Estuarine Hypoxia Progress Report
for
June – August 2011
September 21, 2011
Marjorie Friedrichs
Estuarine Hypoxia Team Lead
1 Accomplishments
1.1 New models
1.2 New hindcasts
1.3 New sensitivity studies
1.4 New skill assessment results
1.5 Modular modeling progress (CSDMS)
2 Workshops
3 Papers
4 Presentations
5 Mature elements of modeling/skill assessment
6 Future Challenges
1. Accomplishments
There have been substantial accomplishments by the EH Team members
throughout June-August 2011, which include the development of new models,
new hindcast simulations, new sensitivity studies and new skill assessment
results, as described below.
1.1 Development of new models for the Chesapeake Bay
One remaining issue for the EH team is that all of our models currently being
compared are using structured grids. In order to look at the effect of structured vs.
unstructured grids, team member Jian Shen has been developing the semiimplicit Eulerian-Lagrangian finite element SELFE model for the Chesapeake
Bay. He tested three approaches using different model grids: (1) fully
unstructured grid, (2) structured grid, which is identical to EFDC, and (3)
combined structured and unstructured grid. Model tests showed that salinity is
better simulated using a combined structured and unstructured grid approach.
The current model grid has a total of 22,095 cells in the horizontal with 20 vertical
layers. He used structured grids for the main channel, which is similar to the
EFDC model grids, and used unstructured grids for sallow area and tributaries.
The model was calibrated for surface elevation and salinity. The tidal open
boundary, fresh water, salinity open boundary, and wind forcing are identical to
the EFDC model. Jian Shen tested model simulation using both sigma and scoordinate and different turbulent schemes. The best model performance was
obtained using the sigma and k- psilon model. In future months the skill of this
model will be tested against the skill of the other CB hydrodynamic models
currently participating in the testbed framework.
1.2 Newly available hindcasts
Wen Long has further advanced the ChesROMS biogeochemical modeling
efforts by means of tuning various parameters including detritus pool
remineralization rates, river loading estimate of detritus and DON, as well as
surface and diffusive fluxes of NO3 and NH4. A four-year biogeochemical model
simulation (2007 to 2010) has now been completed using the ChesROMS
operational model suite with its nowcasting/re-nowcasting capability. The model
configuration and forcing as well as results are now available at:
http://131.118.211.30/chesroms-renowcast-2007-2010/. Analyses of these
results are underway for publication of a paper regarding empirical habitat
prediction of harmful algae Karlodinium veneficum as well as a paper describing
the overall performance of ChesROMS operational modeling. These model tests
will be shared throughout the SURA super testbed project team to facilitate
collaboration.
Malcolm Scully has recently conducted a 15-year simulation (1991-2005) with the
goal of examining the importance of inter-annual changes in physical forcing on
the results of the simple 1-term oxygen model for Chesapeake Bay in
ChesROMS.
1.3 New skill assessment comparisons
Over the past few months there has been significant progress on the assessment
of model skill in terms of both hydrodynamics and dissolved oxygen in
Chesapeake Bay. We unfortunately found out that the CH3D output we had been
using was incorrect, and thus all our comparisons were redone with the corrected
output – although the changes for 2004 were minor. The primary change was
that CH3D performs significantly better in 2005 than it did in our initial analyses.
Further analyses by Aaron Bever and Marjy Friedrichs have indicated that all the
models perform significantly better in 2005 than in 2004, leading us to the
conclusion that we should actually be looking at skill for more than just two years.
We have now requested that some of the models provide a 20-year simulation,
so we can get a better feeling for how the various models perform on an
interannual basis. It is possible that some models are tuned to perform well
during 2004/2005, but they may not be able to get the interannual/interdecadal
trends that are an important aspect of climate change in the Bay.
In terms of the MAB hydrodynamic model comparisons, John Wilkin and Julia
Levin continue to work on depicting metrics (i.e. Taylor diagrams) for vector time
series, and applying these to comparing ESPreSSO, NCOM, HyCOM, COAWST,
UMassHOPS, NYHOPS and Mercator to CODAR in the MAB.
