Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars

Janches, Diego; Heinselman, C. J.; Chau, Jorge L.; Chandran, Amal; Woodman, R. F.

doi:10.1029/2006ja011628

Cited by 101 publications

(135 citation statements)

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“…Furthermore, most of the daily mass input originates from the sporadic meteor background, which is the interplanetary dust forming the Zodiacal dust cloud. The orbits of the meteoroids from that source are so evolved that they cannot be traced back to their original parent body (Brown and Jones, 1995;Janches et al, 2006;Fentzke and Janches, 2008). The constant bombardment of particles from the sporadic background contributes far more input than meteor showers (e.g.…”

Section: Introductionmentioning

confidence: 99%

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

et al. 2015

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Abstract. Mg and Mg + concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg + dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly mean Mg and Mg + number density and vertical column density in different latitudinal regions are presented. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which cover the 50 to 150 km altitude region with a vertical sampling of ≈ 3.3 km and latitudes up to 82• . The high latitudes are not observed in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm −3 and 1500 cm −3 . Mg does not show strong seasonal variation at latitudes below 40 • . For higher latitudes the density is lower and only in the Northern Hemisphere a seasonal cycle with a summer minimum is observed. The Mg + peak occurs 5-15 km above the neutral Mg peak altitude. These ions have a significant seasonal cycle with a summer maximum in both hemispheres at mid and high latitudes. The strongest seasonal variations of Mg + are observed at latitudes between 20 and 40• and the density at the peak altitude ranges from 500 cm −3 to 4000 cm −3 . The peak altitude of the ions shows a latitudinal dependence with a maximum at mid latitudes that is up to 10 km higher than the peak altitude at the equator.The SCIAMACHY measurements are compared to other measurements and WACCM model results. The WACCM results show a significant seasonal variability for Mg with a summer minimum, which is more clearly pronounced than for SCIAMACHY, and globally a higher peak density than the SCIAMACHY results. Although the peak density of both is not in agreement, the vertical column density agrees well, because SCIAMACHY and WACCM profiles have different widths. The agreement between SCIAMACHY and WACCM results is much better for Mg + with both showing the same seasonality and similar peak density. However, there are also minor differences, e.g. WACCM showing a nearly constant altitude of the Mg + layer's peak density for all latitudes and seasons.

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Section: Introductionmentioning

confidence: 99%

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

et al. 2015

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“…However, while the data show a difference between September (highest detection rate) and March (lowest detection rate) by a factor of 5, the model varies by a significantly smaller factor. For the case of the radial velocity distributions displayed in Figure 10, however, the disagreement is even greater than for the case of AO where ZoDy predicts 400 to 500 times more particles at the peak of the distribution than those detected by the radar if J this is partly due to the fact that PFISR will observe the incoming flux, on average, at a shallower entry angle than AO due to its higher latitude location (Janches et al 2006;Fentzke et al 2009;Sparks et al 2009), which results in an increase of lower radial velocities, specially by the faster and larger particles that PFISR is able to detect. This once again shows that the hypothesis that the small and slow flux is undetected is supported by this work, and that the large disagreement reported by Jones (1997), while the dotted lines use the revised value R ip 2 b reported in Paper I.…”

Section: Implementation To the Zodiacal Dust Modelmentioning

confidence: 65%

“…Both quantities are strongly dependent on the time-of-day, day-of-year and location of the observations (Janches et al 2006;. We note that for the case of AO and PFISR, the observations utilized in this work were obtained without the use of interferometry, and thus the results do not have information regarding direction.…”

Section: Implementation To the Zodiacal Dust Modelmentioning

confidence: 99%

“…1N for PFISR). These differences have been demonstrated to be caused, at least in part, by the visibility of the different apparent sporadic meteor sources at each location and season (Janches et al 2006;Fentzke et al 2009;Pifko et al 2013). Second, each system has significant differences in detection sensitivity, and thus they enable the detection of somewhat different portions of the incoming flux (Janches et al , 2014aFentzke et al 2009;Pifko et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

Janches

Swarnalingam

Plane

et al. 2015

ApJ

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The sensitivity of radar systems to detect different velocity populations of the incoming micrometeoroid flux is often the first argument considered to explain disagreements between models of the Near-Earth dust environment and observations. Recently, this was argued by Nesvorný et al. to support the main conclusions of a Zodiacal Dust Cloud (ZDC) model which predicts a flux of meteoric material into the Earth's upper atmosphere mostly composed of small and very slow particles. In this paper, we expand on a new methodology developed by Janches et al. to test the ability of powerful radars to detect the meteoroid populations in question. In our previous work, we focused on Arecibo 430 MHz observations since it is the most sensitive radar that has been used for this type of observation to date. In this paper, we apply our methodology to two other systems, the 440 MHz Poker Flat Incoherent Scatter Radar and the 46.5 Middle and Upper Atmosphere radar. We show that even with the less sensitive radars, the current ZDC model over-predicts radar observations. We discuss our results in light of new measurements by the Planck satellite which suggest that the ZDC particle population may be characterized by smaller sizes than previously believed. We conclude that the solution to finding agreement between the ZDC model and sensitive high power and large aperture meteor observations must be a combination of a re-examination not only of our knowledge of radar detection biases, but also the physical assumptions of the ZDC model itself.

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“…[5] The radar observations used for this work were designed to study the spring variability of the diurnal micrometeor flux detected at Arecibo [Janches et al, 2006]. They cover mostly 24 hour periods prior to, near, and after the northern hemisphere spring equinox.…”

Section: Experiments Description and Observationsmentioning

confidence: 99%

Diurnal variability of the gyro resonance line observed with the Arecibo incoherent scatter radar at E‐ and F1‐region altitudes

Janches

Nicolls

2007

Geophysical Research Letters

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[1] In this paper, we report on observations of the diurnal variation of a resonance line that occurs near the gyro frequency as seen with the incoherent scatter radar (ISR) at the Arecibo Observatory. This gyro resonance line has rarely been observed in ISR data, but recent results, exemplified by the observations of Bhatt et al. (2006), have implied that the gyro line is a common ionospheric feature. The observations presented here were made with much better altitude resolution in comparison with previous results and represent full 24 hour coverage for several days. The data indicate that an increase in the gyro line intensity near sunrise and sunset is an everyday occurrence. As the increase in intensity is occurring at sunset, the gyro line frequency drops from the expected frequency to one near zero frequency. As the increase in intensity is occurring at sunrise, the gyro line frequency increases from near zero frequency to one near the expected gyro line frequency. This behavior of the gyro line frequency and intensity has not been observed before. We explain these results using normal Maxwellian incoherent scatter theory together with the diurnal variation of the density in the E and F1 regions. These results may explain previous observations of the gyro line made at Arecibo and suggest avenues of future research for studying this exciting feature of the incoherent scatter spectrum. Citation: Janches, D., and M. J. Nicolls (2007), Diurnal variability of the gyro resonance line observed with the Arecibo incoherent scatter radar at E-and F1-region altitudes,

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Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars

Cited by 101 publications

References 37 publications

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

Global investigation of the Mg atom and ion layers using SCIAMACHY/Envisat observations between 70 and 150 km altitude and WACCM-Mg model results

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

Diurnal variability of the gyro resonance line observed with the Arecibo incoherent scatter radar at E‐ and F1‐region altitudes

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