Transcript Dias nummer 1

DMI forecasting system for
Baltic-North Sea (DMI BSHcmod),
and also for Greenland,
NW Shelf (Hycom)
Jens Murawski (DMI)
Agenda
• DMI BSHcmod: An operational
Baltic and North Sea model
–
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History
Model features
Quality
Ongoing developments
• An introduction to
– DMI drift model
– N. Atlantic/Greenland model – HYCOM
– Wave model - WAM
History of
BSH/DMIcmod
Organisation
of the DMI
• 2000: BSH kindly provided
its operational model
BSHcmod
1998: DMI operational
oceanography section
• 2000: BSHcmod run
operationally in DMI with
DMI forcing
2005: DMI Marine
Forecasting Centre
• 2003: Information system –
http://ocean.dmi.dk
2006: DMI Centre of
Ocean and Ice
• 2004: SST assimilation
(ODON)
• 2005: MERSEA Baltic V1
• 2006: MERSEA Baltic V2
2006: Marine Ecological
Modelling Centre
(Jointly by DMI-NERIDIFRES)
Current model features
Forcing
Meteo. Forcing - DMI-Hirlam
15km/5km, 60/54 hours prognoses
River runoff:
realtime data from
(SMHI, BSH) & adjusted
climatology for the rest
Open boundary:
T/S: dynamic boundary
from POLCOMS Monthly
climatology
Water level: Tides, surge,
baroclinically corrected
water level
Current DMI 3D ocean model: BSHcmod
• BSHcmod, provided by BSH
2000, developed by DMI
• 3 nested layers:
6-3-0.5nm
• Coupled ocean-ice
• two way nesting
• Flooding-drying
• 50 layers (8-2-2…-50)
• Twice daily,
54h forecast
• Daily river runoff +
climatology
NEA: 6 nm, NS/BS: 3 nm, IDW: 0.5 nm
DMI BSHcmod: new features
1.) Surface heat flux: Windspeed & Airtemp. dependent
2.) Including vertical Penetration of short wave
radiation
3.) Vertikal mixing: K-epsilon, k-omega model adapted
4.) Horizontal mixing: a new term to control div/conv.
5.) Surface momentum flux: currents dependent
6.) Simplified & Full ensemble Kalman filter for SST
assimilation
Surface heat flux (cont.): SST
Change heat flux coeffcient, Kara et al. (2000)
Bias
[Cº]
Comparisson with
ODON data for 2001
SST Bias improves ~ 0.1°C
CL= f (W,Ts–Ta)
Vertical mixing
Improving diffusivities of momentum, heat and
salt
• k-ε turbulence model
e.g. Axell, JGR (2002)
• stability functions in terms of shear and
gradients of S and T
Canuto et al., JPO: Part I (2001) + Part II (2002)
DMI cmod validation
k-ω based mixing scheme:
(preliminary)
salinity in Great Belt
Ref.
Days since 2000/07/15
k-ω
Bottom temperature:
FYN6700053
Old k-ω
New k-ω
spring
summer
autumn
winter
Wind friction
Wind induced shear
stress is current
velocity dependend
k-ω surface
boundary conditions
are z0 dependend
z0 is either const. or
sig. wave heigth dep.
Southern Baltic Sea
color: windspeed
arrows: currents (magnitude and direction)
color: currents (magnitude)
arrows: currents (direction)
New: currents dependend wind friction and wave height dependend
roughness length
Quality
Water level forecasts, peak error
DK stations, 2002-2004, 4 models
Cmod:
<10% in 2004
MIKE 21:
2D FD; official storm surge model; ~18% 2002-2004
MOG2D:
2D FE, from 2003
Staumod:
2D version of Cmod, no stations in IDW
Data assimilation, SST:
Larsen et al., JMS 2006
DA
model runs for 2001 by assimilating SST
from different products (NOAA 12, 14, 16)
Control
DA
Bias
0.78
0.07
RMSE
1.20
0.64
BSH/DMIcmod results
Surface currents
Salinity
kts
psu
Comparison of satelite SST with
simulated temperature values
Model-data comparison: Drogden Buoy
station, T/S at 3.6m (inflow signals)
Temperature, year 2004
Salinity, year 2004
Observation (red)
Model data (blue)
Bias(z) = -0.7 ,..., -0.3
Std(z) = 0.6 ,..., 1.1
Bias(z) = -0.03 ,..., 0.8
Std(z) = 2.0 ,..., 2.6
NOVANA
station
VSJ 20925
(southern
Kattegat)
Surface Temperature 1.0m
Bottom Temperature 36.6m
Bottom Salinity 36.6m
Surface Salinity 1.0m
North Atlantic/Greenland modelling
depth maps:
Etopo2
0.5deg-10km res.
22 layers
data assim.:
sst
2x/day, 66h
ECMWF 6hly forcing
Outline
1) Ocean modelling:
HYCOM setup for the Atlantic and Arctic Ocean (~50 km)
Nested around Greenland (~10 km)
2) Drift modelling for 2005:
Random walk diffusion
Normal distributed in time (40 days window),
1000 particles
2a) Drift as eggs:
On top of the Irminger Water component (use fixed
density), First feeding larvae after 300 degree-days
2b) Drift as pelagic larvae
Surface: 20m, 40m, 60m (use fixed depth)
Exponential temperature dependent increase in weight:
Wi~Wi-1*exp(T)
Settling when reaching 210 mg dry weight
Operational forecast for Greenland
•Currents
•Salinity
•Temperature
•Mixed layer deepness
•Ice thickness and concentration
SST monthly mean
SSS monthly mean
Profiles at Diskobay position
Drift model
Emergency module, used primarily for oil spill
Other apllications, floating object, dissolved substance, fish larvae
drift, …
Circulation model add-on module (HYCOM or BSHcmod)
The Fu Shan Hai collision, May 2003
The vessel sank at 68m depth,
and began to leak fuel oil
The oil rises as a plume from the
sunken ship
10 day simulation of Fu Shan Hai accident
depth maps:
Etopo5
sea ice:
NCEP
0.5deg-10km-2km
resolution
4x/day, 60h
Wave model
WAM Cycle4
Ongoing developments
Wave-current interaction
• DMI BSHcmod-WAM coupling
– Two-way interface ready
– WAM with current refraction running preoprational
– More coupling mechanisms to be added:
(Wave induced mixing)
Windspeed up to 20m/s
Wave-Current interaction,
01.10.2007 12:00
Differences of about ± 1m
around Greenland
Sign. wave height up to 7m
Δ(sign. wave height) = 1m,…,1.5m
SPM modelling
• GKSS SPM model is coupled with DMI BSHcmod
• Wave influenced vertical exchange of SPM
• Horizontal advection as passive tracer (Cmod)
Ecological modelling
• DMI BSHcmod-ERGOM coupling
– Framework ready, in model calibration
– Assimilating satellite chl-a
– Operationalisation
ERGOM
Sediment
concentration
regulates the
penetration depth
of light
Sediment dynamik influences
the nutrients concentration in
the water column.
Thank
you!!
HTTP://OCEAN.DMI.DK