Stratospheric Ozone Concentrations Research Articles

Temperature differentially regulates estuarine microbial N2O production along a salinity gradient

Nitrous oxide (N2O) is atmospheric trace gas that contributes to climate change and affects stratospheric and ground-level ozone concentrations. Ammonia oxidizers and denitrifiers contribute to N2O emissions in estuarine waters. However, as an important climate factor, how temperature regulates microbial N2O production in estuarine water remains unclear. Here, we have employed stable isotope labeling techniques to demonstrate that the N2O production in estuarine waters exhibited differential thermal response patterns between nearshore and offshore regions. The optimal temperatures (Topt) for N2O production rates (N2OR) were higher at nearshore than offshore sites. 15N-labeled nitrite (15NO2-) experiments revealed that at the nearshore sites dominated by ammonia-oxidizing bacteria (AOB), the thermal tolerance of 15N-N2OR increases with increasing salinity, suggesting that N2O production by AOB-driven nitrifier denitrification may be co-regulated by temperature and salinity. Metatranscriptomic and metagenomic analyses of enriched water samples revealed that the denitrification pathway of AOB is the primary source of N2O, while clade II N2O-reducers dominated N2O consumption. Temperature regulated the expression patterns of nitrite reductase (nirK) and nitrous oxide reductase (nosZ) genes from different sources, thereby influencing N2O emissions in the system. Our findings contribute to understanding the sources of N2O in estuarine waters and their response to global warming.

The impact of El Niño–Southern Oscillation on the total column ozone over the Tibetan Plateau

Abstract. The Tibetan Plateau (TP; approximately 27.5–37.5° N, 75.5–105.5° E) is the highest and largest plateau on Earth with a mean elevation of over 4 km. This special geography causes strong surface solar ultraviolet radiation (UV), with potential risks to human and ecosystem health, which is mainly controlled by the local stratospheric ozone concentration. The El Niño–Southern Oscillation (ENSO), the dominant mode of interannual variability on Earth, is characterised by the tropical Pacific Ocean sea surface temperature anomalies (SSTAs) and sea level pressure change for the warm-phase El Niño and cold-phase La Niña events. Although some studies have suggested the existence of positive correlation between ENSO and the total column ozone (TCO) over the TP, the mechanism underlying this effect is not fully understood. Here we use the Copernicus Climate Change Service (C3S) merged satellite dataset, the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) dataset and the TOMCAT three-dimensional (3D) offline chemical transport model forced by ERA5 meteorological reanalyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) over the period 1979–2021 to investigate the influence of ENSO on the TCO over the TP. We find that the El Niño (La Niña) events favour positive (negative) TCO anomalies over the TP from wintertime of its mature phase to springtime of its decaying phase. Through studying the ozone profile, we attribute the positive (negative) TCO anomalies mainly to the increased (decreased) ozone at the 200–70 hPa levels, i.e. in the upper troposphere and lower stratosphere (UTLS) regions. Our results suggest that the El Niño events impact the TP TCO via the following potential processes: (1) a negative upper-level geopotential height anomaly associated with El Niño is responsible for a decrease in air column thickness; (2) the thickness decrease modulates reduced tropospheric temperature and thus favours a decrease in the tropopause height (TH); and (3) such a TH decrease tends to induce a change in the relative amounts of ozone-poor tropospheric and ozone-rich stratospheric air in the profile, which increases the partial column ozone in the UTLS and hence corresponds to the TP TCO increase. The La Niña events affect TP TCO in a manner resembling the El Niño events, except with anomalies of opposite sign. This work provides a systematic understanding of the influence of ENSO on ozone over the TP, which has implications for the interannual variability of ozone.

