scholarly journals On biotic and abiotic drivers of the microphytobenthos seasonal cycle in a temperate intertidal mudflat: a modelling study

2018 ◽  
Author(s):  
Raphaël Savelli ◽  
Christine Dupuy ◽  
Laurent Barillé ◽  
Astrid Lerouxel ◽  
Katell Guizien ◽  
...  
Keyword(s):  
Spring Bloom ◽  
Coupled Model ◽  
Simulated Data ◽  
Grazing Pressure ◽  
Early Spring ◽  
Trophic Levels ◽  
Intertidal Mudflat ◽  
Temperature Optimum ◽  
In Situ Data

Abstract. Microphytobenthos (MPB) from intertidal mudflats are key primary producers at the land-ocean interface. MPB can be more productive than phytoplankton and sustain both benthic and pelagic higher trophic levels. The objective of this study is to assess the contribution of light, mud temperature, and gastropod Peringia ulvae grazing pressure in shaping the seasonal MPB dynamics on the Brouage mudflat (NW France). We use a physical-biological coupled model applied to the sediment first centimeter for the year 2008. The simulated data compare to observations including time-coincident remotely sensed and in situ data. The model suggests a MPB annual cycle characterized by a main spring bloom, a biomass depression in summer, and a moderate fall bloom. In early spring, high simulated photosynthetic rates due to mud surface temperature (MST) values close to the MPB temperature optimum for photosynthesis and to increasing solar irradiance trigger the onset of the MPB spring bloom. After the bloom, high MST values lead to synoptic events when MPB thermo-inhibition (39.5 % of summer) and limitation by P. ulvae grazing (8.7 % of summer) superimpose. During these synoptic events of thermo-inhibition and grazing combination, 14 % of the simulated annual MPB primary production is channeled towards the P. ulvae secondary production through ingestion. The model suggests that such a combined effect is highly linked to the MPB biomass depression in summer. The model ability to infer on biotic and abiotic mechanisms driving the seasonal MPB dynamics could open the door to a new assessment of the export flux of biogenic matter at the land-ocean interface and, more generally, of the contribution of productive intertidal biofilms to the coastal carbon cycle.

scholarly journals On biotic and abiotic drivers of the microphytobenthos seasonal cycle in a temperate intertidal mudflat: a modelling study

2018 ◽  
Vol 15 (23) ◽  
pp. 7243-7271 ◽  
Author(s):  
Raphaël Savelli ◽  
Christine Dupuy ◽  
Laurent Barillé ◽  
Astrid Lerouxel ◽  
Katell Guizien ◽  
...  
Keyword(s):  
Spring Bloom ◽  
Coupled Model ◽  
Simulated Data ◽  
Grazing Pressure ◽  
Early Spring ◽  
Trophic Levels ◽  
Intertidal Mudflat ◽  
In Situ Data ◽  
Primary Production Rate

Abstract. Microphytobenthos (MPB) from intertidal mudflats are key primary producers at the land–ocean interface. MPB can be more productive than phytoplankton and sustain both benthic and pelagic higher trophic levels. The objective of this study is to assess the contribution of light, mud temperature, and gastropod Peringia ulvae grazing pressure in shaping the seasonal MPB dynamics on the Brouage mudflat (NW France). We use a physical–biological coupled model applied to the sediment first centimetre for the year 2008. The simulated data compare to observations, including time-coincident remotely sensed and in situ data. The model suggests an MPB annual cycle characterised by a main spring bloom, a biomass depression in summer, and a moderate fall bloom. In early spring, simulated photosynthetic rates are high due to mud surface temperature (MST) values close to the MPB temperature optimum for photosynthesis and because increasing solar irradiance triggers the onset of the MPB spring bloom. Simulated peaks of high P. ulvae grazing (11 days during which ingestion rates exceed the primary production rate) mostly contribute to the decline of the MPB bloom along with the temperature limitation for MPB growth. In late spring–summer, the MPB biomass depression is due to the combined effect of thermo-inhibition and a moderate but sustained grazing pressure. The model ability to infer biotic and abiotic mechanisms driving the seasonal MPB dynamics could open the door to a new assessment of the export flux of biogenic matter from the coast to the open ocean and, more generally, of the contribution of productive intertidal biofilms to the coastal carbon cycle.

