The global distribution and variability of stratospheric constituents measured by LIMS

The purpose of the Nimbus 7 LIMS experiment was to sound the composition and structure of the upper atmosphere and provide data for study of photochemistry, radiation, and dynamics processes. Vertical profiles were measured of temperature and ozone (O₃) over the 10-km to 65-km range and water vapor (H₂O), nitrogen dioxide (NO₂), and nitric acid (HNO₃) over the 10-km to ～50-km range. Latitude coverage extended from 64°S to 84°N. Several general features of the atmosphere have emerged from data analyses thus far. Nitrogen dioxide exhibits rapid latitudinal variations in winter and shows hemispheric asymmetry with generally higher vertical column amount in the summer hemisphere. HNO₃ data show that this gas is highly variable with altitude, latitude, and season. Smallest mixing ratios occur in the tropics, and the largest values occur in the high latitude winter hemisphere. The results show that O₃, NO₂, and HNO₃ are strongly affected during a stratospheric warming. There is a persistently low water vapor mixing ratio in the tropical lower stratosphere (～2–3 ppmv), a poleward gradient at all times in the mission, and evidence of increasing mixing ratio with altitude at tropical and middle latitudes.     

Balloon observations of temporal and spatial fluctuations in stratospheric conductivity

The first campaign of the Polar Patrol Balloon (PPB) experiment (1st-PPB) was carried out at Syowa Station in Antarctica during 1990–1991 and 1992–1993. Based on the results of the 1st-PPB experiment, the next campaign (2nd-PPB) was carried out in the austral summer of 2002–2003. This paper will present stratospheric conductivity results from the 2nd-PPB experiment. In that experiment, three balloons were launched for the purpose of upper atmosphere physics observation (three balloons). Payloads of these three flights were identical with each other, and were launched as close together in time as allowed by weather conditions to constitute a cluster of balloons during their flights. Such a “Balloon Cluster” is suitable to observe temporal evolution and spatial distribution of phenomena in the ionospheric regions and boundaries that the balloons traversed during their circumpolar trajectory. More than 20 days of simultaneous fair weather 3-axis electric field and stratospheric conductivity data were obtained at geomagnetic latitudes ranging from sub-auroral to the polar cap. Balloon separation varied from ∼60 to >1000 km. This paper will present stratospheric conductivity observations with emphasis on the temporal and spatial variations that were observed.     

VLBI observations to the APOD satellite

The APOD (Atmospheric density detection and Precise Orbit Determination) is the first LEO (Low Earth Orbit) satellite in orbit co-located with a dual-frequency GNSS (GPS/BD) receiver, an SLR reflector, and a VLBI X/S dual band beacon. From the overlap statistics between consecutive solution arcs and the independent validation by SLR measurements, the orbit position deviation was below 10?cm before the on-board GNSS receiver got partially operational. In this paper, the focus is on the VLBI observations to the LEO satellite from multiple geodetic VLBI radio telescopes, since this is the first implementation of a dedicated VLBI transmitter in low Earth orbit. The practical problems of tracking a fast moving spacecraft with current VLBI ground infrastructure were solved and strong interferometric fringes were obtained by cross-correlation of APOD carrier and DOR (Differential One-way Ranging) signals. The precision in X-band time delay derived from 0.1?s integration time of the correlator output is on the level of 0.1?ns. The APOD observations demonstrate encouraging prospects of co-location of multiple space geodetic techniques in space, as a first prototype.     

Investigation on the MLT tidal variability during September 2019 minor sudden stratospheric warming

Tidal variability in the mesosphere and lower thermosphere (MLT) during September 2019 Southern hemisphere minor sudden stratospheric warming (SSW) is investigated utilizing ground-based meteor radar wind observations from the equatorial, extratropical, middle, and high latitude stations and global reanalysis dataset. The polar warming is found to move from the mesosphere to the stratosphere until the peak warming day (PWD) of the SSW. The diurnal and semidiurnal tides at individual observational sites do not exhibit any consistent response during the observational interval, but a notable and consistent variability in some specific zonal wavenumber components, i. e., DW1 (migrating diurnal tide), DE3 (nonmigrating eastward wavenumber 3 diurnal tide), and SW2 (migrating semidiurnal tide) is found in the global reanalysis dataset. Incidentally, the warming event occurs during Spring equinox when a dominant seasonal change in the tidal activities generally takes place and hence seasonal variability is also looked into while identifying the SSW impact during the observational interval. It is found that the seasonal broad changes in the DW1, DE3, and SW2 amplitudes can be explained by the variability in the tidal sources, i.e., water vapor, convective activity, ozone, etc during the observational period. However, the extracted short-term variability in the global tidal modes on removing seasonal trend reveals noticeable response in connection with the warming event. The deseasoned amplitude of the DW1 significantly enhances around the PWD at most of the present latitudes. The deseasoned DE3 amplitude responds significantly in the middle atmosphere at low latitudes during the warming phase. The deseasoned SW2 exhibit clear enhancement around the PWD at all the latitudes. However, the deseasoned tidal features do not seem to correlate well with that of the source species unlike the seasonal ones that imply involvement of complex processes during the warming event, seeking further future investigations in this regard.     

