Global examination of the relationship between nitirc oxide and solar variability

• Other Authors: Reynolds, Amber (author), Marsh, Daniel (contributor), Barth, Mary (contributor), Mangan, Jennifer (contributor), Noble, Erik (contributor)
• Format: Manuscript
• Language: English
• Published: 2002
• Subjects: Thermosphere; Stratosphere; Ozone; Solar energy; Solar cycle; polar night
• Online Access: http://nldr.library.ucar.edu/repository/collections/SOARS-000-000-000-129; https://doi.org/10.5065/eyrw-n594

Nitric oxide (NO), which is produced in the thermosphere as well as in other layers of the atmosphere, is known to destroy stratospheric ozone. Production of NO in the thermosphere is proportional to the amount of available solar energy, which fluctuates due to long-term variability such as the 11-year solar cycle and short-term variability such as solar storms, flare, etc. This research has performed a global examination of the relationship between production of NO in the thermosphere and solar variability by using data collected by the Student Nitric Oxide Explorer (SNOE). To quantify the correlation between production of NO in the thermosphere and solar variability, Empirical Orthogonal Functions (EOF) are used to compare variability in the monthly average of NO concentration observed by SNOE with two proxies for solar activity (F10.7 and Kp index). EOF analysis has revealed that the dominant mode of variability is seasonal, related to the absence of NO loss through photolysis during polar night. The second mode of variability appears to be well correlated to the highly variable Kp index, indication that increased auroral activity will result in increased levels of NO in high latitudes. Finally, in the tropics the third mode is well correlated to the F10.7 index, and confirms that long-term changes in solar radiation are directly related to tropical production of NO. The results of this research have provided an empirical database of thermospheric NO, suitable for inclusion in upper-atmospheric models, that includes the effects of solar fluctuations.