scholarly journals Climatological Study of Ozone over Saudi Arabia

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1275
Author(s):  
Saleha Al-Kallas ◽  
Motirh Al-Mutairi ◽  
Heshmat Abdel Basset ◽  
Abdallah Abdeldym ◽  
Mostafa Morsy ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Abrupt Change ◽  
Kendall Test ◽  
Positive Trend ◽  
Kingdom Of Saudi Arabia ◽  
Total Column Ozone ◽  
The North ◽  
Column Ozone ◽  
Total Column

In this work, analysis of the variability of total column ozone (TCO) over the Kingdom of Saudi Arabia (KSA) has been conducted during the 1979–2020 period based on the ECMWF-ERA5 dataset. It is found that the highest values of TCO appear in the spring and winter months especially over north KSA, while the lowest values of TCO occur in the autumn months. The highest values of the coefficient of variation (COV) for TCO occur in winter and spring as they gradually decrease southward, while the lowest COV values appear in summer and autumn. The Mann–Kendall test indicates that the positive trend values are dominant for the annual and seasonal TCO values over KSA, and they gradually increase southward. The study of long-term variability of annual TCO at KSA stations shows negative trend values are the dominant behavior during the 1979–2004 period, while positive trend values are the dominant behavior during the 2004–2020 period. The Mann–Whitney test assessed the abrupt change of the annual TCO time series at 28 stations in KSA and confirmed that there is an abrupt change towards increasing values around 2000, 2005, and 2014. The climatological monthly mean of the ozone mass mixing ratio (OMR) is studied at three stations representing the north, middle, and south of KSA. The highest values of OMR are found in the layer between 20 and 4 hPa with the maximum in summer and early autumn, while the lowest values are found below 100 hPa.

scholarly journals Analysis and attribution of total column ozone changes over the Tibetan Plateau during 1979–2017

2020 ◽  
Vol 20 (14) ◽  
pp. 8627-8639 ◽  
Author(s):  
Yajuan Li ◽  
Martyn P. Chipperfield ◽  
Wuhu Feng ◽  
Sandip S. Dhomse ◽  
Richard J. Pope ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Regression Models ◽  
Positive Trend ◽  
The Tibetan Plateau ◽  
Total Column Ozone ◽  
Latitude Band ◽  
Ozone Trends ◽  
Column Ozone ◽  
Total Column

Abstract. Various observation-based datasets have confirmed positive zonal mean column ozone trends at midlatitudes as a result of the successful implementation of the Montreal Protocol. However, there is still uncertainty about the longitudinal variation of these trends and the direction and magnitude of ozone changes at low latitudes. Here, we use the extended Copernicus Climate Change Service (C3S) dataset (1979–2017) to investigate the long-term variations in total column ozone (TCO) over the Tibetan Plateau (TP) for different seasons. We use piecewise linear trend (PWLT) and equivalent effective stratospheric chlorine loading (EESC)-based multivariate regression models with various proxies to attribute the influence of dynamical and chemical processes on the TCO variability. We also compare the seasonal behaviour of the relative total ozone low (TOL) over the TP with the zonal mean at the same latitude. Both regression models show that the TP column ozone trends change from negative trends from 1979 to 1996 to small positive trends from 1997 to 2017, although the later positive trend based on PWLT is not statistically significant. The wintertime positive trend starting from 1997 is larger than that in summer, but both seasonal TP recovery rates are smaller than the zonal means over the same latitude band. For TP column ozone, both regression models suggest that the geopotential height at 150 hPa (GH150) is a more suitable and realistic dynamical proxy compared to a surface temperature proxy used in some previous studies. Our analysis also shows that the wintertime GH150 plays an important role in determining summertime TCO over the TP through persistence of the ozone signal. For the zonal mean column ozone at this latitude, the quasi-biennial oscillation (QBO) is nonetheless the dominant dynamical proxy. We also use a 3-D chemical transport model to diagnose the contributions of different proxies for the TP region. The role of GH150 variability is illustrated by using two sensitivity experiments with repeating dynamics of 2004 and 2008. The simulated ozone profiles clearly show that wintertime TP ozone concentrations are largely controlled by tropics to midlatitude pathways, whereas in summer variations associated with tropical processes play an important role. These model results confirm that the long-term trends of TCO over the TP are dominated by different processes in winter and summer. The different TP recovery rates relative to the zonal means at the same latitude band are largely determined by wintertime dynamical processes.

