rus
Issue #4/2023
G. I. Dolgikh, M. A. Bovsun; S. G. Dolgikh, V. A. Chupin, A. V. Yatsuk
Hardware and Software Package for the Study of Small-Scale Variations of Greenhouse Gases
Hardware and Software Package for the Study of Small-Scale Variations of Greenhouse Gases
DOI: 10.22184/1993-7296.FRos.2023.17.4.294.306
To study the nature of greenhouse gas variations, a hardware and software complex has been created, consisting of the 52.5‑meter laser strainmeter, the 17.5‑meter laser strainmeter, the laser nanobarograph and the mobile laboratory Research Vessel “Professor Gagarinsky”, consisting of an atmochemical measuring complex (Picarro gas analyzer), the complex of meteorological instruments on the upper deck of the bridge, the vessel’s gas analysis laboratory and the flow-through system. When processing experimental data on variations of deformations of the upper layer of the Earth’s crust and variations of atmospheric pressure at Shultz Cape, and in the analysis of variations of methane, carbon dioxide and water vapor in the near-water atmosphere on the shelf of the Sea of Japan at a distance of about 2 km from Shultz Cape, general patterns were established in the behavior of the studied parameters of the upper layer of the Earth’s crust and the near-water layer of the atmosphere in the infragravity range. The general powerful oscillations with periods from 7 min 59.1 s to 7 min 45.5 s, 28 min 28.8 s, from 30 min 07.6 s to 31 min 59.1 are identified, the primary source of which can be associated with both atmospheric processes and the main (radial) tone of the Earth’s own vibrations 0S0.
To study the nature of greenhouse gas variations, a hardware and software complex has been created, consisting of the 52.5‑meter laser strainmeter, the 17.5‑meter laser strainmeter, the laser nanobarograph and the mobile laboratory Research Vessel “Professor Gagarinsky”, consisting of an atmochemical measuring complex (Picarro gas analyzer), the complex of meteorological instruments on the upper deck of the bridge, the vessel’s gas analysis laboratory and the flow-through system. When processing experimental data on variations of deformations of the upper layer of the Earth’s crust and variations of atmospheric pressure at Shultz Cape, and in the analysis of variations of methane, carbon dioxide and water vapor in the near-water atmosphere on the shelf of the Sea of Japan at a distance of about 2 km from Shultz Cape, general patterns were established in the behavior of the studied parameters of the upper layer of the Earth’s crust and the near-water layer of the atmosphere in the infragravity range. The general powerful oscillations with periods from 7 min 59.1 s to 7 min 45.5 s, 28 min 28.8 s, from 30 min 07.6 s to 31 min 59.1 are identified, the primary source of which can be associated with both atmospheric processes and the main (radial) tone of the Earth’s own vibrations 0S0.
Теги: atmospheric fluctuations atmospheric pressure carbon dioxide deformation of the earth’s crust hardware and software complex methane water vapor аппаратно-программный комплекс атмосферное давление деформация земной коры колебания атмосферы метан пары воды углекислый газ
A Hardware and Software Package for the Study of Small-Scale Variations of Greenhouse Gases
G. I. Dolgikh, M. A. Bovsun; S. G. Dolgikh,
V. A. Chupin, A. V. Yatsuk
V. I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
To study the nature of greenhouse gas variations, a hardware and software complex has been created, consisting of the 52.5‑meter laser strainmeter, the 17.5‑meter laser strainmeter, the laser nanobarograph and the mobile laboratory Research Vessel “Professor Gagarinsky”, consisting of an atmochemical measuring complex (Picarro gas analyzer), the complex of meteorological instruments on the upper deck of the bridge, the vessel’s gas analysis laboratory and the flow-through system. When processing experimental data on variations of deformations of the upper layer of the Earth’s crust and variations of atmospheric pressure at Shultz Cape, and in the analysis of variations of methane, carbon dioxide and water vapor in the near-water atmosphere on the shelf of the Sea of Japan at a distance of about 2 km from Shultz Cape, general patterns were established in the behavior of the studied parameters of the upper layer of the Earth’s crust and the near-water layer of the atmosphere in the infragravity range. The general powerful oscillations with periods from 7 min 59.1 s to 7 min 45.5 s, 28 min 28.8 s, from 30 min 07.6 s to 31 min 59.1 are identified, the primary source of which can be associated with both atmospheric processes and the main (radial) tone of the Earth’s own vibrations 0S0.
Keywords: hardware and software complex, deformation of the Earth’s crust, atmospheric pressure, methane, carbon dioxide, water vapor, atmospheric fluctuations
The article received: March 30, 2023
The article accepted: May 18, 2023
INTRODUCTION
Recently, especially in the last twenty years, there have been a lot of discussions in public and in scientific circles of the problem of global climate change associated with an increase in temperature, which, in turn, leads to the degradation of permafrost, an increase in the share of greenhouse gases in the Atmosphere, which include methane and carbon dioxide. According to the work [1], it is assumed that about 40% of methane enters the atmosphere from natural sources (swamps, termites, etc.) and 60% comes from anthropogenic sources (agriculture, energy and fossil fuel extraction, landfills, etc.).
