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Previsões climáticas sazonais sobre o Brasil: avaliação do RegCM3 aninhado no modelo global CPTEC/COLA; Seasonal climatic forecast over Brazil: evaluation of the RegCM3 model nested to the CPTEC/COLA global model

MACHADO, Rubinei Dorneles; ROCHA, Rosmeri Porfírio da
Fonte: Sociedade Brasileira de Meteorologia Publicador: Sociedade Brasileira de Meteorologia
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.83%
Este trabalho avalia o desempenho de previsões sazonais do modelo climático regional RegCM3, aninhado ao modelo global CPTEC/COLA. As previsões com o RegCM3 utilizaram 60 km de resolução horizontal num domínio que inclui grande parte da América do Sul. As previsões do RegCM3 e CPTEC/COLA foram avaliadas utilizando as análises de chuva e temperatura do ar do Climate Prediction Center (CPC) e National Centers for Enviromental Prediction (NCEP), respectivamente. Entre maio de 2005 e julho de 2007, 27 previsões sazonais de chuva e temperatura do ar (exceto a temperatura do CPTEC/COLA, que possui 26 previsões) foram avaliadas em três regiões do Brasil: Nordeste (NDE), Sudeste (SDE) e Sul (SUL). As previsões do RegCM3 também foram comparadas com as climatologias das análises. De acordo com os índices estatísticos (bias, coeficiente de correlação, raiz quadrada do erro médio quadrático e coeficiente de eficiência), nas três regiões (NDE, SDE e SUL) a chuva sazonal prevista pelo RegCM3 é mais próxima da observada do que a prevista pelo CPTEC/COLA. Além disto, o RegCM3 também é melhor previsor da chuva sazonal do que da média das observações nas três regiões. Para temperatura, as previsões do RegCM3 são superiores às do CPTEC/COLA nas áreas NDE e SUL...

Previsão de chuva com auxílio de radar de tempo visando a um sistema de alerta antecipado de cheias em áreas urbanas; Precipitation forecast aided by weather radar for early warning system of urban floods

Gonçalves, Micheli Fernandes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/06/2009 PT
Relevância na Pesquisa
56.98%
Para reduzir as perdas humanas e materiais durante as inundações, é possível realizar estudo conciso da previsão de chuva, etapa principal de um sistema de alerta antecipado de inundação. O uso de informações de radar de tempo, quando acopladas a modelos de previsão de precipitação baseados fisicamente, pode contribuir para o monitoramento e previsão de episódios de chuva intensa. Desta forma, a previsão de chuva, baseada no uso de informações de radar, juntamente com um modelo conceitual de previsão hidrometeorológica, foi descrita neste trabalho. Teve-se por objetivo aperfeiçoar as previsões de chuva de curtíssimo prazo (poucos minutos), que acopladas a um modelo chuva-vazão, podem ser usadas em sistemas de alerta antecipado. O modelo hidrometeorológico adotado, que considera uma nuvem hipotética unidimensional vertical, foi inicialmente desenvolvido por Georgakakos e Bras (1984a) e ampliado, neste trabalho. Para tal, adotou-se o uso das informações de Topo dos Ecos para determinação da altura das nuvens e considerou-se que a componente do modelo relativa à massa de água líquida no interior da nuvem corresponde à estimativa do conteúdo de água líquida integrado verticalmente (VIL) efetuada por radar. Para eventos de natureza frontal quente e convectiva...

Previsão de chuva a curtíssimo prazo na área de abrangência do radar meteorológico de São Paulo; Rainfall short-term forecast in the surveillance area of São Paulo weather radar.