scholarly journals Ozone Variability over Egypt

2017 ◽  
Author(s):  
Ayman Badawy ◽  
Heshmat Abdel Basset ◽  
Mohamed Eid
Keyword(s):  
Time Series ◽  
Abrupt Change ◽  
Kendall Test ◽  
Horizontal Distribution ◽  
The Other ◽  
Positive Trend ◽  
The North ◽  
Seasonal Time Series ◽  
Ozone Trend

The variability of ozone over Egypt has been studied in this work. Higher values of coefficient of variation (COV) at eight stations occur at winter while lowest values occur at summer. The COV is function of latitude in annual, winter and spring where it decreases gradually from the north to south of Egypt. The trend analysis of ozone over the eight stations indicates negative trends over northern stations for both annual and seasonal time series with the greatest one at winter. The horizontal distribution of ozone trend values is negative over all Egypt in winter while it positive over middle and south Egypt in the other seasons. The long-term variability of the behavior of the annual ozone shows positive trend values in ozone are the dominant features during the period 1979- 1989 at the most stations. Negative trend values in ozone are the dominant features during the period 1990- 2014 at all stations. The Mann–Kendall test confirms that there is an abrupt change towards decreasing of ozone occurs in 1981, 1984, 2012, 1999, 2000, 1998 and 2010, while a change towards increasing of ozone appears in 2006, 2014, 1993 and 1989.

scholarly journals Spatial mapping of ground-based observations of total ozone

2015 ◽  
Vol 8 (10) ◽  
pp. 4487-4505 ◽  
Author(s):  
K.-L. Chang ◽  
S. Guillas ◽  
V. E. Fioletov
Keyword(s):  
Spatial Interpolation ◽  
Stochastic Partial Differential Equation ◽  
Positive Impact ◽  
The Novel ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Source Of Information ◽  
Total Column ◽  
Ozone Levels

Abstract. Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with the covariance-based kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to the covariance-based kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

scholarly journals Spatial mapping of ground-based observations of total ozone

2015 ◽  
Vol 8 (4) ◽  
pp. 3967-4009 ◽  
Author(s):  
K.-L. Chang ◽  
S. Guillas ◽  
V. E. Fioletov
Keyword(s):  
Spatial Interpolation ◽  
Stochastic Partial Differential Equation ◽  
Positive Impact ◽  
The Novel ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Source Of Information ◽  
Total Column ◽  
Ozone Levels

Abstract. Total column ozone variations estimated using ground-based stations provide important independent source of information in addition to satellite-based estimates. This estimation has been vigorously challenged by data inhomogeneity in time and by the irregularity of the spatial distribution of stations, as well as by interruptions in observation records. Furthermore, some stations have calibration issues and thus observations may drift. In this paper we compare the spatial interpolation of ozone levels using the novel stochastic partial differential equation (SPDE) approach with kriging. We show how these new spatial predictions are more accurate, less uncertain and more robust. We construct long-term zonal means to investigate the robustness against the absence of measurements at some stations as well as instruments drifts. We conclude that time series analyzes can benefit from the SPDE approach compared to kriging when stations are missing, but the positive impact of the technique is less pronounced in the case of drifts.

scholarly journals Antarctic ozone depletion between 1960 and 1980 in observations and chemistry–climate model simulations

2016 ◽  
Vol 16 (24) ◽  
pp. 15619-15627 ◽  
Author(s):  
Ulrike Langematz ◽  
Franziska Schmidt ◽  
Markus Kunze ◽  
Gregory E. Bodeker ◽  
Peter Braesicke
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Total Column Ozone ◽  
Antarctic Ozone ◽  
Climate Model Simulations ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry–climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

scholarly journals Future Arctic ozone recovery: the importance of chemistry and dynamics