In this article, we will not discuss the problems of global climate change and related processes, but will pay attention only to the problem of studying small-scale variations in the concentration of methane, carbon dioxide and water vapor in the near-water atmosphere and finding out the nature of these variations. To study the nature of these variations, it is necessary to create a complex consisting of installations measuring variations in methane, carbon dioxide and water vapor, as well as installations measuring variations in crustal deformations, atmospheric pressure fluctuations, and of weather stations. Researches aimed at studying the nature of fluctuations in variations of the above parameters that can shed light on the dynamics of more global processes affecting the concentration of greenhouse gases in the Atmosphere. Of course, in order to perform a closed cycle of greenhouse gas release/absorption, it is necessary to involve chemical, biological and geodynamic processes. But without taking into account the solar component, these studies are not of decisive importance, especially with sharp temperature fluctuations during cold and warm observation periods. Under certain conditions, even without taking into account chemical, biological and geodynamic components, the reverse process can be observed – instead of global warming, global cooling will occur. But we are not interested in these processes at the moment. We are interested in processes of much smaller time scales and instrument complexes capable of studying the influence of these small-scale processes on the dynamics of greenhouse gases.
HARDWARE AND SOFTWARE COMPLEX
The hardware and software complex consists of laser interference installations for measuring the deformation of the Earth’s crust and variations in atmospheric pressure, located on the Shultz Cape, as well as meteorological equipment and gas analysis equipment located on the Research Vessel “Professor Gagarinsky”. During the experiment, the Research Vessel “Professor Gagarinsky” was anchored on the shelf of the Sea of Japan at a distance of 1.8 km from the location of the laser strainmeter, see Fig. 1.
The complex of meteorological equipment installed on the vessel consists of: Vaisala Weather Transmitter WXT520 meteorological complex (temperature, humidity, pressure, wind speed and direction, precipitation level), Kipp&Zonen CNR4 Net Radiometer (total, short-wave, long-wave, reflected and effective radiation, albedo, etc. parameters), photosynthetic radiation sensor LICOR LI190SB PAR Quantum Sensor (measurement of photosynthetic radiation (PAR)), CR1000 datalogger, Campbell Scientific (switching of all meteorological equipment and recording in continuous mode with 1 min averaging and saving to a separate computer).
Gas analysis equipment consists of: Picarro G2311‑f gas analyzer for high-precision continuous measurements of carbon dioxide, methane, water vapor in the near-water layer of the atmosphere, chromatographic gas complex “CRYSTALLUX 4000M” for discrete measurements of methane, hydrocarbon gases, carbon dioxide, nitrogen, oxygen in the atmosphere and the sea water column.
Atmochemical measurements were carried out using a Picarro G2311‑f laser analyzer (Picarro, USA) based on the WS-CRDS (Wave Length Scanned Ring Down Spectroscopy) system – light absorption spectroscopy in multithreaded non-axial cuvettes when scanning by wavelengths) [1–2]. The measurement speed is 10 Hz. The measurement range for CO2 is 300–500 ppm, and for CH4 1–3 ppm, respectively [2–3]. The analyzer is able to automatically correct the effect of water on measurements and assess the effect of spectral interference. Calibration of the device was carried out annually during 2018–2022, as well as immediately before and after cruises using certified gas standards for CO2 in the range of 360–500 ppm and CH4 1–3 ppm.
The gas analyzer was placed in the upper deck laboratory, equipped with a vacuum pump for continuous pumping of the outboard air and equipped with air intake devices of its own design (Fig. 2). The air intake chamber of the analyzer was located on an outrigger in the front of the vessel at an altitude of 10 m above sea level.
As a result of the measurements, an array of continuous data with a recording frequency of 10 Hz for 42 days of the expedition was obtained. All primary data was filtered out taking into account the influence of the ship’s exhaust gases. The joint analysis of CO2 concentrations, the ship’s course and wind direction (true wind direction) makes it possible to effectively carry out such data culling. Further, the entire data array was averaged over 1 and 5 min time intervals and combined with meteorological parameters.
A laser nanobarograph and laser strainmeters with measuring arm lengths of 52.5 and 17.5 m are located on Shultz Cape (see Fig. 3). The laser nanobarograph is based on an equal-arm Michelson interferometer using a frequency-stabilized helium-neon laser from the company Melles Griot, which provides frequency stability in the ninth sign, a block of aneroid boxes with mirror spraying, a digital registration system and the unit of the transmission of the obtained experimental data to the experimental data base. It has the following technical characteristics: the operating frequency range from 0 (conditionally) to 10 kHz, the accuracy of measuring atmospheric pressure variations is 50 µPa [4].
