The vertical structure of the atmospheric boundary layer over the central Arctic Ocean

The tropopause height and the atmospheric boundary layer (PBL) height as well as the variation of inversion layer above the floating ice surface are presented using GPS (global position system) radiosonde sounding data and relevant data obtained by China's fourth arctic scientific expedition team over the central Arctic Ocean (86A degrees aEuro"88A degrees N, 144A degrees aEuro"170A degrees W) during the summer of 2010. The tropopause height is from 9.8 to 10.5 km, with a temperature range between -52.2 and -54.1A degrees C in the central Arctic Ocean. Two zones of maximum wind (over 12 m/s) are found in the wind profile, namely, low- and upper-level jets, located in the middle troposphere and the tropopause, respectively. The wind direction has a marked variation point in the two jets from the southeast to the southwest. The average PBL height determined by two methods is 341 and 453 mrespectively. These two methods can both be used when the inversion layer is very low, but the results vary significantly when the inversion layer is very high. A significant logarithmic relationship exists between the PBL height and the inversion intensity, with a correlation coefficient of 0.66, indicating that themore intense the temperature inversion is, the lower the boundary layer will be. The observation results obviously differ from those of the third arctic expedition zone (80A degrees aEuro"85A degrees N). The PBL height and the inversion layer thickness are much lower than those at 87A degrees aEuro"88A degrees N, but the inversion temperature is more intense, meaning a strong iceatmosphere interaction in the sea near the North Pole. The PBL structure is related to the weather system and the sea ice concentration, which affects the observation station.