GUWAHATI, July 10 � The number of monsoon rainfall deficient years in the North-East region has been growing since 2001. Since that year, the Arunachal Pradesh meteorological sub-division of the region has recorded five monsoon rainfall deficient years, while the Assam-Meghalaya meteorological subdivision of the region recorded six monsoon rainfall deficient years with the Nagaland-Manipur-Mizoram-Tripura meteorological sub-division recording four monsoon rainfall deficient years since then.
Significantly, in the current year, each of the Arunachal Pradesh and Assam-Meghalaya subdivisions has recorded 35 per cent of deficit monsoon rainfall, while the Nagaland-Manipur-Mizoram-Tripura (NMMT) subdivision has recorded 41 per cent of deficit monsoon rainfall.
According to H Pathak, the Deputy Director General of Meteorology (DDGM) of the Regional Meteorological Centre (RMC) here, during the period between 2001 and 2011, the deficiency in monsoon rainfall of the Assam-Meghalaya subdivision has been found to be ranging between 21 per cent (2002 and 2010) and 37 per cent (2006).
Giving the breaks up of the deficient monsoon rainfall years, Pathak said that between 1982 and 1990, Arunachal Pradesh subdivision recorded one rainfall deficient year, three excess rainfall years and five normal rainfall years.
During the period, Assam-Meghalaya subdivision recorded one deficient year and eight normal rainfall years, while the NMMT subdivision recorded three rainfall deficient years, one excess rainfall year and five normal rainfall years.
Between 1991 and 2000, Arunachal Pradesh recorded one deficit rainfall year, three excess rainfall years and six normal rainfall years.
During the period, Assam-Meghalaya recorded one deficit rainfall year and nine normal rainfall years, while the NMMT recorded three deficit rainfall years and seven normal rainfall years.
Between 2001 and 2010, Arunachal Pradesh recorded five monsoon rainfall deficit years and equal number of normal rainfall years.
Assam-Meghalaya recorded, during the period, six deficit monsoon rainfall years and four normal rainfall years, while the NMMT subdivision recorded four monsoon rainfall deficit years and six normal rainfall years in that period.
When asked to explain the factors that led to such an upset in the monsoon rainfall regime in the NE region, Pathak said that the weather systems formed over the Bay of Bengal are seemed to have moved in a westward direction, drifting away from the NE region of the country.
This may be attributed to the variations occurring in the global atmospheric circulations that demand keen scientific observations for a long period and examination of at least 100 years' data relating to the intensity and movement of the weather systems, Pathak said.