[A-CG41] Satellite Earth Environment Observation

[ACG41-10] Evaluation of potential new AMSR snow depth validation sites at the Carman study sites within the RISMA network in southern Canada

*Takumi Suzuki¹, Rigen Shimada¹, Misako Kachi¹ (1.Japan Aerospace Exploration Agency (JAXA), Earth Observation Research Center (EORC))

Keywords:AMSR, Microwave, Snow depth, Snow melting, Canada

The Advanced Microwave Scanning Radiometer (AMSR) series has been monitoring various physical quantities related to the global water cycle for over two decades. AMSR3, which will be on board the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW) scheduled for launch in 2025, is expected to continue these observations. To validate AMSR3 snow depth measurements, the new validation sites are proposed at the Carman sites within the RISMA network in southern Canada. This study aims to investigate the historical variability in AMSR snow depth at the Carman sites, identify any anomalies or snowmelt timings, and evaluate the effectiveness of these sites as validation locations. Data were collected from 2002 to 2025. AMSR data were obtained for eight pixels within a 0.1° grid encompassing the Carman sites. To analyze air temperature changes, re-analysis data were acquired from four pixels within a 0.5° grid containing the Carman sites. Historical maximum snow depths ranged from approx. 20 to 50 cm, indicating relatively low snow depths at the sites. Typically, snow depths record nearly zero during the summer. However, an unusually high snow depth was recorded on June 16, 2024. Additionally, brightness temperatures at 89GHz - H/V on the same day were significantly lower. These findings suggest that anomalous snow depth values may occur when thick clouds are present in the atmosphere in summer. Historical snowmelt trends at the Carman sites were analyzed using Diurnal Amplitude Variation (DAV), defined as the difference between daytime and nighttime brightness temperatures at 36GHz - V. DAV values increased at the end of the snow cover period, when air temperatures approached 0°C. In some years, DAV values above 20 (Indicates snow melting) was experienced between January and February, but it is most common during March and April. These results indicate that the Carman sites are suitable for verifying low snow depths in low-latitude regions. After the launch of GOSAT-GW, this new validation sites will be used effectively to improve the accuracy of AMSR snow depth products.