Transcript HYCOM ONR visit August 2002

A Hybrid Coordinate Ocean Model
(HYCOM) For Data-Assimilative
Ocean Modeling
RSMAS
August 19, 2002
• A multi-institutional effort on the development and
evaluation of a data-assimilative hybrid isopycnal-sigmapressure (generalized coordinate) ocean model (called
Hybrid Coordinate Ocean Model or HYCOM.)
• The partnering/collaborating organizations are the
University of Miami/RSMAS, the Naval Research
Laboratory, NOAA/AOML, the Los Alamos National
Laboratory, NERSC, LEGI, the Service Hydrographique et
Océanographique de la Marine (SHOM), NAVOCEANO,
Planning Systems Inc., Orbital Image Corp., and the
U.S.Coast Guard.
The primary computational goal is the
establishment of a global eddy-resolving real-time
ocean forecast system with sophisticated data
assimilation techniques that can be efficiently
executed on massively parallel computers
1. The ocean model: the HYbrid Coordinate
Ocean Model (HYCOM)
2. In-situ and satellite data
3. Data assimilation techniques
Background
- Rotating and stratified fluids => dominance of
lateral over vertical transport.
- Hence, it is traditional in ocean modeling to orient
the two horizontal coordinates orthogonal to the
local vertical direction as determined by gravity.
- The choice of the vertical coordinate system is the
single most important aspect of an ocean model's
design (DYNAMO, DAMÉE-NAB).
- The practical issues of representation and
parameterization are often directly linked to the
vertical coordinate choice (Griffies et al., 2000).
Currently, there are three main vertical coordinates
in use, none of which provides universal utility.
Hence, many developers have been motivated to
pursue research into hybrid approaches.
The hybrid coordinate is one that is isopycnal in
the open, stratified ocean, but smoothly reverts to
a terrain-following coordinate in shallow coastal
regions, and to pressure coordinate in the mixed
layer and/or unstratified seas.
The capability of assigning additional coordinate surfaces
to the oceanic mixed layer allows for sophisticated
closure scheme, such as the K-Profile Parameterization
(KPP).
Status of HYCOM Development
 HYCOM 2.0 (released 3 July 2001)
 Scalability via MPI and/or OpenMP (2-1000 cpus)
 Fortran 90 coding style
 Single source code, for all machine types
 Bit-for-bit multi-cpu reproducibility
 Nesting
 Off-line and one-way
 Based on enclosing region's archive files
 MICOM compatibility
 MICOM-like mode
 Can continue a true MICOM simulation
 Convert MICOM-like to HYCOM-mode
 Add layers near the surface
 Diagnostics
 Layer snapshots and animations
 Cross-section snapshots and animations
 Means and variabilities
 Transport sections
- Add halos for MPI to automatically support periodic
boundaries
- Support nested-domain open boundaries
- Fully global (Pan-Am grid)
- Alternative mixed layer models (G. Halliwell presentation)
Mellor-Yamada 2.5
Price-Weller-Pinkel
- Orthogonal curvilinear grids
- Single passive tracer
- NetCDF output files
To be released in September 2002
Other numerical developments (M. Iskandarani presentation)
HYCOM Long-term Goals for Operational Ocean Prediction
 .08 fully – global ocean prediction system transitioned to
NAVO in 2006
 ~7 km mid-latitude resolution
 Include shallow water, minimum depth 10-20 m
 Bi-polar (PanAm) grid for Arctic
 FY04-06 DoD HPC Challenge project essential
 Embedded ice model
 Increase to .04 resolution globally and transition to NAVO by
the end of the decade
 ~3.5 km mid-latitude resolution
 Good resolution for coastal model boundary conditions globally
 “Baseline” resolution for shelf regions globally
 Input to atmospheric and bio-chemical models
 John Kindle has NOPP funding for bio-chemical model
coupling to HYCOM
