U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-27 Monthly Average Polar Sea-Ice Concentration By Peter N. Schweitzer ANNOTATED LIST OF DIGITAL FILES Indented items reside in subdirectories ("folders" for Macintosh users). Names followed by the slash character ('/') are subdirectories. All text files are ASCII with lines terminated by carriage-return and line- feed characters, as is typical of MS-DOS systems. Users of Macintosh computers will see the line-feed characters as nonprinting symbols (little boxes), while users of UNIX systems will see the carriage returns as extraneous characters at the ends of the lines. The only exceptions are the text files in the directories Derived/unix/, which use line-feed characters only, and those in Derived/mac/, which use carriage-return characters only. Overall directory structure Contents/ Formal metadata and table of contents. Core/ Essential observations and data. meta/ Information essential for understanding the data. raw/ The data themselves. north/ Arctic region ice-concentration data. south/ Antarctic region ice-concentration data. Derived/ Useful but nonessential information, data, and tools. grids/ Ice concentration on 2-degree by 2-degree grids (tabular). images/ Ice concentration in popular digital image formats. gif/ Graphic Interchange Format (GIF) files. pict/ Macintosh PICT format (version 2). dos/ Software specifically for MS-DOS computers. mac/ Software specifically for Macintosh computers. unix/ Software specifically for UNIX computers. Detailed list of files A_README.1ST Summary information and instructions RUNME.BAT (MS-DOS) runs gsmenu DOSMENU/ gsmenu.exe MS-DOS text menu system gsmenu.doc Brief documentation of gsmenu sea_ice.mnu gsmenu configuration file moreinfo.mnu gsmenu configuration file ice_data.mnu gsmenu configuration file dos4gw.exe DOS extender used by see_ice.exe see_text.exe Text-file viewer for MS-DOS see_text/ Source code for see_text.exe see_text.doc Documentation for file viewer. see_text.c Source code for file viewer. doskeys.h Keystroke definitions. far_read.asm Like C fread but destination is far pointer. tscreen.asm Text-mode screen-handling-function source. tscreen.h Type declarations for functions in tscreen.asm. makefile Text indicating compiler options used. DOCFILES/ Text documents based on Core/meta/report.txt disclaim.doc Disclaimer. overview.doc Overview of the data set. authors.doc Authorship. acknowl.doc Acknowledgments. techinfo.doc System requirements. trouble.doc What to do if it doesn't work on DOS. getstart.doc Getting Started guide. referenc.doc References. contacts.doc Technical contacts. register.doc User registration. see_text.exe Text file viewer. Contents/ contents.txt Annotated list of digital files. mapsic.dif Formal metadata in NASA Directory Interchange Format. FGDCmeta.txt Formal metadata conforming to FGDC Content Standards for Digital Geospatial Metadata. Core/ meta/ report.txt Formal documentation of this publication. coverage Table showing days for which ice-concentration grids are available from NSIDC, including both SMMR data (1978 through 1987) and SSM/I data (1987 through 1991). Plain text. inv_smmr.txt Table showing inventory of SMMR data (1978-1987) inv_ssmi.txt Table showing inventory of SSM/I data (1987-1991) do_avgs (UNIX) Bourne shell script to build HDF data files containing the monthly averages and the composite monthly averages. northavg (UNIX) Makefile for creating averages of Northern Hemisphere data. southavg (UNIX) Makefile for creating averages of Southern Hemisphere data. do_imgs (UNIX) Bourne shell script to build images in GIF and PICT formats. do_topo (UNIX) Bourne shell script to create topographic data files consisting of elevation and bathymetry data from ETOPO5 registered on the same grid as is used by the sea-ice- concentration data. do_tabs (UNIX) Bourne shell script to create tab- delimited ASCII files representing composite monthly average sea-ice-concentration data on a rectangular grid whose cells measure 2 