scholarly journals Distinct Seasonal Primary Production Patterns in the Sub-Polar Gyre and Surrounding Seas

2021 ◽  
Vol 8 ◽  
Author(s):  
Katherine Richardson ◽  
Jørgen Bendtsen
Keyword(s):  
Primary Production ◽  
Mixed Layer Depth ◽  
Water Masses ◽  
Surrounding Water ◽  
Study Region ◽  
East Greenland ◽  
Model Studies ◽  
Dominant Feature ◽  
Ocean Carbon ◽  
Annual Distribution

Primary production (PP) in the sub-polar region appears to be important for ocean carbon uptake but how the different water masses contribute to the PP occurring here has not yet been described. Using two models based on satellite observations of surface chlorophyll, light and temperature, seasonal patterns in the distribution of PP are shown here to differ in the sub-polar gyre south of the Greenland-Scotland Ridge (GSR) and surrounding water masses. Monthly averages of PP (2003–2013) were determined. Total and seasonal PP were similar in both models. Average PP in five of the domains (0.47–0.77 g C m–2 d–1) was well above the global average (0.37 g C m–2 d–1). Over the East Greenland shelf, however, total annual PP was estimated to be only 0.19 g C m–2 d–1. The Norwegian shelf was the most productive of the regions studied. “Spring blooms” appear sporadically as spikes in the annual distribution of PP in some regions/years, but do not emerge as a dominant feature in the average annual development of PP in any of the domains. For all regions, ∼25% of the annual PP takes place in the period January-May. PP peaked over most of the study area at or around maximum insolation or temperature. PP in the study region as a whole appears to be more related to latitude or water masses than to bathymetry. In waters over the East Greenland shelf, the Norwegian shelf, and north of the GSR up to 50% of annual PP had taken place when ∼50% of the annual flux of light has reached the surface. In contrast, only about 35% of annual PP had taken place in the sub-polar gyre and waters over the southern open shelf by this time. Light-use efficiency differences may be explained by differences in mixed layer depth (MLD). Multi-model Earth System model studies have indicated that climate change may decrease the MLD in the sub-polar gyre and suggest this may lead to a decrease in the PP occurring here. The results presented here, however, suggest that a shallower MLD could lead to an increase in PP.

scholarly journals Evaluation and improvement of the Community Land Model (CLM 4.0) in Oregon forests

2012 ◽  
Vol 9 (9) ◽  
pp. 12757-12802
Author(s):  
T. W. Hudiburg ◽  
B. E. Law ◽  
P. E. Thornton
Keyword(s):  
Primary Production ◽  
Forest Inventory ◽  
Net Primary Production ◽  
Forest Carbon ◽  
Physiological Parameters ◽  
Process Models ◽  
Study Region ◽  
Stem Biomass ◽  
Community Land Model ◽  
Semi Arid

Abstract. Ecosystem process models are important tools for determining the interactive effects of global change and disturbance on forest carbon dynamics. Here we evaluated and improved terrestrial carbon cycling simulated by the Community Land Model (CLM4), the land model portion of the Community Earth System Model (CESM1.0.4). Our analysis was conducted primarily in Oregon forests using FLUXNET and forest inventory data for the period 2001–2006. We go beyond prior modeling studies in the region by incorporating regional variation in physiological parameters from >100 independent field sites in the region. We also compare spatial patterns of simulated forest carbon stocks and net primary production (NPP) at 15 km resolution using data collected from federal forest inventory plots (FIA) from >3000 plots in the study region. Finally, we evaluate simulated gross primary production (GPP) with FLUXNET eddy-covariance tower data at wet and dry sites in the region. We improved model estimates by making modifications to CLM4 to allow physiological parameters (e.g. foliage carbon to nitrogen ratios and specific leaf area), mortality rate, biological nitrogen fixation, and wood allocation to vary spatially by plant functional type (PFT) within an ecoregion based on field plot data in the region. Prior to modifications, default parameters resulted in underestimation of stem biomass in all forested ecoregions except the Blue Mountains and annual NPP was both over and underestimated. After modifications, model estimates of mean NPP fell within the observed range of uncertainty in all ecoregions (two-sided p-value = 0.8) and the underestimation of stem biomass was reduced. This was an improvement from the default configuration by 50% for stem biomass and 30% for NPP. At the tower sites, modeled monthly GPP fell within the observed range of uncertainty at both sites for the majority of the year, however summer GPP was underestimated at the Metolius semi-arid pine site and spring GPP was overestimated at the Campbell River mesic Douglas-fir site, indicating GPP may be an area for further improvement. The low bias in summer maximum GPP at the semi-arid site could be due to seasonal response of Vcmax to temperature and precipitation while overestimated spring values at the mesic site could be due to response of Vcmax to temperature and daylength.

