Post on 21-Dec-2015
GODAE Final Symposium, 12 – 15 November 2008, Nice, France
Global High Resolution Analyses and Forecasts at the Mesoscale
H. Hurlburt1, Y. Drillet2, G. Brassington3, M. Benkiran4, E. Chassignet5, J. Cummings6, M. Drevillon7, H. Etienne4,
O. Le Galloudec2, E.J. Metzger1, P. Oke8, T. Pugh3, A. Schiller8, J.F. Shriver1, O.M. Smedstad9, B. Tranchant7,
A. Wallcraft1, G. Warren10
1Naval Research Laboratory, Stennis Space Center, MS, USA2Mercator-Océan, Ramonville Saint Agne, France
3Centre for Australian Weather and Climate Research, BoM, Melbourne, Australia4CLS, Ramonville Saint Agne, France
5Florida State University, COAPS, Tallahassee, FL, USA6Naval Research Laboratory, Monterey, CA, USA
7CERFACS, Toulouse, France8Center for Australian Weather and Climate Research, CSIRO, Hobart, Australia
9Planning Systems Inc., Stennis Space Center, MS, USA10Bureau of Meteorology, Melbourne, Australia
2004-2006 Sea Surface Height (SSH) Variability
From satellite altimetry
(CLS)
From a 1/12 Mercator Océan
simulation without data assimilation (using the
NEMO model)
(in m2)
SSH Variability in the Gulf Stream Region
45N
40N
35N
30N
45N
40N
35N
30N
80W 70W 60W 50W 40W
4 years from 1/12 global HYCOM
with climatological forcing and no
data assimilation
Along altimeter tracks in 4 orbits spanning 2000-
2007. From Hurlburt and
Hogan (2008, DAO) courtesy Gregg Jacobs (NRL).
MODIS Ocean Color vs 10-day Gulf Stream Region Current Speed Forecasts from 3
Mercator-Océan Systems on 23 April 2008
MODIS
1/12 global1/4 global
1/12 Atlantic
All the Mercator Océan systems use the NEMO model and SEEK data assimilation
East Australian Current System on 8 March 2007
1/10 Operational BLUElink Nowcast 1/10 BRAN 2.2 Reanalysis
± 2-day drifter trajectories overlaid on sea level anomalies and ocean currents
Both are global with 1/10 resolution in the Australian region (90E-180E, 75S-16N) and use MOM4 with multivariate EnOI data assimilation
GODAE Final Symposium, 12 – 15 November 2008, Nice, France
1/10 Operational BLUElink Nowcast 15 Feb 2007 – 30 Apr 2007
Eddies in Ocean Model Nowcasts vs SeaWiFS Ocean Color in the Northwestern Arabian Sea and
Gulf of Oman on 6 Oct. 2002
Adapted from Hurlburt et al. (2008; AGU Monograph 177)
Eddies in Ocean Model Nowcasts vs SeaWiFS Ocean Color in the Northwestern Arabian Sea and
Gulf of Oman on 6 Oct. 2002
Adapted from Hurlburt et al. (2008; AGU Monograph 177)
Prediction SystemResolution at 20N
1/16 NLOM8 km
1/32 NLOM4 km
1/8 NCOM18 km
1/12 HYCOM8km
1/32 NLOMn No Assim
% of Eddies Present in the Model
All eddies 70 90 55 80 35
Large eddies, 1-10 80 100 80 90 20
Small eddies, 11-20 60 80 30 70 50
Median Eddy Center Position Error, km
All eddies 35.5 29 48 50 42
Large eddies 42.5 37 57 68 38
Small eddies 32.5 22.5 47 44 42
Eddies in Ocean Model Nowcasts vs SeaWiFS Ocean Color in the Northwestern Arabian Sea and
Gulf of Oman on 6 Oct. 2002
Adapted from Hurlburt et al. (2008; AGU Monograph 177)
(in cm)
24°N
22°N
20°N
18°N
16°N
26°N
24°N
22°N
20°N
18°N
16°N
26°N
56°E 58°E 60°E 62°E 56°E 58°E 60°E 62°E 56°E 58°E 60°E 62°E
29 Sept 2002 6 Oct 200222 Sept 2002
1/32 NLOM Nowcast SSH and Currents with Altimeter Tracks Overlaid
Altimeter track data from ERS-2 (red), GFO (black), and JASON-1 (white) were assimilated daily using a 3-day data window and the model as a first guess Altimeter tracks are overlaid with the most recent seven days as solid lines Daily MODAS SST analyses are also assimilated Atmospheric wind and thermal forcing is from FNMOC/NOGAPS
Adapted from Hurlburt et al. (2008; AGU Monograph 177)
1/12 Global HYCOM forecasts vs. Verifying Analyses
20 Forecasts included in statistics* Reverts toward climatology at end of atmospheric forecast.
Atmospheric analysis forcing operational forcing* persistence
WorldOcean
Gulf Stream NW Arabian Sea and Gulf of Oman
EquatorialPacific
Kuroshio Yellow and Bohai
Seas north of
30N
1.0
0 10 20 30 10 20 30 10 20 30
Forecast length (days)
1.0
0.9
0.8
0.7
1.0
0.9
0.8
0.7
0.6
Med
ian
SS
H a
no
mal
y co
rrel
atio
n
Partly from Hurlburt et al. (2008; AGU Monograph 177)
Verification of 30-day Forecasts of SSH vs Unassimilated Tide Gauge Data
1/12 HYCOM, with analysis quality forcing
1/12 HYCOM, with operational forcing
1/32 NLOM 1/16 NLOM
Adapted from Hurlburt et al. (2008; AGU Monograph 177)
Open Ocean Islands Coastal Both
A 13-day moving average was applied to filter time scales not resolved by the altimeter data
0 .5 1.0C
Mercator Océan Atlantic SST Forecast Error vs SST Analysis
1-day RMS Error 7-day RMS Error
Length of Forecast (days)
RM
S E
rro
r (C
) persistence
forecast
Strong Coastal Upwelling Event off Southern Australia
Observed SST
Organisations
Bonney coast off South Australia is a location of frequent coastal upwelling
The upwelling in Feb 2008 was one of the largest events ever recorded
10 Feb 2008 BLUElink SST 10 Feb 2008
MODIS ocean color 30 Mar 08
Australia
15 Jan – 15 Feb mean winds
Organisations
• South Australia non tidal sea level exceeded 0.6m, 29 th October 2007
• Tasmania, Derwent River, non tidal signal ~0.4m, 9th August 2007
• Hobart Mercury, 10th August 2007 “WILD weather and huge downpours continue to flood three major valleys in Tasmania, triggering car crashes, fires and a dangerous landslide.”
Sea Level Anomaly
BLUElink Prediction of Coastal Trapped Wave Events around Australia
Organisations
Non
-tid
e re
sidu
al (
m)
South Australia, Thevenard coastal tide gauge
Comparison of OceanMAPs () and non tidal sea level CTG ()
BLUElink Coastal Trapped Wave Nowcast Accuracy at the Thevenard, Australia Coastal Tide Gauge
Thevenard
RM
SE
(m
)
Forecast period (days)
BLUElink Coastal Trapped Wave Forecast Accuracy around Australia