![]() Therefore, the land surface energy partitioning is closely related to climate variability. The energy partitioning that contains the information of land surface thermal-hydrologic properties further exerts influences on atmosphere by initially modifying boundary layer structure including the stability and height, which finally significantly affects atmospheric circulations, precipitation and climate on local, regional or larger scales 3, 4, 5, 6. For irrigation-dependent agricultural region, the ratio can even reach as low as 0.01 2. For instance, the Bowen ratio is found to be 0.61 during dry winter season but it reduces to 0.18 during summer monsoon season for cropland 1. Wetter land surface and larger vegetation fractions favor higher LHF and smaller SHF, resulting in a smaller Bowen ratio. Bowen ratio alone can reflect the relative magnitudes of SHF and LHF as well as the land surface thermal-hydrologic properties. The partitioning of land surface available energy is often described by the ratio of SHF to LHF, known as the Bowen ratio. Land surface conditions including soil moisture and green vegetation fractions significantly impact the land-atmosphere linkage by dominating the partitioning of land surface available energy into LHF and SHF. Therefore, they are critical parts of water and energy cycles, and govern the land-atmosphere interactions. Land surface heat fluxes, including latent heat flux (LHF) and sensible heat flux (SHF), link the land surface with the atmosphere by transporting land surface energy and moisture into the atmosphere. The intensifying LHF and precipitation indicate the acceleration of hydrological cycle in global terrestrial monsoon domains. Moreover, remarkable phase shifts in LHF and SHF are observed for monsoon domains during late-1990s, which are in phase with those of precipitation and monsoon strength. The increasing monsoon and precipitation on one hand favor more land surface available energy being converted into LHF on the other hand they enhance the LHF by increasing the land surface net radiation. Singular value decomposition (SVD) analyses show that monsoon strength explains 25.2% and 22.2% total covariance of LHF and SHF respectively in the first modes, and that precipitation slightly raises the percentages up to 27.8% and 24% respectively. The trends in LHF and SHF are closely linked to increasing global monsoon intensity and precipitation, especially for the monsoon domain that has annual precipitation lower than 1300 mm yr −1. Two other dominant trend patterns, (LHF−, SHF−) and (LHF+, SHF+), are observed in South African and South American monsoon domains, respectively. Moreover, the increasing rate of LHF was higher than the decreasing rate of SHF, which causes a decreased trend in Bowen ratio. During the past three decades, LHF and SHF have generally undergone a rising and decreasing trend (that is, (LHF+, SHF−)), respectively, in Asian, North African, Austrian, and South American monsoon domains. The climatology, trends and leading modes of land surface latent heat flux (LHF) and sensible heat flux (SHF) as well as their responses to monsoon and precipitation in global land monsoon domains are presented. ![]()
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