degrees of latitude by 2 degrees of longitude. src/ Makefile (UNIX) Makefile to build programs on a DG/UX system average.c Calculate monthly averages of sea-ice- concentration data. add_pal.c Add palette and annotation to HDF files. icetoppm.c Convert ice-concentration data in HDF format to portable pixmap. lltoxy.c Find the pixel coordinates corresponding to given geographic locations expressed as latitude and longitude. xytoll.c Find the geographic location corresponding to the given pixel coordinates. locate.c Routines to carry out polar stereographic map projection based on Clarke 1866 spheroid. makepltt.c Generate "pltt" palette resource for Macintosh. table.c Convert list to table for 2-degree by 2-degree grids. topo.c Sample ETOPO5 data using polar stereographic projection to create depth and elevation data for ice grids. depthppm.c Convert ETOPO5 data in polar projection to portable pixmap format. u_rtrv.c (UNIX and extended DOS) Retrieve ice concentration values for a series of data files at user-specified geographic locations. raw/ Essential observations and data files. north/ Monthly average sea-ice-concentration data and topography for the Arctic region. etopo5.n ETOPO5 elevation and bathymetry data for the Arctic region, sampled to conform to the polar stereographic projection in which the ice-concentration grids are arranged. Format: 16-bit binary image with big-endian byte ordering; there is a one-to-one correspondence of 16-bit words in this file with 8-bit data cells in the ice-concentration grids; the image is 304 pixels wide and 448 pixels high. 01n.hdf ... 12n.hdf Ensemble average of data from the years 1978 through 1991, using SSM/I data for July and August of 1987. Files are named according to the numbers of the months they represent, that is, 01n.hdf is the average of all data collected in January of any of the years 1979 through 1991, 02n.hdf represents February, etc. Format: 8-bit image, palette, and associated annotation arranged so as to be read by the Hierarchichal Data Format (HDF) Library, version 3.3r3, from the National Center for Supercomputing Applications (NCSA). This description applies to all files in the data set whose names end with the suffix ".hdf". avg_smmr/ Ensemble average of data from the years 1978 through 1987, using only data from the SMMR. smmr01n.hdf ... smmr12n.hdf avg_ssmi/ Ensemble averages of data from the years 1987 through 1991, using only data from the SSM/I. ssmi01n.hdf ... ssmi02n.hdf 1978/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1978. The sensor became operational on October 25, 1978; consequently only October, November, and December are represented here. %7810n.hdf 7811n.hdf 7812n.hdf Files are named according to the year and month they represent, that is, 7811n.hdf is the average of all images taken in November 1978. Because data collection began on the 25th of October 1978, 7810n.hdf is considered less representative of its time interval than are other such files, so its name is modified to emphasize the difference. The same convention was adopted for January 1988. 1979/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1979. 7901n.hdf ... 7912n.hdf 1980/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1980. 8001n.hdf ... 8012n.hdf 1981/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1981. 8101n.hdf ... 8112n.hdf 1982/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1982. 8201n.hdf ... 8212n.hdf 1983/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1983. 8301n.hdf ... 8312n.hdf 1984/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1984. 8401n.hdf ... 8412n.hdf 1985/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1985. 8501n.hdf ... 8512n.hdf 1986/ Monthly average sea-ice-concentration data for the Arctic region using SMMR data from 1986. 8601n.hdf ... 8612n.hdf 1987/ Monthly average sea-ice-concentration data for the Arctic region using SMMR and SSM/I data from 1987. 8701n.hdf ... 8706n.hdf SMMR 8707na.hdf SMMR 8708na.hdf SMMR 8707n.hdf SSM/I 8708n.hdf SSM/I 8709n.hdf ... 