drilling into the cloud feedback - nasa · 2012. 5. 2. · drilling into the cloud feedback c....
TRANSCRIPT
Drilling into the cloud feedback
C. Zhou, A. E. Dessler, P. YangDepartment of Atmospheric Sciences
Texas A&M University
Wednesday, May 2, 2012
CERES top-of-atmosphere (TOA) net fluxSSF, 1-deg monthly avg., Ed. 2.5
longwave + shortwave
all fluxes in this analysis are downward positivecover period 2/2000-12/2010
2
1.5
1.0
0.5
0.0
-0.5
-1.0
∆Rall
-sky
(W/m
2 )
201020082006200420022000Year
(a)
Wednesday, May 2, 2012
3
1.5
1.0
0.5
0.0
-0.5
-1.0
∆Rall
-sky
(W/m
2 )
201020082006200420022000Year
(a)
∆Rall-sky = ∆RT +∆Rq +∆Ralbedo +∆Rcloud+∆F
∆Rcloud = ∆CRF + adjustments
Wednesday, May 2, 2012
3
1.5
1.0
0.5
0.0
-0.5
-1.0
∆Rall
-sky
(W/m
2 )
201020082006200420022000Year
(a)
∆Rall-sky = ∆RT +∆Rq +∆Ralbedo +∆Rcloud+∆F
∆Rcloud = ∆CRF + adjustments
Wednesday, May 2, 2012
4
Wednesday, May 2, 2012
5
Wednesday, May 2, 2012
5
CRF = ∆Rclear-sky - ∆Rall-sky
Wednesday, May 2, 2012
5
CRF = ∆Rclear-sky - ∆Rall-sky
Reanalysis
Wednesday, May 2, 2012
5
CRF = ∆Rclear-sky - ∆Rall-sky
Reanalysis CERES
Wednesday, May 2, 2012
∆Rcl
oud
∆Ts
Regress CRF vs. surface temperature
Wednesday, May 2, 2012
∆Rcl
oud
∆Ts
Regress CRF vs. surface temperature
Slope = feedback
Wednesday, May 2, 2012
7
-0.4-0.3-0.2-0.10.00.10.2
∆Ts (
K)
201020082006200420022000Year
Wednesday, May 2, 2012
7
-0.4-0.3-0.2-0.10.00.10.2
∆Ts (
K)
201020082006200420022000Year
El Nino
La Nina
Wednesday, May 2, 2012
∆Ts
8
∆Rcl
oud
Dessler, Science, 2010
0.49±0.69 W/m2/K0.58±0.70 W/m2/Kcloud feedback =
Wednesday, May 2, 2012
9
Observations
Control ensemble = avg. of 13 models
Each point is the regression slope ofΔRcloud(lat,lon) vs. global avg. ΔTs
It is the local contribution to the global feedback
Wednesday, May 2, 2012
10
obs.
control
Wednesday, May 2, 2012
11
MODIS data (%/K)
Optical depth45°N-45°STerra MODIS
Calculations byChen Zhou
Wednesday, May 2, 2012
12
X
• Kernels calculated by Mark Zelinka
Wednesday, May 2, 2012
13
Cloud feedback as afunction of latitudefrom the CERES data
W/m2/K
Wednesday, May 2, 2012
14
Blue: CERESGreen: MODIS
W/m2/K
Wednesday, May 2, 2012
15
Wednesday, May 2, 2012
16High: P < 440 hPa; Low: P > 680 hPa
Wednesday, May 2, 2012
17
breakdown into cloudheight (low: P > 680 hPa, high: P < 310 hPa)
Wednesday, May 2, 2012
18
longwave shortwave
long + shortwave
Wednesday, May 2, 2012
Conclusions• global average cloud feedback (over the last 10 years)
is likely positive• models show a difference in the net cloud feedback
pattern• good agreement between the adjusted CRF method
and the cloud kernel method• short and longwave cloud feedbacks are individually
dominated by high clouds --- but they cancel almost completely in the net
• because mid- and low-level clouds do not have the same cancellation, they are important in the net feedback
19
Wednesday, May 2, 2012
20
Wednesday, May 2, 2012
21
W/m
2 /K
Wednesday, May 2, 2012
22
Wednesday, May 2, 2012