Total Ozone Amount Research Articles

A note on the comparison between total ozone from Oslo CTM2 and SBUV satellite data

The results of a comparison between total ozone amounts derived from solar backscatter ultraviolet (SBUV) satellite observations and those calculated from the chemical transport model Oslo CTM2 are presented for the period 2001–2007. Monthly mean total ozone amounts from improved model simulations were used to compute monthly, seasonal and annual zonal means over 10° latitude zones, and compared with respective satellite retrievals over the northern and southern hemispheres. The results show that the improved model simulations slightly underestimate total ozone over the northern hemisphere when compared with the satellites by 1.4% on average, and slightly overestimate total ozone over the southern extra-tropics, middle and high latitudes by 1.6% on average. The mean difference between the model- and satellite-derived total ozone columns from 75°S to 75°N is estimated to be about −0.3%. A linear regression analysis between the model- and satellite-derived total ozone data shows statistically significant correlations between the two data sets at all latitude zones (about +0.8 in the tropics and more than +0.9 over all other latitudes). The annual cycle of total ozone is shown to be well reproduced by the model at all latitudes.

Near-Real-Time Ocean Color Data Processing Using Ancillary Data From the Global Forecast System Model

This paper investigates the improvements to the quality of ocean color data using an appropriate choice of ancillary data for National Oceanic and Atmospheric Administration (NOAA) operational ocean color data processing, which requires routine ocean color product production in near real time. The ancillary data, such as the total column ozone amount, sea surface wind speed, atmospheric pressure, and total column water-vapor amount, are required for satellite ocean color data processing for deriving ocean color products, e.g., normalized water-leaving radiance spectra data, chlorophyll-a concentration, water diffuse attenuation coefficient, etc. Currently, NOAA's CoastWatch program uses the climatology ancillary data for the near-real-time ocean color data processing. Alternative ancillary data sets that can replace the climatology data for the near-real-time ocean color data processing have been investigated and studied. The studies were carried out from four selected NOAA CoastWatch regions covering the U.S. coastal and Hawaii regions and for four months (January, April, July, and October), representing the four seasons. Based on the evaluation results, we propose to use the ancillary data produced from the Global Forecast System (GFS) model for the NOAA operational ocean color data processing, as well as for any other near-real-time data processing that requires ancillary data inputs. The effects of using the GFS model data on the accuracy of the derived ocean color products are also investigated and discussed.

Implications of climate change for skin cancer prevention in Australia

It is estimated that nearly 450,000 Australians get skin cancer every year. Ultraviolet (UV) radiation from sunlight has been identified as the cause of more than 95% of skin cancers in Australia. Accordingly, the focus of skin cancer prevention programs is reducing exposure to UV radiation. In Victoria, improvements in sun protection behaviours and reductions in sunburn and melanoma incidence rates among younger people have been observed since the SunSmart program was established in 1988. However, climate change has the potential to undermine these successes. First, surface UVB radiation is dependent on stratospheric total ozone amounts. While signs of impact of international restrictions on the production of ozone-depleting substances have been observed, improvements have not yet returned ozone to pre-1970s levels. Interactions between ozone depletion and climate change may slow the recovery of the ozone layer and compound increases in UV radiation at some latitudes. Before recovery, it is expected that higher levels of UV radiation will continue in most Australian regions, with an associated higher risk of skin cancer. Indeed, recent data show increases in surface UV radiation throughout Australia since the 1970s. Second, mean temperatures in Australia have increased over the past 30 years and are projected to rise further by 2030. Australian data shows that with higher temperatures, adults spend more time outdoors, are less likely to wear covering clothing and more likely to be sunburnt. Hence, rising temperatures can be expected to result in increases in sun exposure, sunburn and correspondingly, skin cancer risk.

Enhancement of Ozone and Carbon Monoxide Associated with Upper Cut-off Low during Springtime in East Asia

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth’s surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth’s surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

The UV index: definition, distribution and factors affecting it.

The UV Index was introduced in Canada in 1992 in response to growing concerns about the potential increase of ultraviolet (UV) radiation due to ozone depletion. The index was adopted as a standard indicator of UV levels by the World Meteorological Organization and World Health Organization in 1994. This survey article gives an overview of the UV Index and the main features of its geographical distribution. UV index values are determined from measurements made by ground-based spectrometers, broad-band filter radiometers and multi-filter radiometers. Radiative transfer models are used to estimate UV Index values from other types of geophysical observations, primarily column ozone and cloud thickness. UV Index values can also be retrieved from satellite measurements of atmospheric ozone and cloud cover. Forecasts of UV Index values are now widely available and are intended to be used by the public as a guide to avoid excessive exposure to UV radiation. Over the US and Canada, mean noontime UV Index values in summer range from 1.5 in the Arctic to 11.5 over southern Texas and can be as high as 20 at high elevations in Hawaii. The UV Index is also often used to quantify UV levels in studies investigating the impact of UV on other biological and photochemical processes. Factors affecting the UV Index, such as the sun elevation, total amount of ozone in the atmosphere, cloud cover, reflection from snow and local pollution, are also discussed. Since its introduction in 1992, the UV Index has become a widely used parameter to characterize solar UV. Information about it can be useful for helping people avoid excessive levels of UV radiation.

