# Presentation: 926553

##    The Climatology and Interannual Variability of North American Stormtracks in the GFS and CFS Global Climate Models

**       **

**Timothy Eichler and Wayne Higgins**
**Climate Prediction Center/NCEP**

##      T62  GFS  run with AMIP II SST

-      Run from 1950-2002
-      SLP saved twice daily

- GFS Simulation

- CFS Simulation

-      2.5x2.5 fully coupled simulation
-      Run from 2002-2033
-      Free Run (i.e. climate mode)
-      SLP saved twice daily

## I

**I**

**III**

**II**

## a

**a**

**b**

## Storm Track Frequency Difference CFS-GFS

**Storm Track Frequency Difference CFS-GFS**

##                    a-d:  (winter through fall)   

**SLP (hPa) of Storms  I: Obs  II:  GFS  III:  CFS**
**                   ****a-d:  (winter through fall)**

**I**

**II**

**III**

##       (a-d: winter through fall) 

**SLP Diff I: GFS-Obs  II: CFS-OBS    **
**      ****(a-d: winter through fall)**

**I**

**II**

## Standard Deviation Analysis for I: GFS  and II: CFS

**Standard Deviation Analysis for I: GFS  and II: CFS**

**I**

**II**

- a

## Slide 9

## Slide 10

## Slide 11

## Composite Stormtrack Frequency Anomaly for a: Strong El Nino-neutral and b: strong La Nina-neutral 

**a**

**b**

## Composite GFS Stormtrack Frequency Anomaly for a: Strong El Nino-Neutral and b: Strong La Nina-Neutral 

**a**

**b**

## Composite CFS Stormtrack Frequency Anomaly for a: Strong El Nino-Neutral and b: Strong La Nina-Neutral 

**a**

**b**

## Stormtrack difference (Strong El Nino – Strong La Nina) for a: Observations  b: GFS Model  c: CFS Model

**a**

**b**

**c**

## Merdional Temp. Gradient ((degrees C/ km)*100) for a: obs  b: GFS model  c: GFS-obs

**Merdional Temp. Gradient ((degrees C/ km)*100) for a: obs  b: GFS model  c: GFS-obs**

**a**

**b**

**c**

## Merdional Temp. Gradient ((degrees C/ km)*100) for a: obs  b: CFS model  c: CFS-obs

**a**

**b**

**c**

**Merdional Temp. Gradient ((degrees C/ km)*100) for a: obs  b: CFS model  c: CFS-obs**

## H500 Gradient ((m/km)*100) for a: obs  b: CFS model  c: CFS-obs

**H500 Gradient ((m/km)*100) for a: obs  b: CFS model  c: CFS-obs**

**a**

**b**

**c**

## H500 Gradient ((m/km)*100) for a: obs  b: GFS model  c: GFS-obs

**H500 Gradient ((m/km)*100) for a: obs  b: GFS model  c: GFS-obs**

**a**

**b**

**c**

## Conclusions

-       **GFS Produces Stormtrack Climatology spatially reasonable though approximately 50% less frequent...  CFS slightly better.**
**        ****Storm tracks less frequent and weaker especially in the North Pacific and North Atlantic in areas normally associated with strong baroclinicity.**
**       ****GFS and CFS models exhibit a seasonal cycle for stormtracks though weaker than obs.**
**       ****GFS and CFS stormtracks show a response to ENSO evident especially when comparing strong events**
**       ****Reduced storm frequency relative to observed implies weak model variability.  Evidence suggests that the GFS and CFS models have less baroclincity than observed. **

## Future Work

-     **Explore GFS and CFS model physics to ascertain why models’ storm variability is less than observed (e.g. look at surface heat budget)**
-     **Investigate Storm structure (e.g. fronts, precipitation, etc.) to see if they are realistic**
-       **Use stormtracks software on other data:  rr data, ETA model...   Program has potential as a prognostic tool...**