# Presentation: 653615

## GFS Upgrade Implementationscheduled May 1, 2007Scientific Decision Briefing

- Mark Iredell
- Global Climate and Weather Modeling Branch
- April 23, 2007

## Outline

**Scientific Approach**
**Motivation**
**Details of changes**
**Test strategy**
- Retrospective Evaluation
- Real-time Evaluation

## Goals of this GFS implementation

- Unify the NCEP 3DVAR assimilation system under the GSI, improving some performance metrics without affecting others and preparing for future analysis improvements
- Change vertical coordinate to hybrid sigma-pressure, reducing some upper air model errors
- Add new observing systems
- Modernize the radiation package
- Increase output particularly for hydrology

## GFS Implementation changes

- Observation changes
- Full resolution AIRS
- COSMIC GPSRO
- Analysis changes
- GSI (Gridpoint Statistical Interpolation)
- Forcing changes
- None
- Physics changes
- Modularized radiation package
- Dynamics changes
- Hybrid sigma-pressure vertical coordinate
- Infrastructure changes
- None
- Resolution changes
- None
- Post processing and product changes
- Output hourly GDAS files
- Change to internal model history file
- More fields output in model flux file

## Observation changes

- Inclusion of COSMIC GPS-RO refractivities
- Data available to retrospective runs starting November 2006
- Inclusion of every field of view AIRS
- Data available to retrospective runs starting September 2006
- Modifications to quality control other radiances

## Analysis changes

- GSI (Gridpoint Statistical Interpolation) unifies global 3DVAR with the mesoscale system
- Grid point definition of background error
- Use of recursive filters
- More appropriate background errors in the tropics
- Improved code design
- Inclusion of improved balance constraints
- Modified to use hybrid coordinates
- Many future options included but not exercised in this version

## Physics changes

- Modularized radiation package
- Overall restructuring of radiation related programs to help future development and upgrade.
- In RRTM1-LW, minor upgrade of emissivity coefficient. Rare gas absorption effect turned on.
- In aerosol calculation, vertical sigma based structure changed to pressure based structure
- Minor bug correction in cloud related calculation
- Performance of new radiation very close to operational model

## Dynamics changes

- Hybrid sigma-pressure vertical coordinate
- Model surface remain terrain-following in the lower troposphere but become pure pressure surfaces in the stratosphere
- Reduces vertical advection errors and pressure-gradient calculation errors in the upper part of the model
- Data assimilation and physics done on hybrid sigma-pressure coordinate as well

## Vertical coordinate comparison across North America

## Post processing and product changes

- Output hourly GDAS files
- Supports hydrology and other needs
- May be useful in data assimilation
- Change to internal model history file
- Hybrid sigma-pressure vertical coordinate
- Affects downstream codes
- More fields output in model flux file
- Supports hydrology needs
- No effect on downstream codes
- [website here]

## Final testing set

- Retrospective testing
- 15 June 2005 to 5 November 2005http://wwwt.emc.ncep.noaa.gov/gmb/para/paralog.2005tropics_retro_gsihybrid.html
- 31 July 2006 to 5 November 2006 http://wwwt.emc.ncep.noaa.gov/gmb/para/paralog.2006tropics_retro_gsihybrid.html
- 24 October 2006 to 5 February 2007 http://wwwt.emc.ncep.noaa.gov/gmb/para/paralog.200607winter_retro_gsihybrid.html
- Real-time parallel
- NCO started January 2007; in fairly final form about March 1, 2007 to presenthttp://wwwt.emc.ncep.noaa.gov/gmb/para/paralog.gsihybrid.html

## Outline

- Scientific Approach
- Motivation
- Details of changes
- Test strategy
**Retrospective Evaluation**
- Real-time Evaluation

## Overview of objective scores: Summer 2005 and 2006

*** ***
***rms vector wind error in pry at 200 and 850 hPa in tropics reduced ***
***GSI hybrid precipitation over continental US less positive bias, more skill ***
***compared to radiosondes, GSI hybrid temperatures warmer, temperature forecasts improved in lower troposphere in Southern Hemisphere and tropics, improved in upper troposphere tropics ***
***forecast heights fit radiosondes significantly better ***
***bias of 200 hPa winds over East Asia substantially reduced in GSI hybrid***
***GSI hybrid analysed moisture closer to radiosondes***

## 500 hpa height anomaly correlations

|  | op | pry |
| --- | --- | --- |
| NH day 5 | .800 | .811 |
| Day 8 | .474 | .485 |
| SH day 5 | .801 | .794 |
| Day 8 | .534 | .528 |

***500 hpa height anomaly correlations***
***July 1-Nov. 5, 2005***

|  | op | pry |
| --- | --- | --- |
| 200 day 1 | 4.56 | 4.40 |
| Day 3 | 8.01 | 7.61 |
| 850 day 1 | 2.41 | 1.98 |
| Day 3 | 3.77 | 3.37 |

***Tropical rms vector wind error***

## 500 hpa height anomaly correlations

|  | op | pry |
| --- | --- | --- |
| NH day 5 | .818 | .809 |
| Day 8 | .452 | .429 |
| SH day 5 | .761 | .767 |
| Day 8 | .476 | .464 |

