Drought is a natural phenomenon that affects ecological processes, land productivity, and human life. The phenomenon is slow to settle down and its impacts are not instantaneous, requiring an early monitoring of their signs of appearance. In order to track the effect drought on the land surface dynamics by means of surface albedo changes, we intend to exploit the VIS-channel reference image from the METEOSAT satellite data, which is an associated product of the new version of the Infrared Difference Dust Index (IDDI). The surface albedo is retrieved from the calibrated VIS-channel reference radiance, atmospherically corrected by the radiative transfer code 6S (Second Simulation of a Satellite Signal in the Solar Spectrum). In this study, we inspect the sensitivity of monthly surface albedo to drought events over a semi-arid region (M’Sila, center of northern Algeria) during the period covered by three METEOSAT satellites (5, 6, and 7). Two drought indices, SPI (Standardized Precipitation Index) and SPEI (Standardized Precipitation Evapotranspiration Index), were calculated at multiple timescales and were correlated with surface albedo over the study region. The results show that the correlation of surface albedo with the two drought indices at the timescale of 1 month (current month) is not necessarily the best indicator of the installation of a drought event. Additionally, we find that the sensitivity of surface albedo to drought indices at a medium timescales class (average of correlation coefficient at 6, 9, and 12 months), is more sensitive to SPEI index (principally 6-month timescale), during the growing season (April to September). It is also more sensitive to SPI index (principally 12-month timescale), during the supplying and charging period of water resources (October to March).

干旱是一种自然现象，会影响生态过程，土地生产力和人类生活。这种现象的消除速度很慢，其影响不是瞬间产生的，因此需要尽早监测其出现的迹象。为了通过表面反照率变化跟踪干旱对陆地表面动力学的影响，我们打算从METEOSAT卫星数据中利用VIS通道参考图像，该图像是新版红外差异粉尘指数的关联产品（IDDI）。从经校准的VIS通道参考辐射率检索表面反照率，该辐射率通过辐射转移代码6S（太阳光谱中卫星信号的第二次模拟）在大气中进行了校正。在这项研究中，我们检查了半干旱地区月度表面反照率对干旱事件的敏感性（M'Sila，在三颗METEOSAT卫星（5、6和7）覆盖的时期内。在多个时间尺度上计算了两个干旱指数SPI（标准降水指数）和SPEI（标准降水蒸散指数），并与研究区域的地表反照率相关。结果表明，在1个月（当月）的时间尺度上，地表反照率与两个干旱指数的相关性并不一定是干旱事件发生的最佳指标。此外，我们发现，在生长期间，中等时标等级（相关系数在6、9和12个月的平均值）对地表反照率对干旱指数的敏感性更加敏感。季节（4月至9月）。