Nocturnal jets in Skåne: an analysis of data from Hyltemossa research tower

Sammanfattning: A nocturnal jet is a low level air jet that is often seen at an altitude below 500 m during night time conditions. It can reach wind speeds of storm force and is thus of importance for aviation and also for transport of e.g. moisture and pollutants in the lower troposphere. By comparing wind speed measurements at 150 m at Hyltemossa research station (measured by ICOS Sweden) to the logarithmic wind profile and the power law wind profile for different times of the day and different time periods, no large deviations that could indicate a nocturnal jet were found. The temperature profile for the times where the largest deviations occurred where analysed and showed either that that the temperature inversions reached higher than 150 m, or in one case, that the lower most part of the troposphere was unstable. The analysis of the root mean square errors showed that the logarithmic wind profile described the lower troposphere better than the power law wind profile. However, both theories are based on simplifications of a complicated system