The Effect of Blowing Snow on Katabatic Winds in Antarctica

An acceleration of the katabatic winds during periods of blowing snow was observed in Adelie Land, Antarctica. Data collected by Automatic Weather Stations' (AWS) showed a change in the relationship between the katabatic term of the surface geostrophic wind (katabatic force) and the wind speed for periods of blowing snow. When measurements of the katabatic force were plotted against the cube of the wind speed, the slope was steeper for wind speeds at less than a threshold speed for blowing snow. The difference between these two slopes was partly explained by the effect of blowing snow entrained into the atmospheric boundary layer.

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Local Characteristics of the Nocturnal Boundary Layer in Response to External Pressure Forcing

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0011.1 ◽

2017 ◽

Vol 56 (11) ◽

pp. 3035-3047 ◽

Cited By ~ 17

Author(s):

Steven J. A. van der Linden ◽

Peter Baas ◽

J. Antoon van Hooft ◽

Ivo G. S. van Hooijdonk ◽

Fred C. Bosveld ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Stable Boundary Layer ◽

Dynamical Behavior ◽

Geostrophic Wind ◽

External Pressure ◽

Near Surface ◽

Stable Boundary ◽

Wind Speeds ◽

Turbulent Characteristics

AbstractGeostrophic wind speed data, derived from pressure observations, are used in combination with tower measurements to investigate the nocturnal stable boundary layer at Cabauw, the Netherlands. Since the geostrophic wind speed is not directly influenced by local nocturnal stability, it may be regarded as an external forcing parameter of the nocturnal stable boundary layer. This is in contrast to local parameters such as in situ wind speed, the Monin–Obukhov stability parameter (z/L), or the local Richardson number. To characterize the stable boundary layer, ensemble averages of clear-sky nights with similar geostrophic wind speeds are formed. In this manner, the mean dynamical behavior of near-surface turbulent characteristics and composite profiles of wind and temperature are systematically investigated. The classification is found to result in a gradual ordering of the diagnosed variables in terms of the geostrophic wind speed. In an ensemble sense the transition from the weakly stable to very stable boundary layer is more gradual than expected. Interestingly, for very weak geostrophic winds, turbulent activity is found to be negligibly small while the resulting boundary cooling stays finite. Realistic numerical simulations for those cases should therefore have a comprehensive description of other thermodynamic processes such as soil heat conduction and radiative transfer.

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Revisiting the Definition of the Drag Coefficient in the Marine Atmospheric Boundary Layer

Journal of Physical Oceanography ◽

10.1175/2010jpo4420.1 ◽

2010 ◽

Vol 40 (10) ◽

pp. 2325-2332 ◽

Cited By ~ 60

Author(s):

Richard J. Foreman ◽

Stefan Emeis

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Atmospheric Boundary Layer ◽

Drag Coefficient ◽

Friction Velocity ◽

Marine Boundary Layer ◽

Marine Atmospheric Boundary Layer ◽

Wind Speeds ◽

Traditional Definition ◽

Definition Of

Abstract A new functional form of the neutral drag coefficient for moderate to high wind speeds in the marine atmospheric boundary layer for a range of field measurements as reported in the literature is proposed. This new form is found to describe a wide variety of measurements recorded in the open ocean, coast, fetch-limited seas, and lakes, with almost one and the same set of parameters. This is the result of a reanalysis of the definition of the drag coefficient in the marine boundary layer, which finds that a constant is missing from the traditional definition of the drag coefficient. The constant arises because the neutral friction velocity over water surfaces is not directly proportional to the 10-m wind speed, a consequence of the transition to rough flow at low wind speeds. Within the rough flow regime, the neutral friction velocity is linearly dependent on the 10-m wind speed; consequently, within this rough regime, the new definition of the drag coefficient is not a function of the wind speed. The magnitude of the new definition of the neutral drag coefficient represents an upper limit to the magnitude of the traditional definition.

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Investigation of weather conditions and tropospheric BrO transport during Bromine Explosion Events in the Arctic and ozone depletion in Ny-Ålesund observed by satellite and ground-based remote sensing

10.5194/dach2022-73 ◽

2021 ◽

Author(s):

Bianca Zilker ◽

Anne-Marlene Blechschmidt ◽

Sora Seo ◽

Ilias Bougoudis ◽

Tim Bösch ◽

...