Farias, José Felipe da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/09/2009 PT
Relevância na Pesquisa
46.92%
A avaliação da previsão de chuva a curtíssimo prazo com até 3 horas de antecedência na área de cobertura do RSP para diferentes tipos de sistemas precipitantes, principalmente os associados às enchentes e deslizamentos na RMSP, foi realizada por meio de um modelo advectivo a partir do campo de vento 2D médio e da velocidade dos campos das taxas de precipitação estimados com o radar e um Esquema Numérico de Terceira Ordem Corrente Acima (ENTOCA). O ENTOCA utiliza um vetor com deslocamento mantido constante. O desempenho da previsão para precipitação acumulada num determinado intervalo de tempo foi avaliado pelo Índice de Sucesso Crítico (CSI), Probabilidade de Detecção (POD) e Razão de Falsos Alarmes (FAR). Quantitativamente, a acurácia da previsão foi avaliada por meio do Erro Quadrático Médio (EQM). O coeficiente de correlação mostrou que a qualidade da previsão decresce ao longo do tempo, com maior previsibilidade para os sistemas estratiformes do que para os convectivos. O ENTOCA não considera a evolução espaço-temporal dos sistemas precipitantes durante a extrapolação do campo das taxas de precipitação. Em geral, constatou-se uma subestimativa da precipitação acumulada. As previsões também apresentaram maior desempenho para até 90 minutos e menor...

Extremos de precipitação diária em Belém, Pará, e estrutura vertical da atmosfera; Extreme daily rainfall in Belém, Pará, and vertical structure of atmosphere

Camponogara, Glauber
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/03/2012 PT
Relevância na Pesquisa
36.56%
Diversas atividades ligados ao gerenciamento de recursos hídricos necessitam da previsão de acumulados diários de chuva extremos. Entretanto, grande parte dos modelos utilizados operacionalmente apresentam uma tendência a subestimar os extremos de precipitação mesmo com apenas 24 horas de antecedência. Existem diversas razões para esse tipo de erro de previsão tais como, limitações nas parametrizações de convecção para modelos com resolução de dezenas de quilômetros e a não inclusão do efeito de aerossóis como núcleos de condensação de gotas de nuvens nos modelos de grande escala. Dentro desse contexto, este trabalho tem como objetivo analisar situações de eventos extremos de precipitação na região de Belém, Pará, onde o regime de precipitação é modulado, principalmente, pela brisa marítima, linhas de instabilidade, distúrbios ondulatório de leste, zona de convergência intertropical, alta da Bolívia e Vórtices Ciclônicos de Altos Níveis (VCAN). A abordagem será de identificação de perfis verticais cinemáticos e termodinâmicos típicos de eventos extremos de precipitação diária em Belém, Pará. Para esse fim, escolheu-se fazer uma análise de dados de radiossondagem e precipitação utilizando as Funções Ortogonais Empíricas (EOF - Empirical Orthogonal Functions combinadas e verificar como o Brazilian developments on the Regional Atmospheric Modeling System (BRAMS) simula características básicas de chuva acumulada diária. A variância explicada das EOF calculadas a partir do conjunto de variáveis acumulado diário de precipitação (acpcp)...

Subsídios à operação de reservatórios baseada na previsão de variáveis hidrológicas

Bravo, Juan Martín
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
26.6%
Diversas atividades humanas são fortemente dependentes do clima e da sua variabilidade, especialmente aquelas relacionadas ao uso da água. A operação integrada de reservatórios com múltiplos usos requer uma série de decisões que definem quanta água deve ser alocada, ao longo do tempo para cada um dos usos, e quais os volumes dos reservatórios a serem mantidos. O conhecimento antecipado das condições climáticas resulta de vital importância para os operadores de reservatórios, pois o insumo dos reservatórios é a vazão dos rios, que por sua vez é dependente de condições atmosféricas e hidrológicas em diferentes escalas de tempo e espaço. A pesquisa trata sobre três importantes elementos de subsídio à tomada de decisão na operação de reservatórios baseada na previsão de variáveis hidrológicas: (a) as previsões de vazão de curto prazo; (b) as previsões de precipitação de longo prazo e (c) as medidas de desempenho das previsões. O reservatório de Furnas, localizado na bacia do Rio Grande, em Minas Gerais, foi selecionado como estudo de caso devido, principalmente, à disponibilidade de previsões quantitativas de chuva e pela importância desse reservatório na região analisada. A previsão de curto prazo de vazão com base na precipitação foi estimada com um modelo empírico (rede neural artificial) e a previsão de precipitação foi obtida pelo modelo regional ETA. Uma metodologia de treinamento e validação da rede neural artificial foi desenvolvida utilizando previsões perfeitas de chuva (considerando a chuva observada como previsão) e utilizando o maior número de dados disponíveis...