scholarly journals Analysis of Groundwater and Total Water Storage Changes in Poland Using GRACE Observations, In-situ Data, and Various Assimilation and Climate Models

2019 ◽  
Vol 11 (24) ◽  
pp. 2949 ◽  
Author(s):  
Justyna Śliwińska ◽  
Monika Birylo ◽  
Zofia Rzepecka ◽  
Jolanta Nastula
Keyword(s):  
Climate Models ◽  
Water Storage ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Climate Data ◽  
Total Water ◽  
In Situ Data ◽  
Grace Data ◽  
Land Data Assimilation System

The Gravity Recovery and Climate Experiment (GRACE) observations have provided global observations of total water storage (TWS) changes at monthly intervals for over 15 years, which can be useful for estimating changes in GWS after extracting other water storage components. In this study, we analyzed the TWS and groundwater storage (GWS) variations of the main Polish basins, the Vistula and the Odra, using GRACE observations, in-situ data, GLDAS (Global Land Data Assimilation System) hydrological models, and CMIP5 (the World Climate Research Programme’s Coupled Model Intercomparison Project Phase 5) climate data. The research was conducted for the period between September 2006 and October 2015. The TWS data were taken directly from GRACE measurements and also computed from four GLDAS (VIC, CLM, MOSAIC, and NOAH) and six CMIP5 (FGOALS-g2, GFDL-ESM2G, GISS-E2-H, inmcm4, MIROC5, and MPI-ESM-LR) models. The GWS data were obtained by subtracting the model TWS from the GRACE TWS. The resulting GWS values were compared with in-situ well measurements calibrated using porosity coefficients. For each time series, the trends, spectra, amplitudes, and seasonal components were computed and analyzed. The results suggest that in Poland there has been generally no major TWS or GWS depletion. Our results indicate that when comparing TWS values, better compliance with GRACE data was obtained for GLDAS than for CMIP5 models. However, the GWS analysis showed better consistency of climate models with the well results. The results can contribute toward selection of an appropriate model that, in combination with global GRACE observations, would provide information on groundwater changes in regions with limited or inaccurate ground measurements.

Analysis of groundwater storage changes in main Polish river basins using GRACE observations, in-situ data, and hydrological and climate models

2020 ◽  
Author(s):  
Jolanta Nastula ◽  
Justyna Śliwińska ◽  
Zofia Rzepecka ◽  
Monika Birylo
Keyword(s):  
Climate Models ◽  
Water Storage ◽  
Coupled Model ◽  
Research Programme ◽  
Climate Data ◽  
Groundwater Storage ◽  
In Situ Data ◽  
Snow Water ◽  
Land Data Assimilation System

<p>The Gravity Recovery and Climate Experiment (GRACE) measurements have provided global observations of total water storage (TWS) changes at monthly intervals for almost 20 years. They are useful for estimating changes in groundwater storage (GWS) after extracting other water storage components like soil water or snow water.</p><p>In this study, we analyse the GWS variations of two main Polish basins, the Vistula and the Odra, using GRACE observations, in-situ wells measurements, GLDAS (Global Land Data Assimilation System) hydrological models, and CMIP5 (the World Climate Research Programme’s Coupled Model Intercomparison Project Phase 5) climate data. The research is conducted for the period between September 2006 and October 2015.</p><p>Here, TWS is taken directly from GRACE measurements and also computed from all considered models. GWS is obtained by subtracting the modelled sum of soil moisture and snow water from the GRACE-based TWS. The resultant GWS series are validated by comparing with appropriately calibrated in-situ wells measurements. For each GWS time series, the trends, spectra, amplitudes, and seasonal components were computed and analysed. The results suggest that in Poland there has been generally no major GWS depletion. The results can contribute toward selection of an appropriate model that, in combination with GRACE observations, would provide information on groundwater changes in regions with limited or inaccurate in-situ groundwater storage measurements.</p>

scholarly journals Springtime phytoplankton dynamics in Arctic Krossfjorden and Kongsfjorden (Spitsbergen) as a function of glacier proximity

