Greg McFarquhar                                                               University of Illinois


The pilot of the ER-2 arrives back in San Jose after an overnight flight over Hurricane Emily. In addition to the NASA ER-2, the NOAA P-3 aircraft collected noteworthy data out of San Jose. They flew missions tracking the evolution of waves into tropical depressions. In between hurricane missions, the U of Illinois team found time to explore the jungles of Costa Rica, including some heavily forested regions.
TCSP: One of the key areas of tropical meteorology that remains elusive to both understanding and prediction is the genesis and intensification of tropical cyclones. With this motivation in mind, the Tropical Cloud Systems and Processes (TCSP) study was based out of San Jose, Costa Rica between June and July 2005 using the NASA ER-2 high altitude aircraft equipped with a number of instruments for remotely sensing the properties of hurricanes. The key questions addressed by TCSP included the following: 1) what processes govern tropical cyclogenesis in the eastern North Pacific and the Caribbean (intensification of easterly waves into depressions, mesoscale generation of cyclonic vorticity, or some combination of both)? 2) what dynamical and thermodynamic processes involving both the atmosphere and upper ocean contribute to rapid intensification of tropical cyclones (including the frequent occurrence of convective bursts during the development stage and the role of vertical wind shear)?; and 3) how does the low-level vortex of a tropical cyclone become established (e.g., descent of midlevel mesoscale vortices, the generation of convective-scale vortical hot towers (VHTs), and the horizontal merger of vortices.
Uof Illinois Role and Interests:The work of the Illinois group was sponsored by the NASA Hurricane Sciences Team. Prof. McFarquhar and Dr. Matt Gilmore each spent part of the project in Costa Rica, working on flight planning and data quality control. Prof. McFarquhar worked with other TCSP investigators as lead flight scientist for the ER-2 overflight of Hurricane Emily, the first flight of the NASA ER-2 over a category 5 hurricane! After TCSP, the analysis of the Illinois group has concentrated on using the remote sensing data to evaluate the results of hurricane simulations conducted using the Weather Research and Forecasting (WRF) model so that the mechanisms by which cloud and aerosol microphysical processes impact the four-dimensional distribution of latent heating, distributions of updrafts and downdrafts and the resulting intensity changes.

Publications arising from TCSP:

Kakar, R., F. Marks Jr., G. McFarquhar and R. Hood, 2006: Preface. J. Atmos. Sci., 63, 3-4.

McFarquhar, G.M., H. Zhang, G. Heymsfield, J. Dudhia, J.B. Halverson, R. Hood, and F. Marks Jr., 2006: Factors affecting the evolution of Hurricane Erin and the distributions of hydrometeors: Role of microphysical processes. J. Atmos. Sci., 63, 127-150.

Schneider, E., G.M. McFarquhar, B.F. Jewett, M. Gilmore, R.E. Hood and G.M. Heymsfield, 2006: Evaluation of cloud microphysical processes and their implications for intensification in numerical model simulations of Hurricane Dennis (2005). 12th Conf. Cloud Physics, Amer. Meteor. Soc., July, Madison, WI, Available from paper_113604.htm

Cotton, W.R., H. Zhang, G.M. McFarquhar and S.M. Saleeby, 2007: Should we consider polluting hurricanes to reduce their intensity? J. Weather Modification, 39, 70-73.

Halverson, J., P.L. Zaofeifa, M. Black, S. Braun, D. Cecil, M. Goodman, A. Heymsfield, G. Heymsfield, R. Hood, T. Krishnamurti, G. McFarquhar, J. Molinari, R. Rogers, J. Turk, C. Velden, D.-L. Zhang, E. Zipser and R. Kakar, 2007: NASA’s Tropical Cloud Systems and Processes (TCPS) Experiment: Investigating tropical cyclogenesis and hurricane intensity change. Bull. Amer. Meteor. Soc., 88,  867-882.

Zhang, H., G. McFarquhar, S. Saleeby and W.R. Cotton, 2007: Impacts of Saharan Dust as CCN on the evolution of an idealized tropical cyclone. Geophys. Res. Lett., 34, L14812, doi:10.1029/2007GL029876.

Meyers, E.C., G.M. McFarquhar, B.F. Jewett and M.S. Gilmore, 2008: Simulated and observed updrafts and downdrafts in Hurricane Dennis (2005): relationship to intensity. 28th Conf. Hurricanes Tropical Meteor., American Meteorological Society, May, Orlando, FL. Available from 28Hurricanes/techprogram/paper_138443.htm


Wisdom, A., and G.M. McFarquhar, 2008: Ice microphysics observations in tropical cyclones from CAMEX-4 and NAMMA. 28th Conf. Hurricanes Tropical Meteor., American Meteorological Society, May, Orlando, FL. Available from http://ams.

Zhang, H., G. M. McFarquhar, W.R. Cotton and Y. Deng, 2009: Direct and indirect impacts of Saharan dust acting as cloud condensation nuclei on tropical cyclone eyewall development. Geophys. Res. Lett., 36, L05802, doi:10.1029/2009GL037276.


Thesis arising from TCSP:

Dooley, Amanda L., “Ice microphysics observations in tropical cyclones from NAMMA”, M.S. thesis, 2008

Meyers, Eric, "Microphysical evolution related to vertical velocity distributions and rapid intensity changes of tropical cyclones: A combined approach using WRF simulations and TCSP/TRMM observations", M.S. thesis, anticipated 2009.

Zhang, Henian, “Impacts of Saharan dust as CCN on the evolution of an idealized tropical cyclone”, Ph.D. thesis, 2008.