Climate factors associated with cancer incidence: An ecological study covering 33 cancers from population-based registries in 37 countries

Cancer etiology is multifactorial, with climate change and environmental factors such as extreme weather events and ozone layer destruction potentially increasing cancer risk. Investigating climate factors with cancer incidence can provide valuable insights for prevention and future disease burden prediction. We conducted a population-based ecological study using data from the World Health Organization’s Cancer Incidence in Five Continents (CI5plus, 89 cancer registries from 1998 to 2012) and the Surveillance, Epidemiology, and End Results (SEER, 607 US counties from 2000 to 2018) Program. We tracked climate factors through satellite-based remote sensing, including green space, stratospheric ozone concentration, solar radiation, precipitation, and temperature. We performed linear panel regression models to estimate the effects of both long-term exposure, lag effect, and change rate of climate factors on cancer incidences. We adjusted for smoking prevalence, air pollution, and gross domestic product (GDP) per capita to account for potential confounding factors. Our study included more than 430 million underlying populations across 37 countries. Higher green space exposure (per 0.1-unit normalized difference vegetation index, NDVI) was associated with decreased incidence of lung cancer (up to 6.66 cases [95%CI 4.38–8.93] per 100,000) and prostate cancer (up to 10.84 cases [95% CI 7.73–13.95] per 100,000). Increased solar radiation was associated with a higher incidence of melanoma, but a lower incidence of prostate cancer. No evidence was found to suggest associations between temperature or precipitation and cancer incidence. However, a rapid increase in temperature was linked to higher incidences of corpus uteri cancer and melanoma. Long-term exposure and rapid changes in climate factors may influence changes in cancer incidence, particularly lung and prostate cancers. While some associations were supported by existing evidence (such as solar radiation and melanoma), further research is necessary to investigate the etiology of novel cancer risk factors.

Solar FTIR measurements of NOx vertical distributions – Part 1: First observational evidence of a seasonal variation in the diurnal increasing rates of stratospheric NO2 and NO

Abstract. Observations of nitrogen dioxide (NO2) and nitrogen oxide (NO) in the stratosphere are relevant to understand long-term changes and variabilities in stratospheric nitrogen oxide (NOx) and ozone (O3) concentrations. Due to the versatile role of NO2 and NO in stratospheric O3 photochemistry, they are important for recovery and build-up of O3 holes in the stratosphere and therefore can indirectly affect human life. Thus, we present in this work the evaluation of NO2 and NO stratospheric partial columns (> 16 km altitude) retrieved from ground-based Fourier-transform infrared (FTIR) measurements of over 25 years at Zugspitze (47.42° N, 10.98° E; 2964 m a.s.l.) and 18 years at Garmisch (47.47° N, 11.06° E; 745 m a.s.l.), Germany. The obtained stratospheric columns are only weakly influenced by tropospheric pollution and show only a very small bias of 2.5 ± 0.2 % when comparing NO2 above Zugspitze and Garmisch. Stratospheric columns of both NO2 and NO show a diurnal increase that depends on local solar time (LST). We quantified this behavior by calculating diurnal increasing rates. Here, we find mean values for the NO2 diurnal increasing rate of (0.89 ± 0.14) × 1014 and (0.94 ± 0.14) × 1014 cm−2 h−1 at Zugspitze and Garmisch, respectively. The mean NO morning diurnal increasing rate above Zugspitze is found to be (1.42 ± 0.12) × 1014 cm−2 h−1. Regarding the seasonal dependency of these increasing rates, for the first time, we were able to experimentally detect a significant seasonal variation in both NO2 diurnal increasing rates and NO morning diurnal increasing rates with a maximum of (1.13 ± 0.04) × 1014 cm−1 h−1 for NO2 and (1.76 ± 0.25) × 1014 cm−1 h−1 for NO in September and a minimum of (0.71 ± 0.18) × 1014 cm−1 h−1 in December for NO2 and a minimum of (1.18 ± 0.41) × 1014 cm−1 h−1 in November for NO. This similar behavior may be explained by the interconnection of both species in stratospheric photochemistry. The outcome of this work is a retrieval and analysis strategy of FTIR data for NOx stratospheric columns, which can help to further validate photochemical models or improve satellite validations. The first use of this data set is shown in the companion paper (Nürnberg et al., 2023) wherein experiment-based NOx scaling factors describing the diurnal increase in the retrieved partial columns are extracted and recently published model-based scaling factors are validated.

