In a recent study by PhD student Xiangchai Chen PhD Student at BCSS Xiangcai Chenat the Birkeland Centre for Space Science and colleagues from China, an extensive survey of the dayside diffuse aurora has been conducted. Now their paper has been published in the Journal of Geophysical Research, and the Editor decided to highlight one of their figures on the front page because of its scientific significance.
Chen and his colleagues have studied dayside diffuse aurora. By analyzing 7 years of all-sky camera data at 557.7 nm from the Chinese Yellow River Station in Ny-Ålesund in Svalbard under relatively quiet geomagnetic conditions (i.e. when the auroral oval is contracted far north of Svalbard and it is possible to observe the diffuse aurora), they were able to characterize the discrete aurora.
In the figure below highlighted on the front page of JGR, the authors summarize their findings in a conceptual sketch. The morning diffuse aurora is produced by scattering of hot electrons from the plasma sheet, while in the afternoon diffuse aurora is produced by scattering of hot ions from the plasma sheet. The east-west and north-south alignment of the discrete aurora is found to vary with magnetic local time. At magnetic noon a new type of diffuse aurora is observed and called throat aurora. It is aligned with the plasma convection seen by SuperDARN, and the authors speculate that it could be related to either ionospheric outflow or plasmaspheric drainage plumes. As the first very detailed study of the dayside diffuse auroras this paper is indeed a significant result!
The paper entitled "An extensive survey of dayside diffuse aurora based on optical observations at Yellow River Station" may be found here.