Twelve month running trends from Earth Radiation Budget Satellite (ERBS) active cavity radiometric measurements and global surface temperatures

摘要

Four earth-viewing nonscanning active cavity radiometers of the ERBS (Earth Radiation Budget Satellite) have been measuring the radiation arising from the earth-atmosphere system since its' launch day, October 5, 1984. The ERBS spacecraft was placed in a non-sun-synchronous trajectory inclined at 57°. Two radiometers out of four, namely the wide field-of-view total (WFOV-T) radiometer which measures the radiation in the total spectral band of 0.2 - 100 μm, and the wide-field-of-view shortwave (WFOV-SW) radiometer measures the Earth's reflected radiation in the wavelength region of 0.2 - 5μm were used in this study. These sensors were calibrated continuously by observing the in-flight internal black bodies as well as the Sun every two weeks. The WFOV-T channel was found very stable within 0.1%~1. The monthly flux values of the ERBS nonscanning active cavity radiometers at satellite altitude and the corresponding NCDC (National Climatic Data Center) global surface temperature data for the period of fifteen years (1985-1999) were used in this paper. The effect of Mt. Pinatubo eruption is very clearly noticeable in the running trends of both WFOV-T and WFOV-SW radiometric measurements. Further, the resulting twelve month running trends derived from the outgoing longwave radiation was found to follow the twelve month running trend determined from the global surface temperature data set. Both trends are real and increasing. The "global-cooling-like" event caused by the Mt. Pinatubo eruption was also found under both day and nighttime conditions.