青藏高原及周边地区近地层小气候特征分析

利用中国气象局成都高原气象研究所建立的5个边界层站（湄潭、巴中、什邡、曲麻莱、狮泉河）2019年的观测资料，对比分析青藏高原及周边地区近地层大气要素变化和陆—气能量交换特征及异同点，探讨其原因。结果表明：（1）青藏高原及周边地区近地层大气温度、相对湿度、风速、感热通量、潜热通量、动量通量均符合一峰一谷的常规日变化特征，气压具有双峰双谷的日变化特征。（2）高海拔台站近地层温度日变幅（12℃）高于周边低海拔地区（4～6℃），季变幅与海拔高度的关系不显著。（3）相对湿度与温度关系密切，相对湿度的垂直结构和日变化都具有明显的区域差异，其垂直梯度夜间显著高于白天，峰值出现时间随夏、秋、春、冬季呈现季节性滞后，而谷值超前。（4）风速春季较大，夏、秋季次之，冬季小，季变幅略小于日变幅；低海拔区域的风速及其日变幅均显著低于高海拔区域。（5）低海拔区域气压季变幅（>13 hPa）远高于日变幅（2.5 hPa左右），而高海拔区域气压季变幅（>3 hPa）略低于日变幅（2 hPa左右）。（6）感热通量春季大、冬季小；感热通量和动量通量在高海拔区域均较高，二者具有较一致的日、季变化特征，表明大气动...

Observational Characteristics of Surface Layer Meteorological Elements over Tibetan Plateau and its Surrounding Area

Based on the observational data of five boundary layer stations in the Tibetan Plateau and its surrounding area in 2019, the characteristics and differences of atmospheric elements and energy exchange between land and air in this area are compared and analyzed, and the possible reasons are discussed. The main results are as follows: (1) The diurnal variation of air temperature, relative humidity, wind speed, sensible heat flux, latent heat flux and momentum flux over the Tibetan Plateau and its surrounding area shows the conventional characteristics of single peak and single valley, but atmospheric pressure appears the characteristics of double peaks and double valleys. (2) The daily variation amplitude of surface temperature near the high altitude station is much higher than that in the surrounding low altitude area, and the relationship between the seasonal variation and the altitude is not significant. (3) The vertical structure an daily variation characteristic of relative humidity have obvious regional differences, its daily variation amplitude is closely related to that of temperature, the vertical gradient of relative humidity at night is more significant than that in the daytime, and the time of peak value of relative humidity is seasonally delayed with summer, autumn, spring and winter, while the valley value is in advance. (4) The wind speed is higher in spring, followed by summer and autumn, and smaller in winter, the seasonal variation is slightly smaller than the daily variation. The wind speed and amplitude in the low altitude area are significantly lower than those in the high altitude area. (5) The seasonal variation of atmospheric pressure is much higher than the diurnal variation in the low altitude region, while the opposite is true in the high altitude region. (6) The sensible heat flux is affected by surface temperature difference, wind speed, relative humidity and net radiation, which is greater in spring than in winter; The sensible heat flux and momentum flux have the same diurnal/seasonal variation, and the atmospheric dynamic factor plays an important role in the sensible heat exchange between land and atmosphere, and both of them are higher at high altitude; The latent heat flux is higher in summer and lower in winter, and has no obvious relationship with the altitude, which is mainly determined by the location, temperature, humidity, topography, geomorphology and other factors.