An Overview of the Vertical Structure of the Atmospheric Boundary Layer in the Central Arctic during MOSAiC
Abstract. Observations collected during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) provide an annual cycle of the vertical thermodynamic and kinematic structure of the atmospheric boundary layer (ABL) in the central Arctic. A self-organizing map (SOM) analysis conducted using radiosonde observations shows a range in the Arctic ABL vertical structure from very shallow and stable, with a strong surface-based virtual potential temperature (θv) inversion, to deep and near-neutral, with a weak elevated θv inversion. Profile observations from the DataHawk2 uncrewed aircraft system between 23 March and 26 July 2020 largely sampled the same profile structures, which can be further analyzed to provide unique insight into the turbulent characteristics of the ABL. The patterns identified by the SOM allowed for the derivation of criteria to categorize stability within and just above the ABL, which reveals that the Arctic ABL is stable and near-neutral with similar frequencies. In conjunction with observations from additional measurement platforms, including a 10 m meteorological tower, ceilometer, and microwave radiometer, the radiosonde observations provide insight into the relationships between atmospheric stability and a variety of atmospheric thermodynamic and kinematic features. The average ABL height was found to be 150 m, and ABL height increases with decreasing stability. A low-level jet was observed in 76 % of the radiosondes, with an average height of 401 m and an average speed of 11.5 m s−1. At least one temperature inversion below 5 km was observed in 99.7 % of the radiosondes, with an average base height of 260 m and an average intensity of 4.8 °C. The only cases without a temperature inversion were those with weak stability aloft. Clouds were observed within the 30 minutes preceding radiosonde launch 64 % of the time. These were typically low clouds, and high clouds largely coincide with a stable ABL. The amount of atmospheric moisture present increases with decreasing stability.
Gina C. Jozef et al.
Status: open (until 23 Jun 2023)
- CC1: 'Comment on egusphere-2023-780', Günther Heinemann, 13 May 2023 reply
- CC2: 'Comment on egusphere-2023-780', Günther Heinemann, 19 May 2023 reply
Gina C. Jozef et al.
Initial radiosonde data from 2019-10 to 2020-09 during project MOSAiC, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven https://doi.org/10.1594/PANGAEA.928656
DataHawk2 Uncrewed Aircraft System data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign, B1 level https://doi.org/10.18739/A2KH0F08V
Met City meteorological and surface flux measurements (Level 3, final), Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC), central Arctic, October 2019 – September 2020 https://doi.org/10.18739/A2PV6B83F
Ceilometer (CEIL). 2019-10-11 to 2020-10-01, ARM Mobile Facility (MOS) MOSAIC (Drifting Obs - Study of Arctic Climate); AMF2 (M1) http://dx.doi.org/10.5439/1181954
MWR Retrievals (MWRRET1LILJCLOU). 2019-10-11 to 2020-10-01, ARM Mobile Facility (MOS) MOSAIC (Drifting Obs - Study of Arctic Climate); AMF2 (M1) http://dx.doi.org/10.5439/1027369
Gina C. Jozef et al.
Viewed (geographical distribution)
The fraction of LLJ profiles of 76% is very high and exceeds the values found by previous studies for sea ice in polar regions. Lopez-Garcia et al. (2022) found about 50% of the cases using the same radiosonde data set, but only 6-hourly ascents. Tuononen et al. (2015) found about 20% as a model-based climatology for the inner Arctic.
The method of LLJ detection needs more explanation. How do you treat multiple maxima? Do you just search for the next minimum about the LLJ height or any minimum below 1500m? Do you apply a low-pass filter on the radiosonde data to remove turbulent bursts (which was the motivation of Tuononen et al. (2015) to use a 25% criterion)? Have you made any consistency checks, if you have jumps in LLJ height between consecutive profiles? This should be tested for periods with 3-hourly radiosonde profiles.
It should be proved that turbulent bursts do not influence the results. The evaluation should be repeated using the 25% criterion and/or a filtering. The differences particularly to the results of Tuononen et al. (2015) should be discussed.