Artificial ducts caused by HF heating of the ionosphere by HAARP

Abstract

[1] We report on satellite observations of plasma density enhancements (ducts) in the topside ionosphere during four HAARP/BRIOCHE campaigns during 2009-2010. Artificial ducts, caused by high-power HF radio wave injections from the HAARP transmitter toward the magnetic zenith, are detected by the DEMETER and DMSP satellites on a regular basis when there is a perceptible ionospheric F 2 peak density. Overall, the plasma density enhancements detected between 0930 and 1230 LT varied from 3-13%, while those during $1730-2215 LT were typically 15-40%. We also used a modified SAMI2 model to study the artificial ducts' mechanism driven by HF electron heating in the bottomside F 2 region. The heating builds up the plasma pressure, thus pushing plasma along the magnetic field. The simulation results performed for the input parameters similar to the conditions of the heating experiments are in fair agreement with the pertinent observations. The ducts seem to be produced most efficiently for heating frequencies quite close to the critical frequency f o F 2 .

Whistler propagation in ionospheric density ducts: Simulations and DEMETER observations

“…The model was generally found to be in agreement with observations, except that SAMI2 did not predict that "fine structure"-oscillations of the density about the expected mean with a scale length smaller than the width of the heating regionwould be present. Vartanyan et al [2012] has suggested that heating-driven enhancement of preexisting density irregularities could explain the formation of this fine structure. Ducts 1-3 likely represent fine structuring of the heating region due to the same process, as they are similar in both width and magnitude to the ducts previously identified by [Vartanyan et al 2012] under similar circumstances.…”

“…Vartanyan et al [2012] has suggested that heating-driven enhancement of preexisting density irregularities could explain the formation of this fine structure. Ducts 1-3 likely represent fine structuring of the heating region due to the same process, as they are similar in both width and magnitude to the ducts previously identified by [Vartanyan et al 2012] under similar circumstances.…”

“…[14] Vartanyan et al [2012] compared the density structure seen by DEMETER to the structure predicted by the SAMI2 ionospheric heating model. The model was generally found to be in agreement with observations, except that SAMI2 did not predict that "fine structure"-oscillations of the density about the expected mean with a scale length smaller than the width of the heating regionwould be present.…”

“…Such enhancements-called ducts-are known to occur naturally [Fejer and Kelley, 1980], but due in part to their ability to guide whistlers, there are ongoing efforts to produce these ducts artificially [e.g., Vartanyan et al, 2012].…”

A numerical study of large‐scale ionospheric modulation due to the thermal process by powerful wave heating

“…Since the diffusion coefficient is larger at the upper region than lower region, a duct of electron upflows formed at the topside ionosphere. This phenomenon has been observed by Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and DMSP satellites flying across the topside ionosphere of heating experiments [ Vartanyan et al ., ; Milikh et al ., , ]. Such pump‐induced plasma upwelling flow have also been detected by EISCAT during the Tromsø heating experiment and Sura heating facilities [ Rapoport et al ., , ; Frolov et al ., ; Kosch et al ., ].…”