Two types of positive disturbances in the daytime mid-latitude F2-layer: Morphology and formation mechanisms

摘要: Abstract Morphological analysis of foF2 variations for the periods daytime positive disturbances over three ionospheric stations St. Petersburg (sub-auroral zone), Slough (middle latitudes), and Alma-Ata (middle-low latitudes) has confirmed existence two types F2-layer with different morphology. Type I is referred to those followed by quiet or positively disturbed conditions. They occur under low moderate level geomagnetic activity. Positive type II are related strong storms they negative disturbances. The manifest occurrence frequency distribution its dependence on latitude also exhibit duration magnitude. This tells that belong classes events may have formation mechanisms. Millstone Hill ISR digisonde hmF2 observations some selected both were analyzed. original earlier developed self-consistent method extract thermospheric parameters from was used estimate contribution various aeronomic observed storm time variations. Our a well-pronounced December 14, 2006 well-known concept Prolss, 1993a , 1993b 1995 —daytime midlatitude mainly produced TADs following them equatorward winds. However our calculations shown about half effect be attributed parameter (neutral composition temperature) presents first phase two-phase (positive/negative) storm. For this reason their similar driving force same—the thermosphere heating in auroral zone. Situation more complicated. Electric fields April 03, 2004, neutral (mainly atomic oxygen) 11, 2000 responsible effect. difference cases presumably localization (longitudinal sector) heating.