1. Comparing radiative kernels in the context of feedbacks and forcings on the hydrological cycle
Ryan Kramer and Brian Soden
University of Miami/RSMAS
PDRMIP Meeting, May 11, 2017

2. Earth’s Energy Budget
L’Ecuyer et al. 2015

3. Radiative Kernel-Regression Technique
Feedback
Rapid Adjustment

4. Radiative Kernels
W/m2/K/100hPa

5. Soden et al. 2008 TOA Kernel Comparison

6. Differing Water Vapor Radiative Kernels
Flaschner et al (ECHAM6)
Previdi 2010 (ECHAM5)
λWV,LW = W/m2/K
λWV,LW = 0.29 W/m2/K

7. Atmospheric Feedbacks and Adjustments
Large inter-kernel differences (colors) in:
Planck and WV feedback
Cloud Adjustments
Total Stratospheric Adjustments
Model
Source
GFDL
Soden et al. 2008
CAWCR
(R. Colman)
ECHAM5
Previdi 2010
ECHAM6
Block and Mauritsen 2013
NCAR CESM1.1
A. Pendergrass
HadGEM2
C. Smith
ECMWF
G. Myhre

8. Zonal-mean Atmospheric Radiative Kernel Differences
W/m2/K/100hPa

9. Zonal-mean Atmospheric Radiative Kernel Differences

10. Downwelling component to Surface KTs

11. Downwelling component to Surface KTs

12. Impacts of Resolution
Four lowest model levels of surface flux air temperature kernel.

13. Impacts of Resolution
Clear-Sky Atmospheric flux air temperature radiative kernels:
Original radiative kernel
(solid line)
Fu-Liou RTM + CMIP5 base climate on original kernel model levels
(Dashed line)

14. Ensemble of CMIP5 Base Climates
W/m2/K/thickness

15. CloudSat Radiative Kernels
Observational Kernels from 2B-FLXHR-LIDAR:
Input
Source
Cloud Properties
CloudSat, CALIPSO
Temperature, Humidity
ECMWF Reanalysis
Surface Albedo
MODIS, AMSR-E
Aerosol Properties
CALIPSO
TOA Response
W/m2/K/100hPa

16. Conclusions
Atmospheric radiative kernels large in magnitude and spread near or at the surface.
Differing radiative transfer models and different base climates both contribute to radiative kernel differences between modeling sources
Downwelling issue in surface component of KT
Impacts of vertical resolution

17. What can cause Radiative Kernel Differences?
1. Radiative transfer model
differences
2. Model base climate
biases
DeAngelis et al. 2015

18. Same Base Climate, Different RTM
Sun–Edwards–Slingo

19. Same Base Climate, Different RTM
SFC KTs nearly identical

20. Feedback-Forcing FrameworkSW s
Feedbacks
Temperature
Water Vapor
Surface Albedo
Clouds
Rapid Adjustments
Temperature
Water Vapor
Surface Albedo
Clouds
Rapid adjustments: An increase in CO2, for example, will instantaneously change radiative heating in the atmosphere, which can lead to tropospheric warming, changes in stratification, convection etc, which will induce a radiative response that can be felt at the TOA or Surface. LW
Fig. adapted from Sherwood et al. 2015