ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture 339 DERIVING PHENOLOGY METRICS AND THEIR TRENDS USING TIMES SERIES OF AVHRR-NDVI DATA

In this study, an attempt has been made to derive the spatial patterns of temporal trends in phenology metrics and productivity of crops grown, at disaggregated level in Indo-Gangetic Plains of India (IGP), which are helpful in understanding the impact of climatic, ecological and socio-economic drivers. The NOAA-AVHRR NDVI PAL dataset from 1982 to 2001 available at a pixel size of 8x8 km and at an interval of 10 days was stacked together as per the crop year (June to May) and subjected to Savitzky-Golay filtering to remove residual noise. For crop pixels, maximum and minimum values of NDVI, their time of occurrence and total duration of kharif (June-October) and rabi (November – April) crop seasons were derived for each crop year. These derived parameters were subjected to pixel-wise linear regression with time to derive the rate and direction of change. The maximum NDVI value is showing moderate to high increasing trends across IGP during both kharif and rabi seasons indicating an increase in productivity of crops. The trends in time of occurrence of peak NDVI during kharif dominated with rice is showing that the maximum vegetative growth stage is happening early across most of Punjab, North Haryana, Parts of Central and East Uttar Pradesh and some parts of Bihar and West Bengal. Only central parts of Haryana are showing a delay in occurrence of maximum vegetative stage. During rabi, no significant trends in occurrence of peak NDVI are observed in most of Punjab and Haryana except in South Punjab and North Haryana where early occurrence of peak NDVI is observed. Most parts of Central and Eastern UP, North Bihar and West Bengal are showing a delay in occurrence of peak NDVI. In general, the rice dominating system is showing an increase in duration in Punjab, Haryana, Wesetrn UP, Central UP and South Bihar whereas in some parts of North Bihar and West Bengal a decrease in the duration is also observed. During rabi season, except Punjab, the wheat dominating system is showing a decreasing trend in crop duration. *[email protected]