Passive Microwave Remote Sensing of Soil Moisture: A Step-ByStep Detailed Methodology using AMSR-E Data over Indian SubContinent

Abstract

This paper presents a detailed methodology to process AMSR-E soil moisture data to generate average soil moisture maps of desired durations be it weekly, monthly or yearly over a large geographical area like a continent or a sub-continent. The paper also explores utility of AMSR-E soil moisture product (AE_Land 3 product) to understand the soil moisture variations over Indian subcontinent by analysing daily soil moisture data for entire calendar year of 2009. In order to demonstrate the developed methodology the year 2009 was selected wherein a total of 730 AMSR-E daily scenes (365 each for ascending as well as descending passes) were processed and analysed. Although the absolute values of soil moisture derived from AMSR-E are not showing good agreement with soil moisture status on ground which is due to large variability in soil moisture within the coarseresolution cell offered by passive sensors [1] but in general AMSR-E derived soil moisture values are well explained on the basis of rainfall data and agricultural practices adopted in different states of Indian sub-continent. The soundness of the detailed methodology proposed in this paper has been well supported by studying the variations in AMSR-E derived soil moisture with seasonal variations and rainfall data. It has been observed that the soil moisture variations are in line with the seasonal changes as well as the rainfall variations.

Variability in soil moisture using AMSR-E product- A regional case study in the province of Marathwada division, India

“…The radiometers which are referred as passive sensors generally detect the radiated energy. The Rayleigh- Jeans approximation of Planck's law is the scientific principle that functions in the process of detection by the radiometers (Singh et al, 2015). The activity is driven by the electromagnetic emission of the black body at a given temperature of T (°K) as prescribed by Planck's law.…”

“…3 for radiometers functioning in shorter wavelength ranges (Engman, 1991;E. G. Njoku et al, 2003;Sharma et al, 2018;Singh et al, 2015).…”

“…In above Eq. 4, e ¼ 1 À r ð Þ represents the emissivity depending upon medium dielectric constant (Engman, 1991;Singh et al, 2015).…”

“…Remotely sensed soil surface moisture is immensely beneficial in the fields of irrigation, hydrogeology, and meteorology. Researchers from all over the world have recently used and explored remotely sensed satellite data items, obtained in the microwave region of the electromagnetic spectrum (Singh et al, 2015;Xiao et al, 2019). Significant efforts have been made to procure goods soil moisture from satellite data in order to satisfy the community needs for worldwide reach (daily to weekly) at a higher temporal resolution (Kolassa et al, 2017).…”

Estimation of improved resolution soil moisture in vegetated areas using passive AMSR-E data

“…Therefore, in order to obtain accurate soil moisture estimates by means of remote sensing technology, retrieving multiple land surface parameters using passive microwave remote sensing observations has become a research focus. There are large number of models that retrieve soil parameters by the use of passive microwave and Singh et al (2015a) provided detailed procedure of various steps to utilize AMSR-E data.…”