Using GLDAS/LIS to DeriveOptimal Land States for

CFS/Noah Initialization in CTB

1988 1993

July

Jesse Meng, Kenneth Mitchell, Helin Wei, and Jon Gottschalck

Jesse.Meng@noaa.gov

When do we need initialization?

Cold start a new simulation e.g., flood, drought

Model upgrade e.g., physics, parameters, resolution

Model bias constrain• coupled – e.g., 4DDA, Reanalysis• uncoupled – e.g., GLDAS

CFS

Current CFS T62 25-year hindcast OSU LSM Initial land states from Global Reanalysis 2 (GR2)

- T62, 25-year reanalysis, OSU LSM

Anticipated in Next-Generation CFS T126 25-year hindcast Noah LSM Initial land states from Global Reanalysis 3 (GR3)

- T126, 25-year reanalysis, Noah LSM** ** Not yet available

While awaiting coupled GR3: Uncoupled T126 GLDAS with Noah LSM will provide 25-year initial land states for T126 CFS/Noah

Horizontal Resolution• T62 (194 x 94) T126 (384 x 190)

Land component vertical resolution• 2 soil layers (10, 190 cm) 4 soil layers (10, 30, 60, 100 cm)

OSU LSM Noah LSM• Addition of frozen soil physics• Improved physics:

snowpackevaporationground heat fluxinfiltration & runoff

Precipitation forcing: • Both use CPC CMAP precipitation, but different methodology

Other non-precip surface forcing:• Both from GR2

GR2 vs GLDAS

NCEP Reanalysis2 2-Layer Soil Moisture00Z 01 Jan 1979

0-10 cm 10-200 cm

T62

GLDAS also needs a cold start initial condition

GLDAS 4-Layer Soil Moisture(mapped from GR2 for 01 Jan 1979 cold start)

0-10 cm 10-40 cm

40-100 cm 100-200 cm

T126

GLDAS 4-Layer Soil Moisture(after 5-year spinup with repeated 1979 GR2 forcing)

0-10 cm 10-40 cm

40-100 cm 100-200 cm

T126

NCEP Reanalysis2 vs GLDAS spinup

GR2/OSU

GLDAS/Noah

January

NCEP Reanalysis2 vs GLDAS spinup

JanuaryGR2/OSU

GLDAS/Noah

NCEP Reanalysis2 vs GLDAS spinup

JulyGR2/OSU

GLDAS/Noah

CONUS SubRegions

Vol. Soil Moisture 0-10cmFive annual cycles spinup of 1979

Vol. Soil Moisture 10-40cmFive annual cycles spinup of 1979

Deeper soil layers require longer spinup

Vol. Soil Moisture 40-100cmFive annual cycles spinup of 1979

Deeper soil layers require longer spinup

Vol. Soil Moisture 100-200cmFive annual cycles spinup of 1979

Has bottom soil layer in the West fully spunup?

Vol. Soil Moisture 0-200cmFive annual cycles spinup of 1979

Purpose: Create a 6-hourly global land-only precipitation dataset primarilybased on rain gauge observations

Datasets: CMAP Spatial: 2.5° x 2.5°, Temporal: PentadGTS land only Spatial: 0.5° x 0.5°, Temporal: DailyGR2 Spatial: 2.5° x 2.5°, Temporal: 6-hourly

Approach: (1) Disaggregate CMAP pentad precipitation to daily 0.5° x 0.5° resolution

using the GTS dataset(2) Disaggregate dataset created in (1) to 6-hourly 0.5° x 0.5° resolution

using GR2 dataset

For both (1) and (2) above: (a) Higher temporal resolution data is summed for the lower temporal resolution data period(b) Weights are calculated for each period of the higher temporal resolution data(c) These weights are applied to the lower temporal resolution data(d) Additional rules:

• If precipitation for the lower temporal resolution data > 0 but the precipitation of the higher temporal resolution data is = 0, a search is conducted in a 5° x 5° area starting from the inside out to find a suitable weight.

• If precipitation for the lower temporal resolution data = 0, final precipitation is = 0

References: Xie P., and P. A. Arkin, 1996: Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 2539-2558.

Optimal Precipitation Forcing

GR2 CMAP

CONUS SubRegions

Daily Precipitation [mm]1979

GR2 CMAP

25-year simulation forced withGR2 + CMAP

Total Column Vol. Soil Moisture (0-200cm)25 years (1979-2003)

GR2 GLDAS

Vol. Soil Moisture Anomaly 0-200cm1979-2003

GR2 GLDAS

Vol. Soil Moisture 4 Layers1979-2003

Vol. Soil Moisture 4 Layers1979-2003

Northern Central US

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July 1988

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July 1988anomaly

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July 1993anomaly

Summary 25-year T126 GLDAS/Noah land states

forced with GR2+CMAP Resulting soil moisture structure is

different from GR2/OSU Results will be used to initialize

CFS/Noah hindcast testing Plan:

• Implement Higgins/Shi CPCCONUS+Mexico gauge-only daily precip

• Spinup strategye.g., annual or monthly cycles

• Initialization strategye.g., anomaly rescaling

Thank you!

Jesse.Meng@noaa.gov

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

April

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

October

NCEP Reanalysis2 vs GLDAS spinup

JulyGR2/OSU

GLDAS/Noah

1988 1993

GLDAS/Noah Total Soil Moisture

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July 1988

GLDAS/Noah 4-Layer Soil Moisture

0-10 cm 10-40 cm

40-100 cm 100-200 cm

July 1993