The Outgoing Long-wave Radiation（ OLR） derived from the FY-3A /VIRR and NOAA19 /AVHRR satellites indicated the presence of some errors. To satisfy the needs of the operational and scientific studies

it was necessary to analyze the similarity and differences in the FY-3A / VIRR-OLR and the OLR derived from other satellites. Using the daily average OLR of FY-3A / VIRR as the test data

the daily average OLR of NOAA18 / AVHRR as the test source data

and using the methods to determine the correlation coefficient

deviation

root mean square error（ RMSE）

and relative error

the similarity and differences of the daily average OLR of the satellites FY-3A / VIRR and NOAA18 / AVHRR were analyzed. The results showed that the correlation coefficient was large and the deviation

RMSE and relative error were small for the majority of the two sets of data. However

the correlation coefficient was small

and the deviation

RMSE and relative error were large for a small proportion of the two sets of data. For example

on April 23

July 13

and October 13

2010

the correlation coefficient was 0. 63

0. 5

and 0. 3

respectively; the deviation was 7 Wm- 2

-5 Wm- 2

and-200 Wm- 2

respectively; the RMSE was 31

45

and 225 Wm- 2

respectively; and the relative error was 0. 12

0. 125

and 0. 85

respectively. The difference occurred mainly in the mountains and the tropical oceans

and the difference was larger in the warm season than in the cold season. The difference in the two sets of data may have also been caused by the stronger convective flow in the mountains and tropical oceans in the warm season. Because the FY-3A Satellite acquired the data in the morning and the NOAA18 Satellite acquired the data in the afternoon

there were different orbiting periods

which may have led to differences for the two sets of data.