Testing the efficacy of atmospheric boundary layer height detection algorithms using uncrewed aircraft system data from MOSAiC

Jozef, Gina; Cassano, John J.; Dahlke, Sandro; Boer, Gijs de

doi:10.5194/amt-15-4001-2022

Cited by 25 publications

(32 citation statements)

References 46 publications

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“…As the base of a TI is often located at or near the top of the ABL, and we also saw increasing ABL height with decreased stability, this makes sense. However, the large jump in TI altitude 585 for all regimes with weak stability aloft shows that TI altitude is not always the best method for determining ABL height, which agrees with Jozef et al (2022). This is further supported by the difference between TI base height and ABL height (Fig.…”

Section: Temperature Inversionsmentioning

confidence: 65%

“…ABL height from each radiosonde profile was determined using a bulk Richardson number (Rib) based approach in which the top of the ABL was identified as the first altitude in which Rib exceeds a critical value of 0.5 and remains 185 above the critical value for at least 20 consecutive meters (Jozef et al, 2022). The methodology for calculating the Rib profile used to identify ABL height follows that described in Jozef et al (2022) and Jozef et al (submitted). Once ABL height was identified, we determined the vertical gradient in virtual potential temperature (dθv/dz) and horizontal wind speed (dV/dz) between 35 m and the top of the ABL for each radiosonde.…”

Section: Deriving Quantities From Observational Datamentioning

confidence: 99%

“…To differentiate between stable cases (SS, MS, or WS) and near-neutral cases (NN), we use a threshold of 0.5 K (100 m) -1 , where if dθv/dz below 50 m is less than the threshold, it is considered NN, and if it is greater than or equal to the threshold, it is stable. This threshold was chosen, as it equates to the threshold of 0.2 K over 40 m used to discern a stable versus neutral ABL in Jozef et al (2022). Additional thresholds were derived to differentiate SS, MS, and WS.…”

mentioning

confidence: 99%

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An Overview of the Vertical Structure of the Atmospheric Boundary Layer in the Central Arctic during MOSAiC

Jozef

Cassano

Dahlke

et al. 2023

Preprint

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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.

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Section: Temperature Inversionsmentioning

confidence: 65%

Section: Deriving Quantities From Observational Datamentioning

confidence: 99%

mentioning

confidence: 99%

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An Overview of the Vertical Structure of the Atmospheric Boundary Layer in the Central Arctic during MOSAiC

Jozef

Cassano

Dahlke

et al. 2023

Preprint

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“…However, turbulence can still be present beyond Ri c (Sukoriansky et al, 2006), shown by a large number of meteorological and oceanographic observations (e.g., Kondo et al, 1978;Yagüe et al, 2001;Mack and Schoeberlein, 2004). Further, Jozef et al (2022a) found that a value of Ri g =0.5 to 0.75 on the vertical profile can be used to determine the ABL height based on DH2 MOSAiC data.…”

Section: Richardson Numbermentioning

confidence: 96%

Estimating turbulent energy flux vertical profiles from uncrewed aircraft system measurements: Exemplary results for the MOSAiC campaign

Egerer

Cassano

Shupe

et al. 2023

Preprint

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Abstract. This study analyzes turbulent energy fluxes in the Arctic atmospheric boundary layer (ABL) using measurements with a small Uncrewed Aircraft System (sUAS). Turbulent fluxes constitute a major part of the atmospheric energy budget and influence the surface heat balance by distributing energy vertically in the atmosphere. However, only few in-situ measurements exist of the vertical profile of turbulent fluxes in the Arctic ABL. The study presents a method to derive turbulent heat fluxes from DataHawk2 sUAS turbulence measurements, based on the flux gradient method with a parameterization of the turbulent exchange coefficient. This parameterization is derived from high-resolution horizontal wind speed measurements in combination with formulations for the turbulent Prandtl number and anisotropy depending on stability. Measurements were taken during the MOSAiC expedition in the Arctic sea ice during the melt season of 2020. For three example cases from this campaign, vertical profiles of turbulence parameters and turbulent heat fluxes are presented and compared to balloon-borne, radar and near-surface measurements. The combination of all measurements draws a consistent picture of ABL conditions and demonstrates the unique potential of the presented method for studying turbulent exchange processes in the vertical ABL profile with sUAS measurements.

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“…Indeed, the formation of HCl can serve as a sink for chlorine compounds in the troposphere, where HCl is taken up by aerosols and converted into Cl − , followed by an atmospheric deposition process 14,53 ; although, in the presence of NO x and reactive halogens (i.e., HOI and The reactions are based on the literatures 2,[12][13][14]64 . The mean boundary layer height was reported to vary between 100 and 200 m during the MOSAiC campaign 74,78 .…”

Section: Atmospheric Fate Of Hclo 3 and Hclomentioning

confidence: 99%

Widespread detection of chlorine oxyacids in the Arctic atmosphere

et al. 2023

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Chlorine radicals are strong atmospheric oxidants known to play an important role in the depletion of surface ozone and the degradation of methane in the Arctic troposphere. Initial oxidation processes of chlorine produce chlorine oxides, and it has been speculated that the final oxidation steps lead to the formation of chloric (HClO3) and perchloric (HClO4) acids, although these two species have not been detected in the atmosphere. Here, we present atmospheric observations of gas-phase HClO3 and HClO4. Significant levels of HClO3 were observed during springtime at Greenland (Villum Research Station), Ny-Ålesund research station and over the central Arctic Ocean, on-board research vessel Polarstern during the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) campaign, with estimated concentrations up to 7 × 106 molecule cm−3. The increase in HClO3, concomitantly with that in HClO4, was linked to the increase in bromine levels. These observations indicated that bromine chemistry enhances the formation of OClO, which is subsequently oxidized into HClO3 and HClO4 by hydroxyl radicals. HClO3 and HClO4 are not photoactive and therefore their loss through heterogeneous uptake on aerosol and snow surfaces can function as a previously missing atmospheric sink for reactive chlorine, thereby reducing the chlorine-driven oxidation capacity in the Arctic boundary layer. Our study reveals additional chlorine species in the atmosphere, providing further insights into atmospheric chlorine cycling in the polar environment.

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Testing the efficacy of atmospheric boundary layer height detection algorithms using uncrewed aircraft system data from MOSAiC

Cited by 25 publications

References 46 publications

An Overview of the Vertical Structure of the Atmospheric Boundary Layer in the Central Arctic during MOSAiC

An Overview of the Vertical Structure of the Atmospheric Boundary Layer in the Central Arctic during MOSAiC

Estimating turbulent energy flux vertical profiles from uncrewed aircraft system measurements: Exemplary results for the MOSAiC campaign

Widespread detection of chlorine oxyacids in the Arctic atmosphere

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