scholarly journals On the Importance of Gauge-Undercatch Correction Factors and Their Impacts on the Global Precipitation Estimates

2021 ◽  
Author(s):  
Mohammad Reza Ehsani ◽  
Ali Behrangi
Keyword(s):  
Surface Air Temperature ◽  
Global Precipitation Climatology Project ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Correction Factors ◽  
Dynamic Correction ◽  
Near Surface ◽  
Annual Variations ◽  
Precipitation Climatology ◽  
Global Precipitation

Precipitation gauges are critical for measuring precipitation rates at regional and global scales and are often used to calibrate precipitation rates estimated from other instruments such as satellites. However, precipitation measured at the gauges is affected by gauge-undercatch that is often larger for solid precipitation. In the present work, two popular gauge-undercatch correction factors are assessed: one utilizes a dynamic correction model and is used in the Global Precipitation Climatology Centre (GPCC) Monitoring product and the other one employs a fixed climatology and is used in the Global Precipitation Climatology Project (GPCP) product. How much the choice of correction factors can impact the total estimate of precipitation was quantified over land at seasonal, annual, regional, and global scales. The correction factors are also compared as a function of the environmental variables used in their development, among those are near-surface air temperature, relative humidity, wind speed, elevation, and precipitation intensity. Results show that correction factors can increase the annual precipitation rate based on the gauges by ~9.5 % over the global land (excluding Antarctica), although this amount can vary from ~6.3% (in boreal summer) to more than 10% (in boreal winter), depending on the season and the method used for gauge-undercatch correction. Annual variations of correction factors can also be large, so the use of the fixed climatology correction factors requires caution. Given their magnitudes and differences, selection of appropriate correction factors can have important implications in refining the water and energy budget calculations.

scholarly journals Using GRACE to Estitmate Snowfall Accumulation and Assess Gauge Undercatch Corrections in High Latitudes

2018 ◽  
Vol 31 (21) ◽  
pp. 8689-8704 ◽  
Author(s):  
Ali Behrangi ◽  
Alex Gardner ◽  
John T. Reager ◽  
Joshua B. Fisher ◽  
Daqing Yang ◽  
...  
Keyword(s):  
High Latitude ◽  
Surface Air Temperature ◽  
Global Precipitation Climatology Project ◽  
Dynamic Correction ◽  
Northern Asia ◽  
Near Surface ◽  
Precipitation Climatology ◽  
Global Precipitation Climatology Centre ◽  
Terrestrial Water ◽  
Global Precipitation

Ten years of terrestrial water storage anomalies from the Gravity Recovery and Climate Experiment (GRACE) were used to estimate high-latitude snowfall accumulation using a mass balance approach. The estimates were used to assess two common gauge-undercatch correction factors (CFs): the Legates climatology (CF-L) utilized in the Global Precipitation Climatology Project (GPCP) and the Fuchs dynamic correction model (CF-F) used in the Global Precipitation Climatology Centre (GPCC) monitoring product. The two CFs can be different by more than 50%. CF-L tended to exceed CF-F over northern Asia and Eurasia, while the opposite was observed over North America. Estimates of snowfall from GPCP, GPCC-L (GPCC corrected by CF-L), and GPCC-F (GPCC corrected by CF-F) were 62%, 64%, and 46% more than GPCC over northern Asia and Eurasia. The GRACE-based estimate (49% more than GPCC) was the closest to GPCC-F. We found that as near-surface air temperature decreased, the products increasingly underestimated the GRACE-based snowfall accumulation. Overall, GRACE showed that CFs are effective in improving GPCC estimates. Furthermore, our case studies and overall statistics suggest that CF-F is likely more effective than CF-L in most of the high-latitude regions studied here. GPCP showed generally better skill than GPCC-L, which might be related to the use of satellite data or additional quality controls on gauge inputs to GPCP. This study suggests that GPCP can be improved if it employs CF-L instead of CF-F to correct for gauge undercatch. However, this implementation requires further studies, region-specific analysis, and operational considerations.

