Mechanisms controlling primary and new production in a global ecosystem  model – Part II: The role of the upper ocean short-term periodic and episodic mixing events

Abstract. The use of 6 h, daily, weekly and monthly atmospheric forcing resulted in dramatically different predictions of plankton productivity in a global 3-D coupled physical-biogeochemical model. Resolving the diurnal cycle of atmospheric variability by use of 6 h forcing, and hence also diurnal variability in UML depth, produced the largest difference, reducing predicted global primary and new production by 25% and 10% respectively relative to that predicted with daily and weekly forcing. This decrease varied regionally, being a 30% reduction in equatorial areas primarily because of increased light limitation resulting from deepening of the mixed layer overnight as well as enhanced storm activity, and 25% at moderate and high latitudes primarily due to increased grazing pressure resulting from late winter stratification events. Mini-blooms of phytoplankton and zooplankton occur in the model during these events, leading to zooplankton populations being sufficiently well developed to suppress the progress of phytoplankton blooms. A 10% increase in primary production was predicted in the peripheries of the oligotrophic gyres due to increased storm-induced nutrient supply end enhanced winter production during the short term stratification events that are resolved in the run forced by 6 h meteorological fields. By resolving the diurnal cycle, model performance was significantly improved with respect to several common problems: underestimated primary production in the oligotrophic gyres; overestimated primary production in the Southern Ocean; overestimated magnitude of the spring bloom in the subarctic Pacific Ocean, and overestimated primary production in equatorial areas. The result of using 6 h forcing on predicted ecosystem dynamics was profound, the effects persisting far beyond the hourly timescale, and having major consequences for predicted global and new production on an annual basis.

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Mechanisms controlling primary and new production in a global ecosystem model – Part II: the role of the upper ocean short-term periodic and episodic mixing events

Ocean Science Discussions ◽

10.5194/osd-3-1115-2006 ◽

2006 ◽

Vol 3 (4) ◽

pp. 1115-1148

Author(s):

E. E. Popova ◽

A. C. Coward ◽

G. A. Nurser ◽

B. de Cuevas ◽

T. R. Anderson

Keyword(s):

Primary Production ◽

Diurnal Cycle ◽

Model Performance ◽

Ecosystem Model ◽

Ecosystem Dynamics ◽

Biogeochemical Model ◽

Atmospheric Variability ◽

New Production ◽

Diurnal Variability ◽

Episodic Mixing

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Short term variations of tracer transit speed on alpine glaciers

The Cryosphere ◽

10.5194/tc-4-381-2010 ◽

2010 ◽

Vol 4 (3) ◽

pp. 381-396 ◽

Cited By ~ 16

Author(s):

M. A. Werder ◽

T. V. Schuler ◽

M. Funk

Keyword(s):

Drainage System ◽

Relative Importance ◽

Short Term ◽

Diurnal Variability ◽

Alpine Glacier ◽

Two Component ◽

Transit Speed ◽

Underlying Processes ◽

Diurnal Maximum ◽

Tracer Experiments

Abstract. We first present the results of a series of tracer experiments conducted on an alpine glacier (Gornergletscher, Switzerland) over a diurnal discharge cycle. For these injections, a moulin was used into which an ice marginal lake was draining, providing a relatively constant discharge. The measured tracer transit speeds show two diurnal maxima and minima. These findings are qualitatively different to existing observations from two series of injections conducted at Unteraargletscher (Switzerland) using a moulin fed by supraglacial meltwater having a high diurnal variability, which displayed one diurnal maximum and minimum. We then develop and use a simple two-component model of the glacier drainage system, comprising a moulin and a channel element, to simulate the measured transit speeds for all three injection series. The model successfully reproduces all the observations and shows that the same underlying processes can produce the qualitatively different behaviour depending on the different moulin input discharge regimes. Using the model, we assess the relative importance of the different measurement quantities, show that frequent measurements of moulin input discharge are indispensable and propose an experiment design to monitor the development of the drainage system over several weeks.