The UV Index: Definition, Distribution and Factors Affecting It

The UV Index was introduced in Canada in 1992 in response to growing concerns about the potential increase of ultraviolet (UV) radiation due to ozone depletion. The index was adopted as a standard indicator of UV levels by the World Meteorological Organization and World Health Organization in 1994. This survey article gives an overview of the UV Index and the main features of its geographical distribution. UV index values are determined from measurements made by ground-based spectrometers, broad-band filter radiometers and multi-filter radiometers. Radiative transfer models are used to estimate UV Index values from other types of geophysical observations, primarily column ozone and cloud thickness. UV Index values can also be retrieved from satellite measurements of atmospheric ozone and cloud cover. Forecasts of UV Index values are now widely available and are intended to be used by the public as a guide to avoid excessive exposure to UV radiation. Over the US and Canada, mean noontime UV Index values in summer range from 1.5 in the Arctic to 11.5 over southern Texas and can be as high as 20 at high elevations in Hawaii. The UV Index is also often used to quantify UV levels in studies investigating the impact of UV on other biological and photochemical processes. Factors affecting the UV Index, such as the sun elevation, total amount of ozone in the atmosphere, cloud cover, reflection from snow and local pollution, are also discussed. Since its introduction in 1992, the UV Index has become a widely used parameter to characterize solar UV. Information about it can be useful for helping people avoid excessive levels of UV radiation.

On the Retrieval Errors of Ultraviolet Back-Scattered Radiation Measuring Total Ozone

Now total atmospheric ozone amount derivation from the solar ultraviolet radiation backscattered from Earth measured by satellite has been one of the main methods to obtain total ozone amount data.Based on simulating calculation results,the paper studies and discusses the parameters which would influence the retrieval of total ozone amount arising from instrument errors and academic calculation errors,then quantificationally calculates the retrieval errors of total ozone amount induced by atmospheric radiative transfer model calculation errors,retrieval algorithm errors and instrument errors.The results obtained are very important for the precision improvement of total ozone amount retrieval and are directive for the disposal of the true datum obtained from FY- 3A total ozone unit(FY-3A/TOU) in the future.

Seasonal start of the Antarctic ozone hole derived from observations with Dobson spectrophotometers

The Antarctic ozone hole appears in the Antarctic spring, just after the polar night period when sunlight is not available on the surface. Because it is not possible to have a large solar elevation angle in the Antarctic winter and spring, it is hard to make observations of total ozone amounts with TOMS or Dobson spectrophotometers using sunlight. Because of this there is not enough information about the total ozone amounts over the Antarctic just before and after the seasonal appearance of the Antarctic ozone hole. We have made an analysis of the total ozone amounts with a Dobson spectrophotometer, using moonlight as well as sunlight at the three Antarctic stations and Macquarie Island. The results derived from the analysis are as follows: (1) The decrease of the total ozone amounts leading to the Antarctic ozone hole started at the beginning of August at around 69° south and then took place at the higher latitudes later in the period from 1993 to 2005: (2) The total ozone amounts at the higher latitudes in the Antarctic show the smaller value as a latitudinal gradient of about 1.6 DU per degree in the period from 1993 to 2005. The author hopes that these results will be useful for better understanding of the Antarctic ozone hole.

Measurement of internal stray light within Dobson ozone spectrophotometers

The Dobson ozone spectrophotometer is the primary ground-based instrument making measurements of total column ozone. Knowledge of the ozone layer prior to the satellite measurements is derived from these instruments' more than 80-year record. Internal stray light within the instrument limits its ability to make accurate measurements at high total ozone amounts and high solar zenith angles (SZAs). Additionally, a recent analysis of comparative Dobson observations of the Umkehr effect (an SZA-dependent series of measurements on the clear zenith that are used to produce an ozone vertical profile) has shown that internal stray light produces incompatible results between compared instruments. We present a method of making a measurement of this internal stray light, as well as other approaches to evaluating the approximate level of the internal stray light. These techniques can also be used to improve the results of direct Sun observations at high latitudes and high ozone.