Keyword(s):

Boundary Layer ◽

Detection Limit ◽

Wind Speed ◽

Ozone Depletion ◽

Weather Conditions ◽

Tropospheric Chemistry ◽

The Arctic ◽

Blowing Snow ◽

High Wind ◽

Wind Speeds

Bromine Explosion Events (BEEs) have been observed since the late 1990s in the Arctic and Antarctic during polar spring and play an important role in tropospheric chemistry. In a heterogeneous, autocatalytic, chemical chain reaction cycle, inorganic bromine is released from the cryosphere into the troposphere and depletes ozone often to below detection limit. Ozone is a source of the most important tropospheric oxidizing agent OH and the oxidizing capacity and radiative forcing of the troposphere are thus being impacted. Bromine also reacts with gaseous mercury, thereby facilitating the deposition of toxic mercury, which has adverse environmental impacts. Cold saline surfaces, such as young sea ice, frost flowers, and snow are likely bromine sources during BEEs. Different meteorological conditions seem to favor the development of these events: on the one hand, low wind speeds and a stable boundary layer, where bromine can accumulate and deplete ozone, and on the other hand, high wind speeds above approximately 10 m/s with blowing snow and a higher unstable boundary layer. In high wind speed conditions &#8211; occurring for example along fronts of polar cyclones &#8211; recycling of bromine on snow and aerosol surfaces may take place aloft. To improve the understanding of weather conditions and bromine sources leading to the development of BEEs, case studies using high resolution S5P TROPOMI retrievals of tropospheric BrO together with meteorological simulations by the WRF model and Lagrangian transport simulations of BrO by FLEXPART-WRF are carried out. WRF simulations show, that high tropospheric BrO columns observed by TROPOMI often coincide with areas of high wind speeds. This probably points to release of bromine from blowing snow with cold temperatures favoring the bromine explosion reactions. However, some BrO plumes are observed over areas with very low wind speed and a stable low boundary layer. To monitor the amount of ozone depleted during a BEE, ozone sonde measurements from Ny-&#197;lesund are compared with MAX-DOAS BrO profiles. First evaluations show a drastic decrease in ozone, partly below the detection limit, while measuring enhanced BrO values at the same time. In order to analyze the possible origin of the BrO plume arriving in Ny-&#197;lesund, and to investigate its transportation route, FLEXPART-WRF runs are executed for the times of observed ozone depletion. &#160; This work was supported by the DFG funded Transregio-project TR 172 &#8220;Arctic Amplification (AC)3&#8220;.

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Variable Eddy Viscosities in the Atmospheric Boundary Layer from Ageostrophic Wind-Speed Profiles

Journal of Mathematical Fluid Mechanics ◽

10.1007/s00021-021-00575-1 ◽

2021 ◽

Vol 23 (2) ◽

Author(s):

Tony Lyons

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Atmospheric Boundary Layer ◽

Ageostrophic Wind

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Comparison of Large Eddy Simulations of a convective boundary layer with wind LIDAR measurements

Advances in Science and Research ◽

10.5194/asr-8-83-2012 ◽

2012 ◽

Vol 8 (1) ◽

pp. 83-86 ◽

Cited By ~ 5

Author(s):

J. G. Pedersen ◽

M. Kelly ◽

S.-E. Gryning ◽

R. Floors ◽

E. Batchvarova ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Geostrophic Wind ◽

Large Eddy Simulations ◽

Horizontal Wind ◽

Convective Boundary ◽

Horizontal Wind Speed ◽

Large Eddy ◽

Lidar Measurements ◽

Wind Lidar

Abstract. Vertical profiles of the horizontal wind speed and of the standard deviation of vertical wind speed from Large Eddy Simulations of a convective atmospheric boundary layer are compared to wind LIDAR measurements up to 1400 m. Fair agreement regarding both types of profiles is observed only when the simulated flow is driven by a both time- and height-dependent geostrophic wind and a time-dependent surface heat flux. This underlines the importance of mesoscale effects when the flow above the atmospheric surface layer is simulated with a computational fluid dynamics model.

