Journal of Atmospheric and Solar-Terrestrial Physics最新文献

{"title":"Characterization of gravity wave events detected in the low ionosphere at the Brazilian Antarctic Station","authors":"Luís Tiago Medeiros Raunheitte ,&nbsp;Emilia Correia ,&nbsp;Jean Pierre Raulin ,&nbsp;José Valentin Bageston","doi":"10.1016/j.jastp.2024.106383","DOIUrl":"10.1016/j.jastp.2024.106383","url":null,"abstract":"<div><div>Here we present the characteristics of three distinct types of Gravity Wave (GW) events as detected in the low ionosphere using very low frequencies (VLF) radio measurements performed at the EACF, Brazilian Antarctic Station Comandante Ferraz (62° 5′ 6″ S, 58° 24′ 12″ W), on King George Island. GWs in the low ionosphere produce oscillations in the electron density, which can be detected as amplitude and phase fluctuations of the VLF signals. The properties of the GW events are obtained using Morlet's Wavelet analysis, which gives the period of the waves, and their occurrence time. The period and duration of the GW events obtained using the VLF technique presented good agreement with ones previously obtained from airglow observations from a co-located all-sky imager. The VLF detection of the mesospheric front showed the same morphology seen with the imager with four crests identified, and the wave activity presented similar period range (∼4–16 min) as observed by airglow (∼6 min) with a period peak of 14 min equal to the spectral analysis of the concurrent OH temperature data. The activity associated with the band event presented similar period of ∼10 min (imager observed 13 min), same duration of 4 h as well as peak intensity just before 05:00 UT. The ripple detection showed the same period of 8 min as the airglow observations and similar duration of around 25 min. By considering two distinct VLF paths it was also possible to analyze the direction and velocity of propagation for the mesospheric front event, which gives 96.0 (±4.8) ms⁻¹ in the East direction in agreement with the velocity of ∼92 ms⁻¹ in the Northeast direction obtained from the airglow observations.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"265 ","pages":"Article 106383"},"PeriodicalIF":1.8,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential responses of total ozone content to solar activity parameters at two Saudi Arabian locations","authors":"Abdullrahman Maghrabi,&nbsp;Mayson Alghamdi","doi":"10.1016/j.jastp.2024.106379","DOIUrl":"10.1016/j.jastp.2024.106379","url":null,"abstract":"<div><div>This study examines the correlations between Total Ozone Content (TOC) at two locations in Saudi Arabia—Abha and Jeddah—and various solar activity indicators (sunspot numbers, solar radio flux) and cosmic rays, using data spanning from 1979 to 2023. The research employs correlation analyses and spectral techniques, such as Fast Fourier Transform and wavelet analysis, to explore these relationships.</div><div>The results reveal significant non-zero correlations between changes in TOC at both Saudi sites and the studied solar activity indicators and cosmic rays, with these correlations varying in strength and significance across different solar cycles and seasons.</div><div>Spectral analysis suggests the presence of several periodicities in the TOC data from both sites, including cycles of 3.9 years, 2.63 years, 1.65 years, 1.1–1.2 years, 325 days (∼0.88 years), 285–293 days (∼0.78–0.80 years), 273 days (∼0.75 years), 249-232 days (∼0.68 years), and 202-188 days (∼0.52 years). Notable shared periodicities between TOC and solar activity and cosmic rays data include ∼2.6 years, 3.8–3.9 years, 1.56 years, 325 days, 273 days, and 166 days.</div><div>The findings from both correlation and spectral analyses suggest a potential connection between variations in TOC and solar activity at the specific locations studied. This aligns with previous research indicating that increased UV radiation during periods of high solar activity enhances ozone production, particularly at lower latitudes, and that increased magnetic activity reduces the influx of cosmic rays into the heliosphere, impacting atmospheric ionization.</div></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"265 ","pages":"Article 106379"},"PeriodicalIF":1.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of aerosols on surface ozone during COVID-19 pandemic in southern India: A multi-instrumental approach from ground and satellite observations, and model simulations","authors":"Raja Obul Reddy Kalluri,&nbsp;Balakrishnaiah Gugamsetty,&nbsp;Chakradhar Rao Tandule,&nbsp;Rama Gopal Kotalo,&nbsp;Lokeswara Reddy Thotli,&nbsp;Ramakrishna Reddy Rajuru,&nbsp;Surya Nagi Reddy Palle","doi":"10.1016/j.jastp.2020.105491","DOIUrl":"10.1016/j.jastp.2020.105491","url":null,"abstract":"<div><p>The World Health Organization (WHO) declared the coronavirus disease of 2019 (COVID-19) as a pandemic due to its widespread global infection. This has resulted in lockdown under different phases in many nations, including India, around the globe. In the present study, we report the impact of aerosols on surface ozone in the context of pre-lockdown (01^st - 24th March 2020 (PLD)), lockdown phase1 (25th March to 14th April 2020 (LDP1)), and lockdown phase 2 (15th April to 03^rd May 2020 (LDP2)) on clear days at a semi-arid site, Anantapur in southern India using both in situ observations and model simulations. Collocated measurements of surface ozone (O₃), aerosol optical depth (AOD), black carbon mass concentration (BC), total columnar ozone (TCO), solar radiation (SR), and ultraviolet radiation (UV-A) data were collected using an Ozone analyzer, MICROTOPS sunphotometer, Ozonometer, Aethalometer, and net radiometer during the study period. The diurnal variations of O₃ and BC exhibited an opposite trend during three phases. The concentrations of ozone were ~10.7% higher during LDP1 (44.8 ± 5.2 ppbv) than the PLD (40.5 ± 6.0 ppbv), which mainly due to an unprecedented reduction in NOx emissions leading to a lower O₃ titration by NO. The prominent increase in the surface zone during LDP1 is reasonably consistent with the observed photolysis frequencies (j (O¹D)) through Tropospheric Ultraviolet and Visible (TUV) model. The results show that a pronounced spectral and temporal variability in the AOD during three lockdown phases is mainly due to distinct aerosol sources. The increase in AOD during LDP2 due to long-range transport can bring large amounts of mineral dust and smoke aerosols from the west Asian region and central India, and which is reasonably consistent with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) air mass back trajectories and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts analysis over the measurement location. Overall, a drastic reduction in BC concentration (~8.4%) and AOD (10.8%) were observed in the semi-arid area during LDP1 with correspondence to PLD. The columnar aerosol size distributions retrieved from the spectral AODs followed power-law plus unimodal during three phases. The absorption angstrom exponent (AAE) analysis reveals a predominant contribution to the BC from biomass burning activities during the lockdown period over the measurement location.</p></div>","PeriodicalId":15096,"journal":{"name":"Journal of Atmospheric and Solar-Terrestrial Physics","volume":"212 ","pages":"Article 105491"},"PeriodicalIF":1.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jastp.2020.105491","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10375376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}