UV radiation and skin cancer in Norway

A distinct increase in skin cancer incidences is observed since the registration started in Norway in the 1950s. As UV radiation is assumed to be the main risk factor for skin cancer, hourly values of the UV irradiance were reconstructed for the period 1957–2005 for 17 of the Norwegian counties (58–70°N). For reconstruction, a radiation transfer model is run with total ozone amount and cloud information as meteorological input. Reconstructed hourly erythemally weighted UV irradiances for about 5 years are compared to measurements at four stations, two stations representing the north–south extension of Norway, and two stations at about 60°N representing the eastern inland – Western coastal contrasts. The agreement between reconstructed and measured UV varies between 0% for the northernmost site to 10–15% overestimation for the other locations. For clear sky, a reasonable agreement between reconstructed and measured data was found for all stations, while for overcast, an overestimation of 10–20% was found for all but the northernmost station. Both the cancer incidences and the reconstructed UV values have a distinct north–south increase. The UV increase towards south is mostly due to increasing solar elevation. The west to east increase is much smaller, and differences in UV are due to differences in both cloud optical thickness and total cloud amount. One additional outcome from this work is that long-term UV-data are reconstructed for Norway, data that can be used in further biological and medical studies related to UV effects.

On least squares estimation for long-memory lattice processes

A flexible class of anisotropic stationary lattice processes with long memory can be defined in terms of a two-way fractional ARIMA (FARIMA) representation. We consider parameter estimation based on minimizing an approximate residual sum of squares. The method can be applied to sampling areas that are not necessarily rectangular. A central limit theorem is derived under general conditions. The method is illustrated by an analysis of satellite data consisting of total column ozone amounts in Europe and the Atlantic respectively.

Evaluation of Atmospheric Infrared Sounder ozone profiles and total ozone retrievals with matched ozonesonde measurements, ECMWF ozone data, and Ozone Monitoring Instrument retrievals

An evaluation of the Atmospheric Infrared Sounder (AIRS) version 4 (V4) and version 5 (V5) retrieved ozone profiles and the total column ozone is performed using collocated ozonesonde (O3SND) profiles and total ozone measurements from the World Ozone and Ultraviolet Radiation Data Center (WOUDC) archives. Using O3SNDs and Brewer/Dobson Network (BD) measurements as the truth, bias and root‐mean‐squared (RMS) difference statistics are computed for the AIRS ozone profile retrievals and the derived total ozone. In addition, global monthly maps of total ozone generated for the AIRS retrievals are compared with the Ozone Monitoring Instrument (OMI) and the Solar Backscatter Ultra Violet (SBUV/2) instrument derived maps to evaluate the characteristic trends and seasonal cycle depicted by the AIRS retrieval. The results of the validation exercise reveal that the AIRS V5 algorithm significantly improves the ozone profile retrieval biases and RMS differences for the lower troposphere and, especially, over the tropical region where the V4 algorithm shows larger discrepancies with the O3SND measurements. The V5 retrieval biases with global O3SNDs are less than 5% for both the stratosphere and the troposphere. The RMS differences are less than 20% for the upper stratosphere and are close to 20% for the lower stratosphere and the troposphere. Total ozone amounts from both the V4 and V5 versions agree well with the global BD station measurements with a bias of less than 4% and an RMS difference of approximately 8%. Analysis of V5 total ozone monthly maps reveals that the V5 ozone retrievals depict seasonal trends and patterns in concurrence with OMI and SBUV/2 observations.

A new technique for retrieval of tropospheric and stratospheric ozone profiles using sky radiance measurements at multiple view angles: Application to a Brewer spectrometer

This paper describes and applies a new technique for retrieving diurnal variability in tropospheric ozone vertical distribution using ground‐based measurements of ultraviolet sky radiances. The measured radiances are obtained by a polarization‐insensitive modified Brewer double spectrometer located at Goddard Space Flight Center, in Greenbelt, Maryland, USA. Results demonstrate that the Brewer angular (0–72° viewing zenith angle) and spectral (303–320 nm) measurements of sky radiance in the solar principal plane provide sufficient information to derive tropospheric ozone diurnal variability. In addition, the Brewer measurements provide stratospheric ozone vertical distributions at least twice per day near sunrise and sunset. Frequent measurements of total column ozone amounts from direct‐sun observations are used as constraints in the retrieval. The vertical ozone profile resolution is shown in terms of averaging kernels to yield at least four points in the troposphere–low stratosphere, including good information in Umkehr layer 0 (0–5 km). The focus of this paper is on the derivation of stratospheric and tropospheric ozone profiles using both simulated and measured radiances. We briefly discuss the necessary modifications of the Brewer spectrometer that were used to eliminate instrumental polarization sensitivity so that accurate sky radiances can be obtained in the presence of strong Rayleigh scattering and aerosols. The results demonstrate that including a site‐specific and time‐dependent aerosol correction, based on Brewer direct‐sun observations of aerosol optical thickness, is critical to minimize the sky radiance residuals as a function of observing angle in the optimal estimation inversion algorithm and improve the accuracy of the retrieved ozone profile.

