Climatology and trends in near-surface wind speed over India during 1961-2008

This study analyses near-surface wind speed changes in India during 1961 to 2008. Consisting of monthly wind speed data of 171 stations, the results show that most of the stations in India have experienced significant weakening of wind speed, both at monthly and annual timescales. All-India averaged annual mean wind speed has decreased from 9.7 kmph in 1961 to 5.0 kmph in 2008 resulting in a 49% decrease. All India averaged rate of decrease in annual mean wind speed is -0.88 kmph/decade. On monthly scale, the largest rate of decline is in June (-1.33 kmph/decade) and the smallest is in October (-0.60 kmph/decade). Spatially, large declines are found in western India, south peninsula and the coastal areas while central, southeast and northeast India have the lesser change in wind speed. Significant weakening of wind speed has occurred primarily in regions along Gujarat, Maharashtra, Tamil Nadu, north Karnataka, coastal Orissa and coastal West Bengal which also have higher annual mean wind speed. Annual mean wind speeds exceeding 15 kmph are observed only over Gujarat and south Tamil Nadu. Some parts of Rajasthan, west Madhya Pradesh, Maharashtra, north Karnataka and adjoining Andhra Pradesh and some pockets along west and east coasts experience wind speeds of 10-15 kmph. Stations having annual mean wind speed exceeding 10 kmph are rare in north India. The study evaluates climatology of winds and its long-term trends over various regions of India where wind power, can be profitably utilised. The prominent regions are in Gujarat and adjoining Madhya Pradesh, south Rajasthan, north Maharashtra, north Karnataka, south Tamil Nadu, coastal Andhra Pradesh and along the west coast from Gujarat to Goa and along the east coast from Kolkata to Nagapatinam.