Airborne Measurements in the Stable Boundary Layer over the Larsen Ice Shelf, Antarctica

King, John C.; Lachlan-Cope, Tom; Ladkin, R.; Weiss, Alexandra

doi:10.1007/s10546-008-9271-4

Cited by 45 publications

(64 citation statements)

References 28 publications

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“…On the other hand, the dry and warm air allows for significant sublimation, reflected in the SEB as a negative latent heat flux (−13.0 W m −2 ). This result is consistent with the anticorrelation of sensible and latent heat fluxes found over the Larsen Ice Shelf using airborne observations of the stable boundary layer (King et al, 2008). Overall, the increase of the shortwave and sensible heat fluxes outweighs the decrease of the longwave and latent heat fluxes.…”

Section: November 2010: Strong Westerlies and Intense Meltingsupporting

confidence: 89%

Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

et al. 2012

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Abstract. Data collected by two automatic weather stations (AWS) on the Larsen C ice shelf, Antarctica, between 22 January 2009 and 1 February 2011 are analyzed and used as input for a model that computes the surface energy budget (SEB), which includes melt energy. The two AWSs are separated by about 70 km in the north-south direction, and both the near-surface meteorology and the SEB show similarities, although small differences in all components (most notably the melt flux) can be seen. The impact of subsurface absorption of shortwave radiation on melt and snow temperature is significant, and discussed. In winter, longwave cooling of the surface is entirely compensated by a downward turbulent transport of sensible heat. In summer, the positive net radiative flux is compensated by melt, and quite frequently by upward turbulent diffusion of heat and moisture, leading to sublimation and weak convection over the ice shelf. The month of November 2010 is highlighted, when strong westerly flow over the Antarctic Peninsula led to a dry and warm föhn wind over the ice shelf, resulting in warm and sunny conditions. Under these conditions the increase in shortwave and sensible heat fluxes is larger than the decrease of net longwave and latent heat fluxes, providing energy for significant melt.

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Section: November 2010: Strong Westerlies and Intense Meltingsupporting

confidence: 89%

Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

et al. 2012

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“…The experimental studies of LLJs that accompany long-lived wintertime inversions over snow-covered surfaces are few. The LLJs over snow surfaces were studied in the Antarctic (Andreas et al 2000;Anderson 2003;King et al 2008) and in the Arctic (Vihma and Brümmer 2002;Brümmer and Thiemann 2002;Vihma et al 2005). The main parameters of LLJs obtained in the latter studies are similar to those of nocturnal summertime LLJs.…”

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confidence: 75%

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

Kallistratova

Kouznetsov

2011

Boundary-Layer Meteorol

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We evaluate the statistical properties of low-level jets (LLJs) observed by means of a network of Doppler sodars in the Moscow region, Russia. Continuous long-term measurements of the echo-signal intensity and wind-velocity profiles were carried out in July 2005 and in 2008-2010 synchronously in the centre of Moscow and at a rural site. The summertime nocturnal LLJs have a very clear diurnal cycle and exhibit features predicted by the Blackadar mechanism. In contrast, the long-lasting wintertime jets do not have any clear diurnal variability. The urban environment strongly influences LLJs in both seasons: above the city LLJs are higher, weaker and observed more rarely than at the rural site. In very cold periods (air temperature below −8 • C) no LLJs were observed over the city, instead convection emerged in the urban boundary layer. The results are based on observations made in

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“…The airborne measurements were collected using the British Antarctic Survey's Twin Otter MASIN research aircraft (King et al, 2008). A total of 24 flights (a total of 80 h) were performed during November and December 2015 from Halley.…”

Section: Campaign and Meteorological Overviewmentioning

confidence: 99%

In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

et al. 2017

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Abstract. During austral summer 2015, the Microphysics of Antarctic Clouds (MAC) field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change.The sampling was predominantly of stratus clouds, at temperatures between −20 and 0 • C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113 cm −3 and an interquartile range of 86 cm −3 . Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4 ± 2 µm near cloud base to 8 ± 3 µm near cloud top.Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000 m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than −10 • C, secondary ice production most likely through the Hallett-Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms.The concentration of large aerosols (diameters 0.5 to 1.6 µm) decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The dominant aerosol in the region was hygroscopic in nature, with the hygroscopicity parameter κ having a median value for the campaign of 0.66 (interquartile range of 0.38). This is consistent with other remote marine locations that are dominated by sea salt/sulfate.

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Airborne Measurements in the Stable Boundary Layer over the Larsen Ice Shelf, Antarctica

Abstract: These measurements provide insight into the processes that control surface melt rates in an area that has experienced recent rapid warming and deglaciation.

Cited by 45 publications

References 28 publications

Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

Low-Level Jets in the Moscow Region in Summer and Winter Observed with a Sodar Network

In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

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