On variability of total ozone derived from TOVS data over peninsular Indian sub-continent and adjoining oceanic area

The total ozone derived from TOVS data from NOAA 12 satellite through one step physical retrieval algorithm of International TOVS Processing Package (ITPP) version 5.0 has been used to identify its diurnal, monthly, latitudinal and longitudinal variability during 1998 over the domain Equator to 26° N / 60-100° E. The linkage of maximum total ozone with warmer tropopause and lower stratosphere has been re-established. The colder upper tropospheric temperature which is normally associated with maximum ozone concentration throughout the year elsewhere in the world has also been identified in this study but the relationship gets reversed during southwest monsoon months(June-September) over the domain considered. The moisture available in abundance in the lower troposphere gets precipitated due to the convective instability prevailing in the atmosphere during monsoon season and very little moisture is only available for vertical transport into the upper troposphere atop 500 hPa. The latent heat released by the precipitation processes warms up the middle and upper atmosphere. The warm and dry upper troposphere could be the reason for less depletion of ozone in the upper troposphere during monsoonal months and this is supported by the positive correlation coefficient prevailing in monsoon season between total ozone and upper tropospheric (aloft 300 hPa) temperature. The warmness in middle and upper troposphere which is associated with less depletion and/or production of more ozone in the upper troposphere may perhaps contribute for the higher total ozone during monsoon months than in other seasons over peninsular Indian region. The minimum concentration is observed during January (226 DU) over 6° N and the maximum (283DU) over 18° N during August. Longitudinal variability is less pronounced than the latitudinal variability.

Global total ozone recovery trends derived from five merged ozone datasets

We report on updated trends using different merged zonal mean total ozone datasets from satellite and ground-based observations for the period from 1979 to 2020. This work is an update from the trends reported in Weber et al. (2018) using the same datasets up to 2016. Merged datasets used in this study include NASA MOD v8.7 and NOAA Cohesive Data (COH) v8.6, both based on data from the series of Solar Backscatter UltraViolet (SBUV), SBUV-2, and Ozone Mapping and Profiler Suite (OMPS) satellite instruments (1978–present) as well as the Global Ozone Monitoring Experiment (GOME)-type Total Ozone (GTO-ECV) and GOME-SCIAMACHY-GOME-2 (GSG) merged datasets (both 1995–present), mainly comprising satellite data from GOME, SCIAMACHY, OMI, GOME-2A, -2B, and TROPOMI. The fifth dataset consists of the annual mean zonal mean data from ground-based measurements collected at the World Ozone and UV Radiation Data Center (WOUDC). Trends were determined by applying a multiple linear regression (MLR) to annual mean zonal mean data. The addition of four more years consolidated the fact that total ozone is indeed on slowly recovering in both hemispheres as a result of phasing out ozone depleting substances (ODS) as mandated by the Montreal Protocol. The near global ozone trend of the median of all datasets after 1996 was 0.5 ± 0.2 (2σ) %/decade, which is in absolute numbers roughly a third of the decreasing rate of 1.4 ± 0.6 %/decade from 1978 until 1996. The ratio of decline and increase is nearly identical to that of the EESC (equivalent effective stratospheric chlorine or stratospheric halogen) change rates before and after 1996 which confirms the success of the Montreal Protocol. The observed trends are also in very good agreement with the median of 17 chemistry climate models from CCMI (Chemistry Climate Model Initiative) with current ODS and GHG (greenhouse gas) scenarios. The positive ODS related trends in the NH after 1996 are only obtained with a sufficient number of terms in the MLR accounting properly for dynamical ozone changes (Brewer-Dobson circulation, AO, AAO). A standard MLR (limited to solar, QBO, volcanic, and ENSO) leads to zero trends showing that the small positive ODS related trends have been balanced by negative trend contributions from atmospheric dynamics resulting in nearly constant total ozone levels since 2000.

Universal spectrum for short period (days) variability in atmospheric total ozone

Long-range spatio-temporal correlations manifested as the self-similar fractal geometry to the spatial pattern concomitant with inverse power law form for the power spectrum of temporal fluctuations are ubiquitous to real world dynamical systems and are recently identified as signatures of self-organized criticality Self-organised criticality in atmospheric flows is exhibited as the fractal geometry 10 the global cloud cover pattern and the inverse power law form for the atmospheric eddy energy spectrum, In this paper, a recently developed cell dynamical system model for atmospheric flows is summarized. The model predicts inverse power law form of the statistical normal distribution for atmospheric eddy energy spectrum as a natural consequence of quantum-like mechanics governing atmospheric flows extending up to stratospheric levels and above, Model Predictions are in agreement with continuous periodogram analyses of atmospheric total ozone. Atmospheric total ozone variability (in days) exhibits the temporal signature of self-organized criticality, namely, inverse power law form for the power spectrum. Further, the long-range temporal correlations implicit to self-organized criticality can be quantified in terms of the universal characteristics of the normal distribution. Therefore the total pattern of fluctuations of total ozone over a period of time is predictable.

