Land Analysis in the NOAA CFS Reanalysis Michael Ek, Ken Mitchell, Jesse Meng Helin Wei, Rongqian Yang, and George Gayno 1
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 2
CFS Reanalysis Execution (24-hr span) : Note daily GLDAS Atmos. Analysis 0Z GSI 6Z GSI 12Z GSI 18Z GSI 0Z GSI 0Z GODAS 6Z GODAS 12Z GODAS 18Z GODAS 0Z GODAS Ocean Analysis 0Z GLDAS 6Z GLDAS 12Z GLDAS 18Z GLDAS 0Z GLDAS Land Analysis Time 3
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GFS and CFS: Land Model Upgrade Noah LSM (new) versus OSU LSM (old): Noah LSM (vegetation, snow, ice) OSU LSM 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 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-range Global Forecast System (GFS) in late May 2005 5
Land Information System Land Surface Characteristics Topography Land Cover Soil Precipitation Forcing Non-precip Meteorological Forcing Land Variables Soil Moisture Soil Temperature Snow Noah LSM Christa Peters-Lidard et al., NASA/GSFC/HSB CFSR land analysis Soil Moisture Soil Temperature Snow CFSR surface file gdas1.t00z.sfcanl 6
Motivation for Using Observed Precipitation in CFSR GDAS high bias in tropical precip compared to CMAP analysis 10 July 09 Aug 2007 Example Difference Plot GDAS yields high precip bias in tropics. 7
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 A blended precip forcing is used with the heavier weights of CFS/GDAS high lats Gauge mid lats CMAP tropics. Mingyue Chen and Pingping Xie 8
CFS Reanalysis Streams overlap All streams use the mean 2006-2007 land states from operational GDAS of each given start date as the land initial conditions. 12 mo Production 12 mo 12 mo 12 mo 14 mo 1980 1985 1990 1995 2000 2005 2010 9
Overlapping between streams is essential. With at least 12-month overlapping, the discontinuity between streams is reduced. GR2, while executing one single continuous stream, also showed an upward trend over the past two decades. 10
CFSR Soil Moisture Climatology 11
CFSR Soil Moisture Climatology 12
CONUS 2-meter soil moisture [%] SMC Total SMC Anomaly CFSR 6 streams GR2 1 stream Trend? Natural or model driven? 13
Illinois 2-meter soil moisture [mm] Total Anomaly R(GR2,OBS)=0.48 R(NARR,OBS)=0.67 R(CFSR,OBS)=0.61 14
CONUS soil moisture May climatology and anomaly CFSR climatology CFSR 1988 drought CFSR 1993 flood GR2 climatology GR2 1988 drought GR2 1993 flood 15
CONUS soil moisture May climatology and anomaly CPC 90-day obs precip anomaly ended 30Apr1999 CFSR 1999 GR2 1999 CFSR soil moisture anomaly corresponds well with observed precip anomaly. 16
Land Surface Water Budget 30-year mean annual cycle, 1980-2008 precip evap runoff soil moisture 17
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 18