Atmospheric Dynamics Footprint on the January 2016 Ice Sheet Melting in West Antarctica

Hu, Xiaoming; Sejas, Sergio A.; Cai, Ming; Li, Zhenning; Yang, Song

doi:10.1029/2018gl081374

Cited by 14 publications

(8 citation statements)

References 29 publications

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“…Moreover, the recent work of Pollard et al (2015) and DeConto and Pollard (2016) indicates an important role for direct atmospheric forcing on ice shelf hydrofracturing in West Antarctica. Parameterizations for ice shelf hydrofracturing and the MICI in coupled climate models are still in their early stages; actual field data are required for model testing and refinement, and for attribution of surface melting events to specific atmospheric processes such as warm air intrusion (Nicolas and Bromwich 2011;Scott et al 2019), cloud all-wave surface radiation enhancement (Bennartz et al 2013;Hu et al 2019), or foehn winds (e.g., Elvidge et al 2015;Zou et al 2019).…”

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confidence: 99%

AWARE: The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment

Lubin

Zhang

Silber

et al. 2020

Bulletin of the American Meteorological Society

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The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) performed comprehensive meteorological and aerosol measurements and ground-based atmospheric remote sensing at two Antarctic stations using the most advanced instrumentation available. A suite of cloud research radars, lidars, spectral and broadband radiometers, aerosol chemical and microphysical sampling equipment, and meteorological instrumentation was deployed at McMurdo Station on Ross Island from December 2015 through December 2016. A smaller suite of radiometers and meteorological equipment, including radiosondes optimized for surface energy budget measurement, was deployed on the West Antarctic Ice Sheet between 4 December 2015 and 17 January 2016. AWARE provided Antarctic atmospheric data comparable to several well-instrumented high Arctic sites that have operated for many years and that reveal numerous contrasts with the Arctic in aerosol and cloud microphysical properties. These include persistent differences in liquid cloud occurrence, cloud height, and cloud thickness. Antarctic aerosol properties are also quite different from the Arctic in both seasonal cycle and composition, due to the continent’s isolation from lower latitudes by Southern Ocean storm tracks. Antarctic aerosol number and mass concentrations are not only non-negligible but perhaps play a more important role than previously recognized because of the higher sensitivities of clouds at the very low concentrations caused by the large-scale dynamical isolation. Antarctic aerosol chemical composition, particularly organic components, has implications for local cloud microphysics. The AWARE dataset, fully available online in the ARM Program data archive, offers numerous case studies for unique and rigorous evaluation of mixed-phase cloud parameterization in climate models.

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confidence: 99%

AWARE: The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment

Lubin

Zhang

Silber

et al. 2020

Bulletin of the American Meteorological Society

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“…Based on the SEB analysis of these four melt cases, the middle, western, and coastal RIS are more likely to have extensive melting due to an increase in LWD (up to 80 W⋅m −2 in anomaly), which is associated with direct moisture import from the Amundsen/Ross Sea or sublimation from the wet surface and above freezing surface temperatures (Figure 15a). Either the formation of the low-level liquid clouds or the deep warm air column causes the LWD to increase (Nicolas et al, 2017;Hu et al, 2019). This mechanism is observed in all four melt cases, while the 1991/1992 case is mainly driven by the direct warm air advection that leads to significant coastal melting (Zou et al, 2021).…”

Section: Discussionmentioning

confidence: 79%

“…The increase in LWD is also found along the coastal RIS, especially in the 1982/1983 and 1991/1992 cases. In brief, increasing LWD caused by the low-level liquid clouds and deep warm air column is usually responsible for the expansion of the surface melting over the coastal and middle RIS (Nicolas et al, 2017;Hu et al, 2019). Furthermore, sublimation from the melting surface favors cloud formation, as well as the melting expansion.…”

Section: Discussionmentioning

confidence: 99%

“…Nicolas et al (2017) suggest that the low-level liquid cloud contributed to surface melting expansion in the middle RIS via extensive LWD radiation. And Hu et al (2019) claim that a deep warm air column between 800 and 500 hPa also increases the LWD, which accounts for 60% of the increase in LWD. Similar to 10 January, SHF and LHF have less impact on SEB compared with SWD and LWD.…”

Section: Cloud Impacts On Sw Net and Lw Netmentioning

confidence: 99%

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Major surface melting over the Ross Ice Shelf part II: Surface energy balance