8711n.hdf SSM/I SMMR data are available from January 2 through August 20, and SSM/I data are available from July 9 through December 2. July and August of 1987 are the only two months during which both sensors were operational. Since the comparison of these images may be useful, data from the two sensors have been kept separate; the names of the files containing data from the SMMR were modified by adding the letter 'a' before the suffix. 1988/ Monthly average sea-ice-concentration data for the Arctic region using SSM/I data from 1988. %8801n.hdf 8802n.hdf ... 8812n.hdf 1989/ Monthly average sea-ice-concentration data for the Arctic region using SSM/I data from 1989. 8901n.hdf ... 8912n.hdf 1990/ Monthly average sea-ice-concentration data for the Arctic region using SSM/I data from 1990. 9001n.hdf ... 9012n.hdf 1991/ Monthly average sea-ice-concentration data for the Arctic region using SSM/I data from 1991. 9101n.hdf ... 9112n.hdf south/ Monthly average sea-ice-concentration data and topography for the Antarctic region. etopo5.s ETOPO5 elevation and bathymetry data for the Antarctic region, sampled to conform to the polar stereographic projection in which the ice-concentration grids are arranged. Format: same as etopo5.n, but 316 pixels wide and 332 high. 01s.hdf ... 12s.hdf Ensemble average of data from the years 1978 through 1991, using SSM/I data for July and August of 1987. avg_smmr/ Ensemble average of data from the years 1978 through 1987, using only data from the SMMR. smmr01s.hdf ... smmr12s.hdf avg_ssmi/ Ensemble averages of data from the years 1987 through 1991, using only data from the SSM/I. ssmi01s.hdf ... ssmi02s.hdf 1978/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1978. See notes for Core/raw/north/1978. %7810s.hdf 7811s.hdf 7812s.hdf 1979/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1979. 7901s.hdf ... 7912s.hdf 1980/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1980. 8001s.hdf ... 8012s.hdf 1981/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1981. 8101s.hdf ... 8112s.hdf 1982/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1982. 8201s.hdf ... 8212s.hdf 1983/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1983. 8301s.hdf ... 8312s.hdf 1984/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1984. 8401s.hdf ... 8412s.hdf 1985/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1985. 8501s.hdf ... 8512s.hdf 1986/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR data from 1986. 8601s.hdf ... 8612s.hdf 1987/ Monthly average sea-ice-concentration data for the Antarctic region using SMMR and SSM/I data from 1987. See notes for Core/raw/north/1987. 8701s.hdf ... 8706s.hdf SMMR 8707sa.hdf SMMR 8708sa.hdf SMMR 8707s.hdf SSM/I 8708s.hdf SSM/I 8709s.hdf ... 8711s.hdf SSM/I 1988/ Monthly average sea-ice-concentration data for the Antarctic region using SSM/I data from 1988. %8801s.hdf 8802s.hdf ... 8812s.hdf 1989/ Monthly average sea-ice-concentration data for the Antarctic region using SSM/I data from 1989. 8901s.hdf ... 8912s.hdf 1990/ Monthly average sea-ice-concentration data for the Antarctic region using SSM/I data from 1990. 9001s.hdf ... 9012s.hdf 1991/ Monthly average sea-ice-concentration data for the Antarctic region using SSM/I data from 1991. 9101s.hdf ... 9112s.hdf Derived/ dos/ Source code and executable versions of programs for extended DOS. makefile Automates building executables under MS-DOS. see_ice.exe (Executable) Graphical display tool. see_ice.c (Source code) Graphical display tool. read_ice.c Reads ice data from HDF file. searchup.c Searches up a directory tree for a file. locate.c Converts geographic and pixel coordinates. cursor.c Manages graphics cursor in super VGA modes. doskeys.h Associates names with BIOS key scan codes. hdftags.h Declarations of HDF tags, from HDF3.3r3. bios.asm Gets information from the BIOS data area. add1ice.asm Auxiliary routines for see_ice.c. keyboard.asm Gets keystroke data and keyboard status. mouse.asm Gets mouse motion and button presses. sound.asm