MODELING 2010 IN MASSACHUSETTS BAY USING THE UNSTRUCTURED-GRID BAY EUTROPHICATION MODEL

Transcription

1 MODELING 2010 IN MASSACHUSETTS BAY USING THE UNSTRUCTURED-GRID BAY EUTROPHICATION MODEL C. Chen, L. Z. Zhao, R. C. Tian and P. F. Xue MITSG Sea Grant College Program Massachusetts Institute of Technology Cambridge, Massachusetts NOAA Grant No. NA10OAR Project No R/RC-116

2 Modeling 2010 in Massachuse2s Bay using the unstructured grid Bay Eutrophica9on Model Chen C.S., Zhao L.Z., Tian R.C. and Xue P.F. School for Marine Science and Technology University of Massachuse7s Dartmouth

3 OUTLINE - ObjecHves and Required Tasks - Physical simulahon (FVCOM) - Water Quality simulahon (UG- RCA) - MWRA ouvall projechon

4 1. Simulation of current, temperature and salinity for the calendar year 2010 using FVCOM 2. Simulation of water quality variables for the calendar year 2010 using UG- RCA, including inorganic nutrients, phytoplankton, chlorophyll and organic substances. 3. Assessment of dispersal of the MWRA outfall effluent, both in the horizontal and vertical. 4. Projection analysis on the possible influence of the MWRA outfall on water quality and ecosystem function in MB. Contract Tasks

5 Nested Regional and MB FVCOM System Regional FVCOM domain: up to 2.5 km Driven by five tidal constituents at GOM open boundary (M 2, S 2, N 2, K 1 and O 1 ); 33 rivers; WRF-assimilated meteorological forcing (wind, net heat flux/solar irradiance, and precipitation minus evaporation). - Data assimilation of all available T, S data MB FVCOM domain: km Driven by Regional FVCOM fields at the nested boundary and the same meteorological and river discharges (13 rivers). Total vertical layers: 30.

6 UG-RCA Simulation UG-RCA Driven by hourly FVCOM physical fields WRF-calculated solar radiation for photosynthesis winds for DO reareation point source loadings non-point source loadings rive discharges (3 rivers) atmospheric loading boundary conditions extrapolated based bio-monthly MWRA observations

7 Far-field stations Near-field stations MWRA field observation stations 25 stations (bio-monthly) plus 8 AF stations 8 Stations (monthly)

8 At In MB Monthly averaged wind Surface net flux River discharges

9 April 2010 Averaged Temperature Difference between April 2010 and 2009 Averaged Temperatures

10 April 2010 averaged salinity Difference between April 2010 and 2009 averaged salinities

11 April 2010 Averaged Currents Difference between April 2010 and 2009 Averaged Currents

12 September 2010 Averaged Currents Difference between September 2010 and 2009 Averaged Currents

13 Comparison between computed and observed surface temperature and salinity February June

14 Model- predicted surface temperature and salinity Temperature Salinity

15 Did the 2010 nutrient condition significantly differ from previous years? If yes for question 1, could the water quality condition significantly differ from previous years? Water Quality Simulation Question 1: Answer: Yes. Question 2:

16 F26 F27 ObservaHon of DIN in the bo7om- layer at stahons F26 and F27 Near the northern open boundary

17 Boundary condihon of NO3 (µm) (OA mapping results based on MWRA observahons) Jan. 30, 2010 Jan. 30, 2009

18 Boundary condihon of NO3 (µm) (OA mapping results based on MWRA observahons) Mar. 1, 2010 Mar. 1, 2009

19 Normalized root mean square error (NRMSE), 2010 versus 2009 Surface Bottom Chlorophyll NO3 DO

20 Simulated surface (black) and bo7om (red) DO Near- field stahons (except F22) Far- field stahons

21 Simulated surface (black) and bo7om (red) DIN Near- field stahons (except F22) Far- field stahons

22 Simulated surface (black) and bo7om (red) chlorophyll Near- field stahons (except F22) Far- field stahons

23 Chlorophyll comparison (Red: 2010 boundary; Black: 2009 boundary) Surface Bo7om

24 MulH- year comparison of DO in the bo7om layer Black: Blue: Red: StaHons: OuVall, N18, N07, F15, F13, F10)

25 MulH- year comparison of DIN in the surface layer Black: Blue: Red: StaHons: OuVall, N18, N07, F15, F13, F10)

26 MulH- year comparison of chlorophyll in the surface layer Black: Blue: Red: StaHons: OuVall, N18, N07, F15, F13, F10)

27 -The projection was done by the comparison between two runs with and without the MWRA outfall loadings under the same forcing conditions; - The outfall effluent plume is exemplified by using NH4, which is one of the most abundant effluent of inorganic nutrients. - Effluent horizontal dispersal and vertical scale are evaluated by the difference of NH4 concentration between the two runs. MWRA outfall projection - Comparison was made for DO, DIN and chlorophyll levels;

28 DIN projechon (black: with ouvall; red: without ouvall) Surface waters Bo7om layer

29 Do and chlorophyll projechon (black: with ouvall; red: without ouvall) Bo7om DO Surface chlorophyll

30 2010 OuVall plume at the last day of every two months (NH4 difference in µm) July Sept Nov

31 2010 ouvall plume verhcal scale at the last day of every two months (NH4 difference in µm) Jan Feb Mar July Sept Nov

32 The 2010 water quality condition (DO) remains similar to previous years The nutrient concentrations in January 2010 were significantly lower than previous year. Driven UG-RCA with such a condition, the model failed to capture the spring chl-a concentration peak. Model-simulated Chl-a concentration is very sensitive to the nutrient flux condition on the northern boundary area. The impact of MWRA outfall remains similar to previous years. Modification of RCA should be made to improve the Chl-a simulation. We have examined the previous model results back to 1995 to 2009, and the model generally fails to capture the peaks of spring and fall blooms. Conclusions Recommendations