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Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean

ICES Journal of Marine Science ◽

10.1093/icesjms/fss113 ◽

2012 ◽

Vol 69 (7) ◽

pp. 1180-1193 ◽

Cited By ~ 62

Author(s):

Zachary W. Brown ◽

Kevin R. Arrigo

Keyword(s):

Sea Ice ◽

Primary Production ◽

Arctic Ocean ◽

Bering Sea ◽

Net Primary Productivity ◽

Remote Sensing Data ◽

Ice Cover ◽

The Arctic ◽

Light Limitation ◽

The Bering Sea

Abstract Brown, Z. W., and Arrigo, K. R. 2012. Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean. – ICES Journal of Marine Science, 69: . Satellite remote sensing data were used to examine recent trends in sea-ice cover and net primary productivity (NPP) in the Bering Sea and Arctic Ocean. In nearly all regions, diminished sea-ice cover significantly enhanced annual NPP, indicating that light-limitation predominates across the seasonally ice-covered waters of the northern hemisphere. However, long-term trends have not been uniform spatially. The seasonal ice pack of the Bering Sea has remained consistent over time, partially because of winter winds that have continued to carry frigid Arctic air southwards over the past six decades. Hence, apart from the “Arctic-like” Chirikov Basin (where sea-ice loss has driven a 30% increase in NPP), no secular trends are evident in Bering Sea NPP, which averaged 288 ± 26 Tg C year−1 over the satellite ocean colour record (1998–2009). Conversely, sea-ice cover in the Arctic Ocean has plummeted, extending the open-water growing season by 45 d in just 12 years, and promoting a 20% increase in NPP (range 441–585 Tg C year−1). Future sea-ice loss will likely stimulate additional NPP over the productive Bering Sea shelves, potentially reducing nutrient flux to the downstream western Arctic Ocean.

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The diurnal cycle of cloud profiles over land and ocean between 51° S and 51° N, seen by the CATS spaceborne lidar from the International Space Station

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-9457-2018 ◽

2018 ◽

Vol 18 (13) ◽

pp. 9457-9473 ◽

Cited By ~ 18

Author(s):

Vincent Noel ◽

Hélène Chepfer ◽

Marjolaine Chiriaco ◽

John Yorks

Keyword(s):

High Altitude ◽

International Space Station ◽

Diurnal Cycle ◽

Space Station ◽

Cloud Fraction ◽

Vertical Profiles ◽

Diurnal Variability ◽

International Space ◽

Low Level ◽

Diurnal Cycles

Abstract. We document, for the first time, how detailed vertical profiles of cloud fraction (CF) change diurnally between 51∘ S and 51∘ N, by taking advantage of 15 months of measurements from the Cloud-Aerosol Transport System (CATS) lidar on the non-sun-synchronous International Space Station (ISS). Over the tropical ocean in summer, we find few high clouds during daytime. At night they become frequent over a large altitude range (11–16 km between 22:00 and 04:00 LT). Over the summer tropical continents, but not over ocean, CATS observations reveal mid-level clouds (4–8 km above sea level or a.s.l.) persisting all day long, with a weak diurnal cycle (minimum at noon). Over the Southern Ocean, diurnal cycles appear for the omnipresent low-level clouds (minimum between noon and 15:00) and high-altitude clouds (minimum between 08:00 and 14:00). Both cycles are time shifted, with high-altitude clouds following the changes in low-altitude clouds by several hours. Over all continents at all latitudes during summer, the low-level clouds develop upwards and reach a maximum occurrence at about 2.5 km a.s.l. in the early afternoon (around 14:00). Our work also shows that (1) the diurnal cycles of vertical profiles derived from CATS are consistent with those from ground-based active sensors on a local scale, (2) the cloud profiles derived from CATS measurements at local times of 01:30 and 13:30 are consistent with those observed from CALIPSO at similar times, and (3) the diurnal cycles of low and high cloud amounts (CAs) derived from CATS are in general in phase with those derived from geostationary imagery but less pronounced. Finally, the diurnal variability of cloud profiles revealed by CATS strongly suggests that CALIPSO measurements at 01:30 and 13:30 document the daily extremes of the cloud fraction profiles over ocean and are more representative of daily averages over land, except at altitudes above 10 km where they capture part of the diurnal variability. These findings are applicable to other instruments with local overpass times similar to CALIPSO's, such as all the other A-Train instruments and the future EarthCARE mission.

