1.  TITLE

1.1  Data Set Identification.

     Surface Shortwave and Longwave Radiation Fluxes.

     (Monthly Mean Fluxes ; NASA/LaRC)

1.2  Data Base Table Name.

     Not applicable.

1.3  CD-ROM File Name. 


     Where nnnn is the last four characters of the parameter directory name 
     (The Langley radiation data has 5 types of parameters, see table below). 
     Note:  capital letters indicate fixed values that appear on the CD-ROM 
     exactly as shown here, lower case indicates characters (values) that 
     change for each path and file.

     The format used for the filenames is: YyyMmm.sfx, where yy is the last 
     two digits of the year (e.g., Y87=1987), and mm is the month of the year 
     (e.g., M12=December).  The filename extension (.sfx), identifies the 
     parameter in the file.  Below is the list of actual filenames 
     extensions, directory names and full parameter names:

     Parameter Description              Parameter Directory Name   Extension
     Surface Shortwave Downward Flux    SUR_SWDN                         SSD
     Surface Shortwave Net Flux         SUR_SWNT                         SSN
     Surface Longwave Downward Flux     SUR_LWDN                         SLD
     Surface Longwave Net Flux          SUR_LWNT                         SLN
     Surface Total Net Radiation Flux   SUR_TONT                         STN

1.4  Revision Date Of This Document.

     April 5, 1995.

                         2.  INVESTIGATOR(S)

2.1  Investigator(s) Name And Title.

     Mr. Wayne Darnell
     Radiation Sciences Branch
     NASA Langley Research Center

2.2  Title Of Investigation.

     Application of Long-Term Surface Radiation Data for Climate Studies

2.3  Contacts (For Data Production Information).

              |      Contact 1     |    Contact 2        |     Contact 3      |
2.3.1 Name    |Mr. Wayne L. Darnell|Ms. Nancy Ritchey    |Dr. Shashi Gupta    |
2.3.2 Address |Radiation Sciences  |Lockheed Engineering |Lockheed Engineering|
              |Branch              |& Sciences Co.       |& Sciences Co.      |
              |NASA/LaRC           |144 Research Dr      | 144  Research Dr   |
      City/St.|Hampton, VA         |Hampton, VA          |Hampton, VA         |
      Zip Code|23681-0001          |23666                |23666               |
2.3.3 Tel.    |(804)864-5685       |(804)766-9655        |(804)766-9653       |
2.3.4 Email   |w.l.darnell@larc.   |ritchey@solir.larc.  |gupta@solir.larc.   |
              |          |           |          |

2.4  Requested Form of Acknowledgment.

     Please cite the following publication when these data are used:

      Darnell, W. L., W. F. Staylor, S. K. Gupta, N. A. Ritchey, and A. C. 
          Wilber, 1992.  Seasonal variation of surface radiation budget 
          derived from ISCCP-C1 data.  J. Geophys. Res., 97:15741-15760.

                            3.  INTRODUCTION

3.1  Objective/Purpose.

     The objective of this study was to produce daily and monthly averages of 
     surface radiative fluxes over the entire globe for climate and other 

3.2  Summary of Parameters.

     This work was a study of radiative fluxes at the Earth's surface.  The 
     data set contains downward and net fluxes of LW and SW radiation as well 
     as total net (LW + SW) flux. 

3.3  Discussion.

     The surface fluxes were computed using meteorological data available from 
     the ISCCP, TOA clear-sky albedos from ERBE, and radiation schemes 
     developed by the prencipal investigator and his coworkers.  The 
     essentials of the method are given in Darnell et al. (1992).  For greater 
     details of the methodology the user is referred to Darnell et al. (1988), 
     Gupta (1989), Gupta et al. (1992), and Whitlock et al. (1993).

                        4.  THEORY OF MEASUREMENTS

No measurements were made directly by the investigators.  The necessary inputs 
all came from satellite sources.  ISCCP-C1 data sets were chosen as inputs 
here because most of the meteorological data for these data came from 
operational satellite sources.  Also, the cloud parameters derived by ISCCP 
are about the best currently available.  The data coverage is global.

For an explanation of the ISCCP C1 data see Brest and Rossow (1992), Desormeux 
et al. (1993), Rossow and Garder (1993a), Rossow and Garder (1993b), Rossow et 
al. (1993), Rossow and Schiffer (1991), Schiffer and Rossow (1983), Schiffer 
and Rossow (1985).  The angular models used in the inference model are 
described in Suttles et. al., (1988).

