Variability Of Total Column Ozone Research Articles

Multi-year total ozone column variability at three Norwegian sites and the influence of Northern Hemisphere Climatic indices

Total ozone column (TOC) measurements are retrieved from the Ozone Monitoring Instrument (OMI) onboard the NASA Earth Observing System (EOS) Aura satellite at the three Norwegian sites: Oslo (59.9°N 10.7°E, 1 m a.s.l.), Trondheim (63.4°N 10.4°E, 3 m a.s.l.) and Andøya (69.1°N 15.7°E, 32 m a.s.l.). TOC data have been analysed from 2005 to 2021, in order to detect annual and multi-years total ozone variability. The relationship between geopotential height (GPH) at 250 hPa and total ozone column has been evaluated after showing that monthly anomalies in GPH and TOC are correlated amongst the three sites. The influence of the three Northern Hemisphere Tele Connection (TC) indices (North Atlantic Oscillation, Arctic Oscillation and Scandinavia) on TOC variability has been investigated. It is found that Scandinavia index plays a prominent role for the northernmost latitudes of Andøya and Trondheim while North Atlantic Oscillation and Arctic Oscillation indices are weakly correlated (negatively) to TOC and (positively) to GPH at Oslo. The response of TOC variability to the solar activity at the three sites is also explored and it is noticed that in the period of increasing variation of solar activity, significant TOC anomaly events are only observed in Andøya and Trondheim.

Trends and variability of total column ozone in the Third Pole

The Hindu Kush Himalaya and Tien Shan Mountain regions together are called the Third Pole (TP) of Earth, which encompasses ecologically fragile regions of 12 Asian countries. It is the highest mountain chain with the largest reserve of fresh ice mass on the planet outside the northern and southern polar regions. The TP region is experiencing high rate of glacier melting due to climate change for the past few decades, and is a great concern for water security of South Asia. Since changes in ozone concentrations in the atmosphere affect public health, ecosystem dynamics and climate, it is imperative to monitor its temporal evolution in an ecologically sensitive region such as TP. Here, the spatiotemporal characteristics of total column ozone (TCO) in TP and 20 selected cities in and around TP are investigated using a combined long-term data made from the satellite measurements of Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment (GOME)-2B for the period 2005–2020. The spatial trends in TCO over TP are mostly negative in summer and autumn (from −0.2 DU/yr to −0.6 DU/yr), but positive in winter (up to +0.2 DU/yr). Among the selected 20 urban regions, the highest annual trend −0.42 ± 0.3 DU/yr and the lowest −0.01 ± 0.2 DU/yr are estimated in Xining and Chittagong, respectively. Analysis using a multiple regression model reveals that the ozone variability in TP is mostly driven by tropopause height with a contribution of 24.92%, Quasi-Biennial Oscillation (23.42%), aerosols (16.12%) and solar flux (15.34%). Our study suggests that the observed negative trend is mainly associated with human activities and climate change in TP, which would likely to enhance the surface temperature and thus, melting of glaciers in the region.

Response of Total Column Ozone at High Latitudes to Sudden Stratospheric Warmings

The total column ozone (TCO) at northern high latitudes is increased over a course of 1–2 months after a major sudden stratospheric warming as a consequence of enhanced ozone eddy transport and diffusive ozone fluxes. We analyzed ground-based measurements of TCO from Oslo, Andøya and Ny Ålesund from 2000 to 2020. During this time interval, 15 major sudden stratospheric warmings (SSWs) occurred. The observed TCO variations are in a good agreement with those of ECMWF Reanalysis v5 (ERA5), showing that TCO from ERA5 is reliable, even during dynamically active periods. ERA5 has the advantage that it has no data gaps during the polar night. We found that TCO was increased by up to 190 DU after the SSW of February 2010, over one month. The composite analysis of the 15 SSWs provided the result that TCO is increased on average by about 50 DU over one month after the central date of the SSW.

