CT: Climate Type; A: Area (km²); ASL: elevation above sea level (m); T: Annual average night temperature of lake waters (°C).

3.4.2. Lake area versus lake depth

Area, depth and volume of lakes have strong impact on LWST (Figure 3, Table 1). Of the lakes investigated, Lake Tonlesap (Cambodia) exhibited the highest temperature (max: 26.87°C); it is the shallowest of the lakes (around 12 m deep) and is located at the lowest elevation (4 m) (Table 2). A previous study has suggested that the annual heat budget of lakes is strongly dependent on mean depth because a deeper water column corresponds to a larger heat storage capacity (Gorham, 1964). That study further indicated a strong relationship between heat budget and lake water volume (semi-logarithmic scale) (Gorham, 1964). For deep and large lakes, more energy is needed to raise lake water temperature by one unit. Thus, less temporal variation in LWST was observed with the very large lakes, e.g., Baikal, Onega and Issyk (Figure 4 and Figure 5; Table 1). A similar line of reasoning can be advanced to explain the lower DTD values for lakes with large water volume. Lake Baikal showed slightly higher variability and DTDs than Lake Van (Eastern Turkey), but the difference was insignificant. Besides water volume, other factors (e.g., the ratio of area to mean depth, and shoreline characteristics) may have contributed to difference in LWST variability and DTDs (Leblanc, Akbarzadeh, Andrews, Lu, & Golding, 2011), and future investigations should determine the extent of these contributions.

Table 2: Information about selected typical large Eurasia lakes