Two laser strainmeters of unequal-arm type are mounted on Shultz Cape at a depth of 3–5 m from the earth’s surface. One laser strainmeter with a measuring arm length of 52.5 m is located at an angle of 18° relative to the north-south line, and another laser strainmeter with a measuring arm length of 17.5 m is located at an angle of 92° relative to the laser strainmeter with a measuring arm length of 52.5 m. All laser strainmeters are based on the Michelson interferometer of unequal-arm type with the use of frequency-stabilized helium-neon lasers with a frequency stability of 9–12 signs as a light source. This makes it possible to achieve the following technical characteristics: the accuracy of measuring the displacements of the Earth’s crust is 10 pm, the operating frequency range is from 0 (conditionally) to 1000 Hz [5].
Not far from the laboratory room (pos. 3 in fig. 3) there is a weather station on the mast that measures various meteorological parameters.
All data from Shultz Сape measuring systems are recorded in real time on a writing computer, where, after preliminary processing (filtering and decimation), they are entered into a previously created experimental database. All data is “tied” to the exact time clock using GPS TRIMBLE 5700, which are designed to ensure the accuracy of time counts at a level not worse than 1 microsecond.
PROCESSING AND ANALYSIS OF THE EXPERIMENTAL DATA OBTAINED
Experimental studies took place in various weather conditions, which led to some distortion of the experimental data obtained, therefore, a limited series of data with a duration from 13 hours 50 minutes on November 22 to 3 hours 37 minutes on November 29 was selected for processing and analysis. Variations in the concentration of methane, carbon dioxide and water vapor were measured on the vessel, and on Schultz Cape – deformations of the Earth’s crust using laser strainmeters and variations in atmospheric pressure using a laser meter of variations in hydrosphere pressure. Fig. 4 shows almost synchronous experimental data on variations in the concentration of methane, carbon dioxide, water vapor, micro-deformations of the Earth’s crust, measured by the 17.5‑meter laser strainmeter, and variations in atmospheric pressure, measured by the laser nanobarograph on Shultz Cape.
Upon visual inspection of these graphs, it can be noted that there are many abnormal emissions in the records of variations in the concentration of carbon dioxide, which may be associated with the influence of vital activity on the vessel, the variations in water vapor and deformations of the upper layer of the Earth’s crust poorly correlate with variations in other parameters. Almost synchronous anomalous behavior is observed in the behavior of atmospheric pressure variations and methane concentration variations. A sharp change in atmospheric pressure correlates with a sharp peak of methane. With a sharp change in atmospheric pressure around 6700 Pa, the magnitude of the methane concentration pulse was 0.19 ppm, which is almost 4 times greater than the background value. It can also be noted that these sharp methane peak and a jump in atmospheric pressure correlate with a sharp decrease in humidity of about 25%.
Next, we will analyze the changes in the parameters placed in Fig. 4 in the infragravity frequency range, i. e. in the range of periods from 1 to 50 minutes. Let’s analyze the behavior of fluctuations in different ranges of periods. In the range of periods from 1 to 10 minutes in the initial observation period (November 22), during spectral processing of laser strainmeters and laser nanobarograph, powerful spectral components are observed at periods of 7 min 59.1 s, which sometimes decreases to a period of 7 min 52.6 s and 7 min 45.5 s. As a typical example Fig. 5 shows the spectra obtained by processing synchronous recordings of the laser strainmeter with a measuring arm length of 52.5 m, the laser nanobarograph and the laser strainmeter with a measuring arm length of 17.5 m. On the spectrum obtained by processing the recording of the 52.5‑meter laser strainmeter, the first peak corresponds to a period of 7 min 59.1 s, although the peak with a period of 6 min 55.1 s is the maximum. On the spectrum obtained by processing the recording of the laser nanobarograph, the maximum peak with a period of 7 min 59.1 s is allocated. On the spectrum obtained by processing the recording of the 17.5‑meter laser strainmeter, there is a maximum peak with a period of 9 min 28.9 s, and the second largest peak refers to a period of 7 min 59.1 s. When comparing the obtained spectra shown in Fig. 5, it can be argued that all three instruments located on Shultz Cape registered oscillations with a period of about 7 min 59.1 s. Although, as mentioned above, the magnitude of the period of these fluctuations varies over time within certain limits, which may be due to both natural processes, for example, the phenomenon of non-isochronism, and the processing effect, when lower-frequency processes of large amplitude, and trends, could have an impact on the exact determination of the periods of these fluctuations.