***500 hpa height anomaly correlations***
***Aug. 15-Nov. 6, 2006***

|  | op | pry |
| --- | --- | --- |
| 200 day 1 | 4.47 | 4.36 |
| Day 3 | 7.74 | 7.48 |
| 850 day 1 | 2.38 | 1.91 |
| Day 3 | 3.71 | 3.30 |

***Tropical rms vector wind error***

## Slide 16

## Slide 17

## Precipitation skill CONUS

|  | op | pry |
| --- | --- | --- |
| 12-36 hr bias | 1.29 | 1.17 |
| Equitable threat score | .377 | .396 |
| 36-60 hr bias | 1.24 | 1.15 |
| ETS | .343 | .357 |
| 60-84 hr bias | 1.19 | 1.15 |
| ETS | .308 | .319 |

***Precipitation skill CONUS***

## Slide 19

## Precipitation skill CONUS

|  | op | pry |
| --- | --- | --- |
| 12-36 hr bias | 1.26 | 1.21 |
| Equitable threat score | .414 | .431 |
| 36-60 hr bias | 1.24 | 1.22 |
| ETS | .384 | .393 |
| 60-84 hr bias | 1.24 | 1.21 |
| ETS | .337 | .339 |

***Precipitation skill CONUS***

## Slide 21

## Slide 22

## Slide 23

## Slide 24

## Slide 25

## Slide 26

## Slide 27

## 2005-2006 Atlantic Season Average Track Error Using The Current Operational and New GFS

**GFDL**

**GFS**

## 120h Track Error Comparing GFDL  and GFS Model With Current Operational GFS and New HYBRID GFS

**GFDL**

**GFS**

## Much Improved Tracks of Ophelia

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3**

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

## Degraded Philippe Track but Improved Intensity Forecast

**WINDSPEED**
**HYBRID GFDL**

**84 HOURS**

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

## Early and Later Forecasts of Wilma Improved

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

**OLD GFDL (2)**
**NEW GFDL (4)**
**OLD GFS  (1)**
**NEW GFS (3)**

## 2005-2006 Eastern Pacific Average Track Error

**GFDL**

**GFS**

## Overview of objective scores: Winter 2006-2007 PRYC vs OP

***500 hPa heights slightly better in GSI hybrid in NH (.012 anomaly correlation day 5), slightly worse in SH (.004 anomaly correlation day 5) ***
***rms vector wind error in pry at 200 and 850 hPa in tropics reduced; large improvement in 850 hPa tropical winds ***
***GSI hybrid precip over continental US slightly more skill than operational***
***GSI hybrid analysed tropical winds closer to radiosondes; forecast tropospheric winds closer to radiosondes than operational***
***Bias, rms vector error of 200 hPa winds over East Asia substantially reduced in GSI hybrid***
***GSI analysed and forecast extratropical temperatures closer to radiosondes than operational, stratospheric temperatures closer to radiosondes***
***forecast heights fit radiosondes significantly better in GSI hybrid***
***GSI hybrid analysed moisture closer to radiosondes***

- Overview of objective scores: Winter 2006-2007 ***PRYC vs OP***

## 500 hpa height anomaly correlations

***Nov.1 2006-Feb. 05 2007***

***Tropical rms vector wind error***

|  | op | pry | pryc |
| --- | --- | --- | --- |
| NH day 5 | .863 | .874 | .875 |
| Day 8 | .602 | .623 | .628 |
| SH day 5 | .816 | .809 | .812 |
| Day 8 | .520 | .498 | .504 |

|  | op | pry | pryc |
| --- | --- | --- | --- |
| 200 day 1 | 4.58 | 4.42 | 4.36 |
| Day 3 | 7.56 | 7.50 | 7.44 |
| 850 day 1 | 2.36 | 1.84 | 1.83 |
| Day3 | 3.53 | 3.01 | 2.99 |

## Slide 36

## Precipitation skill CONUS

|  | op | Pry | pryc |
| --- | --- | --- | --- |
| 12-36 hr bias | 1.54 | 1.58 | 1.58 |
| ETS | .37 | .36 | .36 |
| 36-60 hr bias | 1.60 | 1.62 | 1.61 |
| ETS | .33 | .33 | .34 |
| 60-84 hr bias | 1.64 | 1.63 | 1.63 |
| ETS | .29 | .30 | .30 |

## Slide 38

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## Slide 42

## Slide 43

## Slide 44

## Winter retro: Precip and 2m Temp (East CONUS)

## Slide 46

## Outline

- Scientific Approach
- Motivation
- Details of changes
- Test strategy
- Retrospective Evaluation
**Real-time Evaluation**

## Slide 54

## Slide 55

## Slide 56

## Slide 57

## ~5 day forecasts from the operational GFS (top left) and the hybrid/GSI GFS (top right) and verifying analysis (bottom) on 1 April 1200 UTC

**~5 day forecasts from the operational GFS (top left) and the hybrid/GSI GFS (top right) and verifying analysis (bottom) on 1 April 1200 UTC**