Snow/ice cover is an integral part of the Earth’s climate system. Earth’s snow/ice cover helps regulate the energy exchange between the Earth’s surface and the atmosphere, directly regulating the surface (and near-surface) temperatures. This study utilizes measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43C3 dataset to derive the albedo and snow cover variation over the past two decades (2001–2020). The snow cover and the albedo vary with local seasonal variation. The global and the southern hemisphere albedo drops by about 17.4% and 26.9%, respectively, during 2017–2020. However, the northern hemisphere albedo drops by about 10.3% from 2017 to 2019 and then increases by about 14.2% in 2020. For non-glaciated regions, the albedo drops from 2017 to 2019 is maximum during JJA (23.5%), followed by SON (19.2%), DJF (12.7%), and MAM (7.1%) months averages. The non-glaciated albedo in the southern hemisphere falls (2016 onwards) by about 40.6%, 47.5%, 55.8%, 30.8% for DJF, MAM, JJA, and SON month averages, respectively. Since the snow cover variation is minimal in the past two decades, an increase in the Northern Hemisphere’s albedo in 2020 indicates a relatively fresher snow presence on the surface compared to previous years.

冰雪覆盖层是地球气候系统不可或缺的一部分。地球的冰雪覆盖层有助于调节地球表面与大气之间的能量交换，直接调节表面（和近地表）的温度。这项研究利用了中等分辨率成像光谱仪（MODIS）MCD43C3数据集的测量结果，得出了过去二十年（2001-2020年）的反照率和积雪变化。积雪和反照率随当地季节变化而变化。在2017–2020年期间，全球和南半球的反照率分别下降了约17.4％和26.9％。但是，北半球的反照率从2017年到2019年下降约10.3％，然后在2020年增加约14.2％。对于非冰川地区，JJA期间从2017年到2019年的反照率下降最大（23.5％），其次是SON （19.2％），道琼斯（12。7％）和MAM（7.1％）个月的平均值。DJF，MAM，JJA和SON月平均数分别在南半球的非冰川反照率（2016年起）分别下降约40.6％，47.5％，55.8％，30.8％。由于过去两年的积雪变化很小，因此北半球2020年反照率的增加表明与前几年相比，地表雪的存在相对较新鲜。