Inter‐annual variability in snow cover depletion patterns and atmospheric circulation indices in the Upper Irtysh basin, Central Asia

Abstract

The Irtysh River is the main water resource of Eastern Kazakhstan and its upper basin is severely affected by spring floods each year, primarily as a result of snowmelt. Knowledge of the large‐scale processes that influence the timing of these snow‐induced floods is currently lacking, but critical for the management of water resources in the area. In this study, we evaluated the variability in winter–spring snow cover in five major sub‐basins of the Upper Irtysh basin between 2000 and 2017 as a possible explanatory factor of spring flood events, assessing the time of peak snow cover depletion rate and snow cover disappearance from the moderate‐resolution imaging spectroradiometer (MODIS) MOD10A2 data set. We found that on average, peak snow cover retreat occurs between 22 March and 14 April depending on the basin, with large interannual variations but no clear trend over the MODIS period, while our comparative analysis of longer‐term snow cover extent from the National Oceanic and Atmospheric Administration Climate Data Record data set suggests a shift to earlier snow cover disappearance since the 1970s. In contrast, the annual peak snow cover depletion rate displays a weak increasing trend over the study period and exceeded 5,900 km2/day in 2017. The timing of snow disappearance in spring shows significant correlations of up to 0.82 for the largest basin with winter indices of the Arctic Oscillation (AO) over the region. The primary driver is the impact of the large‐scale pressure anomalies upon the mean spring (MAM) air temperatures and resultant timing of snow cover disappearance, particularly at elevations 500–2,000 m above sea level. This suggests a lagged effect of this atmospheric circulation pattern in spring snow cover retreat. The winter AO index could therefore be incorporated into long‐term runoff forecasts for the Irtysh. Our approach is easily transferable to other similar catchments and could support flood management strategies in Kazakhstan and other countries.

Snow Cover Variability in the Greater Alpine Region in the MODIS Era (2000–2019)

“…These activities are, in fact, dependent on the snow depth and distribution, and they are severely affected by the current climate change, which can lead to a reduction in snow cover as the increasing air temperature leads to more precipitation falling as rain and earlier snowmelt in the spring [14]. Moreover, snow may cause natural disasters such as avalanches or floods as a consequence of the melting process [15,16].…”

“…Compared to AVHRR, MODIS benefits from a finer spatial resolution (500 m) and the availability of validated snow cover products such as MOD10A1 [25], and although it has a shorter period of data coverage (since 2000), it has now reached 20 years in orbit, building an invaluable data record and approaching the minimum time required for climatological analysis. Several studies have employed MODIS, based on either the daily or the 8-day product, to investigate the spatial distribution and interannual variability in snow cover at the regional scale and to estimate the runoff characteristics [16,26,27]. Some studies have also included the Alps as part of a larger area: for instance, Dietz et al [28] observed snow cover characteristics in Europe from 2000 to 2011, while Notarnicola et al [29] investigated snow cover changes over major mountain chains of the planet from 2000 to 2018.…”

Comparing Measured Incoming Shortwave and Longwave Radiation on a Glacier Surface with Estimated Records from Satellite and Off-Glacier Observations: A Case Study for the Forni Glacier, Italy

“…Satellite images permitted the description of glacier albedo [48][49][50], which is diminishing in the Alps [51] due to increasing debris and black carbon deposition. Furthermore, remote sensing highly improved snow cover mapping, thus permitting researchers to describe snow depletion and to compute more accurately the water budget of a mountain catchment [52][53][54][55][56][57][58][59][60].…”