2016 ◽  
Author(s):  
E. M. Bednarz ◽  
A. C. Maycock ◽  
N. L. Abraham ◽  
P. Braesicke ◽  
O. Dessens ◽  
...  
Keyword(s):  
Polar Vortex ◽  
Lower Atmosphere ◽  
The Arctic ◽  
Relative Role ◽  
Total Column Ozone ◽  
The Future ◽  
Stratospheric Cooling ◽  
Column Ozone ◽  
Total Column

Abstract. Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a 7 member ensemble from the Met Office Unified Model with United Kingdom Chemistry and Aerosols (UM-UKCA) simulating the period 1960-2100. The Arctic mean March total column ozone increases throughout the 21st century at a rate of ~11.5 DU decade-1, and is projected to return to the 1980 level in the late 2030s. However, the integrations show that even past 2060 springtime Arctic ozone can episodically drop by ~50-100 DU below the long-term mean to near present day values. Consistent with the global decline in inorganic chlorine (Cly) over the century, the estimated mean halogen induced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of two between 1981-2000 and 2061-2080. However, in the presence of a cold and strong polar vortex elevated halogen losses well above the long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a radiatively-driven cooling trend modelled in the Arctic winter mid- and upper stratosphere, but there is less consistency across the seven ensemble members in the lower stratosphere (100-50 hPa). This is partly due to an increase in downwelling over the Arctic polar cap in winter, which increases transport of ozone into the polar region as well as drives adiabatic warming that partly offsets the radiatively-driven stratospheric cooling. However, individual years characterised by significantly suppressed downwelling, reduced transport and low temperatures continue into the future. We conclude that despite the future long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue thereby facilitating episodic reductions in springtime ozone columns. Whilst our results suggest that the relative role of dynamical processes for determining Arctic springtime ozone will increase in the future, halogen chemistry will remain a smaller but non-negligible contributor for many decades.

scholarly journals Global distribution and 14-year changes in erythemal irradiance, UV atmospheric transmission, and total column ozone for2005–2018 estimated from OMI and EPIC observations

2020 ◽  
Vol 20 (14) ◽  
pp. 8351-8380
Author(s):  
Jay Herman ◽  
Alexander Cede ◽  
Liang Huang ◽  
Jerald Ziemke ◽  
Omar Torres ◽  
...  
Keyword(s):  
High Altitude ◽  
Global Distribution ◽  
Series Data ◽  
Atmospheric Transmission ◽  
Low Latitude ◽  
Total Column Ozone ◽  
Uv Index ◽  
Column Ozone ◽  
Total Column

