1. The ChesROMS Community Model
Raleigh Hood, Wen Long, Jiangtao Xu, Jerry Wiggert,
Lyon Lanerolle, and Christopher Brown
Funded by the NOAA Ecological Forecasting and MERHAB programs

2. Motivation:
Provide T, S and biogeochemical forcing for empirical Sea Nettle, HAB and pathogen nowcasts and short-term forecasts that we are generating as part of our NOAA funded projects.
Provide nowcasts and short-term forecasts of 3D hydrodynamic circulation, temperature and salinity, sediment transport, and biogeochemical properties for research, management and public uses in Chesapeake Bay.

3. ChesROMS Grid and Implementation
(chief architects, Dr. Jiangtao Xu and Dr. Wen Long)
Chesapeake Bay
implementation of ROMS
Curvilinear horizontal grid
Horizontal Grid (100 * 150)
Includes all major tributaries
Diffuse freshwater inputs estimated
C and D canal: treated as a river
Hindcast and operational
implementations

4. ChesROMS Grid and Implementation
Sigma-coordinate
vertically
20 levels
Increased resolution at
surface and bottom
boundaries
Turbulence closure: κ-ω

5. ChesROMS Forcing Tides --- ADCIRC 9 harmonics
River discharge – USGS daily mean data
Surface Wind and Heat Flux (NAM/NARR)
Open BC non-tidal water level (NWLON)
Open BC T and S (WOA2001)
All forcing data compiled for
(14 yr time-series)
Operational forcing for nowcast and 3-day forecast
ADCIRC: Advanced Circulation Model
NAM: North American Mesoscale Model
NARR: North American Regional Reanalysis
NWLON: National Water Level Observation Network
WOA: World Ocean Atlas

6. NAM/NARR Wind and Surface Fluxes
Surface wind, air pressure, heat flux and long wave radiation
Surface temperature is NOT relaxed to observations

7. Effects of OBC Temp. and Salinity
Do not have results yet for WOA01 vs. WOA05 but have compared WOA01 to GODAS during model development
GODAS OBC TS gives less stratified system in lower bay compared to data
WOA OBC TS gives stratification of lower bay closer to measured data

8. Effects of C & D Canal flux
Inflow brings low salinity water into upper bay
Important to incorporate C & D canal in model for upper bay physical structure and dynamics
Gives better upper bay salinity structure prediction

9. Effects of Turbulence Closures
Compared the four closures:
1. Mellor-Yamada 2.5
2. KPP
3. Generic Length Scale (GLS) Mellor-Yamada
4. Generic Length Scale (GLS) K-omega
Results:
Mellor Yamada (MY) 2.5 similar to KPP
GLS K-omega similar to GLS MY 2.5
GLS K-omega gives best comparison to data in terms of vertical mixing/stratification

10. ChesROMS Available through SourceForge

11. Retrospective Run (1991 - 2005) (chief architect, Dr. Jiangtao Xu)
15 year retrospective
validation run
Large variations in
freshwater discharge
Lets focus on 2003 as
an example

12. Temperature and salinity (2003)
CB5.3
Mid Bay
Temperature
simulation
excellent
Salinity
not as good

13. 2003 Model Skill for Temperature
Correlations on the
order of 0.99
Normalized
standard deviation
close to 1

14. 2003 Model Skill for Salinity
Correlations on the
order of
Normalized
standard deviation
generally > 1
The model tends to
underestimate the salinity
variabiliy in most regions,
though there are some
exceptions, like in some
of the flank (shallow
stations)

15. Why the Reduced Skill for Salinity?
At least partially due to
smoothed topography
It has also been suggested
that ROMS tends
underestimate stratification
(is this true?)
The fact that the model tends
to underestimate the
standard deviation is
consistent with over mixing

16. Thank You

17. ChesROMS Biogeochemical Model - Work in Progress
(chief architect Dr. Jerry Wiggert)
Based on Fennel et al. core
model bundled with ROMS
NPZD type model with oxic
sediment denitrification
Adding DON
ISS loading
Atmospheric N deposition
Anoxic benthic denitrification
Water column denitrification,