Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica

2020 ◽  
Vol 32 (3) ◽  
pp. 223-237
Author(s):  
Jade P. Lawrence ◽  
Peter T. Doran ◽  
Luke A. Winslow ◽  
John C. Priscu
Keyword(s):  
Water Column ◽  
Internal Waves ◽  
Open Water ◽  
Surface Discharge ◽  
Katabatic Wind ◽  
Neutral Buoyancy ◽  
Cold Temperatures ◽  
Glacier Terminus ◽  
Wind Events ◽  
Taylor Glacier

AbstractBrine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

A pilot study on the interactions between katabatic winds and polynyas at the Adélie Coast, eastern Antarctica

1995 ◽  
Vol 7 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Ute Adolphs ◽  
Gerd Wendler
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Katabatic Wind ◽  
Data Sets ◽  
Strong Wind ◽  
Coastal Sea ◽  
Coastal Winds ◽  
Temperature Contrast ◽  
Wind Events ◽  
Anomalous Wind

Infrared satellite images of the coastal area off Adélie Land were examined together with two wind data sets, one from the manned French station, Dumont d'Urville, the other one from an Automatic Weather Station (AWS) during the 1986 austral winter. A correlation between the development of open water areas (polynyas) and the appearance of extremely strong offshore winds can be drawn. The wind direction tended to be more perpendicular to the coastline during these extreme ‘events’, suggesting a katabatic origin of the increase in wind strength. In the study area the influence of the katabatic wind on the sea ice extends 20–100 km offshore. Sea ice motion further off the coast seems to be more dominated by synoptic scale weather systems. Broader scale atmospheric influences may create large polynya structures which influence the development of coastal winds, as the temperature contrast between open water and the cold continent generates its own circulation. Strong wind events can have a weakening effect on the coastal sea ice which can lead to a much more sensitive reaction of the sea ice in response to following anomalous wind events.

scholarly journals Sublimation and surface energy budget of Taylor Glacier, Antarctica

2011 ◽  
Vol 57 (204) ◽  
pp. 684-696 ◽  
Author(s):  
Andrew K. Bliss ◽  
Kurt M. Cuffey ◽  
Jeffrey L. Kavanaugh
Keyword(s):  
Temporal Variations ◽  
Surface Energy Budget ◽  
Katabatic Wind ◽  
Dry Valleys ◽  
Sublimation Rate ◽  
Ice Dynamics ◽  
Annual Total ◽  
Wind Events ◽  
Taylor Glacier ◽  
Sublimation Rates

AbstractTaylor Glacier, an outlet of the East Antarctic ice sheet, flows through the Transantarctic Mountains and terminates in the Dry Valleys. Understanding how this glacier fluctuates is important for studies of glacial geology, paleoclimate, ice dynamics and ecology. Sublimation is the primary mass-loss process for most of the glacier. Four years of specific balance measurements from the ablation zone show sublimation rates up to 40 cm a−1. We used data from an array of weather stations as inputs to a model for latent heat flux and hence sublimation rate. Calculated and measured ablation rates agree to within uncertainties, indicating that wind speed and vapour pressure gradient (a function of temperature and humidity) are the governing variables, as expected from theory. Measurements and model results together allowed us to examine the spatial and temporal variations of sublimation on the glacier. On average, sublimation is about two times faster in summer than winter. Rapid sublimation occurs during storms and katabatic wind events, but such periods contribute less to the annual total than do slow, persistent losses. Spatially, sublimation reaches a maximum midway along the glacier, where descending surface air currents are focused by the topography of the aptly named tributary, Windy Gully.

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.

Phosphorus Budgets and Stoichiometry during the Open-Water Season in Two Unmanipulated Lakes in the Experimental Lakes Area, Northwestern Ontario

1994 ◽  
Vol 51 (12) ◽  
pp. 2739-2755 ◽  
Author(s):  
P. Campbell
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Open Water ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Phosphorus Budgets ◽  
Mass Balance Approach ◽  
Primary And Secondary Producers ◽  
Column Total

A comparative mass-balance approach is used to describe and quantify phosphorus (P) cycles during the open-water season in two unmanipulated Experimental Lakes Area (ELA) lakes. A bimodal cycle generally prevailed, in which water-column total phosphorus (TP = total dissolved P plus sestonic particulate P) peaked just after ice-out and again late in the summer. Changes in mass of water-column TP were often much larger than corresponding net external inputs. Shifts of P to and from either zooplankton or fish in the water column do not explain the P residuals. Rather, the bottom sediments must have been adding P to the water column. Short-term regeneration of P from the bottom sediments also probably occurs in artificially eutrophied ELA lakes. The mechanism of regeneration is probably biological. Other aspects of P cycling and P stoichiometry are discussed, particularly in relation to nutrient control of population structure and the function of primary and secondary producers.