Coordinator:
Eric P. Chassignet ([email protected])
NORTH ATLANTIC BASIN-SCALE SIMULATIONS
Based on the CME, DYNAMO and MICOM experience
(1˚, 1/3˚ and 1/12˚, respectively)
- The CME comparison is completed (sigma-theta,
sigma2, and sigma2 + thermobaricity) [Chassignet
et al., to be submitted]
- 1/3˚ routine (interannual forcing – 40 years) [Hogan]
- 1/12˚ in progress (years 1999-2002 after spin-up)
[Hogan, Wallcraft, Chassignet, Hurlburt]
NORTH ATLANTIC REGIONAL SIMULATIONS
- Intra-American (Caribbean) Sea (standard configuration
for data assimilation testing) [Townsend, Wallcraft]
ECMWF forcing
Atlantic Model Configuration
• Horizontal grid: 1/12˚ (1678 x 1609 grid points, 6 km spacing on
average)
• 28°S to 70°N (including the Mediterranean Sea)
• 26 vertical coordinate surfaces (σ-theta reference)
• Bathymetry: Quality controlled ETOPO5
• Surface forcing: wind stress, wind speed, heat flux (using bulk
formula), E-P + relaxation to cllimatological surface salinity
• River runoff included
• Buffer zone: ~3° band along the northern and southern boundaries
with relaxation to monthly climatological T and S (Levitus)
10 x 16 Equal Ocean Decomposition
 Running on Brainerd (ARL)
 58,000 CPU hrs/model year on 160 CPUs
 770 GB/model year for daily 3-D output
 MPI parallelization
1/12° HYCOM ATLANTIC SIMULATION
~7 km resolution at mid-latitudes
Sea Surface Height
Sea Surface
Temperature
Forced by ECMWF 10 m reanalysis monthly climatological wind and thermal
fluxes, climatological surface salinity and relaxation to MODAS climatology
at the northern and southern boundaries (themohaline component)
18 degree Mode Water formation
18 degree Mode Water formation
1/12° Atlantic HYCOM
Deep Western Boundary Current
Denmark Straits Overflow Region
Observed transport
from current meters
5.2
10.7
13.3
Model transport
sum layers 20-26
ρ > 27.8 (NADW)
4.14
9.36
13.77
Dickson and Brown
1994 (JGR)
1/12° North Atlantic
HYCOM
layer 20 mean
speed
Denmark Straits Overflow
Cold fresh water
forms over shelf
in Nordic Seas
and spills over the
Denmark Strait
and entrains more
saline Labrador
Sea water
• No distinction is made between inflow and outflow boundaries
• The “well-posed” boundary conditions developed by Browning
and Kreiss (1982) are applied to the barotropic mode, i.e., the
barotropic pressure and velocities are advected into/out of the
domain via characteristics
• Relaxation to mass fluxes, interface depths, T, S, and density
is prescribed in a finite-width sponge zone
HYCOM
Nesting Applied to IAS
[Townsend,
Wallcraft]
North Atlantic, 0.32°
North Atlantic, 0.32°
SST
CI = 0.08° C
May 4
Intra-Americas Sea, 0.08°
SST
CI = 0.3° C
Jan 16
SST
CI = 0.08° C
May 4
Meridional Velocity, De Soto Canyon, Gulf of Mexico at 29.6N
0.32° North Atlantic HYCOM
Jul 14
0.08° Intra-Americas Sea HYCOM
Jul 14
Forced by 1979-1993 Monthly Mean ECMWF Reanalysis 10 m winds and
boundary conditions from the 0.32° North Atlantic HYCOM
0.32° North Atlantic HYCOM
Jan 16
0.08° Intra-Americas Sea HYCOM
Jan 16
Atlantic regional modeling
- Coastal seas around Florida Bay [Kourafalou]
• A nested approach is proposed for a high resolution
HYCOM application around south Florida
(large scale– regional scale– coastal scale)
• The regional model will provide boundary conditions for
limited area hydrodynamic, ecosystem and water quality
models in Florida Bay
• The simulations will be closely linked to ongoing
observational studies in Florida Bay and adjacent seas
The seas adjacent to Florida Bay:
Gulf of Mexico, West Florida Shelf and Florida Straits
(the shaded area marks the regional model domain)
Florida
elf
Sh
ida
lor
• Physical transport processes
impose strong hydrodynamic
links between Florida Bay and
the adjacent coastal seas.
