| Popis: |
A comprehensive statistical study of Spread F using digisonde data from low and midlatitude global sites has been conducted. Data from five midlatitude stations in the north-American include: Ramey AFB, Puerto Rico (18.5°N, 67.1°W, -14° declination angle) for 1996-2011, Wallops Island, Virginia (37.95°N, 75.5°W, -11° declination angle) for 1996-2011, Dyess, Texas (32.4°N, 99.8°W, 6.9° decl. angle) for 1996-2009, Boulder, Colorado (40°N, 105.3°W, 10° decl. angle) for 2004-2011, and Vandenberg AFB, California (34.8°N,120.5°W, 13° decl. angle) for 1996-2009. Low-latitude stations include: Ascension Island (7.9°S, 14.4°W, -15.09° decl. angle) from 2000-2014, Kwajalein (8.71°N, 167.7°E, 7.5° decl. angle) from 2004-2012. Multiple algorithms have been written to process the raw data and determine spread F by using edge detection and pattern recognition techniques. Pattern recognition algorithms are used to determine the presence of both range and frequency spread F. Algorithms have also been written to find foF2 and hmF2 values for obtaining the density profile of the ionosphere. Vertical Incidence Pulsed Ionospheric Radar (VIPIR) data was also processed for a few of these sites for determining the foF2 values and the comparison between the two instruments. Findings based on work carried out to date include: • Determination of seasonal and solar cycle variation patterns. • Correlation between digisonde, COSMIC-1/FORMOSAT-3 satellite data and SAMI and IRI models values to check for validity of data. • Wave analysis has been performed to detect the presence of planetary and gravity wave type patterns in foF2 values with periods ranging from a few hours to a few days and for various seasons. |
