Significant upper thermospheric contribution to the O(1S) 557.7 nm dayglow emission - First ground based evidence

Out of the two source regions of O(1S) green line 557.7-nm emission, namely, the one in the lower thermosphere and the other in the upper thermosphere, the upper thermospheric source is known to contribute only 15-20 percent of the total 557.7-nm volume emission during nighttime. On the other hand, successful simultaneous ground-based measurements of daytime 557.7-nm O(1S) and 630.0 nm O(1D) thermospheric emissions with the multiwavelength daytime photometer (MWDPM) reveal striking similarities in their variabilities, the inference being the dominance of thermospheric contribution in 557.7-nm O(1S) emission throughout the day, in conformity with the spaceborne measurements made elsewhere. The first set of ground-based measurements is presented and discussed. (Author)