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Phenological phases of pollination related to climate change

10.5194/egusphere-egu21-15034 ◽

2021 ◽

Author(s):

Samuel Monnier ◽

Michel Thibaudon ◽

Jean-Pierre Besancenot ◽

Charlotte Sindt ◽

Gilles Oliver

Keyword(s):

Climate Change ◽

Pollen Season ◽

Microscopic Analysis ◽

Allergic Diseases ◽

Early Spring ◽

Late Winter ◽

General Tendency ◽

New Production ◽

Start Date ◽

Generic Term

Knowledge:Rising CO2 levels and climate change may be resulting in some shift in the geographical range of certain plant species, as well as in increased rate of photosynthesis. Many plants respond accordingly with increased growth and reproduction and possibly greater pollen yields, that could affect allergic diseases among other things.The aim of this study is the evolution of aerobiological measurements in France for 25-30 years. This allows to follow the main phenological parameters in connection with the pollination and the ensuing allergy risk.Material and method:The RNSA (French Aerobiology Network) has pollen background-traps located in more than 60 towns throughout France. These traps are volumetric Hirst models making it possible to obtain impacted strips for microscopic analysis by trained operators. The main taxa studied here are birch, grasses and ragweed for a long period of more than 25 years over some cities of France.Results:Concerning birch but also other catkins or buds&#8217; trees pollinating in late winter or spring, it can be seen an overall advance of the pollen season start date until 2004 and then a progressive delay, the current date being nearly the same as it was 20 years ago, and an increasing trend in the quantities of pollen emitted.For grasses and ragweed, we only found a few minor changes in the start date but a longer duration of the pollen season.Discussion:As regards the trees, the start date of the new production of catkins or buds is never the 1st of January but depends on the species. For example, it is early July for birch. For breaking dormancy, flowering, and pollinating, the trees and other perennial species need a period of accumulation of cold degrees (Chilling) and later an accumulation of warm degrees (Forcing). With climate change these periods may be shorter or longer depending of the autumn and winter temperature. Therefore, a change in the annual temperature may have a direct effect on the vegetal physiology and hence on pollen release. It may also explain why the quantities of pollen produced are increasing.The Poaceae reserve, from one place to another and without any spatial structuring, very contrasted patterns which make it impossible to identify a general tendency. This is probably due to the great diversity of taxa grouped under the generic term Poaceae, which are clearly not equally sensitive to climate change.Conclusion:Trees with allergenic pollen blowing late winter or early spring pollinate since 2004 later and produce amounts of pollen constantly increasing. Grasses and ragweed have longer periods of pollination with either slightly higher or most often lower pollen production.

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Characterizing the diurnal cycle of South Atlantic stratocumulus cloud properties from satellite retrievals

10.5194/acp-2018-445 ◽

2018 ◽

Author(s):

Chellappan Seethala ◽

Jan Fokke Meirink ◽

Ákos Horváth ◽

Ralf Bennartz ◽

Rob Roebeling

Keyword(s):

Diurnal Variation ◽

Biomass Burning ◽

Diurnal Cycle ◽

Near Infrared ◽

South Atlantic ◽

Radiation Budget ◽

Ozone Monitoring Instrument ◽

Liquid Water Path ◽

Diurnal Variability ◽

Late Afternoon

Abstract. Marine stratocumulus (Sc) clouds play an essential role in the earth radiation budget. Here, we compare liquid water path (LWP), optical thickness (COT), and effective radius (CER) retrievals from two years of collocated Spinning Enhanced Visible and InfraRed Imager (SEVIRI), MODerate resolution Imaging Spectroradiometer (MODIS), and Tropical Rainfall Measuring Mission Microwave Imager (TMI) observations, estimate the effect of biomass burning smoke on passive imager retrievals, as well as evaluate the diurnal cycle of South Atlantic marine Sc clouds. The effect of absorbing aerosols from biomass burning on the retrievals was investigated using aerosol index (AI) obtained from the Ozone Monitoring Instrument (OMI). SEVIRI and MODIS LWPs were found to decrease with increasing AI relative to TMI LWP, consistent with well-known negative visible/near-infrared retrieval biases in COT and CER. In the aerosol-affected months of July–August–September, SEVIRI LWP – based on the 1.6-µm CER – was biased low by 14 g m−2 (~ 16 %) compared to TMI in overcast scenes, while MODIS LWP showed a smaller low bias of 4 g m−2 (~ 5 %) for the 1.6-µm channel and a high bias of 8 g m−2 (~ 10 %) for the 3.7-µm channel compared to TMI. Neglecting aerosol-affected pixels reduced the mean SEVIRI-TMI LWP bias considerably. On a two-year data base, SEVIRI LWP had a correlation with TMI and MODIS LWP of about 0.86 and 0.94, respectively, and biases of only 4–8 g m−2 (5–10 %) for overcast cases. The SEVIRI LWP diurnal cycle was in good overall agreement with TMI except in the aerosol-affected months. Both TMI and SEVIRI LWP decreased from morning to late afternoon, after which a slight increase was observed. Terra and Aqua MODIS mean LWPs also suggested a similar diurnal variation. The relative amplitude of the two-year mean and seasonal mean LWP diurnal cycle varied between 35–40 % from morning to late afternoon for overcast cases. The diurnal variation in SEVIRI LWP was mainly due to changes in COT, while CER showed only little diurnal variability.