Towards the end of the experiment (November 28), powerful spectral components in this period range were observed not on Shultz Cape, but in the location of the Research Vessel “Professor Gagarinsky”. Figure 6 shows the spectra obtained during the processing of synchronous sections of records on variations in concentrations of methane, carbon dioxide and water vapor, where powerful spectral components are allocated for periods of 7 min 45.5 s, 7 min 38.5 s and 7 min 38.5 s, respectively. During the same observation period in this period range, peaks at a period of 8 min 40.7 s are distinguished from the records of the laser strainmeters and the laser nanobarograph. Such a transformation of oscillation periods is incomprehensible. It turns out that fluctuations with higher frequency periods for several days were displaced by lower frequency processes from the territory of the Shultz Cape. As can be seen from graphs 6a, 6b and 6c, a powerful peak with a period of about 7 min 45.5 s and 7 min 38.5 s is distinguished on all of therm. Considering that when processing a series with a duration of 512 points and at a sampling frequency of 0.016(6) Hz in the spectrum obtained on the basis of the fast Fourier transform, harmonics with periods of 7 min 45.5 s and 7 min 38.5 s are nearby, it can be argued that this is the same peak related to one and the same natural process. Taking into account this circumstance, as well as the graphs shown in Fig. 5, it can be assumed that these fluctuations in variations of deformations of the upper layer of the Earth’s crust on the Shultz Cape, fluctuations in atmospheric pressure on the Shultz Cape, as well as fluctuations in the concentration of methane, carbon dioxide and water vapor in the sea, a few kilometers from the Shultz Cape, are caused by the same processes, which, most likely, can be attributed to atmospheric fluctuations of the infragravity range. It can be noted, however, that these fluctuations are not always observed simultaneously at installations located in the same place. Thus, Figure 7 shows the spectra obtained during the processing of synchronous recordings of the concentration of methane, carbon dioxide and water vapor. When comparing the graphs shown in Fig.7a and 7b, a powerful peak is observed with a period of 7 min 45.5 s, but there is no such peak on the graph of water vapor concentration, and the peak is observed at a period of 6 min 44.2 s. That is, not always infragravity fluctuations cause synchronously corresponding fluctuations in the measured parameters of geospheres.
Let’s consider further lower frequency ranges. In the range of periods from 10 to 20 min, it is possible to distinguish fluctuations at periods of 18 min 17.1 s in the records of the 52.5‑meter laser strainmeter, the laser nanobarograph and the carbon dioxide concentrations, 17 min 39.1 s in the records of, mainly, methane concentrations, and concentrations of carbon dioxide, water vapor and atmospheric pressure variations on the Shultz Cape sometimes, 17 min 04.0 s in the records of the laser nanobarograph and water vapor, In the range of 20–30 min periods, powerful peaks are distinguished at the maximum corresponding to the period 20 min 28.8 s. These peaks are distinguished when processing records of both laser strainmeters and the laser nanobarograph, large peaks with this period are distinguished when processing records of water vapor concentration. Nearby maxima with periods of 21min19.1s can also be noted, which are observed at separate time intervals on the spectra allocated during processing of the records of the 52.5‑meter laser strainmeter, the laser nanobarograph, the records of methane and carbon dioxide concentrations. Fluctuations with a period of 25 min 35.1 s are distinguished from the records of the laser strainmeters, the laser nanobarograph and water vapor. Fluctuations with a period of 28 min 26.7 s are distinguished from the records of the laser strainmeters, the laser nanobarograph, concentrations of methane, carbon dioxide and water vapor. In the lower frequency range, when processing records of all devices, a maximum with a “floating” period from 30 min 07.6 s to 31 min 59.1 s is distinguished, which are detected both in the spectra of concentrations of methane, carbon dioxide and water vapor, and in the spectra of records of the laser strainmeters and the laser nanobarograph. At the same time, in the spectra of concentrations of methane, carbon dioxide and water vapor, their intensity is noticeably greater, see, for example, Fig. 8. For the spectra obtained by processing data on concentrations of methane and water vapor, the peak with a period of 31 min 59.1 s has the maximum value, and in the carbon dioxide spectrum it is the second largest.
CONCLUSION
When analyzing the data obtained from variations in the deformation of the Earth’s crust and atmospheric pressure on the Shultz Cape, as well as from variations in the concentrations of methane, carbon dioxide and water vapor, the following patterns were established:
A sharp change in atmospheric pressure correlates with a sharp rise in methane levels. With a sharp change in atmospheric pressure around 6 700 Pa, the magnitude of the methane concentration pulse was 0.19 ppm, which is almost 4 times greater than the background value. It can also be noted that these sharp methane peak and a jump in atmospheric pressure correlate with a sharp decrease in humidity by about 25%.
Powerful “wandering” peaks with periods from 7 min 59.1 s to 7 min 45.5 s are observed in the spectra of recordings of the laser strainmeters and the laser nanobarograph, which peaks after a while stand out in the recordings of variations in concentrations of methane, carbon dioxide and water vapor, at the same time in the spectra of deformations of the Earth’s crust and atmospheric pressure on the Shultz Capes peaks with slightly longer periods are distinguished. It can be assumed that these fluctuations are caused by some atmospheric depression, which for several days slowly shifted from the Shultz Cape to the location of the Research Vessel “Professor Gagarinsky”, in which atmospheric inhomogeneities in space increased by size.
The origin of fluctuations in the lower frequency range (10–30 min) is difficult to explain without performing additional experiments. Nevertheless, it can be assumed that the maximum with a period of 20 min 28.8 s may be due to the spheroidal tone 0S0, which, according to [6], causes fluctuations in atmospheric pressure of the same period.
