Coherent Radio Beacon Experiment (CRABEX)
The Indian Coherent Radio Beacon Experiment (CRABEX) was initiated mainly to address the questions regarding the large-scale processes over equatorial and low latitudes. This experiment consists of five radio receivers stationed at Trivandrum (8.5deg.N, 77deg.E), Bangalore (13deg.N, 77.6deg.E), Hyderabad (17.3deg.N, 78.3deg.E), Bhopal (23.2deg. N, 77.2deg.E), and Delhi (28.8deg.N, 77.2deg.E) that are capable of receiving the 150 and 400 MHz beacon transmissions from the Low Earth Orbiting Satellites (LEOS). This chain is unique as it covers the crest and trough regions of the EIA latitudinally, and goes well beyond the anomaly crest. Thus, the data obtained using this chain will help in understanding the temporal and spatial evolution of equatorial and low-latitude ionospheric phenomena like EIA and ESF, and their interrelationships. For example, the degree of variability of the EIA, which is otherwise quite difficult to be monitored completely, can be understood by the tomographic methods. The maximum E X B drift, the location of the EIA crest and its intensity which are known to be intricately connected to the generation of equatorial bubbles, as well as bottomside spread F, are investigated in detail using the tomograms.