scholarly journals Impact of Argo Observation on the Regional Ocean Reanalysis of China Coastal Waters and Adjacent Seas: A Twin-Experiment Study

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Caixia Shao ◽  
Lili Xuan ◽  
Yingzhi Cao ◽  
Xiaojian Cui ◽  
Siyu Gao
Keyword(s):  
Coastal Waters ◽  
Unique Feature ◽  
Information Service ◽  
Deep Ocean ◽  
Ocean Reanalysis ◽  
Rms Error ◽  
Regional Reanalysis ◽  
Argo Profiles ◽  
The Impact

A regional ocean reanalysis system of China coastal waters and adjacent seas, called CORA (China ocean reanalysis), has been recently developed at the National Marine Data and Information Service (NMDIS). In this study, based on CORA, the impact of Argo profiles on the regional reanalysis is evaluated using a twin-experiment approach. It is found that, by assimilating Argo observations, the reanalysis quality is much improved: the root mean square (RMS) error of temperature and salinity can be further reduced by about 10% and the RMS error of current can be further reduced by 18%, compared to the case only assimilating conventional in situ temperature and salinity observations. Consistent with the unique feature of Argo observations, the temperature is improved in all levels and the largest improvement of salinity happens in the deep ocean. Argo profile data have a significant impact on the regional ocean reanalysis through improvements of both hydrographic and dynamic fields.

scholarly journals Assessing an Atmospheric Correction Algorithm for Time Series of Satellite-Based Water-Leaving Reflectance Using Match-Up Sites in Australian Coastal Waters

2021 ◽  
Vol 13 (10) ◽  
pp. 1927
Author(s):  
Fuqin Li ◽  
David Jupp ◽  
Thomas Schroeder ◽  
Stephen Sagar ◽  
Joshua Sixsmith ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Atmospheric Correction ◽  
Correction Method ◽  
In Situ Measurements ◽  
Landsat 8 ◽  
Correction Algorithm ◽  
Simple Method ◽  
North East ◽  
The Impact

An atmospheric correction algorithm for medium-resolution satellite data over general water surfaces (open/coastal, estuarine and inland waters) has been assessed in Australian coastal waters. In situ measurements at four match-up sites were used with 21 Landsat 8 images acquired between 2014 and 2017. Three aerosol sources (AERONET, MODIS ocean aerosol and climatology) were used to test the impact of the selection of aerosol optical depth (AOD) and Ångström coefficient on the retrieved accuracy. The initial results showed that the satellite-derived water-leaving reflectance can have good agreement with the in situ measurements, provided that the sun glint is handled effectively. Although the AERONET aerosol data performed best, the contemporary satellite-derived aerosol information from MODIS or an aerosol climatology could also be as effective, and should be assessed with further in situ measurements. Two sun glint correction strategies were assessed for their ability to remove the glint bias. The most successful one used the average of two shortwave infrared (SWIR) bands to represent sun glint and subtracted it from each band. Using this sun glint correction method, the mean all-band error of the retrieved water-leaving reflectance at the Lucinda Jetty Coastal Observatory (LJCO) in north east Australia was close to 4% and unbiased over 14 acquisitions. A persistent bias in the other strategy was likely due to the sky radiance being non-uniform for the selected images. In regard to future options for an operational sun glint correction, the simple method may be sufficient for clear skies until a physically based method has been established.

scholarly journals Sea level budget over 2005–2013: missing contributions and data errors

2015 ◽  
Vol 12 (3) ◽  
pp. 701-734
Author(s):  
H. B. Dieng ◽  
A. Cazenave ◽  
K. von Schuckmann ◽  
M. Ablain ◽  
B. Meyssignac
Keyword(s):  
Sea Level ◽  
Heat Content ◽  
Deep Ocean ◽  
Time Span ◽  
Short Time Scale ◽  
Altimetry Data ◽  
Ocean Reanalysis ◽  
Steric Sea Level ◽  
Ocean Mass ◽  
The Impact