Stratospheric Warming Events in the Period January–March 2023 and Their Impact on Stratospheric Ozone in the Northern Hemisphere

In this investigation, a comparison is presented between variations in temperature and ozone concentration at different altitude levels in the stratosphere for the Northern Hemisphere in the conditions of Sudden Stratospheric Warming (SSW) for the period January–March 2023. Spatial and altitude distribution of atmospheric characteristics derived from MERRA-2 are represented by their Fourier decomposition. A cross-correlation analysis between temperature and Total Ozone Column (TOC) is used. The longitudinal inhomogeneities in temperature, caused by stationary Planetary Waves with wavenumber 1 (SPW1), are found to be significant at altitudes around the maximum of the maximum of the ozone number density vertical distribution. As a result, it is established that the latitudinal and longitudinal distribution of TOC has a noticeable similarity with that of the temperature at altitudes close to the ozone concentration maximum. The results of correlation between temperature at individual stratospheric levels and ozone concentration show that (i) in the region around the ozone concentration maximum, the correlation is high and positive, (ii) at higher altitudes the sign of the correlation changes to negative (~37 km). The examination shows that the anomalous increases in TOC during SSW are due to an increase in ozone concentration in the altitudes between 10 km and 15 km.

Stratospheric Ozone Content Variations Over the City of Obninsk from Data of Lidar and Satellite Measurements

Stratospheric Ozone Content Variations Over the City of Obninsk from Data of Lidar and Satellite Measurements

Stratospheric Ozone Variations Over Obninsk from Data of Lidar and Satellite Measurements

Analysis of variations of stratospheric ozone content at 13–18, 18–23 and 23–30 km layers is presented from data of lidar and satellite measurements in 2014–2022 over Obninsk city (55.1° N, 36.6° E). Modeling of deviations from seasonal run for separate quarters of year are fulfilled by using of linear regression method. Impact factors under consideration are quasi-biennial oscillation of zonal wind in tropical stratosphere (QBO), Arctic oscillation (AO), El-Nino – Southern oscillation (ENSO), solar activity (SA), volcanic aerosol (VA) and polar stratospheric clouds (PSC). Enhancement of ozone content is observed in eastern QBO phase at 18–30 km layer (I–II quarter) and in western QBO phase at 13–23 km layer (IV quarter). At separate layers it is revealed significant impacts of AO (II–III quarters), SA (I–II quarters) and VA (III–IV). During a year influence of PSC is originally showed in II quarter at 13–18 layer and then in IV quarter at 13–18 layer. Possible physical mechanisms are discussed which are the basis of the correlation relations observed.

Changes in stratospheric ozone concentrations shape air temperature distributions on the Antarctic Peninsula

Changes in stratospheric ozone concentrations shape air temperature distributions on the Antarctic Peninsula

Regression-based Analysis of Ozone Layer via Machine Learning Models

Ozone protects the livings on the earth from ultraviolet radiation. The emission of ozone depleting substance causes the Antarctic ozone hole and reduces the ultraviolet radiation absorption rate by ozone layer. Researchers find that ozone depleting substances (ODS) accounts for ozone concentration between 9 km and 25km, by chemical-climate models and ozone concentration will increase by 15% until 2050. In this work, we used six major ODS consumption worldwide and mean stratospheric ozone concentration each year. Seven regression models are implemented to make prediction and k-fold cross validation is used for avoiding overfitting. Root mean squared error (RMSE), and standard deviation are two performance metrics of regression models. The results indicate that the prediction from support vector regression achieved the lowest RMSE. Random forester and k-nearest neighbor are also appropriate for make prediction. We also concluded that linear, polynomial, ridge, and lasso regression methods are hardly to fit the data in this application.