Solar radiation budget and radiative forcing due to aerosols and clouds

This study integrates global data sets for aerosols, cloud physical properties, and shortwave radiation fluxes with a Monte Carlo Aerosol‐Cloud‐Radiation (MACR) model to estimate both the surface and the top‐of‐atmosphere (TOA) solar radiation budget as well as atmospheric column solar absorption. The study also quantifies the radiative forcing of aerosols and that of clouds. The observational input to MACR includes data from the Multiangle Imaging Spectroradiometer (MISR) for aerosol optical depths, single scattering albedos, and asymmetry factors; satellite retrieved column water vapor amount; the Total Ozone Mapping Spectrometer (TOMS) total ozone amount; and cloud fraction and cloud optical depth from the Cloud and Earth's Radiant Energy System (CERES) cloud data. The present radiation budget estimates account for the diurnal variation in cloud properties. The model was validated against instantaneous, daily and monthly solar fluxes from the ground‐based Baseline Surface Radiation Network (BSRN) network, the Global Energy Balance Archive (GEBA) surface solar flux data, and CERES TOA measurements. The agreement between simulated and observed values are within experimental errors, for all of the cases considered here: instantaneous fluxes and monthly mean fluxes at stations around the world and TOA fluxes and cloud forcing for global annual mean and zonal mean fluxes; in addition the estimated aerosol forcing at TOA also agrees with other observationally derived estimates. Overall, such agreements suggest that global data sets of aerosols and cloud parameters released by recent satellite experiments (MISR, MODIS and CERES) meet the required accuracy to use them as input to simulate the radiative fluxes within instrumental errors. Last, the atmospheric solar absorption derived in this study should be treated as an improved estimate when compared with earlier published studies. The main source of improvement in the present estimate is the use of global distribution of observed parameters for model input such as aerosols and clouds. The agreement between simulated and observed solar fluxes at the surface supports our conclusion that the present estimate is an improvement over previous studies. MACR with the global input data was used to simulate the global and regional solar radiation budget, aerosol radiative forcing and cloud radiative forcing for a 3‐year period from 2000 to 2002. We estimate the planetary albedo for a 3‐year average to be 28.9 ± 1.2% to be compared with CERES estimate of 28.6% and ERBE's estimate of 29.6%. Without clouds (including aerosols) the planetary albedo is only 15.0 ± 0.6%. The global mean TOA shortwave cloud forcing is −47.5 ± 4 W m−2, comparing well with the CERES and ERBE estimates of −46.5 and −48 W m−2, respectively. The clear‐sky atmospheric absorption is 72 ± 3 W m−2, and the surface absorption is 218 ± 4 W m−2. Clouds in all‐sky conditions enhance atmospheric absorption from 72 ± 3 W m−2 to 79 ± 5 W m−2 and decrease surface solar absorption from 218 ± 4 W m−2 to 164 ± 6 W m−2. The present estimate of 79 W m−2 for all‐sky solar absorption is much larger than the Intergovernmental Panel on Climate Change (2001) values of about 67 W m−2. Most of the increased atmospheric solar absorption is due to improved treatment of aerosol absorption (backed by surface based aerosol network and chemical transport models) and water vapor spectroscopic data. The global mean clear‐sky aerosol (both natural and anthropogenic) radiative forcing at the TOA and the surface are −6.0 ± 1 W m−2 and −11.0 ± 2 W m−2, respectively. In the presence of clouds the aerosol radiative forcing is −3.0 ± 1 W m−2 (at TOA) and −7.0 ± 2 W m−2 (at the surface). The study also documents the significant regional variations in the solar radiation budget and radiative forcing of aerosols and clouds.

