TY  - JOUR
A1  - Heinemann, Günther
A1  - Zentek, Rolf
T1  - A Model-Based Climatology of Low-Level Jets in the Weddell Sea Region of the Antarctic
T2  - Atmosphere
N2  - Low-level jets (LLJs) are climatological features in polar regions. It is well known that katabatic winds over the slopes of the Antarctic ice sheet are associated with strong LLJs. Barrier winds occurring, e.g., along the Antarctic Peninsula may also show LLJ structures. A few observational studies show that LLJs occur over sea ice regions. We present a model-based climatology of the wind field, of low-level inversions and of LLJs in the Weddell Sea region of the Antarctic for the period 2002–2016. The sensitivity of the LLJ detection on the selection of the wind speed maximum is investigated. The common criterion of an anomaly of at least 2 m/s is extended to a relative criterion of wind speed decrease above and below the LLJ. The frequencies of LLJs are sensitive to the choice of the relative criterion, i.e., if the value for the relative decrease exceeds 15%. The LLJs are evaluated with respect to the frequency distributions of height, speed, directional shear and stability for different regions. LLJs are most frequent in the katabatic wind regime over the ice sheet and in barrier wind regions. During winter, katabatic LLJs occur with frequencies of more than 70% in many areas. Katabatic LLJs show a narrow range of heights (mostly below 200 m) and speeds (typically 10–20 m/s), while LLJs over the sea ice cover a broad range of speeds and heights. LLJs are associated with surface inversions or low-level lifted inversions. LLJs in the katabatic wind and barrier wind regions can last several days during winter. The duration of LLJs is sensitive to the LLJ definition criteria. We propose to use only the absolute criterion for model studies.
KW  - Antarctic
KW  - katabatic winds
KW  - stable boundary layer
KW  - inversion
KW  - low-level jets
KW  - Weddellmeer
KW  - Strahlstrom
KW  - Katabatischer Wind
KW  - Inversion
KW  - Atmosphärische Grenzschicht
KW  - Modellierung
Y1  - 2021
UR  - https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/1858
UR  - https://nbn-resolving.org/urn:nbn:de:hbz:385-1-18587
VL  - 2021
IS  - Band 12 (2021)
PB  - MDPI
CY  - Basel
ER  -