Sun CubE OnE: A multi-wavelength synoptic solar micro satellite

The Sun cubE onE (SEE) is a 12U CubeSat mission proposed for a phase A/B study to the Italian Space Agency that will investigate Gamma and X-ray fluxes and ultraviolet (UV) solar emission to support studies in Sun-Earth interaction and Space Weather from LEO. More in detail, SEE’s primary goals are to measure the flares emission from soft-X to Gamma ray energy range and to monitor the solar activity in the Fraunhofer Mg II doublet at 280 nm, taking advantage of a full disk imager payload. The Gamma and X-ray fluxes will be studied with unprecedented temporal resolution and with a multi-wavelength approach thanks to the combined use of silicon photodiode and silicon photomultiplier (SiPM) -based detectors. The flare spectrum will be explored from the keV to the MeV range of energies by the same payload, and with a cadence up to 10 kHz and with single-photon detection capabilities to unveil the sources of the solar flares. The energy range covers the same bands used by GOES satellites, which are the standard bands for flare magnitude definition. At the same time SiPM detectors combined with scintillators allow to cover the non-thermal bremsstrahlung emission in the gamma energy range. Given its UV imaging capabilities, SEE will be a key space asset to support detailed studies on solar activity, especially in relation to ultraviolet radiation which strongly interacts with the upper layers of the Earth’s atmosphere, and in relation to space safety, included in the field of human space exploration. The main goal for the UV payload is to study the evolution of the solar UV emission in the Mg II band at two different time scales: yearly variations along the solar cycle and transient variations during flare events. The Mg II index is commonly used as a proxy of the solar activity in the Sun-as-a-star paradigm, in which solar irradiance variations in the UV correlate with the variations in stratospheric ozone concentrations and other physical parameters of the Earth high atmosphere. SEE data will be used together with space and ground-based observatories that provide Solar data (e.g. Solar Orbiter, IRIS, GONG, TSST), high energy particle fluxes (e.g. GOES, MAXI, CSES) and geomagnetic data in a multi-instrument/multi-wavelength/multi-messenger approach.

Analysis of Vertical Distribution of Ozone in Winter and Its Transport from Stratosphere to Troposphere in the Pearl River Delta Region of China

The vertical distribution of winter ozone in the Pearl River Delta in 2021 was analyzed using electrochemical concentration cell (ECC) ozonesonde and compared with the ozone Light detection and ranging (LiDAR) data. The transport of stratospheric ozone to the troposphere was also explored. The results show that (1) the maximum value of the stratospheric ozone layer was about 25 km. The stratospheric ozone profile is mainly unimodal, and the stratospheric ozone content was much higher than that of the troposphere. In the troposphere, the ozone content near the ground (0-2 km) was slightly higher than that between 5 and 15 km. The ozone profile in the upper and middle troposphere showed a peak structure, which was mainly divided into single peak (22%) and multipeak (77%) profiles. (2) In the middle and lower troposphere, the vertical profile of ozone detected by LiDAR is significantly different from that detected by sounding system. The difference between the two ranged from 10 ppb to 60 ppb at the same height. Ozone sounding can supplement the blind area of the near-ground layer by LiDAR ozone detection and can calibrate the inversion results of LiDAR. (3) On January 5, 2022, stratospheric ozone was transported to the troposphere. The stratospheric intrusion occurred due the high wind speed of the subtropical jet centre over Qingyuan and due to strong subsidence movement. When the stratospheric air mass moved to the troposphere, and subsidence airflow encountered, the ozone concentration near the ground was rapidly increased in a short time. It was identified as an “exceptional event.”