1.4 New sensitivity studies
The EH team continues to examine not only which models perform best, but also
why certain models perform better than others. To address this ‘why’ question,
sensitivity studies are continually being conducted. For example, Wen Long has
recently conducted studies on the sensitivity of Chesapeake Bay salinity
structure in response to mid-Atlantic shelf forcing and river flow based on year
2005 retrospective simulation using ChesROMS. The tests conducted include
perturbations in forcing conditions such as open ocean T and S, shelf wind speed
and river discharge relative to the baseline case of 2005. Results show that
salinity budget and stratification structure (using EOF analysis) in the Bay are
much more responsive to perturbations in river discharge than to open boundary
T, S and shelf wind speed. Further sensitivity tests based on perturbations to
shelf wind direction, open boundary sea surface height, as well as the turbulence
scheme parameter GLS_Kmin (minimum tke) have been conducted and analysis
of results are pending the completion of the run.
Malcolm Scully has also performed sensitivity analyses on the importance of
physical forcing on hypoxic volume in Chesapeake Bay including sensitivity to
forcings such as river discharge, wind speed and water temperature. In addition,
he has performed sensitivity analyses on the importance of turbulence closure
parameterizations for predictions of hypoxia.
1.5 Modular modeling progress
Scott Peckham continues to work with other team members, such as Wen Long,
in an effort to implement multiple Chesapeake Bay ROMS grids on a communityaccessible single HPC system, so that a wider community will be able to easily
experiment with the ChesROMS modeling framework.
2. Workshops
2.1 Chesapeake Bay Hydrodynamics Modeling Workshop, June 9-10, 2011,
Edgewater, MD
Multiple members of the EH team (M. Friedrichs, C. Friedrichs, K. Sellner, R.
Hood, W. Long) served as steering committee members for a workshop on
hydrodynamic modeling in the Chesapeake Bay, which was sponsored by the
EPA/NOAA Chesapeake Bay Program’s (CBP) Scientific and Technical Advisory
Committee (STAC) and the Chesapeake Community Modeling Program. The
workshop included overview talks on hydrodynamic model comparisons, as well
as presentations on specific hydrodynamic models that the CBP could consider
as alternatives or supplements to the existing CBP model. Talks on the
sensitivities of these models to coastal boundary conditions and turbulence
closure schemes were included on Day 2. At the conclusion of the workshop, the
steering committee identified five recommendations for future hydrodynamical
modeling efforts focusing on the Chesapeake Bay:
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Use multiple models
Use open source community models
Assess model skill
Implement models in a modular fashion
Form a Chesapeake Modeling Laboratory to enable the above
These will be provided to the CBP in a letter from STAC in the coming weeks. A
response from CBP is required within 90 days from the receipt of this workshop
report.
2.2 2011 Chesapeake Bay Eco-Forecasting Workshop II: Research to
Applications
The objectives of this workshop, organized by David Green (NWS), Doug Wilson
(NOS/NCBO) and Chris Brown (NESDIS/STAR) were to provide an update on
the transition to operation of prototype forecast products and services and share
the latest developments in the design, implementation, use, and evaluation of
end-to-end ecological forecast capabilities, partnerships, and infrastructure for
the Chesapeake Bay and other regions. An additional goal was to identify
possible tactical approaches to operate and maintain a Chesapeake Bay
ecological forecasting system. The workshop started with a half-day session that
includes a number of brief presentations and discussions. This was intended to
build relationships and update participants with the state of mature research and
relevant service capabilities. The second day was a facilitated workshop for a
smaller and more specialized group of technical experts/stakeholders to explore
the operational framework and potential implementation plans. The second day
workshop aimed to identify potential activities, tasks and measures to move
forward as well as gaps and solutions relevant to operational ecological forecasts
for the Chesapeake Bay. The target is to transition regional pathfinder projects
with particular consideration given to hypoxia.
Our SURA testbed results were presented by Marjorie Friedrichs on Day 1, and
were highlighted in Day 2 as an example of an ecological forecast that would be
viable in the near future. A detailed plan for how to transition the CBOFS2 model
with the simple 1-term DO formulation into operations was discussed.
3. Papers
The EH team has multiple papers published or in preparation. These include:
Xu, J., W. Long, J. D. Wiggert, L. W. J. Lanerolle, C. W. Brown, R. Murtugudde
and R. R. Hood, Climate Forcing and Salinity Variability in Chesapeake Bay,
USA, Estuaries and Coasts DOI: 10.1007/s12237-011-9423-5, 2011
Bever, A., M.A.M. Friedrichs, C.T. Friedrichs, and M. Scully. Combining
observational and numerical model results to improve estimates of hypoxic
volume within the Chesapeake Bay, USA. To be submitted to Biogeosciences.