F
st
We
50
0
30 N
Gulf of Mexico
Florida
Bay
00
20
25 N
• Significant transient inputs can
reach Florida Bay from remote
regions of the Gulf of Mexico.
50
20
00
0
100
Florida
Keys
Straits
Florida
Santaren
Channel
500
Cuba
Campeche Bank
Yucatan
Channel
Yucatan
Peninsula
20 N
90 W
20
00
85 W
80 W
Recent observational studies
provide evidence of transport
processes linking south
Florida coastal ecosystems
A comprehensive, multi-year, interdisciplinary data set is
available for model initialization, forcing and validation
Atlantic regional modeling
- SEED [Jacobs]
Slope To Shelf Energetics And Exchange Dynamics
To understand the mechanisms that
transfer properties (energy, mass,
momentum, heat, salt, …) across the
shelf slope
Focus Area
Gulf of Mexico,
Mississippi Bight,
west of the
DeSoto Canyon
Atlantic regional modeling
- DIADEM/TOPAZ [Evensen]
Implement and validate a model
system for hindcast simulations in
the Faroe-Shetland channel
Run the system in a multiyear
hindcast simulation to produce
current statistics which can be
used to derive design criteria for
optimal rig-selection and design
Atlantic regional modeling
- Hurricane impact on mixed layer properties
[Jacob, Shay, Halliwell]
Effects of the entrainment
closure on the oceanic mixed
layer response during a
tropical cyclone passage
Gaspar
MY2.5
Hycom Q Movie
KPP
PWP
PACIFIC BASIN-SCALE SIMULATIONS
- 1/12° in progress [Metzger, Hurlburt]
PACIFIC REGIONAL SIMULATIONS
- 1/8° to 1/32° Japan/East Sea [Hogan, Hurlburt]
- 1/32° East Asian Seas [Hogan]
PACIFIC MODEL CONFIGURATION
• Horizontal grid: 1/12° ( 2294 x 1362 grid points, 6.5 km
spacing on average)
• 20°S to 65.8°N
• 20 vertical coordinates (σ-theta reference)
• Bathymetry: Quality controlled ETOP05
• Surface forcing:
wind stress, wind speed, heat flux (using bulk formula),
E-P + relaxation to climatological SSS
• River runoff
• Buffer zone: ~3° band along southern and eastern
boundary with relaxation to monthly climatological T
and S
• Closed boundaries along 20°S, in the Indonesian
throughflow region and in the Bering Strait
22 x 13 Equal Area Decomposition (all land tiles discarded)
 Running on ------- (MHPCC)
 50,000 hrs/model year on 207 CPUs
 288 GB/model year for 3-D fields every 3 days
 MPI parallelization
1/12° Pacific HYCOM
SSH Snapshot – 17 December
Forced with climatological HR winds and ECMWF thermal forcing
1/12° Pacific HYCOM
SSH and SST Snapshot – 17 December
Forced with climatological HR winds and ECMWF thermal forcing
Mean Sea Surface Height
1/12° Pacific HYCOM vs. Observations
Qu et al. (2001, JPO)
Velocity Cross-section Across Luzon Strait
Sb-ADCP data versus 1/12° Pacific HYCOM in the upper 300m
120.75°E
18.5-22°N
Transport
3.3 Sv
4.4 Sv
Sb-ADCP data from Liang et al. (DSR Part II, in press)
HYCOM is forced with high-frequency HR winds and ECMWF thermal forcing
Velocity Cross-section Along Luzon Strait
Sb-ADCP data versus 1/12° Pacific HYCOM in the upper 300m
118.5-124.5°E
21.0°N
Sb-ADCP data from Liang et al. (DSR Part II, in press)
HYCOM is forced with high-frequency HR winds and ECMWF thermal forcing
1/12° Pacific HYCOM
Impact of Hurricane Julliette
(Zamudio, Hurlburt, Metzger)
SST
SSH
Plans for JES/EAS Modeling [Hogan, Hurlburt]
1/32° Japan/East Sea (ONR JES DRI)
• Branching of Tsushima Warm Current
• Nearshore Branch Dynamics
• Water mass formation (ESIW)
• Model-data comparisons
• Impact vertical coordinate configuration
• Data assimilation
1/32° East Asian Seas (LINKS)
• Ability of HYCOM to robustly simulate shelf (Yellow Sea) and
deep (JES) environment
• Branching of Tsushima Warm Current from the Kuroshio
(where, how, etc.)
