Science and strategy on WP7 - Numerical weather and climate prediction modeling system to link observations with precipitation forecasts over the plateau and surrounding areas -

1
Science and strategy on WP7- Numerical weather
and climate prediction modeling system to link
observations with precipitation forecasts over
the plateau and surrounding areas -
2009.06 PM1 meeting Milano

• Kenichi UENO
• (Univ. Tsukuba, Japan)
• Xueshun SHEN
• (CAMS, China)

2
Objectives of WP7

• 1, Detailed analysis of the relationship between
  plateau land surface processes, monsoon onset and
  intense precipitations with a coupled
  land-atmosphere model
• ? UNITSU conduct the process studies, raise
  the hypothesis, and handle the candidates (cases)
  to CAMS for further forecast studies. Special
  focuses are interactions between meso- and
  synoptic-scale disturbances under the function of
  TP.
• 2, Improve lead time in the forecasts of intense
  precipitations
• ? CAMSs task

3
Seasonal march and targets
gtgt Preparing datasets and preliminarily
analysis gtgt Waiting the data from other WPs gtgt
Todayss topics.

1. Interactions of shallow/patchy snow cover and
   atmosphere during non-monsoon season for maturing
   of monsoon onset.
2. Land-surface condition and monsoon
   onset/variability over the TP during summer.
3. Function of TP to severe/extreme weather in the
   surrounding areas.

4
Example of extracted MCSs on METEOSAT-IR data
(below) and comparison with TRMM-PR data (right).
1330LT, Jul. 4, 1998
40N
14LT, Jul. 4, 1998
35N
30N
40N
29LT, Jul. 18, 1998
35N
30N
2845LT, Jul. 18, 1998
40N
20LT, Aug. 6, 1998
35N
1956LT, Aug. 6, 1998
30N
70E
100E
75E
80E
85E
90E
95E
5
TPx
(June 18)
Convective activities with intra-seasonal
variability propagated from the west.
They sometimes propagate out from the TP to the
south-east.
June 20-22
June 30-Jul 4
June 30-Jul 4
Jul 12-16
Jul 12-16
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Occurrences during nighttime
Case A June 22 12Z 23 06Z
Traveling mid-latitudes trough
Case B June 30 12Z July 1 6Z
Unique cloud zones passing over TP
Case C July 15 06Z 24Z
7
WRF Ver.3 Interacting
METEOSAT-IR
8
WRF V2
WRF V3 no interaction
WRF V3 with interaction
9
Dry air intrusion by the trough to maintain the
MCS
Low-level monsoon flow for convective instability
10
June 30 0Z-23Z, 2008 hourly simulation by WRF
(U,V) component
Equivalent Potential temperature
With basin
Without basin
(W component)
(W component)
WRF Ver. 3 with 4 km resolution demonstrated that
Sichuan Basin has a function to intrude northerly
dry flow associated with a trough at the bottom
which prevent local circulation and MCS
propagation from the TP.
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Other two cases
Case A OK A-
Case C not so OK B
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Short summary by Ueno

• Occurrence of MCSs associate with traveling
  synoptic scale trough (mid-latitude baroclinic
  instability/vortex)
• Monsoon flow from south provides convective
  instability condition.
• Dry air intrusion into the Shichan basin prevent
  the convections propagating from the TP but
  sudden onset of MCS.
• Function of middle level westelies in relation
  to plateau surface condition needs to be
  investigate to determine the environment of lee
  cyclogenesis.
• Accuracy of predicting mid-latitude system
  affected by the TP would also affect the
  predictions of MCS in the southeast.

13
WP-7 activities by CAMS modeling group during
past months

1. Rre-run of GRAPES_Meso for 2008, and verification
   of rainfall forecast over Tibet by GRAPES_Meso
2. Case study investigation of effect of different
   complexity LSM on convective initiation
   influence of land surface on PBL development
   convection
3. Systematic evaluation of effects of LSM on daily
   rainfall forecast for a successive heavy rainfall
   period
4. Preliminary study on the frictional effect of
   subgrid-scale topography in numerical model
5. Introduction of subgrid-scale horizontal
   diffusion with flux limiting over steep
   topography in GRAPES_Meso.

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GRAPES_Meso

• Physics
• Land surface RUC, NOAH
• Microphysics WSM, CAMS
• Convection KF, BM, SAS
• PBL YSU, modified MRF
• Diagnostic cloud
• ECMWF radiation package
• Effects of surface slope on surface radiation
• Dynamics
• Fully compressible non-hydrostatic equation
• Two-time level SISL time-stepping method
• PRM scalar advection
• Arakawa-C grid terrain-following Z coordinate
• GRAPES-3DVAR analysis

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(1) Evaluation of GRAPES_Meso on daily rainfall
forecast over Tibet
24-hr fcst
22.34N-34.55N 87E-100E
Area-averaged rainfall over Tibet
Sep.30/08
Apr.1/08
48-hr fcst
16
Threat Score of 24?36?48-hr rainfall forecast
over Tibet
April
WS south-western region of CN Whole All China
L M H
L M H
L M H
June
48hr
24hr
36hr
May
L M H
L M H
L M H
L M H
L M H
L M H
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(2) Effect of different complexity LSM on
convective initiation
2
1
Exp. Name LSM Initial Soil Condition
Noah Noah GLDAS
Slab Slab GLDAS
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Slab
Noah
(a)
Obs.

6-hr fcst
(d)
(a)??24?????, (b) Noah ???6????, (c) Slab
???6????, (d) Noah ???12????, (e) Slab
???12????? ??mm?
12hr fcst

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Latent heat flx
Sensible heat flx
CAPE CIN
PBL height

Time
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(3) Systematic evaluation of effects of LSM on
daily rainfall forecast

July 1-9, 2007
??????16km????2007?7?1?7?9?9???? 24??????????(a)
Noah, (b) Slab, (c) ?????mm
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Averaged Threat Score of 24hr rainfall forecast
for period of Jul.1-9,2007
16km
6km
2km
Sophisticated LSM has marginal advantage on
rainfall fcst
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Plan

• Successive 24-hour forecast experiments for at
  least 2 months in dry and rainy seasons (winter
  and summer) under the different land surface
  configurations or initial values (climatic state,
  GLDAS or other land surface analysis)
• Continuous work systematic evaluation of land
  surface effects on daily rainfall forecast in
  Tibet and process study.