1. Jie Liu EOSC 571 Term2 Evaluation of NEMO model on Fraser
River plume in the Strait of Georgia
2. Contents 1. Motivation 2. Main task 3. Research Questions 4.
Methods 5. Research plan
3. Motivation Strait of Georgia and Salish Sea are home to a
large population of residence in BC. Many activities in the Fraser
River estuary are affected by salinity intrusions. Motions of
Fraser River plumes influence pollutant dispersal, sedimentation
and nutrient. On-going need to assess the impact in coastal
communities(NASA)
4. Main task N (Soontiens et al, 2015) NEMO Model in regional
configuration 398 * 898 * 40 gird cells 150 rivers parameterized
Produce nowcasts and forecasts
5. Main task
(http://nbviewer.ipython.org/urls/bitbucket.org/salishsea/analysis/ra
w/tip/Idalia/Drifters_Ariane_Comparison.ipynb) Drifters: Released
near the Fraser mouth last September
6. Research Questions Aim: Test and evaluate river treatments
for Fraser River as well as other external forcing factors, such as
tide and wind, to acquire more accurate plume properties in nowcast
and forecast model results and better simulate surface currents in
the Fraser River plume. 2 In which way should I add river treatment
into the NEMO model domain and what physical factors should be
taken into account? How do river discharge, tide and wind affect
plume properties, such as salinity? How do plume properties vary
spatially and in short and long time scales? What model skill
should I use to evaluate Fraser River plume from NEMO model results
in Salish Sea domain?
7. Methods River treatment in the model Prolong the length,
broaden the width and deepen the depth of river channel in model
domain. Straight or curved river channel? Up to where? Mission,
Hope or somewhere else? Perform hindcast for last September
Boundary conditions: 1) no tidal energy gets to the eastern edge of
river channel. 2) steady-state river discharge at points outside
the tidal influence.(Google map) Sensitivity experiments of
lengths
8. Methods River discharge at river mouth Currently: using data
from Environment Canada gauge at Hope. Alard & Anne s estimate
of discharge at Chilliwack: Q = Marks estimate of discharge at
Fraser River mouth = My estimate of discharge at Fraser River
mouth: Q = QQQ ChehalisHarrisonH ba +++ ope 500012.1 +QHope Does
not experience tidal fluctuations Not accurate enough to estimate
discharge at river mouth QQQ PittHarrisonH ++ ope QPortMann
9. Methods Assessment of river discharge and tide in the
estuary and near-field plume area Stratification and position of
salt wedge R.A.Kostaschuk & L.A.Atwood develop a multiple
regression model to predict Fraser River salt wedge position.
M.J.Halverson & R.Pawlowicz derive a conceptual model for the
combined effect on the Fraser River plume salinity. P.MacCready
estimates the importance of tide induced mixing with tidally
averaged, volume integrated mechanism energy budget in ROMS.
Hindcast is needed to perform: a) Select several stations, such as
New Westminster, Mission and Hope b) Simulation with all the
forcing conditions, including tides and atmospheric forcing. c)
Simulation with all the forcing except tide. d) Simulation with all
the forcing but only tuning several constitutes of tide.
https://www.google.com/search?newwindo
10. Methods Assessment of wind in the far-field plume area
Perform hincasts from period last year or this year: a) Simulation
with strong local wind and flood tide b) Simulation with weak local
wind and flood tide c) Simulation with strong local wind and ebb
tide d) Simulation with weak local wind and ebb tide. May need
sensitivity experiment on Turbulence Closures a) Generic Length
Scale(GLS[Madec et al, 2012]) calculate vertical mixing and
turbulence b) Large-McWilliams-Doney(LMD[Large et al, 1994]) been
added in
11. Methods Surface salinity comparisons with ferry
observations 3 Data: Daily surface salinity from Queen of Alberni,
VENUS(ONC). Four round trip per day. Complete transect takes about
2hr.
12. Methods Surface salinity comparisons with ferry
observations Analysis: a)Comparisons of daily surface salinity
plots allow to see the features of variation and difference between
observation. b) Comparisons in different time period since last
September is feasible to excavate short and long time scales of
plume salinity variation.
13. Methods Evaluation of model skills Skill Score(SS) for
sensitivity experiment in estuary, near- and far-field plume: SS =
1-MSE/MSER Where MSE = < > SS > 0 improvement SS < 0
worse SS = 1 perfect ( )om 2 Willmott Skill(Willmott[1981]) for
model skill(different physical variables) ( )ooo MSE WS + = m 2
1
14. Solutions wrap-up In which way should I add river treatment
into the NEMO model domain and what physical factors should be
taken into account? River treatment in the model How do river
discharge, tide and wind affect plume properties, such as salinity?
Assessment of river discharge, tide and wind in the whole
estuary-plume system How do plume properties vary spatially and in
short and long time scales? Salinity comparisons with ferry
observations and CTD observations What model skill should I use to
evaluate Fraser River plume from NEMO model results in Salish Sea
domain? Evaluation of model skill
15. Research plan Start: Compare surface salinity with
observations(last Sep up to now and future) Compare surface
currents with drifters(last Sep, Oct) Add river treatment into
model Sensitivity test of paramaters SS Simulation with all the
forcing Simulation with all the forcing except tide Simulation with
all the forcing with only several tidal constituents Simulation
with strong wind, flood tide Simulation with strong wind, ebb tide
Simulation with weak wind, strong tide Simulation with weak wind,
ebb tide WS Improve nowcast and forecats Perform hincast
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