The Global Precipitation Climatology Project

2007 ◽  
pp. 25-35 ◽  
Author(s):  
Arnold Gruber ◽  
Bruno Rudolf ◽  
Mark M. Morrissey ◽  
Toshiyuki Kurino ◽  
John E. Janowiak ◽  
...  
Keyword(s):  
Global Precipitation Climatology Project ◽  
Precipitation Climatology ◽  
Global Precipitation

scholarly journals The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

1997 ◽  
Vol 78 (1) ◽  
pp. 5-20 ◽  
Author(s):  
George J. Huffman ◽  
Robert F. Adler ◽  
Philip Arkin ◽  
Alfred Chang ◽  
Ralph Ferraro ◽  
...  
Keyword(s):  
Global Precipitation Climatology Project ◽  
Precipitation Climatology ◽  
Global Precipitation

scholarly journals Prediction of Dry-Season Precipitation in Tropical West Africa and Its Relation to Forcing from the Extratropics

2009 ◽  
Vol 24 (4) ◽  
pp. 1064-1084 ◽  
Author(s):  
Peter Knippertz ◽  
Andreas H. Fink
Keyword(s):  
West Africa ◽  
Local Population ◽  
Temporal Correlation ◽  
Global Precipitation Climatology Project ◽  
Precipitation Anomaly ◽  
Dry Season ◽  
Precipitation Event ◽  
Boreal Winter ◽  
False Alarms ◽  
Global Precipitation

Abstract Precipitation during the boreal winter dry season in tropical West Africa is rare but occasionally results in significant impacts on the local population. The dynamics and predictability of this phenomenon have been studied very little. Here, a statistical evaluation of the climatology, dynamics, and predictions of dry-season wet events is presented for the region 7.5°–15°N, 10°W–10°E. The analysis is based upon Global Precipitation Climatology Project (GPCP) merged satellite–gauge pentad rainfall estimates and 5-day 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) precipitation forecasts, and covers the 23 dry seasons (November–February) during 1979/80–2001/02. Wet events are defined as pentads with an area-averaged precipitation anomaly of more than +200% with respect to the mean seasonal cycle. Composites of the 43 identified events indicate an association with a trough over northwestern Africa, a tropical plume on its eastern side, unusual precipitation at the northern and western fringes of the Sahara, and reduced surface pressure over the Sahara, which allows an inflow of moist southerlies from the Gulf of Guinea to feed the unusual dry-season rainfalls. The results give evidence for a preconditioning by another disturbance about 1 week prior to the precipitation event. The ERA-40 forecasts show a high temporal correlation with observations, a general wet bias, but a somewhat too low number of wet events. With 53% of all identified events correctly forecasted and only 32% of forecasted events not verified, the model shows moderate skill in contrast to the prediction of many other tropical precipitation systems. A separate consideration of hits, misses, and false alarms corroborates the previously proposed hypothesis that a strong extratropical influence enhances the quality of predictions in this region. The results should encourage weather services in West Africa to take advantage of available dry-season precipitation forecasts in terms of the dissemination of early warnings.

scholarly journals Spatial and Temporal Variation of Precipitation in Greece and Surrounding Regions Based on Global Precipitation Climatology Project Data

2008 ◽  
Vol 21 (6) ◽  
pp. 1349-1370 ◽  
Author(s):  
N. Hatzianastassiou ◽  
B. Katsoulis ◽  
J. Pnevmatikos ◽  
V. Antakis
Keyword(s):  
Large Scale ◽  
Precipitation Amount ◽  
Global Precipitation Climatology Project ◽  
Spatial And Temporal Variation ◽  
Mean Annual Precipitation ◽  
Study Region ◽  
Precipitation Climatology ◽  
Spatial Coverage ◽  
Precipitation Decrease ◽  
Global Precipitation

Abstract In this study, the spatial and temporal distribution of precipitation in the broader Greek area is investigated for the 26-yr period 1979–2004 by using monthly mean satellite-based data, with complete spatial coverage, taken from the Global Precipitation Climatology Project (GPCP). The results show that there exists a clear contrast between the more rainy western Greek area (rainside) and the drier eastern one (rainshadow), whereas there is little precipitation over the islands, particularly in the southern parts. The computed long-term areal mean annual precipitation amount averaged for the study area is equal to P = 639.8 ± 44.8 mm yr−1, showing a decreasing trend of −2.32 mm yr−1 or −60.3 mm over the 26-yr study period, which corresponds to −9.4%. This decrease of precipitation, arising primarily in winter and secondarily in spring, is the result of a decreasing trend from 1979 through the 1980s, against an increase during the 1990s through the early 2000s, followed again by a decrease up to the year 2004. The performed analysis reveals an increasing trend of precipitation in the central and northern parts of the study region, contrary to an identified decreasing trend in the southern parts, which is indicative of threatening desertification processes in those areas in the context of climatic changes in the climatically sensitive Mediterranean basin. In addition, the analysis shows that the precipitation decrease is due to a corresponding decrease of maximum precipitation against rather unchanged minimum precipitation amounts. The analysis indicates that the changing precipitation patterns in the region during winter are significantly anticorrelated with the North Atlantic Oscillation (NAO) index values, against a positive correlation during summer, highlighting thus the role of large-scale circulation patterns for regional climates. The GPCP precipitation data are satisfactorily correlated with instrumental measurements from 36 stations uniformly distributed over the study area (correlation coefficient R = 0.74 for all stations; R = 0.63–0.91 for individual stations).

