Data assimilation in a coupled physical-biogeochemical model of the California current system using an incremental lognormal 4-dimensional variational approach: Part 3—Assimilation in a realistic context using satellite and in situ observations

2016 ◽  
Vol 106 ◽  
pp. 159-172 ◽  
Author(s):  
Hajoon Song ◽  
Christopher A. Edwards ◽  
Andrew M. Moore ◽  
Jerome Fiechter
Keyword(s):  
Data Assimilation ◽  
Variational Approach ◽  
Current System ◽  
California Current ◽  
Biogeochemical Model ◽  
California Current System ◽  
In Situ Observations

scholarly journals Zooglider-Based Measurements of Planktonic Foraminifera in the California Current System

2019 ◽  
Vol 49 (4) ◽  
pp. 390-404 ◽  
Author(s):  
Daniel E. Gaskell ◽  
Mark D. Ohman ◽  
Pincelli M. Hull
Keyword(s):  
Current System ◽  
Planktonic Foraminifera ◽  
California Current ◽  
Natural Disturbance ◽  
Spine Length ◽  
California Current System ◽  
Regular Source ◽  
La Jolla ◽  
Shell Geochemistry

Abstract Spines and rhizopodia play an important role in the feeding behavior, symbiont ecology, shell geochemistry, and density and drag of planktonic foraminifera. However, there are few empirical data on planktonic foraminifera in situ, and these delicate structures are disturbed on capture. Here, we report spine and rhizopod measurements from underwater images obtained in the California Current System near La Jolla, California by Zooglider, a new autonomous zooplankton-sensing glider. Across all observed species, we find that spine length and flexibility correlate with test size and that spines increase the effective prey encounter volume of spinose foraminifera by two to three orders of magnitude. Our data also yielded several novel observations regarding hastigerinid foraminifera (Hastigerinella digitata and Hastigerina pelagica), a group of unusually large planktonic foraminifera that are abundant in our dataset below 250 m. First, the effective encounter volume of hastigerinid foraminifera can be very large: our largest specimen occupies almost 40 cm3 (about the size of a golf ball), while the median specimen occupies 5.3 cm3 (about the size of a cherry). Second, the majority of hastigerinid foraminifera in our dataset have asymmetric bubble capsules, which are most frequently oriented with their bubbles on the upward side of the test, consistent with the hypothesis that the bubble capsule is positively buoyant. Third, 16% of hastigerinid foraminifera in our dataset have dispersed bubble capsules with detached bubbles distributed along the spines and rhizopodia, consistent with a regular source of natural disturbance. Taken together, our observations suggest that hastigerinid foraminifera play a larger role as mesopelagic predators in the California Current System than previously recognized.

Data assimilation of physical and chlorophyll a observations in the California Current System using two biogeochemical models

2017 ◽  
Vol 109 ◽  
pp. 55-71 ◽  
Author(s):  
Jann Paul Mattern ◽  
Hajoon Song ◽  
Christopher A. Edwards ◽  
Andrew M. Moore ◽  
Jerome Fiechter
Keyword(s):  
Data Assimilation ◽  
Chlorophyll A ◽  
Current System ◽  
California Current ◽  
California Current System ◽  
Biogeochemical Models

Application of 4D-Variational data assimilation to the California Current System

2009 ◽  
Vol 48 (1-3) ◽  
pp. 69-92 ◽  
Author(s):  
G. Broquet ◽  
C.A. Edwards ◽  
A.M. Moore ◽  
B.S. Powell ◽  
M. Veneziani ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Current System ◽  
California Current ◽  
Variational Data Assimilation ◽  
California Current System

scholarly journals Ocean Front Detection with Glider and Satellite-Derived SST Data in the Southern California Current System

2021 ◽  
Vol 13 (24) ◽  
pp. 5032
Author(s):  
Frank C. Olaya ◽  
Reginaldo Durazo ◽  
Vera Oerder ◽  
Enric Pallàs-Sanz ◽  
Joaquim P. Bento
Keyword(s):  
Significant Contribution ◽  
Current System ◽  
California Current ◽  
California Current System ◽  
Ocean Fronts ◽  
Multi Scale ◽  
Highly Correlated ◽  
Processing Techniques ◽  
Front Detection

