Initial Results of Meteor Wind with Langfang Medium Frequency Radar

We conducted meteor observations during the Leonid meteor shower on 16 November 2017 and 17 November 2018 with Langfang medium frequency (MF) radar (116° E, 40° N). This was the first nighttime meteor observation by MF radar in mid-latitude China. The observation period was 12:00–22:00 (UT) and the observation range was 78–150 km. By using broad vertical beams, totally 94 and 92 meteor echoes were obtained, along with their spatial, time and height distribution. Quite a few meteor echoes are within 30° zenith angles, from the southwest direction, and with a mean height of 107 km which is almost 10 km higher than traditional VHF (Very High Frequency) meteor radar observations. Initial bi-hourly and nightly averaged wind profiles were calculated, and well fitted the wind estimations by co-located VHF meteor radar at the altitude of 100–110 km. On the other side, echoes around 140 km are successfully detected in our observation, which may suggest that for most running MF radars, meteor echoes around 140 km altitude could be detected with a sampling pulse frequency less than 100 Hz.

Design of Multifunctional Mesosphere-Ionosphere Sounding System and Preliminary Results

This paper describes a novel sounding system for which the functions of the medium frequency (MF) radar and the ionosonde are integrated on the same hardware platform and antenna structure, namely the middle atmosphere-ionosphere (MAI) system. Unlike the common MF radar, MAI system adopts the pseudo-random (PRN) phase-coded modulation technology, which breaks the limitation of the traditional monopulse mode. Through the pulse compression, only a small peak power is needed to achieve the signal-to-noise ratio (SNR) requirement. The excellent anti-jamming performance is also very suitable for the ionospheric sounding. One transmitting and six receiving modes are adopted for the MF sounding. While neglecting the structure of the T/R switches, the coupling interference between the transmitter and the receiver may also be avoided. Moreover, by employing a miniaturized antenna array composed of progressive-wave antennas for the MF receiving and ionospheric sounding, the MAI system takes account of the requirements of the inversion algorithms of MF radar and the large bandwidth need for the ionospheric sounding concurrently. Such an antenna structure can also greatly simplify the system structure and minimize the difficulty of deployment. The experiments verified the availability of the system scheme and its engineering application significance. Through further analysis of the sounding data, the wind field of the mesosphere, the electron density of D layer and electron density profile from layers E to F were obtained at the identical location. The capability of MAI system can play an important role in studying the interaction and coupling mechanism between the mesosphere and ionosphere.

D region observations by VHF and HF radars during a rocket campaign at Andøya dedicated to investigations of PMWE

In April 2018 the PMWE1 sounding rocket campaign was conducted at the Andøya Space Center involving coordinated measurements with rockets and ground instruments to measure parameters relevant for testing of the existing theories of polar mesospheric winter echo (PMWE) formation. The Middle Atmosphere Alomar Radar System (MAARSY) was operated to detect PMWE with multiple beam directions to detect favorable launch conditions. A dedicated experiment configuration with five different beam positions was used to point the radar beam along the planned trajectory of the payload. This special radar experiment allowed to obtain basic information about the spatial structure of the PMWE and its dynamical behavior around the flight of the two rockets. PMWE with signal strengths between 10−17 and 10−15 m−1 have been observed by MAARSY during the whole campaign period, starting with a moderate occurrence at the beginning which decreased towards the end of the campaign. Furthermore real common-volume observations by rocket instruments and radar soundings have been carried out at PMWE altitudes on up-leg and down-leg of the rocket flights. The Saura MF radar was operated during both flights probing the mesosphere with a multiple beam scan experiment to derive horizontal winds and electron density profiles. The obtained PMWE characteristics as signal strength and spectral width of the received radar signals as well as estimated horizontal winds and electron densities are presented with particular emphasis to the launch times of the sounding rockets.