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Stable Atmospheric Boundary Layers and Diurnal Cycles: Challenges for Weather and Climate Models

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-11-00187.1 ◽

2013 ◽

Vol 94 (11) ◽

pp. 1691-1706 ◽

Cited By ~ 245

Author(s):

A. A. M. Holtslag ◽

G. Svensson ◽

P. Baas ◽

S. Basu ◽

B. Beare ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Atmospheric Boundary Layer ◽

Climate Models ◽

Model Performance ◽

Weather Forecast ◽

The Arctic ◽

Diurnal Cycles ◽

Low Wind Speed ◽

Weather And Climate

The representation of the atmospheric boundary layer is an important part of weather and climate models and impacts many applications such as air quality and wind energy. Over the years, the performance in modeling 2-m temperature and 10-m wind speed has improved but errors are still significant. This is in particular the case under clear skies and low wind speed conditions at night as well as during winter in stably stratified conditions over land and ice. In this paper, the authors review these issues and provide an overview of the current understanding and model performance. Results from weather forecast and climate models are used to illustrate the state of the art as well as findings and recommendations from three intercomparison studies held within the Global Energy and Water Exchanges (GEWEX) Atmospheric Boundary Layer Study (GABLS). Within GABLS, the focus has been on the examination of the representation of the stable boundary layer and the diurnal cycle over land in clear-sky conditions. For this purpose, single-column versions of weather and climate models have been compared with observations, research models, and large-eddy simulations. The intercomparison cases are based on observations taken in the Arctic, Kansas, and Cabauw in the Netherlands. From these studies, we find that even for the noncloudy boundary layer important parameterization challenges remain.

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DETERMINATION OF WIND SHEAR AND TURBULENCE INTENSITY ACCORDING TO YAK42-D “ROSHYDROMET” RESEARCH AIRCRAFT DATA

Meteorologiya i Gidrologiya ◽

10.52002/0130-2906-2021-9-117-129 ◽

2021 ◽

pp. 117-129

Author(s):

V. V. VOLKOV ◽

◽

M. A. STRUNIN ◽

A. M. STRUNIN ◽

◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Wind Shear ◽

Vertical Shear ◽

Horizontal Shear ◽

S 100 ◽

Research Aircraft ◽

The Difference ◽

Wind Shears ◽

Aircraft Data

The results of the development and comparative analysis of methods for determining wind shear in the atmosphere (regression and difference ones) based on research aircraft data are presented. It is shown that shear calculation by the regression method gives the error of 0.002-0.006 (m/s)/km (depending on the length of the measurement sections) for horizontal shears and 0.04-0.12 (m/s)/100 m for vertical shears; the respective error of the difference method is 0.007 (m/s)/km and 0.07 (m/s)/100 m. Based on the Yak-42D “Roshydromet” research aircraft data, the values of shears of two horizontal components of wind speed in three directions (two horizontal and vertical) were calculated. According to the data of two research aircraft flights, the maximum values of the horizontal shear of wind speed components were reached above the boundary layer and were equal to 0.2 (m/s)/km, and the vertical shear was 1.2 (m/s)/100 m. The energy profiles of horizontal and vertical turbulent pulsations are constructed, it is shown that intense turbulence smooths wind shears in the convective atmospheric boundary layer.

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Evaluation of regional NWP results for sea ice covered Bothnia Bay (Baltic Sea) in winter 2020.

10.5194/egusphere-egu21-14612 ◽

2021 ◽

Author(s):