The features of haloacetic acid oxidation that contribute to stratospheric ozone depletion

Environmental context Due to The Montreal Protocol, stratospheric ozone concentration is slowly regenerating, however, the recovery rate is slower than predicted by photochemical models. FTIR spectroscopy together with quantum chemical calculations confirmed that ozone reacts with halogenated acids adsorbed at a model aerosol surface. Reactions occur at low temperatures without photochemical activation with formation of halogen oxides that are known to promote catalytic cycles of ozone depletion. Abstract The present work addresses the problem of stratospheric ozone depletion. While gas phase and photochemically induced reactions of ozone are well studied, the mechanisms of heterogeneous O3 interactions with different halogenated species still remain uncertain. An in situ FTIR investigation of low-temperature heterogeneous reactions of ozone and haloacetic acids in conditions close to stratospheric was performed and supported by ab initio quantum chemical calculations. Products of ozone reaction with differently chlorine and bromine-substituted acetic acids were identified and possible reactions pathways were suggested. Ozone can attach to a carbon atom to release a halogen atom that forms a halogen oxide. Halogen oxide in its turn can take part in the catalytic cycles of ozone depletion. Suggested reaction pathways leading to the additional release of the chlorine oxides can enhance the atmospheric models that calculate ozone concentration.

Fossil pigments and environmental conditions in the oligotrophic Laja Lake in the Chilean Andes

Interactions among climate change, ozone depletion, and ultraviolet radiation affect aquatic ecosystems. Meteorological and biological monitoring is often too brief, however, to record the magnitudes of past changes in ultraviolet fluxes and their effects. This study presents an analysis of fossil pigments and environmental conditions in the oligotrophic Laja Lake in the Chilean Andes over a 60-year period. The age of the sediment core was determined using high-efficiency gamma spectrometry and dated with lead-210 (210Pb). Analysis of the total and specific fossil pigments from a sediment core utilized a combination of analytical methods, spectrophotometry, and high-performance liquid chromatography. Environmental variables, such as stratospheric ozone concentration, temperature, precipitation, and ultraviolet radiation explained changes in the fossil pigment scytonemin. Results showed that low cloud cover over the high mountain lake predominated, with high ultraviolet radiation and temperature values during summer months. The most abundant group was Bacillariophyceae (diatoms). The highest concentrations of the pigments (canthaxanthin echinenone, myxoxanthophyll, aphanizophyll zeaxanthin and scytonemin) that represent the cyanobacteria groups were found in the upper part of the core (cm 0–15). The trend analysis further suggested that the influence of environmental features enabled generation of ultraviolet radiation-shielding pigment in the algae communities in the high mountain lake.This study advances understanding of the interactive effects of climate change, ozone depletion, and ultraviolet radiation on aquatic ecosystems. Fossil pigments proved to be good indicators of lake-ecosystem response to climate/environmental changes, which are necessary for predicting possible effects of future climate change.

Twenty-first-century Southern Hemisphere impacts of ozone recovery and climate change from the stratosphere to the ocean

Abstract. Changes in stratospheric ozone concentrations and increasing concentrations of greenhouse gases (GHGs) alter the temperature structure of the atmosphere and drive changes in the atmospheric and oceanic circulation. We systematically investigate the impacts of ozone recovery and increasing GHGs on the atmospheric and oceanic circulation in the Southern Hemisphere during the twenty-first century using a unique coupled ocean–atmosphere climate model with interactive ozone chemistry and enhanced oceanic resolution. We use the high-emission scenario SSP5-8.5 for GHGs under which the springtime Antarctic total column ozone returns to 1980s levels by 2048 in our model, warming the lower stratosphere and strengthening the stratospheric westerly winds. We perform a spatial analysis and show for the first time that the austral spring stratospheric response to GHGs exhibits a marked planetary wavenumber 1 (PW1) pattern, which reinforces the response to ozone recovery over the Western Hemisphere and weakens it over the Eastern Hemisphere. These changes, which imply an eastward phase shift in the PW1, largely cancel out in the zonal mean. The Southern Hemisphere residual circulation strengthens during most of the year due to the increase in GHGs and weakens in spring due to ozone recovery. However, we find that in November the GHGs also drive a weakening of the residual circulation, reinforcing the effect of ozone recovery, which represents another novel result. At the surface, the westerly winds weaken and shift equatorward due to ozone recovery, driving a weak decrease in the transport of the Antarctic Circumpolar Current and in the Agulhas leakage and a cooling of the upper ocean, which is most pronounced in the latitudinal band 35–45∘ S. The increasing GHGs drive changes in the opposite direction that overwhelm the ozone effect. The total changes at the surface and in the oceanic circulation are nevertheless weaker in the presence of ozone recovery than those induced by GHGs alone, highlighting the importance of the Montreal Protocol in mitigating some of the impacts of climate change. We additionally compare the combined effect of interactively calculated ozone recovery and increasing GHGs with their combined effect in an ensemble in which we prescribe the CMIP6 ozone field. This second ensemble simulates a weaker ozone effect in all the examined fields, consistent with its weaker increase in ozone. The magnitude of the difference between the simulated changes at the surface and in the oceanic circulation in the two ensembles is as large as the ozone effect itself. This shows the large uncertainty that is associated with the choice of the ozone field and how the ozone is treated.

