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University of Twente (ITC) 2008

Response of Vegetation Phenology to Rainfall timing in the Sahel 1982 - 2004

Pant Manoj

Titre : Response of Vegetation Phenology to Rainfall timing in the Sahel 1982 - 2004

Auteur : Pant Manoj

Université de soutenance : University Twente ITC International Institute for Geo-Information Science and Earth Observation Enschede,

Grade : Master of Science (M.Sc.) 2008

Rainfall in Sahel shows inter-annual and inter-deca dal variability. Second half of the 20 th century was marked by below then average rainfall in Sahel. This extensive period (1960-1990) of desiccation plummeted into dr ought events of late sixties and early eighties. From late 1990’s the rainfall is showing a revival. The affect of the changing rainfall was seen in vegetation growth and is studied in details. The change in the rainfall condition has affected the cumulative amount as well as seasonality of rainfall. This study tries to look into response of vegetation phenology to changing rainfall timing in Sahel. The rainfall seasonality parameters were generated from Global Precipitation Climatology Project (GPCP) Pentad rainfall data, using threshold of cumulative rainfall. The phenology data was acquired 1 . To ascertain the affect of resolution, trends of rainfall seasonality were generated from GPCP pentad rainfall dataset (low resolution) and GPCP daily rainfall dataset (high resolution). The temporal trajectory for the generation of trend was taken from 1997 – 2004. However, the higher resolution da ta seems to be more sensitive, the low resolution data was able to give fairly correct trend of rainfall. Long term (1982 -2004) statistically significant tr ends were generated for rainfall seasonality and phenology. Trend in phenology and rainfall show that rainfall period in Sahel is getting longer while the growing period getting shorter. There is a strong positive correlation of SGS with ORS in Sahel, Soudan and Guinean zone, while EGS is showing strong negative correlation with ERS in Soudan. EGS in Soudan is shifting backward at a ra te of 3 to 6 days per day forward shift of ERS, while SGS is showing positive slope of 1-3 days per day forward shift of ORS. There is a lack of significant trends between EGS-ERS ; and LGS-LRS in Sahel.

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Page publiée le 27 décembre 2011, mise à jour le 30 janvier 2018