This document was last updated on June 18, 2012. Copy Right: Indian Institute of Tropical Meteorology (IITM) Homi Bhabha Road Pune 411 008, India The accompanying data as described below may be freely used and redistributed for non-profit and non-commercial research purposes, provided IITM is duly acknowledged as the data source. Any redistribution should necessarily include this document. Title: IITM Indian regional/subdivisional Monthly Rainfall data set (IITM-IMR) Contributors: D.A. Mooley B. Parthasarathy K. Rupa Kumar N.A. Sontakke A.A. Munot D.R. Kothawale Primary Data Source: India Meteorological Department Data Period: 1871-2011 Accompanying Data Files: iitm-imr-stn.txt (List of 306 raingauge stations used) iitm-regionrf.txt.gz (Monthly rainfall for homogeneous regions) iitm-subdivrf.txt.gz (Monthly rainfall of 30 meteorological subdivisions) Data Format: Data are arranged region/subdivisionwise, with a header record for each region/subdivision followed by 135 data records each record containing data for one year (12 monthly values). The following FORTRAN code extract leads to rainfall in mm/month (Data have a resolution of up to 0.1 mm/month). do is=i,nsets read(5,1)nyears,details 1 format(i3,a) do iy=1,nyears read(5,2)index,iyear,code,(rf(is,iy,m),m=1,12) 2 format(a5,i4,a1,12f5.1) enddo enddo The character variable 'details' contains the following: iitm-regionrf.txt: Name of the region; Data Period; Number of subdivisions included; Area of the region in sq. km. iitm-subdivrf.txt: Numerical Code of the subdivision; Name of the subdivision; Area of the subdivision in sq.km.; Percentage of the area out of the total area of the country; Number of stations used to compute the spatial mean; Data period. Data Description: Network of rain-gauge stations: While selecting the network of rain-gauge stations, an effort was made to select a network which would provide one representative station per district having a reliable record for the longest possible period. The network selected under these constraints consist of 306 almost uniformly distributed stations for which rainfall data are available from 1871. The hilly regions consisting of four meteorological subdivisions of India which are parallel to Himalayan mountain range have not been considered in view of the meagre rain-gauge network and low areal representation of a rain-gauge in a hilly area. Two island subdivisions far away from mainland have also not been included. Thus, the contiguous area having network of 306 stations over 30 meteorological subdivisions measures about 2,880,000 sq.km., which is about 90 percent of the total area of the country. Preparation of Subdivisional/Regional rainfall series The monthly (January - December) area weighted rainfall series for each of the 30 meteorological subdivisions have been prepared by assigning the district area as the weight for each rain-gauge station in that subdivision. Similarly assigning the subdivision area as the weight to each of the subdivisions in the region, area weighted monthly rainfall series are prepared for Homogeneous regions of India as well as for all India. IMPORTANT NOTE: The data for the recent period 1991-2010 are preliminary estimates based on the subdivisional means supplied by the India Meteorlogical Department (IMD), which are in turn based on a variable network. However, the IMD data have been rescaled to conform to the long-term means of the respective subdivisions in the IITM-IMR data set. These data will be updated as and when the full set of data for 306 stations becomes available. Key References Mooley, D. A., Parthasarathy, B., Sontakke, N. A., and Munot, A. A 1981 : Annual rain-water over India, its variability and impact on the economy. J. Climatol, 1, 167-186. Parthasarathy, B., Sontakke, N. A., Munot, A. A. and Kothawale, D. R. 1987: Droughts/floods in the summer monsoon rainfall season over different meteorological subdivisions of India for the period 1871-1984. J. Climatol, 7, 57-70. Parthasarathy, B., Rupa Kumar, K and Munot, A. A. 1993 : Homogeneous Indian Monsoon Rainfall : variability and prediction. Proc. Indian Acad. Sci. (Earth Planet. Sci.) 121-155. Parthasarathy B., Munot A.A., Kothawale D.R., 1995. All India monthly and seasonal rainfall series : 1871-1993. Theor. and Appl. Climatol., 49, 217-224. Parthasarathy B., Munot A.A., Kothawale D.R., 1995. Monthly and seasonal rainfall series for all-India homogeneous regions and meteorological subdivisions : 1871-1994. Research Report No. RR-065, Indian Institute of Tropical Meteorology, Pune, 113pp. Pant, G.B. and Rupa Kumar, K., 1997. Climates of South Asia. John Wiley & Sons, Chichester, 320 pp. Feedback: Please direct questions/problems and requests for updates to Dr. D.R. Kothawale Scientist-D Climatology & Hydrometeorology Division Indian Institute of Tropical Meteorology Homi Bhabha Road Pune 411 008, India email: kotha@tropmet.res.in Phone: +91-20-2589-3600 Ext. 353 Fax: +91-20-2586-5142 OR Dr. Rupa Kumar Kolli Scientist-F & Head Climatology & Hydrometeorology Division Indian Institute of Tropical Meteorology Homi Bhabha Road Pune 411 008, India Present Address: Chief, World Climate Applications & CLIPS Divisions, WMO, Geneva email: kolli@tropmet.res.in, RKolli@wmo.int