2014 ◽  
Vol 11 (8) ◽  
pp. 2263-2279 ◽  
Author(s):  
A. M.-T. Piquet ◽  
W. H. van de Poll ◽  
R. J. W. Visser ◽  
C. Wiencke ◽  
H. Bolhuis ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Spring Bloom ◽  
Light Attenuation ◽  
Early Spring ◽  
Late Spring ◽  
Trophic Levels ◽  
Rrna Genes ◽  
Phytoplankton Dynamics ◽  
Molecular Fingerprinting ◽  
Bloom Period

Abstract. The hydrographic properties of the Kongsfjorden–Krossfjorden system (79° N, Spitsbergen) are affected by Atlantic water incursions as well as glacier meltwater runoff. This results in strong physical gradients (temperature, salinity and irradiance) within the fjords. Here, we tested the hypothesis that glaciers affect phytoplankton dynamics as early as the productive spring bloom period. During two campaigns in 2007 (late spring) and 2008 (early spring) we studied hydrographic characteristics and phytoplankton variability along two transects in both fjords, using high-performance liquid chromatography (HPLC)-CHEMTAX pigment fingerprinting, molecular fingerprinting (denaturing gradient gel electrophoresis, or DGGE) and sequencing of 18S rRNA genes. The sheltered inner fjord locations remained colder during spring as opposed to the outer locations. Vertical light attenuation coefficients increased from early spring onwards, at all locations, but in particular at the inner locations. In late spring meltwater input caused stratification of surface waters in both fjords. The inner fjord locations were characterized by overall lower phytoplankton biomass. Furthermore HPLC-CHEMTAX data revealed that diatoms and Phaeocystis sp. were replaced by small nano- and picophytoplankton during late spring, coinciding with low nutrient availability. The innermost stations showed higher relative abundances of nano- and picophytoplankton throughout, notably of cyanophytes and cryptophytes. Molecular fingerprinting revealed a high similarity between inner fjord samples from early spring and late spring samples from all locations, while outer samples from early spring clustered separately. We conclude that glacier influence, mediated by early meltwater input, modifies phytoplankton biomass and composition already during the spring bloom period, in favor of low biomass and small cell size communities. This may affect higher trophic levels especially when regional warming further increases the period and volume of meltwater.

scholarly journals Reinitializing Sea Surface Temperature in the Ensemble Intermediate Coupled Model for Improved Forecasts

Axioms ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 189
Author(s):  
Sittisak Injan ◽  
Angkool Wangwongchai ◽  
Usa Humphries ◽  
Amir Khan ◽  
Abdullahi Yusuf
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Oscillation ◽  
Coupled Model ◽  
Sea Surface ◽  
In Situ Data ◽  
The Pacific ◽  
Intermediate Coupled Model ◽  
Sea Surface Temperature Anomalies

The Ensemble Intermediate Coupled Model (EICM) is a model used for studying the El Niño-Southern Oscillation (ENSO) phenomenon in the Pacific Ocean, which is anomalies in the Sea Surface Temperature (SST) are observed. This research aims to implement Cressman to improve SST forecasts. The simulation considers two cases in this work: the control case and the Cressman initialized case. These cases are simulations using different inputs where the two inputs differ in terms of their resolution and data source. The Cressman method is used to initialize the model with an analysis product based on satellite data and in situ data such as ships, buoys, and Argo floats, with a resolution of 0.25 × 0.25 degrees. The results of this inclusion are the Cressman Initialized Ensemble Intermediate Coupled Model (CIEICM). Forecasting of the sea surface temperature anomalies was conducted using both the EICM and the CIEICM. The results show that the calculation of SST field from the CIEICM was more accurate than that from the EICM. The forecast using the CIEICM initialization with the higher-resolution satellite-based analysis at a 6-month lead time improved the root mean square deviation to 0.794 from 0.808 and the correlation coefficient to 0.630 from 0.611, compared the control model that was directly initialized with the low-resolution in-situ-based analysis.

