EVALUATION OF MULTI-SATELLITE PRECIPITATION VIS-À-VIS TERRESTRIAL MEASUREMENT

Abstract

Rainfall is very dynamic in nature, constantly varying in magnitude and intensity as it passes over an area. Traditionally, Rain gauges are used for measurement of rainfall at ground stations. Nowadays, various near real time satellite based rainfall products are available The sensors of these satellite measure the reflection of microwave and near infrared waves from the falling drops of rain over a volume. Basically, these products are derived and calibrated locally by using many algorithms and then corresponding precipitation is established so there are chances of errors and biases in these products. NASA and JAXA, with the Tropical Rainfall Measure Mission (TRMM) space borne precipitation sensor had developed a multi-satellite precipitation product TRMM3B42_V7 to estimate the spatial and temporal distribution of precipitation in near real time. The applications of precipitation product TRMM3B42_V7 require a comprehensive evaluation and validation prior to employing suitable bias correction techniques. This study will provide information about the ability and accuracy of the TRMM to retrieve daily and monthly precipitation in comparison with the rain gauge precipitation data of 6 meteorological stations over Aurangabad district of Maharashtra, India. To carry out this comparison, a synthesis of eleven years of precipitation data, from 2003 to 2013, is used, evaluated, validated and compared. Further, the bias correction techniques are applied to TRMM3B42_V7 precipitation dataset by resemble with the terrestrial rain gauge data. The validation and inter comparison of multi-satellite precipitation versus rain gauge precipitation is accomplished using statistical indices and 2x2 contingency table parameters. For bias correction, cumulative distribution functions are plotted and mapping is done. As a result of bias correction, the errors and biases are minimized and accuracy is enhanced. In conclusion, the TRMM overestimated the actual rain gauge measurements in both daily and monthly temporal resolution. The relevance of the comparative analysis is to analyze the TRMM precipitation product datasets are reliable and an alternative to the rain gauge precipitation in ungauged basins. Future scope of the work is to evaluate and validate the Global Precipitation Mission (GPM) products which are a successor of TRMM, against the rain gauge measurements.