scholarly journals C14 content of recent molluscs from Scoresby Sund, central East Greenland

1975 ◽  
Vol 75 ◽  
pp. 95-99
Author(s):  
H Tauber ◽  
S Funder
Keyword(s):  
North Atlantic ◽  
East Coast ◽  
Marine Organisms ◽  
Water Masses ◽  
Lower Activity ◽  
Terrestrial Plants ◽  
East Greenland ◽  
The North ◽  
The North Atlantic ◽  
Turn Over

C14 dating of subfossil marine shelIs presupposes a knowledge of the original C14 activity of the organisms while living. Due to the slow turn over of water masses, the C14 activity of marine bicarbonate and marine organisms is not the same in all parts of the oceans, but may show marked deficiencies in certain oceanic areas, especially at southern latitudes. In large areas of the North Atlantic the C14 activity seems to be fairly uniform and equal to or only slightly lower than that of 'pre-industrial' terrestrial plants (Broecker et al., 1960; Mangerud, 1972; Krog & Tauber, 1974). In certain areas, however, a somewhat lower activity seems to occur; trus has been noted for areas along the east coast of Greenland (Fonselius & Ostlund, 1959; Hjort, 1973).

Study of the sea ice impact on primary production in the Barents and Kara Seas in past and future climates

2021 ◽  
Author(s):  
Stanislav D. Martyanov ◽  
Anton Y. Dvornikov ◽  
Vladimir A. Ryabchenko ◽  
Dmitry V. Sein
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Marine Ecosystem ◽  
Short Wave ◽  
Steering Committee ◽  
Wave Radiation ◽  
Primary Role ◽  
Short Wave Radiation ◽  
Ocean Carbon ◽  
Barents And Kara Seas

<p>A regional coupled eco-hydrodynamic model of the Barents and Kara Seas based on the MITgcm has been developed. The biogeochemical module is based on a 7-component model of pelagic biogeochemistry including the ocean carbon cycle. This regional model allows revealing and explaining the main mechanisms of the interaction between marine dynamic and biogeochemical processes in the Barents and Kara Seas under a changing climate. We present the main results of simulations for the past (1975-2005) and future (2035-2065) climate.</p><p>A clear relationship between the marginal ice zone area and primary production has been obtained, proving the importance of this zone in the functioning of the marine ecosystem. The interannual variability of the integrated primary production and the total sea ice area demonstrates an antiphase behavior, which means that the reduced sea ice cover area in the previous winter is one of the main reasons for the increase in primary production in the current year.</p><p>The model simulations demonstrate that, of all the external factors, sea ice area plays a primary role in the formation of primary production: in the overwhelming majority of cases, the contribution of the ice area prevails, and the pattern "more ice - less primary production" and vice versa is fulfilled in the Barents and Kara Seas. The effect of a decrease of incoming short-wave radiation becomes significant only when a significant decrease of the ice area occurs.</p><p>Compared to the period 1975-2005, the simulated total primary production in the Barents and Kara Seas is much higher for the period 2035-2065, while the sea ice area significantly decreases.</p><p>A regression dependence has been obtained for the total annual primary production as a function of sea ice area and incoming short-wave radiation. Its validity is verified for both past (dependent) and future (independent) climatic periods. It justifies the use of such simple statistical model for quick estimates of the primary production in the Barents and Kara Seas.</p><p>Acknowledgements: The research was performed in the framework of the state assignment of the Ministry of Science and Higher Education of Russia (theme No. 0128-2021-0014). This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID ba1206.</p>

scholarly journals Atlantic-Origin Overflow Water in the East Greenland Current

2019 ◽  
Vol 49 (9) ◽  
pp. 2255-2269 ◽  
Author(s):  
Lisbeth Håvik ◽  
Mattia Almansi ◽  
Kjetil Våge ◽  
Thomas W. N. Haine
Keyword(s):  
Potential Temperature ◽  
Small Degree ◽  
Water Masses ◽  
East Greenland ◽  
Eddy Activity ◽  
Deep Circulation ◽  
Dense Water ◽  
East Greenland Current ◽  
Denmark Strait ◽  
Atlantic Origin