A study of intense rainfall events in Madeira Island using numerical Models

Couto, Flavio; Salgado, Rui; Dasari, Hari; Costa, Maria João
Fonte: EGU Publicador: EGU
Tipo: Aula
ENG
Relevância na Pesquisa
36.48%
Located in Atlantic Ocean, the Madeira Island is the largest island of the Madeira archipelago, with surface area about 737 km2, an approximately E–W elongated form and a maximum altitude of 1861m. This archipelago is a volcanic complex, with peculiar relief and climate as described by many researchers. In recent times, intense rainfall events in Madeira Island have occurred, resulting in several economical and social damages. Nowadays, the use of well defined dynamics and different physical processes in high resolution numerical models are becoming popular to predict the isolated heavily extreme rainfall episodes. These type of events that may be predicted by the high resolution numerical weather prediction models, basically depend on the design of the model, especially choice of the domain size, horizontal and vertical grid resolution, time step and usage of different physical processes. Therefore, this study aims at analyzing the main characteristics associated to the intense precipitation events in Madeira Island using numerical simulations. In this study we used the Weather Research Forecasting (WRF-ARW) model developed and distributed through the National Center for Atmospheric Research (NCAR), as well as the MESOscale Non-Hydrostatic model (MESO-NH) jointly developed by Météo-France and the Laboratoire d’Aérologie. Initial and boundary conditions are obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) forecast models. The events were simulated using nested grids in a two-way interactive mode...

Forecast of Dengue Incidence Using Temperature and Rainfall

Hii, Yien Ling; Zhu, Huaiping; Ng, Nawi; Ng, Lee Ching; Rocklöv, Joacim
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 29/11/2012 EN
Relevância na Pesquisa
26.52%
Without effective drugs or a vaccine, vector control remains the only method of controlling dengue fever outbreaks in Singapore. Based on our previous findings on the effects of weather on dengue cases and optimal timing for issuing dengue early warning in Singapore, the purpose of this study was to develop a dengue forecasting model that would provide early warning of a dengue outbreak several months in advance to allow sufficient time for effective control to be implemented. We constructed a statistical model using weekly mean temperature and rainfall. This involved 1) identifying the optimal lag period for forecasting dengue cases; 2) developing the model that described past dengue distribution patterns; 3) performing sensitivity tests to analyze whether the selected model could detect actual outbreaks. Finally, we used the selected model to forecast dengue cases from 2011–2012 week16 using weather data alone. Our model forecasted for a period of 16 weeks with high sensitivity in distinguishing between an outbreak and a non-outbreak. We conclude that weather can be an important factor for providing early warning of dengue epidemics, long term sustainability of forecast precision is challenging considering the complex dynamics of disease transmission.

An??lise harm??nica dos totais de chuvas mensais de regi??es homog??neas do Estado do Rio Grande do Sul; Harmonic analysis of the total rainfall monthly of homogeneous regions of the state of Rio Grande do Sul

CARDOSO, Daniel Souza
Fonte: Universidade Federal de Pelotas; Meteorologia; Programa de P??s-gradua????o em Meteorologia; UFPel; BR Publicador: Universidade Federal de Pelotas; Meteorologia; Programa de P??s-gradua????o em Meteorologia; UFPel; BR
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.73%
Whereas the State of Rio Grande do Sul (RS), have an economy directly dependent on agriculture and livestock sectors, which in different studies are reported as dependent on the variability of certain climatological elements, and the RS element water is regarded as fundamental. We conducted a study of the monthly total rainfall, to long 60 years (1948/2007), collected from 31 meteorological stations (EMs) and distributed geographically in the state. In the interest of contributing to the local society to predict possible shortages, and / or development of public policies for the use of water resources in urban and rural areas. In order to obtain a model that can provide an approximation of the behavior of the average rainfall for each of the six homogeneous regions, as defined in the literature (Marques, 2005), held has an harmonic analysis of the data previously adjusted to 30-day months. Before the analisys, the properties were checked for normality, homogeneity of variance and stationarity. The data tested for normality and homogeneity of variances, have not passed satisfactory in these tests and, hence, there was a transformation of data, generating new data sets that met the conditions of homogeneity of variance and normality. The relative increase in the trend...