Verification of IRI plasma temperature at great altitude by satellite data

Electron temperature data obtained aboard two satellites are compared with the IRI model. Our comparison may serve as an input to a future version of IRI. HINOTORI data show IRI90 to predict night time T_e quite well with the exception of a few peculiar phenomena, in particular a morning overshoot at height around 600 km and anomalous T_e observations of AKEBONO for the first time allowed to extend reliably the temperature profile up to − 8000km. This profile clearly depends on local time at all invariant latitudes. The data suggest strong influence of solar activity on electron temperature.     

Simultaneous observations of Pc 1 micropulsation activity and stratospheric electrodynamic perturbations on 27 January 2003

The 2nd Polar Patrol Balloon campaign (2nd-PPB) was carried out at Syowa Station in Antarctica during 2002–2003. Identical stratospheric balloon payloads were launched as close together in time as allowed by weather conditions to constitute a cluster of balloons during their flights. A very pronounced negative ion conductivity enhancement was observed at 32 km in the stratosphere below the auroral zone on 27 January 2003 from 1500 to 2200 UT. During this event, the conductivity doubled for an interval of about 7 h. This perturbation was associated with an extensive Pc 1 or Pi 1 wave event that was observed by several Antarctic ground stations, balloon PPB 10, and the Polar spacecraft. No appreciable X-ray precipitation was observed in association with this event, which would point to >60 Mev proton precipitation as a possible magnetosphere–stratosphere coupling mechanism responsible for the conductivity enhancement. Such precipitation is consistent with the wave data. During the latter half of the event, E_z was briefly positive. There was a tropospheric Southern Ocean storm system underneath the balloon during this interval. If the event was associated with this storm system and not energetic proton precipitation, the observations imply an electrified Southern Ocean storm and major perturbations in stratospheric conductivity driven by a tropospheric disturbance. This event represents a poorly understood source for global circuit current. Precipitating energetic proton data from Akebono and NOAA POES spacecraft show significant >16 MeV precipitation was occurring at the location of PPB 8 but not PPB 10, suggesting that proton precipitation was, in fact, the responsible coupling mechanism.     

A glimpse at the GOCE satellite gravity gradient observations

Since 30 September 2009, following the launch and in-orbit testing of the most sophisticated gravity mission ever built, the European Space Agency (ESA) GOCE satellite is in ‘measurement mode’, providing continuous time series of satellite gravity gradient (SGG) observations and GPS satellite-to-satellite tracking (SST) observations. The availability of GPS SST observations allows the precise reconstruction of the GOCE position and thus the precise geolocation of the SGG observations. The SGG observations are based on the differences between observations taken by pairs of accelerometers, which need to be corrected first by applying a so-called calibration matrix and second by subtracting rotational terms (centrifugal and angular accelerations).     

Trace constituents measurements deduced from spectrometric observations on-board spacelab

The observation of infrared absorption lines by means of a grille spectrometer on board Spacelab 1 allows the determination of Co₂ and CO in the low thermosphere and in the middle atmosphere. Equal abundances of CO and CO₂ are found at 115 ± 5 km altitude. CO₂ is observed to depart from its homospheric volume mixing ratio near 100 km, dropping by a factor of 10,15 km higher. The CO largest number density is observed near 70 km altitude, close to the H Lyman alpha photoproduction peak.The analysis of one run dedicated to the observation of water vapor shows a middle atmospheric mixing ratio of this species within the limits : 3 to 8 ppmv up to 70 km altitude, with the indication of an increase from 30 to 50 km altitude. The H₂O mixing ratio drops very rapidly above 70 km.The comparison of the results from strong and weak H₂O and CO₂ lines shows the need to refine the line profile model.     