• Interaction of coastal and large-scale currents
Japan/East Sea
Japan/East Sea
1/8˚
Surface
1/16˚
Surface
Japan/East Sea
1/16˚
Deep
1/32° HYCOM East Asian Seas Model
Nested inside 1/8° HYCOM Pacific Basin Model
Boundary conditions via one-way nesting
and 6 hrly ECMWF 10 m atmospheric forcing
JES summary
JES HYCOM is running with high horizontal grid resolution
and synoptic wind and heat flux forcing
Substantial improvement (especially in separation latitude
of western boundary current) as horizontal grid resolution
increased from 1/8° to 1/32°
Flow over the shelf along the Nearshore Branch
Winter – barotropic – topographic steering
Summer – baroclinic – isopycnal outcropping
HYCOM able to simulate formation and spreading of East Sea
Intermediate Water, most appears to be formed in northern
JES, but some formed locally near Vladivostok
INDIAN OCEAN REGIONAL SIMULATIONS
Arabian Sea model configuration [Baraille]
• (34°E-76°E) ; (10°N-30.3°N)
• 16/20 layers, 1/4° horizontal resolution
• Initial condition extracted from the global MICOM model (Bleck)
• Bimonthly relaxation fields extracted from the global MICOM model
applied at the south boundary, in the Gulf of Aden and in the Gulf of
Oman
• 4-year integration with monthly-averaged ECMWF forcing fields
• Integration since 01/01/2000 with high frequency forcing (6 hours)
• Assimilation of altimetry since 11/01/2001
(mean SSH provided by O. M. Smedstad)
10 day forecast
01/31/2001
Sea Surface Height
Sea Surface Temperature
Density field at 20N
GLOBAL SIMULATIONS
- HYCOM/MICOM comparison (100-year simulation)
for quasi-global domain (northern boundary at 65° N)
at 2° resolution. [“An oceanic general circulation model
framed in hybrid isopycnic-cartesian coordinates” by
R. Bleck (available on web site)]
- Fully global in progress: target resolution 1.4° for
reanalysis [D. Bi, R. Bleck, A. Wallcraft].
- GODAE intensive period: 1/12° in North Atlantic and
North Pacific, .72° elsewhere.
- 1/12° everywhere in 2005.
HYCOM GLOBAL CONFIGURATION
• A Mercator mesh of
resolution 2ºx2º
(cos(φ)) is used
south of 60ºN. At this
latitude, the Mercator
projection smoothly
transitions to a
bipolar projection
with poles over
Canada and Siberia,
but without grid
singularity over the
ocean area.
HYCOM GLOBAL CONFIGURATION
HYCOM GLOBAL CONFIGURATION
•
HYCOM global version
(GLBx2.00) represents
the ocean by 26 layers
vertically, using σ0
(potential density
referenced to the sea
surface) as vertical
coordinate in the ocean
interior. However,
coordinate surfaces level
off to become constantdepth surface wherever
the isopycnals they
follow outcrop at the sea
surface.
This figure shows a snap
shot of the layers along
the 20ºW meridian.
HYCOM GLOBAL CONFIGURATION
Experimental Design
• Surface forcing: COADS monthly atmospheric
climatology, including wind stresses, wind speed,
solar radiation, net radiation, moisture, etc.. No
fresh water flux (E-P) is applied. In stead, the sea
surface salinity is relaxed to Levitus climatology.
• Initialization: the model ocean is initialized with
the Levitus climatology, i.e., monthly salinity and
temperature.
• Sea ice: Energy load.
• Mixed layer: KPP
• Integration duration: 38 years.
