Mikhail Khaplanov

Hygrosonde-A direct measurement of water vapor in the stratosphere and mesosphere

A rocket-borne optical hygrometer for night time in situ measurements of the middle atmospheric water content was successfully launched from Esrange, Sweden, in December 1994. Utilizing the OH photofragment fluorescence technique, the instrument takes measurements in an undisturbed volume outside the rocket shock front. A profile of water vapor was obtained between 17 and 70 km. The stratospheric mixing ratio increases from 3.5 ppmv near 20 km to around 6 ppmv above 45 km, while the mesospheric profile shows a strongly stratified structure. The results are discussed in terms of horizontal transport and compared to recently published model results on the redistribution of water vapor in the winter polar mesosphere.

Combination of Lidar and Model Data for Studying Deep Gravity Wave Propagation

The paper presents a feasible method to complement ground-based middle atmospheric Rayleigh lidar temperature observations with numerical simulations in the lower stratosphere and troposphere to study gravity waves. Validated mesoscale numerical simulations are utilized to complement the temperature below 30-km altitude. For this purpose, high-temporal-resolution output of the numerical results was interpolated on the position of the lidar in the lee of the Scandinavian mountain range. Two wintertime cases of orographically induced gravity waves are analyzed. Wave parameters are derived using a wavelet analysis of the combined dataset throughout the entire altitude range from the troposphere to the mesosphere. Although similar in the tropospheric forcings, both cases differ in vertical propagation. The combined dataset reveals stratospheric wave breaking for one case, whereas the mountain waves in the other case could propagate up to about 40-km altitude. The lidar observations reveal an interaction of the vertically propagating gravity waves with the stratopause, leading to a stratopause descent in both cases.

First UV satellite observations of mesospheric water vapor

We report the first UV satellite observations of mesospheric water vapor. The measurements are of nonthermal OH prompt emission between 300–330 nm produced directly from the photodissociation of wa ...

O-2 density and temperature profiles retrieving from direct solar Lyman-alpha radiation measurements

The resonance transition 2P-2S of the atomic hydrogen (Lyman-alpha emission) is the strongest and most conspicuous feature in the solar EUV spectrum. The Lyman-alpha radiation transfer depends on the resonance scattering from the hydrogen atoms in the atmosphere and on the O2 absorption. Since the Lyman-alpha extinction in the atmosphere is a measure for the column density of the oxygen molecules, the atmospheric O2 density and temperature profiles can be calculated thereof. A detector of solar Lyman-alpha radiation was manufactured in the Stara Zagora Department of the Solar-Terrestrial Influences Laboratory (STIL). Its basic part is an ionization camera, filled in with NO. A 60 V power supply is applied to the chamber. The produced photoelectric current from the sensor is fed to a two-channel amplifier, providing analog signal. The characteristics of the Lyman-alpha detector were studied. It passed successfully all tests and the results showed that the so-designed instrument could be used in rocket experiments to measure the Lymanalpha flux. From the measurements of the detector, the Lyman-alpha vertical profile can be obtained. Programs are created to compute the O2 density, atmospheric power and temperature profiles based on Lymanalpha data. The detector design appertained to ASLAF project (Attenuation of the Solar Lyman-Alpha Flux), a scientific cooperation between STIL—Bul.Acad.Sci., Stara Zagora Department and the Atmospheric Physics Group at the Department of Meteorology (MISU), Stockholm University, Sweden. The joint project was part of the rocket experiment HotPay I, in the ALOMAR eARI Project, EU’s 6th Framework Programme, Andøya Rocket Range, Andenes, Norway. The project is partly financed by the Bulgarian Ministry of Science and Education.

Optical fluorescent hygrometer for water vapor low concentration measurements

An optical hygrometer has been developed to make night-time measurements of water vapor in the upper atmosphere using the technique of photofragment fluorescence. Hygrometer uses the fluoroscence at wavelengths near 310 nm of excited OH molecules produced in the photodissociation of water molecules by UV radiation with hydrogen lamp (121.6 nm). A coaxial optical scheme is used. A compact hydrogen lamp is aligned along the axis of the instrument, inside the annular fast focusing optics. It provides the effective convergence of fluorescence from a large angle and thus increase the sensitivity of this method. The modulation of the hydrogen lamp with the frequency 1 kHz is used. Specially designed laboratory technique for calibration of the hygrometer is described. Total weight of the optical hygrometer is about 3 kg. It can be easily integrated with the Vaisala RS-80 radio sonde. This allows us to obtain reliable real-time data on temperature, pressure, and water vapor concentrations in the upper troposphere and stratosphere.

Atmospheric Band Fitting Coefficients Derived from Self-Consistent Rocket-Borne Experiment

16 Based on self-consistent rocket-borne measurements of temperature, densities of atomic 17 oxygen and neutral air, and volume emission of the Atmospheric Band (762 nm) we 18 examined the one-step and two-step excitation mechanism of OO2�bbΣgg� for night-time 19 conditions. Following McDade et al. (1986), we derived the empirical fitting coefficients, 20 which parameterize the Atmospheric Band emission OO2�bbΣgg − XXΣgg�(0,0). This allows to 21 derive atomic oxygen concentration from night-time observations of Atmospheric Band 22 emission OO2�bbΣgg − XXΣgg�(0,0). The derived empirical parameters can also be utilised for 23 Atmospheric Band modelling. Additionally, we derived fit function and corresponding 24 coefficients for combined (oneand two-step) mechanism. Simultaneous common volume 25