Evidence of the Pinatubo volcanic eruption on the distribution of ozone over the tropical Indian region (original) (raw)
Related papers
Further studies on possible volcanic signal to the ozone layer
Journal of Geophysical Research, 1994
This paper provides a new look at the spatial and temporal distribution of monthly mean residuals of the global ozone field following the two large volcanic eruptions of El Chichon and Pinatubo. The residuals have been calculated after careful removal of the components of known oscillations from the monthly mean total ozone records. The removal eliminated not only the well-established Quasi Biennial Oscillation but also the robust pattern of all El Nino/Southern Oscillation events active during the period of study. These residuals are composed by a "climatic noise" term plus a possible volcanic signal whose amplitude is in some agreement with model calculations particularly over low and middle latitudes following the recent Pinatubo eruption. However, this analysis shows no ozone deficiency following El Chichon over the southern hemisphere and this result can be explained by the prevailing winds in the lower stratosphere in the post-El Chichon period as described in the text. Quantitatively speaking, the magnitude of the observed ozone deficiency which can be attributed to the volcanic effect is smaller than reported earlier either from theory or observations, and ranges between 2 and 4 % at the equatorial latitudes up to about 5% over the middle and high latitudes, including the noise term, and lasting for a period of months after the eruption. These deficiencies are also larger than the anticipated error caused by the aerosol-contaminated radiances, as reported by other scientists. The present results, although not precluding a transient volcanic component following large volcanic eruptions in the ozone records, do show, however, that our understanding of the physical mechanisms involved is probably still incomplete.
Atmospheric Chemistry and Physics, 2009
The eruption of Mount Pinatubo produced the largest loading of stratospheric sulphate aerosol in the twentieth century. This heated the tropical lower stratosphere, affecting stratospheric circulation, and provided enhanced surface area for heterogeneous chemistry. These factors combined to produce record low values of "global" total ozone column. Though well studied, there remains some uncertainty about the attribution of this low ozone, with contributions from both chemical and dynamical effects. We take a complementary approach to previous studies, nudging the potential temperature and horizontal winds in the new UKCA chemistry climate model to reproduce the atmospheric response and assess the impact on global total ozone. We then combine model runs and observations to distinguish between chemical and dynamical effects. To estimate the effects of increased heterogeneous chemistry on ozone we compare runs with volcanically enhanced and background surface aerosol density. The modelled depletion of global ozone peaks at about 7 DU in early 1993, in good agreement with values obtained from observations. We subtract the modelled aerosol induced ozone loss from the observed ozone record and attribute the remaining variability to 'dynamical' effects. The remaining variability is dominated by the QBO. We also examine tropical and mid-latitude ozone, diagnosing contributions from El Niño in the tropics and identifying dynamically driven low ozone in northern mid-latitudes, which we interpret as possible evidence of changes in the QBO. We conclude that, on a global scale, the record lows of extra-polar ozone are produced by the increased heterogeneous chemistry, although there is evidence for dynamics produced low ozone in certain regions, including northern mid-latitudes.
Recent Volcanic Signals in the Ozone Layer
The Mount Pinatubo Eruption, 1996
The eruptions of the low latitude volcanoes EI Chich6n and Pinatubo have disturbed conditions in the stratosphere and the total ozone field. The spatial and temporal distribution of these disturbances is studied using monthly mean total ozone residuals after careful removal of the components of known oscillations (seasonal variation, QBO, EI Nino/Southern Oscillation). The total ozone deficiencies attributed to the volcanic effect are found to range from-2% in the tropical region up to about-5% over middle and high latitudes, lasting for 6 or more months after the eruption. These deficiencies are larger than both the noise term and the anticipated error from the aerosol contaminated radiances.
A CORRELATION STUDY BETWEEN OZONE AND VOLCANIC ACTIVITY
A cross-correlation study for time-lags of -t-5 yrs between eleven ground based ozone stations for ~ = 40°N-75 ° N and ), = 30 o E-114 ° W and five volcanic emissivity indices has shown their close connection: significant correlations well above 90% were obtained. Intepretation of these positive/negative correlations (r) was based on the global wind circulation (aided also by a 2-D, 3-D representation between ~p, A, r), and the types of volcanic aerosols leading to heterogeneous chemical reactions with ozone.