scholarly journals Estimating Climatological Bias Errors for the Global Precipitation Climatology Project (GPCP)

2012 ◽  
Vol 51 (1) ◽  
pp. 84-99 ◽  
Author(s):  
Robert F. Adler ◽  
Guojun Gu ◽  
George J. Huffman
Keyword(s):  
Error Estimate ◽  
Error Estimates ◽  
Relative Error ◽  
Absolute Magnitude ◽  
Global Precipitation Climatology Project ◽  
Bias Error ◽  
Precipitation Climatology ◽  
The Mean ◽  
The Tropics ◽  
Global Precipitation

AbstractA procedure is described to estimate bias errors for mean precipitation by using multiple estimates from different algorithms, satellite sources, and merged products. The Global Precipitation Climatology Project (GPCP) monthly product is used as a base precipitation estimate, with other input products included when they are within ±50% of the GPCP estimates on a zonal-mean basis (ocean and land separately). The standard deviation σ of the included products is then taken to be the estimated systematic, or bias, error. The results allow one to examine monthly climatologies and the annual climatology, producing maps of estimated bias errors, zonal-mean errors, and estimated errors over large areas such as ocean and land for both the tropics and the globe. For ocean areas, where there is the largest question as to absolute magnitude of precipitation, the analysis shows spatial variations in the estimated bias errors, indicating areas where one should have more or less confidence in the mean precipitation estimates. In the tropics, relative bias error estimates (σ/μ, where μ is the mean precipitation) over the eastern Pacific Ocean are as large as 20%, as compared with 10%–15% in the western Pacific part of the ITCZ. An examination of latitudinal differences over ocean clearly shows an increase in estimated bias error at higher latitudes, reaching up to 50%. Over land, the error estimates also locate regions of potential problems in the tropics and larger cold-season errors at high latitudes that are due to snow. An empirical technique to area average the gridded errors (σ) is described that allows one to make error estimates for arbitrary areas and for the tropics and the globe (land and ocean separately, and combined). Over the tropics this calculation leads to a relative error estimate for tropical land and ocean combined of 7%, which is considered to be an upper bound because of the lack of sign-of-the-error canceling when integrating over different areas with a different number of input products. For the globe the calculated relative error estimate from this study is about 9%, which is also probably a slight overestimate. These tropical and global estimated bias errors provide one estimate of the current state of knowledge of the planet’s mean precipitation.

scholarly journals Comparação dos dados de precipitação gerados Pelo gpcp vs observados para o estado do rio grande do sul

2015 ◽  
Vol 30 (4) ◽  
pp. 415-422 ◽  
Author(s):  
Claudinéia Brazil Saldanha ◽  
Bernadete Radin ◽  
Maria Angélica Gonçalves Cardoso ◽  
Matheus Lara Rippel ◽  
Ludmila Losada da Fonseca ◽  
...  
Keyword(s):  
Rio Grande ◽  
Global Precipitation Climatology Project ◽  
Rio Grande Do Sul ◽  
Precipitation Climatology ◽  
Global Precipitation