Trends in short-term variability of total column ozone over Europe for the period 1980–2020 from the ground-based observations and ERA5 reanalysis

The aim of this study is to analyse daily fluctuations in total column ozone (TCO3) to look for trends in characteristics of the passage of low/high TCO3 systems across Europe in the period 1980–2020. For each season of the year in the period 1980–2020, the sample of one-day change in TCO3 as the percentage of the mean ozone for two consecutive days is calculated for twelve ground-based stations with long-term and frequent TCO3 observations. For comparison purposes, the corresponding ERA5 reanalysis data are also considered. Using the seasonal samples of one-day TCO3 fluctuation, the following metrics for the ozone changes are calculated: standard deviation, frequency of exceeding two arbitrarily selected thresholds (10% and 20% for the absolute value of one-day TCO3 fluctuation), and extremes (minimum and maximum value). Both ground-based and ERA5 data provide similar mean values for these metrics in the period 1980–2020. Statistically significant trends in the metrics are only calculated for ∼10% and ∼5% of cases using the ground-based and ERA5 data, respectively. There are both negative and positive trends in the stations’ metrics, which make it impossible to find a common direction of changes. Trends in time series averaging the metrics of individual stations indicate a decreasing spread of one-day TCO3 fluctuations in summer seasons using the ground-based data but this is not found in ERA5 data. The increase in intensity and depth of low/high TCO3 areas moving across Europe, expected from global warming, cannot be supported by the present analysis.

Spatial and Temporal Variation of Total Column Ozone over Turkey with MERRA-2

The main aim of this study is to analyse spatial and temporal variation of total column ozone as well as the trend over Turkey with MERRA-2 Reanalysis for the period 1980-2019. First of all, MERRA-2 total column ozone is compared with Brewer Spectrophotometer located in Ankara in this study. As a result, it is found that MERRA-2 total column ozone agrees quite well (R2=0.9781) with that from the Brewer Spectrophotometer. The trend analysis over Turkey indicates statistically significant decreasing trend in the 1980-1999 period, non-significant decreasing trend in the 2000-2009 period and non-significant increasing trend in the 2010-2019 period. The highest annual average total column ozone are found in Istanbul, Canakkale and Samsun cities with the values of 326.3±6.9 DU, 324.0±6.7 DU and 322.2±6.6 DU, respectively. Total column ozone are the highest in spring, followed by winter, and the lowest in summer and autumn seasons over Turkey.

Snow Nitrate Isotopes in Central Antarctica Record the Prolonged Period of Stratospheric Ozone Depletion From ∼1960 to 2000

AbstractInterpretation of NO3− variability recorded in ice cores remains challenging as it can be lost from snow. Here, we present 60‐year records of NO3− and its isotopic composition (δ15N, δ18O, and Δ17O) in snow in central Antarctica, Dome A. In the upper ∼90 cm snowpack, variations in concentration and isotopic composition of NO3− are dominated by photolytic loss, and δ18O and Δ17O of NO3− are associated with the recycling of NOx to NO3− in the condensed phase driven by photolysis. In the deeper snowpack (∼1960–2000), we observe prolonged trends in concentration and isotopic composition of NO3−, which are best explained as enhanced snow NO3− photolysis due to long‐term decreasing total column ozone (TCO). That is, the prolonged period of trends in NO3− and its isotopes in extremely low snow accumulation sites such as Dome A relay information on variations in TCO and consequently surface solar ultraviolet radiation over time.

A New Chemistry-Climate Model GRIMs-CCM: Model Evaluation of Interactive Chemistry-Meteorology Simulations

We describe a new chemistry-climate model, Global/Regional Integrated Model system Chemistry Climate Model (GRIMs-CCM), developed by coupling the chemistry modules of the GEOS-Chem chemical transport model to the GRIMs general circulation model. The GRIMs-CCM is driven by meteorological variables simulated by the GRIMs and uses simulated gas and aerosol concentrations to calculate the radiative transfer equations at each time step. The model is evaluated by comparing ozone and aerosol concentrations with respective observations from the surface networks and the satellite datasets. It is found that the GRIMs-CCM successfully reproduces the observed spatial distributions of annual-mean aerosol optical depth and captures the seasonal and latitudinal variations of total column ozone. The evaluation of simulated aerosols in surface air against the observations reveals that the model reproduces the observed temporal and spatial variations but shows biases in soil dust aerosols. We also estimate the climatic impact of aerosols by conducting two sets of 10-year simulations for the preindustrial and present conditions. The GRIMs-CCM shows the aerosol radiative forcing of − 0.30 W m−2 from the preindustrial to present-day climates, comparable to the values from other climate model intercomparison projects. These results suggest that the GRIMs-CCM is suitable for studying chemistry-climate interactions and their changes over time.

Assessing the influence of intertropical discontinuity on total column ozone variation over West Africa.

