Application of remotely piloted aircraft systems in observing the atmospheric boundary layer over Antarctic sea ice in winter

Abstract Regional simulations of the atmospheric boundary layer over Antarctic sea ice that have been adequately validated are rare. To address this gap, the authors use the doubly nested Polar Weather Research and Forecasting (Polar WRF) mesoscale model to simulate conditions during Ice Station Weddell (ISW) in the austral autumn and winter of 1992. The WRF simulations test two boundary layer schemes: Mellor–Yamada–Janjic and the Asymmetric Convective Model. Validation is against surface-layer and sounding observations from ISW. Simulated latent and sensible heat fluxes for both boundary layer schemes had poor correlation with the observed fluxes. Simulated surface temperature had better correlation with the observations, with a typical bias of 0–2 K and a root-mean-square error of 6–7 K. For surface temperature and wind speed, the Polar WRF yielded better results than the ECMWF Re-Analysis Interim (ERA-Interim). A more challenging test of the simulations is to reproduce features of the low-level jet and the temperature inversion, which were observed, respectively, in 80% and 96% of the ISW radiosoundings. Both boundary layer schemes produce only about half as many jets as were observed. Moreover, the simulated jet coincided with an observed jet only about 30% of the time. The number of temperature inversions and the height at the inversion base were better reproduced, although this was not the case with the depth of the inversion layer. Simulations of the temperature inversion improved when forecasts of cloud fraction agreed to within 0.3 with observations. The modeled inversions were strongest when the incoming longwave radiation was smallest, but this relationship was not observed at ISW.

Download Full-text

Observations of the thermodynamic and kinematic state of the atmospheric boundary layer over the San Luis Valley, CO using remotely piloted aircraft systems during the LAPSE-RATE field campaign

10.5194/essd-2020-194 ◽

2020 ◽

Author(s):

Elizabeth A. Pillar-Little ◽

Brian R. Greene ◽

Francesca M. Lappin ◽

Tyler M. Bell ◽

Antonio R. Segales ◽

...

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Complex Terrain ◽

Lapse Rate ◽

San Luis Valley ◽

Aircraft Systems ◽

University Of Oklahoma ◽

San Luis ◽

Remotely Piloted Aircraft ◽

Convection Initiation

Abstract. In July 2018, the University of Oklahoma deployed three CopterSonde 2 remotely piloted aircraft systems (RPAS) to take measurements of the evolving thermodynamic and kinematic state of the atmospheric boundary layer (ABL) over complex terrain in the San Luis Valley, Colorado. A total of 180 flights were completed over five days, with teams operating simultaneously at two different sites in the northern half of the valley. Two days of operations focused on convection initiation studies, one day focused on ABL diurnal transition studies, one day focused on internal comparison flights, and the last day of operations focused on cold air drainage flows. The data from these coordinated flights provides insight into the horizontal heterogeneity of the atmospheric state over complex terrain as well as the expected horizontal footprint of RPAS profiles. This dataset, along with others collected by other universities and institutions as a part of the LAPSE-RATE campaign, have been submitted to Zenodo (Greene et al., 2020) for free and open access (https://doi.org/10.5281/zenodo.3737087).

Download Full-text

Interactions Between Arctic Sea Ice and Atmospheric Boundary Layer in the Presence of Leads

10.21236/ada281961 ◽

1993 ◽

Author(s):

Judith A. Curry

Keyword(s):

Boundary Layer ◽

Sea Ice ◽

Atmospheric Boundary Layer ◽

Arctic Sea Ice ◽

Arctic Sea

Download Full-text

Observations and Modelling of the Atmospheric Boundary Layer Over Sea-Ice in a Svalbard Fjord

Boundary-Layer Meteorology ◽

10.1007/s10546-011-9609-1 ◽

2011 ◽

Vol 140 (1) ◽

pp. 105-123 ◽

Cited By ~ 21

Author(s):

Eeva Mäkiranta ◽

Timo Vihma ◽

Anna Sjöblom ◽

Esa-Matti Tastula

Keyword(s):

Boundary Layer ◽

Sea Ice ◽

Atmospheric Boundary Layer

Download Full-text

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;

Download Full-text

Area-Averaged Surface Moisture Flux over Fragmented Sea Ice: Floe Size Distribution Effects and the Associated Convection Structure within the Atmospheric Boundary Layer

Atmosphere ◽

10.3390/atmos10110654 ◽

2019 ◽

Vol 10 (11) ◽

pp. 654

Author(s):

Marta Wenta ◽

Agnieszka Herman

Keyword(s):

Boundary Layer ◽

Sea Ice ◽

Atmospheric Boundary Layer ◽

Weather Prediction ◽

Moisture Flux ◽

Spatial Arrangement ◽

Weather Research And Forecasting ◽

Sea Ice Concentration ◽

Surface Moisture ◽

Ice Concentration

Sea ice fragmentation results in the transformation of the surface from relatively homogeneous to highly heterogeneous. Atmospheric boundary layer (ABL) rapidly responds to those changes through a range of processes which are poorly understood and not parametrized in numerical weather prediction (NWP) models. The aim of this work is to increase our understanding and develop parametrization of the ABL response to different floe size distributions (FSD). The analysis is based on the results of simulations with the Weather Research and Forecasting model. Results show that FSD determines the distribution and intensity of convection within the ABL through its influence on the atmospheric circulation. Substantial differences between various FSDs are found in the analysis of spatial arrangement and strength of ABL convection. To incorporate those sub-grid effects in the NWP models, a correction factor for the calculation of surface moisture heat flux is developed. It is expressed as a function of floe size, sea ice concentration and wind speed, and enables a correction of the flux computed from area-averaged quantities, as is typically done in NWP models. In general, the presented study sheds some more light on the sea ice–atmosphere interactions and provides the first attempt to parametrize the influence of FSD on the ABL.

Download Full-text

Two fast temperature sensors for probing of the Atmospheric Boundary Layer using small Remotely Piloted Aircraft (RPA)

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-3089-2013 ◽

2013 ◽

Vol 6 (2) ◽

pp. 3089-3127

Author(s):

N. Wildmann ◽

M. Mauz ◽

J. Bange

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Low Cost ◽

Measurement Range ◽

Temperature Sensors ◽

Resistance Thermometer ◽

Remotely Piloted Aircraft ◽

Measurement Principle ◽

Wire Resistance ◽

Radiation Error

Abstract. Two types of temperature sensors are designed and tested, a thermocouple and a fine wire resistance thermometer. The intention of this study is to figure out which kind of measurement principle is in general more suited for atmospheric boundary layer meteorology with small RPA. The sensors are calibrated in a NIST traceable climate chamber and validated in flight against tower measurements, radiosondes and remote sensing. The sensors have a measurement range of at least −10...50° C, an absolute RMS error of less than ±0.2 K which is stable over the lifetime of the sensors, and a resolution of about 0.01 K. Both devices are tested for typical errors like radiation error and adiabatic heating, as well as for their dynamic response. Spectral resolutions of up to approximately 10 Hz can be obtained with both sensors, which makes them suitable for turbulence measurements. Their low cost of less than 100 EUR in pure hardware is a major advantage for research with small RPA.

Download Full-text