The report presents data from lidar observations of upper-level clouds in Tomsk in 2011-2017. Observations were carried out using a LOSA-S multi-wave lidar, simultaneously recording elastic scattering signals (355 and 532 nm) and Raman scattering signals in the vibrational Q-band (387 and 607 nm). Examples of lidar records are given, the method for determining the optical thickness of the cloud layer and possible sources of calculation errors are considered.

The spatial structure of atmospheric aerosol over Baikal in summer is studied on a regular basis with the use of ground-based LOSA-M2 lidar measurements at the Boyarsky scientific station of the Institute of Physical Material Science, Siberian Branch, Russian Academy of Sciences (51.83 degrees N, 106.06 degrees E, 456 m a.s.l.), Republic of Buryatia, Russia. The lake is located in a basin surrounded by mountain ranges on all side; its water volume is large. The lidar data are analysed along with the regional meteorological situation and meteorological parameters of the atmosphere. The daily dynamics of aerosol distribution over the atmospheric is examined for the period from 2015 to 2023 accounting the effect of different air masses in the region. Three main typical air circulation types are identified for the coastal zone of southern Baikal in summer, which determine the atmospheric aerosol generation and transport. The first and most common type relates to breeze circulation, where the main changes in the spatial structure of aerosol occur in the 2-3-km layer and are determined by changes in the transport direction within a breeze cell during the day. The main feature of this type is a decrease in the altitude of an air layer which contains most of aerosol in the lower atmosphere up to 1 km. The second type refers to southwestern transport under the presence of an anticyclone over the region. The maximal altitude of the aerosol layers attains 7 km in this case. The most complex and dynamic changes in the daily spatial structure of atmospheric aerosol occurred under transport of cyclones and associated atmospheric fronts over Lake Baikal. Under this third type, the altitude of the aerosol layers decreases throughout the day within the altitude range from the surface to 3-4 km.

Рассмотрены результаты самолетных лидарных измерений пространственного распределения концентрации фитопланктона в поверхностных водах Карского моря. Содержание фитопланктона определяется методом лазерно-индуцируемой флуоресценции фотосинтезирующего пигмента – хлорофилла «а». Интенсивность сигналов флуоресценции нормировалась на интенсивность сигналов комбинационного рассеяния излучения воды. Результаты пространственного распределения нормированной интенсивности флуоресценции получены для трех участков Карского моря. Для двух участков моря пространственное распределение фитопланктона достаточно однородное с коэффициентами вариации меньше 15%. Третий участок характеризуется мощным влиянием материкового речного стока, что проявляется в наличие фронтальных зон, где коэффициент вариации распределения достигает 40%. Преимущественный вклад в эти вариации значений нормированной интенсивности флуоресценции вносит изменчивость сигналов комбинационного рассеяния в воде. This paper presents the results of aircraft lidar measurements of the spatial distribution of phytoplankton concentration in the surface waters of the Kara Sea. The phytoplankton content is determined using the laser-induced fluorescence method of the photosynthetic pigment - chlorophyll "a". The intensity of fluorescence signals is normalized to the intensity of the combined scattering signals of water radiation. Results of the spatial distribution of normalized fluorescence intensity are obtained for three sections of the Kara Sea. For two sections, the spatial distribution of phytoplankton is quite homogeneous with variation coefficients of less than 15%. The third section is characterized by a strong influence of continental river runoff, manifested in the presence of frontal zones, where the variation coefficient of the distribution reaches 40%. The predominant contribution to these variations in normalized fluorescence intensity is made by the variability of the combined scattering signals in the water.