Medium term forecasting of rainfall using artificial neural networks

Iseri, Y.; Dandy, G.; Maier, H.; Kawamura, A.; Jinno, K.
Fonte: mssanz; http://mssanz.org.au/modsim05/authorsH-K.htm Publicador: mssanz; http://mssanz.org.au/modsim05/authorsH-K.htm
Tipo: Conference paper
Publicado em //2005 EN
Relevância na Pesquisa
26.72%
The state of the atmosphere and ocean can be characterized by climate indices. One of the well known indices is the Southern Oscillation Index (SOI). SOI measures the sea level pressure difference between Tahiti and Darwin, indicating the occurrence of the El Nià ±o phenomenon in the Central Pacific region. The Pacific Decadal Oscillation Index (PDOI) represents decadal scale atmosphere-ocean oscillation in the Pacific Ocean while the North Pacific Index (NPI) measures the intensity of the Aleutian low pressure cell ( Kawamura et al. 2003). A number of researchers have studied the possibility of forecasting rainfall several months in advance using climate indices such as SOI, PDOI and NPI (e.g. Silverman and Dracup, 2000). Furthermore, the existence of substantial databases of sea surface temperature anomalies (SST) opens the possibility of using these data to forecast rainfall several months in advance. Most of the research carried out in this area has used traditional statistical methods such as linear correlation or time series methods to identify the significant variables. These methods test for a linear relationship between the independent variables and rainfall, whereas the relationships are more likely to be non-linear as the underlying processes are themselves non-linear. This paper describes the use of partial mutual information (PMI) to identify the significant inputs for medium term rainfall forecasting in Japan. In particular...

Cascading Model Uncertainty From Medium Range Weather Forecasts (10 Days) Through a Rainfall-Runoff Model to Flood Inundation Predictions Within the European Flood Forecasting System (EFFS)

PAPPENBERGER Florian; BEVEN K.j.; HUNTER N.m.; BATES Paul; GOUWELEEUW Ben; THIELEN DEL POZO JUTTA; DE ROO ARIE
Fonte: European Geosciences Union Publicador: European Geosciences Union
Tipo: Articles in Journals Formato: Printed
ENG
Relevância na Pesquisa
26.69%
The political pressure on the scientific community to provide medium to long term flood forecasts has increased in the light of recentflooding events in Europe. Such demands can be met by a system consisting of three different model components (weather forecast, rainfall–runoff forecast and flood inundation forecast) which are all liable to considerable uncertainty in the input, output and model parameters.Thus, an understanding of cascaded uncertainties is a necessary requirement to provide robust predictions. In this paper, 10-day aheadrainfall forecasts, consisting of one deterministic, one control and 50 ensemble forecasts, are fed into a rainfall–runoff model (LisFlood) forwhich parameter uncertainty is represented by six different parameter sets identified through a Generalised Likelihood Uncertainty Estimation(GLUE) analysis and functional hydrograph classification. The runoff of these 52 * 6 realisations form the input to a flood inundation model(LisFlood-FP) which acknowledges uncertainty by utilising ten different sets of roughness coefficients identified using the same GLUEmethodology. Likelihood measures for each parameter set computed on historical data are used to give uncertain predictions of flow hydrographsas well as spatial inundation extent. This analysis demonstrates that a full uncertainty analysis of such an integrated system is limited mainlyby computer power as well as by how well the rainfall predictions represent potential future conditions. However...

