摘要：The Planar Langmuir Probe onboard the Communication/Navigation Outage Forecasting System satellite monitored ionospheric plasma densities and their irregularities with high resolution almost seamlessly for approximately five years since May 2008. Planar Langmuir Probe data from two different years (1 October 2008 to 30 September 2009 and 5 June 2012 to 4 June 2013) were selected for analysis. The first data set corresponds to solar minimum conditions, and the second one is as close to solar maximum conditions of solar cycle 24 as possible, with basis on their continuous availability. The results from a level-crossing analysis applied to detrended evening-time data from a fixed altitude range show how depletion durations and spacings between consecutive depletions are statistically distributed as functions of solar activity and longitude sector. In quantitative terms, they show that (i) the fewer depletions observed in the solar-minimum year are also shorter, shallower, and closer together than those detected in the more active one and (ii) great similarities exist between structures of depletion durations and spacings between consecutive depletions observed in the South American and African longitude sectors, which are more noticeable than those associated with in the Indian-Asian longitude sector.
