Abstract
Cyclone global navigation satellite system (CYGNSS) has provided a valuable opportunity for high spatiotemporal monitoring of land surface reflectivity over the past few years. CYGNSS with a constellation of eight microsatellites is able to constantly observe the “scattered” global positioning system signals from the land. In this study, we validate the CYGNSS land reflectivity data in Australia for mapping the spatial extent of the inundated area and for determining temporal changes in surface soil moisture. CYGNSS level 1 data acquired for the period of 2017–2020 is assessed against various measurements, including satellite and ground-based measurements. Empirical mode decomposition is used to better analyze the CYGNSS time series and their relationship with the independent measurements. Furthermore, the mission's ability to capture surface reflectivity changes in response to extreme climatic events is analyzed. The results show that high spatial and temporal resolution CYGNSS data can largely represent the top layer ( $\sim$ 5 cm) soil moisture spatial and temporal variations close to soil moisture active passive. CYGNSS surface reflectivity results are also found to be sensitive to surface water changes and able to depict inundated land surface.
Highlights
M ONITORING land surface changes is crucial for successful hydroclimate modeling and weather forecasting
We further investigate the application of Cyclone global navigation satellite system (CYGNSS) data for inundation mapping as well as surface water changes due to extreme climatic events such as intense precipitation.Importantly, a more deeply analyze of the time series is carried out using empirical mode decomposition (EMD) to decompose the signals and unravel their hidden quasi-periodicity and features
We examined the CYGNSS surface reflectivity measurements by comparing them with various other datasets in Australia
Summary
M ONITORING land surface changes is crucial for successful hydroclimate modeling and weather forecasting. Changes in soil moisture and inundated areas have an important impact on a region’s hydrology and climate as a result of the interaction between the land and atmosphere [1]–[3]. Constant and accurate monitoring of such variables is necessary for better hydrologic, climate as well as land-atmosphere coupled modeling [4], [5]. Satellite remote sensing with more than three decades of data, high spatiotemporal resolution, and extended coverage are great tools to help scientists with such monitoring. With the recent development in small satellite technologies, there is a great opportunity for cost-effective. Manuscript received June 10, 2021; revised July 29, 2021, September 14, 2021, and September 23, 2021; accepted September 28, 2021. Date of publication October 8, 2021; date of current version October 25, 2021. (Corresponding author: Mehdi Khaki.)
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