AbstractDense water masses transported southward along the east coast of Greenland in the East Greenland Current (EGC) form the largest contribution to the Denmark Strait Overflow. When exiting Denmark Strait these dense water masses sink to depth and feed the deep circulation in the North Atlantic. Based on one year of mooring observations upstream of Denmark Strait and historical hydrographic profiles between Fram Strait and Denmark Strait, we find that a large part (75%) of the overflow water ( ≥ 27.8 kg m−3) transported by the EGC is of Atlantic origin (potential temperature θ > 0°C). The along-stream changes in temperature of the Atlantic-origin Water are moderate north of 69°N at the northern end of Blosseville basin, but southward from this point the temperature decreases more rapidly. We hypothesize that this enhanced modification is related to the bifurcation of the EGC taking place close to 69°N into the shelfbreak EGC and the separated EGC. This is associated with enhanced eddy activity and strong water mass modification reducing the intermediate temperature and salinity maxima of the Atlantic-origin Water. During periods with a large (small) degree of modification the separated current is strong (weak). Output from a high-resolution numerical model supports our hypothesis and reveals that large eddy activity is associated with an offshore shift of the surface freshwater layer that characterizes the Greenland shelf. The intensity of the eddy activity regulates the density and the hydrographic properties of the Denmark Strait Overflow Water transported by the EGC system.

Phytoplankton Succession and Primary Production in Babine Lake, British Columbia

1975 ◽  
Vol 32 (12) ◽  
pp. 2413-2427 ◽  
Author(s):  
John G. Stockner ◽  
K. R. S. Shortreed
Keyword(s):  
Primary Production ◽  
Sockeye Salmon ◽  
Mixed Layer Depth ◽  
Carbon Assimilation ◽  
Annual Production ◽  
Phosphate Limitation ◽  
The South ◽  
South Basin ◽  
The North ◽  
Principal Factors

Ten stations located in six zones (subbasins) were sampled biweekly from May to October 1973 to detect possible regional differences in production in this large, 155 km long, dystrophic lake. The spring bloom occurred in all zones while a fall bloom occurred only in Zones 5 and 6. Carbon assimilation showed two peaks in south basin zones, but only one (spring) at zones north of Topley Landing. Seasonal variation in phytoplankton numbers and volume, seston, and chlorophyll a followed a pattern similar to that noted for primary production. Mean production was 100 mg C∙m−2∙day−1 in Zones 1–4, but was 145 in Zones 5 and 6. Annual production was estimated at 25 g C∙m−2 in the north basin and 40 in the south basin. Reasons for the regional disparities are discussed, with greatest significance given to regional variations in mixed layer depth, surface inflows (loading), and basin mean depth. The development and sustainment of the autumnal bloom of Tabellaria fenestrata is thought to be one of the principal factors responsible for greater production in the south basin.An estimated 0.05 g TP∙m−2 enters the lake yearly. This can vary depending on the return of adult sockeye salmon (Oncorhynchus nerka), whose carcasses contribute up to 20% of the total. An estimated 30% is lost via the Babine River, and it is speculated that of the remaining 70%, most is lost to the sediments. Phosphate limitation is implied as a chief factor limiting primary production in the north basin stations, but not in the south basin. On the basis of total phosphorus load the lake is classed as oligotrophic, but in terms of annual production and its humic stained waters it is more correctly considered mixotrophic.

scholarly journals The impact of global warming on seasonality of ocean primary production

2013 ◽  
Vol 10 (1) ◽  
pp. 1421-1450 ◽  
Author(s):  
S. Henson ◽  
H. Cole ◽  
C. Beaulieu ◽  
A. Yool
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Nitrate Concentration ◽  
Mixed Layer Depth ◽  
Climate Change Impacts ◽  
The Arctic ◽  
Layer Depth ◽  
Biogeochemical Models ◽  
Ocean Productivity ◽  
The Impact

