Radio Sounding Research Articles

Comparison of temperature, pressure and specific humidity derived from Sentinel-6 with ERA5 and radiosonde

The temperature, pressure and specific humidity data of Sentinel-6 (S6) products are compared with the ECMWF Reanalysis v5 (ERA5) and radio sounding in 2022. The overall STD of temperature, pressure and specific humidity for S6-ERA5 and S6-Radiosonde are 0.74 ℃, 0.45 hPa, 0.3 g/kg, 1.33 ℃, 0.51 hPa, 0.34 g/kg respectively. The study found that the consistency of these three atmospheric parameters between S6 and ERA5 is better than that between S6 and radiosonde. In the aspect of temporal characteristics, the specific humidity STD of S6-ERA5 decrease successively in summer, autumn, spring and winter. In the aspect of spatial characteristics, S6 has better retrieval ability of temperature values in the troposphere, but the maximum negative bias value of temperature between S6 and ERA5 is −1.57 ℃ at 41.7 km. The pressure bias values of S6 and ERA5 fluctuate greatly below the troposphere. In addition, the STD values of S6-ERA5 and S6-Radiosonde specific humidity data both show the decreasing characteristics in sequence from low to high latitudes.

Air mass transport to the tropical western Pacific troposphere inferred from ozone and relative humidity balloon observations above Palau

Abstract. The transport history of tropospheric air masses above the tropical western Pacific (TWP) is reflected by the local ozone and relative humidity (RH) characteristics. In boreal winter, the TWP is the main global entry point for air masses into the stratosphere and therefore a key region of atmospheric chemistry and dynamics. Our study aims to identify air masses with different pathways to the TWP using ozone and radio soundings from Palau from 2016–2019. Supported by backward trajectory calculations, we found five different types of air masses. We further defined locally controlled ozone and RH background profiles based on monthly statistics and analyzed corresponding anomalies in the 5–10 km altitude range. Our results show a bimodality in RH anomalies. Humid and ozone-poor background air masses are of local or Pacific convective origin and occur year-round, but they dominate from August until October. Anomalously dry and ozone-rich air masses indicate a non-local origin in tropical Asia and are transported to the TWP via an anticyclonic route, mostly from February to April. The geographic location of origin suggests anthropogenic pollution or biomass burning as a cause for ozone production. We propose large-scale descent within the tropical troposphere and radiative cooling in connection with the Hadley circulation as being responsible for the dehydration during transport. The trajectory analysis revealed no indication of a stratospheric influence. Our study thus presents a valuable contribution to the discussion about anomalous layers of dry ozone-rich air observed in ozone-poor background profiles in the TWP.

Response of the lower and upper ionosphere after the eruption of Shiveluch volcano on april 10, 2023

The disturbances in the lower ionosphere and in the region of the maximum of the ionospheric F2 layer during the Shiveluch volcanic eruption in April 2023 are analyzed based on data from ground-based magnetometers and GPS radio sounding of the ionosphere. The magnetic stations were located at distances of 455 km (Paratunka) and 752 km (Magadan) from the volcano. The variations in the magnetic field and total electron content of the ionosphere were studied as characteristics of the ionospheric response to this event. An analysis of the measurements showed that the impact on the ionosphere is carried out by seismic Rayleigh waves and atmospheric acoustic-gravity waves generated by volcanic explosions. The energy of several explosions was estimated from the amplitude of the ionospheric signal in the total electron content.

Spectral analysis of IAR oscillations to determine the value and variability of the peak electron density NmF2

This methodical paper explores the possibility of estimating the peak electron density of the F2-region of the ionosphere (NmF2) under different conditions, using data on the frequency of spectral bands (harmonics) of the ionospheric Alfvén resonator (IAR) oscillation. We describe a simple technique for tracking the frequency of spectral bands during the day by measuring their position on the plot of the IAR daily dynamic spectrum. Through calculations within the framework of the global ionospheric model IRI-2016, we verify the correctness of the comparison of the frequencies of resonant bands, measured at one point, with data from radio sounding, performed at other points remote from IAR frequency measurement sites at a distance. We propose an algorithm for comparing NmF2, measured by a radiosonde, with frequencies of spectral lines by precalculating the evaluation factor. It is formed on the basis of a nonlinear combination of the frequencies of the three observed harmonics. Then the time series of this factor is compared with the results of radio sounding, and correlation and regression coefficients, as well as estimation errors are calculated. Using the material on rare cases of round-the-clock observation of IAR oscillations in the winter months of 2011–2012, we trace the dependence of the average error in determining the peak electron density on local time. We present the data on the most favorable local time intervals for determining NmF2 from IAR harmonic frequencies depending on season. Some additional factors are discussed which affect the accuracy of estimates and determine the frequency range of IAR oscillations.