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Extractable aromatic hydrocarbons in a short-term organic cycle of the Kimmeridge Clay formation, Yorkshire (U.K.): relationship to primary production and thermal maturity

Organic Geochemistry ◽

10.1016/0146-6380(95)80002-9 ◽

1995 ◽

Vol 23 (9) ◽

pp. 803-817 ◽

Cited By ~ 11

Author(s):

Lalanirina R. Ramanampisoa ◽

Matthias Radke

Keyword(s):

Primary Production ◽

Aromatic Hydrocarbons ◽

Thermal Maturity ◽

Short Term ◽

Clay Formation

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Using new observations and Machine Learning to improve organic sinking processes in the PlankTOM global ocean biogeochemical model

10.5194/egusphere-egu21-11356 ◽

2021 ◽

Author(s):

Anna Denvil-Sommer ◽

Corinne Le Quéré ◽

Erik Buitenhuis ◽

Lionel Guidi ◽

Jean-Olivier Irisson

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Deep Ocean ◽

Ecosystem Dynamics ◽

Global Ocean ◽

Biogeochemical Model ◽

Carbon Export ◽

Mixing Depth ◽

Chl A ◽

Biogeochemical Models

A lot of effort has been put in the representation of surface ecosystem processes in global carbon cycle models, in particular through the grouping of organisms into Plankton Functional Types (PFTs) which have specific influences on the carbon cycle. In contrast, the transfer of ecosystem dynamics into carbon export to the deep ocean has received much less attention, so that changes in the representation of the PFTs do not necessarily translate into changes in sinking of particulate matter. Models constrain the air-sea CO2 flux by drawing down carbon into the ocean interior. This export flux is five times as large as the CO2 emitted to the atmosphere by human activities. When carbon is transported from the surface to intermediate and deep ocean, more CO2 can be absorbed at the surface. Therefore, even small variability in sinking organic carbon fluxes can have a large impact on air-sea CO2 fluxes, and on the amount of CO2 emissions that remain in the atmosphere.In this work we focus on the representation of organic matter sinking in global biogeochemical models, using the PlankTOM model in its latest version representing 12 PFTs. We develop and test a methodology that will enable the systematic use of new observations to constrain sinking processes in the model. The approach is based on a Neural Network (NN) and is applied to the PlankTOM model output to test its ability to reconstruction small and large particulate organic carbon with a limited number of observations. We test the information content of geographical variables (location, depth, time of year), physical conditions (temperature, mixing depth, nutrients), and ecosystem information (CHL a, PFTs). These predictors are used in the NN to test their influence on the model-generation of organic particles and the robustness of the results. We show preliminary results using the NN approach with real plankton and particle size distribution observations from the Underwater Vision Profiler (UVP) and plankton diversity data from Tara Oceans expeditions and discuss limitations.