Climate Resilient Ningbo Project : Local Resilience Action Plan, Volume 1. Final Report

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Economic & Sector Work :: Country Environmental Analysis (CEA); Economic & Sector Work
ENGLISH; EN_US
Relevância na Pesquisa
26.52%
Ningbo serves as the Chinese pilot city for the World Bank Climate Resilient Cities (CRC) Program. The CRC program aims to, prepare local governments in the East Asia region to better understand the concepts and consequences of climate change; how climate change consequences contribute to urban vulnerabilities; and what is being done by city governments in East Asia and around the world to actively engage in learning capacity building, and capital investment programs for building sustainable, resilient communities. This local resilience action plan (LRAP) had four parts. Part one investigated natural hazards weather observations and climate models. Seven key climatic parameters were selected: temperature, rainfall, drought, heat wave, flood, tropical cyclone, and sea level rise. Part two examined how the city functions, and pursues socio-economic development through a city vulnerability assessment. The qualitative, city vulnerability assessment was based on five sectors- people, infrastructure, environment...

Movimentos de massa gravitacionais - proposta de um sistema de previsão: aplicação na área urbana de Campos do Jordão - SP; Gravitational mass movements - proposal of a forecast system: application at the urban area of Campos do Jordão city - SP - Brazil

Ahrendt, Adriana
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/04/2005 PT
Relevância na Pesquisa
36.87%
O presente estudo consiste no desenvolvimento de um sistema de previsão de escorregamentos, baseado na quantificação da influência das chuvas transientes na estabilidade de encostas, por intermédio da identificação dos mecanismos de ruptura e dos processos físicos envolvidos na infiltração e distribuição da água no solo. O estudo foi realizado em parte da área urbana da cidade de Campos do Jordão-SP, estado de São Paulo, onde tem ocorrido de movimentos de massa gravitacionais é bastante comum. A metodologia empregada baseia-se no conhecimento das características gelógico-geotécnicas da área, acompanhada de trabalhos de campo e laboratoriais e da análise da relação entre a chuva e ocorrência dos movimentos de massa gravitacionais. Em uma primeira fase foram elaborados os documentos cartográficos básicos, como o mapa topográfico e carta de declividade, todos na escala 1:2.000. O trabalho de campo consistiu na identificação detalhada dos materiais inconsolidados e rochas, bem como na caracterização das feições de movimentos de massa gravitacionais já existentes na área, e elaboração do mapa de localização das feições. Paralelamente, foram obtidas amostras deformadas e indeformadas e realizados ensaios em laboratório. Este procedimento permitiu identificar oito diferentes classes de materiais inconsolidados distribuídos em dez unidades e...

Rainfall Mechanisms for the Dominant Rainfall Mode over Zimbabwe Relative to ENSO and/or IODZM

Manatsa, Desmond; Mukwada, Geoffrey
Fonte: The Scientific World Journal Publicador: The Scientific World Journal
Tipo: Artigo de Revista Científica
Publicado em 03/05/2012 EN
Relevância na Pesquisa
36.49%
Zimbabwe's homogeneous precipitation regions are investigated by means of principal component analysis (PCA) with regard to the underlying processes related to ENSO and/or Indian Ocean Dipole zonal mode (IODZM). Station standardized precipitation index rather than direct rainfall values represent the data matrix used in the PCA. The results indicate that the country's rainfall is highly homogeneous and is dominantly described by the first principal mode (PC1). This leading PC can be used to represent the major rainfall patterns affecting the country, both spatially and temporarily. The current practice of subdividing the country into the two seasonal rainfall forecast zones becomes irrelevant. Partial correlation analysis shows that PC1 is linked more to the IODZM than to the traditional ENSO which predominantly demonstrates insignificant association with PC1. The pure IODZM composite is linked to the most intense rainfall suppression mechanisms, while the pure El Niño composite is linked to rainfall enhancing mechanisms.