Спектральный анализ излучения ИАР для определения величины и изменчивости максимума электронной концентрации NmF2

This methodical paper explores the possibility of estimating the peak electron density of the F2-region of the ionosphere (NmF2) under different conditions, using data on the frequency of spectral bands (harmonics) of the ionospheric Alfvén resonator (IAR) oscillation. We describe a simple technique for tracking the frequency of spectral bands during the day by measuring their position on the plot of the IAR daily dynamic spectrum. Through calculations within the framework of the global ionospheric model IRI-2016, we verify the correctness of the comparison of the frequencies of resonant bands, measured at one point, with data from radio sounding, performed at other points remote from IAR frequency measurement sites at a distance. We propose an algorithm for comparing NmF2, measured by a radiosonde, with frequencies of spectral lines by precalculating the evaluation factor. It is formed on the basis of a nonlinear combination of the frequencies of the three observed harmonics. Then the time series of this factor is compared with the results of radio sounding, and correlation and regression coefficients, as well as estimation errors are calculated. Using the material on rare cases of round-the-clock observation of IAR oscillations in the winter months of 2011–2012, we trace the dependence of the average error in determining the peak electron density on local time. We present the data on the most favorable local time intervals for determining NmF2 from IAR harmonic frequencies depending on season. Some additional factors are discussed which affect the accuracy of estimates and determine the frequency range of IAR oscillations.

Large-Scale Disturbances of the Solar Wind According to Spacecraft Radio Transmission Data from the Mars Express and Local Measurements on the Wind Spacecraft

The results of experiments on radio sounding of near the Sun plasma by the signals of the MarsExpress Mars satellite are presented. In the region of heliocentric distances of the proximate point of the lineof sight of 8–13 solar radii, frequency fluctuations of transmission radio signals were measured. During theexperiments sharp increases in the variance of frequency fluctuations were recorded on both the eastern andwestern limbs. In measurements near the Earth’s orbit on the Wind spacecraft in adjacent periods with a delayof 5–17 days, increases in the proton concentration and magnetic field strength were recorded at 7–15 times thebackground values. A comparison between the data related to the inner and near-Earth solar wind indicates thatthe observed disturbances are associated with the same region of the solar corona rotating with the Sun

Comparison of Radiosonde Measurements of Meteorological Variables with Drone, Satellite Products, and WRF Simulations in the Tropical Andes: The Case of Quito, Ecuador

Radiosondes are the most widely used method for studies of vertical atmospheric behavior, but the high costs associated, and the logistic limitations have forced researchers to look for alternative methods for atmospheric profiling, such as lidar and satellite measurements, or modeling. However, the assessment of the accuracy of alternative methods is recommended, especially in complex terrain, such as the tropical Andes. In this research, the atmospheric profiling of satellite data from AIRS and MODIS products, simulations of the Weather Research and Forecasting model, WRF, and drone measurements are evaluated for a campaign of 10 radio soundings, between August 2021 and January 2022. Additionally, the capability to capture the planetary boundary layer height, hPBL, is studied. The measurements were conducted at Izobamba station near Quito, Ecuador. Temperature, T, Dew Point Temperature, TD, Mixing Ratio, Q, and Potential Temperature, PT, were evaluated from 0 to 300 m above ground level (magl.) for satellite, WRF, and drone data, and from 0 km to 15 km for satellite and WRF data. Additionally, the capability to capture the planetary boundary layer height, HPBL, was assessed. The results show that drone profiles best represented the magnitude of the analyzed variables showing mean RMSE of 0.79 for T, but the noise of the measurements caused a low correlation with radio sounding profiles, which was partially corrected with a quadratic fit on the profile. The WRF results achieved a positive representation in terms of correlation, but error metrics show that there are remarkable differences in magnitude in the first 300 magl., up to the tropopause height, which surpasses satellite representations for all variables. The MODIS profiles do not generally perform well due to their low vertical resolution and limitations with cloud coverage. However, AIRS data, despite its low resolution, show a better representation of vertical profiles than MODIS, for T and TD, surpassing WRF simulations in some dates. For the HPBL, the WRF results show that physical and atmospheric conditions limit its determination, and the methods and conditioning factors should be further analyzed.

