Dr. Hanson of NOAA said today that the new study does not in any way contradict the findings reported by the NASA scientists and others. He said that his study, in which he was joined by George A. Maul and Thomas A. Karl, also of NOAA, looked at only the 48 contiguous states.

Dr. Hanson said that global warming caused by the greenhouse effect might have been countered by some cooling phenomenon that has not yet been identified and that the readings in his study recorded the net effect.

''We have to be careful about interpreting things like this,'' he said. What About Urbanization? One aspect of the study that Dr. Hanson said was interesting was the finding that the urbanization of the United States has apparently not had a statistically significant effect on average temperature readings. A number of scientists have theorized that the replacement of forests and pastures by asphalt streets and concrete buildings, which retain heat, is an important cause of rising temperatures.

Dr. Hansen of NASA said today that he had ''no quarrel'' with the findings in the new study. He noted that the United States covered only 1.5 percent of Earth. ''If you have only one degree warming on a global average, how much do you get at random'' when taking measurements in such a relatively small area, he asked rhetorically.

''We are just arguing now about whether the global warming effect is large enough to see,'' he added. ''It is not suprising we are not seeing it in a region that covers only 1.5 percent of the globe.''

Dr. Hansen said there were several ways to look at the temperature readings for the United States, including as a ''statistical fluke.'' Possibililty of Countereffects

Another possibility, he said, was that there were special conditions in the United States that would tend to offset a warming trend. For example, industrial activity produces dust and other solid particles that help form liquid droplets in the atmosphere. These droplets reflect radiation away from Earth and thus have a cooling influence.