Activates PC speaker. swabbers.asm Swaps bytes quickly on 386 systems. makefile Automates building software under MS-DOS. u_rtrv.lnk Watcom link editor command file for u_rtrv.c. see_ice.lnk Watcom link editor command file for see_ice.c. xytoll.lnk Watcom link editor command file for xytoll.c. lltoxy.lnk Watcom link editor command file for lltoxy.c. dos4gw.exe Rational Systems, Inc. DOS extender. lfl9x16.fon Font for use in high-resolution super VGA modes. lltoxy.exe Determines grid cell from geographic location. lltoxy.c Source code for lltoxy.exe. xytoll.exe Determines geographic location of grid cells. xytoll.c Source code for xytoll.exe. u_rtrv.exe Character-based data retrieval program. u_rtrv.c Source code for u_rtrv.exe. The following files are file lists used to determine what the graphical display tool see_ice.exe will show. n Arctic; ensemble averages. n.79 ... n.91 Arctic; monthly averages for each year. n.all Arctic; monthly averages. n.01 ... n.12 Arctic; each month but different years. s Antarctic; ensemble averages. s.79 ... s.91 Antarctic; monthly averages for each year. s.all Antarctic; monthly averages. s.01 ... s.12 Antarctic; each month but different years. mac/ Macintosh-specific files Files listed below with extension .hqx are binary files that have been converted to ASCII using BinHex 4.0. The conversion is necessary because UNIX and MS-DOS file systems have no convenient way to store the resource fork of a Macintosh file. These .hqx files are intended for those who have CD-ROM equipment connected to MS-DOS or UNIX computers but not to their Macintosh computers; simply copy the .hqx file to a diskette and copy the diskette to the Macintosh using Apple File Exchange. Run BinHex 4.0 to decode them. look_ice.hqx Nongraphical program to retrieve ice-concentration data at user-specified locations in the polar oceans. sea_ice.hqx Graphical program to retrieve and display ice- concentration data at user-specified locations in the polar oceans. Look up Ice/ (folder visible only on Macintosh) Look up Ice Executable program. source_code/ Look up ice.pi THINK C 6.0 project file. Look up ice.pi.Rsrc User interface resources. lookup_ice.c Main program and user interface code. UI_defines.h User interface resource identifiers. process_requests.c Manages retrieval of data. read_list_file.c Reads names of data files. read_request_file.c Reads geographic locations. request.h Request data structure definition. read_ice_file.c Reads HDF data files. hdftags.h Definitions of HDF tags. write_ice_output.c Writes results to disk. Sys7Avail.c Determines if system version is 7.x. find_file.c Locates a file by name. Mac_fileIO.c Simple file I/O routines for Macintosh. Mac_fileIO.h Function prototypes for Mac_fileIO.c. PtoCstrcpy.c Copies C strings to and from Pascal format. PtoCstrcpy.h Function prototypes for PtoCstrcpy.c. See Ice/ (folder visible only on Macintosh) See Ice Executable program. The following files are file lists used to determine what the graphical display tool See Ice will show. n Arctic; ensemble averages. n.79 ... n.91 Arctic; monthly averages for each year. n.all Arctic; monthly averages. n.01 ... n.12 Arctic; each month but different years. s Antarctic; ensemble averages. s.79 ... s.91 Antarctic; monthly averages for each year. s.all Antarctic; monthly averages. s.01 ... s.12 Antarctic; each month but different years. source_code/ See Ice.pi THINK C 6.0 project file. See Ice.pi.Rsrc User interface resources. SeeIce.c Main program and user interface code. SeeIce.h Data structure for ice-concentration. UI_defines.h User interface resource identifiers. hdftags.h Tag definitions for HDF files. read_list_file.c Reads names of data files. read_ice_file.c Reads ice data from HDF files. locate.c Converts pixel coordinates to geographic and vice versa. find_file.c Locates a file by name. Sys7Avail.c Determines if system version is 7.x. PtoCstrcpy.c Copies C strings to and from Pascal format. PtoCstrcpy.h Function prototypes for PtoCstrcpy.c. Mac_keysym.h