| The Arctic is of great significance to the global weather and climate system.However,due to the lack of intensive observations,the atmosphere of the Arctic has not been fully studied.This article uses China's 5th Arctic scientific expedition and high-resolution sounding data from Ny-(?)lesund station,and takes in-depth research on clouds and inversion in the Arctic region.Here we report on the characteristics of lower troposphere over the Arctic Ocean using high-resolution radiosonde data collected during the 5th Chinese National Arctic Research Expedition from July to September 2014.Statistical analyses show that temperature inversion(TI)occurred most frequently below 700 m,without apparent temporal variability between morning and noon.In contrast,the occurrence frequency of morning surface-based inversion(SBI)is always higher than at noon in the whole boundary layer,whereas the elevated inversion(EI)frequency seems much lower in the morning compared with that at noon.More frequent deeper clouds tend to occur in the morning than that at noon,which led to more frequent EI than SBI.SBI dominate in the clear-sky condition,whereas EI is generally observed under cloudy conditions.The study also found that sea level pressure(SLP),the stability of the lower troposphere(LTS),have a significant positive correlation with the intensity and thickness of the temperature inversion.Moreover,the weather-scale vortex system will reduce the intensity and thickness of the temperature inversion,and the high-pressure system will make the intensity and thickness of the temperature inversion stronger.At the same time,we also find that the black carbon transport in long-term space may also be one of the factors that affect the characteristics of the Arctic temperature inversion,which helps to enhance the temperature inversion.Based on the high-resolution(1s)radiosonde measurements from April 2017 to September2019 collected at the Ny-(?)lesund station in the Arctic,we analyz the characteristics of temperature inversion(TI)and clouds,including the diurnal and seasonal variabilities under different circulations.It is found that the clouds mainly appear in the lower troposphere,with the largest contribution by double-layer cloud.The seasonal variation of vertical cloud distribution above 7 km seems pronounced,which is closely linked to the seasonal variability of tropopause height.Besides,the diurnal variation of TI frequency exhibits significant seasonality,with a bimodal distribution in the vertical,with stronger TI intensity in summer.The lowest temperatures of elevated inversion top and bottom are observed in winter,whereas the lowest temperature of the surface-based inversion top is observed in spring,which may be related to the seasonal variation of sea surface temperature.The characteristics of cloud and TI are further analyzed under the five typical circulation patterns that are determined using the approach of the obliquely rotated principal component analysis in the T-mode.It is found that the influence of the weather system on low-level clouds is more obvious,while the impact of synoptic pattern on clouds in the upper troposphere seems negligible,likely due to the cold environment.The TI associated with cyclone systems tends to be much thinner and weaker,owning to the conditionally unstable conditions.This research aims to provide more understanding of the vertical structure of clouds and temperature inversions in the Arctic region through observations;and we hopes to provide references for cloud parameterization of numerical models... |
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