Turbulent heat fluxes across the surface are an important mechanism of land-atmosphere coupling. But there is still a lack of sufficient observational measurements, particularly over the climate sensitive Tibetan Plateau (TP). This paper examines the partitioning between sensible and latent heat fluxes during growing season using the Bowen ratio as a diagnostic based on eddy covariance measurements from 12 observational sites located on the TP with the altitudes ranging between 3327 m and 4509 m above sea level. The results show an average Bowen ratio of 1.13, indicating that sensible heat flux is only slightly dominant in surface energy balance. For different climate zones, Bowen ratio varies from 0.56 to 1.05 in the semi-arid zone, 0.53 and 0.57 in the subhumid region, and 2.73 to 3.11 in the arid zone. The Bowen ratio shows sensitivity to soil dry and wet condition, with higher values during drier soil conditions. In the arid to semi-arid regions, the Bowen ratio shows a clear positive correlation with the Drought Soil Index (DSI) and a negative correlation with the Normalized Difference Vegetation Index (NDVI), suggesting sensitivity to soil moisture conditions. In the sub-humid climate zone, vapor pressure deficit (VPD) is the dominant factor influencing the Bowen ratio. In the wet and dry transition zone, soil moisture, VPD, NDVI and land-air temperature difference all have a role to play.

中文翻译：

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青藏高原局部生长季地表热通量分配观测


地表湍流热通量是陆地-大气耦合的重要机制。但仍然缺乏足够的观测测量，特别是在气候敏感的青藏高原（TP）。本文基于高原上海拔 3327 m 至 4509 m 的 12 个观测点的涡度协方差测量，使用鲍文比作为诊断，研究了生长季节感热通量和潜热通量之间的划分。结果显示平均鲍文比为 1.13，表明感热通量在表面能量平衡中仅略微占主导地位。对于不同的气候区，鲍文比在半干旱区为0.56至1.05，在半湿润区为0.53至0.57，在干旱区为2.73至3.11。鲍文比显示出对土壤干燥和潮湿条件的敏感性，在干燥的土壤条件下具有较高的值。在干旱半干旱地区，鲍文比与干旱土壤指数（DSI）呈明显正相关，与归一化植被指数（NDVI）呈负相关，表明其对土壤水分条件的敏感性。在半湿润气候区，水汽压差（VPD）是影响鲍文比的主导因素。在干湿过渡带，土壤湿度、VPD、NDVI和陆气温差都发挥着作用。