Multivariate forecast of winter monsoon rainfall in India using SST anomaly as a predictor: Neurocomputing and statistical approaches

Chattopadhyay, Goutami; Chattopadhyay, Surajit; Jain, Rajni
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/10/2009
Relevância na Pesquisa
26.58%
In this paper, the complexities in the relationship between rainfall and sea surface temperature (SST) anomalies during the winter monsoon (November-January) over India were evaluated statistically using scatter plot matrices and autocorrelation functions.Linear as well as polynomial trend equations were obtained and it was observed that the coefficient of determination for the linear trend was very low and it remained low even when polynomial trend of degree six was used. An exponential regression equation and an artificial neural network with extensive variable selection were generated to forecast the average winter monsoon rainfall of a given year using the rainfall amounts and the sea surface temperature anomalies in the winter monsoon months of the previous year as predictors. The regression coefficients for the multiple exponential regression equation were generated using Levenberg-Marquardt algorithm. The artificial neural network was generated in the form of a multiplayer perceptron with sigmoid non-linearity and genetic-algorithm based variable selection. Both of the predictive models were judged statistically using the Willmott index, percentage error of prediction, and prediction yields. The statistical assessment revealed the potential of artificial neural network over exponential regression.; Comment: 18 pages

Spatial--temporal mesoscale modeling of rainfall intensity using gage and radar data

Fuentes, Montserrat; Reich, Brian; Lee, Gyuwon
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/01/2009
Relevância na Pesquisa
26.74%
Gridded estimated rainfall intensity values at very high spatial and temporal resolution levels are needed as main inputs for weather prediction models to obtain accurate precipitation forecasts, and to verify the performance of precipitation forecast models. These gridded rainfall fields are also the main driver for hydrological models that forecast flash floods, and they are essential for disaster prediction associated with heavy rain. Rainfall information can be obtained from rain gages that provide relatively accurate estimates of the actual rainfall values at point-referenced locations, but they do not characterize well enough the spatial and temporal structure of the rainfall fields. Doppler radar data offer better spatial and temporal coverage, but Doppler radar measures effective radar reflectivity ($Ze$) rather than rainfall rate ($R$). Thus, rainfall estimates from radar data suffer from various uncertainties due to their measuring principle and the conversion from $Ze$ to $R$. We introduce a framework to combine radar reflectivity and gage data, by writing the different sources of rainfall information in terms of an underlying unobservable spatial temporal process with the true rainfall values. We use spatial logistic regression to model the probability of rain for both sources of data in terms of the latent true rainfall process. We characterize the different sources of bias and error in the gage and radar data and we estimate the true rainfall intensity with its posterior predictive distribution...

Ensemble spread and systematic errors in the medium-range predictions during the Indian summer monsoon

KAR,S. C.; IYENGAR,G. R.; BOHRA,A. K.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
Relevância na Pesquisa
26.82%
For preparing medium range weather forecasts, two global coarse resolution models at different resolutions were used at the National Centre for Medium Range Weather Forecasting (NCMRWF), India. In order to improve the forecasting skill, an ensemble prediction system (EPS) was implemented on experimental basis. For generating initial perturbations a breeding method was implemented. Experimental forecast runs with 8-member ensemble were carried out and results are analyzed for a monsoon season. The ensemble mean of rainfall forecasts shows that over the broad region of Gangetic Plains, the EPS brings out the monsoon activity (active and weak spell) reasonably well six days in advance. However, over the eastern parts of India, the ensemble mean rainfall is good only in short-range. The ensemble spread becomes quite large from about day-4 forecast and beyond. An examination of the rainfall pattern from day-1 to day-6 forecasts by the model and the ensemble spread shows there is no linearity in the increase of spread with the rainfall amount. The model has a systematic tendency to enhance rainfall activity over the central Bay of Bengal and eastern parts of India as the length of forecast is increased. At the same time, the model tends to dry up over the equatorial Indian Ocean region...

Multi-model ensemble forecasting of rainfall over Indian monsoon region

ROY BHOWMIK,S. K; DURAI,V. R
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2008 EN
Relevância na Pesquisa
36.42%
In the present study, a method is proposed for the ensemble forecasting of rainfall over the Indian monsoon region based on daily outputs of four operational numerical weather prediction (NWP) models in the short-range time scale (up to 48 hours). The method is applied to prepare 24 and 48 hours ensemble forecastings of rainfall in the test mode daily during the summer monsoon 2006, using the rainfall prediction of constituent models with the pre-assigned grid point weights. The prediction skill of the ensemble forecasts is examined against observations and corresponding outputs of each constituent model. The intercomparison reveals that the method is capable to improve the forecast by taking the strength of each constituent model. The method has the potential for operational application.

