SooHyun Yoo

1

• Impact of Land Surface Model on the Asian Monsoon
  Climate
• in the NCEP Climate Forecasting System

Soo-Hyun Yoo NCEP Climate Prediction Center Jae
Schemm, Song Yang, Rongqian Yang, and Kenneth
Mitchell Climate Prediction Center
Environmental Modeling Center January 4, 2008
2

• Outline

• Climatological features
• Precip, 2m-T, SST, 850-mb 200-mb Wind
• Correlation scores
• Precip 2m-T
• Seasonal-interannual variability of the Asian
  monsoon

3

• Description of CFS LSM related experiments

• Impact on CFS of
• new land model (Noah LSM vs OSU LSM)
• new land initial conditions (GLDAS vs GR2)
• C) new version of CFS (Experimental CFS vs
  Operational CFS)

Note GR2 denotes NCEP/DOE Global Reanalysis 2
GLDAS denotes Global Land Data
Assimilation System
4

• Experimental CFS Land Model Upgrade (Noah vs OSU)

• Noah LSM (New)
• 4 soil layers (10, 30, 60, 200 cm)
• Frozen soil physics included
• Surface fluxes weighted by snow cover fraction
• Improved seasonal cycle of vegetation cover
• Spatially varying root depth
• Runoff and infiltration account for sub-grid
  variability in precipitation soil moisture
• Improved soil snow thermal conductivity
• Higher canopy resistance
• Other

• OSU LSM (Old)
• 2 soil layers (10, 190 cm)
• No frozen soil physics
• 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

Modified from R. Yangs presentation
5

• Experimental CFS Land Initial Data Upgrade
  (GLDAS vs GR2)

• GR2
• Coupled atmosphere/land assimilation system
  wherein land component is driven by model
  predicted precipitation
• Applies the OSU LSM
• Nudges soil moisture based on differences between
  model and CPC CMAP precipitation

• GLDAS
• Uncoupled land simulation system driven by
  observed precipitation analyses (CPC CMAP
  analyses)
• Executed using same grid, land mask, terrain
  field and Noah LSM as GFS in experimental CFS
• Non-precipitation land forcing is from GR2
• Executed retrospectively from 1979-2006 (after
  spin-up)

Modified from R. Yangs presentation
6

• Data

• Precipitation CMAP data (144x72 )
• TMP 2m GHCN/CAMS Global T2m ( 144x73 )
• SST OISST ( 1x1 )
• 850-mb 200-mb Wind NCEP/DOE Reanalysis 2

7

• Climatological Features

8
Climatological Features Precipitation
9
Climatological Features 2m Temperature
10
Climatological Features SST
11
Climatological Features 850-mb Wind
12
Climatological Features 200-mb Wind
A
13

• Correlation Scores

14
Correlation Scores Precipitation
15
Correlation Scores Precipitation
16
Correlation Scores 2m Temperature
17
Correlation Scores 2m Temperature
18
Interannual Variability and Correlation Scores of
Area Averaged Precipitation over Asia
19
Interannual Variability and Correlation Scores of
Area Averaged 2m Temperature over Asia
20
(No Transcript)
21

• Monsoon Variability

22
Interannual Variability of SST Indices
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
Interannual Variability of Monsoon Indices
28
Monsoon Onset and Time Evolution
SESM
IM
29
Aug-Sep
30
Aug-Sep
31

• Summary

• CFS simulations change more noticeably between
  different land models than among different land
  initial conditions.
• The summer climatologies over Asia are more
  reasonably simulated in CFS Noah LSM compatible
  GLDAS initial conditions than other model
  configurations.
• Correlation scores for precipitaion and 2-meter
  temperature are the best over subtropical Asia
  in configuration CFS Noah_GLDAS.

32

• Thanks!

33

• II. Impact of Horizontal Model Resolution

34

• Description of CFS related experiments

• Impact on CFS of different horizontal resolution
• (T62, T126 vs T382)

35
Climatological Features SST
36
Climatological Features Precipitation
37
Climatological Features 2m Temperature
38
Temporal Correlation Precipitation
39
Temporal Correlation 2m Temperature
40
Correlation Scores of Precip over Indo SE Asia
Monsoon region
41
Correlation Scores of 2m Temperature over Indo
SE Asia Monsoon region
42
IM
SEAM
43

• Summary II

• A single run for the ICs of 15 May is taken from
  new CFS hindcast runs with GFS07 for different
  horizontal resolutions, T62, T126, and T382. The
  experiments are integrated up to October over a
  period from 1981-2006.
• The model climatologies for precipitation are
  more reasonably simulated for summer and fall
  over the Asian monsoon region in CFS T382.
• The onset and intensity of the Indian monsoon is
  substantially improved in CFS T382.
• CFS has moderate correlation skills of 2m
  temperature for summer over the Asian monsoon
  region, which is noticeably enhanced in CFS T382.