Keystroke definitions for Macintosh. ice_pltt.r Rez code for the palette resource. clut.r Rez code for the color table resource. unix/ Source code of programs for the UNIX operating system with the X Window System. Makefile Automates building executable under DG/UX. see_ice.c Source code for graphical data retrieval program. see_ice.ico X bitmap for see_ice.c. searchup.c Searches up a directory tree for a file. locate.c Converts geographic and pixel coordinates. read_ice.c Reads ice data from HDF file. hdftags.h Defines tags for reading HDF files. The following files are file lists used to determine what the graphical display tool see_ice will show. n Arctic; ensemble averages. n.79 ... n.91 Arctic; monthly averages for each year. n.all Arctic; monthly averages. n.01 ... n.12 Arctic; each month but different years. s Antarctic; ensemble averages. s.79 ... s.91 Antarctic; monthly averages for each year. s.all Antarctic; monthly averages. s.01 ... s.12 Antarctic; each month but different years. grids/ 2-degree by 2-degree gridded modern average sea- ice data used as the basis for a model of sea-ice distribution during the Pliocene warm interval at 3.0 Ma. north/ grid_n.2x2 Geographic coordinates of grid cell centers; this file was used as input to u_rtrv. arctic.2x2 Monthly average ice-concentration data for each of the geographic locations given in grid_n.2x2; this file was output by u_rtrv. jan.tab Gridded ice-concentration data. The format of ... these files is tab-delimited text, where the dec.tab cell values correspond to ice-concentrations. south/ grid_s.2x2 Geographic coordinates of grid cell centers; this file was used as input to u_rtrv. antarct.2x2 Monthly average ice-concentration data for each of the geographic locations given in grid_s.2x2; this file was output by u_rtrv. jan.tab Gridded ice-concentration data. The format of ... these files is tab-delimited text, where the dec.tab cell values correspond to ice-concentrations. images/ Monthly average sea-ice-concentration data in formats suitable for display using software and hardware commonly found in microcomputers. gif/ Images formatted using Graphic Interchange Format (GIF), a trademark of CompuServe Inc. The files whose names end with the suffix ".gif" were produced by applying the program icetoppm.c to the HDF data file that has the same name. The resulting portable pixmap was converted to GIF using the ppmtogif program of the PbmPlus toolkit. north/ GIF images of the Arctic region. etopo5n.gif Topography. This file was produced using the program depthppm.c with the file etopo5.n as the input data. 01n.gif ... 12n.gif Ensemble averages of ice concentration. (SMMR and SSM/I) 1978/ Ice concentration for 1978. %7810n.gif (SMMR) 7811n.gif (SMMR) 7812n.gif (SMMR) 1979/ Ice concentration for 1979. 7901n.gif ... 7912n.gif (SMMR) 1980/ Ice concentration for 1980. 8001n.gif ... 8012n.gif (SMMR) 1981/ Ice concentration for 1981. 8101n.gif ... 8112n.gif (SMMR) 1982/ Ice concentration for 1982. 8201n.gif ... 8212n.gif (SMMR) 1983/ Ice concentration for 1983. 8301n.gif ... 8312n.gif (SMMR) 1984/ Ice concentration for 1984. 8401n.gif ... 8412n.gif (SMMR) 1985/ Ice concentration for 1985. 8501n.gif ... 8512n.gif (SMMR) 1986/ Ice concentration for 1986. 8601n.gif ... 8612n.gif (SMMR) 1987/ Ice concentration for 1987. 8701n.gif ... 8706n.gif (SMMR) 8707na.gif (SMMR) 8708na.gif (SMMR) 8707n.gif (SSM/I) 8708n.gif (SSM/I) 8709n.gif ... 8711n.gif (SSM/I) 1988/ Ice concentration for 1988. %8801n.gif (SSM/I) 8802n.gif ... 8812n.gif (SSM/I) 1989/ Ice concentration for 1989. 8901n.gif ... 8912n.gif (SSM/I) 1990/ Ice concentration for 1990. 9001n.gif ... 9012n.gif (SSM/I) 1991/ Ice concentration for 1991. 9101n.gif ... 9112n.gif (SSM/I) south/ GIF images of the Antarctic region. etopo5s.gif Topography. This file was produced using the program depthppm.c with the file etopo5.s as the input data. 01s.gif ... 12s.gif Ensemble averages of ice concentration. (SMMR and SSM/I) 1978/ Ice concentration for 1978. %7810s.gif (SMMR) 7811s.gif (SMMR) 7812s.gif (SMMR) 1979/ Ice concentration for 1979. 