This study proposes a method to detect ocean fronts from in situ temperature and density glider measurements. This method is applied to data collected along the CalCOFI Line 90, south of the California Current System (CCS), over the 2006–2013 period. It is based on image-processing techniques commonly applied to sea surface temperature (SST) satellite data. Front detection results using glider data are consistent with those obtained in other studies carried out in the CCS. SST images of the Multi-scale Ultra-high Resolution (MUR) dataset were also used to compare the probability of occurrence or front frequency (FF) obtained with the two datasets. Glider and MUR temperatures are highly correlated. Along Line 90, frontal frequency exhibited the same maxima near the transition zone (~130 km offshore) as derived from MUR and glider datasets. However, marked differences were found in the bimonthly FF probability with high (low) front frequency in spring-summer for glider (MUR) data. Methodological differences explaining these contrasting results are investigated. Thermohaline-compensated fronts are more abundant towards the oceanic zone, although most fronts are detected using both temperature and density criteria, indicating a significant contribution of temperature to density in this region.

scholarly journals Weak constraint four-dimensional variational data assimilation in a model of the California Current System

2016 ◽  
Vol 2 (2) ◽  
pp. 171-192 ◽  
Author(s):  
William J. Crawford ◽  
Polly J. Smith ◽  
Ralph F. Milliff ◽  
Jerome Fiechter ◽  
Christopher K. Wikle ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Ocean Circulation ◽  
Hierarchical Modeling ◽  
Current System ◽  
California Current ◽  
Model Errors ◽  
Strong Constraint ◽  
California Current System ◽  
Twin Model ◽  
Error Covariance

Abstract. A new approach is explored for computing estimates of the error covariance associated with the intrinsic errors of a numerical forecast model in regions characterized by upwelling and downwelling. The approach used is based on a combination of strong constraint data assimilation, twin model experiments, linear inverse modeling, and Bayesian hierarchical modeling. The resulting model error covariance estimates Q are applied to a model of the California Current System using weak constraint four-dimensional variational (4D-Var) data assimilation to compute estimates of the ocean circulation. The results of this study show that the estimates of Q derived following our approach lead to demonstrable improvements in the model circulation estimates and isolate regions where model errors are likely to be important and that have been independently identified in the same model in previously published work.

scholarly journals A Dynamically Downscaled Ensemble of Future Projections for the California Current System

2021 ◽  
Vol 8 ◽  
Author(s):  
Mercedes Pozo Buil ◽  
Michael G. Jacox ◽  
Jerome Fiechter ◽  
Michael A. Alexander ◽  
Steven J. Bograd ◽  
...  
Keyword(s):  
Current System ◽  
California Current ◽  
Nitrate Content ◽  
Biogeochemical Model ◽  
Climate Projections ◽  
Surface Mixed Layer ◽  
California Current System ◽  
The Future ◽  
The Mean ◽  
Source Waters

Given the ecological and economic importance of eastern boundary upwelling systems like the California Current System (CCS), their evolution under climate change is of considerable interest for resource management. However, the spatial resolution of global earth system models (ESMs) is typically too coarse to properly resolve coastal winds and upwelling dynamics that are key to structuring these ecosystems. Here we use a high-resolution (0.1°) regional ocean circulation model coupled with a biogeochemical model to dynamically downscale ESMs and produce climate projections for the CCS under the high emission scenario, Representative Concentration Pathway 8.5. To capture model uncertainty in the projections, we downscale three ESMs: GFDL-ESM2M, HadGEM2-ES, and IPSL-CM5A-MR, which span the CMIP5 range for future changes in both the mean and variance of physical and biogeochemical CCS properties. The forcing of the regional ocean model is constructed with a “time-varying delta” method, which removes the mean bias of the ESM forcing and resolves the full transient ocean response from 1980 to 2100. We found that all models agree in the direction of the future change in offshore waters: an intensification of upwelling favorable winds in the northern CCS, an overall surface warming, and an enrichment of nitrate and corresponding decrease in dissolved oxygen below the surface mixed layer. However, differences in projections of these properties arise in the coastal region, producing different responses of the future biogeochemical variables. Two of the models display an increase of surface chlorophyll in the northern CCS, consistent with a combination of higher nitrate content in source waters and an intensification of upwelling favorable winds. All three models display a decrease of chlorophyll in the southern CCS, which appears to be driven by decreased upwelling favorable winds and enhanced stratification, and, for the HadGEM2-ES forced run, decreased nitrate content in upwelling source waters in nearshore regions. While trends in the downscaled models reflect those in the ESMs that force them, the ESM and downscaled solutions differ more for biogeochemical than for physical variables.

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