В работе приведены результаты лазерного зондирования атмосферы над акваторией озера Байкал, полученные в ходе регулярных летних экспедиций. Анализ накопленных с использованием лидаров серии «ЛОЗА» данных, совместно с информацией об изменении метеопараметров атмосферы во время экспериментов, позволил исследовать пространственно-временную изменчивость вертикальной структуры аэрозоля в различных атмосферных условиях. The paper presents the results of laser sensing of the atmosphere over the water area of Lake Baikal, obtained during regular summer expeditions. The analysis of the data accumulated using lidars of the LOZA series, together with information on changes in atmospheric meteorological parameters during experiments, made it possible to study the spatiotemporal variability of the vertical structure of the aerosol in various atmospheric conditions. laser sounding of the atmosphere, Lake Baikal water area, vertical structure of aerosol, spatiotemporal variability

В работе рассмотрены особенности оценивания коэффициентов ослабления, обратного рассеяния, лидарного отношения по данным одновременного зондировании на длинах волн: 532 нм (упругое рассеяние, УР); 607 нм (колебательно-вращательное комбинационное рассеяние, КР); 530 нм (чисто вращательное КР). Основное внимание уделяется погрешностям восстановления параметров двухкомпонентной (молекулы + аэрозоль) и трехкомпонентной (молекулы + аэрозоль + облако) среды по данным зондирования на юго-западном побережье оз. Байкал в августе 2023 года. The paper considers the features of estimating the coefficients of attenuation, inverse scattering, lidar ratio according to simultaneous sensing data at wavelengths: 532 nm (elastic scattering, UR); 607 nm (vibrational-rotational raman scattering, Raman); 530 nm (purely rotational Raman). The main attention is paid to the errors in the reconstruction of the parameters of a two-component (molecule + aerosol) and three-component (molecule + aerosol + cloud) medium according to the sounding data on the southwestern coast of the lake. Baikal in August 2023.

В работе приведены результаты лазерного зондирования атмосферы над акваторией оз. Байкал в летней экспедиции 2023 г. На основе данных полученных с использованием лидара «ЛОЗА-А2», исследована пространственно-временная изменчивость вертикальной структуры аэрозольных полей. Это позволяет выявить особенности формирования и переноса атмосферного аэрозоля в данном регионе. The paper presents the results of laser sounding of the atmosphere over the water area of Lake Baikal during the summer expedition of 2023. Based on the data obtained using the “LOZA-A2” lidar, the spatiotemporal variability of the vertical structure of aerosol fields is investigated. This allows us to reveal the features of the formation and transport of atmospheric aerosols in this region.

In this paper, we present the results of complex experimental studies of gas admixtures and the vertical structure of aerosol in the atmosphere over Lake Baikal in September 2021, performed onboard research vessel (RV) Akademik V.A. Koptyug. Measurements of gas admixtures in the near-water atmospheric layer were carried out using local control means, i.e., chemiluminescent gas analyzers. The aerosol fields were sensed using a multifrequency polarization aerosol-Raman lidar LOSA-A2. Compared to previous expeditions, in 2021, we recorded the low concentrations of gas admixtures and aerosols, close to the background ones. The analysis showed that the main contributions to the atmospheric pollution were from local sources located near the coastal zone of the lake.

Представлены результаты синхронных лидарных наблюдений переноса аэрозольных полей атмосферы над оз. Байкал в летней экспедиции 2018 г. Эксперимент проводился с использованием двух лидаров, один из которых располагался на судне, а второй - на стационаре, на удалении 732 м от судна. На основе корреляционного анализа полученных данных сделаны оценки времени переноса атмосферных аэрозольных неоднородностей между точками наблюдений на разных высотах над горной котловиной. Выявлено, что для высотного диапазона 100-350 м время переноса составляет 5 мин 20 с, для 1250-1500 м - 7 мин 12 с, для 2100-2500 м - 5 мин 20 с и для диапазона 4200-4300 м - 6 мин 24 с. Подобное неравномерное высотное распределение времени переноса аэрозольных объектов обусловлено сложным механизмом циркуляции воздушных потоков в горной котловине. The results of synchronous lidar observations of the transfer of atmospheric aerosol fields over Lake Baikal during the summer expedition of 2018 are presented. The experiment was carried out using two lidars, one of which was located on a ship, and the second, at a distance of 732 m at a stationary station. Based on the correlation analysis of the lidar data, the transfer time of atmospheric aerosol heterogeneities between observation points at different altitudes above the mountain basin is estimated. It is found that the transfer time is 5 min 20 s for the altitude range 100-350 m, 7 min 12 s for 1250-1500 m, 5 min 20 s for 2100-2500 m, and 6 min 24 s for the range 4200-4300 m. Such uneven altitude distribution of the transfer time of aerosol objects is due to the complex air flow circulation in the mountain basin.