                            5.  EQUIPMENT

The basic instruments which made the measurements for ISCCP were the visible 
and infrared imaging radiometers on-board geostationary and polar Sun-
synchronous satellites which were operational during the data period.  However 
for the SRB project, only the final ISCCP-C1 products were used.  The details 
of the various satellite missions are beyond the scope of the SRB project.  
Therefore, the various subsections of Sec. 5 do not apply to this project.

5.1  Instrument Description.

     Not applicable.

     5.1.1  Platform (Satellite, Aircraft, Ground, Person...).

            Not applicable.

     5.1.2  Mission Objectives.

            Not applicable.

     5.1.3  Key Variables.

            Not applicable.

     5.1.4  Principles of Operation.

            Not applicable.

     5.1.5  Instrument Measurement Geometry.

            Not applicable.

     5.1.6  Manufacturer of Instrument.

            Not applicable.

5.2  Calibration.

     For an explanation of the ISCCP C1 data calibration, see Brest and Rossow 
     (1992), Desormeux et al. (1993).

     5.2.1  Specifications.

            Not applicable.


                     Not applicable.

     5.2.2  Frequency of Calibration.

            Not applicable.

     5.2.3  Other Calibration Information.

            Not applicable.

                          6.  PROCEDURE

6.1  Data Acquisition Methods.

     The data sets described in this document were acquired by the Goddard
     Distributed Active Archive Center (GDAAC) from W. L. Darnell NASA
     Langley Research Center.  The ISCCP-C1 data are currently available 
     from User and Data Services at the Langley DAAC, NASA Langley Research 

6.2  Spatial Characteristics.

     The original data was supplied on an ISCCP equal-area grid that had a 
     spatial resolution of 280 by 280 km. The Goddard DAAC converted this data 
     to a 1 x 1 degree lat/lon equal-area grid (see section 9.3.1 for 

     6.2.1  Spatial Coverage.

            The coverage is global.  Data in each file are ordered from North 
            to South and from West to East beginning at 180 degrees West and 
            90 degrees North.  Point (1,1) represents the grid cell centered 
            at 89.5 N and 179.5 W (see section 8.4).

     6.2.2  Spatial Resolution.

            The data are given in an equal-angle lat/long grid that has a 
            spatial resolution of 1 X 1 degree lat/long.

6.3  Temporal Characteristics.

     6.3.1  Temporal Coverage.

            January 1987 through December 1988.

     6.3.2  Temporal Resolution.

            Monthly mean.

                           7.  OBSERVATIONS

7.1  Field Notes.

     Not applicable.

                         8.  DATA DESCRIPTION

8.1  Table Definition With Comments.

     Not applicable.

8.2  Type of Data.

|                 8.2.1                  |               |          |          |
|Parameter/Variable Name                 |               |          |          |
|    |               8.2.2               |     8.2.3     |  8.2.4   |  8.2.5   |
|    |Parameter/Variable Description     |Range          |Units     |Source    |
|SUR_LWDN                                |               |          |          |
|    |Surface longwave downward          |min = 50.,     |[Watts]   |Computed  |
|    |radiation flux                     |max = 750.,    |[m^-2]    |from      |
|    |                                   |missing = -999.|          |ISCCP-C1  |
|SUR_LWNT                                |               |          |          |
|    |Surface longwave net radiation     |min = -250.,   |[Watts]   |computed  |
|    |flux                               |max = 50.,     |[m^-2]    |from      |
|    |                                   |missing = -999.|          |ISCCP-C1  |
|SUR_SWDN                                |               |          |          |
|    |Surface shortwave downward         |min = 0.,      |[Watts]   |Computed  |
|    |radiation flux (insolation)        |max = 500.,    |[m^-2]    |from      |
|    |                                   |missing = -999.|          |ISCCP-C1  |
|SUR_SWNT                                |               |          |          |
|    |Surface shortwave net radiation    |min = 0.,      |[Watts]   |Computed  |
|    |flux (absorbed)                    |max = 500.,    |[m^-2]    |from      |
|    |                                   |missing = -999.|          |ISCCP-C1  |
|SUR_TONT                                |               |          |          |
|    |Surface total net radiation flux   |min = -100.,   |[Watts]   |Computed  |
|    |(LW_NET + SW_NET)                  |max = 300.,    |[m^-2]    |from      |
|    |                                   |missing = -999.|          |ISCCP-C1  |

8.3  Sample Data Base Data Record.

     Not applicable.

