Update on the Ecological Model:
Box Model Version
Mark Brush (VIMS)CHRP October 8, 2009
Officer Box Model
Current Activities
• Expanding from 2001 – 2008
• Improved salinity functions around the bay: NuShuttle data
Alternate S functions:- Cosine functions- Insomniacs + NuShuttle- Supplement with buoy data when available
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J F M A M J J A S O N D
Cosine functionInsomniacs / NuShuttleBullocks Reach buoy
Relating Model Daily Average Results to Management Criteria
Mark Brush (VIMS)CHRP October 8, 2009
One potential problem re: management use of the model:
• RI O2 criteria focus on instantaneous values
• Our eco model simulates daily mean O2
• Models can simulate diel O2 variations, but …
Rhode Island DO criteria:
Surface Waters (and waters without a pycnocline):
“Waters with a DO concentration above an instantaneous value of 4.8 mg/l shall be considered protective of Aquatic Life Uses.”
Bottom Waters (waters with a pycnocline):
As above, plus …
“When instantaneous DO values fall below 4.8 mg/l, the waters shall not be:
1. Less than 2.9 mg/l for more than 24 consecutive hours during the recruitment season; nor
2. Less than 1.4 mg/l for more than 1 hour more than twice during the recruitment season; nor
3. Shall they exceed the cumulative DO exposure presented in Table 3.A.”
Concept for GEMBox / GEM-OBM:
• daily mean DO• instantaneous minimum DO • time with DO below 2.9 mg/l• time with DO below 1.4 mg/l
Use buoy O2 data to look for relationships between:
DO mean
DO NCP CR?
2.9DO
Inst. min
2.91.4
t2.9
t1.4
Test sites:
• North Prudence• Conimicut Point• Bullocks Reach• Greenwich Bay
2003, 2005-07
y = 0.6496x + 1.1152R² = 0.7014
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.005x - 0.9433R² = 0.9399
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• North Prudence
2003 SURFACE
BOTTOM
Test sites:
• Conimicut Point
2003 SURFACE
BOTTOM
y = 0.6281x + 0.6985R² = 0.6692
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.0939x - 1.2177R² = 0.9206
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• Bullocks Reach
2003 SURFACE
BOTTOM
y = 0.6679x + 1.2682R² = 0.4423
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.0719x - 1.1773R² = 0.9379
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• Greenwich Bay
2003 SURFACE
BOTTOM
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Need a change-point regression?
All years together …
2003, 2005-07
y = 0.7406x + 0.7954R² = 0.706
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 0.9813x - 0.9535R² = 0.9032
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• North Prudence
2003, 2005-07 SURFACE
BOTTOM
Test sites:
• Conimicut Point
2003, 2005-07 SURFACE
BOTTOM
y = 0.7325x + 0.2965R² = 0.7139
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 0.9784x - 0.7465R² = 0.909
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• Bullocks Reach
2003, 2005-07 SURFACE
BOTTOM
y = 0.8193x - 0.2138R² = 0.6508
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.057x - 1.1834R² = 0.9093
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Test sites:
• Greenwich Bay
2003, 2005-07 SURFACE
BOTTOM
y = 1.1415x - 2.6697R² = 0.8635
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.0947x - 2.239R² = 0.8783
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
All sites & years together …
Test sites:
• All Sites
2003, 2005-07 SURFACE
BOTTOM
y = 0.9352x - 1.093R² = 0.7565
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MinO2surf, mg/l
TIMEsurf<2.9 mg/l
TIMEsurf<1.4 mg/l
y = 1.0215x - 1.2893R² = 0.8609
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MinO2bott, mg/l
TIMEbott<2.9 mg/l
TIMEbott<1.4 mg/l
Predicting DO Criteria Attainment:
• Inst. min. DO and time below DO thresholds appears predictable directly from daily mean DO
• Addition of terms for metabolism does not appear to help
• Fit is especially good in bottom waters, which is good news
• Relationship appears robust across years, and to a lesser degree across sites
• PROPOSAL: fit statistical distribution functions by site (years aggregated) with all available buoys to predict criteria attainment/violation from modeled daily mean DO