The remote sensing complex for monitoring the atmospheric surface layer includes a temperature and wind profilers, a radiometer for the total vapor content and a weather station. The complex provides continuous measurement of vertical profiles of air temperature, wind speed and direction at heights up to 1000 m with a vertical resolution of 10 to 100 m and a measurement period of 10 minutes. Surface parameters – air temperature and humidity, pressure, type and intensity of precipitation – are also recorded. The complex is designed for studying processes in the surface layer, the formation and forecasting of dangerous phenomena.
Total vapor content of the atmosphere is a primary factor in diagnosing thermal conditions and determining areas of possible aircraft icing. This study for the period from October 1, 2018 to March 31, 2020, is based the AV-6 electronic weather logs and crew weather reports (PIREP). The paper considers the ranges of the total vapor content Q and total vapor content during icing Qi for the seasons most favorable for the icing occurance. Icing is observed at values of the total vapor content Qi from 0.3 to 1.5 g/cm2.
Seasonal characteristics of the distribution of the total vapor content of the atmosphere and the characteristics of cloudiness and wind in the area of St. Petersburg airport are described for the period from October 1, 2018 to September 30, 2020. The St. Petersburg airport is subject to humid sea air from the Atlantic, which is most significant in the autumn and winter periods. The intensity of atmospheric circulation decreases in summer. The summer period has a peak in the distribution of the total vapor content of the atmosphere and the height of the cloud base shifted to higher values. On the contrary, the distribution of wind speed in the area of the Pulkovo airfield practically does not change depending on the season.
The polar vortex strengthening leads not only to a temperature decrease in the lower stratosphere, but also to its increase in the upper stratosphere inside the vortex. Over the Antarctic, this dependence is observed from autumn to spring: in the upper stratosphere high temperatures are observed inside the polar vortex, and low temperatures occur outside, especially in spring. Over the Arctic, a temperature increase in the upper Arctic stratosphere is observed under conditions of the strengthening of the northern polar vortex. Temperature variations in the upper polar stratosphere are determined by the ozone concentration and depend on the dynamics of the polar vortex: with a decrease in the ozone content inside the strong vortex in the upper stratosphere, a temperature increase is observed.
Dynamics and statistics of the total content of supercooled water were studied using real-time radiometry methods in the period from November 2016 to January 2017, when aircraft icing was observed at the Tomsk airport. The histogram of the total water content is single-modal and shifted to the left; and the temperature histogram is bimodal. The minimum and maximum values of the total water content are 0 kg/m2 and 1.5 kg/m2 , respectively; and the minimum and maximum temperatures are – 19° C and 0° C. The bimodality of the temperature histogram represents two combined processes that occur during the supercooled water droplets formation in the considered period. The first process is connected with the change of the season of the year, the second - with the arrival of warm and moist air masses to the cold territory.
KEYWORDS: Calibration, Raman spectroscopy, LIDAR, Temperature metrology, Troposphere, Solids, Climatology, High temperature raman spectroscopy, Data modeling, Signal detection
We present a temporal stability study of the calibration coefficients of two nonlinear calibration functions which are used for temperature retrievals in the pure rotational Raman (PRR) lidar technique. These functions represent the special cases of the general calibration function that takes into account the collisional broadening of all N2 and O2 PRR lines in the troposphere. The coefficients stability is studied on the examples of vertical tropospheric temperature profiles (3–9 km) retrieved on 1, 6, 7, and 8 April 2015. The temperature profiles were retrieved from nighttime lidar measurements made in Tomsk (56.48° N, 85.05° E, Western Siberia, Russia) using the IMCES PRR lidar. The lidar was developed in the Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS). The validity of usage of the calibration coefficients averaged over some period of monitoring for temperature profile retrievals is discussed.
It is shown that the maximum frequency distribution of icing pireps at the Novosibirsk International Airport in January 2015 was accounted for the height layer from 0 to 1 km. With the increasing height aircraft icing is less common and, starting at 5 km, it is not recorded. Maximum frequency distribution for the Tomsk International Airport in winter 2014 – 2015 was also recorded at these altitudes, but it is not so pronounced, and from 4 km icing has not been reported. Altitude dependencies of frequency distribution for Novosibirsk and Tomsk airports are significantly different from that in the continental United States [1] and from the results published in [2].
We present the general calibration function for temperature retrievals in the cloud-free troposphere using pure rotational Raman (PRR) lidars under the condition of the laser-beam receiver-field-of-view complete overlap. The function is derived within the framework of the semiclassical theory and takes account of the broadened by collision effects elastic backscattered signal leakage into the nearest (to the laser line) lidar PRR channel. The two simplest nonlinear special cases of the general calibration function are considered to be applied in the temperature retrieval algorithm. The vertical temperature profiles retrieved from nighttime lidar measurements in Tomsk (56.48°N, 85.05°E), on October 2, 2014, are given as an example. The measurements were performed using a PRR lidar designed in Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS) for lower-atmosphere temperature-profile retrievals.
Development of KrF laser system for lidar designed for detection of the compound molecules containing a nitric
oxide is presented. The system consists of the master oscillator and the amplifier operating at pulse repetition rate up to
100 Hz. Laser radiation having energy up to 0.2 J and bandwidth of 2 pm is smoothly tuned in a spectral range of 247.6-249.5 nm.
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