Early Spring

Interesting new bit of work by Dirmeyer and Brubaker in GRL about the effects of early spring on northern hemisphere water budgets:

Over most mid- and high-latitude areas, a strong annual cycle of recycling ratio exists; low during winter when storm tracks are active, tropospheric circulation strong, and surface evaporation rates low, high during summer when winds are light and evaporation is greater. Trends in recycling ratio have been found over large areas at high-latitudes that are consistent with an expansion into spring of the warm-season regime of water vapor recycling. These trends are consistent with observed vegetation-related changes often attributed to global climate change, and are most evident over northern Europe and North America where the density of meteorological data influencing the atmospheric analyses is high. Less extensive trends are found in other seasons.

Worth noting: their results are consistent with Aiguo Dai’s findings of increasing drought.