Sea surface short-period roughness unsteadiness

The effect of spatial inhomogeneity of sea waves on the accuracy of determining the level of the sea surface is studied. Based on the data of direct wave measurements, the variability of statistical characteristics of sea waves on scales smaller than the size of the area illuminated by the radar was analyzed. The case is considered when radio sounding is carried out at low angles of incidence by radar located on a spacecraft. It is shown that the displacement of the distribution median of surface elevations, which determines the skewness bias, is alternating. The absolute value of the median shift reaches two percent of the significant wave height. In most cases, the signs of skewness bias and electromagnetic bias coincide.

Co-rotating Solar Wind Disturbances in Radio Sounding Data and Local Measurements

In this paper, we present the results of two series of experiments on radio sounding of near-solarplasma by the signals of the Mars Express and Venus Express spacecraft in 2006 and Mars Express in 2008.The radio sounding data are compared with measurements of the proton concentration near the Earth’s orbiton the Wind satellite. This analysis shows that the general nature of the temporal dynamics of disturbancesobserved in two series of measurements is qualitatively similar. The sequence of amplifications of fluctuationsin the frequency and density of protons indicates that the observed disturbances are associated with co-rotatingregions of interaction of solar wind flows of various velocities

Electromagnetic pinned solitons for space debris detection

Electromagnetic “pinned” solitons in the form of stationary nonlinear waves are studied within the framework of an inertial magneto-hydrodynamic model. These structures, that can arise when a charged source moves in a magnetized plasma, have a velocity that is equal to the source velocity and, hence, appear as “pinned” structures that envelope the source. We investigate the excitation of such solitons in the Low Earth Orbit region due to the passage of charged orbital debris objects. The spatial size of these electromagnetic solitons, typically of the order of a few ion skin depths, can be very large in this region. Such solitons can be detected using a variety of ground- or orbit-based radio sounding techniques and may provide a convenient additional means of tracking small sized orbital debris objects that are difficult to spot optically.

Characterization of Ionospheric Disturbances Following Multiple Typhoons Using GPS‐Derived TEC

AbstractTyphoon is one of the major hazards in ocean coastal areas, but traditional techniques are inadequate to monitor typhoons due to limited or high‐cost observations, like radio sounding and meteorological radar. Previous studies have found that typhoons can cause ionospheric disturbances, but the relationship and characteristics are still unclear. In this paper, about 400 stations observations of the Global Positioning System (GPS) network in Taiwan are used to extract ionospheric disturbances during multiple typhoons. The detailed characteristics of the ionospheric disturbances are investigated using a fourth‐order Butterworth filter following the 2016 Nepartak, 2019 Lekima, 2019 Mitag, and 2020 Hagupit typhoons. The results show that significant ionospheric disturbances were observed during the typhoons, and the larger disturbances are mostly located 400–1200 km far from the typhoon eye. The estimated horizontal propagation velocity of the ionospheric disturbances is about 127–194 m/s. The locations of the ionospheric disturbances between the typhoon eye and the landfall site are related to the typhoon path. The azimuth distribution of the ionospheric disturbance around the typhoon eye is affected by the GPS elevation angles. At 500–700 km from the typhoon eye, the mean ionospheric disturbances are 0.17 TECU (TEC Unit) and 0.15 TECU for super typhoon Nepartak and Lekima, and 0.13 TECU and 0.18 TECU for typhoon Mitag and Hagupit. The higher the intensity of the typhoon is, the greater the magnitude of the ionospheric disturbance is.

