Recent and planed NCEP climate modeling activities

Hua-Lu Pan

EMC/NCEP

EMC is considering the following upgrades to the operational CFS

1. Reducing the 8-lag in the initial condition to a 1-day lag.

2. Introducing 2 new members at higher resolution (T126L64) out to 60 days only. These 2 members would initiate from the same initial condition as the operational two T62L64 members.

Both these upgrades would aim to improve upon the week 3-6 / monthly forecast leads.

NAO – PNA SKILL

CFS Operational T62L64 Forecasts

MAR2005 – FEB2007

2 IC at Day 1-7 of each of the 24 months

Forecast lead times 1-45 days

Negative skewness in observations

Daily skill scores

Averaged over 14 forecasts per monthafter forecast lead time of 8 days

Studies to prepare for a monthly forecast suite (week3

to week6)• Four-times daily T126 version of the

CFS,

• Runs are made to 60 days in length,

• Daily runs of the hindcasts,

• The test period is 2000-2004.

• The period of the runs are : 7 May – 15 July and 7 Nov – 15 Jan.

Daily

Month-1 Correlation Scores

NAO 33.0 %

PNA 21.3 %

Impact of Coupling

0.6

0.4

Pattern correlation for 2000-2004

Persistence

Persistence

0.6

0.4

Summer

Winter

Pattern Correlation for initialization dates from May to June 2002

June 6th-9th June 6th-9th June 6th-9th

The Predictability Barrier

6-9 June: MJO maximum activity crosses “the Maritime Continent”

March 2005 – Feb 2007

Week 1

Week 3

Week 4

Monthly

Week 2

Longitude

March 2005 – Feb 2007

Week 1

Week 2

Week 3

Week 4

Monthly

0.55 = mean ac of daily forecasts in week 1 range

Initial Month

Suru Saha and Hua-Lu Pan, EMC/NCEP

With Input fromStephen Lord, Mark Iredell, Shrinivas Moorthi, David Behringer,

Ken Mitchell, Bob Kistler, Huug van den Dool and others

Design of the 30-year NCEP

CFSRR T382L64 Global Reanalysis

and T126L64 Seasonal Reforecast Project

(1979-2008)

4 Simultaneous Streams

• Jan 1978 – Sep 1987 9 years• Oct 1985 – Sep 1994 9 years• Oct 1992 – Sep 2001 9 years• Oct 1999 – Sep 2008 9 years

2-year overlap for ocean and land spin ups

Total of 36 years of Reanalysis

NCEP CFSRR SLIDE - 1

• Atmospheric T382L64 (GSI) Analysis at 0,6,12 and 18Z

• Ocean and Sea Ice Analysis (GODAS) at 0,6,12 and 18Z

• From each of the 4 cycles, a 9-hour coupled guess forecast (GFS at T382L64) is made with hourly coupling to the ocean (MOM4 at 1/4o equatorial, 1/2o global)

• Land (GLDAS) Analysis with Noah at 0Z

• Coupled 2-day forecast from initial conditions from every cycle, or coupled 5-day forecast from every 0Z cycle (starting every year from 1 Jan 00Z) is made with the T382L64 GFS with hourly coupling to the ocean (MOM4 at 1/4o equatorial, 1/2o global) for sanity check.

ONE DAY OF REANALYSIS

NCEP CFSRR SLIDE - 3

1 year T126L64 coupled forecast ( GFS + MOM4 + Noah )

CFS REFORECASTS

1 Jan 0Z 2 Jan 6Z 3 Jan 12Z 4 Jan 18Z 6 Jan 0Z

Coupled one-year forecast from initial conditions 30 hours apart is made for 2 initial months (April and October) with the T126L64 GFS with hourly coupling to the ocean (MOM4 at 1/4o equatorial, 1/2o

global). Total number of forecasts = 28 x 2 x 30 = 1680

For each cycle, there will be approximately 7 members per month, with a total of 210 members over a 30-year period. This ensures stable calibration for forecasts originating from each cycle, for a given initial month

NCEP CFSRR SLIDE - 4

Example : Skill Estimation for the Initial Month of February

In real time operational prediction, the latest members would be used. For instance, the earliest forecasts release for CPC would be the 15th of the month. Therefore, all members up to the 9th of the month would be used since operations would run in near real time.

For skill estimation, the following 16 members would be used for February starts (going backwards) :

Feb 8 18z, Feb 7 12z, Feb 6 06z, Feb 5 00z, Feb 3 18z ……Jan 21 00z

This includes 4 days of 4 different cycles (Jan 21 0z – Feb 8 18z), smoothly separated by 30 hours. This is in contrast to the present system, where we use 15 members from Jan 9 00z – Feb 3 00z, in 5-day chunks.

NCEP CFSRR SLIDE - 5

CFS REFORECASTS