Struktur Vertikal Gelombang Planeter Di Mesosfer Ekuator Dari Pengamatan MF Radar Pontianak (0.03LU -109.3BT)

Gelombang atmosfer memainkan peranan yang penting dalam dinamika atmosfer. Mekanisme pembentukan, penjalaran dan pecahnya gelombang atmosfer sangat menarik untuk dipelajari terutama di wilayah ekuator karena penelitian di lintang tengah mengindikasikan bahwa ekuator adalah dinamo atmosfer global. Data angin dari pengamatan Medium Frequency Radar (MF Radar) di Pontianak pada ketinggian tertentu dari 78 km sampai dengan 98 km, tahun 1996 digunakan untuk mendapatkan struktur vertikal variasi gelombang planeter angin zonal dan meridional di daerah mesosfer. Intensitas variasi angin zonal umumnya lebih tinggi dari pada angin meridional. Variasi gelombang planeter menurut posisi matahari juga akan didiskusikan. Berbeda dengan hasil penelitian di daerah lintang tinggi dan lintang tengah yang memiliki pola tertentu1), di Pontianak variasi gelombang planeter menurut posisi matahari tidak menunjukkan pola tertentu

ANALISIS KECEPATAN ANGIN MESOSFER DAN TERMOSFER BAWAH DAERAH EKUATOR INDONESIA DARI PENGAMATAN MF RADAR

Variasi komponen pasut diurnal dan semidiurnal dari data angin zonal dan meridional untuk stasiun Pameungpeuk dan Pontianak akan dianalisis untuk mengetahui bagaimana pola musiman pasut diurnal dan semidiurnalnya. Data yang digunakan adalah data jam-an kecepatan angin zonal dan meridional keluaran MF Radar Pontianak dan Pameungpeuk. Data stasiun Pontianak tahun 2004 dan data stasiun Pameungpeuk dari tahun 2005 sampai dengan tahun 2006. Dengan memanfaatkan persamaan harmonik untuk gelombang pasut dan mencari solusinya, maka akan diperoleh amplitudo komponen-komponen pasut baik diurnal maupun semidiurnal angin zonal dan meridional. Data amplitudo pasut bulanan akan memberikan informasi bagaimana variasi kecepatan angin pada ketinggian 90 km (Mesosfer-Lower Termosfer) di atas Pameungpeuk dan Pontianak. Hasilnya menunjukkan bahwa variasi musiman terlihat jelas pada angin rata-rata baik di atas Pameungpeuk dan Pontianak. Komponen-komponen pasut diurnal dan semidiurnal untuk stasiun Pontianak mencapai maksimum saat matahari berada dekat ekuator dan sebaliknya mencapai minimum pada saat bulan-bulan matahari jauh dari ekuator. Sementara untuk stasiun Pameungpeuk nilai maksimum dan minimumnya lebih bervariasi. Hasil-hasil analisis kecepatan angin di atas dibandingkan juga dengan hasil-hasil analisis serupa untuk daerah ekuator lainnya, dalam hal ini dibandingkan dengan Brazil. Pola angin mesosfer di atas Pontianak memiliki kesamaan dan perbedaan dengan pola angin mesosfer di atas Cariri, Brazil. Kesamaannya ada pada pola angin rata-rata baik zonal maupun meridional. Sedangkan perbedaannya ada pada pasut diurnal dan semidiurnal dan perbandingan besar gelombang pasut zonal dan meridional

A comparison of 11-year mesospheric and lower thermospheric winds determined by meteor and MF radar at 69 ° N

The Andenes Meteor Radar (MR) and the Saura Medium Frequency (MF) Radar are located in northern Norway (69° N, 16° E) and operate continuously to provide wind measurements of the mesosphere and lower thermosphere (MLT) region. We compare the two systems to find potential biases between the radars and combine the data from both systems to enhance altitudinal coverage between 60 and 110 km. The systems have altitudinal overlap between 78 and 100 km at which we compare winds and tides on the basis of hourly winds with 2 km altitude bins. Our results indicate reasonable agreement for the zonal and meridional wind components between 78 and 92 km. An exception to this is the altitude range below 84 km during the summer, at which the correlation decreases. We also compare semidiurnal and diurnal tides according to their amplitudes and phases with good agreement below 90 km for the diurnal and below 96 km for the semidiurnal tides. Based on these findings we have taken the MR data as a reference. By comparing the MF and MR winds within the overlapping region, we have empirically estimated correction factors to be applied to the MF winds. Existing gaps in that data set will be filled with weighted MF data. This weighting is done due to underestimated wind values of the MF compared to the MR, and the resulting correction factors fit to a polynomial function of second degree within the overlapping area. We are therefore able to construct a consistent and homogenous wind from approximately 60 to 110 km.

Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

Mesospheric gravity wave (GW) momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E) experiments (conducted from July 1997 to June 1998) are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions). The received beams were analysed with hybrid Doppler interferometry (HDI) (Holdsworth and Reid, 1998), principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997), later re-introduced by Hocking (2005) and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010) of the accuracy of the meteor radar technique.