Unusual high total ozone over New Delhi on 25 March 1990- A case study

An unusual high total ozone value of 373 Dobson unit was observed over New Delhi on 25 March 1990. It is attributed to the leakage of stratospheric ozone into troposphere through tropopause break in association with a trough in mid-tropospheric westerlies with its axis lying along 82° E longitude north of 20° N, at 300 hPa level.

Ozone variation over tropics: Trends revealed from Dobson measurement over Indian stations

. Variations in ozone amounts have been studied using data obtained with Dobson spectrophotometers during 1966-1988 at Srinagar, New Delhi, Pune and Kodaikanal. Yearly average values of total ozone , and its vertical distribution by the Umkehr method in layers 1 to 9 have been computed. Departures from compo- site avarage value for the period (1966-1988) have been computed for both total ozone and its vertical distribution. The variation over New Delhi and Pune have been compared with those at Arosa reported by Dutsch {1989). The observed variations in the ozone distribution at New Delhi and Pune can be explained, as being within normal interannual changes. Tropospheric ozone in layer lover New Delhi shows some effects of an anthropogenic nature, on the other hand Pune does not exhibit in any influence of pollutants in any layer, either in the troposphere or stratosphert.

Total ozone potential vorticity and tropopause pressure : A comparative Analysis over south-east Asia

On the basis of TOMS data, a comparative analysis of total ozone. potential vorticity and tropopause pressure has been done over the area 20°- 50° N, 90° -160° E (south-east Asia) for a period October 1982 to September, 1983. The study has been done for three different latitude bands 20°-30° N, 30°-40° N and 400-50° N. High correlations have been found near the tropopause level at all seasons except in autumn.

Climate changes and trends over India

Based on the instrumental observations of over a century available in India, attempt is made to study if there is a clear-cut evidence of any climate change or trend over .India with particular reference to rainfall, surface temperature, atmospheric pressure and total ozone. The study concludes that while there are year to year random. fluctuations in these atmospheric variables and there are certain epochal increases and decreases in respect of rainfall and .surface temperature, .there appears to be no systematic climate charge or trend over India. There IS also no evidence of ozone depletion over India.

kya jalavaayu parivartan saur badalaav se prabhaavit hota hai?

At present, climate change is a matter of great concern to mankind. This change, which is due to the manmade activities, is changing global temperature and the concentration of CO2 and O3 in the atmosphere. But there are some changes in the sun also. Solar changes could be assessed by solar flux at 10.7cm wavelength. Climate change could be assessed by long time temperature records. In this study we have examined whether solar change has any effect on climate change? We have analyzed two sets of data, 10.7cm solar flux (TSI) and global temperature record, along with total ozone, UV-B flux at ground and satellite data of total solar irradiance. Global temperature anomaly curve (GTAC) shows a slow increase of temperature up to about 1975 and a rapid rise after this year. Solar flux at 10.7cm wavelength shows a decreasing trend up to about 1970 and an increasing trend after this year. It also has 11 year cycle. GTAC, total ozone, UV-flux at ground and TSI also show 11 year cycle and some trend, but none of them matches the long-term trend found in solar flux at 10.7cm wavelength.

Variability and trends in surface solar spectral ultraviolet irradiance in Italy: on the influence of geopotential height and lower-stratospheric ozone

The short- and long-term variability of the surface spectral solar ultraviolet (UV) irradiance is investigated across Italy using high-quality ground-based measurements from three locations: Aosta (45.7∘ N, 7.4∘ E, 570 m a.s.l.), Rome (41.9∘ N, 12.5∘ E, 15 75 m a.s.l.), and Lampedusa (35.5∘ N, 12.6∘ E, 50 m a.s.l.). The three sites are characterized by different environmental conditions and represent almost the full latitudinal extent of the Italian territory. Data of two periods were analysed: 2006–2020 (all sites) and 1996–2020 (Rome only). The main objective of this study is to quantify the effect of the geopotential height (GPH) at 250 hPa on total ozone, and spectral irradiance at 307.5 and 324 nm. We first show that monthly anomalies in GPH, total ozone, and spectral irradiances are correlated amongst the three sites, suggesting that Italy is often affected by the same synoptical weather systems. We further find statistically significant anticorrelations between GPH and monthly anomalies in total ozone for all stations and months. Conversely, we identify positive correlations between GPH and monthly anomalies in spectral irradiance at 307.5 nm for most months. The influence of GPH on short-term variability also hold for long-term trends. For example, long-term changes in total ozone over the period 2006–2020 were associated with changes in GPH for all stations. This suggests that observed negative trends in total ozone were mainly driven by changes in lower-stratospheric ozone as upper-stratospheric ozone was increasing over this period. For several months of the year, positive trends in UV irradiance were observed, and we found that these trends were predominantly caused by changes in clouds and/or aerosols instead of total ozone. For the longer period of 1996–2020, a statistically significant annualized decrease in total ozone of ∼ 0.1 % per year was identified for Rome and could subsequently be attributed to decreasing lower-stratospheric ozone. While positive trends in spectral irradiance at 307.5 nm were observed for several months of this extended period, the negative trend in total ozone did not lead to a positive trend in the spectral irradiance at 307.5 nm in the deseasonalized data. Our study provides evidence that dynamical processes taking place in the troposphere lead to significant variability in total ozone and surface solar UV irradiance.