8.4  Data Format.

     The CD-ROM file format is ASCII, and consists of numerical fields of 
     varying length, which are space delimited and arranged in columns and 
     rows.  Each column contains 180 numerical values and each row contain 360 
     numerical values.  

          Grid arrangement

             I  = 1 IS CENTERED AT 179.5W
             J  = 1 IS CENTERED AT 89.5N

             90N - | - - - | - - - | - - - | - -
                   | (1,1) | (2,1) | (3,1) |
             89N - | - - - | - - - | - - - | - -
                   | (1,2) | (2,2) | (3,2) |
             88N - | - - - | - - - | - - - | - -
                   | (1,3) | (2,3) | (3,3) |
             87N - | - - - | - - - | - - - |
                  180W   179W    178W   177W


8.5  Related Data Sets.

     Surface and TOA shortwave radiation and photosynthetically active 
     radiation data set's. (on this CD-ROM.)
     ISCCP-C1 data, see section 14.3.
     ERBE-S4 data, see section 14.3.
     Surface Shortwave Down Radiation NASA/LaRC, ECMWF Hybrid (on CD-ROM 
     Vol. 5).
     Surface Longwave Down Radiation NASA/LaRC, ECMWF Hybrid (on CD-ROM 
     Vol. 5).

                         9.  DATA MANIPULATIONS

9.1  Formulas.

     For various formulas and details of the algorithm, the user is referred 
     to Darnell et al. (1992).

     9.1.1  Derivation Techniques/Algorithms.

            The LW technique:

            The LW radiative fluxes (both LWDN and LWNT) are computed using 
            a fast parameterization which is based on detailed radiative 
            transfer computations (Gupta 1989; Gupta et al. 1992).  The inputs 
            for the computation are taken from the ISCCP-C1 data sets.  LWDN 
            is computed as
                        LWDN = F1 + F2 * AC,
            where F1 is the clear-sky LWDN, F2 is the cloud forcing factor, 
            and AC is the fractional cloud cover.  LWNET is computed as
                        LWNT = LWDN - SIGMA * TS^4,
            where SIGMA is the Stefan-Boltzman constant (=5.67E-08 [W][m^-2]
            [K^-4]), and TS is the surface temperature.
            Details of the development and application of the 
            parameterizations of F1 and F2 in terms of the meteorological 
            parameters available from ISCCP-C1 data are given in Gupta (1989) 
            and Gupta et al. (1992).  A very brief description of the 
            parameterizations is presented here. 

            The clear-sky LWDN (F1) is computed as
                    F1 = ( A0 + A1 * V + A2 * V^2 + A3 * V^3 ) * TE^3.7,
            where V = ln W, and W is the total water vapor burden of the 
            atmosphere.  TE is an effective emitting temperature of the lower 
            troposphere, and is computed as
                        TE = KS*TS + K1*T1 + K2*T2,
            where TS is the surface temperature, T1 is the mean temperature of 
            the first layer in the ISCCP-C1 data (surface to 800[mb]), and T2 
            is the same for the second layer (800[mb] to 680[mb]).  KS, K1, 
            and K2 are weighting factors with values of 0.60, 0.35, and 0.05 
            respectively.  The regression coefficients A0, A1, A2, and A3 have 
            the following values:

                          A0 = 1.791E-07,
                          A1 = 2.093E-08,
                          A2 = -2.748E-09,
                          A3 = 1.184E-09.
            The cloud forcing factor (F2) is computed as
                   F2 = TCB^4 / ( B0 + B1 * WC + B2 * WC^2 + B3 * WC^3 ),
            where TCB is the cloud-base temperature, WC is the water vapor
            burden below the cloud base, and B0, B1, B2, and B3 are regression 
            coefficients with the following values:

                          B0 = 4.990E+07,
                          B1 = 2.688E+06,
                          B2 = -6.147E+03,
                          B3 = 8.163E+02.
            All fluxes represented here are in [W][m^-2], temperatures in deg. 
            K, and water vapor burdens in [kg][m^-2].  Cloud-base pressure is 
            obtained by combining cloud-top pressure (available from ISCCP-C1
            data) with climatological estimates of cloud thickness which 
            depend upon cloud height and latitude.  TCB and WC are computed 
            from the available ISCCP-C1 data using the procedure described in 
            Gupta (1989).  The above equation for F2 is used as such when the 
            pressure difference between the surface and cloud base is greater 
            than 200 [mb].  When the pressure difference is greater than or 
            equal to 200 [mb], a modified form of this equation, as described 
            in Gupta et al. (1992), is used.

