Tolman and Behringer, June 10, 2009GOVST 1 st meeting, 1/33 National Report (NOAA/NCEP) RTOFS, CFS,...

Tolman and Behringer, June 10, 2009

GOVST 1st meeting, 1/33

National Report (NOAA/NCEP)RTOFS, CFS, SST, sea ice

Hendrik L. TolmanChief, Marine Modeling and Analysis BranchNOAA / NWS / NCEP / EMC

[email protected]



intro

The bigger pictures: Representing NCEP here, not necessarily all of NOAA:

GFDL ocean modeling in climate realm. AOML push to do ocean OSSEs.

Mandate within NOAA to build NOAA part of a national ocean modeling backbone capability (real time and short term forecast focus?):

A part of a larger national backbone capability with main contributions from Navy, and many other partners.

Within NOAA: NCEP : global focus: NOS: National coastal focus (Coastal Ocean

Modeling Framework). IOOS RA’s regional focus.



intro

Cont’ed: Second focus for us on ocean-weather link.

Hurricane forecast problem. General weather prediction.

NCEP focus on short term weather up to annual. Seamless model suite approach (see next slide).

Resources: Funding remains issue, hurricane helps (HFIP). Building capability. HYCOM consortium.

Stand-alone SST and ice products. GODAS in CFS ongoing GODAE contribution. Ecosystems Modeling Enterprise in NOAA a 20 year plan

under development.



NCEP Operational Global Weather-Climate (“Seamless”) Forecast System July 23, 2007

A. Operational forecasts

1. All forecasts are Atmosphere-Land-Ocean coupled 2. All systems are ensemble-based except daily, high-resolution run 3. All forecasts initialized with LDAS, GODAS, GSI from GFS initial conditions 4. Physics and dynamics packages may vary

a. Anticipated that the weekly forecast will have most rapid implementations and code changes, seasonal configuration may be one (or at most two) versions behind weekly

Forecast Product

Number of members per refresh period

Runs/day Membership refresh period

Horizontal resolution (ratio, current value)

Forecast Length

Initialization technique

Computing resource

ratio* Daily-hires 1 4 daily 1.0, T382 15 days GSI 1.0

Weekly 80 80 daily 0.5, T170 15 days ET breeding 2.5

Monthly 56 8 weekly (7 days)

0.5, T170 60 days ?? 1

Seasonal 60 2 monthly 0.33, T126 1 year Lagged analysis 2x daily

0.44

Calculated from ratio of runs/day * forecast length * expense of each forecast#

# expense ratio is resolution**3

Adapt this vision to ocean modeling.

Add ocean to each time scale.

Executing the weather-climate strategy

intro



intro

Ocean modeling at NOAA – NCEP ; Eddy-resolving real-time short term forecasting ; Real Time Ocean Forecast System (RTOFS). HYCOM based (part of HYCOM consortium). Jan. 2007 workshop identified four focus areas for NCEP:

Eddy resolving modeling (1) and model initialization (2). RTOFS – Atlantic RTOFS – Global

Coupled high-resolution modeling of hurricanes (3). RTOFS - HWRF ( - WAVEWATCH IIITM) coupling.

Coupled modeling of weather in general (4). Coupled CFS for reanalysis and re-forecasting

(GFS + MOM4 from GFDL, GODAS). GFS + HYCOM ? Low hor. res., high vert. res.



ROTFS-Atlantic

1/12º resolution Real Time Ocean Forecast System for North Atlantic Ocean. (RTOFS-Atlantic, HyCOM based). Deterministic 6 day forecast (including tides, 3h forcing). Assimilation of most available data with in-house

assimilation schemes (2+1D Var, recursive filtering). Run once per day.

Presently in bad shape, issues are dealing with operations, not with science: Most difficult computer update in decade results in nine-

month upgrade moratorium. Weather operations practices versus ocean needs.

Data density and impacts for assimilation approaches. Re-initializations, interactive QC.

In queue for summer upgrade



RTOFS-Global

Global eddy resolving model needed at NCEP for various reasons: Provide OPC with suitable guidance. Key element of NOAA and national backbone capability.

NCEP – NOS – IOOS strategy. Address boundary issues with RTOFS - Atlantic. Enable local coupled modeling for hurricanes at NCEP.

Focus on North Atlantic and North East Pacific, but enable globally as needed (unified model approach).

Enable ecosystems modeling in general. NOAA mandate dating from 2005. Gap needs to be filled, Resources:

Compute, storage, visualization and analysis, Human.



