Abstract
In 2014/2015 a one-year field campaign at the Tiksi observatory in the Laptev Sea area was carried out using Sound Detection and Ranging/Radio Acoustic Sounding System (SODAR/RASS) measurements to investigate the atmospheric boundary layer (ABL) with a focus on low-level jets (LLJ) during the winter season. In addition to SODAR/RASS-derived vertical profiles of temperature, wind speed and direction, a suite of complementary measurements at the Tiksi observatory was available. Data of a regional atmospheric model were used to put the local data into the synoptic context. Two case studies of LLJ events are presented. The statistics of LLJs for six months show that in about 23% of all profiles LLJs were present with a mean jet speed and height of about 7 m/s and 240 m, respectively. In 3.4% of all profiles LLJs exceeding 10 m/s occurred. The main driving mechanism for LLJs seems to be the baroclinicity, since no inertial oscillations were found. LLJs with heights below 200 m are likely influenced by local topography.
Highlights
Measurements of the cross-path wind speed of the BLS were used to check the plausibility of the lowest-level Sound Detection and Ranging (SODAR) winds, but since we focus on level jets (LLJ) and inversions, further results from the scintillometer are not presented in this paper
During the first two days, strong winds are present above 400 m, but the range of the SODAR does not allow to detect these as LLJs
We focus on the LLJ
Summary
The representation of processes of the atmospheric boundary layer (ABL) in polar regions is still a major challenge for weather forecast and climate models. The polar regions are often regarded as a natural laboratory for investigating ABL processes [5] This is the case for the SBL during winter, since there is no or only little solar radiation and no daily course. Apart from LLJs, there are several important phenomena in the SBL, such as surface and elevated inversions or fog, which influence the whole boundary layer. These phenomena can be best studied with a combination of high-resolution ground-based remote sensing systems, tower measurements, and radio soundings. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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