TY - JOUR
T1 - Modeling the ionospheric prereversal enhancement by using coupled thermosphere-ionosphere data assimilation
AU - Chen, Chia Hung
AU - Lin, Charles
AU - Chen, Wei Han
AU - Matsuo, Tomoko
N1 - Funding Information:
This paper is supported by the Ministry of Science and Technology (MOST) and the National Space Organization (NSPO) of Taiwan to National Cheng Kung University under MOST-103-2111-M-006-003-MY3, 105-2111-M-006-003, 105-2111-M-006-008, 105-2119-M-006-025, and NSPO-S-105120. T.M. is supported by NASA award NNX14AI17G and AFOSR award FA9550-13-1-0058. The source code for the assimilation system and the simulation model used in this study, the DART and TIEGCM, are available at http://www.image.ucar.edu/DAReS/DART/ and http://www.hao.ucar.edu/modeling/tgcm/, respectively. The observation data from ground-based GPS receivers are available at IGS (https://igscb.jpl.nasa.gov/components/data.html). The authors are grateful for the NCAR High Altitude Observatory and Data Assimilation Research Section for their support of TIEGCM and DART software. The authors gratefully acknowledge the constructive comments given by the two anonymous reviewers. Charles Lin thanks Arthur D. Richmond for the useful discussion on the updated mechanisms of prereversal enhancement during the manuscript preparations.
PY - 2017/2/28
Y1 - 2017/2/28
N2 - We report that assimilating total electron content (TEC) into a coupled thermosphere-ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward prereversal enhancement (PRE) electric field (E field). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature, and compositions are adjusted simultaneously. The improvement of duskside PRE E field calculation over the prior state is achieved primarily by intensification of eastward neutral wind. The improved E field calculation promotes a stronger plasma fountain and deepens the equatorial trough. As a result, the horizontal gradients of Pedersen conductivity and eastward wind are increased due to greater zonal electron density gradient and smaller ion drag at dusk, respectively. Such modifications provide preferable conditions and obtain a strengthened PRE magnitude closer to the observation. The adjustment of PRE E field is enabled through self-consistent thermosphere and ionosphere coupling processes captured in the model. This study suggests that the PRE E field that is critical in driving the evening equatorial plasma instability could be better forecasted by assimilation of TECs in the 10 min cycling.
AB - We report that assimilating total electron content (TEC) into a coupled thermosphere-ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward prereversal enhancement (PRE) electric field (E field). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature, and compositions are adjusted simultaneously. The improvement of duskside PRE E field calculation over the prior state is achieved primarily by intensification of eastward neutral wind. The improved E field calculation promotes a stronger plasma fountain and deepens the equatorial trough. As a result, the horizontal gradients of Pedersen conductivity and eastward wind are increased due to greater zonal electron density gradient and smaller ion drag at dusk, respectively. Such modifications provide preferable conditions and obtain a strengthened PRE magnitude closer to the observation. The adjustment of PRE E field is enabled through self-consistent thermosphere and ionosphere coupling processes captured in the model. This study suggests that the PRE E field that is critical in driving the evening equatorial plasma instability could be better forecasted by assimilation of TECs in the 10 min cycling.
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U2 - 10.1002/2016GL071812
DO - 10.1002/2016GL071812
M3 - Article
AN - SCOPUS:85014098425
VL - 44
SP - 1652
EP - 1659
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 4
ER -