Impact of the Stratospheric Ozone on the Northern Hemisphere Surface Climate During Boreal Winter

AbstractIn this study, we examine the impact of stratospheric ozone on the Northern Hemisphere (NH) surface climate during boreal winter by analyzing the two experiments using Global/Regional Integrated Model system‐Chemistry Climate Model (GRIMs‐CCM) (i.e., LINOZ‐on/‐off experiments) and eight Atmosphere Model Inter‐comparison Project (AMIP) climate models. In LINOZ‐on, ozone concentration in the upper troposphere and lower stratosphere (UTLS) varies with latitudes, being low in the tropics and high in the mid‐to‐high‐latitudes, by adopting a linearized ozone scheme. The LINOZ‐off, however, prescribes constant ozone concentration throughout all latitudes. Cooler surface temperatures over the Eurasian and Asian continents in boreal winter are simulated in LINOZ‐on than that in LINOZ‐off. A reduced mean UTLS temperature gradient in LINOZ‐on, due to the difference of climatological mean ozone concentration, causes a weakened mean zonal wind in the lower stratosphere compared to the LINOZ‐off. This mean wind difference is extended all the way to the surface, resulting in a negative Arctic Oscillation (AO)‐like mean state in the mid‐to‐high latitudes in the LINOZ‐on. Subsequently, it causes cool surface temperatures over the Eurasian and Asian continents by altering horizontal winds. This result is also supported by the comparison between AMIP models with a relatively high and low stratospheric ozone concentration in the mid‐to‐high latitudes. Therefore, a careful attention should be paid to the climatology of stratospheric ozone concentration in climate models to correctly simulate surface climate in the NH in the past and future climate.

Fifty years of balloon-borne ozone profile measurements at Uccle, Belgium: a short history, the scientific relevance, and the achievements in understanding the vertical ozone distribution