Scully, M.E., Physical controls on hypoxia in Chesapeake Bay: A numerical
modeling study, to be submitted to Estuaries and Coasts, October, 2011.
Friedrichs, M.A.M. and the EH testbed team. Skill assessment of DO models
within Chesapeake Bay. To be submitted to Biogeosciences.
Friedrichs, C.T., and the EH testbed team. Results of IOOS testbed for
comparison of hydrodynamic models of the Chesapeake Bay. To be submitted to
Estuarine and Coastal Modeling.
4. Presentations
In addition to the multiple presentations listed below, our team has submitted
multiple abstracts to the CERF meeting in November as well as the AMS meeting
in January. These will be listed specifically in the next progress report.
(Presenter*, invited presenter**)
19 Aug 2011, Woods Hole Oceanographic Institution, Coastal Ocean Fluid
Dynamics Laboratory Seminar, Woods Hole, MA. M.E. Scully**, “Physical
controls on hypoxia in Chesapeake Bay”.
17 July, Coastal Zone 2011, Panel Session on Model Testbeds Defining the
Goals, Chicago, IL. J. Harding**, C. Friedrichs, R. Luettich, R. Signell. “The role
of the SURA Testbed in the improvement of U.S. Coastal and Estuarine
Prediction”.
12 Jul 2011, EPA Chesapeake Bay Program, Modeling Team Quarterly Review
Meeting, Annapolis, MD. R. Hood**, D. Jasinski, K. Sellner, C. Friedrichs, C.
Cerco, M. Friedrichs, W. Long. “CCMP Hydrodynamic Modeling Workshop
report”.
5 Jul 2011, NOAA Chesapeake Bay Eco Forecasting Workshop II: Research to
Applications, Silver Springs, MD. M.A.M. Friedrichs**, A.J. Bever, C.T. Friedrichs,
Estuarine Hypoxia Testbed Team. “U.S. IOOS Testbed comparisons:
hydrodynamics and hypoxia”.
29 Jun 2011, Advances in Marine Ecosystem Modelling Research Symposium,
Plymouth, UK. A.J. Bever, M.A.M. Friedrichs**, C.T. Friedrichs. “Using
Chesapeake Bay models to develop informed observational sampling
strategies”.
26 Jun 2011, Gordon Conference on Coastal Ocean Modeling, South Hadley,
MA. A.J. Bever*, M.A.M. Friedrichs, C.T. Friedrichs. “Using Chesapeake Bay
models to develop informed observational sampling strategies”.
22 Jun 2011, U.S. IOOS Super-Regional Testbed Annual Meeting, SURA
Headquarters, Washington, DC. C.T. Friedrichs**, Estuarine Hypoxia Testbed
Team. Estuarine hypoxia modeling.
21 Jun 2011, SURA Coastal and Environmental Research Committee Meeting,
SURA Headquarters, Washington, DC. C.T. Friedrichs**, Estuarine Hypoxia
Testbed Team. “Estuarine hypoxia modeling in Chesapeake Bay”.
10 Jun 2011, Chesapeake Bay Hydrodynamical Modeling Workshop, Edgewater,
MD. M.E. Scully**, “Estuarine turbulence modeling”.
9 Jun 2011, Chesapeake Bay Hydrodynamical Modeling Workshop, Edgewater,
MD. A.J. Bever*, M.A.M. Friedrichs, C.T. Friedrichs. “Using Chesapeake Bay
models to develop informed observational sampling strategies”.
9 Jun 2011, Chesapeake Bay Hydrodynamical Modeling Workshop, Edgewater,
MD. M.A.M. Friedrichs**, A.J. Bever, C.T. Friedrichs, Estuarine Hypoxia Testbed
Team. “U.S. IOOS Testbed comparisons: hydrodynamics and hypoxia”.
5. Mature elements of modeling/skill assessment
Major results of the EH team include a demonstration that on seasonal time
scales these models all do well in capturing fundamental aspects of the
hydrodynamic and oxygen fields, although density stratification at the pycnocline
continues to be a universal challenge. Another significant finding with regards to
future modeling strategies is the result that the ensemble hindcast for dissolved
oxygen using multiple models was more accurate than the hindcast from any one
model.
