This document provides a general description of the SHEBA snow and ice program, 
as well as data and metadata. This work was done cooperatively by researchers 
at the U.S. Army Cold Regions Research and Engineering Laboratory (Don Perovich, 
Jackie Richter-Menge, Matthew Sturm, Terry Tucker, Bruce Elder, Bill Bosworth, 
John Govoni, Kerry Claffey, and Roy Belyea), the University of Washington 
(Tom Grenfell, Gary Maykut, and Bonnie Light), the University of Alaska 
(Hajo Eicken) and the Japanese Frontier Program (Jinro Ukita) 
  
The overall objective of the SHEBA snow and ice program is to develop a 
quantitative understanding of the processes that collectively make up 
the ice-albedo feedback mechanism. To achieve this objective, we must 
first determine how shortwave radiation is distributed within the ice-ocean 
system, then assess the effects of this distribution on the regional heat 
and mass balance of the ice pack. Complicating the problem are a variety of 
issues related to the extreme sub-grid scale variability of the ice pack and 
how it can be accounted for in large-scale climate models and GCMs. There are 
3 broad considerations that motivated our study: 

· How is shortwave radiation partitioned between reflection, surface melting, 
    internal heat storage, and transmission to the ocean, and how is this 
    partitioning affected by the physical properties of the ice, snow cover, 
    melt ponds and the distribution of particulates? 
· What is the areal distribution of ice, ponds, and leads, how does this 
    distribution vary with time, and how does it affect area-averaged heat and mass fluxes? 
· What are the crucial variables needed to characterize ice-albedo feedback processes and 
    their effect on the heat and mass balance of the ice pack, and how accurately can they 
    be treated through simplified models and parameterizations?

 The many distinct facets of the snow and ice program can be group into five general categories:
    Optics: measurements of albedo, transmittance, and incident ultraviolet irradiance.
    Mass balance: 9 sites with thermistor strings, 120 thickness gauge/ablation stake , 
        plus pond and ridge evolution.
    Snow: spatial evolution and spatial variability of snow depth along 4 lines.
    Aerial observations: aerial photographs plus surface temperature measurements from 12 
        helicopter survey flights.
    Ancillary: this includes observations of ice internal stress, ice physical properties, 
        ice permeability, ice topography, and soot.
    Logs: bridge logs, ice team logs, and fun stuff from SHEBA   

Snow and ice measurements were made throughout the entire SHEBA year. Depending on the time 
of year the ice program had as few as one person and as many as five at Ice Station SHEBA. 
Most of our measurements were made within a few kilometers of the ship.
 
There are snow and ice datafiles in the directory ICEDATA. 
This main directory has five primary subdirectories where data and metadata 
are stored. The directories, along with a thumbnail description of their 
contents are listed below.

* AERIAL - data relating to helicopter survey and photography flights
       * Heloalb - helicopter based albedo measurements
       * KT19 - helicopter based surface temperature measurements
* MASS - data relating to mass balance studies
       * EM -  electromagnetic induction surveys of ice thickness
       * Gauge - year-long data from 135 thickness gauge/ablation stake combinations
       * Pond - observations of melt pond areal extent, depth, temperature, and salinity
       * Temper - time series of ice temperature from thermistor strings at 8 sites
       * Waterlev - results from waterlevel recorders at Quebec and the Doghouse
* OPTICS - optical measurements of albedo and transmittance 
       * In_ice - in ice profiles of upwelling and downwelling spectral irradiance at selected sites
       * Specalb - spatial and temporal variability of spectral albedo from 300 nm to 2000 nm 
       * Totalb -  spatial and temporal variability of wavelength-integrated albedo
       * Trans -  transmitted spectral irradiance at selected sites
* SNOW - snow observations 
       * Snowsurv - surveys of snow depth conducted along four lines during the SHEBA year
       * SnowIOP - observations made during a snow Intensive Observation Period in Spring 1998
* ANCILL - ancillary snow and ice measurements made during SHEBA
       * Icecores - ice physical properties measured for selected cores
       * Perm - ice permeability observations for selected sites
       * Sal - ice salinity and O18 observations
       * Soot - observations of soot levels at SHEBA
       * Stress - measurements of internal ice stress at 8 sites through the SHEBA year
       * Topo - surface topography observations made during spring and summer


Acknowledgments: We thank the crew of the Des Groseilliers, the SHEBA logistics office, and 
the SHEBA project office for their help during the field experiment. This work has been funded 
by the National Science Foundation Arctic System Science Program and the Office of Naval 
Research High Latitude Program. 


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*                           F R E E    I C E   D A T A    C D - R O M                     *
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* Great news! You can get all of these data, plus a browser based explanation on a CD-ROM *
*                     Contact Don Perovich:  perovich@crrel.usace.army.mil                *
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