Recent advances in understanding stratospheric dynamics and transport processes: Application of satellite data to their interpretation

The present paper discusses the use of the transformed Eulerian (or “residual”) mean-flow formulation, the Eliassen-Palm flux, and Ertel's potential vorticity to provide an increased understanding of wave, mean-flow interactions, and constituent transport processes in the stratosphere. Temperature and ozone data retrieved from radiance profiles obtained by the LIMS instrument on the Nimbus 7 satellite are utilized in conjunction with these theoretical concepts for the interpretation of phenomena that occurred during the major and minor warmings of January-February 1979. The results illustrate the insight provided by these concepts and demonstrate that useful diagnostic quantities can be derived from global satellite temperature fields.     

On the adjust of minor constituents density in middle atmosphere during solar proton events

Profiles of O₃ partial pressure and of other minor atmospheric constituents (NO, NO₂, HCL, HF and H₂O), observed in the middle atmosphere during Solar proton events (20.04.1998; 05.04.2000), were analysed. Conclusions were drawn that under SCR impact a short-term O₃ partial pressure increase and destruction of some freon constituents took place.     

Energetic particle fluxes data base of “CORONAS-I” satellite observations

The data base DB SCR uses data obtained by the SCR instrument package on the CORONAS-I satellite. DB SCR contains information about fluxes of relativistic electrons (0.5–124 MeV), protons (1–300 MeV), nuclei (1–19 MeV/nucl) and γ-radiation (0.1–7 MeV) in the low altitude region (500 km). The time resolution of the data is 2.5 s. Magnetic field parameters (B, magnetic latitude and longitude), L-shell and local times (LT and MLT) are included in DB SCR. Since all parameters are equivalents it is possible to perform the multidimensional analysis for any set of DB SCR parameters. The additional DB SCR software packages may be used to develop different semi-empirical models.     

Validation of the stratospheric sounding unit

The Stratospheric Sounding Unit (SSU) is part of the TOVS (TIROS Operational Vertical Sounder) on NOAA operational meteorological satellites. SSU measurements can be validated by comparison with temperature measurements from colocated rocket sondes. Systematic differences are found which vary with rocket station and sonde and are a function of height. However, these measurements are not adequate to define the performance of individual SSUs to a precision which would allow the observations from different SSUs to be combined in the study of diurnal and semidiurnal tides and of long term trends in stratospheric temperature. Instead this is achieved by detailed radiometric and spectroscopic investigation of each individual SSU, both prior to launch and during its operational life. Using the techniques descirbed, it is demonstrated that measurements from different SSUs can be combined with a relative error of less than 0.2K in equivalent brightness temperature.     

IR-spectroscopy of ionosphere from stratospheric balloons

The radiation spectra of the ionosphere in the 4–5 μm region have been determined from stratospheric balloons by means of the specially elaborated method of the registration of angular and spectral distribution of the radiation. The radiation bands of 4.4 μm and 4.8 μm which have 0.1–0.2 erg cm^?2 sr^?1s^?1. brightness obtained in two flights, are identified with the vibration-rotation transitions of the ion NO⁺ (0 - 1) and the molecules N¹⁴N¹⁵ (0 - 1) and CO (0 - 1) and (3 - 2) from altitudes between 120 and 500 km.     

Mass spectrometric measurements of stratospheric ions

Recent in situ measurements with balloon borne quadrupole mass spectrometers, between 20 and 45 km altitude, are reviewed and discussed.The major stratospheric positive ions observed are proton hydrates [H⁺(H₂O)_n] and non proton hydrates of the form H⁺X_m(H₂O)₂. The data analysis allows a derivation of the vertical mixing ratio profile of X (most probably CH₃CN), which is compared with recent model calculations. From negative ion composition data, showing the presence of NO₃^? and HSO₄^? cluster ions, the density of sulfuric acid in the stratosphere is deduced. The implications of these findings on our understanding of the sulfur chemistry is briefly treated.Finally some other aspects such as contamination, cluster break up and the use of stratospheric ion mass spectra for determination of thermochemical data and other minor constituents are discussed.     

An examination of a technique for estimating the longwave radiation budget from satellite radiance observations

Intercomparisons of the zonally averaged outgoing longwave fluxes estimated from 10 μm radiance observations on NOAA polar orbiters and flat plate observations on the Nimbus 6 ERB experiment have shown the NOAA estimates to be higher than the ERB measurements. Our analysis shows that the operational technique systematically overestimates calculated fluxes for middle and high cloud conditions. A different radiative transfer model and new assumptions concerning clouds reduce the NOAA-ERB flux difference by approximately 35%.     

