1] Sporadic E (E s ) can have dramatic effects on communications in the HF and low VHF range, producing over-the-horizon propagation for signals normally restricted to line-of-sight, and sometimes blocking F region propagation of signals in the lower HF range. Measuring the E region winds believed to produce E s is difficult, and no practical means of predicting E s occurrence currently exists other than statistical models. We describe a low-cost observing network based on software-controlled receivers that continuously watches for E s in near-real time using oblique HF propagation from existing transmitters. Results from an 11-day pilot campaign in July 2008 demonstrated that even a limited number of receivers in the network can readily determine the presence and extent of E s patches. These observations indicate that E s often develops quickly over regions of several hundred kilometers rather than gradually drifting across an area. These widespread E s "blooms" have been observed near winter solstice and occasionally at other times of the year; their lifetime depends on the season but can be several hours during the summer. The current network allows the extent of E s in portions of North America to be evaluated: the geographical distribution of E s and bounds on the density of the layer are inferred from its effects on the ionospheric maximum usable frequency (MUF). This study demonstrates quantitatively that E s mapping can provide information about E s layer geographical growth and decay. The observed sudden widespread E s blooms are space weather events that can have significant impact on HF/lower VHF communications and propagation model predictions.

[1] The outstanding problem faced by operational systems that utilize the ionosphere is that ionospheric weather variability is comparable to the ionospheric climate variability. However, the number of simultaneous measurements is orders of magnitude too few to resolve the weather scales that are impacting systems. We describe a prototype distributed array of affordable passive radio beacon monitors combined with a central data repository and a data-model analysis system called the Frequency-Agile Distributed Sensor System (FADSS). By monitoring signals from terrestrial VLF/HF radio beacons the FADSS tracks changes in the D, E, or F regions and makes appropriate modifications to the ionospheric specification in near real time. These observations provide fundamental seasonal and diurnal climatology and weather affecting the lower ionosphere. They demonstrate space weather effects on communications over the VLF through HF range, even during quiet solar minimum conditions.

This paper presents the design, construction, testing, and results of the project assigned to the 2014 NASA Langley Research Center Aeronautics Academy. The Academy was tasked with delivering one Unmanned Aerial System (UAS) capable of performing both Search and Rescue (SAR) and Precision Agriculture (PA) missions. The aircraft was constructed using primarily Commercial off-the-Shelf (COTS) electronics and flight hardware housed in a custom-fabricated airframe. The UAS, named TIGRESS (Technology in Ground Rescue and Environmental Stress Sensing) is capable of long-endurance autonomous flight, live video streaming, autonomous detections of persons, creation of Normalized Density Vegetation Index (NDVI) maps, and has completed four successful flights. The results of the flight tests, the design, and the construction methods are presented. Additionally, recommendations for further tests are presented.