The focus of this study is to evaluate the influence of intertropical discontinuity (ITD) on the variation of total column ozone (TCO). Relevant information is supplied on the temporal and spatial variability of TCO along the ITD zone, which is an important factor influencing the earth's atmosphere. Several studies over the years have established the relationship and have influence several atmospheric processes on TCO. However, the relationship between intertropical discontinuity and TCO over West Africa has a gap. This study tends to examine the influence ITD has on TCO variation using the West African region as a case study. The study used wind, ozone, and dewpoint temperature data for the period between 1980 and 2019. To assess the variability and trend over the study region, several statistical methods were used, including Pearson correlation, Mann-Kendall, and linear regression model. The Mann-Kendall test shows an increasing trend throughout the months over the study region. Spatial analysis also revealed that regions north of the ITD have a higher concentration of TCO than the southern region of the ITD between April and September. However, ITD influence was more visible during the wet months of June to August (JJA) as the highest concentration of TCO was observed during this period across all latitude, but more deviation was observed between latitude 10 to 18° N, while the least occurrence is observed when ITD is at its minimum position in the month of December to February (DJF). The ACRV shows that 14° N exhibit the highest variation with a value of 4.84, while the deviation is also at its highest with value of 13.65. The monthly position of ITD for 40years was also analysed to observe the monthly deviation along the ITD region 40years, and the spatial distribution of TCO was analysed from January to December. It is of note that during the cause of this study, low-ozone values of 220DU are not found in the study region. The highest and the lowest value of TCO is 295 DU and 227 DU, respectively, with an average range of 68DU.

Investigating Contributions of Total Column Ozone Variation on Some Meteorological Parameters in Nigeria

The relationship between some meteorological parameters and variation of total column ozone (TCO) concentration in Nigeria is studied from 1998-2012. The results using a descriptive analysis revealed a seasonal ozone variation having the same trend in all the stations during the period of study. High variability of TCO occurred between December and March coinciding with the period of dry season and low variability of TCO was observed in August coinciding with the period of rainy season. The observed trends in all the stations show that the TCO variation in Nigeria is mostly caused by natural occurrences. Calabar and Port Harcourt stations showed a high percent of TCO variability, while Kano and Maiduguri indicated a low percentage of TCO variability. Using Spearman correlation analysis, TCO concentration has a strong negative correlation with temperature in some stations with correlation coefficient (r) (-0.8392, -0.8531, -0.7832, -8881 and -0.7902) for Calabar, Port Harcourt, Makurdi, Lagos and Ilorin respectively. Kano and Maiduguri showed a weak positive correlation coefficient (r) 0.4965 and 0.3776 respectively. Positive correlation observed in Kano and Maiduguri could be as a result of high dehydration of water vapour in these stations due to seasonal harmattan and latitudinal effects. Probably, some of the substances that could deplete ozone such as HCl, aerosol are soluble in water thereby being washed off by rain during wet season leading to maximum TCO concentration during rainy season. Consequently, the observed phenomenon is through transportation of ozone content through the influence of Brewer-Dobson circulation. Again, during wet season, there is the mechanism of low pressure and lower tropopause height phenomenon, therefore, total ozone enhancement. Interestingly, variation in TCO is part of symbolic tools for tropospheric meteorology alteration and this invariably leads to climate change.

Climatological Study of Ozone over Saudi Arabia

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.

Short-term variability of total column ozone from the Dobson spectrophotometer measurements at Belsk, Poland, in the period 23 March 1963–31 December 2019

Total column ozone (TCO) monitoring with the Dobson spectrophotometer no. 84 have been carried out at Belsk (51°50′, 20°47′), Poland, since 23 March 1963. TCO observations were made for various combinations of double wavelength pairs (AD, CD, CC′) and instrument settings (direct Sun, zenith blue, and zenith cloudy). In total, results of 115,736 manual observations were recorded in the period 1963–2019. The following metrics of the intraday TCO variability are examined: standard deviation divided by the mean value and the difference between the daily maximum and minimum divided by the mean value. The mean value, standard deviation, and 5th–95th percentile range for the intraday changes of the metrics are {1.6%, 0.8%, 2.5%} and {4.3%, 2.3%, 7.3%,}, respectively. To examine interday TCO variability, one-day changes of the metrics and the daily mean TCO are analysed. The corresponding statistics for one-day change of TCO are {−0.2%, 6.9%, 22.6%}. The short-term TCO variability changed only slightly (if ever) since the beginning of the ozone observations at Belsk.

