Attempt to detect maintenance need rain gauge station by double-mass analysis

Currently, 112 Automatic Weather Stations (AWS) and over 1,000 Automatic Rain Gauges (ARG), approximately 2,000 AWS in total including stations outside the national hydrometeorological network are installed in the nationwide country of Vietnam so that they can be used for Quantitative Precipitation Estimation of weather radars, etc. Meanwhile, it takes a vast amount of time and cost to properly operate and maintain the large number of AWS. Besides, rain gauges cannot be checked whether it has properly operated without a certain amount of rain. This research attempted to detect maintenance- need rain gauges of the AWS by the slope and R² values obtained by double- mass analysis against the distance between the stations. Evaluated distances were used for the classification of AWS. As “Class 1 AWS” is the distance within 5 km and “Class 2 AWS” is the distance within 20 km and the criteria were obtained by AMeDAS data of the Japan Meteorological Agency. Additionally, the process is cycled several times to expand the candidate AWS. The result says that stations except 125 Class 1 AWSs and 710 Class 2 AWSs need to be checked. It is suggested that this assessment can be used to detect maintenance need stations; however, periodical maintenance is still needed for proper observation because this assessment also needs reliable AWSs.