Analysis Systems. What is the purpose of analysis systems? - To combine available observations, climatological data, and other analyses into one consistent picture, and to derive non-observed fields such as sound velocity from observed fields such as temperature and salinity.
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What is the purpose of analysis systems?- To combine available observations, climatological data, and other analyses into one consistent picture, and to derive non-observed fields such as sound velocity from observed fields such as temperature and salinity.
Analysis systems do not make predictions or forecasts.
Primary contacts: Dan Fox (NRLSSC), Martin Booda (NAVO)
MODAS was developed at the Naval Research Lab at Stennis Space Center in the 1990’s (Fox et al., 2002). It is currently used in a stand-alone mode and also to initialize a relocatable version of the Princeton Ocean Model. A subset of the full capabilities is available for use on submarines.
Analysis system that uses optimal interpolation to incorporate MC-SSTs, SSH from satellite altimetry, T and S data from profilers (XBTs and CTDs) and fixed or drifting buoys, with climatological data to produce 3D T and S fields. 3D sound velocity fields, and associated acoustic parameters, and geostrophic velocity fields, are derived from the temperature and salinity fields.
In water depths greater than the reference level, geostrophic velocities are referenced to the reference level. In water depths less than the reference level, geostrophic velocities are referenced to the bottom, i.e. it is assumed that there is no horizontal pressure gradient at the bottom, which can produce a velocity field that is locally divergent. Strictly speaking, the geostrophic velocity field should be non-divergent.
The reference level is user-selectable. The default is 1000 m.
The EOF scheme used to compress the 3D temperature and salinity output has a limit of 360 grid points in the east-west direction and 181 grid points in the north-south direction. The spatial resolution, in combination with the maximum number of grid points, sets the maximum allowable domain, if the EOF-compressed output is needed.
xmin: longitude at the left edge of the grid (+E, -W)
xmax: longitude at the right edge of the grid
ymin: latitude at the bottom edge of the grid (+N, -S)
ymax: latitude at the top edge of the grid
nx: number of grid points in the east-west
direction (max = 360)
ny: number of grid points in the north-south
direction (max = 181)
E-W grid spacing: dx = (xmax - xmin) / (nx - 1)
N-S grid spacing: dy = (ymax - ymin) / (ny - 1)
# grid ptsE-W dir. nx = 1 + (xmax-xmin)/dx
# grid ptsN-S dir. ny = 1 + (ymax-ymin)/dy
If specifying, dx and dy, program will calculate nx and ny, and GUI will alert user if nx, ny aren’t integers.
From the MODAS 2.1 User's Manual, applies to the GUI-based version.
Try out the Interactive MODAS Grid Calculator
This is not a time-stepping predictive model.
The analysis can be updated at whatever interval the user chooses, but should be based on the availability of new data to assimilate. NAVO’s update cycle is generally once per day.
* Implements “moving covariance” function in MODAS OI
(more continuity of features between tracks)
Courtesy of John Harding, NRL-SSC
Note particularly significant improvement in these areas
Note sampling impact: Red would be green but for this area
Most Accurate Modas First-Guess Field (Bottom Depth < 200 m)
MODAS Seasonal Climatology
MODAS Climatology - MCSST’s
Gulf of Alaska/Eastern Aleutians
Gulf of Cadiz
Central North Atlantic
Greenland/Iceland/ Norwegian Sea
Bay of Biscay/NE Atlantic
Gulf of Oman/Arabian Gulf
Straits of Sicily
Western MedNAVO MODAS areas not using SSH(as of 7/3/02)
SSH and SST
Green line represents
profile derived only
using satellite measured
height and temperature
Decades of edited MOODS profiles are used to derive statistical relationships between surface height and temperature and subsurface temperature and salinity
Relationships are stored on
an irregular mesh, varying
from 1 to 1/8 degree in
resolution to permit high
resolution analyses in shallow
In Situ BT
Courtesy of Dan Fox, NRL-SSC
SSH + SST + Clim
MODAS Validation Example: AXBT Survey
Cold core eddy
MODAS Temperature at 200m
Courtesy of Dan Fox, NRL-SSC
Equatorial Intermediate Water
El Nino affect
North Pacific Intermediate Water
Versions: Central Site, METOC Center, On Scene
Run at NAVOCEANO on SGI Origin, Power Challenge Array, and ONYX systems
Satellite altimetry and MCSSTs plus in situ data
Includes reloctable Princeton Ocean Model
Approx 6 GB of disk space required
MODAS2.1 : NITES-I ASHORE
METOC Center version
All capabilities of above except would normally receive first guess field from NAVO
via TEDS METCAST.
Variable disk space (max 6 GB) depending on desired area of coverage
UNIX systems (HP TAC4, Sun, SGI, PC LINUX, …)
MODAS2.1 : NITES-I AFLOAT (“MODAS/Lite”)
No direct altimetry use. Requires first guess field from MODAS run at Center.
