Effects of Lake Baikal on Summertime Precipitation Climatology Over the Lake Surface

Abstract

Lakes reduce temporal variations in near-surface air temperature because the heat capacity of water is larger than that of the surrounding land and can increase the amount of water vapor in the atmosphere above them through active evaporation from their surface. Owing to the thermal and humidity contrasts between a lake and its surrounding area, a lake can be anticipated to modulate weather and impact climate around it (Camberlin et al., 2018;Laird et al., 2009). Lake-induced changes in precipitation vary depending on factors such as season and geographical location of a lake. Since the atmosphere over the lake is generally warmer and more humid than that over the surrounding land in winter unless the lake is ice-covered, convection over the lake becomes more active and snowfalls prevail on the downwind side of the lake. This is referred to as lake-effect snow, readily observed for many lakes (e.g., Peace & Sykes, 1966;Steenburgh et al., 2000). In summer, on the other hand, the cool lake surface stabilizes the lower atmosphere over it, which reduces convective clouds and precipitation over the lake and its downwind area (e.g., Gu et al., 2016;Lyons, 1966). Such seasonally reversed lake effects on precipitation have been reported for midlatitude lakes such as the Great Lakes in North America (Notaro et al., 2013) and Lake Ladoga in Europe (Samuelsson et al., 2010). However, the African Great Lakes in the tropics, where neither warm nor cold seasons exist, exhibit substantial lake-induced increases in over-lake precipitation during wet seasons. This is attributed to the lake surface having ∼2.5 times greater moisture flux than the moisture flux from the equivalent land surface (Thiery et al., 2015). For lakes located in basins such as Lake Victoria, the terrain surrounding the lakes plays