冰冻圈水循环在全球尺度的水文效应
摘要
Freeze-melt processes of the cryosphere have important impacts on hydrological processes of oceans and rivers, as well as the atmospheric water cycle. Based on analysis of the composition of freshwater in oceans of the polar regions, the effect of the cryosphere on freshwater input to polar oceans is analyzed. Further, the relationship between the cryosphere and ocean thermohaline circulation is interpreted and the cryosphere contribution to sea level rise is discussed. In the freshwater cycle of the Antarctic and Arctic oceans from 60° to 90° latitude, Arctic sea ice and snow meltwater greatly exceeds water in the precipitation-evaporation process in the water cycle. Arctic snowmelt, river recharge, mountain glaciers, ice caps and the Greenland ice sheet, as well as changes in cryosphere elements such as the Antarctic ice sheet, sea ice, polynya and others, can significantly affect the strength of deep water convection and thereby the ocean thermohaline circulation. Assessment of cryospheric impact on sea level change still has great uncertainty. Ignoring the impact of changes in land water storage, the contributions to sea level rise of thermal expansion by ocean warming and the cryosphere are nearly the same since industrialization, and the projected contribution of the cryosphere will exceed that of thermal expansion to sea level rise.