Cusp-latitude conjugate ionospheric absorption associated with increase of solar wind dynamic pressure during strong northward IMF : a case study

Conjugate ionospheric absorption was observed in the magnetic pre-noon by the inter-hemispheric imaging riometers (IRISs) at Ny-Aelesund (NAL), Svalbard and Zhongshan (ZHS), Antarctica in the cusp-latitude. The absorption was associated with increase of solar wind dynamic pressure during the strong northward interplanetary magnetic field. The conjugate absorption features showed a sequence of spike-shape with intensity of 400 km) exceeding the IRIS field-of-view with a poleward motion. The absorption spikes at NAL preceded the ones at ZHS by about 4 min. The absorption at NAL was located at part of enhanced auroral luminosity in the main oval from the POLAR UVI images, and also near the lower-latitude convection reversal in the plasma convection cell from the SuperDARN radar network of the northern hemisphere. Conjugate relationships, electrodynamics of electron precipitation and possible absorption mechanisms are discussed from these characteristics.