Abstract. Based on the sea level budget closure approach, this study investigates the residuals between observed global mean sea level (GMSL) and the sum of components (steric sea level and ocean mass) for the period January 2005 to December 2013. The objective is to identify the impact of errors in one or several components of the sea level budget on the residual time series. This is a key issue if we want to constrain missing contributions such as the contribution to sea level rise from the deep ocean (> 2000m). For that purpose, we use several data sets as processed by different groups: six altimetry products for the GMSL, four Argo products plus the ORAS4 ocean reanalysis for the steric sea level and three GRACE-based ocean mass products. We find that over the study time span, the observed trend differences in the residuals of the sea level budget can be as large as ~0.55mm yr−1. These trend differences essentially result from the processing of the altimetry data (e.g., choice the geophysical corrections and method of averaging the along-track altimetry data). At short time scale (from sub-seasonal to multi-annual), residual anomalies are significantly correlated with ocean mass and steric sea level anomalies (depending on the time span), indicating that the residual anomalies are related to errors in both GRACE-based ocean mass and Argo-based steric data. Efforts are needed to reduce these various sources of errors before using the sea level budget approach to estimate missing contributions such as the deep ocean heat content.

scholarly journals Phytoplankton and Bacterial Response to Desert Dust Deposition in the Coastal Waters of the Southeastern Mediterranean Sea: A Four-Year In Situ Survey

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 305 ◽  
Author(s):  
Eyal Rahav ◽  
Natalia Belkin ◽  
Adina Paytan ◽  
Barak Herut
Keyword(s):  
Mediterranean Sea ◽  
Coastal Waters ◽  
Standing Stock ◽  
Dust Emission ◽  
Deep Ocean ◽  
Biomass Accumulation ◽  
Storm Events ◽  
Atmospheric Conditions ◽  
Dust Deposition

Atmospheric dust/aerosol deposition is an important source of external nutrients for the surface of the ocean. This study shows high-resolution observational data gathered in situ over a period of four years on bacterial and phytoplankton abundance and activity during typical background atmospheric conditions and during intense dust storm events in the low-nutrient, low-chlorophyll (LNLC) coastal waters of the southeastern Mediterranean Sea (SEMS). Chlorophyll a (an estimate for phytoplankton biomass) and bacterial abundance show moderate changes in response to dust deposition/events (−10% and +20%, respectively), while primary production, bacterial production, and N2 fixation rates were all significantly and positively affected by deposition (+25 to +40%; p < 0.05). The rapid changes in bacterial and/or phytoplankton rate parameters suggest that the released micro-/macronutrients from atmospheric deposition are tunneled directly in metabolic processes and, to a lesser extent, for biomass accumulation. The predicted expansion of LNLC areas in oceans in the future, and the projected increase in dust emission due to desertification, may affect the production of marine microbial communities in the surface of the ocean, yet only moderately affect their biomass or standing stock. Such alterations may impact carbon sequestration to the deep ocean.

scholarly journals Sea level budget over 2005–2013: missing contributions and data errors

Ocean Science ◽  
2015 ◽  
Vol 11 (5) ◽  
pp. 789-802 ◽  
Author(s):  
H. B. Dieng ◽  
A. Cazenave ◽  
K. von Schuckmann ◽  
M. Ablain ◽  
B. Meyssignac
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Heat Content ◽  
Deep Ocean ◽  
Time Span ◽  
Ocean Reanalysis ◽  
Argo Data ◽  
Steric Sea Level ◽  
Ocean Mass ◽  
The Impact

Abstract. Based on the sea level budget closure approach, this study investigates the residuals between observed global mean sea level (GMSL) and the sum of components (steric sea level and ocean mass) for the period January 2005 to December 2013. The objective is to identify the impact of errors in one or several components of the sea level budget on the residual time series. This is a key issue if we want to constrain missing contributions such as the contribution to sea level rise from the deep ocean (depths not covered by observations). For that purpose, we use several data sets as processed by different groups: six altimetry products for the GMSL, four Argo products plus the ORAS4 ocean reanalysis for the steric sea level and three GRACE-based ocean mass products. We find that over the study time span, the observed differences in trend of the residuals of the sea level budget equation can be as large as ~ 0.55 mm yr−1 (i.e., ~ 17 % of the observed GMSL rate of rise). These trend differences essentially result from differences in trends of the GMSL time series. Using the ORAS4 reanalysis (providing complete geographical coverage of the steric sea level component), we also show that lack of Argo data in the Indonesian region leads to an overestimate of the absolute value of the residual trend by about 0.25 mm yr−1. Accounting for this regional contribution leads to closure of the sea level budget, at least for some GMSL products. At short timescales (from sub-seasonal to interannual), residual anomalies are significantly correlated with ocean mass and steric sea level anomalies (depending on the time span), suggesting that the residual anomalies are related to errors in both GRACE-based ocean mass and Argo-based steric data. Efforts are needed to reduce these various sources of errors before using the sea level budget approach to estimate missing contributions such as the deep ocean heat content.

