year mo    data_type region extent   area
1979  9      Goddard      N   7.20   4.53
1980  9      Goddard      N   7.85   4.83
1981  9      Goddard      N   7.25   4.38
1982  9      Goddard      N   7.45   4.38
1983  9      Goddard      N   7.52   4.64
1984  9      Goddard      N   7.17   4.05
1985  9      Goddard      N   6.93   4.17
1986  9      Goddard      N   7.54   4.66
1987  9      Goddard      N   7.48   5.60
1988  9      Goddard      N   7.49   5.31
1989  9      Goddard      N   7.04   4.81
1990  9      Goddard      N   6.24   4.50
1991  9      Goddard      N   6.55   4.46
1992  9      Goddard      N   7.55   5.37
1993  9      Goddard      N   6.50   4.52
1994  9      Goddard      N   7.18   5.08
1995  9      Goddard      N   6.13   4.38
1996  9      Goddard      N   7.88   5.58
1997  9      Goddard      N   6.74   4.84
1998  9      Goddard      N   6.56   4.24
1999  9      Goddard      N   6.24   4.22
2000  9      Goddard      N   6.32   4.31
2001  9      Goddard      N   6.75   4.55
2002  9      Goddard      N   5.96   3.98
2003  9      Goddard      N   6.15   4.01
2004  9      Goddard      N   6.05   4.35
2005  9      Goddard      N   5.57   4.03
2006  9      Goddard      N   5.92   3.97
2007  9      Goddard      N   4.30   2.78
2008  9       PRELIM      N   4.68   2.93
2009  9      NRTSI-G      N   5.36   3.42
2010  9      NRTSI-G      N   4.90   3.02

 Important Note: The "extent" column includes the area near the pole not
 imaged by the sensor. It is assumed to be entirely ice covered with at
 least 15% concentration. However, the "area" column excludes the area not
 imaged by the sensor. This area is 1.19 million square kilometers for SMMR
 (from the beginning of the series through June 1987) and 0.31 million
 square kilometers for SSM/I (from July 1987 to present). Therefore, there
 is a discontinuity in the "area" data values in this file at the June/July
 1987 boundary.