HYCOM GLOBAL CONFIGURATION
Surface features
• Sea Surface Height
(annual mean and seasonal cycle)
• Mixed layer thickness
(annual mean and seasonal cycle)
• Surface heat flux
(annual mean and seasonal cycle)
• Sea ice concentration
(annual mean and seasonal cycle)
HYCOM GLOBAL CONFIGURATION
Water mass properties
• Surface distribution:
SST (annual mean and seasonal cycle)
SSS (annual mean and seasonal cycle)
SSD (annual mean and seasonal cycle)
• Vertical structure (zonal average)
Temperature (annual mean and seasonal cycle)
Salinity
(annual mean and seasonal cycle)
Stratification (annual mean and seasonal cycle)
HYCOM GLOBAL CONFIGURATION
Horizontal currents
• Mixed Layer Velocity
Annual mean and Seasonal cycle
• Horzontal currents at 1000m depth
Annual mean and Seasonal cycle
The main source of data is
provided by altimetry
(see presentation by Thacker/Lee
for in-situ data assimilation)
Altimetry gives an estimation
of the surface circulation
- Optimal Interpolation with vertical projection either by
using isopycnal modes or Cooper-Haines (NRL, SHOM,
RSMAS)
- Ensemble Kalman Filter (EKF) (NERSC)
- Single Evolutive Extended Kalman (SEEK Filter) (LEGI)
- Reduced Order Adaptive Filter [ROAF] (SHOM)
- Reduced Order Information Filter [ROIF] (RSMAS)
Present assimilation system
- 1/3° Atlantic version of HYCOM
- Assimilation of the Modular Ocean Data Assimilation
System (MODAS) optimal interpolated SSH anomalies
from satellite altimetry
- Vertical projection of the surface observations by
Cooper-Haines
- Running in near real-time
1/3° Atlantic HYCOM SSH
20 November 2000
NO ASSIMILATION
Assimilation of MODAS SSH
analyzed fields
Independent frontal analysis of IR observations performed at the
Naval Oceanographic Office overlaid. White line shows the part
of the front being observed within the last 4 days. Black line
shows the part of the front older than 4 days
1/3° Atlantic HYCOM SSH
30 July 2001
Independent frontal analysis of IR observations performed at the
Naval Oceanographic Office overlaid. White line shows the part of the
front being observed within the last 4 days. Black line shows the part
of the front older than 4 days.
Current European project: TOPAZ
Towards an Operational Prediction system for the North Atlantic
and european coastal Zones
Real-time experiment based on EnKF (NERSC) and SEEK (LEGI)
Sea-surface temperature forecast
November 21st, 2001
Sea-surface height forecast
November 21st, 2001
TOPAZ: project participants
•
NERSC:
–
–
–
–
–
•
Coordination
HYCOM model system
EnKF with HYCOM and ecosystem model
Assimilation of ice parameters
Nested model applications
LEGI:
–
–
–
In situ data assimilation
SEEK with HYCOM and ecosystem model
Impact studies
Validation
Based on current
meter moorings
available in Faroe
Shetland Channel
Exceedence plot from Faroe Bank Channel
Deliverables
• Total of 9146 grid points
• One hour time resolution
• Velocity, temp., saln., layer
depth, wind and SLH
• 32.6 Gigabytes per year
• Database is accessed
online on the Internet
• Database with model
diagnostics
Adaptive Filter with HYCOM
(development started on 09/17/2001, R. Baraille)
• Development of the tangent linear model is finished
• We check the validity of the Taylor formula to
determine the window where the approximation is
valid, depending on the size of the initial perturbation.
This work is completed by the definition of a set of
variables (not necessarily the HYCOM variables) which
can vary linearily with time. This problem is adressed
because hybgen is highly non linear.
• The adiabtic adjoint of HYCOM is under developement.
The Reduced Order Information Filter (ROIF)
[Chin and Mariano]
The horizontal (cross-) covariance functions of SSH and
velocities in an extended information filter are
parameterized assecond-order spatial Markov Random
Fields. A vertical projection scheme is used to correct
lower-layer thicknesses and velocities.
How do we define the mean SSH for data assimilation?
OUTREACH
- Live Access Server (presentation by A.
Srinivasan)
http://hycom.rsmas.miami.edu/dataServer/
-A web-based ocean current reference site
(presentation by A. Mariano and E. Ryan)
http://oceancurrents.rsmas.miami.edu