Title: Long-term rainfall trends of Indian urban station and its variation in different phases and seasons

Authors: A. Ramachandran; J. Anushiya

Addresses: Centre for Climate Change and Adaptation Research, CEG Campus, Anna University, Chennai-600 025, Tamil Nadu, India ' Centre for Climate Change and Adaptation Research, CEG Campus, Anna University, Chennai-600 025, Tamil Nadu, India

Abstract: This work studies rainfall trends for 196 years (1813 to 2009) of Meenambakkam Station, an old observatory located in Chennai, which is the fourth largest Metropolis in India. Precipitation data have been studied on the basis of months, seasons and periods. Long-term trends in rainfall were determined by Mann-Kendall rank statistics and linear regression. There is a significant increase of long-term annual and monsoon rainfall and insignificant increase of winter and post monsoon rainfall. Post monsoon, the main rainy season of Chennai contributes 59.8% of the annual rainfall, while contribution decreases to 57.6% in 1951 to 2009 and a further decrease to 54.7% in the last nine years. Summer rainfall shows decreasing trend. Further, this study tries to find for an explanation for precipitation trends by two global climate phenomena, IOD and PDO. Annual rainfall has significant positive correlation with PDO and insignificant negative correlation with IOD. Rainfall in post monsoon season has significant positive correlation with PDO. The negative PDO (−PDO) phases show a decrease in rainfall and positive phases shows excess rainfall. Teleconnections with other global indices have to be studied further and deeper.

Keywords: long-term trends; seasonal variation; time periods; Indian Ocean Dipole; IOD; Pacific Decadal Oscillation; PDO; India; rainfall trends; urban rainfall; cities; historical data.

DOI: 10.1504/IJGW.2015.069364

International Journal of Global Warming, 2015 Vol.7 No.3, pp.307 - 321

Received: 04 Feb 2013
Accepted: 22 Jun 2013
Published online: 14 May 2015 *

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