Nature Climate Change ( IF 30.7 ) Pub Date : 2020-03-16 , DOI: 10.1038/s41558-020-0717-0 Giovanni Forzieri , Diego G. Miralles , Philippe Ciais , Ramdane Alkama , Youngryel Ryu , Gregory Duveiller , Ke Zhang , Eddy Robertson , Markus Kautz , Brecht Martens , Chongya Jiang , Almut Arneth , Goran Georgievski , Wei Li , Guido Ceccherini , Peter Anthoni , Peter Lawrence , Andy Wiltshire , Julia Pongratz , Shilong Piao , Stephen Sitch , Daniel S. Goll , Vivek K. Arora , Sebastian Lienert , Danica Lombardozzi , Etsushi Kato , Julia E. M. S. Nabel , Hanqin Tian , Pierre Friedlingstein , Alessandro Cescatti
Changes in vegetation structure are expected to influence the redistribution of heat and moisture; however, how variations in the leaf area index (LAI) affect this global energy partitioning is not yet quantified. Here, we estimate that a unit change in LAI leads to 3.66 ± 0.45 and −3.26 ± 0.41 W m−2 in latent (LE) and sensible (H) fluxes, respectively, over the 1982–2016 period. Analysis of an ensemble of data-driven products shows that these sensitivities increase by about 20% over the observational period, prominently in regions with a limited water supply, probably because of an increased transpiration/evaporation ratio. Global greening has caused a decrease in the Bowen ratio (B = H/LE) of −0.010 ± 0.002 per decade, which is attributable to the increased evaporative surface. Such a direct LAI effect on energy fluxes is largely modulated by plant functional types (PFTs) and background climate conditions. Land surface models (LSMs) misrepresent this vegetation control, possibly due to underestimation of the biophysical responses to changes in the water availability and poor representation of LAI dynamics.
中文翻译:
加强对全球陆地能量通量的植被控制
预计植被结构的变化会影响热量和水分的重新分配;但是,叶面积指数(LAI)的变化如何影响这种全局能量分配尚未确定。在这里,我们估计在1982-2016年期间,LAI的单位变化分别导致潜通量(LE)和感通量(H)分别为3.66±0.45和-3.26±0.41 W m -2。对一组数据驱动产品的分析表明,这些敏感性在观察期内增加了约20%,这在供水有限的地区尤为明显,这可能是由于蒸腾/蒸发比增加了。全球绿化导致博文比率降低(B = H/ LE)为每十年-0.010±0.002,这归因于蒸发表面的增加。LAI对能量通量的直接影响很大程度上受植物功能类型(PFT)和背景气候条件的调节。土地表面模型(LSMs)不能正确描述这种植被控制,这可能是由于对水利用量变化的生物物理响应估计不足,以及LAI动态表现不佳。