Abstract. Satellite data from the Ozone Measuring Instrument (OMI) and Earth Polychromatic Imaging Camera (EPIC) are used to study long-term changes and global distribution of UV erythemal irradiance E(ζ,φ,z,t) (mW m−2) and the dimensionless UV index E ∕ (25 m Wm−2) over major cities as a function of latitude ζ, longitude φ, altitude z, and time t. Extremely high amounts of erythemal irradiance (12 < UV index <18) are found for many low-latitude and high-altitude sites (e.g., San Pedro, Chile, 2.45 km; La Paz, Bolivia, 3.78 km). Lower UV indices at some equatorial or high-altitude sites (e.g., Quito, Ecuador) occur because of persistent cloud effects. High UVI levels (UVI > 6) are also found at most mid-latitude sites during the summer months for clear-sky days. OMI time-series data starting in January 2005 to December 2018 are used to estimate 14-year changes in erythemal irradiance ΔE, total column ozone ΔTCO3, cloud and haze transmission ΔCT derived from scene reflectivity LER, and reduced transmission from absorbing aerosols ΔCA derived from absorbing aerosol optical depth τA for 191 specific cities in the Northern Hemisphere and Southern Hemisphere from 60∘ S to 60∘ N using publicly available OMI data. A list of the sites showing changes at the 1 standard deviation level 1σ is provided. For many specific sites there has been little or no change in E(ζ,φ,z,t) for the period 2005–2018. When the sites are averaged over 15∘ of latitude, there are strong correlation effects of both short- and long-term cloud and absorbing aerosol change as well as anticorrelation with total column ozone change ΔTCO3. Estimates of changes in atmospheric transmission ΔCT (ζ, φ, z, t) derived from OMI-measured cloud and haze reflectivity LER and averaged over 15∘ of latitude show an increase of 1.1±1.2 % per decade between 60 and 45∘ S, almost no average 14-year change of 0.03±0.5 % per decade from 55∘ S to 30∘ N, local increases and decreases from 20 to 30∘ N, and an increase of 1±0.9 % per decade from 35 to 60∘ N. The largest changes in E(ζ,φ,z,t) are driven by changes in cloud transmission CT. Synoptic EPIC radiance data from the sunlit Earth are used to derive ozone and reflectivity needed for global images of the distribution of E(ζ,φ,z,t) from sunrise to sunset centered on the Americas, Europe–Africa, and Asia. EPIC data are used to show the latitudinal distribution of E(ζ,φ,z,t) from the Equator to 75∘ for specific longitudes. EPIC UV erythemal images show the dominating effect of solar zenith angle (SZA), the strong increase in E with altitude, and the decreases caused by cloud cover. The nearly cloud-free images of E(ζ,φ,z,t) over Australia during the summer (December) show regions of extremely high UVI (14–16) covering large parts of the continent. Zonal averages show a maximum of UVI = 14 in the equatorial region seasonally following latitudes where SZA = 0∘. Dangerously high amounts of erythemal irradiance (12 < UV index < 18) are found for many low-latitude and high-altitude sites. High levels of UVI are known to lead to health problems (skin cancer and eye cataracts) with extended unprotected exposure, as shown in the extensive health statistics maintained by the Australian Institute of Health and Welfare and the United States National Institute of Health National Cancer Institute.

scholarly journals Future Arctic ozone recovery: the importance of chemistry and dynamics

2016 ◽  
Vol 16 (18) ◽  
pp. 12159-12176 ◽  
Author(s):  
Ewa M. Bednarz ◽  
Amanda C. Maycock ◽  
N. Luke Abraham ◽  
Peter Braesicke ◽  
Olivier Dessens ◽  
...  
Keyword(s):  
Polar Vortex ◽  
Lower Atmosphere ◽  
The Arctic ◽  
Relative Role ◽  
Total Column Ozone ◽  
The Future ◽  
Stratospheric Cooling ◽  
Column Ozone ◽  
Total Column

Abstract. Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a seven-member ensemble from the Met Office Unified Model with United Kingdom Chemistry and Aerosols (UM-UKCA) simulating the period 1960–2100. The Arctic mean March total column ozone increases throughout the 21st century at a rate of  ∼  11.5 DU decade−1, and is projected to return to the 1980 level in the late 2030s. However, the integrations show that even past 2060 springtime Arctic ozone can episodically drop by  ∼  50–100 DU below the corresponding long-term ensemble mean for that period, reaching values characteristic of the near-present-day average level. Consistent with the global decline in inorganic chlorine (Cly) over the century, the estimated mean halogen-induced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of 2 between the periods 2001–2020 and 2061–2080. However, in the presence of a cold and strong polar vortex, elevated halogen-induced ozone losses well above the corresponding long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a significant cooling trend in the Arctic winter mid- and upper stratosphere, but there is less confidence in the projected temperature trends in the lower stratosphere (100–50 hPa). This is partly due to an increase in downwelling over the Arctic polar cap in winter, which increases transport of ozone into the polar region as well as drives adiabatic warming that partly offsets the radiatively driven stratospheric cooling. However, individual winters characterised by significantly suppressed downwelling, reduced transport and anomalously low temperatures continue to occur in the future. We conclude that, despite the projected long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue in the future, thereby facilitating episodic reductions in springtime ozone columns. Whilst our results suggest that the relative role of dynamical processes for determining Arctic springtime ozone will increase in the future, halogen chemistry will remain a smaller but non-negligible contributor for many decades to come.

