Case Study of Blowing Snow Impacts on the Antarctic Peninsula Lower Atmosphere and Surface Simulated with a Snow/ice Enhanced WRF Model

The synoptic origins of precipitation on the western side of the Antarctic Peninsula over the one year period March 1992 to February 1993 are investigated using meteorological observations, satellite imagery and analyses produced by the UK Meteorological Office. Precipitation at Rothera Station was found to occur at 30% of the synoptic reporting time with 80% of precipitation reports being associated with cyclonic disturbances. Although three quarters of all precipitation reports were for snow, the proximity of Rothera to the zone of maximum cyclonic activity meant that incursions of mild air produced rain in all seasons. During the year 95% of all precipitation was classed as slight. Variability of precipitation on the intraseasonal timescale was highly dependent on the synoptic-scale circulation. The most common synoptic situation for precipitation was a frontal cyclone over the Bellingshausen Sea which accounted for 38% of all precipitation events and 62% of the moderate and heavy precipitation reports. Of the extra-tropical cyclones that gave precipitation 49% were found to have developed south of 60°S. None of the precipitation at Rothera was attributable to mesocyclones. Snow stake measurements from Rothera were a poor indicator of precipitation as a result of blowing snow.

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High-Resolution Numerical Modelling of Near-Surface Atmospheric Fields in the Complex Terrain of James Ross Island, Antarctic Peninsula

Atmosphere ◽

10.3390/atmos12030360 ◽

2021 ◽

Vol 12 (3) ◽

pp. 360

Author(s):

Michael Matějka ◽

Kamil Láska ◽

Klára Jeklová ◽

Jiří Hošek

Keyword(s):

Wind Speed ◽

Air Temperature ◽

Antarctic Peninsula ◽

Wind Direction ◽

Wrf Model ◽

Lower Altitude ◽

Near Surface ◽

James Ross Island ◽

The Antarctic ◽

The Impact

The Antarctic Peninsula belongs to the regions of the Earth that have seen the highest increase in air temperature in the past few decades. The warming is reflected in degradation of the cryospheric system. The impact of climate variability and interactions between the atmosphere and the cryosphere can be studied using numerical atmospheric models. In this study, the standard version of the Weather Research and Forecasting (WRF) model was validated on James Ross Island in the northern part of the Antarctic Peninsula. The aim of this study was to verify the WRF model output at 700 m horizontal resolution using air temperature, wind speed and wind direction observations from automatic weather stations on the Ulu Peninsula, the northernmost part of James Ross Island. Validation was carried out for two contrasting periods (summer and winter) in 2019/2020 to assess possible seasonal effects on model accuracy. Simulated air temperatures were in very good agreement with measurements (mean bias −1.7 °C to 1.4 °C). The exception was a strong air temperature inversion during two of the winter days when a significant positive bias occurred at the coastal and lower-altitude locations on the Ulu Peninsula. Further analysis of the WRF estimates showed a good skill in simulating near-surface wind speed with higher correlation coefficients in winter (0.81–0.93) than in summer (0.41–0.59). However, bias and RMSE for wind speed tended to be better in summer. The performance of three WRF boundary layer schemes (MYJ, MYNN, QNSE) was further evaluated. The QNSE scheme was generally more accurate than MYNN and MYJ, but the differences were quite small and varied with time and place. The MYNN and QNSE schemes tended to achieve better wind speed simulation quality than the MYJ scheme. The model successfully captured wind direction, showing only slight differences to the observed values. It was shown that at lower altitudes the performance of the model can vary greatly with time. The model results were more accurate during high wind speed southwestern flow, while the accuracy decreased under weak synoptic-scale forcing, accompanied by an occurrence of mesoscale atmospheric processes.

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The Ocean Loading Effect in the GPS Analysis: A Case Study in the Antarctic Peninsula Region

Marine Geodesy ◽

10.1080/01490410116803 ◽

2001 ◽

Vol 24 (1) ◽

pp. 13-25

Author(s):

R. Dach, R. Dietrich

Keyword(s):

Antarctic Peninsula ◽

Loading Effect ◽

Ocean Loading ◽

Ocean Loading Effect ◽

The Antarctic

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Topographical effect of the Antarctic Peninsula on a strong wind event

Antarctic Science ◽

10.1017/s0954102021000444 ◽

2021 ◽

pp. 1-11

Author(s):

Hataek Kwon ◽

Seong-Joong Kim ◽

Sang-Woo Kim ◽

Sinu Kim

Keyword(s):

Wind Speed ◽

Antarctic Peninsula ◽

Critical Role ◽

Wrf Model ◽

Strong Discontinuity ◽

Strong Wind ◽

Easterly Wind ◽

Wind Event ◽

Topographical Effect ◽

The Antarctic

Abstract The topographical effect on a strong wind event that occurred on 7 January 2013 at King Sejong Station (KSJ), Antarctica, was investigated using the Polar Weather Research and Forecasting (WRF) model. Numerical experiments applying three different terrain heights of the Antarctic Peninsula (AP) were performed to quantitatively estimate the topographical effect on the selected strong wind event. The experiment employing original AP topography successfully represented the observed features in the strong wind event, both in terms of peak wind speed (by ~94%; ~19.7 m/s) and abrupt transitions of wind speed. In contrast, the experiment with a flattened terrain height significantly underestimated the peak wind speeds (by ~51%; ~10.4 m/s) of the observations. An absence of AP topography failed to simulate both a strong discontinuity of sea-level pressure fields around the east coast of the AP and a strong south-easterly wind over the AP. As a result, the observed downslope windstorm, driven by a flow overriding a barrier, was not formed at the western side of the AP, resulting in no further enhancement of the wind at KSJ. This result demonstrates that the topography of the AP played a critical role in driving the strong wind event at KSJ on 7 January 2013, accounting for ~50% of the total wind speed.

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