Fluctuations of large periods (from 30 min 07.6 s to 31 min 59.1 s) were previously distinguished in the records of sea level fluctuations during the passage of an atmospheric pulse over the Sea of Japan resulting from the explosion of the Hunga Tonga-Hunga Ha’apai volcano, [7]. The origin of this fluctuation was first explained by the excitation of one of the seishas of the Sea of Japan, but later it was found that these fluctuations are caused by the own fluctuations of the troposphere, i. e. Lamb waves. The change in the periods of these fluctuations is associated with a change in the size of the corresponding layers of the troposphere.
Source of financing. The work was carried out within the framework of the implementation of the most important innovative project of national importance “Unified National Monitoring System of Climatically Active Substances” in the implementation of the topic of the Pacific Oceanological Institute, Far-Eastern Division of Russian Academy of Sciences “Development of Methods for Integrated Gas-Geochemical Monitoring of the Far Eastern Seas, Generalization of Gas-Geochemical Knowledge and the Current Level of Concentrations and Sources of Greenhouse Gases in the Bottom-Ocean-Atmosphere System”, as well as with partial funding for topic no. AAAA-A20-120021990003–3 (obtaining experimental data on the Schultz Cape).
AUTHORS
Dolgikh G. I., Academician RAS, Doctor of Phys&Math Sciences Ph.-M, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Russia, dolgikh@poi.dvo.ru.
ORCID: 0000-0002-2806-3834
Bovsun M. A., V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0003-1916-3566
Dolgikh S. G., Doctor of Technical Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0001-9828-5929
Chupin V. A., Candidate of Phys&Math Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0001-5103-8138
Yatsuk A. V., Candidate of Geological-Mineralogical Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Science
G. I. Dolgikh, M. A. Bovsun; S. G. Dolgikh,
V. A. Chupin, A. V. Yatsuk
V. I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
To study the nature of greenhouse gas variations, a hardware and software complex has been created, consisting of the 52.5‑meter laser strainmeter, the 17.5‑meter laser strainmeter, the laser nanobarograph and the mobile laboratory Research Vessel “Professor Gagarinsky”, consisting of an atmochemical measuring complex (Picarro gas analyzer), the complex of meteorological instruments on the upper deck of the bridge, the vessel’s gas analysis laboratory and the flow-through system. When processing experimental data on variations of deformations of the upper layer of the Earth’s crust and variations of atmospheric pressure at Shultz Cape, and in the analysis of variations of methane, carbon dioxide and water vapor in the near-water atmosphere on the shelf of the Sea of Japan at a distance of about 2 km from Shultz Cape, general patterns were established in the behavior of the studied parameters of the upper layer of the Earth’s crust and the near-water layer of the atmosphere in the infragravity range. The general powerful oscillations with periods from 7 min 59.1 s to 7 min 45.5 s, 28 min 28.8 s, from 30 min 07.6 s to 31 min 59.1 are identified, the primary source of which can be associated with both atmospheric processes and the main (radial) tone of the Earth’s own vibrations 0S0.
Keywords: hardware and software complex, deformation of the Earth’s crust, atmospheric pressure, methane, carbon dioxide, water vapor, atmospheric fluctuations
The article received: March 30, 2023
The article accepted: May 18, 2023
INTRODUCTION
Recently, especially in the last twenty years, there have been a lot of discussions in public and in scientific circles of the problem of global climate change associated with an increase in temperature, which, in turn, leads to the degradation of permafrost, an increase in the share of greenhouse gases in the Atmosphere, which include methane and carbon dioxide. According to the work [1], it is assumed that about 40% of methane enters the atmosphere from natural sources (swamps, termites, etc.) and 60% comes from anthropogenic sources (agriculture, energy and fossil fuel extraction, landfills, etc.).
In this article, we will not discuss the problems of global climate change and related processes, but will pay attention only to the problem of studying small-scale variations in the concentration of methane, carbon dioxide and water vapor in the near-water atmosphere and finding out the nature of these variations. To study the nature of these variations, it is necessary to create a complex consisting of installations measuring variations in methane, carbon dioxide and water vapor, as well as installations measuring variations in crustal deformations, atmospheric pressure fluctuations, and of weather stations. Researches aimed at studying the nature of fluctuations in variations of the above parameters that can shed light on the dynamics of more global processes affecting the concentration of greenhouse gases in the Atmosphere. Of course, in order to perform a closed cycle of greenhouse gas release/absorption, it is necessary to involve chemical, biological and geodynamic processes. But without taking into account the solar component, these studies are not of decisive importance, especially with sharp temperature fluctuations during cold and warm observation periods. Under certain conditions, even without taking into account chemical, biological and geodynamic components, the reverse process can be observed – instead of global warming, global cooling will occur. But we are not interested in these processes at the moment. We are interested in processes of much smaller time scales and instrument complexes capable of studying the influence of these small-scale processes on the dynamics of greenhouse gases.
HARDWARE AND SOFTWARE COMPLEX
The hardware and software complex consists of laser interference installations for measuring the deformation of the Earth’s crust and variations in atmospheric pressure, located on the Shultz Cape, as well as meteorological equipment and gas analysis equipment located on the Research Vessel “Professor Gagarinsky”. During the experiment, the Research Vessel “Professor Gagarinsky” was anchored on the shelf of the Sea of Japan at a distance of 1.8 km from the location of the laser strainmeter, see Fig. 1.
