Warm Island Effect in the Badain Jaran Desert Lake Group Region Inferred from the Accumulated Temperature

Abstract

The Badain Jaran Desert (BJD) is characterized by the coexistence of over 110 perennial lakes and thousands of megadunes in its southeast part. Unlike the cold island effect, we found a special phenomenon of the warm island effect in the lake group region of the BJD. However, the concept and formation mechanism remains unclear. In this study, based on observations of land surface processes in the area, we first used the daily mean temperature from 23 automated meteorological stations from 2010 to 2017 to calculate the mean daily temperature (T) ≥ 0 °C, T ≥ 10 °C accumulated temperature and negative accumulated temperature. Furthermore, using the net radiation from two eddy covariance measurement systems, characteristics of the net radiation between the lake and megadunes were analyzed. When comparing observed data in the lake group region to surrounding areas, accumulated temperature from all three meteorological stations in the lake group region were higher; the duration days of T ≥ 0 °C and T ≥ 10 °C were longer, whereas duration days of negative accumulated temperature were shorter. In addition, the initial dates for T ≥ 0 °C and T ≥ 10 °C accumulated temperature were earlier, whereas the end dates were delayed. Variations in heat were observed between stations in the lake group region that may be reflective of microclimate environments between lakes. The authors relate warm island formation in the BJD lake group region to (1) the heat carried by groundwater recharge to the desert lake groups has a great impact on the local temperature. (2) Net heat radiation to the atmosphere through sensible heat flux owing to sparse vegetation in the desert areas. Hence, heat resources are richer in the lake group region. This study aims to improve our understanding of the warm island effect from a comprehensive analysis of its intensity and distribution pattern around the lake group region as compared to its surroundings. In addition, the results from this study will provide a scientific basis for determining the source of lake water in the BJD.

Warm Island Effect in the Lake Region of the Tengger Desert Based on MODIS and Meteorological Station Data

“…Thus, this is regarded as the study area in the lake area, and the lake area is defined with a 10 km buffer zone from the lakes. Furthermore, the lake area is a blend of surfaces (both water and land) [9,12]. The northern part of the desert has fewer lakes than other areas [25]; Thus, the non-lake area is defined as the northern desert area adjacent to the lake-group region (Figure 1).…”

“…The lake surface reflectance is smaller than that of the land surface; the radiation absorbed by the water surface is more than the net radiation absorbed by the land surface which is confirmed. Liang et al (2020) analysed the annual variation characteristics of monthly net radiation from both land and lake stations in the hinterland of the BJD (Figure 8); they found that the net radiation at the lake station (E1) was much higher than that of the land station (E2). The total annual net radiation of the E1 station (2937.5 MJ/m 2 ) was more than twice that of the E2 station (1340.3 MJ/m 2 ); the difference was larger in summer and smaller in winter [11].…”

“…For example, a study of Landsat satellite remote sensing data by Deng et al (2018) found that the surface temperature in the lake-group region is higher than that of the non-lake area in the northern part of the desert [10]. Liang et al (2016Liang et al ( , 2020 indicated that the annual and seasonal average temperatures in the lake-group region were higher than those of the surrounding area, and believed that the mechanism of the warm island effect was related to two aspects: First, heat is carried by the groundwater recharge to the desert lake groups. Second, due to the sparse vegetation and arid surface of the desert hinterland, most of the net radiation is transferred to the atmosphere through sensible heat flux.…”

“…Second, due to the sparse vegetation and arid surface of the desert hinterland, most of the net radiation is transferred to the atmosphere through sensible heat flux. Meteorological observations found that accumulated temperatures of ≥0 • C and ≥10 • C and phenological observations also proved the existence of a warm island effect in the lake-group region [11][12][13]. Zhao et al (2021) found that the lake region has a warm island effect in winter, and is more intense at night [14].…”

Warm island effect observed in lake areas of the Badain Jaran Desert, China

“…Recent research in the Badain Jaran Desert (BJD) in China have reported air temperatures in the lake areas to be significantly higher than in the surrounding region and as a result, the 'warm island effect' concept was introduced. Zhang et al (2015) and Liang et al (2020) have shown that the winter surface air temperature and accumulated air temperature in the BJD lake area are higher than those in surrounding areas. This may be related to the deep groundwater which recharges the lakes.…”