The observed OSSs can be related to the equatorial/low-latitude spread F and roughly eastward propagation in both Tucumán and Taiwan.
At either station, MSTIDs occurrence is found to depend on season and solar cycle, that is, lower during equinoctial seasons and low solar activity, in accordance with the general morphological features of mid-latitude spread F (MSF).
Moreover, equatorial and low-latitude spread F is often associated with plasma bubbles and scintillations of global positioning system (GPS) signals (Chen et al. 2006; Shi et al. 2011; Alfonsi et al. 2013), which may cause inaccuracies in position determination.
The occurrence of mid-latitude spread F (SF) over South Africa has not been extensively studied since the installation of the DPS-4 digisondes in 1996 and 2000 at Grahamstown (33.32 °S, 26.50 °E) and Madimbo (22.38 °S, 30.88 °E) respectively.
The data show that debris from two 2006 tropical eruptions managed to spread globally through the stratosphere, while two eruptions in 2008 and 2009 at higher, northern latitudes spread through much of the Northern Hemisphere's stratosphere.
Ms. Collins has already begun work with Senator Mark Udall, Democrat of Colorado, on legislation to mitigate the impact of the across-the-board sequester cuts by giving the Obama administration more latitude to spread them around.
Ms. Collins has already begun work with Senator Mark Udall, Democrat of Colorado, on legislation to mitigate the impact of the across-the-board cuts by giving the Obama administration more latitude to spread them around.
Dabas et al. (1998, 2003) observed the occurrence of VHF scintillation at low latitudes and spread F activity in equatorial regions.
However, on the basis of minimum in H occurred near midnight at the same UT at all the five stations almost in the same latitude range but spread over a longitude range of ~115°, Mizzi and Schlapp (1971) suggests that the probable cause of these AQDs event might be extra-terrestrial in origin.
These global maps show that dust injected from certain areas in the northern mid-latitudes tends to spread widely within a few days.