Application of climatological approach to determine the temperature of radiation fogs formation

The effectiveness of a radiation fog forecast is determined by the accuracy of a forecast for two values – temperature of fog formation and minimum air temperature. The accuracy of the first measurement significantly depends on a degree of adaptability of a forecast method to specific factors affecting the formation of fogs – orthography, local circulations, seasons, time of day, temperature-humidity stratification in the boundary layer of the atmosphere, etc. Taking into account each of them in a specific point will dictate its characteristics, whereas use of non-adapted fog forecasting methods will reduce their effectiveness.
 The article suggests an approach that makes it possible to carry out a comparative analysis of the prognostic value of the fog formation temperature and its average value pertaining to a specific point, season and time of day.
 In order to implement the studied approach the research considered a daily-annual repeatability of fogs at Kyiv station over 2012-2020. Based on this an average temperature of fog formation for each combination of month and time of day was determined according to actual observation data and, for the purpose of comparison, according to the Sanders method that uses data from radio sounding of the atmosphere as its baseline. The results of the analysis of the structure of the fog repeatability distribution allowed approximation of the daily-annual distribution of fog formation temperature via polynomial functions and a harmonic two-dimensional oscillator. Based on the selected efficiency criterion it was determined, via sequential selection, that the polynomial approximation of the data indicating the actual temperature of fog formation during the year is the most effective method. Obtaining an analytical form of the probability distribution function of daily and annual values of the fog formation temperature allows us to plot graphs of its daily variability for any month of the year. Such result makes it possible to control emissions of forecast values of fog formation temperature for a specific point, season and time of day, which will increase the effectiveness of the existing ways of making the forecasts in question.

Physical effects of geocosmic storms. Part 3

A review of the results of observing the effects of the most interesting ionospheric and magnetic storms that took place in 2018–2019 is presented. Ionospheric and magnetic storms are considered as components of geocosmic storms. In accordance with the systemic paradigm of L.F. Chernogor, a geocosmic storm is a complex of processes caused by a solar storm, reduced to synergistically interacting storms in a magnetic field (magnetic storm), ionosphere (ionospheric storm), atmosphere (atmospheric storm) and electric field atmospheric-ionospheric-magnetospheric origin (electric storm). Using the analysis of specific magnetic and ionospheric storms as an example, it is shown that, in addition to general patterns, each storm has its own individual characteristics. The expediency of a comprehensive study of the manifestations of each new geocosmic storm has been confirmed. A wide variety of ionospheric and magnetic storms have been confirmed. A weak magnetic storm is not necessarily accompanied by a weak ionospheric storm, while a strong one is accompanied by a strong one. An ionospheric storm can be single-phase (positive or negative) or multi-phase, when the phases alternate. Storms can last from several hours to many days. Storms are accompanied by both aperiodic and quasi-periodic variations. The latter are caused by atmospheric gravity waves (periods 10–180 min) and infrasound (period less than 5 min). Of all the components of a geocosmic storm, except for academic ones, ionospheric storms are of the greatest practical interest. It is these storms that limit the potential characteristics of radio systems for various purposes (telecommunications, radio navigation, radar, remote radio sounding, radio astronomy). It is shown that ionospheric storms are accompanied by the appearance of multipath, broadening of the Doppler spectra (and even their collapse), significant aperiodic and quasi-periodic variations in the Doppler frequency shift, the amplitude of radio signals, and the trajectories of radio waves in the decameter range. In particular, the height of reflection of radio waves changed during ionospheric storms by 50–180 km. The electron concentration during moderate negative ionospheric storms decreased up to 2 times, and during moderate positive ionospheric storms it increased up to 3 times. Under the action of atmospheric gravity waves, the relative amplitude of quasi-periodic variations in the electron concentration reached 50%, and due to low-frequency infrasound, it did not exceed 0.7%.

Mega-Eruption of the Hunga Volcano on January 15, 2022: Detection of Ionospheric Perturbations by VLF and GNSS Radio Sounding

Mega-Eruption of the Hunga Volcano on January 15, 2022: Detection of Ionospheric Perturbations by VLF and GNSS Radio Sounding

Co-rotating Solar Wind Disturbances in Radio Sounding Data and Local Measurements

Co-rotating Solar Wind Disturbances in Radio Sounding Data and Local Measurements