Past changes in the vertical distribution of ozone – Part 3: Analysis and interpretation of trends
Atmospheric Chemistry and Physics Discussions, 2015
Trends in the vertical distribution of ozone are reported and compared for a number of new and recently revised datasets. The amount of ozone-depleting compounds in the stratosphere (as measured by Equivalent Effective Stratospheric Chlorine -EESC) maximised in the second half of the 1990s. We therefore examine the trends in the 5 periods before and after that peak to see if any change in trend is discernible in the ozone record. Prior to 1998, trends in the upper stratosphere (∼ 45 km, 4 hPa) are found to be −5 to −10 % per decade at mid-latitudes and closer to −5 % per decade in the tropics. No trends are found in the mid-stratosphere (28 km, 30 hPa). Negative trends are seen in the lower stratosphere at mid-latitudes in both hemispheres and in 10 the deep tropics. However it is hard to be categorical about the trends in the lower stratosphere for three reasons: (i) there are fewer measurements, (ii) the data quality is poorer, and (iii) the measurements in the 1990s are perturbed by aerosols from the Mt. Pinatubo eruption in 1991. These findings are similar to those reported previously even though the measurements for the two main satellite instruments (SBUV and SAGE II) 15 and the ground-based Umkehr and ozonesonde stations have been revised.
Atmospheric Environment, 2003
Measurements of surface ozone, CO, CH 4 and oxides of nitrogen have been made at a high altitude site Mt Abu (24.6 N, 72.7 E, 1680 m asl), India for the period 1993-2000. Diurnal patterns in ozone do not show daytime in situ photochemical buildup at this site throughout the year. On the contrary, lower ozone mixing ratios are observed during the day. Interestingly, diurnal pattern changes significantly after the northeast monsoon period (winter) and shows a unique double hump in spring at this site. Seasonal variation in ozone shows a pronounced maximum (monthly average about 46 ppbv) in the late autumn and winter, unlike many other global sites. Local pollutants are major contributors to the ozone levels during this period, while regional transport plays a role in spring. Lowest ozone mixing ratio (monthly average about 25 ppbv) is observed during southwest monsoon period (summer), when clean marine air from the Arabian Sea and Indian Ocean reaches to this site. The unique meteorology over this region seems to play an important role in seasonal as well as in diurnal variations in ozone. Background and continental ozone levels are estimated to be 33.4713.3 and 48.179 ppbv, respectively, over this region of India. A correlation study between ozone and CO indicates possibility of incomplete photochemical processes over Asia. Annual average mixing ratios of CO, CH 4 and oxides of nitrogen are observed to be about 131.4735.8 ppbv, 1.6370.04 ppmv and 1.571.4 ppbv, respectively.
Long-term changes in tropospheric ozone
Atmospheric Environment, 2006
Tropospheric ozone changes are investigated using a selected network of surface and ozonesonde sites to give a broad geographic picture of long-term variations. The picture of long-term tropospheric ozone changes is a varied one in terms of both the sign and magnitude of trends and in the possible causes for the changes. At mid latitudes of the S.H. three time series of 20 years in length agree in showing increases that are strongest in the austral spring (August-October). Profile measurements show this increase extending through the mid troposphere but not into the highest levels of the troposphere.
