Vertical Variation of Near Surface Temperature on the Northern Slope of Micang Mountain in the Western Bashan Mountain

Bashan Mountain is the division line between middle subtropical climate and northern subtropical climate in China.The further analysis and understanding of the vertical variation of near surface temperature under such complex terrain can provide foundation and basic data for climate change， ecological monitoring and ecological environment protection in this region.Based on the measured data of daily near surface temperature on the northern slope of Micang Mountain during 2013 -2019 from four automatic stations and 3 surrounding meteorological stations， which covers an elevation difference more than 1400 m， combined the sounding data at Hanzhong sounding station from 2017 to 2019， the lapse rates （γ） of near surface temperature and ambient atmospheric temperature were compared， and the vertical variation of near surface temperature on the north slope of Micang Mountain was analyzed， also its vertical climate zone is discussed.The results show that： （1） The near surface temperature decreases with the increasing altitude， its monthly average temperature reaches the highest and lowest in mid-July and January respectively.The average annual γ is 0.624±0.136 ℃·（100m）-1 during the observation period， close to that of free atmosphere.The average monthly γ is the smallest in December， increases gradually to August and then decreases， representing a distinct seasonal trend that steeper lapse rates occurred during warmer months， while shallower lapse rates occurred during colder months.The seasonal γ are 0.647±0.099， 0.732±0.103， 0.605± 0.113 and 0.508 ±0.120 ℃·（100m）-1 in the spring， summer， autumn and winter， respectively.The variation of maximum/minimum temperature is similar with that of average temperature， with an annual γ 0.646±0.185 and 0.606±0.166 ℃·（100m）-1 respectively.The average annual daily range has no obvious difference in each height， fluctuating between 7 ℃ and 10℃， and has no obvious linear relationship with the height.The annual range decreases linearly with the increasing height.（2） The decreasing trend of γ has changed since 2008， which has largely contributed to the narrowing of the radiation difference at areas between higher and lower， and the opposite vertical change trend of aerosols.（3） With the increase of height， the accumulated temperature of daily average temperature passed 0， 5 and 10 ℃ decreases linearly， and their γ is almost about 213 ℃·（100m）-1， their initial day delays and the final day advances， and the duration shortens， and decreases by 3.4， 6.1 and 7.0 d·（100m）-1， respectively.（4） The hierarchy of ambient air temperature changes with height is different clearly among 0.5~1.0 km， 1.0~2.5 km， 2.5~4.5 km and 4.5 km above， in where their temporal variation of air temperature γ is also significantly different， reflecting the comprehensively topographical impact of Qinghai-Xizang Plateau， Qinling Mountain， local Micang Mountain and surface on air temperature.The γ of monthly air temperature near the surface is slightly greater than that of ambient air temperature， which is similar with that of 0.5~1.0 km after May.（5） The vertical climate zone can be divided into northern subtropical zone， warm temperate zone and middle temperate zone， which are between 500~1000 meters， 1000~1500 meters and 1500~2500 meters respectively.