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Assimilating SST and Ocean Colour into ocean forecasting models
Rosa Barciela, NCOF, Met Office
www.ncof.gov.uk
Contents
• Introduction– Operational FOAM
– Biogeochemical modelling
• Satellite data assimilation in FOAM– Medspiration SST
– SeaWiFS Ocean Colour
– Future plans
• Operational Requirements - GlobCOLOUR
www.ncof.gov.uk
Forecasting the open ocean: the FOAM system
• Operational real-time deep-ocean forecasting system
• Daily analyses and forecasts out to 6 days
• Low resolution global to high resolution nested configurations
• Relocatable system deployable in a few weeks
• Hindcast capability (back to 1997)
• Assimilates T and S profiles, SST, SSH, sea-ice concentration
FOAM = Forecasting Ocean Assimilation Model
Real-time data
Obs QC
Analysis
Forecast to T+144
NWP 6 hourly fluxes
Automatic verification Product
delivery
Input boundary
data
Output boundary
data
www.ncof.gov.uk
Operational configurations
12km (1/9º) Mediterranean
6km (1/20º) North East Atlantic
36km (1/3º) North Atlantic and Arctic
12km (1/9º) North Atlantic1º Global
36km (1/3º) Indian Ocean
12km (1/9º) Arabian Sea
27km (1/4º) Antarctic
• All configurations run daily in the operational suite
www.ncof.gov.uk
Hadley Centre Ocean Carbon Cycle Model (HadOCC)
Model description
- Variable C:Chl ratio
- Coupled to carbon and alkalinity
- Normally used for climate studies
- Transported around the ocean by physical processes
- ‘NPZD’ ecosystem model
Aims
- Air-sea fluxes of CO2 using high-resolution GCM (1º go, 1/3º & 1/9º NA)
- Assimilation of Ocean Colour & EO data to improve these fluxes
- 10 year hindcast (1997-2006) with/without data assimilation
www.ncof.gov.uk
Contents
• Introduction– Operational FOAM
– Biogeochemical modelling
• Satellite data assimilation in FOAM– Medspiration SST
– SeaWiFS Ocean Colour
– Future plans
• Operational Requirements - GlobCOLOUR
Operational FOAM assimilation of GHRSST-PP products
Assimilation of Medspiration data
– FOAM adapted to use GHRSST obs
– 3-month hindcast run with/without assimilation of Medspiration data
– Main differences in Gulf stream region
– Assimilation of Medspiration obs improve the ocean temperature analysis by 0.1K RMS.
– Improvement not only at the surface but over the top 600 m
0
200
400
600
800
1000
0.7 0.8 0.9 1 1.1 1.2 1.3RMS Difference (K)
Dep
th (
m)
1/9° GHRSST1/9° control
www.ncof.gov.uk
Future Plans
To use GHRSST-PP data operationally from next year(development work required)
www.ncof.gov.uk
Contents
• Introduction– Operational FOAM
– Biogeochemical modelling
• Satellite data assimilation in FOAM– Medspiration SST
– SeaWiFS Ocean Colour
– Future plans
• Operational Requirements - GlobCOLOUR
www.ncof.gov.uk
Phytoplankton background error before the first analysis.
Phytoplanktonanalysis error after the first analysis, with data everywhere.
Phytoplankton errors (mmolN/m3)
Assimilation of Derived ChlorophyllR
esu
lts fr
om 3
-D tw
in
exp
erim
ent
s
www.ncof.gov.uk
Assimilation of Derived Chlorophyll
Total Dissolved Inorganic Carbon (mmolC/m3)
Control - truth
Assimilation - truth
Daily Mean RMS Errors in the North Atlantic from 3-D Twin Experiments
- Air-sea exchange of CO2
significantly improved after assimilating ocean colour data
- Joint assimilation of Medspiration SST and ocean colour is desirable as carbon solubility is strongly dependent on temperature
- 10 year hindcast will benefit from using a long-term SST, ocean colour dataset
www.ncof.gov.uk
• 10-day test run
Free Run Chlorophyll DA
RMS error = 0.46 RMS error = 0.27Mean error = -0.28 Mean error = -0.11
Aim: Improvement of pCO2 estimation by assimilating ocean colour
Assimilation of Derived Chlorophyll
www.ncof.gov.uk
Future plans
To transition the FOAM-HadOCC system into pre-operational state by 2008
(assimilation of ocean colour products)
www.ncof.gov.uk
Contents
• Introduction– Operational FOAM
– Biogeochemical modelling
• Satellite data assimilation in FOAM– Medspiration SST
– SeaWiFS Ocean Colour
– Future plans
• Operational Requirements - GlobCOLOUR
www.ncof.gov.uk
GlobCOLOUR/Ocean Colour Operational User Requirements
• Specific requirements for GlobCOLOUR
- L2 Global Area Coverage of chl a plus quantified errors from merged and individual sensors
- Best possible accuracy: essential to decrease errors in derived chl below 35%
- Extensive product quality control: include quantified errors and quality flags
- Validation against in situ data and across biogeochemical regions.
- Product format: WMO GRIB or netCDF
- Delivery method: FTP
- Large biases in the merged product corrected by in situ data
- Spatial resolution: 4 Km spacing (highest resolution models have)
- Bias information from individual sensors
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GlobCOLOUR/Ocean ColourOperational User Requirements
• Joint GlobCOLOUR/Medspiration products would be an advantage:- single file format- single file delivery - reduced data processing time- diagnostic data set applied to GlobCOLOUR data
For operational purposes …
• Long-term provision of quality-controlled products in a timely (within 1 day) manner.
- sustainability is key as lots of investment required to use the data- stable formats and delivery: (very) high availability and reliability
• NW European Shelf (NOOS) user requirements may need to be gathered ([email protected])