Abstract. The seasonal cycle (i.e. phenology) of oceanic primary production (PP) is expected to change in response to climate warming. Here, we use output from 6 global biogeochemical models to examine the response in the seasonal amplitude of PP and timing of peak PP to the IPCC AR5 warming scenario. We also investigate whether trends in PP phenology may be more rapidly detectable than trends in PP itself. The seasonal amplitude of PP decreases by an average of 1–2% per year by 2100 in most biomes, with the exception of the Arctic which sees an increase of ~1% per year. This is accompanied by an advance in the timing of peak PP by ~0.5–1 months by 2100 over much of the globe, and particularly pronounced in the Arctic. These changes are driven by an increase in seasonal amplitude of sea surface temperature (where the maxima get hotter faster than the minima) and a decrease in the seasonal amplitude of the mixed layer depth and surface nitrate concentration. Our results indicate a transformation of currently strongly seasonal (bloom forming) regions, typically found at high latitudes, into weakly seasonal (non-bloom) regions, characteristic of contemporary subtropical conditions. On average, 36 yr of data are needed to detect a climate change-driven trend in the seasonal amplitude of PP, compared to 32 yr for mean annual PP. We conclude that analysis of phytoplankton phenology is not necessarily a shortcut to detecting climate change impacts on ocean productivity.

EUREC4A-OA/ATOMIC experiment  : Themohaline and dynamical descriptions of mesoscale and submesoscale structures of the Northwest Tropical Atlantic Ocean

2021 ◽  
Author(s):  
Pierre L'Hégaret ◽  
Sabrina Speich ◽  
Yanxu Chen ◽  
Gaston Manta ◽  
Léa Olivier ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Mesoscale Eddies ◽  
Water Masses ◽  
Ocean Dynamics ◽  
Tropical Atlantic ◽  
Fine Scale ◽  
Surrounding Water ◽  
Tropical Atlantic Ocean ◽  
North Brazil ◽  
Oxygen Concentrations

<p>In January-February 2020, the EUREC4A-OA/ATOMIC experiment took place in the Northwest Tropical Atlantic Ocean with the overall objective of understanding the role of fine scale processes in the internal ocean dynamics and air-sea interaction. Four oceanographic vessels, the French Atalante, German Maria S Merian and Meteor, and the American Ron Brown, closely coordinated with air-borne observations and autonomous ocean platforms (gliders, saildrones, and drifters) to simultaneously measure the ocean and atmosphere east of the island of Barbados and the coast of Guyana in the western Tropical Atlantic. A whole battery of instruments measuring the thermohaline and dynamic characteristics of the region was launched. The fixed CTD stations, reaching great depths while measuring salinity, temperature, and oxygen concentrations, serve as a reference to calibrate and validate other devices, in particular, shallower uCTD, TSG, and MVP, acquired during ship transits, and autonomous gliders and saidrones. Combined, these datasets increase the horizontal resolution and thus the description of structures ranging from mesoscale to fine scale.</p><p>The Northwest Tropical Atlantic Ocean is a dynamical region filled with mesoscale eddies of different origins and transporting various water masses across the region. These eddies have rich and diverse characteristics ranging from shallow cyclonic and anticyclonic eddies to the deep reaching North Brazil Current (NBC) Rings. On the surface, down to 200 m depth, the signatures of shallow cyclones and anticyclones (NBC rings) were measured. The shallow mesoscale eddies, with core centered around a density of 25.5 kg m-3, advect highly saline and warm waters, with low oxygen concentrations compared to the surrounding water masses. Below, evolving at density around 26.7 kg m-3, thick anticyclones were observed, characterized by low temperature and salinity but with high values of oxygen, indicative of a South Atlantic origin. One was observed drifting slowly northward and another one at the NBC retroflection. Similarly, mesoscale cyclonic eddies were also observed both at the surface and at depth. Surface and subsurface eddies are not aligned vertically and they seem to evolve independently. </p><p>The large number and diversity (ship-mounted or autonomous) of observing platforms implemented in the project made made it possible to innovatively sample the upper-ocean frontal scales and stratification. It has been found that the interaction between the particularly fresh waters from the Amazon River, flowing northward along the shelf-break, and NBC rings create a rich variety of submesoscale fronts and a strong barrier layer, leading to interleaving. With the high vertical and horizontal resolutions, we quantify the layering and mixing processes at play.</p>

scholarly journals Simulation of Surface Ozone Pollution in the Central Gulf Coast Region Using WRF/Chem Model: Sensitivity to PBL and Land Surface Physics

