# Presentation: 927319

## THE NEW SEASONAL FORECAST MODEL AT NCEP

**3.8**

**S. Saha, W. Wang, D. Behringer, S. Nadiga, H.-L. Pan and Glenn H. White**
**Global Climate and Weather Modeling Branch**
**Environmental Modeling Center**
**National Centers for Environmental Prediction**
**DOC/NOAA/NWS**
**Camp Springs MD**
**Glenn.White@noaa.gov**

## Climate CFS03 (Climate Forecast System) to be implemented Aug. 24--monthly, seasonal forecasts out to 10 months dailyAtmospheric component--operational global weather model (GFS03) of 2003 at T62, 64 levels Ocean component--GFDL MOM3no flux correction

**Climate CFS03 (Climate Forecast System) to be implemented Aug. 24****--monthly, seasonal forecasts out to 10 months daily*****Atmospheric component--operational global weather model (GFS03) of 2003 at T62, 64 levels ******Ocean component--GFDL MOM3*****no flux correction**

## Seasonal Forecasting at NCEP

- Assimilation
- System (ODAS)
- OGCM
- 3D VAR

- Coupled Ocean
- Atmosphere
- General
- Circulation
- Model
- (CGCM)

- Ocean Initial
- Conditions

- SST Forecast

- US Forecasts
- Surface Temp
- Precip

***Seasonal Forecasting at NCEP***

- NCEP-2
- Atmospheric
- Initial
- Conditions

- NCEP2 fluxes

- NCEP-2 Fluxes

## 23 years of hind-casts to provide a) bias corrections b) monthly mean skill estimates for real-time forecastseach month of 23 years has nine-month seasonal forecast with 15 ensemble members--3 initial ocean states--5 initial atmospheric states centered around each ocean initial stateover 3000 years of coupled model integration23-year ocean reanalysis 1981-present    

## Changes developed for this implementation:

**--New improved global ocean data assimilation**
**--New improved global coupled model **
**--New improved global atmospheric model **
**--Coupled hind-casts**
**--One-tier system**
**--NCEP-2 initializes forecasts and hind-casts**
**--New ensemble procedures**

## Climate drift with 28 levels

**Climate drift in SST in 23 year coupled runs**

***Climate drift with 28 levels***

***Climate drift with 64 levels***

**Much less drift along equator with 64 levels**

## Coupled Model Simulation 

**Coupled Model Simulation**
- SST Interannual Variability

**Observed**

**64 Level Atm**

**28 Level Atm**

## 23 year mean precipitation

***23 year mean precipitation***

***More intense Pacific ITCZ with 28 levels***

- CMAP

- 28 levels coupled

- 64 levels
- coupled

## Surface stress Pacific

- 22 years FSU obs estimates
- 23 year coupled runs

- FSU

- 28 levels

- 64levels

## Ekman pumping

**Ekman pumping**

***28 level run has too much upwelling along equator in Pacific***

***East Pacific***

## Simulation 

**Simulation**
**ENSO SST cycles**
- Nino 3.4 SST
- Anomalies
**Simulated**
- 2002-2040 (top)
**Observed**
- 1965-2003
- (bottom)

## Examples of ENSO events

**Examples of ENSO events**

- Simulated El Nino 2015-2016

- Simulated La Nina 2017-18

- Real El Nino 1982-1983

- Real La Nina 1988-1989

## 25 season sample

**25 season sample**

## Slide 14

## Slide 15

## Slide 16

## TOOLS VS SIGNALS

- TOOL RELIABILITY:** o** ~ 70-100%	        **o** ~ 30-70%	  **o** ~ < 30%

- CPC Evaluation of Forecast Tools

## Conclusions

***38 year Coupled Ocean-Atmosphere run gives low tropical SST bias, realistic ENSO, MJO activity***
***64 level atmospheric model appears to perform much better in coupled mode than 28 level atmospheric model***
***New system has more skill than old seasonal forecast system***
***Hind-casts and CMIP integrations will be made available to research community***

## Future Work

***Basic predictability research needed on all forecast scales from 7 days to 12 months***
***Can assess with hind-casts***
***Replacement to CFS03***
***	******-introduction of MOM4***
***	******-sea-ice model and analysis***
***	******-improved stratus clouds***
***	******-higher resolution***
***	******-new reanalysis***
***	******-land model***

## Hypothesis--

***Over last 10 years considerable effort at EMC in improving tropical analyses and short-range forecasts has produced good atmospheric model for seasonal forecasts of equatorial Pacific SST.***
**Better hurricanes         Better ENSO**
**Moral--**
***Don’t separate weather and climate.***