a sharper view of fuzzy objects: warm clouds and their role in the climate system as seen by...
TRANSCRIPT
![Page 1: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/1.jpg)
A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System
as seen by Satellite
Ralf BennartzUniversity of Wisconsin – Madison
![Page 2: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/2.jpg)
Outline
• What do we want to know?
• Cloud microphysical parameters
• Cloud fraction and albedo
• Conclusions and outlook
![Page 3: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/3.jpg)
Clouds are the single-most important factor modulating climate sensitivity…..
… and we know very little about forcings and feedbacks
IPCC 2007
![Page 4: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/4.jpg)
IPCC 2007
21 climate models- one scenario
![Page 5: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/5.jpg)
How can observations help narrow down these uncertainties?
![Page 6: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/6.jpg)
What do we need to know?
• Cloud droplet number concentration (N)
• Liquid water path (LWP)
• Drizzle/rain? Rain water path (RWP)
• Cloud fraction
• Albedo
![Page 7: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/7.jpg)
(Sub) adiabatic stratiform clouds
LWC
![Page 8: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/8.jpg)
• LWP from VIS/NIR: Factor f depends on stratification of cloud (e.g. f=5/9 for adiabatic, f=2/3 for vertically uniform)
• N for an adiabatic cloud related to optical depth and LWP. C depends weakly on temperature and width of droplet spectrum
Basic physical relations
![Page 9: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/9.jpg)
• LWP from VIS/NIR: Factor f depends on stratification of cloud (e.g. f=5/9 for adiabatic, f=2/3 for vertically uniform)
• N for an adiabatic cloud related to optical depth and LWP. C depends weakly on temperature and width of droplet spectrum
• MW: Very direct measurement. Mass absorption coefficient depends slightly on temperature, σr depends on rain water content too.
Basic physical relations
![Page 10: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/10.jpg)
Basic physical relations
Bennartz et al. (2010)
![Page 11: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/11.jpg)
Basic physical relations
Bennartz et al. (2010)
![Page 12: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/12.jpg)
Three input variables (τVIS reff τMW)
Three output variables (N,LWP,RWP)
Basic physical relations
![Page 13: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/13.jpg)
Three input variables (τVIS reff τMW)
Three output variables (N,LWP,RWP)
Auxiliary data, assumptions:
• Cloud top height• Cloud top temperature• Drizzle/rain particle size distribution• Width of cloud droplet spectrum
Basic physical relations
![Page 14: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/14.jpg)
• Direct physical relationship between MW/VNIR optical properties and cloud physical properties.
• Errors and uncertainties due to input and auxiliary parameters can be specified and dependencies can be explicitly spelled out.
• Validity of assumptions can be assessed from observations.
• No unknown unknowns (though a lot of known unknowns).
Basic physical relations
![Page 15: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/15.jpg)
Bennartz et al. (2010), Bennartz (2007), Rausch et al. (2010)
Products
![Page 16: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/16.jpg)
Cloud droplet number concentration
![Page 17: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/17.jpg)
Cloud droplet number concentration
![Page 18: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/18.jpg)
Cloud droplet number concentration
Bennartz et al. (2011)
![Page 19: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/19.jpg)
Cloud droplet number concentration
Bennartz et al. (2011)
![Page 20: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/20.jpg)
Application example: Constraining cloud-aerosol interaction processes in GCMs
Storelvmo, Lohmann, Bennartz (2009)
Differences in cloud droplet activation account for about 65 % (1.3 W/m2) of the total spread in shortwave forcing (2 W/m2) in IPCC AR4 models
![Page 21: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/21.jpg)
• Deviations from adiabaticity valid ‘targets’ can be identified by checking multi-spectral agreement of reff with adiabatic assumption.
Open issues & proposed solutions
![Page 22: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/22.jpg)
Effective Radius
![Page 23: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/23.jpg)
• Deviations from adiabaticity valid ‘targets’ can be identified by checking multi-spectral agreement of reff with adiabatic assumption.
Open issues & proposed solutions
![Page 24: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/24.jpg)
• Deviations from adiabaticity valid ‘targets’ can be identified by checking multi-spectral agreement of reff with adiabatic assumption.
• Physical explanation for differences in reff still outstanding: partly cloudy pixels, subscale variability, rain, 3D…. Probably all of them to some extend
Open issues & proposed solutions
![Page 25: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/25.jpg)
Validating models: LWP observations against iRAM
Lauer et al. (2009)
![Page 26: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/26.jpg)
Special Sensor Microwave/Imager
![Page 27: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/27.jpg)
Liquid Water Path [kg/m2]
Local Time [hours]
![Page 28: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/28.jpg)
Liquid Water Path [kg/m2]
Local Time [hours]
![Page 29: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/29.jpg)
Liquid Water Path [kg/m2]
Local Time [hours]
![Page 30: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/30.jpg)
Liquid Water Path [kg/m2]
Local Time [hours]
![Page 31: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/31.jpg)
Liquid Water Path [kg/m2]
Local Time [hours]
![Page 32: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/32.jpg)
Conclusions
• Satellite observations provide a wealth of information about cloud microphysical and radiative properties.
• Simple physically-based cloud models provide an excellent framework to interpret satellite observations and brigde gap between observations and GCMs
• Caveats, uncertainties, and the limits of our current understanding need to be conveyed.
• Working closely with GCM/RCM community.
![Page 33: A Sharper View of Fuzzy Objects: Warm Clouds and their Role in the Climate System as seen by Satellite Ralf Bennartz University of Wisconsin – Madison](https://reader036.vdocuments.mx/reader036/viewer/2022070414/5697c0111a28abf838ccb50e/html5/thumbnails/33.jpg)
Acknowledgements
Collaborations: A. Lauer (U Hawaii), T. Storelvmo (Yale), U. Lohmann (ETH), J. Rausch (UW-AOS), L. Borg, (UW-AOS), A. Heidinger, (NOAA), M. Foster (CIMSS), R. Leung (PNNL), J. Fan (PNNL), C. O’Dell (CSU), R. Wood (UW)
Funding: NASA MODIS Science Team, NOAA/Joint Center for Satellite Data Assimilation, DOE Regional Climate Modeling