forecast System ◽  
Forecast Performance ◽  
Weather Forecasts ◽  
Rain Gauges ◽  
Basin Scale ◽  
Medium Range

Abstract Reliable weather forecasts are valuable in a number of applications, such as, agriculture, hydropower, and weather-related disease outbreaks. Global weather forecasts are widely used, but detailed evaluation over specific regions is paramount for users and operational centers to enhance the usability of forecasts and improve their accuracy. This study presents evaluation of the Global Forecast System (GFS) medium-range (1 day – 15 day) precipitation forecasts in the nine sub-basins of the Nile basin using NASA’s Integrated Multi-satellitE Retrievals (IMERG) “Final Run” satellite-gauge merged rainfall observations. The GFS products are available at a temporal resolution of 3-6 hours, spatial resolution of 0.25°, and its version-15 products are available since 12 June 2019. GFS forecasts are evaluated at a temporal scale of 1-15 days, spatial scale of 0.25° to all the way to the sub-basin scale, and for a period of one year (15 June 2019 – 15 June 2020). The results show that performance of the 1-day lead daily basin-averaged GFS forecast performance, as measured through the modified Kling-Gupta Efficiency (KGE), is poor (0 < KGE < 0.5) for most of the sub-basins. The factors contributing to the low performance are: (1) large overestimation bias in watersheds located in wet climate regimes in the northern hemispheres (Millennium watershed, Upper Atbara & Setit watershed, and Khashm El Gibra watershed), and (2) lower ability in capturing the temporal dynamics of watershed-averaged rainfall that have smaller watershed areas (Roseires at 14,110 sq. km and Sennar at 13,895 sq. km). GFS has better bias for watersheds located in the dry parts of the northern hemisphere or wet parts of the southern hemisphere, and better ability in capturing the temporal dynamics of watershed-average rainfall for large watershed areas. IMERG Early has better bias than GFS forecast for the Millennium watershed but still comparable and worse bias for the Upper Atbara & Setit, and Khashm El Gibra watersheds. The variation in the performance of the IMERG Early could be partly explained by the number of rain gauges used in the reference IMERG Final product, as 16 rain gauges were used for the Millennium watershed but only one rain gauge over each Upper Atbara & Setit, and Khashm El Gibra watershed. A simple climatological bias-correction of IMERG Early reduces in the bias in IMERG Early over most watersheds, but not all watersheds. We recommend exploring methods to increase the performance of GFS forecasts, including post-processing techniques through the use of both near-real-time and research-version satellite rainfall products.

scholarly journals Nonhomogeneous Boosting for Predictor Selection in Ensemble Postprocessing

2016 ◽  
Vol 145 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Jakob W. Messner ◽  
Georg J. Mayr ◽  
Achim Zeileis
Keyword(s):  
Regression Coefficients ◽  
Maximum Temperature ◽  
Ensemble Forecasts ◽  
Forecast Performance ◽  
Weather Forecasts ◽  
Medium Range ◽  
Important Input ◽  
Boosting Algorithm ◽  
Input Variables

Abstract Nonhomogeneous regression is often used to statistically postprocess ensemble forecasts. Usually only ensemble forecasts of the predictand variable are used as input, but other potentially useful information sources are ignored. Although it is straightforward to add further input variables, overfitting can easily deteriorate the forecast performance for increasing numbers of input variables. This paper proposes a boosting algorithm to estimate the regression coefficients, while automatically selecting the most relevant input variables by restricting the coefficients of less important variables to zero. A case study with ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) shows that this approach effectively selects important input variables to clearly improve minimum and maximum temperature predictions at five central European stations.

scholarly journals FORMATION CONDITIONS OF WARM-SEASON STORM RAINFALL IN PERM REGION

2020 ◽  
Vol 30 (3) ◽  
pp. 295-306
Author(s):  
N.A. Kalinin ◽  
B.A. Sivkov ◽  
A.V. Dmitriev
Keyword(s):  
Warm Season ◽  
Temporal Distribution ◽  
Average Intensity ◽  
Weather Forecasts ◽  
Medium Range ◽  
Formation Conditions ◽  
Storm Rainfall ◽  
Perm Region ◽  
Instability Indices