Colonization by lake benthos of hard substrata in the water column versus on the bottom

1998 ◽  
Vol 49 (2) ◽  
pp. 157 ◽  
Author(s):  
G. P. Quinn ◽  
P. S. Lake ◽  
E. S. G. Schreiber
Keyword(s):  
Water Column ◽  
Benthic Macroinvertebrates ◽  
Open Water ◽  
Almost All ◽  
Benthic Animals ◽  
Hard Substrata

Little work has been done on colonization by lake benthos, particularly onto hard substrata. This study experimentally compared the rates of colonization of hard substrata (bricks) in a lake by benthic macroinvertebrates from two sources — the water column and the bottom. Colonization onto bricks (as mimics of stones) placed on the bottom of the lake was compared with colonization onto bricks suspended in the water column, where they could not be reached by crawling fauna. Almost all taxa colonizing bottom bricks also colonized suspended bricks, including taxa usually considered benthic (e.g. gastropods, mites, oligochaetes and planarians). Water-column samples confirmed the presence of these taxa in open water. These results suggest that many benthic animals in lakes may move through the water column more readily than previously considered; constant movement by lake benthos may be in response to shortage of resources.

Influence of extended water column mixing during the first 2 years of hypolimnetic oxygenation on the phytoplankton community of Amisk Lake, Alberta

1997 ◽  
Vol 54 (9) ◽  
pp. 2133-2145 ◽  
Author(s):  
D J Webb ◽  
R D Robarts ◽  
E E Prepas
Keyword(s):  
Water Column ◽  
Trophic Status ◽  
Phytoplankton Community ◽  
Euphotic Zone ◽  
Open Water ◽  
Eutrophic Lake ◽  
Cyanobacterial Blooms ◽  
Chl A ◽  
Hypolimnetic Oxygenation ◽  
Physical Variables

The phytoplankton community, physical variables, and nutrient and chlorophyll a (Chl a) concentrations were monitored during the first two of six open-water seasons of hypolimnetic oxygenation in double-basined Amisk Lake, Alberta. Deep mixing of the water column in the treated basin (Zmax = 34 m) in spring was enhanced by hypolimnetic oxygenation. Oxygenation began in June 1988, when stratification was likely already established, but subsequent year-round treatment favoured an extended spring diatom bloom (Asterionella formosa and Cyclotella spp.), followed by a delay in the development of, and reduction in the severity of, cyanobacterial blooms (Aphanizomenon flos-aquae and Anabaena flos-aquae) in 1989. Historically, mean summer Chl a and total phosphorus (TP) concentrations in the euphotic zone (0-6 m) of the treated basin were 15.9 ± 1.6 and 33.5 ± 1.5 µg ·L-1, respectively, indicating a eutrophic lake. In 1988 and 1989, mean summer Chl a (10.0 ± 0.6 and 8.1 ± 0.7 µg ·L-1, respectively) and TP concentrations (29.0 ± 0.5 and 22.5 ± 0.9 µg ·L-1, respectively) in this stratum were lower than historic values (P < 0.05), indicating that the trophic status of Amisk Lake had shifted towards mesotrophy.

Characterization of the photoautotrophic algal and bacterial communities in a large, shallow, subtropical lake using HPLC-PDA based pigment analysis

1998 ◽  
Vol 55 (1) ◽  
pp. 206-219 ◽  
Author(s):  
Alan D Steinman ◽  
Karl E Havens ◽  
J William Louda ◽  
Nancy M Winfree ◽  
Earl W Baker
Keyword(s):  
Water Column ◽  
Chlorophyll A ◽  
High Performance ◽  
Principal Component ◽  
Open Water ◽  
High Performance Liquid Chromatographic ◽  
Lake Okeechobee ◽  
Pheophytin A ◽  
Pigment Analysis ◽  
Liquid Chromatographic

Pigment abundances of the oxygenic and anoxygenic photoautotrophic communities from sediments and the water column in Lake Okeechobee, Florida, were estimated using reverse-phase high-performance liquid chromatographic (RP-HPLC) and photodiode array (PDA) UV/VIS (350-800 nm) spectrophotometric analyses. Thirty lipophilic pigments were identified and measured in the samples, with the most abundant overall (sediment and open-water samples combined) being chlorophyll a (38.1%), fucoxanthin (12.6%), pheophytin a (7.6%), zeaxanthin (6.6%), and pyropheophytin a (3.6%). Relative abundance of chlorophyll a was greater in the water column than in the sediments (58.3 versus 24.3% of all pigments) whereas pheophytin a comprised 9.1% of the total pigments in the sediments but only 3.7% of the total pigments in the water column. Principal component analysis (PCA) separated the sediment samples from those collected in the water column; this discrimination appears to be a function of pigment integrity in that sediment assemblages had much greater relative abundances of degraded pigments. Different regions of the lake were weakly separated by PCA based on pigments. The relatively weak degree of separation may reflect the overwhelming abundance of chlorophyll a at all sites. Overall, the pigment assemblage in Lake Okeechobee suggests cyanobacteria-diatom dominance. Out of 65 sampling events, pigments from anoxygenic photoautotrophs (e.g., bacteriochlorophylls) were detected 17 times but accounted for >20% of total chlorophyll only five times. Bacteriochlorophylls were observed only in the sediments and were most abundant during June and September, when winds were calm and temperatures warm, and at relatively shallow sites.