The complex of meteorological equipment installed on the vessel consists of: Vaisala Weather Transmitter WXT520 meteorological complex (temperature, humidity, pressure, wind speed and direction, precipitation level), Kipp&Zonen CNR4 Net Radiometer (total, short-wave, long-wave, reflected and effective radiation, albedo, etc. parameters), photosynthetic radiation sensor LICOR LI190SB PAR Quantum Sensor (measurement of photosynthetic radiation (PAR)), CR1000 datalogger, Campbell Scientific (switching of all meteorological equipment and recording in continuous mode with 1 min averaging and saving to a separate computer).
Gas analysis equipment consists of: Picarro G2311‑f gas analyzer for high-precision continuous measurements of carbon dioxide, methane, water vapor in the near-water layer of the atmosphere, chromatographic gas complex “CRYSTALLUX 4000M” for discrete measurements of methane, hydrocarbon gases, carbon dioxide, nitrogen, oxygen in the atmosphere and the sea water column.
Atmochemical measurements were carried out using a Picarro G2311‑f laser analyzer (Picarro, USA) based on the WS-CRDS (Wave Length Scanned Ring Down Spectroscopy) system – light absorption spectroscopy in multithreaded non-axial cuvettes when scanning by wavelengths) [1–2]. The measurement speed is 10 Hz. The measurement range for CO2 is 300–500 ppm, and for CH4 1–3 ppm, respectively [2–3]. The analyzer is able to automatically correct the effect of water on measurements and assess the effect of spectral interference. Calibration of the device was carried out annually during 2018–2022, as well as immediately before and after cruises using certified gas standards for CO2 in the range of 360–500 ppm and CH4 1–3 ppm.
The gas analyzer was placed in the upper deck laboratory, equipped with a vacuum pump for continuous pumping of the outboard air and equipped with air intake devices of its own design (Fig. 2). The air intake chamber of the analyzer was located on an outrigger in the front of the vessel at an altitude of 10 m above sea level.
As a result of the measurements, an array of continuous data with a recording frequency of 10 Hz for 42 days of the expedition was obtained. All primary data was filtered out taking into account the influence of the ship’s exhaust gases. The joint analysis of CO2 concentrations, the ship’s course and wind direction (true wind direction) makes it possible to effectively carry out such data culling. Further, the entire data array was averaged over 1 and 5 min time intervals and combined with meteorological parameters.
A laser nanobarograph and laser strainmeters with measuring arm lengths of 52.5 and 17.5 m are located on Shultz Cape (see Fig. 3). The laser nanobarograph is based on an equal-arm Michelson interferometer using a frequency-stabilized helium-neon laser from the company Melles Griot, which provides frequency stability in the ninth sign, a block of aneroid boxes with mirror spraying, a digital registration system and the unit of the transmission of the obtained experimental data to the experimental data base. It has the following technical characteristics: the operating frequency range from 0 (conditionally) to 10 kHz, the accuracy of measuring atmospheric pressure variations is 50 µPa [4].
Two laser strainmeters of unequal-arm type are mounted on Shultz Cape at a depth of 3–5 m from the earth’s surface. One laser strainmeter with a measuring arm length of 52.5 m is located at an angle of 18° relative to the north-south line, and another laser strainmeter with a measuring arm length of 17.5 m is located at an angle of 92° relative to the laser strainmeter with a measuring arm length of 52.5 m. All laser strainmeters are based on the Michelson interferometer of unequal-arm type with the use of frequency-stabilized helium-neon lasers with a frequency stability of 9–12 signs as a light source. This makes it possible to achieve the following technical characteristics: the accuracy of measuring the displacements of the Earth’s crust is 10 pm, the operating frequency range is from 0 (conditionally) to 1000 Hz [5].
Not far from the laboratory room (pos. 3 in fig. 3) there is a weather station on the mast that measures various meteorological parameters.
All data from Shultz Сape measuring systems are recorded in real time on a writing computer, where, after preliminary processing (filtering and decimation), they are entered into a previously created experimental database. All data is “tied” to the exact time clock using GPS TRIMBLE 5700, which are designed to ensure the accuracy of time counts at a level not worse than 1 microsecond.
PROCESSING AND ANALYSIS OF THE EXPERIMENTAL DATA OBTAINED
Experimental studies took place in various weather conditions, which led to some distortion of the experimental data obtained, therefore, a limited series of data with a duration from 13 hours 50 minutes on November 22 to 3 hours 37 minutes on November 29 was selected for processing and analysis. Variations in the concentration of methane, carbon dioxide and water vapor were measured on the vessel, and on Schultz Cape – deformations of the Earth’s crust using laser strainmeters and variations in atmospheric pressure using a laser meter of variations in hydrosphere pressure. Fig. 4 shows almost synchronous experimental data on variations in the concentration of methane, carbon dioxide, water vapor, micro-deformations of the Earth’s crust, measured by the 17.5‑meter laser strainmeter, and variations in atmospheric pressure, measured by the laser nanobarograph on Shultz Cape.
