Water vapor distribution in the tropical troposphere is often bimodal, as opposed to normal or Gaussian. I have documented this bimodal nature of water vapor with an objective method of testing the bimodality. Working with my student, I have also investigated dry-air outbreaks from Africa into the tropical Atlantic Ocean and documented their pathways of westward propagation.

My current research related to tropical water vapor is on the following topics: (a) water vapor budget in the IntraAmericas See (IAS: the Gulf of Mexico and Caribbean Sea) and its transport into North America as a source of moisture for precipitation there, (b) water vapor transport by the shallow meridional circulation (see Research III), and (c) water vapor content within outbreaks of African dust and smoke (see Research IV).

My publications on this subject:

Mestas-Nunez, A. M., D.B. Enfield, C. Zhang, 2007: Water Vapor Fluxes over the Intra-Americas Sea: Seasonal and InterannualVariability and Associations with Rainfall. J. Clim., 20, 1918-1930. (reprint)

Mestas-Nunez, A. M., C. Zhang, D.B. Enfield, 2005: Uncertainties in Estimating Moisture Fluxes over the Intra-Americas Sea. J. Hydromet, 6, 696 - 709. (reprint)

Zhang, C. and J. Pennington, 2004: African dry-air outbreaks. JGR, 10 9, D20108, doi:10.1029/2003JD003978. (reprint)

Zhang, C., B.E. Mapes, and B.J. Soden, 2003: Bimodality in tropical water vapor. QJRMS, 129, 2847-2866. (reprint)

Zhang, C., and M.-D. Chou, 1999: Variability of water vapor, infrared radiative cooling, and atmospheric instability for deep convection in the equatorial western Pacific. J. Atmos. Sci., 56, 711-723. (reprint)

Brown, R. G., and C. Zhang, 1997: Variability of midtropospheric humidity and its effect on cloud-top height distribution during TOGA COARE. J. Atmos. Sci., 54, 2760-2774. ( reprint)