Browsing by Author "Chen, C. Y."
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Item Restricted Electron density profiles in the equatorial ionosphere observed by the FORMOSAT-3/COSMIC and a digisonde at Jicamarca(Springer, 2009-11-26) Liu, J. Y.; Lee, C. C.; Yang, J. Y.; Chen, C. Y.; Reinisch, B. W.We examine for the first time the ionospheric electron density profiles concurrently observed by the GPS occultation experiment (GOX) onboard the FORMOSAT-3/COSMIC (F3/C) and the ground-based digisonde portable sounder DPS-4 at Jicamarca (12°S, 283°W, 1°N geomagnetic) in 2007. Our results show that the F3/C generally underestimates the F2-peak electron density NmF2 and the F2-peak height hmF2. On the other hand, when the equatorial ionization anomaly (EIA) pronouncedly appears during daytime, the total electron content (TEC) derived from the radio occultation of the GPS signal recorded by the F3/C GOX is significantly enhanced. This results in the NmF2 at Jicamarca being overestimated by the Abel inversion on the enhanced TEC during the afternoon period.Item Open Access Persistence of a Kelvin-Helmholtz instability complex in the upper troposphere(American Geophysical Union, 2005-07-27) Kelley, M. C.; Chen, C. Y.; Beland, R. R.; Woodman Pollitt, Ronald Francisco; Chau Chong Shing, Jorge Luis; Werne, J.During the period of 7–14 September 1998 a multiple instrument campaign was conducted at the Jicamarca Radio Observatory (JRO) near Lima, Peru, using a 50-MHz VHF radar and radiosondes. In this paper we discuss the radar and in situ observations and interpret them with insight gained from high-resolution numerical simulations of the Kelvin-Helmholtz instability (KHI). Evidence is presented that a large-scale shear in the upper troposphere on 8 September 1998 becomes locally unstable due to ambient gravity wave activity. Isolated KHI events result and subsequently grow and merge to form a large 3-km mixing layer. A 3-km-deep potential-temperature step is observed at the same altitude at least a full day after the initial observations. Analysis indicates that neither turbulent mixing nor radiative cooling is capable of destroying the fully developed temperature step in the 21 hours available, which lends credence to the hypothesis that the structure persisted for this period of time. Alternately, the structure could be continuously generated by a standing wave associated with mountain wave forcing.