M-2 : Processing of precipitation data

Abstract

Preliminary processing of the precipitation data is essential before it is put to further use in analysis. Processing of precipitation data has two major objectives. One is to evaluate the data for its accuracy and the other is to prepare the data in a form appropriate for subsequent analysis and other applications. While some errors are observational or instrumental, others occur while recording, transmitting and storing the data. With the volume of precipitation data ' to be handled increasing, manual quality control would be impossible and the advent of high speed digital computers has made possible computerised processing of precipitation data.

Precipitation data processing could be conceived of as a system through which the basic (raw) data could be transferred into freely accessible and readily usable form. Essentially, the system would consist of a number of manual and computerised processing procedures which include besides data collection,

i) preliminary processing,

ii) storage of data on computer compatible devices,

iii) quality control,

iv) editing,

v) data conversion

vi) further analysis and

vii) storage of analysed data into computer disc files

The system developed by users of precipitation data for its processing has to be adaptable both for climatological analysis as well as operation in real time. It has to be flexible enough to handle data from future precipitation data collection sources such as Radar and Satellites.

In this manual appropriate procedures for carrying out the various components of the processing system are described keeping in view the precipitation data collection and storage in India. Where necessary, the procedures are explained with examples. Two computer programmes, one for identifying missing data in daily rainfall data and the other for distribution of daily rainfall into hourly rainfall and computing the average hourly catchment rainfall are also provided.