scholarly journals Sea ice sensitivity to the parameterisation of open water area

2010 ◽  
Vol 3 (2) ◽  
pp. 3-9 ◽  
Author(s):  
Zeliang Wang ◽  
Youyu Lu ◽  
Daniel G Wright ◽  
Frederic Dupont
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Water Area ◽  
Open Water Area

Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 198-202 ◽  
Author(s):  
K. M. Lewis ◽  
G. L. van Dijken ◽  
K. R. Arrigo
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Open Water ◽  
Water Area ◽  
The Arctic ◽  
Carbon Export ◽  
Phytoplankton Primary Production ◽  
Open Water Area ◽  
The Arctic Ocean

Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.

scholarly journals Summer valley-floor snowfall in Taylor Valley, Antarctica from 1995–2017

2020 ◽  
Author(s):  
Madeline E. Myers ◽  
Peter T. Doran ◽  
Krista F. Myers
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Open Water ◽  
Water Area ◽  
Valley Floor ◽  
Radiation Budget ◽  
Valley Bottom ◽  
Sea Ice Extent ◽  
Open Water Area ◽  
Taylor Valley

Abstract. In polar, coastal areas like Taylor Valley, snowfall is predicted to increase under warming conditions as reduced sea ice increases open water area and evaporation potential, thereby creating conditions that would facilitate precipitation. Taylor Valley is a mosaic of glaciers, valley-bottom ice-covered lakes, ephemeral streams and dark, rocky soils. Ecosystems are both light- and nutrient-limited and rely on seasonally available liquid water. Although Taylor Valley receives minimal snowfall annually, light snow cover during summer months reduces radiation for primary productivity and slows melting by increasing the local albedo. Snowfall has been measured at four sites in Taylor Valley since 1995. Daily photographs at the Lake Hoare station in the central portion of the valley record snow cover since 2007 and augment the automated precipitation measurements. Here, we focus on valley-floor snowfall due to its effect on ecosystems in the valley-bottom lakes and streams. Precipitation increased by 3 mm water equivalent (w.e.) a−1 from 1995 to 2009, then decreased by 1 mm w.e. a−1 through 2017. Since 2009, annual snowfall in Taylor Valley ranges from 1 to 30 mm w.e. High snowfall during the Spring near the coast is indicative of high summer snowfall at the more inland Lake Bonney station (r2 = 0.66; p < 0.05). In contrast, the average fraction of days with snow on the ground tripled at Lake Hoare after 2011, primarily during Spring and Fall. Fall snow persistence at Lake Hoare has been increasing by ~ 1 day per year since the start of the record in 2007, although Spring snow cover exhibits no trend. In agreement with previous studies, regression analysis revealed no correlation of snow cover or snowfall with sea ice extent or mean temperatures. Strong seasonality and interannual variability underscores the complexity of precipitation and snow persistence controls in Taylor Valley. In regions where snow cover contributes more to the radiation budget than the hydrologic budget, photographs are the most reliable method for monitoring precipitation. The results of this study highlight the importance of continued monitoring of precipitation throughout Taylor Valley. The establishment of coastal and inland snow cover monitoring stations would augment point observations of snow cover and add spatial complexity to our present understanding of the expected hydrologic and ecosystem response to climate change in Taylor Valley.

Southern Ocean sea-ice distributions and extents

1992 ◽  
Vol 338 (1285) ◽  
pp. 243-250 ◽  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Interannual Variability ◽  
Ross Sea ◽  
Open Water ◽  
Ice Cover ◽  
Water Area ◽  
Weddell Sea ◽  
Open Water Area ◽  
Ice Coverage