Scientifically, important results to date include the ability of models with highly
simplified biology (e.g., a constant net respiration rate independent of nutrient
input) to reproduce the seasonal hypoxia cycle about as well as much more
complex, nutrient-dependent ecological models. Reproduction of seasonal
variation in DO was found to not be dependent on the seasonal cycle in
respiration rate, nor the seasonal cycle in fresh water input, nor the seasonal
cycle in density stratification. Rather, seasonal variation in DO was found to be
very sensitive to seasonal variations in wind speed and direction, likely due to
wind-induced lateral upwelling of hypoxic areas rather than local wind-induced
mixing.
The EH Team has also made very important progress in transitioning its model
formulations and scientific insights for use by Federal Agencies. For example,
Lyon Lanerolle, a modeler at NOAA-CSDL and a member of the Estuarine
Hypoxia Team, has already incorporated within the research version of NOAACSDL's Chesapeake Bay Operational Forecast System (CBOFS) a promising
hypoxia formulation developed by the IOOS/SURA Estuarine Hypoxia Team.
Marjorie Friedrichs was invited to attend a meeting between lead PIs on the
Estuarine Hypoxia Team and NOAA operational forecasters on July 5-6, 2011, at
NOAA-NCEP. The goal of this meeting was to further hammer out transition
steps for moving a fully operational version of the CBOFS model, including
hypoxia, to NCEP.
Members of the EH Team also helped organize a workshop funded by the
Scientific and Technical Advisory Committee (STAC) of the Chesapeake Bay
Program (CBP) on June 9-10, 2011, to provide advice to the CBP on future
estuarine hydrodynamic and hypoxia modeling strategies in support of Federally
mandated environmental restoration. As well as SURA/IOOS and EPA modelers,
the meeting included modelers from NOAA-CDSL, NOAA-NCEP, USGS and
USACE. At the meeting it was proposed that the SURA/IOOS Estuarine Hypoxia
Team play a lead role in helping to establish a framework for a new Chesapeake
Modeling Laboratory for developing and testing agency models. A Chesapeake
Modeling Laboratory was explicitly recommended as part of a National Academy
of Sciences report commission by EPA and released in May 2011 entitled
“Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An
Evaluation of Program Strategies and Implementation”. The workshop report
from this meeting has been delivered to STAC and will soon be passed along to
the CBP who will be required to respond to the recommendations provided.
6. Future challenges
Unstructured grids: To date, we have only analyzed and compared the results
of models developed to use structured grids. Progress on the implementation of
SELFE using both unstructured and structured grids is well underway, however it
will be a challenge to incorporate these results into our final skill assessment
analyses before the end of the NCE in December 2011.
Transition to operations: This fall we will be continuing to work closely with
NOAA-CSDL and NOAA-NCEP to continue the transition of our findings to use in
hypoxia forecasts at NOAA, however a significant remaining challenge on this
front is that to date we have only looked at the ability of our models to reproduce
the seasonal cycle of hypoxia in the Bay, whereas the NOAA is particularly
interested in short-term (< 10 day) forecasts. In the future we would like to be
able to test our models to see if they have any skill in reproducing DO
observations on shorter (< 1 month) time scales.
Peer-reviewed publications: We will continue to work on communicating and
publishing our results to the larger scientific community. We have been very
successful in presenting our results to EPA/NOAA/CBP managers through
presentations at multiple venues, but we are still working on getting our results
out into the peer-reviewed literature. This process takes time, and will not be
complete by the end of our NCE.
Interannual/interdecadal model skill: We are very interested to see if the
success of our simple 1-term DO formulation will hold on longer time scales. So
far we have demonstrated that this model has significant skill in reproducing the
seasonal variability of the DO signal in the Chesapeake Bay, however it is not
clear yet whether this model is capable of reproducing longer-term trends, or
whether its success is based on tuning to the years being analyzed (2004 and
2005). We currently have 20-year simulations in hand for CH3D, ChesROMS+1term DO and ChesROMS+NPZD, and we would like to compare the ability of
these models to reproduce longer term changes in hypoxic volume within the Bay,
however the analyses of these results will not be complete by the conclusion of
our NCE.