The CMEMS In Situ TAC multi-year and multi-variate products to monitor and understand the ocean variability

2021 ◽  
Author(s):  
Tanguy Szekely ◽  
Mélanie Juza ◽  
Jérôme Gourrion ◽  
Paz Rotllán-García ◽  
Sylvie Pouliquen ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Marine Ecosystem ◽  
Deep Ocean ◽  
Global Ocean ◽  
Polar Regions ◽  
Temporal Scales ◽  
Essential Information ◽  
The Impact

&lt;p&gt;The CMEMS In Situ TAC (INSTAC) integrates &lt;em&gt;in situ&lt;/em&gt; observations from various platforms, (e.g. profiling floats, gliders, drifters, saildrones, research vessels, ferryboxes, fixed stations, tides gauges, sea mammals, high-frequency radar), providing physical and biogeochemical ocean data at local, regional and global scales, with an increasing data integration from the polar and coastal regions.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The INSTAC quality-controlled data in both delayed mode and near-real time are contributing to support the operational oceanography (e.g. model forecasting, analysis and reanalysis, satellite calibration, downstream services) and to monitor the 4-dimensional ocean at various spatial and temporal scales. The INSTAC multi-year products provide an essential information on the ocean state, variability and changes and allow addressing long-term variations (climate) analysis as well as detecting remarkable events. Hence, the INSTAC group has contributed substantially to the elaboration of the annual CMEMS Ocean State Report (OSR, &lt;em&gt;Von Schuckmann et al.&lt;/em&gt;, 2016, 2018, 2019, 2020, 2021).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;A general overview of the INSTAC contributions to the CMEMS OSR is presented, highlighting its capacity to describe, analyze and understand the ocean state and variability of both physical and biogeochemical components from the sea surface to the deep ocean, from the coastal to open sea waters, from tropical to polar regions, from semi-enclosed seas to the global ocean, from short-term to long-term temporal scales. The INSTAC team contributes to the CMEMS Ocean Monitoring Indicators reporting, investigates the ocean circulation variability, analyses the impact of climate change on marine ecosystem and ocean circulation, and develops operational applications and services.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Maintaining the current observational network, integrating new platforms, enhancing the spatial and temporal resolutions, improving methodologies and developing new metrics (e.g. quality control, data assimilation), developing new products, INSTAC will continue to serve the overall need to understand and predict the ocean state and variability, in line with the present and future scientific, societal and environmental challenges.&lt;/p&gt;

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

In situ Quantification of the Impact of Episodic Enhanced Turbulent Events in Large Phytoplankton

2011 ◽  
Author(s):  
Percy L. Donaghay ◽  
Jan Rines ◽  
James Sullivan
Keyword(s):  
The Impact

Marine Quality Standards: Their Derivation and Application in the United Kingdom

1985 ◽  
Vol 17 (6-7) ◽  
pp. 1187-1198 ◽  
Author(s):  
G. Mance ◽  
A. R. O'Donnell
Keyword(s):  
Coastal Waters ◽  
Sublethal Effects ◽  
Quality Standards ◽  
Toxicity Data ◽  
Marine Life ◽  
Nickel Zinc ◽  
The United Kingdom ◽  
The Common ◽  
Lead Nickel ◽  
The Impact

This paper discusses the derivation of environmental quality standards for coastal waters and the difficulties of using such standards for controlling industrial discharges. Attention is focused on the common List II substances, copper, chromium, lead, nickel, zinc and arsenic - and their effects on marine life. The adequacy of existing toxicity data is discussed and it is concluded that long exposure tests are required to provide information on sublethal effects. Such data are currently limited. It is also important that consideration be given to the effects that reducing salinities and increasing temperatures have in increasing the toxicity of these substances. The complexity of interpreting the results of laboratory toxicity data to coastal waters is discussed with reference to a study of the impact of an industrial discharge.

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