Hybrid Variational-Ensemble Data Assimilation - Weather-Chaos
A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems
description
Transcript of A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems
![Page 1: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/1.jpg)
1
A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems
Zhijin Li and Yi ChaoJet Propulsion Laboratory
Jim McWilliams and Kayo Ide
UCLA
ROMS User Workshop, October 2, 2007, Los Angeles
![Page 2: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/2.jpg)
2
Integrated Ocean Observing System (IOOS):Modeling, data assimilation, forecasting and adaptive sampling
Theoretical Understanding &
NumericalModels
Products
Users:Managers
Education & Outreach
Observations(satellite, in situ)
Feedback & Adaptive Sampling
Information
Data Assimilation
Observing System Design
![Page 3: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/3.jpg)
3
Outline
1. Real-time Regional Ocean Modeling System (ROMS)
2. Three-dimensional variational data assimilation
3. Assimilated observations
4. Evaluation of analyses and forecasts
5. Observing system experiments (OSE)
6. Relocatability
![Page 4: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/4.jpg)
4
Coupled with Tides
Sea Surface M2 Tidal Currents
ROMS Simulation HF Radar Obs
RMS Error of SSHs
Tide Gauge
![Page 5: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/5.jpg)
5
Regional Ocean Modeling System
(ROMS): From Global to Regional/Coastal
12-km
Multi-scale (or “nested”) ROMS modeling
approach is developed in order to simulate the 3D ocean at the spatial scale (e.g., 1.5-km) measured by in situ and remote
sensors
1.5-km5-km15-kmModeling Approach
![Page 6: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/6.jpg)
6
Data Assimilation
Analysis
Forecast
Processing
Observations
When the numerical model is so good as its predictionis superior to the climatological (almanac) forecast
Model
Data Assimilation
![Page 7: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/7.jpg)
7
ROMS Analysis and Forecast Cycle:Incremental 3DVAR
Aug.100Z
Time
Aug.118Z
Aug.112Z
Aug.106Z
Initialcondition
6-hour forecast
Aug.200Z
xa
xf
3-day forecast
y: observationx: model
6-hour assimilation cycle
)()(2
1)()(
2
1min 11 yHxRyHxxxBxxJ TfTf
x
xxx fa
![Page 8: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/8.jpg)
8
Why a There-Dimensional Variational Data Assimilation
• Real-time capability• Implementation with sophisticated and high
resolution model configurations• Flexibility to assimilate various observation
simultaneously• Development for more advanced scheme
![Page 9: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/9.jpg)
9
3DVAR: Weak Geostrophic Constraint and Hydrostatic Balance
TSfTS
aaTSfuv
aTSf
TS
uv
xx
xxx
xxx
x
x
x
S
T
v
u
x
aaTSuv xxx TS
Guv xx
aTS xxx
TSS xx
Geostrophic balance
Vertical integral of the hydrostatic equation
ax ageostrophic streamfunction and velocity potential
![Page 10: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/10.jpg)
10
Inhomogeneous and anisotropic 3D Global Error Covariance
Cross-shore and vertical section salinity correlation
SSH correlations
Kronecker Product
![Page 11: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/11.jpg)
11
Assimilated observations:Satellite infrared SSTs
NOAA GOES
NOAA AVHRR
Infrared, High resolutionCloud contamination
Microwave, Low resolution (25km)No cloud contamination
NASA AquaAMSR-E
NASA TRIMMTMI
![Page 12: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/12.jpg)
12
Assimilated observations:Satellite SSHs along track
JASON-1
Resolution: 120km cross track, 6km along track
![Page 13: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/13.jpg)
13
Integrated Ocean Observing Systems
0
100
200
300
400
500
600
700
800
900
213
215
217
219
221
223
225
227
229
231
233
235
237
239
241
243
245
Year Day
Nu
mb
er o
f C
asts
/Day
<55
<110
<220
<440
<1100
T/S profiles from gliders Ship CTD profiles Aircraft SSTs AUV sections
![Page 14: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/14.jpg)
14
Assimilated Current Observations
Acoustic Doppler Current Profiler (ADCP)
BottomShipboard Buoy
High Frequency Radar Mapped 2D surface current
![Page 15: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/15.jpg)
15
3DVAR with First Guess at Appropriate Time (FGAT)
fttt
tt
ttt
tftt
Ttt
ttt
tfttt
Tt
xxx
yHxxHRyHxxHxBxJ
000
0
0
0
0
0
000
2
1
2
1
12
1
2
1
1
2
1
2
1
3.5DVar
If ,0 tt xx FDAT 3DVar is equivalent to 4DVar
![Page 16: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/16.jpg)
16
ROMS Performance Against Assimilated Data
August 2006 Mean
Temperature (C)
Salinity (PSU)
All Gliders Mean Diff RMS Diff
-0.3 0.3 0.0 0.75
-0.1 0.1 0.0 0.20
![Page 17: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/17.jpg)
17
Comparison of Glider-Derived Currents (vertically integrated current)
AOSN-II, August 2003 Black: SIO glider; Red: ROMS
![Page 18: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/18.jpg)
18
Forecast CorrelationPredictability during AOSN-II
Note: because gliders are moving, one cannot estimate the persistence
RMSE
![Page 19: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/19.jpg)
19
Observing System Experiment (OSE)
– Typically aimed at assessing the impact of a given existing data type on a system
– Using existing observational data and operational analyses, the candidate data are either added to withheld from the forecast system
– Assessing the impact
![Page 20: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/20.jpg)
20
Observing System Experiment (OSE):Glider Data Denial Experiment
Temperature Salinity
1st week 2nd week
CalPoly SIO WHOI
w/o CalPoly glider
with CalPoly glider
RMS Error
![Page 21: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/21.jpg)
21
HF radar
ROMS without HF radar data assimilation
ROMS with HF radar data assimilation
Impact of HF Radar
![Page 22: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/22.jpg)
22
Southern California Coastal Ocean Observing System (SCCOOS)
http://ourocean.jpl.nasa.gov/SCB
Southern California Bight
US WEST COAST
![Page 23: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/23.jpg)
23
Real-Time SCCOOS Data Assimilation and Forecasting System
http://ourocean.jpl.nasa.gov/SCB
![Page 24: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/24.jpg)
24
Evaluation with HF radar velocities
![Page 25: A Three-Dimensional Variational Data Assimilation in Support of Coastal Ocean Observing Systems](https://reader036.fdocuments.in/reader036/viewer/2022062410/5681545a550346895dc273ae/html5/thumbnails/25.jpg)
25
Toward a Relocatable ROMS Forecasting System:Demonstration for Prince William Sound, Alaska
9-km
1-km3-km