Two American scientists, one of them an expert on the greenhouse effect, will receive $400,000 each as the 1989 recipients of the Japan Prize in Medicine and Environmental Science and Technology, the organizers announced Wednesday.

The Science and Technology Foundation of Japan said its Prize for Environmental Science and Technology will be awarded to Frank Sherwood Rowland, a professor of chemistry at the University of California at Irvine who theorized in 1974 that chlorofluorocarbons were depleting the earth's protective ozone layer. The Medicinal Science Prize will be awarded to Elias James Corey, a pioneer in organic chemistry at Harvard University, the foundation said.Each man will receive $400,000.

The Japan Prize, which the founders hope will some day have a stature on par with the Nobel Prize, has been awarded annually since 1983 for remarkable achievements in science and technology. Americans have won nine of the 15 prizes.