Meteorology and Atmospheric Physics, 2002
Umkehr observations taken during the 1957±2000 period at 15 stations located between 19 and 52 N have been reanalyzed using a signi®cantly improved algorithm-99, developed by DeLuisi and Petropavlovskikh et al. (2000a,b). The alg-99 utilizes new latitudinal and seasonally dependent ®rst guess ozone and temperature pro®les, new vector radiative transfer code, complete aerosol corrections, gravimetric corrections, and others. Before reprocessing, all total ozone values as well as the N-values (radiance) readings were thoroughly re-evaluated. For the ®rst time, shifts in the N-values were detected and provisionally corrected. The reevaluated Umkehr data set was validated against satellite and ground based measurements. The retrievals with alg-99 show much closer agreement with the lidar and SAGE than with the alg-92. Although the latitudinal coverage is limited, this Umkehr data set contains $ 44,000 pro®les and represent the longest ($ 40 years) coherent information on the ozone behavior in the stratosphere of the Northern Hemisphere. The 14-months periods following the El-Chichon and the Mt. Pinatubo eruptions were excluded from the analysis. Then the basic climatological characteristics of the vertical ozone distribution in the 44±52 N and more southern locations are described. Some of these characteristics are not well known or impossible to be determined from satellites or single stations. The absolute and relative variability reach their maximum during winter± spring at altitudes below 24 km; the lower stratospheric layers in the middle latitudes contain $ 62% of the total ozone and contribute $ 57% to its total variability. The layer-5 (between $ 24 and 29 km) although containing 20% of the total ozone shows the least¯uctuations, no trend and contributes only $ 11% to the total ozone variability. Meridional cross-sections from 19 to 52 N of the vertical ozone distribution and its variability illustrate the changes, and show poleward-decreasing altitude of the ozone maximum. The deduced trends above 33 km con®rm a strong ozone decline since the mid-1970s of over 5% per decade without signi®cant seasonal differences. In the mid-latitude stations, the decline in the 15±24 km layer is nearly twice as strong in the winter-spring season but much smaller in the summer and fall. The effect of including 1998 and 1999 years with relatively high total ozone data reduces the overall-declining trend. The trends estimated from alg-99 retrievals are statistically not signi®cantly different from those in WMO 1998a; however, they are stronger by about 1% per decade in the lower stratosphere and thus closer to the estimates by sondes. Comparisons of the integrated ozone loss from the Umkehr measurements with the total ozone changes for the same periods at stations with good records show complete concurrence. The altitude and latitude appearances of the long-term geophysical signals like solar (1±2%) and QBO (2±7%) are investigated.
Atmospheric Environment, 1996
This paper sets forth a new approach for describing long-term changes in total ozone by using frequency distributions and analyzing the extreme values. We applied this methodology to the database of column ozone provided by the Total Ozone Mapping Spectrometer aboard Nimbus 7. We examined a geographic region measuring 7.0 ° in latitude by 6.25 ° in longitude in the midwestern United States from 1979 to 1991. On any given spring day, individual ozone measurements in this region show a large variability, where the differences between the local noon maximum and minimum total ozone values sometimes exceed 100 Dobson units. Daily variability in total column ozone was shown to be greater in the spring than in the fall. Based on frequency distribution results, the most probable values for the spring season
Izvestiya Atmospheric and Oceanic Physics
The differences between the values of partial ozone pressure, temperature, and zonal and meridional wind speeds inherent in the westerly and easterly phases of equatorial stratospheric wind at a level of 50 mbar (westerly values minus easterly values) are analyzed depending on altitude and season. The data of ozonesonde observations performed at several stations in North America, Western Europe, and Japan were used. An essential seasonal dependence of the differences in vertical profiles of ozone, temperature, and wind speed is revealed. A certain vertical structure in the differences is found. In particular, some atmospheric layers show the characteristic properties (extremes) in the vertical profiles of the ozone difference. Among these layers are the vicinity of the upper boundary of the tropopause, the vicinity at a height of 15 km, the lower vicinity of the maximum-ozone layer of or this layer itself, and the layer from 25 to 30-km or above this layer. The phenomena revealed depend not only on latitude but on region within a given latitudinal zone as well. Distinctions in temperature and wind speed correlate well with the results of Holton and Tan, Labitzke and Van Loon. The ozone differences for the midlatitudinal and Arctic stratosphere are most commonly negative, whereas positive differences are noted for the troposphere and low-latitudinal stratosphere. Distinctions in ozone content, temperature, and wind speed for the westerly and easterly phases of the quasi-biennial oscillation are usually most significant in winter. However, in other seasons, the differences (primarily the ozone ones) may be significantly greater than the winter ones. Such behavior occurs usually in the troposphere and middle stratosphere within the layer from 20 to 25 km or above 25 km. It is also important that the ozone differences in a given layer may change sign in different seasons. Possible mechanisms of the above distinctions are discussed.