EVALUATIONOF SATELLITE DERIVED RAINFALL DATA FOR MT KENYA REGION

Abstract

Rainfall  information  is  crucial more  so for an  economy  that  heavily  relies on  rain  fed  agriculture like  Kenya. However, the spatial distribution of rain gauges is low and is only representative of location of measurement. Satellite based precipitation products can be used to supplement the data acquired from the ground stations available.  There  is  need  of  validation  of  the  satellite  products  by  establishing  a  level  of  confidence  and subsequently  the  probability  of  use  of  the data  in  areas  where  ground  observations  are  not  available.  The performance of RFE V2 and GPCP 1DD was evaluated against observations for the region around Mt. Kenya. The aim  was  to  determine  the  level  of  correlation  between  the  satellite-based  precipitation  and  the  ground observations. Based on the analysis, resolve on the use of the data in cases where ground observations are not available. Observation data from six ground stations for the period between 2001 and 2012 were used in the analysis.  Over  estimation  or  underestimation  was  initially  calculated.  Weights  were  assigned  based  on  their range  of  deviation  from  the  observations.  The  coefficient  of  determination  was  also  computed  and  weights assigned  based  on  their  precision  to  the  observed  values.  Weights  from  the  two  parameters  were  then multiplied to give a combined goodness of fit. RFE performed better in most of the stations. An analysis of the performance of the satellite estimates should be done using daily observation data as opposed to the monthly data used. 

Key words: Climate change, weather forecasting, precipitation, GPCP, RFE