Mesospheric doppler wind measurements from Aura Microwave Limb Sounder (MLS)

This paper describes a microwave limb technique for measuring Doppler wind in the Earth’s mesosphere. The research algorithm has been applied to Aura Microwave Limb Sounder (MLS) 118.75 GHz measurements where the O₂ Zeeman lines are resolved by a digital autocorrelation spectrometer. A precision of ∼17 m/s for the line-of-sight (LOS) wind is achieved at 80–92 km, which corresponds to radiometric noise during 1/6 s integration time. The LOS winds from Aura MLS are mostly in the meridional direction at low- and mid-latitudes with vertical resolution of ∼8 km. This microwave Doppler technique has potential to obtain useful winds down to ∼40 km of the Earth’s atmosphere if measurements from other MLS frequencies (near H₂O, O₃, and CO lines) are used. Initial analyses show that the MLS winds from the 118.75 GHz measurements agree well with the TIDI (Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer) winds for the perturbations induced by a strong quasi 2-day wave (QTDW) in January 2005. Time series of MLS winds reveal many interesting climatological and planetary wave features, including the diurnal, semidiurnal tides, and the QTDW. Interactions between the tides and the QTDW are clearly evident, indicating possible large tidal structural changes after the QTDW events dissipate.     

Mean energy of response to galactic cosmic ray spectrum: IMP 8 and Climax neutron monitor

Solar modulations of galactic cosmic ray (GCR) intensity contain a wealth of information about their transport in the heliosphere. To extract this information from the data one studies the dependence of the observed modulations on the mean energy of response of detectors providing data for the analyses. There is a great deal of confusion about the detector energy response to GCR spectrum in the literature. We present a preliminary report on the computations of the mean energy of response for the Climax neutron monitor (CL/NM) and IMP 8 cosmic ray nuclear composition instrument to GCR protons for 1973–1998, covering the solar cycles 21 and 22. We find that for penetrating proton channel on IMP 8 the mean energy changes by a factor of over two whereas for the neutron monitor the change is only 21%. However, the corresponding change for the computed modulation function is a factor of about 3.5.     

Aerosols and clouds in the upper troposphere–lower stratosphere region detected by GOMOS and ACE: Intercomparison and analysis of the years 2004 and 2005

Satellite-based limb occultation measurements are well suited for the detection and mapping of polar stratospheric clouds (PSCs) and cirrus clouds. PSCs are of fundamental importance for the formation of the Antarctic ozone hole that occurs every year since the early 1980s in Southern Hemisphere spring. Despite progress in the observation, modeling and understanding of PSCs in recent years, there are still important questions which remain to be resolved, e.g. PSC microphysics, composition, formation mechanisms and long-term changes in occurrence. In addition, it has recently become clear that cirrus clouds significantly affect the global energy balance and climate, due to their influence on atmospheric thermal structure.     

Remote upgrading of a space-borne instrument

The main purposes of experiment “Obstanovka” (“Environment” in Russian) consisting of several instruments are to measure a set of electromagnetic and plasma phenomena characterizing the space weather conditions, and to evaluate how such a big and highly energy consuming body as the International Space Station disturbs the surrounding plasma, and how the station itself is charged due to the operation of so many instruments, solar batteries, life supporting devices, etc. Two identical Langmuir electrostatic probes are included in the experiment “Obstanovka”. In this paper the Langmuir probes for “Obstanovka” experiment are described, including the choice of geometry (spherical or cylindrical), a more reliable method for the sweep voltage generation, an adaptive algorithm for the probe’s operation. Special attention is paid to the possibility for remote upgrading of the instrument from the ground using the standard communication channels.     

The relation between the Black hole mass and the Bulge mass for low redshift AGNs. Part I: Ground-based observations

Using the bulge data from AGN image decomposition with ground-based observations, we calculate the ratios of the central supermassive black hole mass(SMBH) to the Bulge mass (_Mbh/_Mbulge$M_{\text{bh}}/M_{\text{bulge}}$) in a sample of X-ray selected AGNs, including 15 Narrow-line Seyfert 1 galaxies (NLS1s) and 18 broad-line Seyfert 1 galaxies (BLS1s). We found that the mean value of log(_Mbh/_Mbulge)$\log (M_{\text{bh}}/M_{\text{bulge}})$ is -3.81±0.11$-3.81\pm 0.11$ for 15 NLS1s, and -2.91±0.13$-2.91\pm 0.13$ for 18 BLS1s, showing the lower _Mbh/_Mbulge$M_{\text{bh}}/M_{\text{bulge}}$ in NLS1s relative to BLS1s. The calculation shows that the Bulge mass from the host image decomposition in NLS1s is statistically smaller than that from Hubble-type correction method, and a linear mass relation is suggested for NLS1s and a nonlinear mass relation for BLS1s. The studying of host galaxies with ground-based observations strongly limited by the atmospheric seeing. We need to do the decomposition of host images for NLS1s with Hubble Space Telescope observation in the future.     

Interstellar planetary protection

In the coming decades the detection of Earth-like extrasolar planets, either apparently lifeless or exhibiting spectral signatures of life, will encourage design studies for craft to visit them. These missions will require the elaboration of an interstellar planetary protection protocol. Given a specific dose required to sterilize microorganisms on a spacecraft, a critical mean velocity can be determined below which a craft becomes self-sterilizing. This velocity is calculated to be below velocities previously projected for interstellar missions, suggesting that an active sterilization protocol prior to launch might be required. Given uncertainties in the surface conditions of a destination extrasolar planet, particularly at microscopic scales, the potential for unknown biochemistries and biologies elsewhere, or the possible inoculation of a lifeless planet that is habitable, then both lander and orbiter interstellar missions should be completely free of all viable organisms, necessitating a planetary protection approach applied to orbiters and landers bound for star systems with unknown local conditions for habitability. I discuss the case of existing craft on interstellar trajectories – Pioneer 10, 11 and Voyager 1 and 2.     

Influence of the 27-day solar flux variations on the ionosphere parameters measured at Irkutsk in 2003–2005

We present an investigation of the influence of the 27-day solar flux variations, caused by solar rotation, on the ionosphere parameters such as the F2 layer critical frequency (foF2) and the total electron content (TEC). Our observational data were obtained with the Irkutsk Digisonde (DPS-4) located at 52.3 North and 104.3 East during the period from 2003 to 2005. In addition, we use TEC data from the Global Ionosphere Maps (GIM) based on Global Positioning System (GPS) satellites. The solar radiation flux at a wavelength of 10.7 cm (F10.7 index) is used as an index characterizing the solar activity level. A good correlation between observed ionosphere parameters and solar activity variations is found especially in autumn-to-winter season. We estimate the impact of the 27-day solar flux variations on the day-to-day variability and determine the time delay of the ionosphere response.     

A steady-state model for the D- to F-region of the polar cap

For obvious reasons the ionosphere of the polar cap, surrounded by the auroral zone, is only poorly investigated. Even ionosonde data are very scant from geomagnetic latitudes beyond 70°. Since 1997 the European incoherent scatter radar facility EISCAT has an additional installation on Svalbard and has been providing electron density data nearly continuously ever since. These measurements which mainly cover the E- and F-regions are supplemented by rocket data from Heiss Island at a comparable magnetic latitude; these data are more sporadic, but cover lower altitudes and densities. A provisional, steady-state, neural network-based model is presented which uses the data of both sites.