Improving the accuracy of glacier surface temperature retrieval and quantifying its terrain influence: Case studies of Qiyi Glacier and glaciers on Muztagh Ata

: Glacier Surface Temperature (GST) not only directly reflects climate change but also influences the energy and mass balance of glaciers. However, existing Land Surface Temperature (LST) products and algorithms exhibit systematic biases in high-altitude glacier regions and cannot support the fine-scale research on glaciers in High Mountain Asia (HMA). In this study, an improved long-term GST retrieval method was proposed using the Google Earth Engine (GEE) platform: atmospheric parameters were directly extracted from Landsat 7/8 products to eliminate the MODTRAN simulation process, and MOD05 water vapor data were coupled to correct atmospheric transmittance; a snow/ice surface classification strategy was introduced to reconstruct emissivity. Validation against Automatic Weather Station (AWS) observations shows that the improved method achieves an RMSE of 1. 45 K, reducing the error by approximately 0. 23 K compared with the Landsat 7/8 C2 L2 STB6/STB10 products. Based on this algorithm, GST for Muztagh Ata and the Qiyi Glacier from 2000 to 2024 was retrieved, and the controlling effects of topography and microtopography were quantified. The results indicated that from 2000 to 2024, the mean GST of Muztagh Ata and the Qiyi Glacier were 261. 19 ± 5. 53 K and 259. 97 ± 1. 96 K, respectively. At the macro-topographic scale, the northwest slope of Muztagh Ata exhibits the largest GST lapse rate with elevation (−0. 8 K per 100 m) ; at the same elevation, the southeast slope shows notably higher GST than other slope aspects. Moreover, debris-covered areas on Muztagh Ata have higher temperatures than bare-ice zones, resulting in an overall GST increase of 1. 57 K for the glacier. At the microtopographic scale, taking the predominantly north-facing Qiyi Glacier as an example, local topographic undulations (i. e. , microtopographic variations) can induce GST perturbations of up to 3. 14 K at the same elevation. This study provides robust technical support for the production of large-scale, long-term, high-precision GST products and for research on the response mechanisms of the cryosphere to climate change.