Upon visual inspection of these graphs, it can be noted that there are many abnormal emissions in the records of variations in the concentration of carbon dioxide, which may be associated with the influence of vital activity on the vessel, the variations in water vapor and deformations of the upper layer of the Earth’s crust poorly correlate with variations in other parameters. Almost synchronous anomalous behavior is observed in the behavior of atmospheric pressure variations and methane concentration variations. A sharp change in atmospheric pressure correlates with a sharp peak of methane. With a sharp change in atmospheric pressure around 6700 Pa, the magnitude of the methane concentration pulse was 0.19 ppm, which is almost 4 times greater than the background value. It can also be noted that these sharp methane peak and a jump in atmospheric pressure correlate with a sharp decrease in humidity of about 25%.
Next, we will analyze the changes in the parameters placed in Fig. 4 in the infragravity frequency range, i. e. in the range of periods from 1 to 50 minutes. Let’s analyze the behavior of fluctuations in different ranges of periods. In the range of periods from 1 to 10 minutes in the initial observation period (November 22), during spectral processing of laser strainmeters and laser nanobarograph, powerful spectral components are observed at periods of 7 min 59.1 s, which sometimes decreases to a period of 7 min 52.6 s and 7 min 45.5 s. As a typical example Fig. 5 shows the spectra obtained by processing synchronous recordings of the laser strainmeter with a measuring arm length of 52.5 m, the laser nanobarograph and the laser strainmeter with a measuring arm length of 17.5 m. On the spectrum obtained by processing the recording of the 52.5‑meter laser strainmeter, the first peak corresponds to a period of 7 min 59.1 s, although the peak with a period of 6 min 55.1 s is the maximum. On the spectrum obtained by processing the recording of the laser nanobarograph, the maximum peak with a period of 7 min 59.1 s is allocated. On the spectrum obtained by processing the recording of the 17.5‑meter laser strainmeter, there is a maximum peak with a period of 9 min 28.9 s, and the second largest peak refers to a period of 7 min 59.1 s. When comparing the obtained spectra shown in Fig. 5, it can be argued that all three instruments located on Shultz Cape registered oscillations with a period of about 7 min 59.1 s. Although, as mentioned above, the magnitude of the period of these fluctuations varies over time within certain limits, which may be due to both natural processes, for example, the phenomenon of non-isochronism, and the processing effect, when lower-frequency processes of large amplitude, and trends, could have an impact on the exact determination of the periods of these fluctuations.
Towards the end of the experiment (November 28), powerful spectral components in this period range were observed not on Shultz Cape, but in the location of the Research Vessel “Professor Gagarinsky”. Figure 6 shows the spectra obtained during the processing of synchronous sections of records on variations in concentrations of methane, carbon dioxide and water vapor, where powerful spectral components are allocated for periods of 7 min 45.5 s, 7 min 38.5 s and 7 min 38.5 s, respectively. During the same observation period in this period range, peaks at a period of 8 min 40.7 s are distinguished from the records of the laser strainmeters and the laser nanobarograph. Such a transformation of oscillation periods is incomprehensible. It turns out that fluctuations with higher frequency periods for several days were displaced by lower frequency processes from the territory of the Shultz Cape. As can be seen from graphs 6a, 6b and 6c, a powerful peak with a period of about 7 min 45.5 s and 7 min 38.5 s is distinguished on all of therm. Considering that when processing a series with a duration of 512 points and at a sampling frequency of 0.016(6) Hz in the spectrum obtained on the basis of the fast Fourier transform, harmonics with periods of 7 min 45.5 s and 7 min 38.5 s are nearby, it can be argued that this is the same peak related to one and the same natural process. Taking into account this circumstance, as well as the graphs shown in Fig. 5, it can be assumed that these fluctuations in variations of deformations of the upper layer of the Earth’s crust on the Shultz Cape, fluctuations in atmospheric pressure on the Shultz Cape, as well as fluctuations in the concentration of methane, carbon dioxide and water vapor in the sea, a few kilometers from the Shultz Cape, are caused by the same processes, which, most likely, can be attributed to atmospheric fluctuations of the infragravity range. It can be noted, however, that these fluctuations are not always observed simultaneously at installations located in the same place. Thus, Figure 7 shows the spectra obtained during the processing of synchronous recordings of the concentration of methane, carbon dioxide and water vapor. When comparing the graphs shown in Fig.7a and 7b, a powerful peak is observed with a period of 7 min 45.5 s, but there is no such peak on the graph of water vapor concentration, and the peak is observed at a period of 6 min 44.2 s. That is, not always infragravity fluctuations cause synchronously corresponding fluctuations in the measured parameters of geospheres.