The results of the modernization of the mobile aerosol Raman lidar LOZA-A2 are presented. Lidar measures purely rotational Raman scattering signals simultaneously with measurements of the vibrational component of spontaneous Raman scattering of lidar signals. The technique for interpreting Raman lidar sensing data is considered. Data are obtained from simultaneous measurements of vibrational–rotational and purely rotational Raman scattering in atmospheric sensing over the Lake Baikal. The results are presented from retrieving the vertical profiles of the optical characteristics of the atmosphere at a wavelength of 532 nm using these data.

The paper presents the results of laser sounding of the atmosphere over of Lake Baikal in the summer ship expedition in 2022. Based on the data obtained using the LOSA-A2 lidar, the spatiotemporal variability of the vertical structure of aerosol fields was studied. This makes it possible to reveal the features of the formation and transport of atmospheric aerosol in a given region. Based on the results of the studies, it was found that during the expedition, either background values of the aerosol content in the atmosphere or a weak filling of the lower troposphere with aerosol due to local sources of pollution were observed.

The results of long-term lidar studies of the peculiarities of the vertical structure of atmospheric aerosols over Lake Baikal are presented. The paper provides an analysis of data obtained over the period from 2010 to 2022. The studies were carried out under both the background conditions and the extreme natural conditions associated with severe wildfires in Siberia. The parameters of the lidars used in regular summer expeditions to Lake Baikal are briefly described. The data analysis shows that the vertical structure of the aerosol in the lower troposphere up to 2000 m above Baikal in summer is often a stable structure of several aerosol layers tens to hundreds of meters thick. There can be no mixing of layers because the water in the lake is very cold and the aerosol does not rise to higher layers while the air is warming up during the day. The difference is shown between the spatiotemporal structures of aerosol plumes from local wildfires within the lake area and from distant sources. The Angstrom parameter and the aerosol optical depth are calculated for different atmospheric conditions: ηβ = 1.57 ± 0.16 and τ = 0.09 for background conditions; ηβ = 1.41 ± 0.07 and τ = 0.64 for the cases of the observation of smoke aerosol from distant wildfires; and ηβ = 1.05 ± 0.08 and τ = 0.25 for the cases of the observation of smoke aerosol from nearby wildfires.

The paper briefly describes some features of the formation of aerosol fields in the water area of Lake Baikal in summer. The experimental data were collected during long-term expeditionary studies on the southeastern coast of the lake, at the Boyarsky station (51.84° N, 106.06° E), with the use of a LOSA-M2 lidar designed at the Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (IAO SB RAS). A complex, layered, vertical structure of the atmospheric aerosol in the mountain basin is revealed. This is caused by peculiarities of the temperature and wind regimes at this site. The general pattern of the calculated autocorrelation matrices shows a good correlation in the range of 0–1000 m (the correlation coefficient is greater than 0.5). The aerosol layers in the lower-kilometer layer are closely related to each other and have a common origin.

A procedure is proposed for determining the aerosol microphysical characteristics, the complex refractive index m = mreal + i*mimage and the bimodal size distribution function U(r) of spherical particles, based on laser sensing data at the wavelengths within 355-1064 nm. In parallel with this, the possibilities of an additional Raman scattering channel in the IR wavelength range are considered. The main attention is paid to a separate fraction-wise retrieval of m + U(r) for weakly absorbing particles, mimage < 0.015, when mfine ≠ mcoarse holds. The algorithms are tested for a fixed value mfine = 1.50+i*0.01 and varied values of mcoarse = 1.40+i*0.0001 or 1.60+i*0.0001. In order to include the influence of the contribution from the particles of different fractions into the total concentration, 462 empirical models of U(r) are used.

