HAO 2012 Profiles In Science: Dr. Liying Qian

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Dr. Liying Qian received her Ph. D. in Meteorology and M.E. in Computer Sciences and Engineering from the Pennsylvania State University, her B.S. in Atmospheric Sciences from Nanjing University, China, and her M.S. in Atmospheric Sciences from Chinese Academy of Science, China. Dr. Qian studies space weather impact on the thermosphere and ionosphere, long-term changes in the upper atmosphere due to greenhouse gases, and vertical coupling between the lower atmosphere and the upper atmosphere. She has extensive experience in numerical modeling, including the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM), and the Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM).

Publications

Figure 1: High resolution

(1) Qian, L., A. G. Burns, H. Liu, and P. C. Chamberlin. 2012: Effect of a solar flare on a traveling atmospheric disturbance, J. Geophys. Res., 117, A10319, doi:10.1029/2012JA017806.

Abstract: It is known that the sudden injection of energy during geomagnetic storms can excite atmospheric gravity waves (AGWs) or traveling atmospheric disturbances (TADs). Together with large-scale circulation, these AGWs/TADs transport energy and momentum away from their sources. In this paper, we investigate possible involvement of AGWs/TADs during solar flares. Model simulations of an X17 flare that occurred on October 28, 2003 shows that AGWs/TADS contributed to flare energy transport from the sunlit South-Pole region to the nightside equatorial region in 3–4 h, resulting in ~10% nightside equatorial neutral density enhancement in the upper thermosphere. These nightside AGWs/TADs have a phase speed on the order of ~750 m/s and a horizontal wavelength on the order of 4000 km. Enhanced solar heating to the thermosphere through enhanced ionization during flares occurs on the entire dayside, with the spatial scale of the increased solar heating being too large to excite AGWs/TADs. Further analysis revealed that strong localized enhancement of Joule heating was produced during the October 28, 2003 flare. This sudden injection of the localized heating, together with preexisting AGWs/TADs excited by moderate geomagnetic activity prior to the flare, produced intensified AGWs/TADs, which propagated energy and momentum to the equatorial region. On the other hand, model simulations showed that, under assumed geomagnetically quiet conditions, strong localized enhancement of Joule heating and AGWs/TADs were not produced during the flare. This interplay between geomagnetic activity and solar flares can be a challenge to space weather monitoring, specification, and forecasting.

Figure 1 caption: Night-side traveling atmospheric disturbance during and after the X17 flare occurred on October 28, 2003. The sudden increase of the GOES X-ray started at 11:00 UT, peaked at 11:10 UT, and recovered at ~12:00 UT. (a) CHAMP night-side neutral density (01:05 LT); (b) TIE-GCM simulated neutral density. The TIE-GCM neutral density was sampled along the CHAMP ascending orbits (night-side part of the orbits).

Figure 2: High resolution

(2) Qian, L., A. G. Burns, S. C. Solomon, and P. C. Chamberlin . 2012: Solar flare impacts on ionospheric electrodyamics, Geophys. Res.Lett., 39, L06101, doi:10.1029/2012GL051102.

Abstract: The sudden increase of X-ray and extreme ultra-violet irradiance during flares increases the density of the ionosphere through enhanced photoionization. In this paper, we use model simulations to investigate possible additional contributions from electrodynamics, finding that the vertical E×B drift in the magnetic equatorial region plays a significant role in the ionosphere response to solar flares. During the initial stage of flares, upward E×B drifts weaken in the magnetic equatorial region, causing a weakened equatorial fountain effect, which in turn causes lowering of the peak height of the F2 region and depletion of the peak electron density of the F2 region. In this initial stage, total electron content (TEC) enhancement is predominantly determined by solar zenith angle control of photoionization. As flares decay, upward E×B drifts are enhanced in the magnetic equatorial region, causing increases of the peak height and density of the F2 region. This process lasts for several hours, causing a prolonged F2-region disturbance and TEC enhancement in the magnetic equator region in the aftermath of flares. During this stage, the global morphology of the TEC enhancement becomes predominantly determined by these perturbations to the electrodynamics of the ionosphere.

Figure 2 caption: TIE-GCM simulated ime series of ionosphere responses to the X17 flare that occurred on October 28, 2003. (a): change of vertical plasma velocity (vertical E×B drifts) at lev=2 (P_0/P, P_0= 5×10_−4µb), at 12:00LT at the magnetic equator; (b) rate of change of electron density due to the vertical E×B drifts at 12:00LT at the magnetic equator; (c) change of electron density at 12:00LT at the magnetic equator; (d) Integrated EUV from 5–105nm calculated by FISM (black line) and observed by TIMED SEE (red star).