RTOFS-Global

Cont’ed: Leverage HYCOM consortium work to accelerate filling gap.

Adopt Navy 12° global HYCOM model as starting point. 2009 computing resources sufficient to run model,

not sufficient to fully support initialization.Run model with NCEP forcing and Navy

initialization, daily 6 day forecast.Operational data feed being established.Visualization and validation is an issue.

2012 computing resources to fully support system.NCEP self contained initialization.Envision close collaboration with Navy in

development of assimilation / initialization. 2014+ decision needs to be made to go to higher

global resolution or regional US resolution.



HWRF-HYCOM

Coupled HWRF-HYCOM system: Ocean state is important in hurricane track and intensity

forecasting: SST (26°C cut-off). Depth of mixed layer, temperature gradient below. Operational system uses “ad-hoc” POM mode.

HWRF-HYCOM system designed to fit into operational RTOFS-Atlantic model.

Full 3D ocean model. Realistic initialization from operational RTOFS-Atlantic.

Goals and time lines: Parallel testing 2009 Atlantic Hurricane season. Working on adding wave coupling (WAVEWATCH III), to

be tested in parallel operations 2010 or 2011.



meld

ATMOS.:

HWRF

O(9 & 27 km)

OCEAN:

HYCOM–Regional:

O(8~14 km)

RTOFS-Atlantic

(HYCOM–Basin):

O(4~17 km)

IC

Feature Model Wind

Data Assimilation (SST, SSH, T&S) using 2D/3DVAR

BC

SST

* Wind-stress* Heat Fluxes* Precipitation* Atm. Pressure

Coupled HWRF- HYCOM system

GFS: O(25 km)





Simulation Simulation

forfor

KatrinaKatrina

Compared with

Animation of hourly GOES SST 3-day moving average

(http://svs.gsfc.nasa.gov/vis/a000000/a003200/a003222/index.html)

Example of coupled simulations conducted for 2008



HWRF-HYCOM

subinertial waves

Cold wake

Real time testing for 2008 hurricane

season (Ike).

Realistic oceanic simulation and response to a

storm!



HWRF-HYCOM

Focus areas for model development:

First and foremost this is a hurricane forecast problem: Hurricane track and intensity

Sustained progress can only be made with solid science. Evaluate ocean model skill to accurately represent

processes of interest. Evaluate hurricane forecast system to provide accurate

air-sea fluxes. Evaluate the ability of observations and data

assimilation to accurately represent initial conditions in regions and for state variables of interest.



HWRF-HYCOM

Katrina

Rita

Gustav Kyle

Mean Difference is at the same order of magnitude;Variations are consistently smaller

Black – HYCOM

Red – Ops (POM).

Track errors



HWRF-HYCOM

Mean Difference is at the same order of magnitude;Variations are consistently smaller

Intensity errors

Katrina Rita

Gustav Kyle



HWRF-HYCOM

Time

Po

siti

on

SST cooling varies locally, what will be a good metric for cooling:

local

area

footprint

A

B 6-hour after6-hour before

Size: 34-kt



HWRF-HYCOM

The Size of the footprint matters!

R=150-km

R<=50-kt

ΔSST ~0.7oC

ΔSST ~0.8oCR<=34-kt

ΔSST ~0.4oC



HWRF-HYCOM

150-km34-kt

Examples of fluxes and averaging radii for metrics …



HWRF-HYCOMPre-storm survey (Gustav)

Model: warmer SST and deeper MLD, Z26 and Z20 ICIC



Current Operational GODAS

• Operational in 2003.

• Based on MOMv3 (1o x 1o, 1/3o in the tropics, 40 lvls) and a 3DVAR assimilation scheme.

• The assimilation data are temperature profiles (XBT, Argo, TAO, TRITON, PIRATA), synthetic salinity profiles derived from a climatological T-S relation and Jason-1 altimetry (March 2007). The data window extends from 2-weeks before to 2-weeks after the analysis date.

• Atmospheric forcing from the NCEP Reanalysis-2, surface relaxation to Reynolds weekly OIv2 SST, Levitas climatological SSS.

• Ocean reanalysis (1980-present) providing initial conditions for retrospective CFS forecasts used for calibration.

• Two versions associated with the CFS: 14-day lag, 1-day lag.

• A third stand-alone version with a 14-day lag.



Current Operational SI Prediction at NCEP

ClimateForecastSystem(CFS)

Ocean ModelMOMv3

quasi-global1ox1o (1/3o in tropics)

40 levels

Atmospheric ModelGFS (2003)

T6264 levels

GODAS3DVAR

XBTTAO etc

ArgoSalinity (syn.)

