Research On The Structural Characteristics Of Arctic Boundary Layer Inversion Temperature And Humidity Inversion Based On Radiosonde Data

The tropospheric temperature and humidity inversion structure is an important component of the Arctic climate system and is closely related to the exchange of moisture and heat between the surface and lower atmosphere,as well as to long-wave radiation and cloud formation.High-resolution sounding data from three Arctic stations(Global Climate Observing System Reference Upper-Air Network,GRUAN),conventional sounding data from 45 stations(Integrated Global Radiosonde Archive,IGRA),and the fifth generation reanalysis data of European Center for medium range weather forecasts(ECMWF)ERA5 are used to investigate the multi-layer temperature and humidity inversion structure in the Arctic,mainly including the analysis of characteristic changes,the situation of different influencing factors and the characteristics of the coexistence of temperature and humidity inversion.According to the different altitudes where the inversions occur,they are classified into surface-based inversion(SBI)and elevated inversion(EI),and surface-based humidity inversion(SBHI)and elevated humidity inversion(EHI).Through the study of three high-resolution representative stations,at the coastal stations,SBI is frequent throughout the year,and the first layer of elevated inversion(EI1)caused by warm advection,is thicker and stronger compared to those resulted from subsidence.The first layer of elevated humidity inversion(EHI1)tends to be formed by temperature inversion,while the second layer of elevated humidity inversion(EHI2)is mainly affected by water vapor advection.The coexistence of EI and EHI is more frequent in summer and less frequent in winter.The SBI,EI,SBHI and EHI coexist in the opposite way.The temperature and humidity inversion climatological characteristics obtained from 45 conventional radiosonde data are mainly found,SBI is more frequent,deeper,and stronger in winter and autumn than those in summer and spring.The peak value of EI frequency correlates well with the active anticyclone.The temporal and spatial variation of SBHI is similar to that of SBI.The frequency of SBI decreased in the Eastern Hemisphere and increased in the Western Hemisphere in the Arctic.The variation of Arctic SBI top height and strength has a significant decreasing trend in most areas.The spatial distribution of EI1 frequency trend is consistent with that of SBI.EI1 has the lower top height under warm advection.EHI1 are more frequent in summer and less frequent in winter under water vapor advection.The top height of EHI1 under water vapor advection is higher and weaker,while the top height is generally lower but stronger under the influence of temperature inversion.The simultaneous occurrence of EI and EHI enhances the intensity of temperature inversion and humidity inversion,and reduce the top height of temperature inversion and humidity inversion.