Phenomena and Observing System (POS) Panel

1. Possible Relevant Scientific Topics within US-CLIVAR • Phenomena and Observing System (POS) Panel • Ocean heat transport in eastern tropical basins (tracers would help resolve) • Coastal upwelling (importance of local forcing and processes of water transport) • More sophisticated biogeochemical model requirements for verification • Process Studies and Model Improvement Panel (PSMIP) • Air-sea interactions • Mesoscale ocean mixing • Southern Ocean and dynamics of atmosphere, ocean mixing and carbon uptake • Predictability, Prediction and Applications Interface (PPAI) Panel • Global general circulation and carbon uptake • Air-sea exchange and ocean mixing • Using biological system indicators

2. Global Observation Capabilities (Scott Doney) • Observations can constrain climate sensitivity to carbon forcing and carbon cycle sensitivity to changes in climate • Observing systems: • Repeat Hydrography (example of effective international collab) • - Tracers • - VOS measurements • - Moored arrays • - Profiling floats w/ Oxygen, Nitrate, bio-optics • Gliders • Satellite remote sensing of ocean color, SST, SSH, winds • Needs: • - Methods and best practices to address incomplete coverage and distribution of biogeochemical and physical measurements • systematic approach to profiling float deployment (suggestion to base on analyses of physical drivers) • address holes in pCO2 measurements by VOS tracks and N-S repeat lines (require higher frequency than every 10 yrs) • deep ocean measurements of physical and biogeochemical variables (6000m depth profiling floats being developed) • land/ocean boundary measurements to examine physics and address significant modeling errors/uncertainties • - Collaboration between GEOTRACES and CLIVAR • - Synthesized data sets with error estimates (funding required) • Studies of systematic biases of atmospheric CO2 fluxes; lack data to • examine importance of boundary layer stability • - Review of how errors in atmospheric reanalyses propagate into biogeochemistry analyses

3. Global Modeling Challenges & Opportunities (Mick Follows) • Do we understand the Earth system well enough to develop models that can effectively simulate climate over seasonal to interglacial timescales? • Major modeling challenge to bridge significantly disparate scales • - physical scales from molecular diffusion to global overturning • biogeochemical scales from intra-cellular metabolic networks to global biogeography • Understanding small scale processes necessary to develop parameterizations for climate modeling • Characterizing and quantifying “traits and trade-offs” at the scale of individuals is a critical step in advancing “trait-based” representations of marine ecosystems and biogeochemical cycles • Microbes are implicated for efficiency of recycling, export and storage of carbon; fitness and population of microbial communities determined by both physical and biological inputs • Genomic and molecular approaches provide information at the cellular scale, but parameterization is necessary for global climate scale studies • Discussion • Considerations of biological modeling • Gene information will help establish geography of carbon sources • Instead of focusing on individual species, recommendation to focus on collection of functional groups to build biogeochemical models • A key link between physical and biogeochemical modeling is in the resolution of space and time scales • Importance of mixing parameterizations for upwelling of nutrients • Land-ocean boundaries in physical ocean modeling represent a • difficult challenge; ultra-high resolution and nested approaches being • applied

4. Overturning Circulation Impacts (Alison Macdonald) • Review of global zonal integrated estimates of overturning (cross-isopycnal flow) in Atlantic and Pacific basins • Heat transport depends on both vertical and horizontal temperature differences • Impacts of overturning on Carbon including interaction of timescales • Discussion • Centennial scale problem has link to biological scales which feed back to centennial scales • Link between overturning and biology in space/time • Weak link on OCB side is observing system; don’t have resolution beyond satellite in the SO.

5. Carbon as Velcro – Connecting Physical Climate Variability and Biogeochemical Dynamics in the Southern Ocean (Nikki Lovenduski) • Mean State • Establishing the size of the SO CO2 sink • Explaining the strong spread of IPCC modeled cumulative anthropogenic CO2 uptake in SO (physics and ecology) • Role of eddies in CO2 uptake and transport • Variability • Determining how eddies respond to increasing wind stress • Observational needs for physical circulation, CO2 fluxes and storage, and ecology • Future Changes • Impacts of stratification of SO on carbon storage and ecology • Wind driven circulation changes and impacts on carbon and ecology • Pace of SO acidification • Discussion • Data needed to constrain models • Impact of atmospheric model choice to force the ocean model and frequency of forcing • Impact of using coupled ocean-sea ice model; sea ice expected to respond to ocean interactions; increase in ice will impact biology • Lack of understanding if ACC follows the wind or is locked to topography

6. Coupled Air-Sea Interaction and Variability in Ocean Biogeochemistry (Curtis Deutsch) • Case studies in carbon and oxygen cycles of the tropical Pacific which, based on empirical relationships, accounts for the largest fraction of global ocean CO2 variability • Review of El Nino and CO2 flux drivers, impact of shifting ENSO frequency, future climate (weakening Walker cell) and CO2outgasing and uptake • Mechanisms of O2 variability (thermocline depth variations), future climate and ocean hypoxia/anoxia • Climate warming is predicted to cause a slowdown of CO2 uptake and a “deoxygenation” of the ocean • Discussion • Can use profiling floats to directly measure seasonal cycle of O2 • - For which processes, and at which time scales, is natural variability in carbon cycle a useful analogue of long-term trends? (Where are amplitudes likely correlated across time scales?) • - What are the observational requirements to narrow the intermodel range at the shorter time scales (e.g. seasonal cycle to interannual variability)? • Do we need a coordinated effort to analyze the upcoming IPCC archive in these ways?

7. Sub-daily to Seasonal and Sub-Mesoscale to Mesoscale Processes and Interaction with Ocean Biology (AmalaMahadevan) • Observation and model based examination of relative roles of physical and biological processes underlying spatial variability of phytoplankton and occurrence of blooms in: • Subtropical gyres – physical processes dominate with lateral mesoscale eddy mixing and sub-mesoscale nutrient upwelling • Subpolar gyres – biological processes dominate with eddy-induced restratification and shoaling of mixed layer and higher average light • Coastal margins – both contribute with strong upwelling of nutrients and rapid lateral advection in sub-mesoscalefilaments • Importance of representing sub-mesoscale processes in coupled climate-biogeochemical models to understand basin-scale productivity • Discussion • - Concern on increasing resolution by order of magnitude-could impact hydrostatic balance • - Sub-mesoscale impacts of biological processes on temperature – not examined on shorter timescales • - Limitations of high resolution modeling for mixing; limitations of observations for high vertical velocity events

8. US CLIVAR Benefits from OCB Collaboration • Ocean Observations • Quantify size of sink, constrain carbon cycle in ocean models • Importance of biogeochemical tracers for constraining modeled ocean circulation; are they better (more easily measured, more discrete) than physical measurements? • Model development and analysis • Need for and limits of increased model resolution • Processes and observational constraints • Coupled Model Prediction • Impact of time-varying carbon and biogeochemical cycling on climate prediction; how do uncertainties in biogeochemical modeling impact climate prediction? • Impact of DMS aerosols on variability and change • Impact of biomass on ocean temperature Sarmiento presenting at 4:45pm in PSMI Panel on ‘Proposal for a Southern Ocean Biogeochemical Observations and Modeling (SOBOM) Program’ Would be good for POS Panel members to attend.