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

2020 ◽  
Author(s):  
Marta Aleksandra Wenta ◽  
John J. Cassano
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Katabatic Wind ◽  
Surface Conditions ◽  
Terra Nova Bay ◽  
Terra Nova ◽  
Wind Events

scholarly journals The Atmospheric Boundary Layer and Surface Conditions during Katabatic Wind Events over the Terra Nova Bay Polynya

2020 ◽  
Vol 12 (24) ◽  
pp. 4160
Author(s):  
Marta Wenta ◽  
John J. Cassano
Keyword(s):  
Open Water ◽  
Unmanned Aircraft ◽  
Katabatic Wind ◽  
Katabatic Winds ◽  
Surface Conditions ◽  
Terra Nova Bay ◽  
Coastal Polynya ◽  
Terra Nova ◽  
Wind Events ◽  
Aircraft System

Off the coast of Victoria Land, Antarctica an area of open water—the Terra Nova Bay Polynya (TNBP)—persists throughout the austral winter. The development of this coastal polynya is driven by extreme katabatic winds blowing down the slopes of Transantarctic Mountains. The surface-atmosphere coupling and ABL transformation during the katabatic wind events between 18 and 25 September 2012 in Terra Nova Bay are studied, using observations from Aerosonde unmanned aircraft system (UAS), numerical modeling results and Antarctic Weather Station (AWS) measurements. First, we analyze how the persistence and strength of the katabatic winds relate to sea level pressure (SLP) changes in the region throughout the studied period. Secondly, the polynya extent variations are analysed in relation to wind speed changes. We conclude that the intensity of the flow, surface conditions in the bay and regional SLP fluctuations are all interconnected and contribute to polynya development. We also analyse the Antarctic Mesoscale Prediction System (AMPS) forecast for the studied period and find out that incorrect representation of vertical ABL properties over the TNBP might be caused by overestimated sea ice concentrations (SIC) used as model input. Altogether, this research provides a unique description of TNBP development and its interactions with the atmosphere and katabatic winds.

scholarly journals Frazil ice growth and production during katabatic wind events in the Ross Sea, Antarctica

2019 ◽  
Author(s):  
Lisa De Pace ◽  
Madison Smith ◽  
Jim Thomson ◽  
Sharon Stammerjohn ◽  
Steve Ackley ◽  
...  
Keyword(s):  
Ross Sea ◽  
Vertical Mixing ◽  
Katabatic Wind ◽  
Frazil Ice ◽  
Wind Speeds ◽  
Terra Nova Bay ◽  
Air Temperatures ◽  
Terra Nova ◽  
Wind Events ◽  
Ice Production

Abstract. During katabatic wind events in the Terra Nova Bay and Ross Sea polynyas, wind speeds exceeded 20 m s−1, air temperatures were below −25 ℃, and the mixed layer extended as deep as 600 meters. Yet, upper ocean temperature and salinity profiles were not perfectly homogeneous, as would be expected with vigorous convective heat loss. Instead, the profiles revealed bulges of warm and salty water directly beneath the ocean surface and extending downwards tens of meters. Considering both the colder air above and colder water below, we suggest the increase in temperature and salinity reflects latent heat and salt release during unconsolidated frazil ice production within the upper water column. We use a simplified salt budget to analyze these anomalies to estimate in-situ frazil ice concentration between 332 × 10−3 and 24.4 × 10−3 kg m−3. Contemporaneous estimates of vertical mixing by turbulent kinetic energy dissipation reveal rapid convection in these unstable density profiles, and mixing lifetimes from 2 to 12 minutes. The corresponding median rate of ice production is 26 cm day−1 and compares well with previous empirical and model estimates. Our individual estimates of ice production up to 378 cm day−1 reveal the intensity of short-term ice production events during the windiest episodes of our occupation of Terra Nova Bay Polynya.

scholarly journals Thermal, pressure and wind fields at ground level in the area of the Italian base at Terra Nova Bay, Victoria Land, Antarctica, as observed by a network of automatic weather stations

1996 ◽  
Vol 14 (10) ◽  
pp. 1088-1094 ◽  
Author(s):  
E. Cogliani ◽  
G. Abbate ◽  
S. Racalbuto
Keyword(s):  
Wind Speed ◽  
Coastal Region ◽  
Ground Level ◽  
Katabatic Wind ◽  
Wind Fields ◽  
The North ◽  
Terra Nova Bay ◽  
Spatial Configurations ◽  
Weather Stations ◽  
Terra Nova

Abstract. Ground temperature, pressure and wind speed monthly averages in the area of the Italian Station at Terra Nova Bay, Antarctica, were analyzed for the period 1987–1991 by means of a network of nine AWS (automatic weather stations). Spatial configurations of temperature show a well-defined, relatively warm island in the area of Terra Nova Bay, between Drygalsky and Campbell ice tongues, throughout the year. A second warm island is present to the north along the coast, between Aviator and Mariner ice tongues, for most of the year. From February to March a rapid drop in temperature is observed at all stations. A strong thermal gradient develops during February, March, April and October, November, December, between the coastal region and inner highlands. The baric configuration follows the elevation of the area. Annual average pressure and temperature as functions of stations altitude show linear trends. Severe katabatic wind episodes are recorded at all stations, with wind speed exceeding 25 m s–1 and direction following the orographic features of the inner areas. Co-occurrences of these episodes were observed for stations located along stream lines of cold air drainage. The autocorrelation function of maximum wind speed time series shows wind persistence of 2–3 days and wind periodicity of about one week.

scholarly journals Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA-evolution

2012 ◽  
Vol 12 (4) ◽  
pp. 9331-9375 ◽  
Author(s):  
R. H. H. Janssen ◽  
J. Vilà-Guerau de Arellano ◽  
L. N. Ganzeveld ◽  
P. Kabat ◽  
J. L. Jimenez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Land Surface ◽  
Large Scale ◽  
Organic Aerosol ◽  
Layer Growth ◽  
Combined Effects ◽  
Free Troposphere ◽  
Surface Conditions ◽  
Boundary Layer Dynamics

Abstract. We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to well reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment) must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA) concentration. An examination of the budgets of organic aerosol and terpene concentration shows that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically examine the role of the land surface, which governs both the surface energy balance partitioning and terpene-emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene-emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore it influences the relationship between organic aerosol and terpene-concentrations. Our findings indicate that the diurnal evolution of SOA in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.