Abstract. Starting in 1969 and comprising three launches a week, the Uccle (Brussels, Belgium) ozonesonde dataset is one of longest and densest in the world. Moreover, as the only major change was the switch from Brewer-Mast (BM) to electrochemical concentration cell (ECC) ozonesonde types in 1997 (when the emissions of ozone-depleting substances peaked), the Uccle time series is very homogenous. In this paper, we briefly describe the efforts that were undertaken during the first 3 decades of the 50 years of ozonesonde observations to guarantee the homogeneity between ascent and descent profiles, under changing environmental conditions (e.g. SO2), and between the different ozonesonde types. This paper focuses on the 50-year-long Uccle ozonesonde dataset and aims to demonstrate its past, present, and future relevance to ozone research in two application areas: (i) the assessment of the temporal evolution of ozone from the surface to the (middle) stratosphere, and (ii) as the backbone for validation and stability analysis of both stratospheric and tropospheric satellite ozone retrievals. Using the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) multiple linear regression model (SPARC/IO3C/GAW, 2019), we found that the stratospheric ozone concentrations at Uccle have declined at a significant rate of around 2 % per decade since 1969, which is also rather consistent over the different stratospheric levels. This overall decrease can mainly be assigned to the 1969–1996 period with a rather consistent rate of decrease of around −4 % per decade. Since 2000, a recovery of between +1 % per decade and +3 % per decade of the stratospheric ozone levels above Uccle has been observed, although it is not significant and is not seen for the upper stratospheric levels measured by ozonesondes. Throughout the entire free troposphere, a very consistent increase in the ozone concentrations of 2 % per decade to 3 % per decade has been measured since both 1969 and 1995, with the trend since 1995 being in almost perfect agreement with the trends derived from the In-service Aircraft for a Global Observing System (IAGOS) ascent/descent profiles at Frankfurt. As the number of tropopause folding events in the Uccle time series has increased significantly over time, increased stratosphere-to-troposphere transport of recovering stratospheric ozone might partly explain these increasing tropospheric ozone concentrations, despite the levelling-off of (tropospheric) ozone precursor emissions and notwithstanding the continued increase in mean surface ozone concentrations. Furthermore, we illustrate the crucial role of ozonesonde measurements for the validation of satellite ozone profile retrievals. With the operational validation of the Global Ozone Monitoring Experiment-2 (GOME-2), we show how the Uccle dataset can be used to evaluate the performance of a degradation correction for the MetOp-A/GOME-2 UV (ultraviolet) sensors. In another example, we illustrate that the Microwave Limb Sounder (MLS) overpass ozone profiles in the stratosphere agree within ±5 % with the Uccle ozone profiles between 10 and 70 hPa. Another instrument on the same Aura satellite platform, the Tropospheric Emission Spectrometer (TES), is generally positively biased with respect to the Uccle ozonesondes in the troposphere by up to ∼ 10 ppbv, corresponding to relative differences of up to ∼ 15 %. Using the Uccle ozonesonde time series as a reference, we also demonstrate that the temporal stability of those last two satellite retrievals is excellent.

Study of Variability of Atmospheric Ozone over Jumla in Half Period of 24 Solar Cycle

This paper reports the variation of total ozone column (TOC) over Jumla (Lat.:-29.28° N, Long.:-82.16° E and Alt.:- 2300 m above sea level) from 2008 to 2014 derived from Total Ozone Mapping Spectrometer (TOMS) satellite observations. The monthly, seasonal, annual variations of TOC, solar insolation and clearness index have been analyzed. The result exemplifies that during the whole study period, the maximum value of monthly average TOC is 289.21 DU ± 10.75 DU in April, while the minimum value is 257.23 DU ± 11.25 DU in December. The results also show that TOC is highly seasonal dependent with larger TOC in spring 273.68 DU ± 14.92 DU and lower in the winter season (260.68 DU ± 15.25 DU). The average annual value of TOC exhibits slightly variable with a maximum in 2010 (277.52 DU ± 40.64 DU) and minimum in 2008 (267.19 DU ± 11.11 DU). The average values of solar insolation and clearness index for whole study the period are 5.10 86 kWh/m2/day ± 0.86 kWh/m2/day and 0.59 ± 0.12 respectively. The average value of TOC during the whole study period is 271.84 DU ± 14.19 DU, which indicates a good amount of stratospheric ozone content over Jumla.