In the period from 2010 to 2021, in the village of Boyarsky on the eastern coast of Baikal Lake, studies were carried out on the vertical structure of aerosol fields in the troposphere. The measurements were carried out using the LOSA-M2 aerosol-Raman lidar in the summer (July - August). A total of 93 cycles of daily observations were carried out during this period. The report presents typical patterns of transformation of aerosol layers under various synoptic conditions. Particular attention is paid in the report to the relationship between the structure of the boundary layer and the direction of movement of air masses. With a southeasterly wind prevailing at the observation site and directed along the coast, a characteristic diurnal dynamics of the boundary layer is observed with the development of a mixing layer during daytime heating of the surface. When air masses formed above the cold surface of the lake are brought in, a layered structure without pronounced updrafts prevails.

Исследование связано с возможностями и ограничениями различных лидарных систем при восстановлении микрофизических параметров аэрозоля. В настоящей работе рассмотрены особенности совместного определения комплексного показателя преломления и функции распределения сферических частиц по размерам по данным лазерного зондирования на длинах волн 355-1064 нм. Основное внимание уделяется погрешностям искомых параметров для крупных частиц.

В работе приведены результаты лидарных наблюдений атмосферы над акваторией оз. Байкал. Комплексные корабельные исследования, с использованием научно-исследовательского судна (НИС) «Академик В.А. Коптюг», проводятся ежегодно, с использованием лидара «ЛОЗА-А2», а также локальных средств (газоанализаторов). Дополнительно привлекаются спутниковые данные и информация о метеопараметрах атмосферы во время экспериментов. Маршрут судна проходит по всему озеру. Проводится анализ для выявления основных источников загрязнения атмосферы в Байкальском регионе.

В настоящей работе рассмотрены особенности оценки коэффициентов ослабления и обратного рассеяния света при зондировании атмосферы на длинах волн: 532 нм (упругое рассеяние, УР); 607 нм (колебательно-вращательное комбинационное рассеяние, КР); 530 нм (чисто вращательное КР). Основное внимание уделяется погрешностям восстановления параметров двухкомпонентной (молекулы + аэрозоль) и трехкомпонентной (молекулы + аэрозоль + облако) среды по данным зондирования в сентябре 2021 года.

The paper presents the results of lidar observations of the atmosphere over the water area of Lake Baikal. Integrated shipboard research using the research vessel «Academician V.A. Koptyug», are held annually, using the LOSA-A2 lidar, as well as local means (gas analyzers). Additionally, satellite data and information about the meteorological parameters of the atmosphere during the experiments are involved. The route of the ship goes all over the lake. An analysis is being carried out to identify the main sources of air pollution in the Baikal region.

In this paper we have considered the features of estimating the extinction and backscattering coefficients of light, using laser sensing data at the wavelengths: 532 nm (elastic scattering, ES); 607 nm (vibrational-rotational Raman scattering, RS); 530 nm (pure-rotational RS). The main attention is paid to the errors in reconstructing the parameters of a two-component (molecules + aerosol) and three-component medium (molecules + aerosol + cloud) according to the atmospheric observations in September 2021.

Small-sized mobile lidars mainly use single-frequency sounding with registration of elastic backscattered radiation on aerosols. Mie-Raman lidars are used to correctly reconstruct the optical characteristics of an aerosol. The method most widely used in such lidar measurements for evaluating optical properties is the method of recording vibrational Raman scattering on nitrogen molecules. The disadvantages of this method are the low backscattering cross section and the significant frequency shift of the Raman vibrational component. These problems are solved by using purely rotational Raman scattering, which is characterized by a higher backscattering cross section, and a much smaller frequency shift, which practically eliminates the dependence on the Angstrom exponent. The paper presents the practical implementation of pure-rotational Raman measurements in the mobile lidar "LOSA-A2".