Evaluation of global precipitation data sets over the Iberian Peninsula

Abstract

[1] A new publicly available daily gridded precipitation data set over mainland Portugal is presented. This data set is also combined with a recent Spanish data set to obtain a high resolution (0.2°× 0.2°) Iberian data set, labeled IB02. This data set covers the period from 1950 to 2003 and is based on a dense network, with more than 2000 and 400 quality-controlled stations over Spain and Portugal, respectively. The ordinary kriging method, applied over Portugal for consistency with the Spanish data set, performs slightly better than simpler interpolation techniques tested over Portugal. Additionally, this paper evaluates four global gridded data sets: two based on rain gauges (Climate Research Unit (CRU) and Global Precipitation Climate Center (GPCC)) and two European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA-40 and ERA-Interim), comparing them with the IB02 data set. The main features of the spatial distribution of IB02 mean annual precipitation are reasonably captured by the global data sets, despite their dry biases, mostly in mountainous regions. The four data sets perform better in western Iberia and are able to identify the major drought spells at the Iberian scale. Despite these similarities, GPCC outperforms CRU and ERA-Interim is superior to ERA-40 with respect to several aspects, such as annual cycle and drought detection. The performance of CRU is similar to that of ERA-Interim. The frequency of wet days is overestimated by reanalyses, mainly by ERA-Interim, while heavy precipitation events are underestimated, mostly by ERA-40. At 5 day scales, ECMWF reanalyses reveal difficulties in predicting the magnitude of precipitation, despite their greater ability to estimate the peak locations.Citation: Belo-Pereira, M., E. Dutra, and P. Viterbo (2011), Evaluation of global precipitation data sets over the Iberian Peninsula,

Circulation weather types and spatial variability of daily precipitation in the Iberian Peninsula

“…Therefore, the use of a daily dataset, even with a smaller total number of stations, could represent an advantage to the analysis. This goal has become feasible only recently due to the merging of Spanish and Portuguese (Belo-Pereira et al, 2011), into the high density daily gridded precipitation data set "Iberia02." To a certain extent, this work provides the extension of the previous studies by the authors Cortesi et al (2013a,b), with several major changes; on the one hand, unlike the monthly regression model widely used in Cortesi et al (2013a), the analysis in this work was performed using the daily gridded "Iberia02" precipitation dataset.…”

“…It is based on a dense network of rain gauges, combining two national data sets, "Spain02" for peninsular Spain and Balearic islands , and "PT02" for mainland Portugal (Belo-Pereira et al, 2011), with a total of more than 2000 station over Spain and four hundred stations over Portugal, all quality-controlled and homogenized. Although the actual number of stations in any given year varies substantially due to variable availability of stations.…”

“…The Portuguese dataset is based on a total of 806 station, most of which (726) have at least 10 years of data. Although several interpolation methods were tested to build the Portuguese gridded dataset (Belo-Pereira et al, 2011), the final choice was the same ordinary Kriging employed for the Spanish data .…”

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

“…Kidd et al (2013) found that precipitation in the tropical Atlantic is skewed to the east towards the African coast by ERA-Interim. On the other hand, several studies have shown that in the area of the Iberian Peninsula (Belo-Pereira et al, 2011) or in the area of four African river basins (Thiemig et al, 2012), ERA-Interim overestimates the frequency of rain events as well.…”

WRFhigh resolution simulation of Iberian mean and extreme precipitation climate

“…Herrera et al (2010aHerrera et al ( , 2010b used an extensive compilation of about 2000 daily observations in Spain to build a new daily gridded dataset, at 0.2 • × 0.2 • of horizontal resolution (latitude-longitude), for the period 1950 to March 2008. Belo-Pereira et al (2011) compiled around 400 stations and used the similar technical specifications to extend the dataset into Portugal. The merged dataset contains daily precipitation for the whole Iberian Peninsula, from 1950 to 2003, based on a dense network of rain gauges, of about 2400.…”