2010 ◽  
Vol 2010 ◽  
pp. 1-24 ◽  
Author(s):  
Anjaneyulu Yerramilli ◽  
Venkata Srinivas Challa ◽  
Venkata Bhaskar Rao Dodla ◽  
Hari Prasad Dasari ◽  
John H. Young ◽  
...  
Keyword(s):  
Land Surface ◽  
Gulf Coast ◽  
Surface Ozone ◽  
Mixed Layer Depth ◽  
Land Surface Model ◽  
Surface Model ◽  
Model Sensitivity ◽  
Emission Data ◽  
Study Region ◽  
Diurnal Range

The fully coupled WRF/Chem (Weather Research and Forecasting/Chemistry) model is used to simulate air quality in the Mississippi Gulf coastal region at a high resolution (4 km) for a moderately severe summer ozone episode between 18 CST 7 and 18 CST 10 June 2006. The model sensitivity is studied for meteorological and gaseous criteria pollutants (O3, NO2) using three Planetary Boundary Layer (PBL) and four land surface model (LSM) schemes and comparison of model results with monitoring station observations. Results indicated that a few combinations of PBL and LSMs could reasonably produce realistic meteorological fields and that the combination of Yonsei University (YSU) PBL and NOAH LSM provides best predictions for winds, temperature, humidity and mixed layer depth in the study region for the period of study. The diurnal range in ozone concentration is better estimated by the YSU PBL in association with either 5-layer or NOAH land surface model. The model seems to underestimate the ozone concentrations in the study domain because of underestimation of temperatures and overestimation of winds. The underestimation of NO2by model suggests the necessity of examining the emission data in respect of its accurate representation at model resolution. Quantitative analysis for most monitoring stations indicates that the combination of YSU PBL with NOAH LSM provides the best results for various chemical species with minimum BIAS, RMSE, and high correlation values.

Transformation of dissolved inorganic carbon (DIC) into particulate organic carbon (POC) in the lower Xijiang River, SE China: an isotopic approach

2011 ◽  
Vol 8 (5) ◽  
pp. 9471-9501 ◽  
Author(s):  
H. G. Sun ◽  
J. T. Han ◽  
S. R. Zhang ◽  
X. X. Lu
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Rainy Season ◽  
Chemical Weathering ◽  
Dissolved Inorganic Carbon ◽  
Dry Season ◽  
Study Region ◽  
Carbon Isotopic ◽  
Xijiang River ◽  
Extreme Flood

Abstract. The sources and dynamics of riverine carbon have been discussed extensively, but knowledge about the transformation from DIC into organic carbon (OC) is still poorly understood. In this study, we conducted a comprehensive investigation on the riverine carbon, stable carbon isotopic components and C/N ratios for different seasons, including an extreme flood event, in the lower Xijiang and its three tributaries. Detailed analyses are also performed for soil samples across the study region. Downstream increase in δ13CDIC and downstream decrease in both δ13CPOC and C/N have been observed for all the tributaries. Meanwhile, positive shift of δ13CDIC and negative shift of δ13CPOC are also observed from summer to winter. These observations likely indicate that the isotopic compositions of both DIC and POC are significantly affected by in-river primary production that converts DIC into organic matter through photosynthesis. It is estimated that the percentage contribution of the riverine aquatic primary production to the riverine POC in the Xijiang and three tributaries of Guijiang, Hejiang and Luoding is respectively 7.1%, 43.2%, 36.4% and 9.9% in rainy season, and 35.6%, 47.3%, 50.3% and 40.1% in dry season. Based on the stoichiometry involved in chemical weathering of the bedrocks, the transformation of the carbonate-sourced DIC to POC is further quantified to be 3.4–20.5% in rainy season, and 12.3–22.1% in dry season. This may suggest an important sink of atmospheric CO2 in river systems that was largely ignored previously.

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