Terrestrial Evaporation and Global Climate: Lessons from Northland, a Planet with a Hemispheric Continent
Terrestrial Evaporation and Global Climate: Lessons from Northland, a Planet with a Hemispheric Continent
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DOI：
10.1175/jcli-d-20-0452.1
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发表时间：
2021-03-01
影响因子：
4.9
通讯作者：
Battisti, David S.
中科院分区：
文献类型：
--
作者：
Lague, Marysa M.;Pietschnig, Marianne;Battisti, David S.
受地球上陆地分布半球不对称的启发，我们探索了北国的气候，这是一个高度理想化的星球，拥有北半球大陆和南半球海洋。北国的气候可分为四个不同的区域：南半球海洋、季节性潮湿的热带地区、中纬度沙漠和北方大沼泽。我们评估改变北部地区的地表特性如何驱动温度、降水模式、全球能源预算和大气动态的变化。我们观察到对陆地表面蒸发变化的令人惊讶的反应，抑制北部地区的陆地蒸发会使陆地和海洋变冷。在之前的研究中，发现抑制陆地蒸发会减少地表的潜冷，从而导致局部变暖。然而，减少蒸发也会减少大气中的水蒸气，从而降低温室效应的强度并导致大规模降温。我们使用一组理想化的气候模型模拟来表明，抑制北半球不同大小大陆的陆地蒸发可能会导致陆地表面变暖或变冷，具体取决于哪种竞争效应占主导地位。我们发现，陆地总面积和连续大陆大小的结合控制着潜热通量减少造成的局部变暖与大气水蒸气减少造成的大规模冷却之间的平衡。最后，我们演示了陆地热容量、反照率和蒸发如何调节大陆和海洋上空 ITCZ 的位置。
Motivated by the hemispheric asymmetry of land distribution on Earth, we explore the climate of Northland, a highly idealized planet with a Northern Hemisphere continent and a Southern Hemisphere ocean. The climate of Northland can be separated into four distinct regions: the Southern Hemisphere ocean, the seasonally wet tropics, the midlatitude desert, and the Great Northern Swamp. We evaluate how modifying land surface properties on Northland drives changes in temperatures, precipitation patterns, the global energy budget, and atmospheric dynamics. We observe a surprising response to changes in land surface evaporation, where suppressing terrestrial evaporation in Northland cools both land and ocean. In previous studies, suppressing terrestrial evaporation has been found to lead to local warming by reducing latent cooling of the land surface. However, reduced evaporation can also decrease atmospheric water vapor, reducing the strength of the greenhouse effect and leading to large-scale cooling. We use a set of idealized climate model simulations to show that suppressing terrestrial evaporation over Northern Hemisphere continents of varying size can lead to either warming or cooling of the land surface, depending on which of these competing effects dominates. We find that a combination of total land area and contiguous continent size controls the balance between local warming from reduced latent heat flux and large-scale cooling from reduced atmospheric water vapor. Finally, we demonstrate how terrestrial heat capacity, albedo, and evaporation all modulate the location of the ITCZ both over the continent and over the ocean.