scholarly journals The Wave Geometry of Final Stratospheric Warming Events

2021 ◽  
Author(s):  
Amy H. Butler ◽  
Daniela I. V. Domeisen
Keyword(s):  
North Atlantic ◽  
Polar Vortex ◽  
Stratospheric Warming ◽  
Stratospheric Polar Vortex ◽  
Total Column Ozone ◽  
Planetary Scale ◽  
The North ◽  
Downward Influence ◽  
Column Ozone ◽  
Total Column

Abstract. Every spring, the stratospheric polar vortex transitions from its westerly wintertime state to its easterly summertime state due to seasonal changes in incoming solar radiation, an event known as the final stratospheric warming (FSW). While FSWs tend to be less abrupt than reversals of the boreal polar vortex in midwinter, known as sudden stratospheric warming (SSW) events, their timing and characteristics can be significantly modulated by atmospheric planetary-scale waves. Just like SSWs, FSWs have been found to have predictable surface impacts. While SSWs are commonly classified according to their wave geometry, either by how the vortex evolves (whether the vortex displaces off the pole or splits into two vortices) or by the dominant wavenumber of the vortex just prior to the SSW (wave-1 versus wave-2), little is known about the wave geometry of FSW events. We here show that FSW events for both hemispheres in most cases exhibit a clear wave geometry. Most FSWs can be classified into wave-1 or wave-2 events, but wave-3 also plays a significant role in both hemispheres. Additionally, we find that in the Northern Hemisphere, wave-2 events are more likely to occur later in the spring, while in the Southern Hemisphere, wave-1 or wave-2 events show no clear preference in timing. The FSW enhances total column ozone over the pole of both hemispheres during spring, but the spatial distribution of ozone anomalies can be influenced by the wave geometry and the timing of the event. We also describe the stratosphere's downward influence on surface weather following wave-1 and wave-2 FSW events. Significant differences between the tropospheric response to wave-1 and wave-2 FSW events occur over North America and over the Southern Ocean, while no significant differences are found over the North Atlantic region, Europe, and Antarctica.

scholarly journals Total column ozone measurements by the Dobson spectrophotometer at Belsk (Poland) for the period 1963–2019: homogenization and adjustment to the Brewer spectrophotometer

2021 ◽  
Vol 13 (9) ◽  
pp. 4425-4436
Author(s):  
Janusz W. Krzyścin ◽  
Bonawentura Rajewska-Więch ◽  
Janusz Jarosławski
Keyword(s):  
Weather Conditions ◽  
Total Column Ozone ◽  
Long Term Stability ◽  
Ultraviolet Range ◽  
Brewer Spectrophotometer ◽  
World Standard ◽  
Column Ozone ◽  
Total Column ◽  
Dobson Spectrophotometer

Abstract. The total column ozone (TCO3) measurements by the Dobson spectrophotometer (serial no. 84) have been carried out at Belsk station (51∘50′ N, 20∘47′ E), Poland, since 23 March 1963. In total, ∼115 000 intraday manual observations were made by 31 December 2019. These observations were performed for different combinations of double wavelength pairs in the ultraviolet range and observation types, i.e., direct sun (DS), zenith blue (ZB), and zenith cloudy (ZC) depending on weather conditions. The long-term stability of the instrument was supported by frequent (almost every 4 years) intercomparisons with the world standard spectrophotometer. Trend analyses, based on the monthly and yearly averaged TCO3, can be carried out without any additional corrections to the intraday values. To adjust these data to the Brewer spectrophotometer observations, which were also performed at Belsk, a procedure is proposed to account for less accurate Dobson observations under low solar elevation, presence of clouds, and the temperature dependence of ozone absorption. The adjusted time series shows that the Brewer–Dobson monthly averaged differences are in the range of about ±0.5 %. The intraday TCO3 database, divided into three periods (1963–1979, 1980–1999, and 2000–2019), is freely available at https://doi.org/10.1594/PANGAEA.919378 (Rajewska-Więch et al., 2020).

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