            The SW technique:

            The shortwave algorithm was developed at NASA Langley Research
            Center by W. F. Staylor.  It is a parameterized/physical model 
            that utilizes ISCCP-C1 data (Rossow and Schiffer, 1991) as its 
            primary input data.  The current model is a modified version of an 
            earlier model by Darnell et al. (1988).  A recent application of 
            the method is given in Darnell et al. (1992).
            Instantaneous downward SW at the surface (insolation) can be
            estimated using the model presented in Darnell et al. (1988).  
            Downward SW flux at the surface is the product of insolation at 
            the TOA, clear-sky atmospheric transmittance and cloud 
            Daily insolation requires time integration of the instantaneous 
            values from sunrise to sunset.  Insolation at the TOA is a product
            of the cosine of the solar zenith angle and the distance-corrected
            solar flux, which is calculated daily using 1365 [W][m^-2] as the 
            solar flux and 1[astronomical units] as the Earth-Sun distance.
            Atmospheric transmittance is a function of surface pressure, 
            surface albedo, aerosols, and the effective clear-sky atmospheric 
            optical depth.  The first three terms account for the atmospheric 
            backscatter of surface reflected rays.  The effective clear-sky 
            atmospheric optical depth is a vertical attenuation factor for 
            solar energy and it is the sum of all absorption and scattering 
            processes. These processes include absorption and scattering due 
            to gases and  aerosols.  The broadband absorption due to water 
            vapor and ozone,  and Rayleigh attenuation are estimated using 
            Lacis and Hansen (1974).  The broadband absorption due to oxygen 
            and carbon dioxide are approximated using Yamamoto (1962).  
            Aerosol attenuation is based on World Climate Program models 
            (World Climate Research Program, 1983) and is a function of 
            aerosol optical depth, an asymmetry factor and the single-
            scattering albedo.  It should be noted that the Rayleigh and 
            aerosol attenuation terms are concerned only with backscattering 
            and/or absorption, but not with forward scattering of flux which 
            reaches the surface.
            Cloud transmittance is based on a threshold technique which 
            relates boundary values of TOA reflectances for overcast and 
            clear-sky conditions and actual measured conditions (from ISCCP).  
            Overcast reflectances are estimated from a model by Staylor (1985) 
            using the cosines of viewing zenith angle and solar zenith angle, 
            and overcast coefficients.  These coefficients are determined 
            monthly for each ISCCP satellite using data for non-snow covered, 
            totally overcast regions having mean cloud optical depths within 
            the top 5 percentile of all observations.  Clear-sky reflectances 
            are determined by one of several methods depending on the snow 
            cover and surface type.  Over oceans, the cosines of viewing 
            zenith angle and solar zenith angle, along with clear-sky 
            coefficients are used.  These coefficients are determined for 
            totally-clear oceans for each satellite every month.  For snow-
            free land regions or land regions  in which the snow cover does 
            not fluctuate by more than 10 percent during the month, daily TOA 
            clear-sky reflectance values are  computed from the clear-sky 
            pixels.  The monthly minimum value is used for the entire month.  
            If the snow cover changes by more than 10 percent during the month 
            (determined for 5-day intervals), then the above procedure is 
            applied to the 5-day periods.  Measured instantaneous reflectances 
            are the pixel-weighted average of the clear and cloudy 
            reflectances.  If no value exists for a day (occurs most 
            frequently in polar regions), a fill value is provided by one of 
            two methods.  If a value exists for a longitudinally adjacent 
            region for that day, it is used.  If it does not exist, then the 
            previous day's value is used.  This procedure is expanded 
            spatially, then temporally until a non-fill value is found.
            Daily surface albedo for all-sky conditions is a function of the 
            daily overcast albedo, the daily clear-sky albedo and cloud 
            transmittance.  Data from Budyko (see Payne 1972) and 
            Ter-Markariantz (see Kondratyev 1973) were used to estimate 
            clear-sky surface albedos over oceans.  Estimates of daily 
            overcast albedos over oceans are based on the fact that under 
            overcast conditions the effective zenith angle of the diffuse rays 
            is about 53 [degrees] for all zenith angles (cosine = 0.6) and 
            therefore is a constant value of 0.065.  Clear-sky ERBE TOA 
            albedos were used to estimate clear-sky surface albedos over land.  
            This approach avoided the need for spectral conversions from 
            narrowband to broadband and from radiances to albedos (Staylor and 
            Wilber 1990).  Overcast albedos over land are estimated using the 
            clear-sky land albedo and the cosine of the solar zenith angle.