Analysis of Long Term Variation of the Total Column and Tropospheric Ozone over the Indian Region

Ozone plays a significant part in regulating climate change and the chemical characteristics of the atmosphere. Changes in atmospheric ozone can be studied in more detail using ground-based and satellite-based instruments. Studies on the long-term global changes in total column ozone have begun more than three-decade ago using satellite data. The main objective of this work is to analyze the Total Column Ozone (TCO) variations, and tropo-spheric ozone variations over different twenty locations in the Indian sub-continent by using Total Ozone Mapping Spectrometer (TOMS) and AURA OMI/MLS data. The long-term analysis of total column ozone is divided into two phases (1979-1994 and 2005-2018), and tropospheric ozone for one phase (2005-2018) in order to detect changes in the ozone trend pattern. The results of linear regression analysis show a declining trend of total column ozone, and an increasing trend of tropospheric ozone over the selected locations. The impact of wind pattern on the variation of ozone has been analyzed by using NCEP reanalysis data, and found that wind patterns played a prominent role in spatial and temporal changes in total and tropospheric ozone distribution over the subcontinent. Latitudinal variation of total column ozone from Nagarcoil to Anantanag has also been studied for the years 1979, 1994, 2005, and 2018, which indicates an increase in ozone concentration with latitude.

Variability of Total Column Ozone with Solar Activity Features at Northern and Eastern Regions of India

A statistical study of Total Column Ozone (TCO) with Different solar activity features (DSAF), viz. sunspot number, solar flare, solar active prominences for a Northern station Shimla (31°10'N, 77°17'E) and an Eastern station Imphal (24°82'N, 93°94'E) of India is presented using 11 years (2004-2016) of data. In this study we have compared the trends in TCO with DSAF annually as well as for seasonal months. Our study shows a negative correlation between TCO and DSAF. A negative correlation suggests that there is decrease in Ozone concentration during the given time period with solar activity.

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

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.

Spectral analysis approach to study the association between total ozone concentration and surface temperature

The present study endeavors to explore the association between total column ozone (TCO) and surface temperature (ST) over Kolkata, India, during September–November through time series approach. A spectral analysis approach is adopted to investigate the existence of any common cycle in TCO and ST time series. The spectra have been computed, and it has been observed that there exist common spectra of period 24 in both the time series explored in daily scale. The existence of common spectra among TOC and ST during the transition period from monsoon to post-monsoon has been interpreted as a proof of the similarity in fluctuation pattern of TCO and ST. Details of the dependence of the variability of TCO on ST have been discussed.

Numerical Modeling of the Influence of Physical and Chemical Factors on the Interannual Variability of Antarctic Ozone

The variability of Antarctic total column ozone in 1980–2018 is considered. The study analyzes trends in Antarctic total column ozone during the study period as well as the physical and chemical processes affecting the seasonal variability of total column ozone. The main attention is paid to the influence of dynamical processes on the stability of the Antarctic polar vortex, to the formation of polar stratospheric clouds, and to the influence of gas-phase and heterogeneous processes on the surface of polar stratospheric clouds and sulfate aerosol. The method of research is the analysis of the results of ground and satellite observations and numerical modeling of physical and chemical processes over the Antarctic using a global chemistry transport model with the dynamical parameters specified from reanalysis data.

Ozone variation during a case of cyclogenesis

The relationship between total column ozone (TCO) and the development of a cyclonic system that occurred in the period from January 18 to January 25, 1981 has been studied using the ERA-Interim reanalysis database. It was found that TCO increases and decreases with the development and weakening of the cyclonic system. Also, a good correlation between TCO and the thickness of the layer was found between 1000-100 hPa and tropopause pressure. The study of daily variations in TCO based on the vertical distribution of the ozone mass mixing ratio (OMR) illustrate that with the beginning of the growth period there is a high decrease of the tropopause height, which was associated to high deepening of the cyclone and was accompanied by a significant vertical increase of OMR in the troposphere and stratosphere. The obvious significant increase of OMR starts at the stratospheric layer and is then transported to the tropospheric layer. The analysis of the time-height variation of the differences of OMR between the average of the domain containing the center of the cyclone at each level and the corresponding monthly average, illustrates that during the days of maximum deepening the positive values of OMR extend downwards to reach the 850 hPa level. The increase in positive values continues to be higher in the upper levels and reaches maximum values between 300-100 hPa and also between the 60-10 hPa layer. The characteristics of these changes of OMR concentrations from layer to layer are predominantly due to dynamical processes. Also, this was attributed to the effect of horizontal advection of ozone from a different neighboring region into the column, and by a vertical exchange of air between the high ozone at the stratosphere and low ozone at troposphere.

