NVAP_PW_MERGD_PDAILY is a legacy data set containing four types of files: total precipitable water and layered precipitable water, each are the total merged product in daily and pentad files.
The NVAP legacy data has been superseded by the NVAP-M data.
The NASA Water Vapor Project data set (NVAP) is a total column (integrated) water vapor data set comprised of a combination of radiosonde ... observations, Television and Infrared Operational Satellite (TIROS) Operational Vertical Sounder (TOVS), and Special Sensor Microwave/Imager (SSM/I) data sets. This is 5-year total and layered (1988-1992) global water vapor data set. The global layered water vapor data set is created by slicing the total water vapor data set using layered information that TOVS and radiosonde data provides. As a companion data set for analysis, STC-METSAT also prepared a global (over oceans only), integrated cloud liquid water data set (since the best global climate models now contain liquid water as an explicit variable). STC-METSAT developed methods to process the data at a daily time scale and 1o x 1o spatial resolution. This work has become an internationally accepted contribution to the World Climate Research Programme (WCRP).
Petty, G. W., 1990: On the response of the Special Sensor Microwave/Imager to the marine environment - Implications for atmospheric parameter retievals. Ph.D. dissertation, 291 pp., Univ. of Washington, Seattle.
Randel, D.L., T.H. Vonder Haar, M.A. Ringerud, G.L. Stephens, T.J. Greenwald, and C.L. Combs, July 1996: A New Global Water Vapor Dataset. Bull. Amer. Meteor. Soc., 77, 1233-1246.
Reale, A.L., M.D. Goldberg, and J.M. Daniels, 1989: Operational TOVS soundings using a physical approach. IGARRS '89 12th Canadian Symposium on Remote Sensing, Vancouver, B.C., 2653-2657.
Reynolds, R.W., 1988: A Real-Time Global Sea Surface Temperature Analysis. J. Climate, 1, 75-86.
Tjemkes, S.A., and G.L. Stephens, 1991: Space Borne Observations of Precipitable Water: Part I: SSM/I Observations and Algorithm. J. Geophys. Res., 96, 10941-10954.
Werbowtzki, A., 1981: Atmospheric sounding users guide. NOAA Tech. Report NESS 83, U.S. Dept. of Commerce, Washington, D.C.
Wu, X., J. J. Bates, and S.J.S. Khalsa, 1993: A Climatology of the Water Vapor Band Brightness Temperatures from NOAA Operational Satellites. J. Climate, 6, 1282-1300.