Centre for Atmospheric Sciences Indian Institute of Technology Delhi Hauz Khas, New Delhi – S K Dash Some Evidences of Climate Changes in India which may be used for Model Verifications

The Main Topics of Discussion are :  Meteorological Parameters  Extreme Weather Events  Water Availability  Ecosystems  Coastal Zone Studies  Wildlife Health  Medicinal Plants  Desertification  Glaciers  Mitigation Strategies

Meteorological Parameters :  Long term observed data show that the maximum temperature over India has increasing trend whereas the minimum temperature does not show any definite changing pattern.  The Indian summer monsoon rainfall does not show any definite increasing/decreasing trend which can be attributed to global warming.  There are evidences of winter/spring rainfall increase and monsoon rain decrease in the Doon valley during the last 70 years.

 Analysis of observed data from shows increase in the number of extra-tropical cyclones/winter-storms, but decrease in tropical cyclones. Also pre-monsoon and post- monsoon cyclones increase in number Extreme Weather Events :  The monsoonal disturbances such as number of lows, depressions, cyclones or severe cyclonic storms do not show any definite increasing/decreasing trend. However it is necessary to examine the occurrence of only the extreme weather events such as heat wave conditions, severe cyclonic storms or super-cyclones vis-à- vis the climate change.

Figure 1 Highest maximum temperature recorded at some stations of Andhra Pradesh and Orissa during heat wave (May 19 - June 10, 2003).Stations considered are Ongole (ONG), Kakinada (KND), Machillipatanam (MPT), Gannavaram (GNV), Nellore (NLR) Titilagarh (TTG), Hanumankunda (HNK).

Figure 2 Highest maximum temperature recorded at some stations during heat wave of Andhra Pradesh in May & June 2003 and the earlier recorded highest maximum temperature.

Figure 3 Highest maximum temperature recorded at some stations during heat wave of Orissa in May & June 1998 and the earlier recorded highest maximum temperature.

Figure 4 Percentage frequencies of number of days with horizontal visibility < 2000 m at 0300 UTC during winter season with significant trends at 99% level. De et al (2001).

Figure 5 Variation of the number of fog days in the month of January for 1989 to 2003 at New Delhi and the corresponding 5-year running mean values.

Figure 6 Trends of average duration of visibility (hrs / day) < 200 meters for 1964 to 1998 at Delhi. Source: Singh (2001).

Figure 7 Percentage deparature of Indian summer monsoon rainfall from its mean value for 1900 to 2003 and running mean values over different periods.

Figure 8 Percentage of area of the country under moderate and severe drought for the period

Figure 9 Eleven year running means of annual frequency of disturbances with the minimum intensity of depressions and cyclonic storms formed over he Indian region ( ).

Figure 10 Eleven Year running means of frequency of monsoon depressions formed during June to September ( ).

Figure 11 Eleven year running means of frequency of disturbances with the minimum intensity of cyclonic storms formed in the months of May, October & November ( ).

Figure 12 Eleven year running means of frequency of disturbances with the intensity of depressions and above formed in the months May, October and November during