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1. THE CALIPSO MISSION : A Global 3D View of Aerosols and Clouds

Author

Winker, D. M., Pelon, J., Coakley, J. A., Ackerman, S. A., Charlson, R. J., Colarco, P. R., Flamant, P., Fu, Q., Hoff, R. M., Kittaka, C., Kubar, T. L., Le Treut, H., Mccormick, M. P., Mégie, G., Poole, L., Powell, K., Trepte, C., Vaughan, M. A., and Wielicki, B. A.

Published
2010

4. On the Nature and Extent of Optically Thin Marine low Clouds

Author

Leahy, L. V, Wood, R, Charlson, R. J, Hostetler, C. A, Rogers, R. R, Vaughan, M. A, and Winker, D. M

Subjects
Meteorology And Climatology
Abstract

Macrophysical properties of optically thin marine low clouds over the nonpolar oceans (60 deg S-60 deg N) are measured using 2 years of full-resolution nighttime data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Optically thin clouds, defined as the subset of marine low clouds that do not fully attenuate the lidar signal, comprise almost half of the low clouds over the marine domain. Regionally, the fraction of low clouds that are optically thin (f(sub thin,cld)) exhibits a strong inverse relationship with the low-cloud cover, with maxima in the tropical trades (f(sub thin,cld) greater than 0.8) and minima in regions of persistent marine stratocumulus and in midlatitudes (f(sub thin,cld) less than 0.3). Domain-wide, a power law fit describes the cloud length distribution, with exponent beta = 2.03 +/- 0.06 (+/-95% confidence interval). On average, the fraction of a cloud that is optically thin decreases from approximately 1 for clouds smaller than 2 km to less than 0.3 for clouds larger than 30 km. This relationship is found to be independent of region, so that geographical variations in the cloud length distribution explain three quarters of the variance in f(sub thin,cld). Comparing collocated trade cumulus observations from CALIOP and the airborne High Spectral Resolution Lidar reveals that clouds with lengths smaller than are resolvable with CALIOP contribute approximately half of the low clouds in the region sampled. A bounded cascade model is constructed to match the observations from the trades. The model shows that the observed optically thin cloud behavior is consistent with a power law scaling of cloud optical depth and suggests that most optically thin clouds only partially fill the CALIOP footprint.

Published
2012
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11. Reply

Author

Penner, J. E., Charlson, R. J., Hales, J. M., Laulainen, N. S., Leifer, R., Novakov, T., Ogren, J., Radke, L. F., Schwartz, S. E., and Travis, L.

Published
1994

18. Reply

Author

Charlson, R. J. and Pilat, M. J.

Published
1971

19. Reply

Author

Pueschel, R. F., Charlson, R. J., and Ahlquist, N. C.

Published
1971

22. Aerosols and Global Warming

Author

Kellogg, William W., Charlson, R. J., Schwartz, S. E., Hales, J. M., Cess, R. D., Coakley,, J. A., Hansen, J. E., and Hofmann, D. J.

Published
1992

26. Reconciling aerosol light extinction measurements from spaceborne lidar observations and in situ measurements in the Arctic.

Author

Tesche, M., Zieger, P., Rastak, N., Charlson, R. J., Glantz, P., Tunved, P., and Hansson, H.-C.

Subjects
ATMOSPHERIC aerosols, SPACE-based radar, LIGHT, LIDAR
Abstract

In this study we investigate to what degree it is possible to reconcile continuously recorded particle light extinction coefficients derived from dry in situ measurements at Zeppelin station (78.92o N, 11.85° E; 475 m above sea level), Ny-Ålesund, Svalbard, that are recalculated to ambient relative humidity, as well as simultaneous ambient observations with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. To our knowledge, this represents the first study that compares spaceborne lidar measurements to optical aerosol properties from short-term in situ observations (averaged over 5 h) on a case-by-case basis. Finding suitable comparison cases requires an elaborate screening and matching of the CALIOP data with respect to the location of Zeppelin station as well as the selection of temporal and spatial averaging intervals for both the ground-based and spaceborne observations. Reliable reconciliation of these data cannot be achieved with the closest-approach method, which is often used in matching CALIOP observations to those taken at ground sites. This is due to the transport pathways of the air parcels that were sampled. The use of trajectories allowed us to establish a connection between spaceborne and groundbased observations for 57 individual overpasses out of a total of 2018 that occurred in our region of interest around Svalbard (0 to 25° E, 75 to 82° N) in the considered year of 2008. Matches could only be established during winter and spring, since the low aerosol load during summer in connection with the strong solar background and the high occurrence rate of clouds strongly influences the performance and reliability of CALIOP observations. Extinction coefficients in the range of 2 to 130 Mm-1 at 532 nm were found for successful matches with a difference of a factor of 1.47 (median value for a range from 0.26 to 11.2) between the findings of in situ and spaceborne observations (the latter being generally larger than the former). The remaining difference is likely to be due to the natural variability in aerosol concentration and ambient relative humidity, an insufficient representation of aerosol particle growth, or a misclassification of aerosol type (i.e., choice of lidar ratio) in the CALIPSO retrieval. [ABSTRACT FROM AUTHOR]

Published
2014
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29. Laboratory Studies and Numerical Simulations of Cloud Droplet Formation under Realistic Supersaturation Conditions.

Author

Stratmann, F., Kiselev, A., Wurzler, S., Wendisch, M., Heintzenberg, J., Charlson, R. J., Diehl, K., Wex, H., and Schmidt, S.

Subjects
TROPOSPHERIC thermodynamics, ATMOSPHERIC water vapor, CLOUDS, ATMOSPHERIC research, NUMERICAL analysis, METEOROLOGY
Abstract

In this paper, a new device is introduced to study the formation and growth of cloud droplets under heal atmospheric supersaturations. The new device, called the Leipzig Aerosol Cloud Interaction Simulator (LACIS), is based on a laminar flow tube. It has been designed to reproduce the thermodynamic conditions of atmospheric clouds as realistically as possible. A series of experiments have been conducted that Dove the definition and stability of the flow field inside the LACIS as well as the stability and reproducibility of the generated droplet size distributions as a function of the applied thermodynamic conditions. Measured droplet size distributions are in good agreement with those determined by a newly developed Eulerian particle-droplet dynamical model. Further investigations will focus on the influences of latent beat release during vapor condensation on the tube walls and the development of a more suitable optical particle counter for droplet size determination. [ABSTRACT FROM AUTHOR]

Published
2004
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