Spatial and Temporal Variability of Net Primary Productivity (NPP) over Terrestrial Biosphere of India Using NOAA-AVHRR Based GloPEM Model |
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Authors: | R P Singh S Rovshan S K Goroshi S Panigrahy J S Parihar |
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Institution: | (1) Space Applications Centre, ISRO, Ahmedabad, 380015, India;(2) National Aerocosmic Agency of Azerbaijan, Baku, Azerbaijan |
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Abstract: | The monitoring of terrestrial carbon dynamics is important in studies related with global climate change. This paper presents
results of the inter-annual variability of Net Primary Productivity (NPP) from 1981 to 2000 derived using observations from
NOAA-AVHRR data using Global Production Efficiency Model (GloPEM). The GloPEM model is based on physiological principles and
uses the production efficiency concept, in which the canopy absorption of photosynthetically active radiation (APAR) is used
with a conversion “efficiency” to estimate Gross Primary Production (GPP). NPP derived from GloPEM model over India showed
maximum NPP about 3,000 gCm−2year−1 in west Bengal and lowest up to 500 gCm−2year−1 in Rajasthan. The India averaged NPP varied from 1,084.7 gCm−2year−1 to 1,390.8 gCm−2year−1 in the corresponding years of 1983 and 1998 respectively. The regression analysis of the 20 year NPP variability showed significant
increase in NPP over India (r = 0.7, F = 17.53, p < 0.001). The mean rate of increase was observed as 10.43 gCm−2year−1. Carbon fixation ability of terrestrial ecosystem of India is increasing with rate of 34.3 TgC annually (t = 4.18, p < 0.001). The estimated net carbon fixation over Indian landmass ranged from 3.56 PgC (in 1983) to 4.57 PgC (in 1998). Grid
level temporal correlation analysis showed that agricultural regions are the source of increase in terrestrial NPP of India.
Parts of forest regions (Himalayan in Nepal, north east India) are relatively less influenced over the study period and showed
lower or negative correlation (trend). Finding of the study would provide valuable input in understanding the global change
associated with vegetation activities as a sink for atmospheric carbon dioxide. |
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