            Total net flux:

            Total net flux is the sum of net LW flux and net SW flux.
            For further information, the user is referred to Darnell et 
            al. (1992).

9.2  Data Processing Sequence.

     Details of processing are discussed in Darnell et al. (1992).

     9.2.1  Processing Steps and Data Sets.

            Details of processing are discussed in Darnell et al. (1992).

     9.2.2  Processing Changes.

            This is the first version of this data set.

9.3  Calculations.

     The user is referred to Darnell et al. (1992).

     9.3.1  Special Corrections/Adjustments.

            Below is a description of the re-gridding process done by the 
            Goddard DAAC:

            Physical Lay Out of Original Data:  24 files, with each file
            representing the monthly means for the entire globe.  Within each 
            file, each line consists of a grid index, latitude index, 
            longitude index, followed by the five radiation parameters.  The 
            data are gridded using the ISCCP method of equal area gridding.  
            The equal area map is defined by the area of a 2.5 x 2.5 degree 
            cell at the equator.  There are 6596 cells in this map grid.  All 
            map cells are determined by a constant 2.5 degree increment in 
            latitude and a variable longitude increment.  The longitude 
            increment is selected to provide an integer number of cells in a 
            latitude zone and to give a cell area as close to that of the 
            equatorial cell as possible.

            Logical Lay Out of Original Data:  Within each file, the data 
            start at the 0 deg. longitude, and -90 deg. latitude, progressing 
            eastward to 360 deg. longitude, and then northward to 90 deg. 

            Processing Steps done by the Goddard DAAC:  Regrid each latitude 
            and longitude band of data by implementing the following steps:

            1) Replicated every data value in each latitude band 360 times, 
               assigning them to a temporary array.  For latitude band #1, 
               there were 3 values, each value is replicated 360 times 
               producing a temporary array of 1080 data values.  The number of 
               original values in a latitude band increases as you move toward 
               the equator, where there were 144 data values.  If the  
               latitude band originally had 144 data values, this would also  
               be replicated 360 producing a temporary array of 51840 data  
            2) For latitude band #1 the first three (temporary array) data 
               values are summed and then divided by the number of original 
               values (3) for that latitude band. This was repeated 359 more 
               times, for every three (temporary array) data values, in affect 
               performing a linear interpolation of the data within the 
               latitude band.  If the latitude band had 144 data values, every 
               144 (temporary array) data values would be summed and then 
               divided by 144.
            3) Step 1 and 2 were repeated until all latitude bands have been 
            4) A similar method, discussed above, was used for regridding each 
               longitude band of data.  The difference was that the number of 
               data values in each longitude band did not vary (there were 
               always 144 data values), and the replication was 180.
            5) The resulting array of data values were then split and shifted 
               from 0 longitude -> 360 longitude to -180 longitude -> 180 
            6) These data were then flipped from -180 longitude, -90 latitude 
               to -180 longitude, 90 latitude.

9.4  Graphs and Plots.

     The user is referred to Darnell et al. (1992).

                          10.  ERRORS

10.1  Sources of Error.

      Errors in the fluxes come from the radiation modeling and from the 
      meteorological data.  Modeling errors are systematic and are generally 
      small.  Errors from meteorological data are both random and systematic.  
      For a detailed analysis of errors the reader is referred to Gupta et al.

10.2  Quality Assessment.

      10.2.1  Data Validation by Source.

              The SW fluxes obtained with this model were validated with 
              insolation measurements obtained from a large number of sites.  
              See Darnell et al. (1988) for details.  The LW fluxes obtained 
              with the model used here were validated with surface 
              measurements from 4 sites in the United States.  See Darnell et 
              al. (1986) for details of LW validation.