scholarly journals Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling

2018 ◽  
Vol 15 (5) ◽  
pp. 1335-1346 ◽  
Author(s):  
Vincent Le Fouest ◽  
Atsushi Matsuoka ◽  
Manfredi Manizza ◽  
Mona Shernetsky ◽  
Bruno Tremblay ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Arctic Ocean ◽  
Coupled Model ◽  
The Arctic ◽  
In Situ Data ◽  
Basin Scale ◽  
Western Arctic ◽  
Potential Impact

Abstract. Future climate warming of the Arctic could potentially enhance the load of terrigenous dissolved organic carbon (tDOC) of Arctic rivers due to increased carbon mobilization within watersheds. A greater flux of tDOC might impact the biogeochemical processes of the coastal Arctic Ocean (AO) and ultimately its capacity to absorb atmospheric CO2. In this study, we show that sea-surface tDOC concentrations simulated by a physical–biogeochemical coupled model in the Canadian Beaufort Sea for 2003–2011 compare favorably with estimates retrieved by satellite imagery. Our results suggest that, over spring–summer, tDOC of riverine origin contributes to 35 % of primary production and that an equivalent of ∼ 10 % of tDOC is exported westwards with the potential of fueling the biological production of the eastern Alaskan nearshore waters. The combination of model and satellite data provides promising results to extend this work to the entire AO so as to quantify, in conjunction with in situ data, the expected changes in tDOC fluxes and their potential impact on the AO biogeochemistry at basin scale.

Air–Sea Interaction in the Ligurian Sea: Assessment of a Coupled Ocean–Atmosphere Model Using In Situ Data from LASIE07

2011 ◽  
Vol 139 (6) ◽  
pp. 1785-1808 ◽  
Author(s):  
R. J. Small ◽  
T. Campbell ◽  
J. Teixeira ◽  
S. Carniel ◽  
T. A. Smith ◽  
...  
Keyword(s):  
System Modeling ◽  
Coupled Model ◽  
Ocean Model ◽  
Heat Fluxes ◽  
Naval Research ◽  
Modeling Framework ◽  
Ligurian Sea ◽  
In Situ Data ◽  
Ocean Atmosphere

Abstract In situ experimental data and numerical model results are presented for the Ligurian Sea in the northwestern Mediterranean. The Ligurian Sea Air–Sea Interaction Experiment (LASIE07) and LIGURE2007 experiments took place in June 2007. The LASIE07 and LIGURE2007 data are used to validate the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS)1 developed at the Naval Research Laboratory. This system includes an atmospheric sigma coordinate, nonhydrostatic model, coupled to a hydrostatic sigma-z-level ocean model (Navy Coastal Ocean Model), using the Earth System Modeling Framework (ESMF). A month-long simulation, which includes data assimilation in the atmosphere and full coupling, is compared against an uncoupled run where analysis SST is used for computation of the bulk fluxes. This reveals that COAMPS has reasonable skill in predicting the wind stress and surface heat fluxes at LASIE07 mooring locations in shallow and deep water. At the LASIE07 coastal site (but not at the deep site) the validation shows that the coupled model has a much smaller bias in latent heat flux, because of improvements in the SST field relative to the uncoupled model. This in turn leads to large differences in upper-ocean temperature between the coupled model and an uncoupled ocean model run.

scholarly journals Phytoplankton Phenology in the Coastal Zone of Cyprus, Based on Remote Sensing and In Situ Observations

2021 ◽  
Vol 14 (1) ◽  
pp. 12
Author(s):  
Monica Demetriou ◽  
Dionysios E. Raitsos ◽  
Antonia Kournopoulou ◽  
Manolis Mandalakis ◽  
Spyros Sfenthourakis ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Phytoplankton Biomass ◽  
Trophic Levels ◽  
Data Availability ◽  
Ocean Colour ◽  
Chl A ◽  
In Situ Data

