Bias correction of global daily rain gauge measurements

Abstract

Up to the present global precipitation climatologies based on rain gauges have been corrected for systematic measurement errors using monthly correction factors only. We present results from a statistical correction model for daily measurements. It was developed in the framework of BALTEX and adapted for the Global Precipitation Climatology Centre (GPCC) to correct global daily rain gauge data routinely transmitted via GTS. We focus on regions of the GEWEX continental scale experiments BALTEX (Europe), GAME (Asia), LBA (South-America) and GCIP (North- America). The correction model was applied to 2 years of data (1996, 1997) and compared with the correction factors of the widely used precipitation climatology of Legates (1987). In the BALTEX region our averaged daily correction factor is about equal to the monthly correction given by Legates during the summer months, while Legates estimated higher corrections for snow (up to 50 %). In the regions of GAME and LBA the corrections given by Legates are also generally higher (50 – 100 %) than our corrections. This is opposite to the corrections calculated for GCIP rain gauges, which are not significantly different.