A Triple Collocation-Based Comparison of Three L-Band Soil Moisture Datasets, SMAP, SMOS-IC, and SMOS, Over Varied Climates and Land Covers

Soil moisture plays an important role in the hydrologic water cycle. Relative to in-situ soil measurements, remote sensing has been only means of monitoring global scale near real-time over past 40 years. Among these, products from radiometry sensors operating at L-band, e.g., SMAP, SMOS, and SMOS-IC, are theoretically established be more advantageous than previous C/X-band products. However, little effort made investigate inter-product differences L-band retrievals provide insights into optimal use these In this regard, study aims identify relative strengths weaknesses three across diverse climate zones land covers using triple collocation analysis. Results show that SMOS-IC exhibits significantly improved estimation skills, original SMOS product. This demonstrates paramount importance retrieval algorithm development improving estimates—given both same brightness temperature information. SMAP is superior 69% surface terms error variances. tends outperform temperate/arid regions including east North America, South western Africa, northern China, central Australia. Additionally, considerable performance degradation all data observed unvegetated areas. may suggest accuracy arid semi-arid should a key priority for future development, model-based (e.g., GLDAS) appear accurate estimates regions.