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Large‐scale periodic plasma bubbles are often observed by ionospheric radars and satellites. The seeding effect of atmospheric gravity waves has been widely used to explain the generation of periodic plasma bubbles. However, it has not been well understood where the seeding process occurs and how a series of plasma bubbles is triggered. In this study, we present the observations of equatorial plasma bubbles by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. We show examples of quasiperiodic plasma bubbles in the post‐midnight sector, with nearly equal distance of 800–1000 km between adjacent bubbles, in 2008 under deep solar minimum conditions. The bubble chain covered a longitudinal range of ~7000 km between 00:00 and 04:00 LT. Quasiperiodic plasma bubbles were also measured by C/NOFS in the evening sector in 2011 during the ascending phase of the solar activity, and the longitudinal distance between adjacent bubbles was ~500 km. We propose a causal mechanism to explain the generation of quasiperiodic plasma bubbles. In this scenario, atmospheric gravity waves are generated near the sunset terminator and initiate the Rayleigh‐Taylor instability there. The spatial (longitudinal) periodicity of plasma bubbles is determined by the temporal periodicity of the seeding gravity waves. A period of 15–30 min of the seeding gravity waves corresponds to a longitudinal separation of 500–1000 km between adjacent bubbles. This mechanism provides a reasonable explanation of the observed quasiperiodic plasma bubbles. New C/NOFS observations of periodic plasma bubbles are presented.The periodic bubbles have 7‐14 cycles with wavelengths of 500‐1000 km.New causal mechanism for the periodic plasma bubbles is proposed.

Mass spectrometry is a versatile research tool that has proved to be extremely useful for exploring the fundamental nature of the earth's atmosphere and ionosphere and in helping to solve operational problems facing the Air Force and the Department of Defense. In the past 40 years, our research group at the Air Force Research Laboratory has flown quadrupole mass spectrometers of many designs on nearly 100 sounding rockets, nine satellites, three Space Shuttles and many missions of high-altitude research aircraft and balloons. We have also used our instruments in ground-based investigations of rocket and jet engine exhaust, combustion chemistry and microwave breakdown chemistry. This paper is a review of the instrumentation and techniques needed for space research, a summary of the results from many of the experiments, and an introduction to the broad field of atmospheric and space mass spectrometry in general. Copyright © 1999 John Wiley & Sons, Ltd.

It has been observed that the zonal drift velocity of equatorial plasma bubbles is generally eastward. However, it has not been well understood whether the zonal drift of plasma bubbles is the same as the ambient plasma drift and what process causes differences in the drift velocities of the ambient plasma and bubbles. In this study we analyze the ion drift velocities measured by the Defense Meteorological Satellites Program and ROCSAT‐1 satellites and the electric fields measured by the Communications/Navigation Outage Forecasting System (C/NOFS) satellite in the presence of equatorial spread F. We find that the zonal drift velocity of the plasma particles inside plasma bubbles is significantly different from the ambient plasma drift. The relative zonal velocity of the ions inside the depletion region with respect to the ambient plasma is generally westward. In most cases it can be as high as several hundreds of meters per second. The plasma bubbles detected by the C/NOFS satellite in the midnight‐dawn sector are still growing, and the polarization electric field inside the postmidnight bubbles is much stronger than the electric field in the ambient plasma. We suggest that the zonal drift velocity of the plasma particles inside the depletion region is driven by polarization electric field. When a plasma bubble is tilted, the E× Bdrift velocity caused by the polarization electric field has an upward component and a zonal component. Because of the zonal motion of the plasma particles inside the bubble, the eastward drift velocity of the bubble structure is faster than the ambient plasma drift for a west‐tilted bubble and slower than the ambient plasma drift for an east‐tilted bubble.

Measurements of HNO3mixing ratios from the chemical ionization mass spectrometer have been critically compared with simultaneous measurements of total gas phase NOyfrom the NO chemiluminescence detector aboard the NASA DC‐8 aircraft during the SAGE 3 Ozone Loss and Validation Experiment (SOLVE). The data were obtained in the arctic upper troposphere and lower stratosphere in the winter of 1999–2000. A brief comparison to the NOyinstrument aboard the NASA ER‐2 is also presented. The time responses, detection limits, relative precision, and stability of relative calibrations for the instruments were in excellent agreement throughout the mission. However, the average slope of the HNO3to NOycorrelation was 1.13 ± 0.03 overall and 1.06 ± 0.03 in stratospheric air, indicating that the two measurements had a systematic calibration offset. Possible sources for the offset error are presented, and methods to reduce the calibration error in future flights are suggested.

NOy(total reactive nitrogen) contained in ice particles was measured on board the NASA DC‐8 aircraft in the Arctic in January and March 2000. During some of the flights, the DC‐8 encountered widespread cirrus clouds. Large quantities of ice particles were observed at 8–12 km and particulate NOyshowed large increases. The data indicate that the amount of NOycovering the cirrus ice particles strongly depended on temperature. Similar measurements were made in the upper troposphere over the tropical Pacific Ocean in August–September 1998 and 1999. The data obtained in the Arctic and tropics show very limited uptake of NOyon ice at temperatures above 215 K.