TOPEX/Jason-1

Reanalysis-23DVART62L28

update of theNCEP-NCAR R1



Next Generation GODAS in the CFSRR

• To become operational in 2010.

• Based on MOMv4 (1/2o x 1/2o, 1/4o in the tropics, 40 lvls) and an updated 3DVAR assimilation scheme.

• Assimilation data are temperature profiles (XBT, Argo, TAO, TRITON, PIRATA), synthetic salinity profiles derived from a seasonal T-S relation, and TOPEX/Jason-1/Jason-2 Altimetry. The data window is asymmetrical extending from 10-days before the analysis date.

• Surface temperature relaxation to (or assimilation of) Reynolds new daily, 1/4o OIv2 SST, surface salinity relaxation Levitas climatological SSS.

• The analysis system is coupled to the CFS in the sense that the first guess for the assimilation is provided by the CFS. After each analysis cycle the ocean model is stepped forward as a fully coupled component of the CFS.

• The current stand-alone operational GODAS will be upgraded in 2009 to the higher resolution MOMv4 and be available for comparison with the coupled version.



CFSRR at NCEP

GODAS3DVAR

Ocean ModelMOMv4

fully global1/2ox1/2o (1/4o in tropics)

40 levels

Atmospheric ModelGFS (2007)

T382 64 levels

Land Model Ice Mdl SISLDAS

GDASGSI

6hr

24hr

6hr

Ice Ext6hr

Climate Forecast System



http://www.cpc.ncep.noaa.gov/products/GODAS/

GODAS access – CPC site

• Pentad and Monthly data products

• 1979-present

• Access to current and archived Monthly Ocean Briefings



http://cfs.ncep.noaa.gov/ncep_data/

GODAS access - NOMADS

• Pentad and Monthly data

• Interactive plotting

• ftp, http – full data file download

• ftp2u – partial data download

• DODS



HYCOM - GFS

Looking into coupling HYCOM to GFS for weather – climate strategy: Lower horizontal resolution, but high vertical resolution to

be able to describe interaction physics. ESMF – NEMS based, focus on coupling.

Initialization initially by CFS / GODAS. Tentatively upscaling of hi-res global.

Utilizing ensembles to design assimilation systems.

Lowest priority for us given limited resources.



SST

Daily Real-time global SST (RTG_SST_HR) analysis (1/12º latitude, longitude resolution) is generated every 24h

(22:30 UTC) using latest 24 h of real-time data. Focus intended on coastal and inland waters.

Daily Real-time global SST (RTG_SST) analysis (1/2º latitude, longitude resolution) is generated every 24h

(22:30 UTC) using latest 24 h of real-time data.

Validation statistics available on WEB page. Recent issues and changes:

Various instrument transitions. Ice edge issues have been removed. Coastal issues related to physical retrievals being addressed.



SSTSST

New polar views available on web site.

Large polar biases have been removed (2009 Q1)

Coastal biases still an issue



sea ice

Northern and Southern Hemisphere daily ice

concentration products based on SSMI data, including SSMI based

weather filtering of data.

+ AMSR



sea ice

Sea Ice For CFSRR

Daily, global 0.5º latitude-longitude 26 October 1978 to present Combines data from

Canadian Ice Service (Laurentian Lakes). GLERL (Great Lakes). National Snow and Ice Data Center / GSFC (most of

globe) through 1996/12/31. NCEP operational analysis from 1997/01/01 (global)

To produce a continuous, consistent, high quality series of sea ice concentrations matching to the present day's operational analysis system.

Produced 2007, refined 2008, 2009.



sea ice

Sea Ice in RTOFS / HYCOM :

Work starts on low-resolution global model (ESMF). Partially motivated by sea ice forecast issues in CFS. Coupled and stand-alone versions:

Stand alone useful considering resource ratio HYCOM – ice.

Stand-alone to be used for assessing flux errors in GFS. Dynamic-thermodynamic ice with multiple thickness

classes. Using operational concentration analyses.



SST and sea ice

SST and sea ice are “stand alone” products

Will remain so and will be maintained and developed for the foreseeable future:

Input for weather models. Independent validation products.

Additional products will become available from modeling: SST directly from HyCOM. Ice model embedded in global HyCOM.

Data products can benefit from, or be merged with models: SST to follow model trends rather than revert to

climatology for areas with prolonged absence of observation data.

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