Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector
Abstract
:1. Introduction
2. Data and Methodology
Keograms
3. Results
4. Discussion
5. Summary and Conclusions
- In general, mean zonal drift velocities of EPBs decrease throughout the night. Larger velocity events travel at ≈150 ms−1 (usually occurring during earlier hours of an observation period), while slower events move at ≈60 ms−1 (occurring late in an observation period). The decreasing rate is ≈10 ms−1/h.
- Typically, faster EPBs occur from 20 LT to 23 LT in the west-most region of the zonal keograms in a longitude range of −37° to −33°. The longitudinal gradient in the bubble drift velocity indicates a vertical gradient in the thermospheric wind that controls plasma drifts in the nighttime F region ionosphere. The keogram method can be used to describe these vertical gradients in the thermospheric wind, assuming that the EPBs drift eastward with the zonal wind.
- Our keogram technique compares favorably with the mosaic method [9]. A Gaussian curve fits the velocity differences distribution of well. The standard deviation of the residuals distribution is large (≈15 ms−1). Moreover, >30% of the residuals of have values larger than 15 ms−1, which points out to possible refining of the methods.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Vargas, F.; Brum, C.; Terra, P.; Gobbi, D. Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector. Atmosphere 2020, 11, 69. https://doi.org/10.3390/atmos11010069
Vargas F, Brum C, Terra P, Gobbi D. Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector. Atmosphere. 2020; 11(1):69. https://doi.org/10.3390/atmos11010069
Chicago/Turabian StyleVargas, Fabio, Christiano Brum, Pedrina Terra, and Delano Gobbi. 2020. "Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector" Atmosphere 11, no. 1: 69. https://doi.org/10.3390/atmos11010069
APA StyleVargas, F., Brum, C., Terra, P., & Gobbi, D. (2020). Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector. Atmosphere, 11(1), 69. https://doi.org/10.3390/atmos11010069