Having long-term precipitation data is fundamental to reliable
drought monitoring. The GPCP, with global coverage and
long-term monthly data, has been widely used in weather and
climate change studies. However, the data is not available
in near real-time due to post-processing needed to combine
all satellite and rain gauge data sets. This issue limits the
application of long-term satellite data to real-time drought
monitoring. In this study, as schematically shown in figure 1,
the long-term GPCP satellite data is merged with real-time
satellite estimates (here, TMPA-RT and PERSIANN) for
drought analysis using a Bayesian-based correction algorithm.
In the merged data set, the climatology is driven by
GPCP data, whereas the near past data (approximately 9–18
months) are based on real-time satellite precipitation data
(typically available to public within few hours to days after
observation).