Effect of lower stratospheric temperature on total ozone column (TOC) during the ozone depletion and recovery phases

Abstract Using the Solar Back-scatter Ultraviolet merged ozone data during 1980–2016, the recovery of total ozone column (TOC) is examined in 5° wide latitude bands from 65°S to 65°N across the globe. Since the variability of TOC is influenced by various natural and anthropogenic proxies, a multiple linear regression (MLR) is employed to remove the dynamic variability. Among the proxies, lower stratospheric temperature at ~100hPa plays a significant role in the dynamics of the TOC variability. The MLR model has significantly improved after including the lower stratospheric temperature along with other proxies and the standard deviation of the estimated TOC trend has significantly reduced about 35 to 43% in 50°N-65°N and 16 to 20% in 45°S-65°S after using the lower stratospheric temperature during both the depletion (1980–1996) and recovery (1997–2016) phases. Cooling of lower-middle stratospheric temperature are observed during the depletion phase with −0.09 °C to −0.02 °C year−1. However, during the recovery phase, the temperature at the lower stratosphere is warming. Due to weak signals, the estimated warming trends are not statistically significant. The TOC trends are examined by the increasing or decreasing emission of chlorofluorocarbon, indicated by Equivalent Effective Stratospheric Chlorine (EESC) index. During the recovery phase, the EESC varies from 0.82±0.01 to 0.29±0.005 DU year−1 at 45–65°S using the lower stratospheric temperature. In the northern hemisphere, the recovery trends are weak and varied from 0.21±0.004 to 0.25±0.005 DU year−1 and these trends are statistically significant. This study suggests the importance of the lower stratospheric temperature to derive proper trends using the MLR model.

Total Column Ozone, Precipitable Water Content and Aerosol Optical Thickness Over Atigre Village, a Tropical Station: First Observations

In this paper, we report first-time observations of total column ozone (TCO), aerosol optical thickness (AOT) and precipitable water content (PWC) at five different wavelengths using compact, handheld, multichannel sun photometer (Microtops II ozonometer) at Atigre village (16.74°N latitude, 74.37°E longitude, 604 ms altitude above sea level). The three optical filters at wavelengths 305 nm, 312 nm and 320 nm are used to detect the TCO, while two optical filters 936 nm and 1020 nm are used to detect the PWC and AOT, respectively. We have been collecting data from September 1, 2017, and 122 days are selected from September 1, 2017, to December 31, 2017, to present as first observations of TCO, AOD and PWC. The mean values of TCO, AOT and PWC are found to be 261.2 (± 9.22) DU, 0.25 (± 0.04) and 1.98 (± 0.79) cm, respectively, during this period. The TCO measurements taken by the Microtops II ozonometer are compared with the ozone monitoring instrument satellite data over Atigre. We found that PWC and AOT values are negatively correlated (− 0.54) during monsoon season, while they show positive correlation (0.63) during other seasons with 90% significance level. The diurnal variation of TCO, PWC and AOT differ in monsoon and the post-monsoon season.

Broadband dependence of atmospheric transmissions in the UV and total solar radiation

Atmospheric broadband transmissions of clouds, aerosols, and ozone in the erythemally weighted ultraviolet (EUV, 290–320 nm), total (spectrally integrated) ultraviolet (TUV, 290–363 nm), and total global solar (GS, 305–2800 nm) spectral regions were analysed with ground-based measurements in Seoul, Korea (37.57°N, 128.98°E) from March 2004 to February 2013. The annual average total transmission expressed as a fraction of the clear-sky irradiance was 77.6% in the EUV, 73.6% in the TUV, and 72.0% in the GS spectral regions. The corresponding values for cloud transmission were 78.4%, 73.9%, and 71.7%. In overcast cloudy conditions, atmospheric transmission was reduced by 45.9%, 50.2%, and 56.6% in the three spectral regions, respectively, indicating the dominant effect of clouds. Aerosol and ozone transmissions had almost the same annual average. Annual average atmospheric transmission effectively decreases with increasing wavelength from EUV to GS regions. However, we found that there was a difference in wavelength dependence of atmospheric transmission for monthly averages, which seems related to the monthly variation of total column ozone (TCO), aerosol, and cloud amount. It is also found that there is a critical value of TCO (TCO =370 DU) for the wavelength dependence of transmission. Higher ozone amount than this turnaround value can cause an increase in transmission from the EUV to GS regions. The monthly wavelength-dependent effects may be attributable more to the different climatological characteristics of the TCO rather than aerosols and clouds.