7901s.gif ... 7912s.gif (SMMR) 1980/ Ice concentration for 1980. 8001s.gif ... 8012s.gif (SMMR) 1981/ Ice concentration for 1981. 8101s.gif ... 8112s.gif (SMMR) 1982/ Ice concentration for 1982. 8201s.gif ... 8212s.gif (SMMR) 1983/ Ice concentration for 1983. 8301s.gif ... 8312s.gif (SMMR) 1984/ Ice concentration for 1984. 8401s.gif ... 8412s.gif (SMMR) 1985/ Ice concentration for 1985. 8501s.gif ... 8512s.gif (SMMR) 1986/ Ice concentration for 1986. 8601s.gif ... 8612s.gif (SMMR) 1987/ Ice concentration for 1987. 8701s.gif ... 8706s.gif (SMMR) 8707sa.gif (SMMR) 8708sa.gif (SMMR) 8707s.gif (SSM/I) 8708s.gif (SSM/I) 8709s.gif ... 8711s.gif (SSM/I) 1988/ Ice concentration for 1988. %8801s.gif (SSM/I) 8802s.gif ... 8812s.gif (SSM/I) 1989/ Ice concentration for 1989. 8901s.gif ... 8912s.gif (SSM/I) 1990/ Ice concentration for 1990. 9001s.gif ... 9012s.gif (SSM/I) 1991/ Ice concentration for 1991. 9101s.gif ... 9112s.gif (SSM/I) pict/ Images stored in the Macintosh PICT2 format defined by Apple Computer, Inc. The files whose names end with the suffix ".pict" were produced by applying the program icetoppm.c to the HDF data file that has the same name. The resulting portable pixmap was converted to PICT format using the ppmtopict program of the PbmPlus toolkit. north/ PICT images of the Arctic region. etopo5n.pict Topography. This file was produced using the program depthppm.c with the file etopo5.n as the input data. 01n.pict ... 12n.pict Ensemble averages of ice concentration. (SMMR and SSM/I) 1978/ Ice concentration for 1978. %7810n.pict (SMMR) 7811n.pict (SMMR) 7812n.pict (SMMR) 1979/ Ice concentration for 1979. 7901n.pict ... 7912n.pict (SMMR) 1980/ Ice concentration for 1980. 8001n.pict ... 8012n.pict (SMMR) 1981/ Ice concentration for 1981. 8101n.pict ... 8112n.pict (SMMR) 1982/ Ice concentration for 1982. 8201n.pict ... 8212n.pict (SMMR) 1983/ Ice concentration for 1983. 8301n.pict ... 8312n.pict (SMMR) 1984/ Ice concentration for 1984. 8401n.pict ... 8412n.pict (SMMR) 1985/ Ice concentration for 1985. 8501n.pict ... 8512n.pict (SMMR) 1986/ Ice concentration for 1986. 8601n.pict ... 8612n.pict (SMMR) 1987/ Ice concentration for 1987. 8701n.pict ... 8706n.pict (SMMR) 8707na.pict (SMMR) 8708na.pict (SMMR) 8707n.pict (SSM/I) 8708n.pict (SSM/I) 8709n.pict ... 8711n.pict (SSM/I) 1988/ Ice concentration for 1988. %8801n.pict (SSM/I) 8802n.pict ... 8812n.pict (SSM/I) 1989/ Ice concentration for 1989. 8901n.pict ... 8912n.pict (SSM/I) 1990/ Ice concentration for 1990. 9001n.pict ... 9012n.pict (SSM/I) 1991/ Ice concentration for 1991. 9101n.pict ... 9112n.pict (SSM/I) south/ PICT images of the Antarctic region. etopo5s.pict Topography. This file was produced using the program depthppm.c with the file etopo5.s as the input data. 01s.pict ... 12s.pict Ensemble averages of ice concentration. (SMMR and SSM/I) 1978/ Ice concentration for 1978. %7810s.pict (SMMR) 7811s.pict (SMMR) 7812s.pict (SMMR) 1979/ Ice concentration for 1979. 7901s.pict ... 7912s.pict (SMMR) 1980/ Ice concentration for 1980. 8001s.pict ... 8012s.pict (SMMR) 1981/ Ice concentration for 1981. 8101s.pict ... 8112s.pict (SMMR) 1982/ Ice concentration for 1982. 8201s.pict ... 8212s.pict (SMMR) 1983/ Ice concentration for 1983. 8301s.pict ... 8312s.pict (SMMR) 1984/ Ice concentration for 1984. 8401s.pict ... 8412s.pict (SMMR) 1985/ Ice concentration for 1985. 8501s.pict ... 8512s.pict (SMMR) 1986/ Ice concentration for 1986. 8601s.pict ... 8612s.pict (SMMR) 1987/ Ice concentration for 1987. 8701s.pict ... 8706s.pict (SMMR) 8707sa.pict (SMMR) 8708sa.pict (SMMR) 8707s.pict (SSM/I) 8708s.pict (SSM/I) 8709s.pict ... 8711s.pict (SSM/I) 1988/ Ice concentration for 1988. %8801s.pict (SSM/I) 8802s.pict ... 8812s.pict (SSM/I) 1989/ Ice concentration for 1989. 8901s.pict ... 8912s.pict (SSM/I) 1990/ Ice concentration for 1990. 9001s.pict ... 9012s.pict (SSM/I) 1991/ Ice concentration for 1991. 9101s.pict ... 9112s.pict (SSM/I) (end)