The focus of my current work is marine boundary atmospheric layer (MABL) clouds, principally stratus and stratocumulus. The MABL couples ocean surface processes with clouds and convection over the eastern Pacific, including over the regions covered by a year-long deck of stratus/stratocumulus (i.e., the northeast Pacific off of the California and Mexican coasts and the southeast Pacific off of the South American coast). Over these regions, the MABL is directly affected by entrainment processes linked to cloud-top radiative and evaporative cooling, while the amount of clouds are closely connected to the structure of the MABL (e.g., Albrecht et al. 1995, Stevens et al. 2003).
The importance of the marine atmospheric boundary layer (MABL) and stratus/stratocumulus clouds in atmospheric and atmosphere-ocean coupled models has been widely recognized, particularly over the Southeastern Pacific (SEP). However, the simulation of these processes still has serious deficiencies even in the most recent model versions, as discussed in the VOCALS Modeling Plan (2006). As part of the overall VOCALS modeling efforts, we are integrating the in situ data from VOCALS and previous field experiments as well as satellite (CloudSat, CALIPSO, ICESat, MODIS) data to address these issues in order to document and understand the temporal and spatial variation of MABL height and clouds over the southeast Pacific and to evaluate and improve the treatment of MABL, cloud microphysics, and cloud fraction in CCSM3 and CFS03.
To this end, we have performed a satellite intercomparison of liquid water path (LWP), a multi-platform comparison of cloud properties with those simulated by CAM3.1, and a budget analysis of various contributions to the change in grid-volume average cloud condensate. For more information on this project, go to the UA-VOCALS web site.
Albrecht, B. A., M. P. Jensen, and W. J. Syrett, 1995: Marine boundary layer structures and fractional cloudiness. Journal of Geophysical Research, 100, 14 209-14 222.
Stevens, B., and 12 co-authors, 2003: On entrainment rates in nocturnal marine stratocumulus. Quarterly Journal of the Royal Meteorological Society, 129, 3469-3493.
VOCALS Scientific Working Group, 2006: VOCALS Modeling Plan. Available at http://www.eol.ucar.edu/projects/vocals/