A statistical study of seasonal winter rainfall prediction in the Comahue region (Argentina)

GONZÁLEZ,M. H.; SKANSI,M. M.; LOSANO,F.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
26.49%
The aim of this study is to detect the possible causes of the May-to-July rainfall (MJJ) over the Limay and Neuquén river basins. In order to establish the existence of previous circulation patterns associated with interannual rainfall variability, the mean areal precipitation in each one of the basins was correlated to some predictors during the previous three month period (February-March-April). The result is that MJJ rainfall in both basins is related to sea surface temperature and geopotential heights at different levels previously observed in some specific areas of Indian and Pacific Oceans, probably due to wave trains which begin in those areas and then displace towards the Argentine Patagonia coast, thus generating precipitation systems. There are also observed significant correlations with sea surface temperature in the Atlantic Ocean over Brazil and the Argentine coast, associated with the water vapor income into the continent and with zonal and meridional wind over the basins, related to humid air advection. The prediction schemes, using multiple linear regressions, showed that the selected variables are the cause of the 51% of the MJJ rainfall variance in the Limay river basin and the 44% in the Neuquén river one. The scheme was validated by using a cross-validation method and significant correlations were detected between observed and forecast rainfall. The 2009 winter rainfall was analyzed and showed that circulation indicators were useful to predict winter rainfall.

An approach to seasonal forecasting of summer rainfall in Buenos Aires, Argentina

GONZÁLEZ,M. H.; CARIAGA,M. L.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2009 EN
Relevância na Pesquisa
36.81%
This paper analyzes some summer rainfall characteristics in Buenos Aires and developes a seasonal prediction scheme. Buenos Aires is located along the coast of the Río de la Plata in Argentina. The outstanding rainfall feature is the presence of an annual cycle with maximum precipitation in summer. The analysis of the annual rainfall evolution since 1908 showed a positive trend of 2.1 mm/year and 1.8 mm/year for the period between December and February, representative of the summer season. The Observatorio Central Buenos Aires/station, located in the downtown, registered a mean annual accumulated rainfall of 1070 mm with a standard deviation of 239 mm, during the period 1908-2007. The mean accumulated precipitation during January, February and March was 305 mm with a standard deviation of 125 mm. The wet and dry periods were identified and the dry periods tended to be longer during 1908-1957 meanwhile wet periods resulted longer and more intense in 1958-2007. Accumulated rainfall between December and February was related to some mean meteorological variables between September and November, with the aim to develop a statistical prediction scheme. Careful selection of predictors, based largely on physical reasoning, was done and they were used in a regression model...

Development of a framework for an integrated time-varying agrohydrological forecast system for Southern Africa: Initial results for seasonal forecasts

Ghile,YB; Schulze,RE
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
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Uncertainty about hydro-climatic conditions in the immediate future (today), as well as the near (up to one week) and more distant futures (up to one season) remains a fundamental problem challenging decision makers in the fields such as water resources, agriculture, and many other water-sensitive sectors in Southern Africa. Currently many institutions, such as the SA Weather Service, provide weather and climate forecasts with lead times ranging from 1 d to one season. However, disconnects exist between the weather/climate forecasts and their links to agrohydrological models, and in the applications of forecast information for targeted agricultural and water-related decision-making. The skills level of the current weather and climate forecasts, and the mismatch in scales between the output from weather/climate models and the spatial scales at which hydrological models are applied, as well as the format of seasonal forecasts in that they cannot be used directly in agrohydrological models, are some of the problems identified in this study and are being addressed. This has necessitated the development of a GIS-based framework in which the 'translation' of weather and climate forecasts into more tangible agrohydrological forecasts such as streamflows...