Marta Wenta ◽

Agnieszka Herman

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Sea Ice ◽

Surface Temperature ◽

Atmospheric Boundary Layer ◽

Baltic Sea ◽

Polar Regions ◽

Near Surface ◽

Accurate Representation ◽

Complex Processes

The ongoing development of NWP (Numerical Weather Prediction) models and their increasing horizontal resolution have significantly improved forecasting capabilities. However, in the polar regions models struggle with the representation of near-surface atmospheric properties and the vertical structure of the atmospheric boundary layer (ABL) over sea ice. Particularly difficult to resolve are near-surface temperature, wind speed, and humidity, along with diurnal changes of those properties. Many of the complex processes happening at the interface of sea ice and atmosphere, i.e. vertical fluxes, turbulence, atmosphere - surface coupling are poorly parameterized or not represented in the models at all. Limited data coverage and our poor understanding of the complex processes taking place in the polar ABL limit the development of suitable parametrizations. We try to contribute to the ongoing effort to improve the forecast skill in polar regions through the analysis of unmanned aerial vehicles (UAVs) and automatic weather station (AWS) atmospheric measurements from the coastal area of Bothnia Bay (Wenta et. al., 2021), and the application of those datasets for the analysis of regional NWP models' forecasts.&#160;Data collected during HAOS (Hailuoto Atmospheric Observations over Sea ice) campaign (Wenta et. al., 2021) is used for the evaluation of regional NWP models results from AROME (Applications of Research to Operations at Mesoscale) - Arctic, HIRLAM (High Resolution Limited Area Model) and WRF (Weather Research and Forecasting). The presented analysis focuses on 27 Feb. 2020 - 2 Mar. 2020, the time of the HAOS campaign, shortly after the formation of new, thin sea ice off the westernmost point of Hailuoto island.&#160; Throughout the studied period weather conditions changed from very cold (-14&#8451;), dry and cloud-free to warmer (~ -5&#8451;), more humid and opaquely cloudy. We evaluate models&#8217; ability to correctly resolve near-surface temperature, humidity, and wind speed, along with vertical changes of temperature and humidity over the sea ice. It is found that generally, models struggle with an accurate representation of surface-based temperature inversions, vertical variations of humidity, and temporal wind speed changes. Furthermore, a WRF Single Columng Model (SCM) is launched to study whether specific WRF planetary boundary layer parameterizations (MYJ, YSU, MYNN, QNSE), vertical resolution, and more accurate representation of surface conditions increase the WRF model&#8217;s ability to resolve the ABL above sea ice in the Bay of Bothnia. Experiments with WRF SCM are also used to determine the possible reasons behind model&#8217;s biases. Preliminary results show that accurate representation of sea ice conditions, including thickness, surface temperature, albedo, and snow coverage is crucial for increasing the quality of NWP models forecasts. We emphasize the importance of further development of parametrizations focusing on the processes at the sea ice-atmosphere interface.&#160;Reference:Wenta, M., Brus, D., Doulgeris, K., Vakkari, V., and Herman, A.: Winter atmospheric boundary layer observations over sea ice in the coastal zone of the Bay of Bothnia (Baltic Sea), Earth Syst. Sci. Data, 13, 33&#8211;42, https://doi.org/10.5194/essd-13-33-2021, 2021.&#160;

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Catch Characteristics of Precipitation Gauges in High-Latitude Regions with High Winds

Journal of Hydrometeorology ◽

10.1175/jhm542.1 ◽

2006 ◽

Vol 7 (5) ◽

pp. 984-994 ◽

Cited By ~ 21

Author(s):

Konosuke Sugiura ◽

Tetsuo Ohata ◽

Daqing Yang

Keyword(s):

Wind Speed ◽

High Latitude ◽

Cold Climate ◽

Strong Wind ◽

Blowing Snow ◽

High Wind ◽

Wind Speeds ◽

Solid Precipitation ◽

High Winds ◽

Correction Equations

Abstract Intercomparison of solid precipitation measurement at Barrow, Alaska, has been carried out to examine the catch characteristics of various precipitation gauges in high-latitude regions with high winds and to evaluate the applicability of the WMO precipitation correction procedures. Five manual precipitation gauges (Canadian Nipher, Hellmann, Russian Tretyakov, U.S. 8-in., and Wyoming gauges) and a double fence intercomparison reference (DFIR) as an international reference standard have been installed. The data collected in the last three winters indicates that the amount of solid precipitation is characteristically low, and the zero-catch frequency of the nonshielded gauges is considerably high, 60%–80% of precipitation occurrences. The zero catch in high-latitude high-wind regions becomes a significant fraction of the total precipitation. At low wind speeds, the catch characteristics of the gauges are roughly similar to the DFIR, although it is noteworthy that the daily catch ratios decreased more rapidly with increasing wind speed compared to the WMO correction equations. The dependency of the daily catch ratios on air temperature was confirmed, and the rapid decrease in the daily catch ratios is due to small snow particles caused by the cold climate. The daily catch ratio of the Wyoming gauge clearly shows wind-induced losses. In addition, the daily catch ratios are considerably scattered under strong wind conditions due to the influence of blowing snow. This result suggests that it is not appropriate to extrapolate the WMO correction equations for the shielded gauges in high-latitude regions for high wind speed of over 6 m s−1.

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