Soil–vegetation moisture capacitor maintains dry season vegetation productivity over India

Abstract

India receives more than 70% of its annual rainfall in the summer monsoon from June to September. The rainfall is scanty and scattered for the rest of the year. Combining satellite data and model simulations, we show that the soil-vegetation continuum works as a natural capacitor of water, storing the monsoon pulse and releasing the moisture to the atmosphere through evapotranspiration over approximately 135 days when the moisture supply from precipitation is less than the evapotranspiration losses. The total Gross Primary Productivity of vegetation in India during the capacitor period accounts for almost 35% of the total annual GPP value. It primarily depends on the soil moisture at the beginning of the period, a measure of moisture capacitance of soil, with a correlation of 0.6. Given that India is the second largest contributor to recent global greening, its soil-vegetation water capacitance plays a significant role in the global carbon balance.

Plot-Scale Irrigation Dates and Amount Detection Using Surface Soil Moisture Derived from Sentinel-1 SAR Data in the Optirrig Crop Model

“…Moreover, the temporal dynamics of vegetation, including growth stages, leaf area index, and canopy density, can also introduce uncertainties in SSM simulations. Vegetation plays a crucial role in the water balance of the soil-plant-atmosphere system, as it affects evapotranspiration rates and soil moisture depletion in crop models [103], such as Optirrig. However, accurately representing the dynamics of vegetation within the model is challenging.…”