Model Challenges, Synergies, and Intercomparisons Curchitser Beardsley Batchelder Brown Coyle Hofmann Leising Phinney Ruzicka Teo Wikle

Model Challenges, Synergies, and Intercomparisons (19 Feb 2009) ‏ Co-chairs: Enrique Curchitser, Bob Beardsley Rapporteur: Hal Batchelder WG Participants: Ken Coyle, Cabell Davis (part), Andy Leising, Mike Alexander, Jerome Fiechter (part), Avijit Gangopadhyay (part), Jim Ruzicka, Steve Teo Charge to Working Group: Discuss WG title issues in context of past work, present needs and future opportunities. In particular are there unrealized opportunities to extend the existing Pan Regional projects through incremental changes and/or cross-project synergies that will improve the quality and/or value of GLOBEC synthesis?

Challenges (C) -- Part 1 C1) developing skillful models that simulate basic observed patterns, such as onshore-offshore gradients, vertical structure, and seasonal cycles in both biology and physics C2) Can Eulerian (NPZ+) ecosystem models replicate the changes observed in known regimes? We sell model abilities to forecast future ecosystems in changed climates? But have we demonstrated adequately that the existing models can reproduce directions/magnitude of changes across known regime shifts or other significant environmental perturbations (ENSO)? C3) development of better external forcing for ocean models: -winds: (mesoscale model) vs. NCEP vs. ECMWF vs. CORE vs. other -freshwater: need better freshwater bc's and terrestrial runoffs (because of its importance to stratification and other processes) ‏ -radiation

Challenges (C) - Part 2 C4) how do we couple higher trophic levels (fish, etc.) to LTL models; difficult to link annual-scale equilibrium upper trophic models with daily-scale (dynamic) LTL models C5) State measurements alone are insufficient for developing ecosystem models. At least one rate measurement must be obtained to constrain the model dynamics—e.g., phytoplankton primary production or dilution experiments (get both growth and uZ grazing rates).

Challenges (C) - Part 3 C6) What is required of physical models for biology? Be nice to get the MLD correct, because of the critical role of MLD in nutrient fluxes and subsequent biological processes. GLOBEC modeling-data comparisons revealed the importance of assimilation of in situ data to getting accurate state predictions and dynamics. An example from Georges Bank bottom dye experiment and FVCOM simulations suggested that increased (50-70m) horizontal resolution alone was insufficient to correctly simulate observed cross-frontal exchanges in boundary layer. Assimilation is needed to correctly simulate dye movements. Similar results known for simulating non- topographically locked eddy locations in coastal flows. C7) Need biological boundary conditions for regional models in order to evaluate interannual variability in ecosystems. Climatological BC's insufficient if the goal is to understand present and future climate variability impacts on ecological dynamics.

Synergies (S) ‏ S1) E2E project would like to interface with the BHM project to aid parameterization S2) GLOBEC has traditionally focused on target species, but E2E is now modeling much more than GLOBEC studied, so there are substantial data gaps. There are some subtle issues, such as shifts in zooplankton species composition, that significantly impact larval fish feeding, that might not be readily accomodated in E2E models.

Intercomparisons/Best Practices (I) ‏ I1) impacts of model resolution on physical and biological skill I2) Calanus requires dormancy sophistication, and evaluation of multiple approaches I3) intercomparisons of biological and physical models is fundamentally different; biological model intercomparisons should focus on either common functions or common currency, such as estimates of primary production I4) Intercomparisons of forcing data sets. ECMWF and NCEP are not designed to force ocean models, they are descriptions of climatologies. There are few products appropriate for forcing regional ocean models.

Other Tasks or Discussion Topics (O) – Part 1 O1) Catalog ecosystem and physical models and their evolution; identifying causes of changes; physical models have most often changed due to increased computing power; biological models have changed due to increased understanding/information. O2) Modeling of benthos is essential for some ecosystems; perhaps not for others O3) We discussed intercomparing various IBM model formulations, but did not reach consensus about how to accomplish this. O4) Encourage stronger interactions of coastal modeling community and CLIVAR

Other Tasks or Discussion Topics (O) – Part 2 O5) Interactions between modelers and observationists could be better and more bi-directional, particularly when physical models have poor skill on important features—may lead to identification of specific observations that may be needed for assimilation to enhance model skill. O6) related to the FW BCs and treatments, there was a general discussion about improvements being made in land use models in climate modeling, which might lead to improved FW fluxes to oceans.

Is that it? GLOBEC has fostered a new interdisciplinary mindset to coastal oceanography, linking physical, biological and fisheries ocean scientists (data collectors and modelers both) in regional programs from the initial planning stages, through implementation and execution to synthesis. This integration of disciplines was critical to the success of GLOBEC (much more so than in WOCE and JGOFS) and is apparently contagious (e.g., CAMEO, IMBER, etc.). Moreover, many graduate students and post-docs have been part of GLOBEC studies, and have been trained in the art of the Jedi Warrior (I mean GLOBEC scientist). These are the interdisciplinary scientists that will be developing future science programs and training future students. Models & Data