      10.2.2  Confidence Level/Accuracy Judgment.

              While larger sources of errors are identified and quantified, 
              smaller sources, e.g. the occurrence of fog, are difficult to 
              quantify.  These definitely contribute some to the bias in the

      10.2.3  Measurement Error for Parameters and Variables.

              Random errors on monthly average SW and LW fluxes are about 
              10-12 [W] [m^-2].  No estimates are available for systematic 

      10.2.4  Additional Quality Assessment Applied.


                             11.  NOTES

11.1  Known Problems With The Data.

      There are no known gaps in these data sets.

11.2  Usage Guidance.

      Errors in polar regions may be larger than those quoted in Section 10.

11.3  Other Relevant Information.


                           12.  REFERENCES

12.1  Satellite/Instrument/Data Processing Documentation.

      ERBE Data Management Team, 1991. "ERBE Data Management System, The
          Regional, Zonal and Global Averages, S-4 Users Guide." NASA/Langley,
          Hampton, Virginia.
      Rossow, W. B. L. C. Garder, P. J. Lu and A. Walker, 1988.  International
          Satellite Cloud Climatology Project (ISCCP):  Documentation of cloud
          data, Tech. Doc. WMO/TD 266, 75 pp., World Climate Research 
          Programme, Geneva.
      World Meteorological Organization (WMO), 1984. Solar radiation and
          radiation balance data, July 1983, World Radiat. Data Center, 
          Voeikov Main Geophys. Observ., St. Petersburg, Russia.

12.2  Journal Articles and Study Reports.

      Brest, C.L., and W.B. Rossow, 1992. Radiometric calibration and 
          monitoring of NOAA AVHRR data for ISCCP. Int. J. Remote Sensing, 
      Darnell, W. L., S. K. Gupta, and W. F. Staylor, 1986.  Downward longwave 
          surface radiation from Sun-synchronous satellite data:  Validation 
          of methodology.  J. Clim. Appl. Meteorol., 25:1012-1021.
      Darnell, W. L., W. F. Staylor, S. K. Gupta, and F. M. Denn, 1988.  
          Estimation of surface insolation using Sun-synchronous satellite 
          data. J. Climate, 1:820-835.
      Darnell, W. L., W. F. Staylor, S. K. Gupta, N. A. Ritchey, and A. C. 
          Wilber, 1992.  Seasonal variation of surface radiation budget 
          derived from ISCCP-C1 data.  J. Geophys. Res., 97:15741-15760.
      Desormeaux, Y., W.B. Rossow, C.L. Brest and G.G. Cambell, 1993. 
          Normalization and calibration of geostationary satellite radiances 
          for ISCCP. J. Atmos. Ocean Tech., 10:304-325.
      Gupta, S. K., 1989.  A parameterization for longwave surface radiation 
          from Sun-synchronous satellite data.  J. Climate, 2:305-320.
      Gupta, S. K., W. L. Darnell, and A. C. Wilber, 1992.  A parameterization 
          of longwave surface radiation from satellite data:  Recent
          improvements.  J. Appl. Meteorol., 31:1361-1367.
      Gupta, S. K., A. C. Wilber, W. L. Darnell, and J. T. Suttles, 1993.  
          Longwave surface radiation over the globe from satellite data:  An 
          error analysis.  Int. J. Remote Sens., 14:95-114.
      Lacis, A. A. and J. E. Hansen, 1974.  A parameterization for the
          absorption of solar radiation in the earth's atmosphere.  J.
          Atmos. Sci., 31:118-133.
      Kondratyev, K. Y., 1973.  Radiation characteristics of the atmosphere
          and the Earth's surface.  NASA TTF-678, 580pp.
      Payne, R. E., 1972.  albedo of the sea surface.  J. Atmos. Sci., 
      Rossow,W.B., and L.Garder, 1984. Selection of a map grid for data
          analysis and archival. J.Climate and Appl. Meteor., 23:1253-57.
      Rossow, W. B., and R. A. Schiffer, 1991.  ISCCP cloud data products.  
          Bull. Amer. Meteor. Soc., 72:2-20.
      Rossow, W.B., and L.C. Garder, 1993a. Cloud detection using satellite 
          measurements of infrared and visible radiances for ISCCP. J. 
          Climate, 6:2341-2369.
      Rossow, W.B., and L.C. Garder, 1993b. Validation of ISCCP cloud 
          detections. J. Climate, 6:2370-2393.
      Rossow, W.B., A.W. Walker and L.C. Garder, 1993: Comparison of ISCCP 
          and other cloud amounts. J. Climate, 6:2394-2418.
      Staylor, W. F., 1985.  Reflection and emission models for clouds
          derived from Nimbus 7 Earth radiation budget scanner
          measurements.  J. Geophys. Res., 90:8075-8079.
      Staylor, W. F., and A. C. Wilber, 1990.  Global surface albedos 
          estimated from ERBE data.  Proceedings of AMS Conf. on Atmospheric
          Radiation,  July 23-27, 1990, San Francisco, CA, pp 231-236.
      Whitlock, C. H., T. P. Charlock, W. F. Staylor, R. T. Pinker, I. Laszlo, 
          R. C. DiPasquale, and N. A. Ritchey, 1993.  WCRP Surface Radiation
          Budget Shortwave Data Product Description - Version 1.1.  NASA
          Technical Memo 107747, NTIS, Springfield, Virginia.  
      World Climate Research Program, 1983.  Experts meeting on aerosols
          and their climate effects.  A. Deepak and H. E. Gerber editors,
          WCP-55, 107 pp.
      Yamamoto, G., 1962.  Direct absorption of solar radiation by
          atmospheric water vapor, carbon dioxide, and molecular oxygen.
          J. Atmos. Sci., 19:182-188.