The article deals with the issue of the formation conditions and possibility of predicting storm rainfall in the territory of Perm region using atmospheric instability indices. In the course of the study, the spatial and temporal distribution of storm rainfall cases was assessed, as well as the most favorable values of meteorological parameters and synoptic situations contributing to rainfall were determined. The instability indices were calculated based on the ERA-Interim reanalysis of the spectral model of the European Center for Medium-Range Weather Forecasts (ECMWF) and the reanalysis of the American hydrodynamic model Climate Forecast System (CFS). On the basis of correlation analysis, the dependence of instability indices on the amount and average intensity of storm rainfall was estimated. The critical values of the considered instability indices were determined and corrected in relation to the studied territory. The study showed that the most frequent storm rainfall is observed in June and July in the afternoon and evening. It was found that storm rainfall is mainly associated with the passage of cold fronts. The assessment of the quality of instability indices has shown the feasibility of their use for the forecast and diagnosis of storm precipitation, including in the gradation of this dangerous phenomenon.

scholarly journals HOAPS and ERA-Interim precipitation over sea: Validation against shipboard in-situ measurements

2016 ◽  
Author(s):  
Karl Bumke ◽  
Gert König-Langlo ◽  
Julian Kinzel ◽  
Marc Schröder
Keyword(s):  
Reanalysis Data ◽  
Data Sets ◽  
Weather Forecasts ◽  
Rain Gauges ◽  
Medium Range ◽  
Temporal And Spatial ◽  
The Tropics ◽  
Along Track ◽  
Spatial Threshold

Abstract. The satellite derived HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite data) and ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis data sets have been validated against in-situ precipitation measurements from ship rain gauges and optical disdrometers over the open-ocean by applying a statistical analysis for binary forecasts. For this purpose collocated pairs of data were merged within a certain temporal and spatial threshold into single events, according to the satellites' overpass, the observation and the forecast times. HOAPS detects the frequency of precipitation well, while ERA-Interim strongly overestimates it, especially in the tropics and subtropics. Although precipitation rates are difficult to compare because along-track point measurements are collocated with areal estimates and the numbers of available data are limited, we find that HOAPS underestimates precipitation rates, while ERA-Interim's Atlantic-wide average precipitation rate is close to measurements. However, regionally averaged over latitudinal belts, there are deviations between the observed mean precipitation rates and ERA-Interim. The most obvious ERA-Interim feature is an overestimation of precipitation in the area of the intertropical convergence zone and the southern sub-tropics over the Atlantic Ocean. For a limited number of snow measurements by optical disdrometers it can be concluded that both HOAPS and ERA-Interim are suitable to detect the occurrence of solid precipitation.

scholarly journals HOAPS and ERA-Interim precipitation over the sea: validation against shipboard in situ measurements

2016 ◽  
Vol 9 (5) ◽  
pp. 2409-2423 ◽  
Author(s):  
Karl Bumke ◽  
Gert König-Langlo ◽  
Julian Kinzel ◽  
Marc Schröder
Keyword(s):  
Reanalysis Data ◽  
Data Sets ◽  
Weather Forecasts ◽  
Rain Gauges ◽  
Medium Range ◽  
Temporal And Spatial ◽  
The Tropics ◽  
Along Track ◽  
Spatial Threshold

Abstract. The satellite-derived HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data) and ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis data sets have been validated against in situ precipitation measurements from ship rain gauges and optical disdrometers over the open ocean by applying a statistical analysis for binary estimates. For this purpose collocated pairs of data were merged within a certain temporal and spatial threshold into single events, according to the satellites' overpass, the observation and the ERA-Interim times. HOAPS detects the frequency of precipitation well, while ERA-Interim strongly overestimates it, especially in the tropics and subtropics. Although precipitation rates are difficult to compare because along-track point measurements are collocated with areal estimates and the number of available data are limited, we find that HOAPS underestimates precipitation rates, while ERA-Interim's Atlantic-wide average precipitation rate is close to measurements. However, when regionally averaged over latitudinal belts, deviations between the observed mean precipitation rates and ERA-Interim exist. The most obvious ERA-Interim feature is an overestimation of precipitation in the area of the intertropical convergence zone and the southern subtropics over the Atlantic Ocean. For a limited number of snow measurements by optical disdrometers, it can be concluded that both HOAPS and ERA-Interim are suitable for detecting the occurrence of solid precipitation.