Up-to-date observations of space energetic particles made by the Chinese satellite Fengyun-1 (B).

This paper presents the observational results of space energetic particles obtained by the Cosmic Ray Composition Monitor (CRCM) onboard the Chinese satellite, Fengyun-1(B). These results, including those of a few solar proton events, the geomagnetically trapped particles and the anomalous cosmic ray components, were obtained from 3 September 1990 to 15 February 1991. The observed elements include H, He, C, N, O and Fe of energies from 4-23 MeV/u. It was found that the proton fluxes of the inner Radiation Belt (IRB) increased obviously during the period of solar proton event (SPE). A few kinds of heavy ions (Z > or = 6) were also detected in the IRB. As to the anomalous cosmic ray component (ACRC), in addition to C, N and O, anomalous iron particles were also recorded.     

The subauroral electron density trough: Comparison between satellite observations and IRI-2007 model estimates

We compare electron density predictions of the International Reference Ionosphere (IRI-2007) model with in situ measurements of the satellites CHAMP and GRACE for the years from 2005 to 2010 over the subauroral regions. The electron density between 58° and 68° Mlat are considered. The trough region Ne peaks during local summers and attain the valley during local winter. Around −100°E and 60°E, two larger electron density sectors features can be seen in both hemispheres during all three seasons, which attributed to the electron extending from middle latitude to trough region. From 2005 to the beginning of 2010, the model overestimates the trough region Ne by 20% on average and the decrease of Ne in this region can also be seen during the last solar minimum. In the southern hemisphere, the model prediction shows quite well consistence with the observation during all three seasons while the huge difference between observations and model estimation implies that the IRI-2007 model needs significant improvement to predict better the trough region in northern hemisphere.     

Backstepping sliding-mode control of stratospheric airships using disturbance-observer

In the presence of unknown disturbances and model parameter uncertainties, this paper develop a nonlinear backstepping sliding-mode controller (BSMC) for trajectory tracking control of a stratospheric airship using a disturbance-observer (DO). Compared with the conventional sliding mode surface (SMS) constructed by a linear combination of the errors, the new SMS manifold is selected as the last back-step error to improve independence of the adjustment of the controller gains. Furthermore, a nonlinear disturbance-observer is designed to process unknown disturbance inputs and improve the BSMC performances. The closed-loop system of trajectory tracking control plant is proved to be globally asymptotically stable by using Lyapunov theory. By comparing with traditional backstepping control and SMC design, the results obtained demonstrate the capacity of the airship to execute a realistic trajectory tracking mission, even in the presence of unknown disturbances, and aerodynamic coefficient uncertainties.     

Possible influence of solar radiation variability on the stratospheric temperature

Using daily temperature data available from radio-sonde measurements over Barajas (Madrid), La Coruña and Palma de Mallorca stations, for the time span 1971–1982 and an altitude range 100-30 mb, a study is made comparing temperatures at differents levels with the 10.7 cm flux in order to check whether radiation variability must be included in lower stratospheric models. At the latitude studied, stratospheric temperatures are uninfluenced by sudden warming phenomena avoiding difficulties of masking found in previous studies.     

December 2006 solar extreme events and their influence on the near-Earth space environment: “Universitetskiy-Tatiana” satellite observations

The Russian microsatellite “Universitetskiy-Tatiana” was launched on Jan. 20, 2005 and was both a scientific and educational mission. Its two main aims were declared as: (1) monitoring of the energetic particles dynamics in the near-Earth space environment after solar events and during quiet times, (2) educational activities based on experimental data obtained from the spacecraft. In this paper observations acquired during Dec. 5–16, 2006, known as “Solar Extreme Events 2006”, were analyzed. The “Universitetskiy-Tatiana” microsatellite orbit permits one to measure both solar energetic particle dynamics, variations of the boundary of solar particle penetration, as well as relativistic and sub-relativistic electrons of the Earth’s outer radiation belt during and after magnetic storms. Both relativistic electrons of the Earth’s outer radiation and solar energetic particles are an important source of radiation damage in near-Earth space. Therefore, the presented experimental results demonstrate the successful application of a small educational spacecraft both for scientific and educational programs.