land analysis in the noaa cfs reanalysis...gr2 1999 cpc 90-day obs precip anomaly ended 30apr1999...

1

Land Analysis in theNOAA CFS Reanalysis

Michael Ek, Ken Mitchell, Jesse MengHelin Wei, Rongqian Yang,

and George Gayno

2

Outline• CFS Reanalysis execution• Land surface model upgrade from OSU to Noah• LIS/GLDAS infrastructure• Observed precipitation forcing• CFSR streams and overlapping• Reanalysis results

– 30-year climatology of global soil moisture field• CONUS regional time series

– Compare to GR2, NARR, and Illinois observations– Spinup, trend, variability, and anomaly

• CONUS May climatology and anomaly

3

0Z GSI 6Z GSI 18Z GSI

0Z GODAS

0Z GSI

CFS Reanalysis Execution (24-hr span) : Note daily GLDAS

6Z GODAS 12Z GODAS 0Z GODAS

12Z GSI

18Z GODAS

Atmos. Analysis

Ocean Analysis

12Z GLDAS6Z GLDAS 18Z GLDAS 0Z GLDAS0Z GLDASLand Analysis

Time

4

5

GFS and CFS: Land Model UpgradeNoah LSM (new) versus OSU LSM (old):

• Noah LSM (vegetation, snow, ice)– 4 soil layers (10, 30, 60, 100 cm)– Frozen soil physics included– Add glacial ice treatment– Two snowpack states (SWE, density)– Surface fluxes weighted by

snow cover fraction– Improved seasonal cycle of vegetation– Spatially varying root depth– Runoff and infiltration account for sub-grid

variability in precipitation & soil moisture– Improved thermal conduction in soil/snow– Higher canopy resistance– Improved evaporation treatment over bare

soil and snowpack

• OSU LSM– 2 soil layers (10, 190 cm)– No frozen soil physics– Only one snowpack state (SWE)– Surface fluxes not weighted by

snow fraction– Vegetation fraction never less than

50 percent– Spatially constant root depth– Runoff & infiltration do not account

for subgrid variability of precipitation & soil moisture

– Poor soil and snow thermal conductivity, especially for thin snowpack

Noah LSM replaced OSU LSM in operational NCEP medium-rangeGlobal Forecast System (GFS) in late May 2005

6

Land Information System

Noah LSM CFSRland analysis

Soil MoistureSoil Temperature

Snow

Land SurfaceCharacteristics

Topography Land Cover

Soil

Non-precipMeteorological

Forcing

PrecipitationForcing

Land VariablesSoil Moisture

Soil TemperatureSnow

CFSR surface file

gdas1.t00z.sfcanl

Christa Peters-Lidard et al., NASA/GSFC/HSB

7

Motivation for Using Observed Precipitation in CFSRGDAS high bias in tropical precip compared to CMAP analysis

10 July – 09 Aug 2007 ExampleDifference Plot

GDAS yields high precip bias in tropics.

8

Unified Daily Gauge Data Dense gauge networks from special CPC collections

over US, Mexico, and S. America; GTS gauge network elsewhere Daily reports available from ~17,000 stations

Mingyue Chen and Pingping Xie

A blended precipforcing is used withthe heavier weights ofCFS/GDAS – high latsGauge – mid latsCMAP – tropics.

9

CFS Reanalysis Streams

1980 1985 1990 1995 2000 2005 2010

14 mo

12 mo

12 mo

12 mo

12 mo

Productionoverlap

All streams use the mean 2006-2007land states from operational GDASof each given start date as the land initial conditions.

10

• Overlapping between streams isessential.

• With at least 12-month overlapping,the discontinuity between streams isreduced.

• GR2, while executing one singlecontinuous stream, also showed anupward trend over the past two decades.

11

CFSR Soil Moisture Climatology

12

CFSR Soil Moisture Climatology

13

CONUS 2-meter soil moisture [%]SMC Total SMC Anomaly

CFSR – 6 streams GR2 – 1 stream

Trend? Natural or model driven?

14

Illinois 2-meter soil moisture [mm] Total

Anomaly

R(GR2,OBS)=0.48 R(NARR,OBS)=0.67 R(CFSR,OBS)=0.61

15

CONUS soil moistureMay climatology and anomaly

CFSR climatology

GR2 climatology

CFSR 1988 drought

GR2 1988 drought

CFSR 1993 flood

GR2 1993 flood

16

CONUS soil moistureMay climatology and anomaly

CFSR 1999

GR2 1999

CPC 90-day obs precip anomalyended 30Apr1999

CFSR soil moisture anomaly correspondswell with observed precip anomaly.

17

Land Surface Water Budget30-year mean annual cycle, 1980-2008

precip evap

runoff soil moisture

18

Summary• LIS/GLDAS as the land analysis of CFSR• Noah land surface model upgrades• A blended forcing to utilize observed precip to reduce the

impact of forecast model bias• Overlapping reduces the discontinuity between CFSR

streams.• Result shows reasonable soil moisture climatology and

anomaly.• Further analysis given in the companion two posters:

J. Meng et al., and R. Yang et al.• Reanalysis as initial conditions for Reforecast• Guidelines for future land surface model development• For CFSR data access at NCDC:

http://nomads.ncdc.noaa.gov/NOAAReanalysis/cfsrr