scholarly journals Rainfall Regime of a Mountainous Mediterranean Region: Statistical Analysis at Short Time Steps

2012 ◽  
Vol 51 (3) ◽  
pp. 429-448 ◽  
Author(s):  
Gilles Molinié ◽  
Davide Ceresetti ◽  
Sandrine Anquetin ◽  
Jean Dominique Creutin ◽  
Brice Boudevillain
Keyword(s):  
Daily Rainfall ◽  
Large River ◽  
Rain Gauge ◽  
Heavy Rainfall Event ◽  
Rainfall Regime ◽  
Study Region ◽  
Rain Gauge Data ◽  
Rain Gauges ◽  
Gauge Data ◽  
The Difference

AbstractThis paper presents an analysis of the rainfall regime of a Mediterranean mountainous region of southeastern France. The rainfall regime is studied on temporal scales from hourly to yearly using daily and hourly rain gauge data of 43 and 16 years, respectively. The domain is 200 × 200 km2 with spatial resolution of hourly and daily rain gauges of about 8 and 5 km, respectively. On average, yearly rainfall increases from about 0.5 m yr−1 in the large river plain close to the Mediterranean Sea to up to 2 m yr−1 over the surrounding mountain ridges. The seasonal distribution is also uneven: one-third of the cumulative rainfall occurs during the autumn season and one-fourth during the spring. At finer time scales, rainfall is studied in terms of rain–no-rain intermittency and nonzero intensity. The monthly intermittency (proportion of dry days per month) and the daily intermittency (proportion of dry hours per day) is fairly well correlated with the relief. The higher the rain gauges are, the lower the monthly and daily intermittencies are. The hourly and daily rainfall intensities are analyzed in terms of seasonal variability, diurnal cycle, and spatial pattern. The difference between regular and heavy-rainfall event is depicted by using both central parameters and maximum values of intensity distributions. The relationship between rain gauge altitudes and rainfall intensity is grossly inverted relative to intermittency and is also far more complex. The spatial and temporal rainfall patterns depicted from rain gauge data are discussed in the light of known meteorological processes affecting the study region.

scholarly journals Spatial–temporal distribution of heavy precipitation over Ukraine during 1979-2019 according to the ERA5 reanalysis

2020 ◽  
pp. 50-59
Author(s):  
A. B. Semerhei-Chumachenko ◽  
K. L. Slobodianyk
Keyword(s):  
Extreme Precipitation ◽  
Temporal Distribution ◽  
Heavy Precipitation ◽  
Temporal Analysis ◽  
Rain Intensity ◽  
Synoptic Classification ◽  
Weather Forecasts ◽  
European Centre ◽  
Carpathian Region ◽  
Medium Range

The paper presents the results of research of heavy and extreme precipitation in the form of rain (> 50 mm / 12 h) and snow (> 20 mm / 12 h) using the data from the atmospheric reanalysis ERA5 for the period of 1979-2019. According to the data of the European Centre for Medium-Range Weather Forecasts obtained through the numerical modeling and resulting from the data assimilation at the nodes of a regular grid with a spatial resolution of 0,25°×0,25°, there are 131 and 136 days with rain and snow during which precipitation intensity reached the criteria of meteorological phenomena of the 2nd and 3rd levels of danger. It was discovered that the last 40 years in Ukraine proved to have a tendency of an increased number of cases of heavy snowfall, and a slightly decreased number of heavy rains. The research pays considerable attention to the spatial-temporal analysis of the frequency and intensity of heavy rainfall with consideration of geographical factors. It determines the seasonal course of heavy and extreme precipitation, the maximum and minimum values of which did not differ from the climatic standard values observed during meteorological observations. Rainfalls with precipitation rates of more than 50 mm over 12 hours were observed almost over the entire territory of Ukraine and the maximum frequency zones were detected over the Carpathian Mountains, Donetsk Ridge, Podolsk Upland, and the south-western part of the country. Heavy snowfalls with more than 20 mm precipitation over 12 hours mostly occurred in the Carpathian region. The analysis of the geographical distribution revealed a center with maximum values of rain intensity (120-133 mm over 12 h) off the coast of the Sea of Azov, and the heaviest snowfalls (34-38 mm over 12 h) mainly formed in the Carpathian region. The paper established the types of elementary circulation mechanisms of Dzerdzeevsky’s synoptic classification of Northern Hemisphere atmospheric circulation. These types, when continuous in nature, resulted in a significantly increased precipitation in the form of rain and snow. According to the reanalysis data, cases with the maximum rain intensity were found over the period of 23 to 27 July 2008 when a catastrophic flood was observed in the Ukrainian Carpathians. This fact indicates that the structure of the field of heavy precipitation over the territory of Ukraine was adequately reproduced by the respective model of the European Centre for Medium-Range Weather Forecasts.

