Data assimilation in a coupled physical–biogeochemical model of the California Current System using an incremental lognormal 4-dimensional variational approach: Part 1—Model formulation and biological data assimilation twin experiments

Song, Hajoon; Edwards, Christopher A.; Moore, Andrew M.; Fiechter, Jérôme

doi:10.1016/j.ocemod.2016.04.001

Cited by 22 publications

(12 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Data assimilative methods to produce reliable, data-constrained biological variables from ocean models are less mature than their physical counterparts, but in active development. Gregg [84] and Edwards et al [20] provide reviews of oceanographic biological assimilation efforts and Song et al [85][86][87] apply the present 4D-Variational assimilative methodology to biological variables in the California Current System. Experimental efforts to produce near real-time chlorophyll estimates are underway also.…”

Section: Discussionmentioning

confidence: 99%

Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions?

et al. 2016

View full text Add to dashboard Cite

Species distribution models are now widely used in conservation and management to predict suitable habitat for protected marine species. The primary sources of dynamic habitat data have been in situ and remotely sensed oceanic variables (both are considered "measured data"), but now ocean models can provide historical estimates and forecast predictions of relevant habitat variables such as temperature, salinity, and mixed layer depth. To assess the performance of modeled ocean data in species distribution models, we present a case study for cetaceans that compares models based on output from a data assimilative implementation of the Regional Ocean Modeling System (ROMS) to those based on measured data. Specifically, we used seven years of cetacean line-transect survey data collected between 1991 and 2009 to develop predictive habitat-based models of cetacean density for 11 species in the California Current Ecosystem. Two different generalized additive models were compared: one built with a full suite of ROMS output and another built with a full suite of measured data. Model performance was assessed using the percentage of explained deviance, root mean squared error (RMSE), observed to predicted density ratios, and visual inspection of predicted and observed distributions. Predicted distribution patterns were similar for models using ROMS output and measured data, and showed good concordance between observed sightings and model predictions. Quantitative measures of predictive ability were also similar between model types, and RMSE values were almost identical. The overall demonstrated success of the ROMS-based models opens new opportunities for dynamic species management and biodiversity monitoring because ROMS output is available in near real time and can be forecast.

show abstract

Section: Discussionmentioning

confidence: 99%

Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions?

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Positive residuals are weighted higher than negative ones, even when relative errors are equal. There could be some improvement to the posterior emissions by implementing the incremental log-normal methods of Fletcher and Jones (2014) or Song et al (2016). If the purpose of the inventory is to provide air quality warnings to the major California cities, then FINNv1.0, FINNv1.5, and QFEDv2.4r8 all have some builtin high bias that will err on the side of caution.…”

Section: Discussionmentioning

confidence: 99%

“…(10). Two alternatives to our approach that include log-normal observations are proposed by Fletcher and Jones (2014), who introduced a geometric incremental formulation with a nonquadratic cost function, and Song et al (2016), who devised a quadratic approximation to the additive incremental lognormal cost function.…”

Section: Log-normal Control Variablesmentioning

confidence: 99%

Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

Guerrette

Henze

2017

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental four-dimensional variational (4D-Var) capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB) and anthropogenic black carbon (BC) aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB) field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network on 22, 23, and 24 June 2008. We consider three BB inventories, including Fire INventory from NCAR (FINN) v1.0 and v1.5 and Quick Fire Emissions Database (QFED) v2.4r8. On 22 June, aircraft observations are able to reduce the spread between a customized QFED inventory and FINNv1.0 from a factor of 3.5 (×3.5) to only ×2.1. On 23 and 24 June, the spread is reduced from ×3.4 to ×1.4. The posterior corrections to emissions are heterogeneous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The US EPA's 2005 National Emissions Inventory (NEI05) is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is reduced by ×2, where highway sources dominate, while inland sources are increased near Barstow by ×5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and by up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly limited to sources close to observations. We find that the 22 June aircraft observations are able to constrain approximately 14 degrees of freedom of signal (DOF), while surface and aircraft observations together on 23/24 June constrain 23 DOF. Improving hourly-to daily-scale concentration predictions of BC and other aerosols during BB events will require more comprehensive and/or targeted measurements and a more complete accounting of sources of error besides the emissions.

show abstract

“…Typical Gaussian observation errors of N(0, 2 cm) for SSH, N(0, 0.3 • C) for temperature (both SST and temperature profiles), and N (0, 0.01) for salinity are added to the sampled data. SSH and SST are sampled weekly at every fifth horizontal grid point to yield a spatial resolution of ∼ 1/4 • as such an assimilation time window or spatial resolution has been adopted in previous realistic DA applications (e.g., weekly gridded product of SSH used in Moore et al, 2011, andSong et al, 2016b; weekly gridded product of SST in Hoteit et al, 2013). SSH in regions shallower than 300 m is not used for assimilation because dynamics in shelf areas where wind and buoyancy forcing dominate could substantially deviate from the geostrophic state, weakening the correlation between SSH and subsurface temperature and salinity fields.…”

Section: Nonidentical Twin Experimentsmentioning

confidence: 99%

“…The identical twin approach has been more commonly used in oceanic DA applications (e.g., Counillon and Bertino, 2009b;Simon and Bertino, 2009;Srinivasan et al, 2011;Song et al, 2016a;Yu et al, 2018a) although it is well known from atmospheric OSSEs that this approach provides biased impact assessments when the error growth rate between the truth and forecast runs is insufficient (e.g., Arnold and Dey, 1986;Atlas, 1997;Hoffman and Atlas, 2016). This fact is not yet sufficiently recognized in applications of ocean OSSEs and skill assessments of oceanic DA systems (Halliwell et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of nonidentical versus identical twin approaches for observation impact assessments: an ensemble-Kalman-filter-based ocean assimilation application for the Gulf of Mexico

Yu¹,

Fennel²,

Wang³

et al. 2019

Ocean Sci.

View full text Add to dashboard Cite

Abstract. Assessments of ocean data assimilation (DA) systems and observing system design experiments typically rely on identical or nonidentical twin experiments. The identical twin approach has been recognized as yielding biased impact assessments in atmospheric predictions, but these shortcomings are not sufficiently appreciated for oceanic DA applications. Here we present the first direct comparison of the nonidentical and identical twin approaches in an ocean DA application. We assess the assimilation impact for both approaches in a DA system for the Gulf of Mexico that uses the ensemble Kalman filter. Our comparisons show that, despite a reasonable error growth rate in both approaches, the identical twin produces a biased skill assessment, overestimating the improvement from assimilating sea surface height and sea surface temperature observations while underestimating the value of assimilating temperature and salinity profiles. Such biases can lead to an undervaluation of some observing assets (in this case profilers) and thus a misguided distribution of observing system investments.

show abstract

Data assimilation in a coupled physical–biogeochemical model of the California Current System using an incremental lognormal 4-dimensional variational approach: Part 1—Model formulation and biological data assimilation twin experiments

Cited by 22 publications

References 47 publications

Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions?

Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions?

Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

Evaluation of nonidentical versus identical twin approaches for observation impact assessments: an ensemble-Kalman-filter-based ocean assimilation application for the Gulf of Mexico

Contact Info

Product

Resources

About