U.S. scientists say 2011 was the ninth-warmest year on record in 33 years of satellite measurements of temperature readings for almost all regions of Earth.

This was despite La Nina Pacific Ocean cooling events at the start and finish of the year, John Christy, director of the Earth System Science Center at the University of Alabama in Huntsville, said.

Globally averaged, Earth's atmosphere was 0.27 degree Fahrenheit warmer in 2011 than the 30-year average, Christy, a professor of atmospheric science, said in a UA release Thursday.

As part of an ongoing project among the university, NASA and the National Oceanographic and Atmospheric Administration, Christy and his colleagues use data gathered by advanced microwave sounding units on NOAA and NASA satellites to get accurate temperature readings in almost all areas of Earth -- including remote deserts, oceans and rain forest areas where reliable climate data are not otherwise available.

The satellites measure the temperature of the atmosphere from the surface up to an altitude of about 26,000 feet above sea level.

The data are collected and processed monthly and made available to atmospheric scientists in the United States and abroad, the university release said.