The atmospheric boundary layer and surface conditions during katabatic wind events over the Terra Nova Bay Polynya.

Wenta, Marta; Cassano, John J.

doi:10.1002/essoar.10503391.1

Cited by 5 publications

(11 citation statements)

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“…This study is an analysis of the thermodynamic and dynamic forcing that occurred within the katabatic wind jet over the TNBP. Although this study focuses solely on this one case, it was similar to the two other polynya transect cases performed during PIPERS (results not shown), the September 19, 2012 case from Wenta and Cassano (2020), and the cases described by Parish and Bromwich (1989), and was likely to have had many of the same characteristics as the lower atmosphere in other ACP situations. Following this introduction, Section 2 describes the theory and methods used to perform the thermodynamic analyses.…”

Section: Introductionsupporting

confidence: 56%

“…Further evidence suggesting sea spray enhancement of SHF in over ACPs comes from the September 19, 2012 case by Wenta and Cassano (2020). Although they did not publish any SHF estimates, the values displayed in their Figure 7 can be used to estimate SHF using the integral method, Equation , and ignoring radiation, entrainment and snow effects.…”

Section: Summary Conclusion and Discussionmentioning

confidence: 96%

“…Previous studies have demonstrated the importance of synoptic forcing in the regions of katabatic wind jets (e.g., Knuth & Cassano, 2011; Parish & Bromwich, 1987), including the TNB (Parish & Cassano, 2003a, 2003b; Wenta & Cassano, 2020). However the results from this case indicated that any pressure gradients resulting from synoptic events were weak and the airflow was dominated by local forcing.…”

Section: Summary Conclusion and Discussionmentioning

confidence: 99%

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Inside Katabatic Winds Over the Terra Nova Bay Polynya: 2. Dynamic and Thermodynamic Analyses

Guest

2021

JGR Atmospheres

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Antarctic coastal polynyas (ACPs) occur where air is funneled into valleys and ejected horizontally over adjacent ocean regions, pushing any newly formed sea ice away from the coast. During cold seasons, the exposure of the relatively warm ocean surfaces to the sometimes hurricane-force winds causes great amounts of enthalpy (sensible and latent heat energy) to be lost from the surface of the polynyas, resulting in sea ice formation (e.g., Gordon & Comiso, 1988;Z. Zhang et al., 2015), and brine rejection (Mathiot et al., 2012) which can lead to the creation of deep ocean water masses that circulate throughout the world ocean (Orsi & Wiederwohl, 2009;Rusciano et al., 2013). Although the surface areas of ACPs are relatively small (e.g., Bromwich & Kurtz, 1984), their potential impacts on regional and global climate are significant due to the large amounts of sea ice and dense water that are created within them (Fusco et al., 2009;Gordon, 2001) and the injection of heat and moisture into the atmosphere (Renfrew, 2002).Due to their small size, ACPs are not resolvable by the general circulation models (GCMs) that are used to understand and predict future climate change. Therefore, to quantify the potential impacts of ACPs on global climate and regional ice production, their enthalpy loss and related effects must be simulated using sub-grid scale parameterizations. Typically, these parameterizations of surface fluxes are based on bulk

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Section: Introductionsupporting

confidence: 56%

Section: Summary Conclusion and Discussionmentioning

confidence: 96%

Section: Summary Conclusion and Discussionmentioning

confidence: 99%

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Inside Katabatic Winds Over the Terra Nova Bay Polynya: 2. Dynamic and Thermodynamic Analyses

Guest

2021

JGR Atmospheres

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“…To judge how representative this case was, it was compared other known similar in situ measurements, in particular, the 19 September downwind transect case from Wenta and Cassano (2020), hereafter referred to as W&C, and also the two other TNB transects performed during the PIPERS cruise on May 1, 2017 and May 5, 2017 (“1May’ and “5May”), all of which shared many similarities. For all four transects, at all downwind locations, there were low level jets with cores occurring between 150 and 300 m elevation and enhanced wind speeds occurring up to ∼700 m elevation.…”

