Decadal differences of the diurnal temperature range in the Aral Sea region at the turn of the century

Abstract

Changes in the surface air diurnal temperature range (DTR) have been highlighted by the Intergovernmental Panel on Climate Change as critical uncertainties in climate change studies. Due to global and local factors, the regional climate in the Aral Sea region is changing intensively, providing a good case study to give a detailed description of the DTR trend and its spatial variability. Results are based on data from 33 stations at the RIHMI-WDC from 1991 to 2010. The values of DTR in the region range between about 3 °C and 18 °C, with the maxima values being observed in spring and summer. The largest differences between the two decades of the annual mean DTR are observed at the stations closest to the pre-desiccation state of the lake shoreline, especially in the south (0.6 °C dec−1). To the west of the Aral Sea, where the lakeshore has receded less, these differences are also expectedly high considering the decrease in the thermal inertia of the remaining lake (0.4 °C dec−1). To the north-east of the lake, the decadal differences of the annual mean DTR were not significant, but decadal differences of the seasonal DTR were large from February to April (–0.4 °C dec−1) coinciding with the season when the decadal differences of the mean local temperature is of 2 °C dec−1. In the south, where the artificial Sarygamysh Lake expanded during the studied period, the decadal difference of the annual mean DTR is negative. The increase in the mean temperature of all the stations between the two decades is of 0.5 °C dec−1. From August to October, in the southern and the south-eastern parts of the Aral Sea, the increase of the maximum daily temperatures was about 0.1 °C dec−1 larger than the increase of the mean temperatures