Download presentation
Presentation is loading. Please wait.
Published byMaleah Huddle Modified over 9 years ago
1
Jerome Fiechter, Andy Moore, Gregoire Broquet Ocean Sciences Department University of California, Santa Cruz ROMS Workshop, Sydney, April 2009 Improving Ecosystem Model Predictions through Data Assimilation
2
Outline Physical/biological properties of Coastal Gulf of Alaska (CGOA) Physical/biological properties of Coastal Gulf of Alaska (CGOA) Ocean circulation, ecosystem, and iron limitation models Simulation results for 1998-2002 without data assimilation Simulation results for 2001 with data assimilation
3
CGOA Physical and Biological Properties Physical Variability Downwelling-favorable wind regime (Stabeno et al., 2004) AS intrinsic mesoscale variability (Combes and Di Lorenzo, 2007) Anticyclonic (Yakutat) eddy passages (Okkonen et al., 2003) Biological Variability CGOA: high-productivity shelf, fisheries Subarctic Gyre: HNLC region (Lam et al., 2006) Iron limitation on primary production (Strom et al., 2006) Interannual Variability 1997-1998 El Niño; 1999 La Niña 1999 NEP “Cold” Regime Shift (Peterson and Schwing, 2003) 2002 NEP Subsurface Cold Event (Curchitser et al., 2005)
4
Coastal Gulf of Alaska Ocean Circulation Model ROMS: ~10 km horizontal resolution, 42 vertical levels One-way offline nesting with North East Pacific ROMS Monthly mean atmospheric and open boundary forcing Macro Nutrients from monthly WOA01 climatology Dissolved iron from VERTEX (Martin et al., 1989)
5
Lower Trophic Level Ecosystem Models NPZD+Fe (Powell et al., 2006; Fiechter et al., 2009) NPZD+Fe (Powell et al., 2006; Fiechter et al., 2009) NEMURO+Fe (Kishi et al., 2007; Fiechter and Moore, 2009) (from Kishi et al., 2007) Strom et al., 2007 NPZD PS: Nano P PL: Diatoms ZS: Ciliates ZL: Copepods ZP: Krill Fe
6
RESULTS: PART I INTERANNUAL VARIABILITY (1998-2002) ROMS + NEMURO/NPZD + Fe-limitation WITHOUT DATA ASSIMILATION
7
Surface Chlorophyll EOFs: Models vs. Observations NEMURO+FeNPZD+FeSeaWiFS
8
NEMURO/NPZD Surface Chlorophyll, 1998-2002 Taylor diagrams with respect to SeaWiFS based on monthly means ( NEMURO+Fe, NPZD+Fe ) 2001 LACK OF VARIABILITY
9
Sea Surface Height: GAK Line, 1995-2004 ROMS AVISO GAK Line GAK Stations ROMS vs. AVISO
10
RESULTS: PART II SEASONAL VARIABILITY (2001) ROMS + NPZD + Fe-limitation WITH DATA ASSIMILATION
11
IS4DVAR Data Assimilation CASE NAME 7-DAY SSH (AVISO) 5-DAY SST (Pathfinder) IN SITU T/S (GLOBEC) 8-DAY CHL (SeaWiFS) FREENO SSHTYES NO SSHTP (AD, PASS)YES SSP (AD, PASS)NO YES Configuration: ROMS+NPZD+Fe, adjoint/passive biology Assimilation: 7-day cycle, 1 outer (NL) loop, 10 inner (TL/AD) loops Strong constraint (no model error), adjust IC only, model space search Univariate background error covariance: a) isotropic, homogeneous correlations (50km horiz., 30m vert.) b) std deviations based on 10-year non-assimilated solution Observation std deviations: SSH=2cm; T=0.25C; S=0.1; Chl=0.5mg/m 3
12
Sea Surface Height, 2001 RMS errors and correlations with AVISO based on weekly means FREE SSHTSSHTP-BIOADSSP-BIOAD
13
Sea Surface Temperature, 2001 RMS errors and correlations with Pathfinder based on weekly means FREESSHTSSHTP-BIOAD SSP-BIOAD
14
Sea Surface Height, 2001 Taylor diagrams with respect to AVISO based on weekly means
15
NPZD Surface Chlorophyll, 2001 RMS errors and correlations with SeaWiFS based on monthly means FREESSHTSSHTP-BIOADSSHTP-BIOPASS
16
NPZD Surface Chlorophyll, 2001 RMS errors and correlations with SeaWiFS based on monthly means SSHT-BIOADSSHT-BIOPASSSSP-BIOADSSP-BIOPASS
17
NPZD Surface Chlorophyll, 2001 Taylor diagrams with respect to SeaWiFS based on monthly means NO BIO ASSIM PASSIVE BIO ASSIM ADJOINT BIO ASSIM
18
NPZD Surface Chlorophyll: Seasonal Means, 2001 FREESSHTSSHTP-BIOADSeaWiFS APR-JUN JUN-AUG AUG-OCT
19
Surface Chlorophyll and Nutrients: GAK Stations, 2001 Comparisons between model, SeaWiFS, and in situ chlorophyll
20
RESULTS: PART III SEASONAL VARIABILITY (2001) ROMS + NEMURO + Fe-limitation WITH DATA ASSIMILATION
21
NEMURO Surface Chlorophyll, 2001 RMS errors and correlations with SeaWiFS based on monthly means FREESSHTSSHTP-BIOPASSSSP-BIOPASS
22
NEMURO Surface Chlorophyll: Seasonal Means, 2001 FREESSHTSSHTP-BIOPASSSeaWiFS APR-JUN JUN-AUG AUG-OCT
23
Summary Interannual variability, no data assimilation, 1998-2002 Models reproduce spring bloom, underestimate fall bloom Models good on “normal” years, not so good on “abnormal” years Seasonal variability, data assimilation, 2001 Chlorophyll not improved by assimilation of physical data only Chlorophyll improved by assimilation of biological data Chlorophyll assimilation improved by using adjoint biology Assimilation incompatibilities between physics and biology Future work Adjoint vs. passive NPZD solutions (sensitivity studies) Assimilation with NEMURO (Chl to small/large phytoplankton) Forecast skill assessment for physics and biology
24
Collaborators: H. Arango (Rutgers), K. Bruland (UC Santa Cruz), E. Curchitser (Rutgers), E. Di Lorenzo (Georgia Tech), C. Edwards (UC Santa Cruz), K. Hedstrom (ARSRC), A.Hermann (NOAA/PMEL), B. Powell (U. Hawaii),Hermann (NOAA/PMEL), B. Powell (U. Hawaii), T. Powell (UC Berkeley) Funding: National Science Foundation (U.S. GLOBEC)
25
Iron Limitation on Phytoplankton Growth Nitrate-limited phytop. growth rate: Dissolved (available) Iron: Phytop.-associated Iron: Iron uptake:Optimal Fe:C: Realized Fe:C: Iron-limited phytop. growth:
26
Chlorophyll Vertical Profiles: GAK Stations, 2001
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.