Section: Discussionmentioning

confidence: 99%

“…The biggest challenge is accurately representing the surface conditions, in particular the surface temperature of the sea ice and exposed ocean T sfc , which is highly variable in ACP regions. For example, Wenta and Cassano (2020) showed that AMPS had errors in the low‐level atmospheric structure predictions due to incorrect T sfc calculations. Another challenge for numerical simulations of ACPs is the representation of a variety of microphysical processes such sea spray production, sea spray freezing and sea ice formation, all of which can potentially have major impacts on the surface fluxes.…”

Section: Introductionmentioning

confidence: 99%

Inside Katabatic Winds Over the Terra Nova Bay Polynya: 1. Atmospheric Jet and Surface Conditions

Guest

2021

JGR Atmospheres

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Katabatic winds are a common feature of the Antarctic coastline (King & Turner, 1997;Parish & Bromwich, 1987). Longwave radiation from the Antarctic ice sheet cools the snow surface and removes heat from the near-surface air, creating ubiquitous, strong, low-level temperature inversions (Connolley, 1996). The shallow cold air flows downhill and is funneled into coastal valleys, where the sloping terrain allows the air parcels to gain momentum from gravity. In many situations, particularly on the East Antarctic Coast, the katabatic winds peter out quickly beyond the generating slopes due to surface friction, gravity wave dispersion (Renfrew, 2004;Vignon et al., 2020), opposing thermal winds from the build-up of cold air at the slope bottom (Vihma et al., 2011), opposing synoptic forcing (Seefeldt et al., 2007), or entrainment from above the jet (Manins & Sawford, 1979). In some situations, the synoptic pressure gradient forcing is favorable (downstream) or weak (Bromwich et al., 1990;Seefeldt & Cassano, 2012;Seefeldt et al., 2007) or the winds are decoupled from the surface (Andreas et al., 2000) and katabatic winds are able to propagate hundreds of kilometers across flat ice shelves and ocean surfaces.The Antarctic katabatic winds have been the source of considerable attention from the time of the first explorers due to their major impacts on navigation, visibility and human survival. The katabatic winds often form strong jets that are characterized by low-level, high-wind-speed cores that are surrounded by regions of strong vertical and horizontal wind shears. Katabatic jumps, or rapid increases in wind speed associated with the onset of a katabatic wind event (Ball, 1956), are common phenomena in many Antarctic coastal regions (e.g., Vignon et al., 2020). Katabatic winds can extend over the ocean and trigger mesoscale cyclones and other atmospheric features that affect regions far from the initial katabatic wind source (Bromwich,

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A Local Similarity Function for Katabatic Flows Derived From Field Observations Over Steep‐ and Shallow‐Angled Slopes

Hang

Oldroyd

Giometto

et al. 2021

Geophysical Research Letters

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Katabatic flow initiates over sloping terrain under a stably stratified atmosphere due to the surface radiative cooling. As the surface temperature cools, air near the ground becomes negatively buoyant with respect to air farther away from the slope at the same elevation and starts descending down the slope. The ambient environment and surface friction impose a drag force near the surface, thus causing a jet-like wind profile. Such flows are ubiquitous in nature over sloping mountainous terrains (Whiteman, 2000).Katabatic flows have a wide range of applications across different spatial and temporal scales. Over stably stratified mountainous terrain, such flows strongly affect the turbulent transport of momentum and scalars (Denby &

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The atmospheric boundary layer and surface conditions during katabatic wind events over the Terra Nova Bay Polynya.

Cited by 5 publications

References 0 publications

Inside Katabatic Winds Over the Terra Nova Bay Polynya: 2. Dynamic and Thermodynamic Analyses

Inside Katabatic Winds Over the Terra Nova Bay Polynya: 2. Dynamic and Thermodynamic Analyses

Inside Katabatic Winds Over the Terra Nova Bay Polynya: 1. Atmospheric Jet and Surface Conditions

A Local Similarity Function for Katabatic Flows Derived From Field Observations Over Steep‐ and Shallow‐Angled Slopes

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