Effects of elevated humidity on stratospheric ozone content in the tropics

This study examines the effects of elevated humidity on stratospheric ozone content in the tropics, a case study of Nigeria. The specific stations in Nigeria studied with their co-ordinate include Makurdi (7.7°N 8.5°E), Maiduguri (11.9°N 13.2°E), Kano (12.0°N 8.5°E), Port-Harcourt (4.9°N 7.0°E) and Lagos (6.5°N 3.4°E). Using monthly mean stratospheric ozone data from Earth Probe Total Ozone Mass Spectroscopy (EPTOMS) together with humidity and temperature data from the Nigerian Meteorological Agency (NIMET), studies were carried out over the five stations for a period of fifteen years (1998-2012). The results show that elevated humidity cools the stratosphere, slowing down the rate of chemical reactions that destroy ozone, thereby resulting to more ozone amount. Ozone variation is latitude dependent with more variations in station observed in the north. Using Spearman’s Rank Correlation Coefficient analysis, it was equally observed that ozone and temperature are strongly anti-correlated in Port Harcourt, Makurdi and Lagos stations (r = -0.8531, -0.7832, and -0.8759, respectively); and positively correlated in Maiduguri and Kano stations (r = 0.3776 and 0.4965, respectively). The positive correlation may be attributed to the high dehydration of water vapor in those stations. Results also revealed that ozone and humidity are positively correlated (r = 0.9073, 0.9021, 0.7133, 0.7552, and 0.7692), for Port Harcourt, Makurdi, Maiduguri, Lagos, and Kano. Both ozone and humidity attain maximum during wet season and minimum during the dry season in Nigeria. The implication of more humidity in the wet season is due to the evaporation of raindrops and surface puddles. The implication of more ozone concentration in the wet season may be attributed to the transportation of ozone from the influence of Brewer-Dobson Circulation (BDC). Again it was found out that temperature and humidity are negatively correlated. Consequently, our findings show that, at elevated humidity, the surface temperature is low with more stratospheric ozone content. Key words: Humidity, stratospheric ozone, temperature, rainfall.

Impacts of Stratospheric Ozone Extremes on Arctic High Cloud

AbstractStratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, because of its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry–climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ozone-depleting substances (ODS) emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may contribute to enhanced Arctic surface warming in spring through a positive longwave cloud radiative effect. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion, and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.

Stratospheric impact on the Northern Hemisphere winter and spring ozone interannual variability in the troposphere

Abstract. In this study we use ozone and stratospheric ozone tracer simulations from the high-resolution (0.5∘×0.5∘) Goddard Earth Observing System, Version 5 (GEOS-5), in a replay mode to study the impact of stratospheric ozone on tropospheric ozone interannual variability (IAV). We use these simulations in conjunction with ozonesonde measurements from 1990 to 2016 during the winter and spring seasons. The simulations include a stratospheric ozone tracer (StratO3) to aid in the evaluation of the impact of stratospheric ozone IAV on the IAV of tropospheric ozone at different altitudes and locations. The model is in good agreement with the observed interannual variation in tropospheric ozone, except for the post-Pinatubo period (1992–1994) over the region of North America. Ozonesonde data show a negative ozone anomaly in 1992–1994 following the Pinatubo eruption, with recovery thereafter. The simulated anomaly is only half the magnitude of that observed. Our analysis suggests that the simulated stratosphere–troposphere exchange (STE) flux deduced from the analysis might be too strong over the North American (50–70∘ N) region after the Mt. Pinatubo eruption in the early 1990s, masking the impact of lower stratospheric ozone concentration on tropospheric ozone. European ozonesonde measurements show a similar but weaker ozone depletion after the Mt. Pinatubo eruption, which is fully reproduced by the model. Analysis based on the stratospheric ozone tracer identifies differences in strength and vertical extent of stratospheric ozone impact on the tropospheric ozone interannual variation (IAV) between North America and Europe. Over North American stations, the StratO3 IAV has a significant impact on tropospheric ozone from the upper to lower troposphere and explains about 60 % and 66 % of the simulated ozone IAV at 400 hPa and ∼11 % and 34 % at 700 hPa in winter and spring, respectively. Over European stations, the influence is limited to the middle to upper troposphere and becomes much smaller at 700 hPa. The Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), assimilated fields exhibit strong longitudinal variations over Northern Hemisphere (NH) mid-high latitudes, with lower tropopause height and lower geopotential height over North America than over Europe. These variations associated with the relevant variations in the location of tropospheric jet flows are responsible for the longitudinal differences in the stratospheric ozone impact, with stronger effects over North America than over Europe.