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Net Primary Production in the Shortgrass Steppe

Ecology of the Shortgrass Steppe ◽

10.1093/oso/9780195135824.003.0016 ◽

2008 ◽

Author(s):

William K. Lauenroth ◽

Daniel G. Milchunas

Keyword(s):

Global Change ◽

Primary Production ◽

Net Primary Production ◽

Regional Scale ◽

Ecosystem Dynamics ◽

Shortgrass Steppe ◽

Annual Precipitation ◽

Mean Annual Precipitation ◽

Spatial And Temporal Patterns ◽

Temporal And Spatial

Net primary production (NPP), the amount of carbon or energy fixed by green plants in excess of their respiratory needs, is the fundamental quantity upon which all heterotrophs and the ecosystem processes they are associated with depend. Understanding NPP is therefore a prerequisite to understanding ecosystem dynamics. Our objectives for this chapter are to describe the current state of our knowledge about the temporal and spatial patterns of NPP in the shortgrass steppe, to evaluate the important variables that control NPP, and to discuss the future of NPP in the shortgrass steppe given current hypotheses about global change. Most of the data available for NPP in the shortgrass steppe are for aboveground net primary production (ANPP), so most of our presentation will focus on ANPP and we will deal with belowground net primary production (BNPP) as a separate topic. Furthermore, our treatment of NPP in this chapter will ignore the effects of herbivory, which will be covered in detail in chapter 16. Our approach will be to start with a regional-scale view of ANPP in shortgrass ecosystems and work toward a site-scale view. We will begin by briefly placing ANPP in the shortgrass steppe in its larger context of the central North American grassland region. We will then describe the regional-scale patterns and controls on ANPP, and then move to the site-scale patterns and controls on ANPP. At the site scale, we will describe both temporal and spatial dynamics, and controls on ANPP as well as BNPP. We will then discuss relationships between spatial and temporal patterns in ANPP and end the chapter with a short, speculative section on how future global change may influence NPP in the shortgrass steppe. Temperate grasslands in central North America are found over a range of mean annual precipitation from 200 to 1200 mm.y–1 and mean annual temperatures from 0 to 20 oC (Lauenroth et al., 1999). The widely cited relationship between mean annual precipitation and average annual ANPP allows us to convert the precipitation gradient into a production gradient (Lauenroth, 1979; Lauenroth et al., 1999; Noy-Meir, 1973; Rutherford, 1980; Sala et al., 1988b).

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Seasonal patterns in phytoplankton biomass across the northern and deep Gulf of Mexico: a numerical model study

Biogeosciences ◽

10.5194/bg-15-3561-2018 ◽

2018 ◽

Vol 15 (11) ◽

pp. 3561-3576 ◽

Cited By ~ 13

Author(s):

Fabian A. Gomez ◽

Sang-Ki Lee ◽

Yanyun Liu ◽

Frank J. Hernandez Jr. ◽

Frank E. Muller-Karger ◽

...

Keyword(s):

Gulf Of Mexico ◽

Primary Production ◽

Phytoplankton Biomass ◽

Mississippi Delta ◽

Three Dimensional ◽

Rate Of Change ◽

Integrated Analysis ◽

Biogeochemical Model ◽

Seasonal Patterns ◽

Biogeochemical Models

Abstract. Biogeochemical models that simulate realistic lower-trophic-level dynamics, including the representation of main phytoplankton and zooplankton functional groups, are valuable tools for improving our understanding of natural and anthropogenic disturbances in marine ecosystems. Previous three-dimensional biogeochemical modeling studies in the northern and deep Gulf of Mexico (GoM) have used only one phytoplankton and one zooplankton type. To advance our modeling capability of the GoM ecosystem and to investigate the dominant spatial and seasonal patterns of phytoplankton biomass, we configured a 13-component biogeochemical model that explicitly represents nanophytoplankton, diatoms, micro-, and mesozooplankton. Our model outputs compare reasonably well with observed patterns in chlorophyll, primary production, and nutrients over the Louisiana–Texas shelf and deep GoM region. Our model suggests silica limitation of diatom growth in the deep GoM during winter and near the Mississippi delta during spring. Model nanophytoplankton growth is weakly nutrient limited in the Mississippi delta year-round and strongly nutrient limited in the deep GoM during summer. Our examination of primary production and net phytoplankton growth from the model indicates that the biomass losses, mainly due to zooplankton grazing, play an important role in modulating the simulated seasonal biomass patterns of nanophytoplankton and diatoms. Our analysis further shows that the dominant physical process influencing the local rate of change of model phytoplankton is horizontal advection in the northern shelf and vertical mixing in the deep GoM. This study highlights the need for an integrated analysis of biologically and physically driven biomass fluxes to better understand phytoplankton biomass phenologies in the GoM.

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