scholarly journals A Diagnostic Case Study of Mei-Yu Frontal Retreat and Associated Low Development near Taiwan

2016 ◽  
Vol 144 (6) ◽  
pp. 2327-2349 ◽  
Author(s):  
Chung-Chieh Wang ◽  
George Tai-Jen Chen ◽  
Kuok-Hou Ho
Keyword(s):  
Northern South China Sea ◽  
Cold Side ◽  
Weather Forecasts ◽  
Convective Systems ◽  
Physical Mechanisms ◽  
Medium Range ◽  
Mesoscale Convective ◽  
Southern Taiwan ◽  
Second Period

Abstract After advancing southward across Taiwan and becoming quasi stationary, a mei-yu front moved north again and led to a second period of significant rainfall during 13–14 June 2012. Associated with this frontal retreat, a meso-α-scale low pressure developed to the southwest of Taiwan, in the proximity of organized mesoscale convective systems (MCSs) along and south of the front over the northern South China Sea. In this study, using mainly the European Centre for Medium-Range Weather Forecasts gridded analyses, the physical mechanisms of this frontal retreat are investigated and diagnosed, with a focus on the initial retreat and the role played by the deepening frontal low. The diagnoses employing the vorticity equation and frontogenetical function both indicate that the appearance of southerly winds, and thus the retrogression of cold air north of the front was the cause of the initial frontal retreat, consistent with earlier studies. The potential vorticity diagnosis using the piecewise inversion technique further confirms that the deepening low over the southern Taiwan Strait provided the southerly winds east of Taiwan where the retreat started, while the low itself intensified in response to the persistent latent heating by the active and organized MCSs. Thus, the northerly winds on the cold side of the front near Taiwan were replaced by southerly winds, and the mei-yu front in the present case retreated and essentially became a warm front. While mei-yu frontal retreats near Taiwan are more frequent than previously recognized, the present case was the most significant event in three seasons during 2012–14.

scholarly journals Uncertainties in rainfall retrievals from ground-based weather radar: overview, case study, and simulation experiment

2006 ◽  
Vol 3 (4) ◽  
pp. 2385-2436
Author(s):  
R. Uijlenhoet ◽  
S. H. van der Wielen ◽  
A. Berne
Keyword(s):  
Simulation Experiment ◽  
Temporal Distribution ◽  
Weather Radar ◽  
Rain Gauge ◽  
Radar Rainfall ◽  
Rain Gauges ◽  
Weather Radars ◽  
Wide Range ◽  
Rainfall Retrieval

Abstract. Because rainfall constitutes the main source of water for the terrestrial hydrological processes, accurate and reliable measurement and prediction of its spatial and temporal distribution over a wide range of scales is an important goal for hydrology. We investigate the potential of ground-based weather radar to provide such measurements through a detailed analysis of the associated observation uncertainties. First, a historical perspective on measuring the space-time distribution of rainfall, from the rain gauge to the radar era, is presented. Subsequently, we provide an overview of the various errors and uncertainties affecting radar rainfall retrievals. As an example, we present a case study of the relation between measurements from an operational C-band weather radar and a network of tipping bucket rain gauges as a function of range. Finally, a recently developed stochastic model of range profiles of rainfall microstructure is employed in a simulation experiment designed to investigate the rainfall retrieval uncertainties associated with weather radars operating in different widely used frequency bands.

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