FILENAME: shbmcrs1micro.readme.txt DATASET TITLE: SHEBA: ETL Radar-based Cloud Microphysics Retrievals Version # 1, released on 11/30/01. CONTACTS: Matthew Shupe, matthew.shupe@noaa.gov, 303-497-6471. Taneil Uttal, taneil.uttal@noaa.gov, 303-497-6409 SUMMARY: Cloud microphysical properties are derived from retrieval techniques that combine ground-based radar and radiometer measurements from the SHEBA ice camp. Retrieved parameters include: particle size, water content, water path, particle concentration, and optical depth for all-ice, all-liquid, mixed-phase, and precipitating cloud types. The companion radar and radiometer files on which these retrievals are based are also available on the JOSS-CODIAC archive. TIME PERIOD: 10/20/97 - 10/1/98. INSTRUMENTS: 35 GHz Millimeter Cloud Radar (MMCR) - NOAA/ETL - Moran et al. 1998 23.8 and 31.4 GHz Microwave Radiometer (MWR) - DOE/ARM - Radiometrics WVR-1100. Atmospheric Emitted Radiance Interferometer (AERI) - DOE/ARM - Revercomb et al. 1993. TECHNIQUES: Microphysical retrieval techniques used to create this data set are partially described in Shupe et al. (2001). Three ice cloud retrieval techniques are applied: an empirical technique relating cloud ice water content to radar reflectivity, a radar-radiometer technique in which IR radiometer measurements are used to tune ice water content - radar reflectivity relationships (Matrosov 1999), and a relationship relating ice particle size to radar Doppler velocities (Matrosov et al. 2002). The first and third of these techniques, i.e. the radar-only techniques, are also applied to mixed-phase clouds under the assumption that the ice particles dominate the radar signal which responds to particle size to the fourth to sixth power. Therefore, mixed-phase clouds have retrieval values for only the ice component. Ice cloud optical depths were calculated using parameterizations of Matrosov (unpublished) and Fu and Liou (1993). Liquid cloud parameters are derived using two empirical relationships with radar reflectivity (Frisch et al. 2002) and by a combined radar-radiometer technique (Frisch et al. 1995 and 1998) in which MWR measurements provide a constraint on the total cloud liquid water path. Liquid cloud optical depths were calculated using parameterizations given by Slingo (1989) and Curry and Herman (1985). Snowfall parameters are derived with the formulation of Gunn and Marshall (1958). Rain parameters are derived with the formulation of Marshall and Palmer (1948). Drizzle parameters are derived from the Frisch et al. (1995) technique but are not included in this data set. Since multiple techniques are applied to some cloud scenes there may be multiple results for a given parameter. Users of the data should consult the given retrieval technique references and are encouraged to contact Matthew Shupe or Taneil Uttal to determine the relative reliability of different retrieval technique. A visual browser of cloud classification masks and retrieval results is available on the NOAA-ETL web at: http://www.etl.noaa.gov/arctic/sheba/index.html. SAMPLING RESOLUTION: The microphysical retrievals have a 1-minute and 45-meter grid resolution and are based on original data on a 10-second and 45-meter grid resolution. FILE FORMAT: NetCDF. PARAMETERS (units): time - Time of observations (decimal hours). 1-min intervals. height - Height of observations (km AGL). 45-m range gates. mask - Retrieval type classification mask. mask_cert - (Not utilized) tausw_be - Best estimated column SW extinction optical depth (unitless). idmn - Ice particle mean diameter, Matrosov 1999 technique (microns). iwc - Ice water content, Matrosov 1999 technique (g/m3). iwp - Ice water path, Matrosov 1999 technique (g/m2). iconc - Ice particle concentration, Matrosov 1999 technique (1/cm3). itausw - Ice cloud SW extinction optical depth, Matrosov 1999 technique (unitless). itaulw - Ice cloud LW absorption optical depth, Matrosov 1999 results (unitless). iacoeff - Ze-IWC regression coefficient, Matrosov 1999 technique (unitless). iextcoeff - Ice cloud visible extinction coefficient, Matrosov 1999 results (1/m). itauve - Ice cloud visible extinction optical thickness, Matrosov 1999 results (unitless). idmn_s - Ice particle mean diameter, empirical technique (microns). iwc_s - Ice water content, empirical technique (g/m3). iwp_s - Ice water path, empirical technique (g/m2). iconc_s - Ice particle concentration, empirical technique (1/cm3). itausw_s - Ice cloud SW extinction optical depth, empirical results (unitless). itaulw_s - Ice cloud LW absorption optical depth, empirical results (unitless). iextcoeff_s - Ice cloud visible extinction coefficient, empirical results (unitless). itauve_s - Ice cloud visible extinction optical thickness, empirical results (unitless). idmn_d - Ice particle mean diameter, Matrosov 2002 technique (microns). iwc_d - Ice water content, Matrosov 2002 technique (g/m3). iwp_d - Ice water path, Matrosov 2002 technique (g/m2). iconc_d - Ice particle concentration, Matrosov 2002 results (1/cm3). itausw_d - Ice cloud SW extinction optical depth, Matrosov 2002 results (unitless). itaulw_d - Ice cloud LW absorption optical depth, Matrosov 2002 results (unitless). iextcoeff_d - Ice cloud visible extinction coefficient, Matrosov 