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Exploring the Potential of NCEP’s GODAS and CFS to Diagnose and Forecast Coastal Upwelling for California Current Ecosystem. Yan Xue, Boyin Huang Climate Prediction Center Janine Fisler University of Maryland at College Park. Acknowledgement: Wayne Higgins, Frank Schwing, Wanqui Wang, - PowerPoint PPT Presentation
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Exploring the Potential of NCEP’s GODAS and CFS to Diagnose and Forecast Coastal Upwelling for California Current Ecosystem
Yan Xue, Boyin HuangClimate Prediction Center
Janine Fisler
University of Maryland at College Park
Acknowledgement: Wayne Higgins, Frank Schwing, Wanqui Wang, David Behringer, Arun Kumar
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Rationale
Coastal upwelling brings nutrients from depth to the surface
Coastal ecosystems flourish in nutrient-rich waters
Monitoring and forecasting upwelling benefits ecosystem and fishery managers
www.oceanjsu.com
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Upwelling in California Current Ecosystem
Ekman Transport ~ along shore
wind stress
Pickett and Paduan, 2003
Huyer, 1983
Ekman Pumping~ wind stress curl
• North of 36˚N upwelling seasonally
• South of 36˚N upwelling year-round
• Onset of Upwelling season progresses from March to July along the coast
• Both onset date and intensity during upwelling season extremely important
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Upwelling Index (UI)(Southwest Fisheries Science Center)
Use NAVY’s FNMOC 3o x 3o and 1ox 1o Sea Level Pressure fields (6-hourly, monthly data since 1967)
Calculate geostrophic winds from SLP
Use along shore wind stress to calculate Ekman transport
SWFSC’s UI is the only routine upwelling product (500 references)
15 Standard Sites
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Global Ocean Data Assimilation System (GODAS)
Background: Assimilates temperature profiles, synthetic salinity,
altimetry into GFDL Modular Ocean Model v.3 Provides oceanic initial conditions for Climate Forecast
System (CFS) 75˚S to 65˚N with resolution of 1˚ by 1˚ 40 vertical levels, with 10m resolution in the upper 200m Pentad temporal resolution Forced by atmospheric Reanalysis 2 (R2) fields
Advantages: Ability to monitor ocean in near-real time (7 day lag) Can use marine fields instead of winds to approximate
upwelling, e.g. vertical velocity at 50-meter depth Coupled with CFS: potential for prediction
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SWFSC vs. GODAS UI: Climatology
Baja
60oN large disagreement South of 39oN large
disagreement
57oN – 39oN good agreement
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Compare both monthly and pentad upwelling
Climatology: 1982-2004 for both data sets
High correlation between 36oN - 57oN
Low correlation north of 57oN and south of 36oN
SWFSC vs. GODAS UI: Anomaly Correlation
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Which index is more accurate?
Few in situ observations to validate indices Difficult to make in situ observations
Problem:
Derive upwelling index using NCEP surface wind analyses (R1, R2, GDAS) similar to SWFSC index
Verify GODAS and SWFSC, NCEP wind-derived indices against with that derived from QuikScat winds,
Approach:
See Poster P1.3 “Multiple Coastal Upwelling Indices for the Western Coast of North America” by Boyin Huang, Yan Xue and Frank Schwing
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Cumulative Upwelling Index: CUI
Following Schwing et al., 2006
Calculate pentad date of climatological onset of upwelling season, “start date” (SD)
Calculate pentad date of maximum climatological upwelling, “maximum date” (MD)
Annually integrate upwelling index from SD to MD
Describe both total and anomalous upwelling
Schwing et al., 2006
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CUI 2005: Delayed Upwelling
48N
45N
39N
36N
33N42N
GODAS GODASSWFSC SWFSC
11(from David Foley, NOAA NESDIS)
2002
Strong Upwelling
2005
Weak Upwelling
SST
Phytoplankton
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CUI 2006: Healthy Upwelling
48N
45N
42N
39N
36N
33N
GODAS SWFSC GODAS SWFSC
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Standardized CUI Anomaly
• CUIA shifted from below- to above- normal in 1998 coincident with PDO shift
• Below-normal years: 88, 93, 97, 05
• Above-normal years: 99, 01, 02, 03, 06
• Poor agreement before 1985
• Below-normal years tend to have positive PDO and NINI3.4
88 9397 05
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Composites for Below-Normal YearsAMJ (1988, 1993, 1997, 2005)
• Positive PDO and warm NINO4 SST
• Anomalous low SLP in NP
• Cyclonic surface wind anom. consistent with SLP
• Upwelling dipole at 40N-45N
W at 50 m depth
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Dep
th
Temp at Depths W at Depths
• Warm SST anom. above 50-meter depth
• Upwelling reaches 300-meter depth at least
• 48N: Upwelling extends 3o offshore
• 42N-45N: Upwelling confined within 0.5o of the coast
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Target AMJ
0 Month Lead
April 1 I.C.
5 members
CFS Forecast
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Target AMJ
1 Month Lead
March 1 I.C.
5 members
CFS Forecast
1 month leadis not as skillful as 0 month lead
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Collaboration between NCEP and SWFSCthrough CTB Proposal
• Use high-resolution CFSRR winds and other NCEP reanalysis winds to improve the accuracy of estimations of coastal upwelling
• Determine skill of CFS to forecast variations in coastal upwelling
• Develop a biologically effective upwelling and transport index (BEUTI) using winds and upper-ocean density structure
• Determine model deficiencies and model requirements for coastal applications
• Real time monitoring and forecasting products of coastal upwelling
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Backup Slides
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0 Month Lead, AMJ
April 1 Initial Condition
5 members
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Critical Factors Controlling Primary Productivity and
Ecosystem Health Timing, intensity, and
duration of Upwelling Stratification of water
column Surface water temperature Turbulence Freshwater input/salinity Position of Jet Stream Light availability, etc. www.abc.net.au
Giant Kelp
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Annual Normalized CUI Anomaly: 1983 CUIA
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Annual Normalized CUI Anomaly: 1986 CUIA
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Annual Normalized CUI Anomaly: 1988 CUIA
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Annual Normalized CUI Anomaly: 1993 CUIA
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Annual Normalized CUI Anomaly: 1997 CUIA
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Annual Normalized CUI Anomaly: 2005 CUIA
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Annual Normalized CUI Anomaly: Disagreements
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