Let’s consider further lower frequency ranges. In the range of periods from 10 to 20 min, it is possible to distinguish fluctuations at periods of 18 min 17.1 s in the records of the 52.5‑meter laser strainmeter, the laser nanobarograph and the carbon dioxide concentrations, 17 min 39.1 s in the records of, mainly, methane concentrations, and concentrations of carbon dioxide, water vapor and atmospheric pressure variations on the Shultz Cape sometimes, 17 min 04.0 s in the records of the laser nanobarograph and water vapor, In the range of 20–30 min periods, powerful peaks are distinguished at the maximum corresponding to the period 20 min 28.8 s. These peaks are distinguished when processing records of both laser strainmeters and the laser nanobarograph, large peaks with this period are distinguished when processing records of water vapor concentration. Nearby maxima with periods of 21min19.1s can also be noted, which are observed at separate time intervals on the spectra allocated during processing of the records of the 52.5‑meter laser strainmeter, the laser nanobarograph, the records of methane and carbon dioxide concentrations. Fluctuations with a period of 25 min 35.1 s are distinguished from the records of the laser strainmeters, the laser nanobarograph and water vapor. Fluctuations with a period of 28 min 26.7 s are distinguished from the records of the laser strainmeters, the laser nanobarograph, concentrations of methane, carbon dioxide and water vapor. In the lower frequency range, when processing records of all devices, a maximum with a “floating” period from 30 min 07.6 s to 31 min 59.1 s is distinguished, which are detected both in the spectra of concentrations of methane, carbon dioxide and water vapor, and in the spectra of records of the laser strainmeters and the laser nanobarograph. At the same time, in the spectra of concentrations of methane, carbon dioxide and water vapor, their intensity is noticeably greater, see, for example, Fig. 8. For the spectra obtained by processing data on concentrations of methane and water vapor, the peak with a period of 31 min 59.1 s has the maximum value, and in the carbon dioxide spectrum it is the second largest.
CONCLUSION
When analyzing the data obtained from variations in the deformation of the Earth’s crust and atmospheric pressure on the Shultz Cape, as well as from variations in the concentrations of methane, carbon dioxide and water vapor, the following patterns were established:
A sharp change in atmospheric pressure correlates with a sharp rise in methane levels. With a sharp change in atmospheric pressure around 6 700 Pa, the magnitude of the methane concentration pulse was 0.19 ppm, which is almost 4 times greater than the background value. It can also be noted that these sharp methane peak and a jump in atmospheric pressure correlate with a sharp decrease in humidity by about 25%.
Powerful “wandering” peaks with periods from 7 min 59.1 s to 7 min 45.5 s are observed in the spectra of recordings of the laser strainmeters and the laser nanobarograph, which peaks after a while stand out in the recordings of variations in concentrations of methane, carbon dioxide and water vapor, at the same time in the spectra of deformations of the Earth’s crust and atmospheric pressure on the Shultz Capes peaks with slightly longer periods are distinguished. It can be assumed that these fluctuations are caused by some atmospheric depression, which for several days slowly shifted from the Shultz Cape to the location of the Research Vessel “Professor Gagarinsky”, in which atmospheric inhomogeneities in space increased by size.
The origin of fluctuations in the lower frequency range (10–30 min) is difficult to explain without performing additional experiments. Nevertheless, it can be assumed that the maximum with a period of 20 min 28.8 s may be due to the spheroidal tone 0S0, which, according to [6], causes fluctuations in atmospheric pressure of the same period.
Fluctuations of large periods (from 30 min 07.6 s to 31 min 59.1 s) were previously distinguished in the records of sea level fluctuations during the passage of an atmospheric pulse over the Sea of Japan resulting from the explosion of the Hunga Tonga-Hunga Ha’apai volcano, [7]. The origin of this fluctuation was first explained by the excitation of one of the seishas of the Sea of Japan, but later it was found that these fluctuations are caused by the own fluctuations of the troposphere, i. e. Lamb waves. The change in the periods of these fluctuations is associated with a change in the size of the corresponding layers of the troposphere.
Source of financing. The work was carried out within the framework of the implementation of the most important innovative project of national importance “Unified National Monitoring System of Climatically Active Substances” in the implementation of the topic of the Pacific Oceanological Institute, Far-Eastern Division of Russian Academy of Sciences “Development of Methods for Integrated Gas-Geochemical Monitoring of the Far Eastern Seas, Generalization of Gas-Geochemical Knowledge and the Current Level of Concentrations and Sources of Greenhouse Gases in the Bottom-Ocean-Atmosphere System”, as well as with partial funding for topic no. AAAA-A20-120021990003–3 (obtaining experimental data on the Schultz Cape).
AUTHORS
Dolgikh G. I., Academician RAS, Doctor of Phys&Math Sciences Ph.-M, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Russia, dolgikh@poi.dvo.ru.
ORCID: 0000-0002-2806-3834
Bovsun M. A., V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0003-1916-3566
Dolgikh S. G., Doctor of Technical Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0001-9828-5929
Chupin V. A., Candidate of Phys&Math Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences, Vladivostok, Россия.
ORCID: 0000-0001-5103-8138
Yatsuk A. V., Candidate of Geological-Mineralogical Sciences, V. I. Il’ichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Science
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