摘要：Understanding seasonal variations in the evaporation of inland waters (e.g., lakes and
reservoirs) is important for water resource management as well as the prediction
of the hydrological cycles in response to climate change. We analyzed eddy
covariance-based evaporation measurements from the Ross Barnett Reservoir (32°26'N,
90°02'W; which is always ice-free) in central Mississippi during the cool months (i.e.,
September–March) of 2007 and 2008, and found that the variability in cold front
activities (i.e., passages of cold fronts and cold/dry air masses behind cold
fronts) played an important role in modulating the exchange of sensible (H) and
latent (λE) heat fluxes. Our analysis showed that 2007's warmer cool season had smaller mean
H and
λE than 2008's cooler cool season. This implies that the warmer cool season did
not accelerate evaporation and heat exchange between the water surface and
the atmosphere. Instead, more frequent cold fronts and longer periods of
cold/dry air masses behind the cold fronts in 2008 resulted in overall larger
H and
λE as compared with 2007, this primarily taking the form of sporadic short-term rapid 'pulses' of
H and
λE losses from the water's surface. These results suggest that future climate-induced changes
in frequency of cold fronts and the meteorological properties of the air masses behind cold
fronts (e.g., wind speeds, temperature, and humidity), rather than other factors of climate
change, would produce significant variations in the water surface's energy fluxes and
subsequent evaporation rates.
