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Predicting the Earth System Across Scales: Both Ways

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For 1991-1993 only one hurricane developed from AEWs, there were no July storms ... Simulate feedback between hurricanes and ocean/atmospheric circulations ... – PowerPoint PPT presentation

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Title: Predicting the Earth System Across Scales: Both Ways


1
Predicting the Earth System Across Scales
Both Ways
Greg Holland NCAR
Summary Rationale Approach and Current
Focus Improved Simulation of Tropical
Modes Requirements for Tropical Cyclone Response
to Climate Change
2
Rationale Regional Climate
  • Downscaling
  • Upscaling

3
Downscaling and Upscaling Atlantic Tropical
Cyclone Trends
Satellites
4
Upscaling Mean Rainfall
5
Upscaling and Downscaling Tropical Modes
Observed
CCSM
(Lin et al 2006)
All tropical modes are poorly handled by current
climate models. This impacts everything from
tropical cyclones to ENSO and interactions with
the extratropics.
6
The Opportunity
CCSM/CAM Community Models
WRF Community Model
7
Approach and Current Focus
  • Approach Nesting the NCAR Weather Research
    and Forecasting Model into CAM as a 2-way Nested
    Regional Climate Model (NRCM)
  • Stage 1 Downscaling over North America (done)
  • Stage 2 2-way atmospheric scale interactions in
    the tropics (current)
  • Stage 3 NRCM in CAM/CCSM, with coupled ocean
    model as a community facility (next).
  • Current Focus Tropical scale interactions
  • Importance of mesoscale organization of
    convection and its related surface exchanges and
    radiative influences for forcing tropical modes
  • Tropical mode forcing of tropical cyclone
    development and intensification.

8
Model Setup
Tropical Channel, 36 km, N/S boundaries 1-way
nested into NCEP Reanalysis with specified SST,
Kain-Fritsch Cu Parameterization, CAM radiation
and YSU boundary layer.
Precipitable Water (mm)
4 km nested domain inside 12 km and 36 km
domains, fully 2-way interactive, Dudia cloud
physics, CAM radiation and YSU boundary layer.
Wind Speed (m/s)
9
NRCM Experiments
  • CAM at T170 Resolution Jan 1, 1966 to Jan 1 2001
  • 36km Channel Model Jan 1, 1996 to Jan 1, 2001
  • 36km Channel high resolution SST's Jan 1,
    1999 to Jan 1, 2000
  •  
  • 36km Channel fluxes Jan 1, 1996 to Jan 1 1998
  • 36km Channel 12km Maritime domain Jan 1, 1996
    to Feb 12, 1998
  • 36km Channel 12/4km Maritime domains Jan 1,
    1997 to Jul 1, 1997

10
Precipitable Water 1997
11
Power Spectra
NCEP Analysis
12
MJO and Easterly Wave Simulation
13
July 22nd over eastern Indonesia
MJO wet phase
28 days
August 19th in eastern North Pacific
39 days
October 8th westerly wind burst
14
Easterly Wave Interactions with MJO
15
NRCM Tropical Cyclone Simulation Seasonal
Distribution 1996-1998
16
Annual Tropical Cyclone Statistics
Yellow are Observed Blue are Simulated. SWIO
Southwest Indian Ocean WAUS Western
Australia SWP
Southwest Pacific NIO North
Indian Ocean NWP Northwest Pacific
ENP Eastern North Pacific NAT North
Atlantic.
17
Tropical Cyclones and Climate Change
18
AEW Development
9-y Running Mean
19
Importance of AEW Development
gt85 of all Major Hurricanes develop from
Easterly Waves!!!
20
East/West Atlantic and Gulf SSTs
21
Global Surface Temperature Variability
Volcano
1970
Solar
Sulfate
There is no known natural forcing mechanism that
can explain the surface temperature increases
since 1960 (Meehl et al 2004, 2006) Notice the
warm 1940-50 period in the natural cycle
Ozone
22
So what is happening?
  • Compare the record 2005 season with a mean of
    1991-1993
  • 2005 27 Storms, 12 hurricanes, 5 cat 4-5
  • 1991-1993 22 storms (total), 12 hurricanes, 2
    cat 4-5
  • 2995 30 of all AEWs became named storms
    (normally 10)
  • AEWs produced 10 of the 14 hurricanes in 2005,
    all category 3-5 hurricanes, all tropical
    cyclones in July and August, and 8 of the 11
    tropical cyclones in September and October. Two
    AEWs also generated two tropical cyclones each, a
    rare event that last occurred in 1988
  • For 1991-1993 only one hurricane developed from
    AEWs, there were no July storms and only one in
    October.

23
2005 vs 1991-1993
24
NAT SST-Hurricane Relationships
Max SST
North Atlantic oceanic and atmospheric response
to global warming.
25
Vorticity Changes du/dxlt0
July 2005
26
Assessing Potential Climate Change Impact on
Tropical Cyclones Requirements
  • Resolve hurricane structure
  • Simulate tropical atmospheric response to oceanic
    heat changes
  • Simulate tropical modes accurately
  • Simulate feedback between hurricanes and
    ocean/atmospheric circulations

Coupling CCSM/CAM with WRF and a GOM/ROM enables
this
27
Summary
  • The weather and climate scales are part of a
    continuum of action across scales
  • We have the tools in CAM/CCSM and WRF to open up
    new frontiers in understanding and predicting
    these 2-way interactions
  • The Petascale Computing Facility provides the
    capacity

So Lets Do It
Thank You
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