Southern Ocean sea-ice coverage undergoes a large seasonal cycle, with a nearly fivefold increase in areal ice extents from the minimum in February to the maximum in September, and significant interannual variations. Results presented here show in a variety of forms some of the variability that occurred in Southern Ocean sea-ice distributions and extents over the 1970s and 1980s. Interannual variability is examined by identifying changes in three measures: sea-ice extents, sea-ice distributions, and the length of the sea-ice season. Regarding these three: (i) Maximum ice extents varied by approximately 12%, decreasing during the mid-1970s, followed by increases over the next few years and a levelling off for much of the 1980s. (ii) The area of interannual variability in monthly average sea-ice distributions in summer far exceeds the summertime area of consistent ice coverage, in sharp contrast to the wintertime situation, when the area of consistent ice coverage is considerably larger. In winter, the ice-distribution variability is largely confined to two regions: a relatively narrow outer band (generally 2-5° of latitude) surrounding the region of consistent ice coverage, and, for the mid-1970s, the region of an occasional large open water area within the ice pack of the Weddell Sea, termed the Weddell polynya. The Weddell and other polynyas within the ice cover allow intensified heat, mass, and momentum exchanges between ocean and atmosphere, thereby affecting regional oceanic and atmospheric circulations, (iii) The length of the sea-ice season, calculated for the years 1979-1986, with satellite passive-microwave data coverage through all months of the year, showed increases over that period in the Ross Sea but decreases in the Weddell and Bellingshausen seas. In both cases it appears, through comparisons with data from 1973-1976, that the 1979-1986 changes more likely reflect a fluctuating behaviour of the ice cover than a long-term trend. The changes in the ice cover have influences not only on the ocean and the atmosphere but on aquatic plant and animal life as well.

Towards a Model of Regional Vessel Near-miss Collision Risk Assessment for Open Waters based on AIS Data

2019 ◽  
Vol 72 (06) ◽  
pp. 1449-1468 ◽  
Author(s):  
Weibin Zhang ◽  
Xinyu Feng ◽  
Yong Qi ◽  
Feng Shu ◽  
Yijin Zhang ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Safety Management ◽  
Open Water ◽  
Water Area ◽  
Assessment System ◽  
Near Miss ◽  
Collision Risk ◽  
Accurate Analysis ◽  
Open Water Area ◽  
Temporal Features

The absence of a regional, open water vessel collision risk assessment system endangers maritime traffic and hampers safety management. Most recent studies have analysed the risk of collision for a pair of vessels and propose micro-level risk models. This study proposes a new method that combines density complexity and a multi-vessel collision risk operator for assessing regional vessel collision risk. This regional model considers spatial and temporal features of vessel trajectory in an open water area and assesses multi-vessel near-miss collision risk through danger probabilities and possible consequences of collision risks via four types of possible relative striking positions. Finally, the clustering method of multi-vessel encountering risk, based on the proposed model, is used to identify high-risk collision areas, which allow reliable and accurate analysis to aid implementation of safety measures.

scholarly journals Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2651
Author(s):  
Qiang Liu ◽  
Liqiao Liang ◽  
Xiaomin Yuan ◽  
Sirui Yan ◽  
Miao Li ◽  
...  
Keyword(s):  
Water Level ◽  
Open Water ◽  
Water Area ◽  
Water Level Fluctuation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Water Evaporation ◽  
Level Fluctuation ◽  
Open Water Area ◽  
Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

scholarly journals Autumn bacterioplankton of the open waters and coastal part of the Barents Sea

2021 ◽  
Vol 12 (3-2021) ◽  
pp. 36-45
Author(s):  
A.V. Vashchenko ◽  
Keyword(s):  
Coastal Waters ◽  
Barents Sea ◽  
Open Water ◽  
Bottom Layer ◽  
Water Area ◽  
Northeastern Part ◽  
Autumn Season ◽  
Open Water Area ◽  
The Barents Sea

The paper presents the results of microbiological studies carried out in the Motovsky Bay (2017) and the northeastern part of the Barents Sea (2020) in October. It was shown that, with comparable values of abundance, the biomass of bacterioplankton in open waters was slightly higher than in coastal waters. The quantity was 148–717 thousand cells/ml in Motovsky Bay and 170–957 thousand cells/ml in the open water area. The biomass was 7.26–29.07 mg/m3 in Motovsky Bay and 9.71–51.39 mg/m3 in the open water area. The maximum values were in the 0–50 m layer,the minimum – in the bottom layer in both areas. Those results supplement the existing understanding of bacterioplanktons development and distribution in the Barents Sea in the autumn season.

