Publications

Kumari, M; Chakraborty, A; Chakravarathi, V; Roy, PS (2023). Spatio-temporal trend of crop phenology, SPEI, and their interactions over different agro-ecological regions of India. THEORETICAL AND APPLIED CLIMATOLOGY, 154(1-2), 291-309.

Abstract
The study focuses on analyzing the impact of dryness/wetness, derived from Standardized Precipitation Evapotranspiration Index (SPEI), on vegetation phenology in different agro-ecological zones (AERs) of India during 2001-2018. Long-term CRU TS3 SPEI datasets at a 3-month time scale were used to characterize the drought events, while Normalized Difference Vegetation Index (NDVI) data from MODIS at a 250 m scale was used to extract crop phenology metrics. The results revealed that the dryness was prevalent in the hot sub-humid regions since the new millennium. Non-parametric trend analysis showed that northeast India experienced the highest increase in drought events over the past 38 years. In terms of phenology metrics, approximately 59, 23, and 61% of agricultural areas displayed an increasing trend of the start of season (SoS), seasonal NDVI amplitude (NDVImax), and length of season (LoS). However, 21% of agricultural area showed a decreasing trend in SoS, 5.17% in NDVImax, and 28% in LoS. The impact of climate extremes varied across different AERs, that too in dry and wet years. During drought years, most AERs exhibited a delayed SoS, reduced NDVImax, and decreased LoS. The sensitivity of LoS to dryness is higher in semi-arid and sub-humid regions compared to arid and humid regions. Under the projected increase in extreme events, understanding resilient crop growth in response to dryness/wetness is crucial for adaptation and mitigation strategies. The findings of this study help in identifying areas that are particularly vulnerable to drought events and can contribute in informed decision-making.

DOI:
10.1007/s00704-023-04557-3

ISSN:
1434-4483