Alterations in phytoplankton biomass, community structure and timing of their growth (phenology), are directly implicated in the carbon cycle and energy transfer to higher trophic levels of the marine food web. Due to the lack of long-term in situ datasets, there is very little information on phytoplankton seasonal succession in Cyprus (eastern Mediterranean Sea). On the other hand, satellite-derived measurements of ocean colour can only provide long-term time series of chlorophyll (an index of phytoplankton biomass) up to the first optical depth (surface waters). The coupling of both means of observations is essential for understanding phytoplankton dynamics and their response to environmental change. Here, we use 23 years of remotely sensed, regionally tuned ocean-colour observations, along with a unique time series of in situ phytoplankton pigment composition data, collected in coastal waters of Cyprus during 2016. The satellite observations show an initiation of phytoplankton growth period in November, a peak in February and termination in April, with an overall mean duration of ~4 months. An in-depth exploration of in situ total Chl-a concentration and phytoplankton pigments revealed that pico- and nano-plankton cells dominated the phytoplankton community. The growth peak in February was dominated by nanophytoplankton and potentially larger diatoms (pigments of 19’ hexanoyloxyfucoxanthin and fucoxanthin, respectively), in the 0–20 m layer. The highest total Chl-a concentration was recorded at a station off Akrotiri peninsula in the south, where strong coastal upwelling has been reported. Another station in the southern part, located next to a fish farm, showed a higher contribution of picophytoplankton during the most oligotrophic period (summer). Our results highlight the importance of using available in situ data coupled to ocean-colour remote sensing, for monitoring marine ecosystems in areas with limited in situ data availability.

scholarly journals A Generalization of the TRIX trophic index to the Adriatic Sea basin

2016 ◽  
Author(s):  
Emanuela Fiori ◽  
Marco Zavatarelli ◽  
Nadia Pinardi ◽  
Cristina Mazziotti ◽  
Carla Rita Ferrari
Keyword(s):  
Time Series ◽  
Adriatic Sea ◽  
Simulated Data ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
In Situ Data ◽  
Trophic Index ◽  
Scaling Parameters ◽  
Italian Legislation

Abstract. The Marine Strategy Framework Directive is pushing for new methodological approaches in order to protect the marine environment more effectively. The trophic index TRIX was developed by Vollenweider in 1998 for the coastal area of Emilia-Romagna (northern Adriatic Sea), and was exploited by Italian legislation to characterize the trophic state of coastal waters. In order to implement TRIX in different areas and for different time periods, we developed a methodology for the generalization of the index changing the scaling parameters. We compared the TRIX index calculated from in situ data ("in situ TRIX") with the corresponding index simulated with a coupled physics and biogeochemical numerical model ("model TRIX") implemented in the overall Adriatic Sea. The comparison between in situ and simulated data was carried out for a data time series in the Emilia-Romagna coastal strip. This study demonstrates the compatibility of the model with the in situ TRIX and the necessity to have time series longer than 10 years to evaluate properly the scaling parameters. The model TRIX is finally calculated for the whole Adriatic Sea showing trophic index differences across the Adriatic coastal areas.

scholarly journals Characterizing upper-ocean mixing and its effect on the spring phytoplankton bloom with in situ data

2015 ◽  
Vol 72 (6) ◽  
pp. 1961-1970 ◽  
Author(s):  
Sarah R. Brody ◽  
M. Susan Lozier
Keyword(s):  
Mixed Layer ◽  
Spring Bloom ◽  
Phytoplankton Bloom ◽  
Upper Ocean ◽  
Late Winter ◽  
Uniform Density ◽  
Spring Phytoplankton Bloom ◽  
In Situ Data ◽  
Active Mixing

Abstract Since publication, the Sverdrup hypothesis, that phytoplankton are uniformly distributed within the ocean mixed layer and bloom once the ocean warms and stratifies in spring, has been the conventional explanation of subpolar phytoplankton spring bloom initiation. Recent studies have sought to differentiate between the actively mixing section of the upper ocean and the uniform-density mixed layer, arguing, as Sverdrup implied, that decreases in active mixing drive the spring bloom. In this study, we use in situ data to investigate the characteristics and depth of active mixing in both buoyancy- and wind-driven regimes and explore the idea that the shift from buoyancy-driven to wind-driven mixing in the late winter or early spring creates the conditions necessary for blooms to begin. We identify the bloom initiation based on net rates of biomass accumulation and relate changes in the depth of active mixing to changes in biomass depth profiles. These analyses support the idea that decreases in the depth of active mixing, a result of the transition from buoyancy-driven to wind-driven mixing, control the timing of the spring bloom.

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