Input/output via TEDS database
Minimal disk space required ( less than 1 GB for global coverage )
UNIX systems (as above)
O 281742Z OCT 98
prgars MODAS2 TEMPERATURE 98301 981028
5 133 1 97
JJXX 28108 0000/ 12930 04800 88888 00275 MODAS
JJXX 28108 0000/ 13000 04800 88888 00276 MODAS
JJXX 28108 0000/ 12830 04830 88888 00292 03291 08290 MODAS
JJXX 28108 0000/ 12900 04830 88888 00283 03282 08281 13280 MODAS
JJXX 28108 0000/ 12930 04830 88888 00279
JJXX 28108 0000/ 12800 04900 88888 00294 03293 MODAS
JJXX 28108 0000/ 12830 04900 88888 00293 03292 08292 13290 18286 MODAS
JJXX 28108 0000/ 12900 04900 88888 00291 03291 08290 13289 18288 MODAS
JJXX 28108 0000/ 12930 04900 88888 00286 03285 08285 13286 18285 MODAS
Byte-Encoded & EOF-Compacted
Temperature/SV (also pushed to
centers, facilities & ships at sea)
OVLY2 of Physical/Acoustic
NetCDF of Temperature/SV/Salinity
ARCVIEW Format (for REACTs)
Currents over Temperature
DSCA, SSCA, MLD, SLD, ZX
Observations Chart (Secret)
Wavelet-compressed fields became available in May 2001
The arrows are parallel to the streamlines everywhere and their length indicates the speed, as referenced to the velocity scale vector. The length of the curved arrow is a function of the velocity all along it's short path - not just at the beginning.
Typical Satellite SSTs of Kuroshio Current (2/19/1996) their length indicates the speed, as referenced to the velocity scale vector. The length of the curved arrow is a function of the velocity all along it's short path - not just at the beginning.
Estimated surface current conditions in Kuroshio area during time period of the MODAS data analysis. Data are from weekly survey reports produced by Japanese researchers. These reports are independent of MODAS calculations, though the same data may be used.
Adapted from Johnson and Broome 1999
Fox, D. N., W. J. Teague, C. N. Barron, M. R. Carnes, and C. M. Lee, 2002: The Modular Ocean Data Assimilation System (MODAS). Journal of Atmospheric and Oceanic Technology, 19, 240-252.
Fox, D.N., C.N. Barron, M.R. Carnes, M. Booda, G. Peggion, and J. Gurley, The Modular Ocean Data Assimilation System, Oceanography, 15 (1), 22-28, 2002a.
Johnson, A. and R. Broome, 1999: Validation Test Report for the Modular Ocean Data Assimilation System (MODAS 2.1), 42 pp.
Naval Research Laboratory, P. S. I., 1999: User's Manual for the Modular Ocean Data Assimilation System (MODAS) Version 2.1. PSI Technical Report S-285.
Primary contact: Webb DeWitt (FNMOC)
OTIS predates MODAS. It was developed at FNMOC in the 1980’s. While it is still being run by FNMOC, it is scheduled to be phased out.
OTIS their length indicates the speed, as referenced to the velocity scale vector. The length of the curved arrow is a function of the velocity all along it's short path - not just at the beginning.http://www.fnmoc.navy.mil/
OTIS has been implemented at FNMOC on a variety of regional (eddy resolving) and global (non-eddy resolving) grids.
Cummings, J. A., C. Szczechowski, and M. Carnes, 1997: Global and regional ocean thermal analysis systems. Marine Technology Society Journal, 31, 63-75.
Documents on FNMOC web site.
Primary contact: Jim Cummings (FNMOC)
3D-MVOI was developed at NRL Monterey in the late 1990’s.
3D-MVOI their length indicates the speed, as referenced to the velocity scale vector. The length of the curved arrow is a function of the velocity all along it's short path - not just at the beginning.
Must match domain of atmospheric or ocean model that it’s being used with.
Ocean Forecast Component their length indicates the speed, as referenced to the velocity scale vector. The length of the curved arrow is a function of the velocity all along it's short path - not just at the beginning. Sequential Incremental Update Cycle Analysis-Forecast-Analysis
MCSST GOES SST Ship SST Buoy SST XBT, CTD PALACE Float Fixed Buoy Drift Buoy Altim SSHA SSM/I Sea Ice
Forecast Fields Prediction Errors
MVOI - simultaneous analysis 5 ocean variables temperature, salinity, geopotential, velocity (u,v)
Courtesy of Jim Cummings, NRL-Monterey
Note that the type and amount of data is subject to change depending on what is available. (Slide is courtesy of Jim Cummings, NRL-Monterey)
Rossby radius of deformation (from Chelton et al. (1998), JPO 28: 433-460). Used as default for horizontal correlation length scales in the 3D-MVOI. Scales range from ~10 km at the poles to ~240 km in the tropics.
Courtesy of Jim Cummings, NRL-Monterey
Cummings, J., 2002. Powerpoint brief.