COORDINATED ROCKET MEASUREMENTS ON D-REGION WINTER ANOMALY .I. EXPERIMENTAL RESULTS

Because of possible associations between D-region warmings and enhanced electron densities on winter days of high radio-wave absorption, nearly simultaneous rocket measurements of D-region temperatures and electron densities were conducted on an anomalous winter day at Wallops Island, Virginia. Groundbased radio-wave absorption measurements on 3.03 MHz and sweep-frequency ionosonde observations revealed that 31 January 1967 was an anomalous winter day, and rockets were launched to measure electron densities, neutral temperatures, and winds in the D-region. On 3 February 1967, the 3.03 MHz radio wave absorption had decreased to normal levels and a second rocket-grenade experiment was launched to measure neutral temperatures and winds in the mesosphere. The electron density profile for 31 January 1967 was generally similar to the one measured on the anomalous winter day of 10 January 1966, the densities in the 70-80 km height range being about five times greater than those on a normal winter day. The rocket-grenade temperature profile for the anomalous day revealed a strong temperature inversion at 70 km and a warm layer extending from the inversion to 84 km; this temperature structure was significantly different from that at the same altitudes on the normal day of 3 February 1967. © 1969.