12.3  Archive/DBMS Usage Documentation.

      Contact the EOS Distributed Active Archive Center (DAAC) at NASA Goddard 
      Space Flight Center (GSFC), Greenbelt Maryland (see Section 13 below).
      Documentation about using the archive or information about access to the 
      on-line information system is available through the GSFC DAAC User 
      Services Office.

                             13.  DATA ACCESS

13.1  Contacts for Archive/Data Access Information.

      GSFC DAAC User Services
      NASA/Goddard Space Flight Center
      Code 902.2
      Greenbelt, MD 20771

      Phone:     (301) 286-3209
      Fax:       (301) 286-1775

13.2  Archive Identification.

      Goddard Distributed Active Archive Center
      NASA Goddard Space Flight Center
      Code 902.2
      Greenbelt, MD 20771

      Telephone:  (301) 286-3209
      FAX:        (301) 286-1775

13.3  Procedures for Obtaining Data.

      Users may place requests by accessing the on-line system, by sending 
      letters, electronic mail, FAX, telephone, or personal visit.

      Accessing the GSFC DAAC Online System:

      The GSFC DAAC Information Management System (IMS) allows users to 
      ordering data sets stored on-line.  The system is open to the public.

      Access Instructions:

      Node name:
      Node number:
      Login example: telnet
      Username:  daacims
      password:  gsfcdaac

      You will be asked to register your name and address during your first

      Ordering CD-ROMs:

      To order CD-ROMs (available through the Goddard DAAC) users should 
      contact the Goddard DAAC User Support Office (see section 13.2).

13.4  GSFC DAAC Status/Plans.

      The ISLSCP Initiative I CD-ROM is available from the Goddard DAAC.


14.1  Tape Products.


14.2  Film Products.


14.3  Other Products.

      ISCCP-C1 and ERBE-S4 data, can be acquired from the Langley DAAC.  The 
      Langley DAAC User and Data Services Office may be contacted as follows:

             User and Data Services
             Langley DAAC
             Mail Stop 157B
             NASA Langley Research Center
             Hampton, VA 23681-0001

             Telephone:  (804) 864-8656
             FAX:        (804) 864-8807

                       15.  GLOSSARY OF ACRONYMS

CD-ROM        Compact Disk (optical), Read Only Memory
DAAC          Distributed Active Archive Center
ERBE          Earth Radiation Budget Experiment
EOS           Earth Observing System
GCM           General Circulation Model of the atmosphere
GSFC          Goddard Space Flight Center
ISCCP         International Satellite Cloud Climatology Project
IDS           Inter Disciplinary Science
ISLSCP        International Satellite Land Surface Climotology Project
LaRC          Langley Research Center
LW            Longwave Radiation
LWDN          Longwave Radiation Downward Flux
LWNT          Longwave Net Radiation Flux
NASA          National Aeronautics and Space Administration
PI            Principal Investigator
SRB           Surface Radiation Budget
SW            Shortwave Radiation
SWDN          Shortwave Radiation Downward Flux
SWNT          Shortwave Net Radiation Flux
TOA           Top-Of-Atmosphere
TONT          Total Net Radiation Flux