vertical resolution in the next generation cam & waccm
TRANSCRIPT
Vertical resolution in the next generation CAM &
WACCMJadwiga (Yaga) Richter & Brian Medeiros
CGD/NCAR
Your Input is needed•Vertical resolution & model top are critical issues to settle
for CAM7/WACCM7
•Yaga Richter & Brian Medeiros will lead revision of
CAM/WACCM’s grid
• Few things to think about….
CAM7/WACCM7
• ENSO, MJO• Mean state (U/T/Precip) • ITCZ• Aerosols/Clouds• Paelo
Climate Studies:
Middle/upper atmospheric dynamics/chemistry:
• Low U/T biases• QBO, SSWs• Water vapor,
ozone transport• Aerosols
Initialized Prediction:
• ENSO, QBO, MJO • Stratospheric factors• External forcings
(volcanos etc)CAM7
WACCM7
Historical Perspective
(Richter et al. 2014a)
1983: CCM0: 4.4 x 7.5o 9L
1990: CCM1: 4.4 x 7.5o 12L
1994: CCM2: 2.8 x 2.8o 18L
2006: CAM3: 2.8 x 2.8o 26L (66L)
2013: CAM4: 0.95x1.25o 26L (66L)
2015: CAM5: 0.95x1.25o 30L (70L)
2018: CAM6: 0.95x1.25o 32L (70L)
WACCM
Boundary Layer (very bottom):• Very bottom layer should be 20 m (midpoint at 10 m) for adequate exchanges
between ocean and atmosphere • Want to resolve the depth of the stable BL (up to 200 m)
Where we are now:
Δz1= 110m Δz2= 132m
700 hPa
Where we would like to go:Δz1= 20m
+ levels at 40, 65, 90, 120, 160, 210m~7
Boundary Layer (200 m – 3 km):
ATEX, Stevens et al. 2001ASTEX, Chung et al. 2012 BOMEX, Xue & Feingold. 2006BOMEX, Siebesma et al. 2003
500m300m
250m 500m
Large-Eddy Simulations
• Studies suggest Δz ≤ 200m required to capture the effects of turbulence on clouds
Lenderink & Holtslag (2000), van Meijgaard & van Ulden (1998)
• Desired resolution of 100 – 150 m up to 700 hPa
Boundary Layer (200 m – 3 km):Where we are now:
Δz= 150 – 600 m
700 hPa
Ideal: Δz ~ 100 - 150m
+ levels at 20, 40, 65, 90, 120, 160, 210 m7
+ ~ 18 levels between 300–3000 m
CMIP5 Models
Total levels (levels below 700hPa)
Free troposphere/stratosphere:(For Quasi-geostrophic flows;Lindzen & Fox-Rabinovitz 1989, Boville 1991)
Current Δz 20o 45o 65o
Troposphere 1.2 km 0.5 km 1 km 1.3 km
Stratosphere 1.5 km 0.23 km 0.5 km 0.6 km
Free troposphere/stratosphere:Where we are now:
Δz ~ 1200 m - 1800 m in Free troposphere and lower stratosphere
CAM6
WACCM6
High vertical resolution CAMIn 2013: Doubled vertical resolution: 60LCAM
• Cut-down near-tropopause T biases by 2K• Improved Kelvin & Mixed Rossby-Gravity
waves• First internally generated QBO in CAM
(Richter et al. 2014a)
High vertical resolution
Richter et al. 2014a, JGR
30L60L 60L - 30L
MR-GWs
Kelvin WavesKiladis et al. 2009
High vertical resolution CAM
Richter et al. 2014b, JGR
2oS to 2oN U
60L+GW
30L
OBS
• QBO has stronger effect on
MJO than ENSO in boreal
winter (Son et al. 2017)
• MJO amplitude stronger
during easterly QBO
(Yoo and Son 2016)
Why care about QBO?
110L WACCM QBO & RG WavesEP Flux Div (shading)
Descending QBO W
Coherance2 Amp at k=8
Phase linesNo coherence with lower levels -> in situ generation of RG waves
Short vertical wavelengths (needing high vertical resolution)Garcia and Richter (2018, in prep)
Desired for CAM7/WACCM7
7 levels between 0 and 200 m
~ 70 - 72 levels
+ ~ 40 levels mideal ∆z ~ 500 - 700 m
+ ~ 50 - 60 levels mideal ∆z ~ 500 - 700 m
~ 5 – 7 levelsnear model top
~ 5 – 7 levelsnear model top
+ 40 – 50 levels
120 - 140 levels total
18 levels between 300–3000 m
+ ~ 50 - 60 levels mideal ∆z ~ 500 - 700 m
+ 25– 35 levels
~ 5 – 7 levelsnear model top
105 – 125 levels total
CAM7/WACCM7
CAM7+
WACCM7Option II
CAM7
HVR(~140L)HVR(~70 - 120L)LVR (32L)
CAM7
WACCM7Option I
HVR(~140L)LVR (32L)
WACCM7Option III
HVR(~140L)
Summary• Vertical resolution & model top are critical issues to settle
for CAM7/WACCM7
• YOUR INPUT IS NEEDED
• Yaga Richter ([email protected]) & Brian Medeiros
([email protected]) will lead revision of CAM/WACCM’s grid
• 2 Telecons between March 1 – May 30 to arrive at a prototype grid(s)
to be presented in the June CESM meeting
• Email your opinion and/or willingness to participate in further
discussions