2002 technique (unitless). itauve_d - Ice cloud visible extinction optical thickness, Matrosov 2002 technique (unitless). assess_d - (Not utilized) lre - Liquid droplet effective radius, Frisch 1995 technique (microns). lwc - Liquid water content, Frisch 1995 technique (g/m3). lwp - Liquid water path, MWR-retrieved (g/m2). lconc - Liquid droplet column averaged concentration, Frisch 1995 technique (1/cm3). ltausw - Liquid cloud SW extinction optical depth, Frisch 1995 results (unitless). ltaulw - Liquid cloud LW absorption optical depth, Frisch 1995 results (unitless). lre_s1 - Liquid droplet effective radius, Empirical 1 technique (microns). lre_s2 - Liquid droplet effective radius, Empirical 2 technique (microns). lwc_s1 - Liquid water content, Empirical 1 technique (g/m3). lwc_s2 - Liquid water content, Empirical 2 technique (g/m3). lwp_s1 - Liquid water path, Empirical 1 technique (g/m2). lwp_s2 - Liquid water path, Empirical 2 technique (g/m2). lconc_s2 - Liquid droplet concentration, Empirical 2 technique (1/cm3). ltausw_s1 - Liquid cloud SW extinction optical depth, Empirical 1 results (unitless). ltaulw_s1 - Liquid cloud LW absorption optical depth, Empirical 1 results (unitless). ltausw_s2 - Liquid cloud SW extinction optical depth, Empirical 2 results (unitless). ltaulw_s2 - Liquid cloud LW absorption optical depth, Empirical 2 results (unitless). srate - Water equivalent snowfall rate, Gunn and Marshall technique (mm/hr). ssize - Snow particle size, Gunn and Marshall technique (microns). smass - Snow mass content, Gunn and Marshall technique (g/m3). sconc - Snow particle concentration, Gunn and Marshall results (1/cm3). rrate - Rainfall rate, Marshall and Palmer technique (mm/hr). rsize - Rain drop size, Marshall and Palmer technique (microns). rmass - Rain mass content, Marshall and Palmer technique (g/m3). rconc - Rain drop concentration, Marshall and Palmer results (1/cm3). drate - Drizzle rate or flux, Frisch 1995 technique (mm/hr). Not currently included. dsize - Drizzle drop modal radius, Frisch 1995 technique (microns). Not currently included. dmass - Drizzle mass content, Frisch 1995 technique (g/m3). Not currently included. dconc - Drizzle drop concentration, Frisch 1995 results (1/cm3). Not currently included. KNOWN ERRORS: For the time period of October 20, 1997 (i.e. the beginning of the experiment) until December 9, 1997 one of the MMCR's four operational modes was producing erroneous information due to a faulty hardware component. Information from this mode was omitted during the stated time period. Since the omitted mode was the most sensitive, some portion of cloud returns may have been missed by the radar during this time period. The missed returns would have occurred primarily in high altitude cirrus clouds containing very small particles. REFERENCES: Curry, J.A., and G.F. Herman, 1985: Infrared radiative properties of summertime Arctic stratus clouds, J. Appl. Meteor., 24, 525-538. Frisch, A. S., C. W. Fairall, and J. B. Snider, 1995: Measurements of stratus cloud and drizzle parameters in ASTEX with a Ka-band Doppler radar and microwave radiometer, J. Atmos. Sci., 52, 2788-2799. Frisch, A. S., G. Feingold, C. W. Fairall, T. Uttal, and J. B. Snider, 1998: On cloud radar and microwave radiometer measurements of stratus cloud liquid water profiles, J. Geophys. Res., 103, 23,195-23,197. Frisch, A. S., M. D. Shupe, S. Y. Matrosov, I. Djalalova, G. Feingold, and M. Poellot, 2002: On the Retrieval of Effective Radius with Cloud Radars. J. Geophys. Res., in press. Fu, Q., and K.N. Liou, 1993: Parameterization of the radiative properties of cirrus clouds. J. Atmos. Sci., 50, 2008-2025. Gunn, K.L.S. and J.S. Marshall, 1958: The distribution with size of aggregate snowflakes, J. Meteorol., 15, 452-461. Marshall, J.S. and W. Palmer, 1948: The distribution of raindrops with size, J. Meteorol., 5, 165- 166. Matrosov, S. Y., 1999: Retrievals of vertical profiles of ice cloud microphysics from radar and IR measurements using tuned regressions between reflectivity and cloud parameters, J. Geophys. Res., 104, 16,741-16,753. Matrosov, S.Y., A.V. Korolev, and A.J. Heymsfield, 2002: Profiling cloud ice mass and particle characteristic size from Doppler radar measurements, J. Atmos. Oceanic Technol., in press. Moran, K.P., B.E. Martner, M.J. Post, R.A. Kropfli, D.C. Welsh, and K.B. Widener, 1998: An unattended cloud-profiling radar for use in climate research, Bull. Am. Meteorol. Soc., 79, 443- 455. Revercomb, H., F. A. Best, R. G. Dedecker, R. P. Dirkx, R. A. Herbsleb, R. O. Knuteson, J. F. Short, and W. L. Smith, 1993: Atmospheric Emitted Radiance Interferometer (AERI) for ARM. Preprints, Fourth Symp. on Global Change Studies, Anaheim, CA, Amer. Meteor. Soc., 46-49. Shupe, M.D., T. Uttal, S.Y. Matrosov, and A.S. Frisch, 2001: Cloud water contents and hydrometeor sizes during the FIRE - Arctic Clouds Experiment, J. Geophys. Res., 106, 15,015- 15,028. Slingo, A., 1989: A GCM parameterization for the shortwave radiative properties of water clouds, J. Atmos. Sci., 46, 1419-1427. Westwater,E.R., Y. Han, M. D. Shupe, S. Y. Matrosov, 2001: Analysis of integrated cloud liquid and precipitable water vapor retrievals from microwave radiometers during SHEBA, J. Geophys. Res., 106, 32,019-32,030.