scholarly journals Supplementary material to "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 ◽  
Katabatic Wind ◽  
Ice Growth ◽  
Frazil Ice ◽  
Supplementary Material ◽  
Wind Events

scholarly journals INFLUENCE OF ABIOTIC FACTORS ON FEATURES AND DISTRIBUTION DYNAMICS OF FISH IN SMALL TRIBUTARY OF IRTYSH RIVER

2020 ◽  
Vol 2020 (4) ◽  
pp. 66-80
Author(s):  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Water Level ◽  
Abiotic Factors ◽  
Open Water ◽  
Water Area ◽  
Fish Distribution ◽  
Fish Density ◽  
Water Turbidity ◽  
The North ◽  
Wind Events ◽  
Distribution Of Fish

The article focuses on the studies carried out in the flooded floodplain of the small river Varpak in the basin of the lower Irtysh during the spring flood (in May). The influence of abi-otic factors on the distribution of fish, including juveniles of cyprinids, percids and pike was analyzed. It was found that during the research period there was a direct correlation between the fish density and the temperature and water level, i.e. the fish density increased, as well as the mentioned indicators. There was found the regularity of decreasing the proportion of percids and fish density along with increasing water turbidity in the periods of the southern (S) and south-western (SW) winds, which is stipulated by the wind and wave fish set-down and their independent movement to the shallow areas of the flooded floodplain; In the periods of the north (N) and northeast (NE) winds the fish density increased along with water turbidity, i.e. the fish moved from the shallow water zones to the open water area. The investigated section of the Varpak River is open to the winds of the mentioned directions due of its location and relief. When considering the direction of the fish density distribution during the period of wind events S, SW, N and NE, there has been registered the similarity between the wind direction and the fish distribution in the water area of the floodplain. As a result of the analysis during the observation period the influence of the turbidity factor on the distribution of fish is noted; the greater turbidity, the greater the proportion of cyprinids and the lower the proportion of percids, which can be explained by the specific behavior of these groups of fish. Thus, there is a direct and indirect effect of a number of environmental factors (temperature and water level, wind phenomena and turbidity) on the characteristics and dynamics of fish distribution in the flooded floodplain of the river in the spring period

scholarly journals Bud dormancy pattern, chilling requirement, and cold hardiness in Vitis vinifera L. cv. ‘Chardonnay’ and ‘Riesling’

2021 ◽  
Author(s):  
Alireza Rahemi ◽  
Helen Fisher ◽  
Adam Dale ◽  
Toktam Taghavi ◽  
John M. Kelly
Keyword(s):  
Vitis Vinifera ◽  
Low Temperatures ◽  
Lake Erie ◽  
Cold Hardiness ◽  
Open Water ◽  
Vitis Vinifera L ◽  
Cold Temperatures ◽  
Commercial Vineyard ◽  
Chilling Hours ◽  
Dormancy Pattern

In recent years, new vineyards have been established in southwestern Ontario. The open water of Lake Erie provides some winter protection for Vitis hybrids and winter-hardy Vitis vinifera L. cultivars in this area. However, winter damage is possible when vines are grown distant from the open water or when lakes are frozen. To better understand the risks to winter survival, the dormancy and chilling phenology were studied over three winters from 2013-2016. Ten dormant canes of two V. vinifera cultivars, ‘Chardonnay’ and ‘Riesling’, were collected weekly from September 1 until March 30 from the mature vines in a commercial vineyard located at St. Williams (Ontario). The canes defoliated in early October, and the endodormancy was completed by the end of December. The cumulative chilling hours (0-7.2 °C) from defoliation until the completion of endodormancy were averaged 606 hours for ‘Chardonnay’ and 665 hours for ‘Riesling’. ‘Chardonnay’ buds were slightly less hardy than ‘Riesling’ to cold temperatures, with a threshold of about -24 °C for ‘Chardonnay’ and -25 °C for ‘Riesling’. Most primary buds of both cultivars died after February 16, 2015, and more than half died after February 12, 2014, due to severe low temperatures of -33.1 and -26 °C, respectively.

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