1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, and 1999. International Heat Flow Commission, International Association of Seismology and Physics of the Earth's Interior, and Oklahoma State University. Department of Geography. Cartography Service. This point shapefile contains heat flow data for Niger compiled from sources dating from 1979 to 1999. Heat flow is a measure of heat loss across t... International Heat Flow Commission.