Toward instrument combination for boundary layer classification

AbstractTo handle the complexity of the atmospheric boundary layer (ABL) and make accurate feature detection (top height, low‐level jets, inversions, etc.), a prior necessary step is to identify the type of boundary layer. This study proposes a new method to identify the boundary layer type through unsupervised classification and the synergistic use of ground‐based remote sensing. Unsupervised classification is used to lighten the human supervision. The new classification was applied to a 1‐day case study collected during wintertime in the Arve River valley near Chamonix–Mont‐Blanc during the Passy‐2015 field experiment. The ABL classification obtained from microwave radiometer and ceilometer observations (ground‐based remote sensors [GBReS]) combination is compared with high‐frequency radiosoundings (RS) data and the French convective scale AROME model outputs. Classifications from RS and GBReS broadly agree, demonstrating the good behavior of the method, AROME leading to different results at night. The difference of AROME is likely due to the different nature of the data (model fields are smoother and include forecasting errors). The results show the ability of unsupervised classification to segment relevant objects in the boundary layer and the benefit to use a combination of GBReS.

Applicability Assessment of Coherent Doppler Wind LiDAR for Monitoring during Dusty Weather at the Northern Edge of the Tibetan Plateau

Wind profile light detection and ranging (LiDAR) is an important tool for observing features within the atmospheric boundary layer. Observations of the wind field and boundary layer height from coherent Doppler wind LiDARs (CDWLs) under sandy and dusty weather conditions were evaluated using observations from two CDWLs and one GTS radio sounding located at the northern edge of the Tibetan plateau from 1 May to 30 August 2021. The results showed that CDWL has good applicability in reproducing wind fields in dust, precipitation, and in clear-sky conditions, and that it is superior to the v wind field for real measurements of the u wind fields. In terms of the planetary boundary layer height (PBLH), the validity of the inversion of PBLH in dusty weather was higher than that under clear-sky conditions. It was found that the PBLH retrieved by the CDWL at 20:00 (BJT) was better than that at 08:00 (BJT). The diurnal variation amplitude of the PBLH before the occurrence of a sandstorm was larger than the diurnal variation amplitude of the PBLH occurring during a sandstorm.

Long-term measurements for investigating the vertical thermodynamics of an urban boundary layer with high-rise buildings

Long-term observations investigating the urban boundary layer including high-rising buildings remain inadequate. In this study, we installed two meteorological stations and utilized three other stations at five different heights in the city of Taipei, Taiwan to construct a long-term virtual potential temperature profile to investigate the thermodynamics of the urban boundary layer. Measurements using radio sounding and LIDAR validated the feasibility of this approach. Measurements from sites which are close to each other in distance but at different heights were compared to deduce historical virtual potential temperature profiles. According to changes in annual measurements, the temperature inversion layer can decrease to approximately 350 m depending on the time of year, while the warm zone near the surface during the daytime becomes volatile, and can grow up to heights more than 200 m. Importantly, our study shows that the structure of the convective urban boundary layer in Taipei is markedly different compared to previous studies, with our simulations versus a Weather Research and Forecasting model showing differences both in the height of the mixing layer and the roughness sublayer of the urban boundary layer. Improvements in heat transfer in the urban boundary layer scheme are necessary for the accuracy of current climate and weather models.

Estimation of the Tropospheric Moisture Content Derived from GPS Observations, Radio Sounding Data, and Measurements with a Water Vapor Radiometer

Estimation of the Tropospheric Moisture Content Derived from GPS Observations, Radio Sounding Data, and Measurements with a Water Vapor Radiometer

Long-term trend of surface relative humidity in Hungary

The long-term trends of relative humidity and its relationship with the long-term change of temperature are some of the unsolved problems of climate research. In this paper, the results of the analysis of long-term changes (1961–2020) in relative humidity and temperature in Hungary are presented. Homogenized station data series were used to perform the analyses. While warming was significant in each season, a significant reduction of relative humidity was observed only in spring and summer. The seasonal variability in the dependence of the change of relative humidity on the change of temperature indicates that the change of temperature directly impacts the change of relative humidity in summer, and the enhancement of evaporation due to the increase of temperature may mitigate the impact of warming in other seasons. Homogenized datasets were used to study the daily variation of the long-term trend of relative humidity. Significant reduction was found at noon in each season, except for autumn. However, the reduction was more scattered during the night, depending on the season and/or the geographical location of the station. The relationship between the surface data and data observed by radio sounding (00 UTC and 12 UTC in time period of 2007–2018) was studied to predict the long-term trends of relative humidity in the lower, 100-m deep layer of planetary boundary layer from the trend of surface relative humidity. The results suggest that this prediction can be reasonable only if daytime trends are considered.