Zou

Bromwich

Montenegro

et al. 2021

Quart J Royal Meteoro Soc

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The West Antarctic climate is under the combined impact of synoptic and regional drivers. Regional factors have contributed to more frequent surface melting with a similar pattern recently, which accelerates ice loss and favors global sea‐level rise. Part I of this research identified and quantified the two leading drivers of Ross Ice Shelf (RIS) melting, viz. foehn effect and direct marine air advection, based on Polar WRF (PWRF) simulations. In this article (Part II), the impact of clouds and the pattern of surface energy balance (SEB) during melting are analyzed, as well as the relationship among these three factors. In general, net shortwave radiation dominates the surface melting with a daily mean value above 100 W·m−2. Foehn clearance and decreasing surface albedo respectively increase the downward shortwave radiation and increase the absorbed shortwave radiation, significantly contributing to surface melting in areas such as western Marie Byrd Land. Also, extensive downward longwave radiation caused by low‐level liquid cloud favors the melting expansion over the middle and coastal RIS. With significant moisture transport occurring over more than 40% of the time during the melting period, the impact from net radiation can be amplified. Moreover, frequent foehn cases can enhance the turbulent mixing on the leeside. With a Froude number (Fr) around 1 or slightly larger, fast downdrafts or reversed wind flows can let the warm foehn air penetrate down to the surface with up to 20 W·m−2 in sensible heat flux transfer to the ground. However, when the Froude number is close to infinity with breaking waves on the leeside, the contribution of turbulence to the surface warming is reduced. With better understanding of the regional factors for the surface melting, prediction of the future stability of West Antarctic ice shelves can be improved.

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“…After the ARs ceased, residual high water content clouds (Supplementary Figs. A.6e and A.6f) continued to enhance the downward longwave radiation and continued the melt event for another week(Hu et al [2019]). The high downward longwave radiation forcing was only partially compensated by a negative shortwave radiation ux at the surface (Supplementary Figs.…”

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confidence: 88%

Antarctic Atmospheric River Climatology and Impacts

Wille

2020

Preprint

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Atmospheric rivers, broadly defined as narrow yet long bands of strong horizontal vapor transport typically imbedded in a low level jet ahead of a cold front of an extratropical cyclone, provide a sub-tropical connection to the Antarctic continent and are observed to significantly impact the affected region&#8217;s surface mass balance over short, extreme events. When an atmospheric river makes landfall on the Antarctic continent, their signature is clearly observed in increased downward longwave radiation, cloud liquid water content, surface temperature, snowfall, surface melt, and moisture transport.Using an atmospheric river detection algorithm designed for Antarctica and regional climate simulations from MAR, we created a climatology of atmospheric river occurrence and their associated impacts on surface melt and snowfall. Despite their rarity of occurrence over Antarctica (maximum frequency of ~1.5% over a given point), they have produced significant impacts on melting and snowfall processes. From 1979-2017, atmospheric rivers landfalls and their associated radiative flux anomalies and foehn winds accounted for around 40% of the total summer surface melt on the Ross Ice Shelf (approaching 100% at higher elevations in Marie Byrd Land) and 40-80% of total winter surface melt on the ice shelves along the Antarctic Peninsula. On the other side of the continent in East Antarctica, atmospheric rivers have a greater influence on annual snowfall variability. There atmospheric rivers are responsible for 20-40% of annual snowfall with localized higher percentages across Dronning Maud Land, Amery Ice Shelf, and Wilkes Land.Atmospheric river landfalls occur within a highly amplified polar jet pattern and often are found in the entrance region of a blocking ridge. Therefore, atmospheric river variability is connected with atmospheric blocking variability over the Southern Ocean. There has been a significant increase in atmospheric river activity over the Amundsen-Bellingshausen sea and coastline and into Dronning Maud Land region from 1980-2018. Meanwhile, there is a significant decreasing trend in the region surrounding Law Dome. Our results suggest that atmospheric rivers play a significant role in the Antarctic surface mass balance, and that any future changes in atmospheric blocking or tropical-polar teleconnections may have significant impacts on future surface mass balance projections.

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Atmospheric Dynamics Footprint on the January 2016 Ice Sheet Melting in West Antarctica

Cited by 14 publications

References 29 publications

AWARE: The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment

AWARE: The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment

Major surface melting over the Ross Ice Shelf part II: Surface energy balance

Antarctic Atmospheric River Climatology and Impacts

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