Publications

This study aims to address gaps in assessing the accuracy of satellite-based soil moisture data by utilizing machine learning techniques to generate spatially complete error maps for Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Advanced Scatterometer (ASCAT) systems, and by examining the influence of environmental conditions on satellite-based soil moisture retrievals, revealing that a significant portion of missing error information from triple collocation analysis (TCA) can be reconstructed using ensemble prediction mean of machine learning models, contributing to a more comprehensive understanding of soil moisture dynamics across the three satellite missions.

Accurately estimating soil moisture from satellite data is crucial for various Earth science disciplines. This study introduces a Bayesian approach to analyze error characteristics in widely used satellite-derived soil moisture data. By applying Bayesian hierarchical modeling and triple collocation analysis, the study examines the influence of environmental factors and human activities on data accuracy. The findings highlight the adaptability and potential of Bayesian modeling for sensitivity analysis in remote sensing research. The study also identifies factors like irrigation, vegetation, and retrieval algorithm assumptions as sources of errors. It emphasizes the need to consider multiple factors when assessing data quality. Overall, the research provides a valuable framework for investigating error characteristics in satellite-based soil moisture data.

In many protected areas and rivers with non-constant flow, there is limited ground data, making it hard to get streamflow information. This study looks at using streamflow data from regions with lots of information (North America, South America, and Western Europe) to help estimate streamflow in areas with less data (South Africa and Central Asia). By using machine learning algorithms trained on climate and catchment attributes from data-rich areas, we found they could effectively estimate monthly streamflow in data-poor regions. This study helps guide the selection of input data and machine learning methods for estimating streamflow in different geographic locations.

Estimating soil moisture from space using various microwave wavelengths is essential for predicting natural disasters and analyzing the Earth's water cycle. This study examines how well space-based technology can measure soil moisture (SM) and how it performs in different environments. It found that AMSR2 C-band products work better in areas with more vegetation, while X-band products are less effective. In areas with little vegetation, all AMSR2 products have weaker performance because of their limitations in detecting moisture in dry soil. The study also found that daytime measurements work better in areas with less vegetation, while nighttime measurements are more effective in densely vegetated areas. By using different products based on their strengths and weaknesses, researchers can improve the accuracy of soil moisture measurements, but this may result in reduced coverage of the area being studied.

Estimating precipitation from space using microwave satellite systems is essential for managing water resources, predicting natural disasters, and analyzing the Earth's water cycle. This study compares two algorithms, SM2RAIN and SM2RAIN-NWF, for estimating rainfall using soil moisture data. The newer SM2RAIN-NWF algorithm offers improved results by combining SM2RAIN with a net water flux model. We found that SM2RAIN-NWF performed better than SM2RAIN, especially in arid and semi-arid regions. The study also discovered that drainage played a crucial role in improving rainfall estimates, while evapotranspiration had a minimal impact.

Rainfall estimation using remote sensing technology offers a more accurate alternative to traditional measurement methods due to its high resolution in both time and space. The SMA2RAIN-NWF algorithm, an improved version of the original SM2RAIN algorithm, uses satellite soil moisture data to estimate rainfall. This study aims to evaluate the effectiveness of SMA2RAIN-NWF using multiple soil moisture products and different aggregation periods. The results show that the algorithm performs better as the aggregation levels increase and that it is more effective in urban areas. Overall, the SMA2RAIN-NWF algorithm demonstrates improved performance compared to the original SM2RAIN algorithm.