RESUMO Fontes alternativas de dados de precipitação têm se tornado cada vez mais usuais, possibilitando também uma avaliação de áreas com ausência de série longa e/ou continua de dados meteorológicos ou com baixa densidade de estações meteorológicas. O objetivo deste trabalho foi avaliar o desempenho das séries de dados do Global Precipitation Climatology Project (GPCP) para o Estado do Rio Grande do Sul e verificar a sua possível utilização na ausência de dados observados de precipitação. Nesse trabalho utilizaram-se séries mensais de precipitação do GPCP fornecidas pela National Oceanic and Atmospheric Administration (NOAA) com uma resolução de 0,5° x 0,5° latitude-longitude, para o período de 1979 a 2010. As análises foram realizadas a partir da comparação com dados de precipitação de 22 estações meteorológicas localizadas no estado do Rio Grande do Sul. A partir dos resultados das análises estatísticas, observa-se que o GPCP apresentou um bom desempenho na região de estudo, com o coeficiente de correlação em torno de 0,81. Com isso, infere-se que os dados do GPCP podem ser utilizados como fonte alternativa de dados de precipitação, quando as séries temporais possuem períodos de falhas.

scholarly journals PLANETARY-SCALE CLIMATIC INDICES AND RELATIONSHIP BETWEEN DECADAL VARIABILITY OF RAINFALL IN NORTHEASTERN AND SOUTHERN BRAZIL

2013 ◽  
Vol 31 (1) ◽  
pp. 31 ◽  
Author(s):  
Luciana Figueiredo Prado ◽  
Ilana Wainer
Keyword(s):  
Decadal Variability ◽  
Southern Oscillation ◽  
Global Precipitation Climatology Project ◽  
Tropical Atlantic ◽  
Climatic Index ◽  
Climatic Indices ◽  
Atmospheric Research ◽  
Precipitation Climatology ◽  
Environmental Prediction ◽  
Global Precipitation

This work analyzes the relationship between climatic index and rainfall in the Northeastern (NE) and Southern (S) Brazil, in decadal timescale. The climatic indices were obtained from the reanalysis data from NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) between 1948 and 2008. Subsequently, (indices and rainfall correlation coefficients derived from the GPCP (Global Precipitation Climatology Project) dataset were calculated using filtered and non-filtered time series, within the decadal frequency). The results show that ElNi ˜no Southern Oscillation (ENSO) is the main phenomenon influencing NE rainfall due to related changes in tropical circulation while the Intertropical Convergence Zone (ITCZ) annual cycle also affects rainfall in the NE to a lesser extent. Meanwhile, in the Southern region, the most important phenomenon is the Southern Annular Mode (SAM) which controls cyclones activity in mid-latitudes. The Tropical Atlantic dipole index (ADI) also influences the rainfall in the Southern, and this might be related to moisture being transported from the ocean to the continent, which is then carried to the South by the Low Level Jet. It is also suggested that the decadal variability of the Tropical Atlantic Ocean and its influence on the precipitation in NE andS regions of Brazil are episodic because no significant correlations were obtained at decadal frequency. Finally, the spectral analysis revealed that the interannual timescale is the main frequency of variability in both studied regions, affecting differently each one of them. RESUMO: Este trabalho analisa as relações entre índices climáticos e a precipitação no Nordeste (NE) e Sul (S) do Brasil, em escala decadal. Os índices climáticos foram obtidos a partir de dados da reanálise do NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research), para o período de 1948 a 2008. Posteriormente, foram obtidos os coeficientes de correlação entre os índices e as anomalias de precipitação advindas do banco de dados do GPCP (Global Precipitation Climatology Project) nestas regiões, utilizando séries não filtradas e séries filtradas na frequência decadal. Os resultados sugerem que o principal fenômeno que modula a precipitação no NE é o El Ni˜no-Oscilação Sul (ENOS), devido às alterações na circulação tropical, e também o ciclo anual da Zona de Convergência Intertropical (ZCIT), que modula a estação chuvosa do NE. Na região S, o fenômeno que mais influencia a precipitação em escala decadal é o Modo Anular Sul (SAM),por modular a atividade ciclogenética em latitudes médias, além do índice do dipolo do Atlântico Tropical (DA), que pode estar ligado ao aporte de umidade oceânica para o continente, e levada ao S pelo jato de baixos níveis. Também se sugere que a variabilidade decadal do Atlântico tropical e sua influência na precipitação no NE sejam episódicas, e não periódica, já que não foram obtidas correlações importantes para este índice, na frequência estudada. Finalmente, a análise espectral revelouque a escala interanual é a principal frequência de variabilidade temporal em ambas as regiões, com efeitos diversos em cada uma delas.Palavras-chave: precipitação, ENOS, Atlântico, SAM. 

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