大高加索山脉冰川反照率时空分布及与物质平衡的关系

The spatio-temporal distribution of the albedos and its relationship with glacier mass balance in the glaciers of the Greater Caucasus Mountains

利用MOD10A1和MYD10A1冰雪反照率数据,分析了大高加索山脉地区加拉巴西冰川和德扬库特冰川的反照率时空分布特征,并使用五种反照率聚合方法,对这两条冰川2002—2019年夏季反照率与物质平衡关系开展相关性研究.结果表明,加拉巴西冰川和德扬库特冰川反照率随年份增加而明显减小,两条冰川在夏季都出现了最低反照率,加拉巴西冰川在冬季出现最高反照率,而德扬库特冰川则出现在春季;加拉巴西冰川夏季高海拔和低海拔区域的反照率差异较德扬库特冰川更为明显;两条冰川夏季反照率均与夏季物质平衡表现出一定的正相关性,其中加拉巴西冰川的相关性更加显著,使用平均最小反照率方法时两者相关系数最大可达0.874(p<0.05),德扬库特冰川使用加权平均反照率方法时两者相关系数最大为0.765(p<0.05).德扬库特冰川反照率与物质平衡相关性较低的原因可能是坡向和低海拔导致了其更易受暖湿气流影响,冰川消融中短波辐射能占比较低,反照率对其消融的影响小.

This study investigates the spatio-temporal characteristics of albedo on the Garabashi Glacier and the Djankuat Glacier in the Greater Caucasus Mountains, utilizing MOD10A1 and MYD10A1 snow/ice albedo data. Five albedo aggregation methods are applied to explore the relationship between albedos and glacier mass balance during summer from 2002 to 2019. The results reveal a clear decreasing trend in albedos retrieved from the two glaciers over the study period, with the lowest albedos observed during summer. The Garabashi Glacier exhibits the highest albedos in winter, whereas the Djankuat Glacier shows the highest albedos in spring. The variation of summer albedos between high and low altitude areas is more pronounced in the Garabashi Glacier than in the Djankuat Glacier. The summer mass balance is positively correlated with the summer albedos in both glaciers, particularly for the Garabashi Glacier. The correlation coefficient for the Garabashi Glacier reaches up to 0.874 (p < 0.05) by employing the average minimum albedo aggregation method, while for the Djankuat Glacier, it is 0.765 (p < 0.05) by utilizing the weighted average albedo aggregation method. The lower correlation of the Djankuat Glacier may be attributed to its aspect and low altitude, which make it more susceptible to warm and humid airflow, resulting in a relatively lower proportion of shortwave radiant energy in glacier melting and indicating a small influence of albedo on its ablation.