Novel Physical Simulators for Non-Synoptic Wind Systems

2020 ◽  
Author(s):  
Horia Hangan ◽  
Maryam Refan ◽  
Partha P. Sarkar ◽  
Delong Zuo
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Three Dimensional ◽  
Wind Tunnels ◽  
Wind Effects ◽  
The Past ◽  
Synoptic Wind ◽  
Physical Simulations ◽  
Wind Events ◽  
New Generation

The study of wind effects on buildings and structures is primarily based on physical simulations of wind events. Synoptic, atmospheric boundary layer (ABL) winds have been simulated in boundary layer wind tunnels. Non-synoptic wind events such as tornadoes and downbursts are three-dimensional, dynamic, and non-stationary, and, as a result, a new generation of physical simulators have emerged in the past decades. Some of these simulators, their performances as well as their limitations, are reviewed in this chapter.

Source identification of atmospheric particle-bound metals at Terra Nova Bay, Antarctica

2015 ◽  
Vol 12 (2) ◽  
pp. 245 ◽  
Author(s):  
Andrea Bazzano ◽  
Francesco Soggia ◽  
Marco Grotti
Keyword(s):  
Temporal Trends ◽  
Austral Summer ◽  
Anthropogenic Sources ◽  
Anthropogenic Source ◽  
Katabatic Wind ◽  
High Concentration ◽  
Sea Ice Extent ◽  
Terra Nova Bay ◽  
Terra Nova ◽  
The Impact

Environmental context The atmosphere above Antarctica, the cleanest part of the Earth’s troposphere, serves as a valuable laboratory for studying natural atmospheric processes and for monitoring the impact of human activities on the global environment. Central to these studies is an understanding of long-range transport of pollutants to Antarctica, and distinguishing the relative contribution of natural and anthropogenic sources. We use chemical tracers and isotopic analysis to assess the origin of metals associated with atmospheric particulates in Antarctica. Abstract During the 2010–2011 austral summer, size-segregated aerosol samples were collected at a coastal Antarctic site (Terra Nova Bay, Victoria Land) and analysed for major and trace elements and lead isotopic composition, in order to provide a better understanding of the sources of metals and their transportation pathways towards Antarctica. Aerosol size fractionation was performed by a cascade impactor, able to collect aerosol particles of aerodynamic diameter 10–7.2, 7.2–3.0, 3.0–1.5, 1.5–0.95 and 0.95–0.49µm. It was found that Al, Co, Fe, Li, Mn, Rb, Y and V were mainly related to crustal inputs, whereas the marine contribution was significant for Li, Mg, Na and Rb. An additional anthropogenic source influencing the concentration of Cr, Cu, Mo and Pb was clearly demonstrated. The concentration of the elements associated to the crustal and marine inputs showed high values in the coarse mode (7.2–3.0µm), whereas the anthropogenic elements were also characterised by a high concentration in the finer (1.5–0.95µm) particles. The study of the temporal trends of the measured chemical markers along with the meteorological variables revealed that both the crustal and anthropogenic elements were related to the air masses carried by the katabatic wind from the inland, whereas the marine input appeared to be higher in January when the sea-ice extent was reduced. Finally, lead isotope ratios pointed out that the anthropogenic input was likely related to the polluted aerosols from South America and Australia, representing the predominant fraction (50–70%) of the lead measured in the samples.

scholarly journals Distribution and pattern of shallow melting at the local glaciers of Terra Nova Bay (Antarctica) coast

2004 ◽  
Vol 39 ◽  
pp. 483-489 ◽  
Author(s):  
Luigi Motta ◽  
Michele Motta
Keyword(s):  
Mass Balance ◽  
Wind Erosion ◽  
Frontal Area ◽  
Katabatic Wind ◽  
Glacier Mass Balance ◽  
Relative Importance ◽  
Terra Nova Bay ◽  
Fundamental Process ◽  
Glacial Processes ◽  
Terra Nova

AbstractMelting is a fundamental process in glacier mass balance as well as in other glacial processes such as ice movement, ice avalanches and snow metamorphism. At Terra Nova Bay, Antarctica, the annual mean temperature is <0˚C but melting is not negligible. Our data show that melting is present up to 1300ma.s.l. The distribution and relative importance of melting change with elevation and exposure. At low elevation and with a southerly exposure, melting is one of the major summer ablation processes, synergetic with dry calving and katabatic wind. Meltwater seepage reaches the glacier substrate. Discharge appears to be linked to irradiation, offset by a few hours relative to it. The frontal area of the glaciers therefore behaves like an aquifer, and its characteristics depend on the morphology of the front. As elevation increases, melting at first becomes limited to the snowpack, then to low-albedo cases, for example when dust is brought in from the areas surrounding the glacier. In this case, melting limits ablation, providing the snow with increased resistance to wind erosion.

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