Lower ionosphere at middle latitudes: its morphology and response to meteorological and solar-terrestrial activity during the DYANA campaign 1990

Abstract

A large number of radio wave absorption, f{hook}min, and IPHA data measured in Europe and East Asia are investigated over the DYANA campaign period (1 January-31 March 1990) from the point of view of their response to meteorological and solar/geomagnetic forcing, of winter anomaly, and of a brief description of the state of the lower ionosphere on rocket salvo days. European mid-latitudinal measurements of electron density are briefly mentioned. The meteorological/solar control of the mid-latitudinal lower ionosphere during DYANA is considerably weaker than during MAP/WINE (winter 1983/84), but is evidently stronger than during MAP/SINE (summer 1987). The most distinct feature of the DYANA winter is a quite different response of the mid-latitudinal lower ionosphere to meteorological variability (namely to the 10 hPa North Pole temperature- indirect characteristics of a global state of the polar vortex) in the first and second halves of the DYANA period. The winter anomaly displays an expected magnitude and pattern during the DYANA winter. There is an expected weaker response of the lower ionosphere to the strong minor stratospheric warming of the first half of February. All three rocket salvos at Biscarosse (CEL) were carried out when the state of the lower ionosphere was within the range of normal (non-extremal) conditions. Various rocket salvos at Andoya took place on days of considerably different conditions in the lower ionosphere at higher mid-latitudes. Partial reflection measurements at Nizhny Novgorod show a clear tendency to a decrease of the electron density gradient between 70 and 80 km during March 1990. © 1994.