Studying the bottom landscapes of Lake Ladoga with use of underwater vehicles

2020 ◽  
Author(s):  
Vladimir Anokhin ◽  
Dina Dudakova ◽  
Mikhael Dudakov
Keyword(s):  
Coastal Zone ◽  
High Efficiency ◽  
Open Water ◽  
Underwater Vehicles ◽  
Water Area ◽  
Gps Tracking ◽  
Lake Ladoga ◽  
Underwater Video ◽  
Open Water Area ◽  
First Time

&lt;p&gt;In 2019, the Institute of Limnology of the Russian Academy of Sciences (IL RAS) carried out geological and geomorphological studies of the bottom and shores of Lake Ladoga within the framework of the State project of the IL RAS No. 0154-2018-0003 / 5. The research included the study of the bottom landscapes of Lake Ladoga with help of a series of underwater vehicles Limnoscout, designed and assembled at the IL RAS.&lt;/p&gt;&lt;p&gt;Underwater photo and video of the bottom in the coastal zone was carried out by the Limnoscout-230 vehicle from a boat. Each video filming polygon &amp;#160;included 2 continuous video profiles of 1-2 km normal to the shore, and 1 connecting profile parallel to the shore of 200-400 m, in the deep part.&lt;/p&gt;&lt;p&gt;Underwater video filming of the bottom in the open water area of &amp;#8203;&amp;#8203;the lake was carried out by the Limnoscout-50 vehicle from the board of the r/v &amp;#8220;Poseidon&amp;#8221;, by point diving, in which the bottom was shot within a radius of 2-4 m from the dive point.&lt;/p&gt;&lt;p&gt;Maximal deep of studies was 117 m.&lt;/p&gt;&lt;p&gt;All underwater surveys were accompanied by echo-sounding surveys and GPS tracking.&lt;/p&gt;&lt;p&gt;In total, 24 underwater video filming&amp;#160; polygons in the coastal zone and 23 underwater video filming points in the open water area of &amp;#8203;&amp;#8203;the northern part of Lake Ladoga were worked out.&lt;/p&gt;&lt;p&gt;The collected extensive photo and video materials made it possible to make preliminary typology of the bottom landscapes of Lake Ladoga and evaluate their condition.&lt;/p&gt;&lt;p&gt;Several new important facts of the structure of the bottom of Lake Ladoga and biota distribution were discovered, in particular:&lt;/p&gt;&lt;p&gt;- For the first time on the bottom of Lake Ladoga, an invasive species of mollusk Dreissena polymorpha was discovered, which in other large lakes has a significant impact on ecosystems.&lt;/p&gt;&lt;p&gt;- For the first time at the bottom in the northern part of the lake, outlets of presumably Riphean sandstones were discovered, which significantly complements the geological picture of the area.&lt;/p&gt;&lt;p&gt;- For the first time at the bottom in the northeastern part of the lake an abnormally deep occurrence of coarse deposits was discovered, which is likely to be associated with the intense activity of glaciers.&lt;/p&gt;&lt;p&gt;The use of underwater photo and video in combination with traditional methods for studying the bottom landscapes of Lake Ladoga has shown the high efficiency of these methods. The studies will be continued.&lt;/p&gt;

scholarly journals MICROPLASTICS POLLUTION MONITORING IN BOTTOM SEDIMENTS OF THE SEVASTOPOL REGION RECREATION ZONES

2021 ◽  
pp. 91-101
Author(s):  
E.N. Sibirtsova ◽  
◽  
A.V. Temnykh ◽  
M.I. Silakov ◽  
◽  
...  
Keyword(s):  
Bottom Sediments ◽  
World Ocean ◽  
Open Water ◽  
Dry Weight ◽  
Water Area ◽  
Pollution Monitoring ◽  
Open Water Area ◽  
Water Edge ◽  
Order Of Magnitude ◽  
Frag Ments

A study of the concentration of microplastic pollution (MP) in the bottom sediments of the water areas adjoining recreation zones (RZ) of the Sevastopol region in 2018 - 2020 was carried out. An increase in MP was registered practically in all areas, the average values of MP concentration were 13.4 items•kg-1 dry weight. As for the shape of microplastics (MPs) particles, the maximum share was made up by frag-ments (50-83%), fibers were also numerous (33%). A significant increase in the concentration of MP on the 0-20 m section of the underwater coastal slope from the water edge was recorded in zones with an open water area and presence of a cliff. The revealed level of MP is comparable to that in the Mediterra-nean, Caspian, Baltic Seas, but an order of magnitude lower than in other regions of the World Ocean.

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