Abstract/Summary

Global retreat in glaciers is considered to be one of the critical indicators of climate change. However, the glaciers of the Karakoram (KR) region of Karakoram-Himalayas (KH) stand out because of their divergent response, displaying a surge in glaciers there as opposed to glaciers in other regions. This phenomenon is known as the "Karakoram Anomaly." Although many factors control the establishment and sustenance of the anomaly, the present study establishes winter precipitation associated with Western Disturbances (WDs) over the KH as one of the key drivers behind its emergence. To examine the role of WDs, a tracking algorithm is applied to 39-seasons (Nov-Mar) for three independent (ERA5, MERRA2, and NCEP-CFSR/CFSv2) reanalyses datasets. The associated ensemble statistics generated in terms of their intensity, precipitation/snowfall volumes, and wind-speed suggest a revival in recent years over the core-anomaly regions. However, the frequency has remained steady. The KR witnessed a rise of 10.17% in precipitation intensity associated with WDs in recent decades. The high percentage of snowfall received by KR (64.49%) through WDs in the total seasonal snowfall plays a crucial role in modulating the regional mass-balance anomaly. Simultaneously, the contribution of snowfall from non-WD sources in the KR has had a statistically significant decline of 17.39% in recent decades, coinciding with the anomaly period. The enhanced intensity of WDs is found to be associated with changes in increased upper-tropospheric baroclinic instability and a shift of the Subtropical Westerly Jet mean latitudinal position. The moisture-carrying capacity is also found to be enhanced.