Sensitivity of land precipitation to surface evapotranspiration: a nonlocal perspective based on water vapor transport

The sensitivity of precipitation over land to surface evapotranspiration (ET) is among the most uncertain issues in land-atmosphere interactions. Past studies have mostly investigated this issue locally, and it remains a challenge to assess the nonlocal impacts. Here, we use a moisture tracking method and statistical analyses to quantify the sensitivity of precipitation to both local and nonlocal ET. It is found that, in a point-to-point sense, boreal summer precipitation is more sensitive to local ET than nonlocal ET for about 2/3 of land areas, while for about 1/5 land areas, precipitation is sensitive to ET of more than 1,000 km away. Remote sensitivities are generally an order of magnitude smaller than local sensitivities, but their combined effect could be large and useful, especially for regions without significant local sensitivities. Future studies of land-atmosphere interactions should be careful when making local assumptions.