# Presentation: 082754

## CFS03—effects of coupling to ocean model and of increasing vertical resolution in atmospheric model

***--much better simulation in coupled mode with 64 than with 28 levels in atmospheric component***
***--differences between 28 and 64 levels show up much more in coupled mode***

## 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**

## Warmer SST

- Differences in 23 yr coupled runs
- 64 minus 28 level atm. model

- More downward short wave

- Fewer stratus clouds

## 23 year coupled runs

- 64 level atmos. model lacks stratus clouds

*23 year coupled runs*

- 28 levels

- 64 levels

## 23 year mean precipitation

***23 year mean precipitation***

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

- CMAP

- 28 levels coupled

- 64 levels
- coupled

## Slide 7

## Forced with observed SST

**Forced with observed SST**

**Coupled to ocean model**

***28 levels***

***64 levels***

## Slide 9

## Surface stress Pacific

- 22 years FSU obs estimates
- 23 year coupled runs

- FSU

- 28 levels

- 64levels

## Too strong meridional stress with 28 levels

***Too strong meridional stress with 28 levels***

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

- Ekman pumping

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

*East Pacific*

*Equator*

## Amip runs 23 year integrations of atmos model with observed SST

**Amip runs 23 year integrations of atmos model with observed SST**

***Coupling atmos model to ocean model strengthens stress in 28 level atmos model, decreases stress in 64 level model.***

## 28 layer coupled version stronger stress than others

## 28 levels—too cold SST, too much  Ekman pumping

## 64 levels—less cold bias in SST, less Ekman pumping

## Increased Ekman pumping and more upwelling at equator in Pacific with 28 than with 64 levels, probably associated with stronger Pacific ITCZ with 28 levels;  doesn’t explain warmer tropical SST in Atlantic

***2)  Less marine stratus with 64 levels compared to 28 levels; more short wave in eastern oceans, possibly warming SST which are advected to equator.***

## 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

## Evaporation, surface net shortwave in NCEP global model stronger than independent estimates

## Global model has 10-20 W/m2 more evaporation, 

- NCEP global model

- Independent estimates

***Global model has 10-20 W/m******2****** more evaporation, ***
***20-30 W/m******2****** more net shortwave***

- NCEP global model

- Independent estimates

## Differences in 1st month of integration

***Differences in 1******st****** month of integration***

## Development of differences between 28 and 64 levels in 1st year of integration

- Development of differences between 28 and 64 levels in 1st year of integration

- 64 levels—warmer SST, less Ekman pumping in Pacific, more downward heat flux in east Pacific, Atlantic

## SST differences first 3 months

- 64 -28 layers

## Increased Ekman pumping and more upwelling at equator in Pacific with 28 than with 64 levels, probably associated with stronger Pacific ITCZ with 28 levels;  doesn’t explain warmer tropical SST in Atlantic

***2)  Lack of marine stratus with 64 levels compared to 28 levels;  more short wave in eastern oceans, possibly warming SST which are advected to equator.***