Observed Trends and Variability of Temperature and Precipitation and Their Global Teleconnections in the Upper Indus Basin, Hindukush-Karakoram-Himalaya

Having an extreme topography and heterogeneous climate, the Upper Indus Basin (UIB) is more likely to be affected by climate change and it is a crucial area for climatological studies. Based on the monthly minimum temperature (T-min), maximum temperature (T-max) and precipitation from nine meteorological stations, the spatiotemporal variability of temperature and precipitation were analyzed on monthly, seasonal, and annual scales. Results show a widespread significant increasing trend of 0.14 degrees C/decade for T-max, but a significant decreasing trend of -0.08 degrees C/decade for T-min annually, during 1955-2016 for the UIB. Seasonally, warming in T-max is stronger in winter and spring, while the cooling in T-min is greater in summer and autumn. Results of seasonal T-max indicate increasing trends in winter, spring and autumn at rates of 0.38, 0.35 and 0.05 degrees C/decade, respectively, while decreasing in summer with -0.14 degrees C/decade. Moreover, seasonal T-min results indicate increasing trends in winter and spring at rates of 0.09 and 0.08 degrees C/decade, respectively, while decreasing significantly in summer and autumn at rates of -0.21 and -0.22 degrees C/decade respectively for the whole the UIB. Precipitation exhibits an increasing trend of 2.74 mm/decade annually, while, increasing in winter, summer and autumn at rates of 1.18, 2.06 and 0.62 mm/decade respectively. The warming in T-max and an increase in precipitation have been more distinct since the mid-1990s, while the cooling in T-min is observed in the UIB since the mid-1980s. Warming in the middle and higher altitude (1500-2800 m and >2800 m) are much stronger, and the increase is more obvious in regions with elevation >2800 m. The wavelet analysis illustrated sporadic inter-annual covariance of seasonal T-max, T-min and precipitation with ENSO, NAO, IOD and PDO in the UIB. The periodicities were usually constant over short timescales and discontinuous over longer timescales. This study offers a better understanding of the local climate characteristics and provides a scientific basis for government policymakers.

Automated summary

The study on the Upper Indus Basin (UIB) reveals a significant warming trend in T-max but a cooling trend in T-min. Seasonally, the warming in T-max is more pronounced in winter and spring, while the cooling in T-min is greater in summer and autumn. Precipitation shows an overall increasing trend, with greater increases in winter, summer, and autumn.