Relationship of total ozone amount, UV radiation intensity, and the ground-level ozone concentration at rural Lithuanian sites

Relationship of total ozone amount, UV radiation intensity, and the ground-level ozone concentration at rural Lithuanian sites

New methodology applied to deriving total ozone and other atmospheric variables from global irradiance spectra

A new sampling and analysis method for acquiring low‐noise spectra using the Brewer spectrophotometer is applied to ground‐based spectral measurements of global ultraviolet radiation. The new technique substantially reduces noise caused by changing atmospheric conditions that can occur during the sampling period. Routine measurements made at Toronto between 1996 and 2006 were used to develop a statistical model for determining total ozone and other variables from the global spectral data. Long‐term comparison of global measurements with direct measurements demonstrates that global scan data can be used to measure total ozone with an accuracy better than ±1% for a wide variety of total ozone amounts and vertical profiles under clear skies. Other information such as ozone temperature and instrument wavelength stability can also be extracted. The measurements compared with model results show good agreement for clear‐sky conditions. The results indicate that atmospheric aerosols and clouds can enhance absorption of UV radiation by ozone. For aerosol optical depth of one, the absorption enhancement is about 2.0% at air mass value of 1 and drops to 0.5% enhancement for air mass values between 2 and 3. For clouds the enhancement is generally small in winter months but can be substantial in summer months. The statistical relationship used for measuring total ozone using spectral global irradiance data is given. Comparisons of total ozone and ozone temperature derived from global scans with those from direct Sun scans are shown, and the effects of aerosols and clouds on derived total ozone from global data are discussed.

Cooling trend in the upper troposphere and lower stratosphere over China

A strong cooling trend (−0.62°C per decade) in the upper troposphere and lower stratosphere (UTLS) over China is detected based on the records of 109 radiosonde stations during the period from 1980 to 2004. In contrast, the underlying mid and lower troposphere (MLT) exhibits a relatively weak warming trend (0.17°C per decade) with the largest magnitude at the surface. Accompanying these changes in air temperature, large‐scale circulation associated with the monsoon activity in East Asia declines remarkably in both winter and summer. Meanwhile, decreasing trend of the total ozone amount has also been found in the same period. Numerical simulations using two global coupled climate models further suggest that the ozone depletion and enhanced anthropogenic greenhouse effect play an important role in the cooling of UTLS and warming of MLT.

Empirical model for estimating daily erythemal UV radiation in the Central European region

Because of its biological effects, erythemal ultraviolet (UV-ERY) radiation (280-400 nm) is a significant part of solar radiation spectrum. In this study a statistical model for estimating daily UV-ERY radiation values was developed. It is based on ground measurements conducted at eight Austrian stations (from 2000 to 2002). As inputs the model requires daily global radiation, daily extraterrestrial radiation, information about the column of total ozone in the atmosphere and the altitude of a selected station. Subsequently the performance of the model was verified by an independent data set originating from measurements in Austria and Czech Republic stations. The verification showed satisfactory performance of the model: the coefficient of determination (R 2 ) varied from 0.97 to 0.99, the root mean square error (RMSE) varied from 9.3 % to 17.7 % and the mean bias error (MBE) varied from -2.5 % to 2.0 %. In addition, the results of the model at Hradec Kralove station were compared with equivalent UV-ERY data from the Solar Radiation Database (SoDa), which are available on the Internet. After successful verification, the model was implemented within the ArcInfo GIS framework in order to carry out a spatial assessment of a stratospheric ozone reduction episode. The event of July 2005 in the Czech Republic was used as a case study. On 30 July 2005 the total ozone amount dropped 12.5 % below the long-term mean, which led to UV-ERY radiation increment ranging from 214 to 391 J·m -2 ·day -1 .

Simplified Calibration for Broadband Solar Ultraviolet Radiation Measurements¶

Aspects of different calibration procedures for erythemally weighing broadband radiometers are presented in this study. These instruments are common in projects dealing with ultraviolet radiation effects on humans. Many erythemally weighing broadband radiometers are still operated using a single calibration factor (cf) that is provided with the instrument. The individual characteristics of every instrument are strongly dependent on the total ozone amount and the solar elevation. Therefore, a calibration procedure also has to take into account the ozone concentrations and the solar elevation to compensate for the effects of the individual characteristics and to provide comparable measurements. Given the variation of the ozone concentrations and the solar elevation, an individual cf has to be calculated for every measurement. Using a simplified version of the calibration procedure, which is presented in this study, can lessen this effort. Taking into account the relevant meteorological conditions for a measuring site, a single cf is calculated to compensate the individual characteristics of the instruments and therefore deliver comparable measurements with less effort.

Ozone mini‐hole over southwestern Spain during January 2004: Influence over ultraviolet radiation

During the last decades, extremely low total ozone events of small spatial extension, named ozone mini‐hole, have been reported in the Northern Hemisphere. A few ozone mini‐hole episodes, which last only few days, were observed over southwestern Spain during 2004. In this work, these extreme events have been detected using TOMS satellite instrument. Additionally, the UV solar radiation was measured in three cities: Badajoz, Cáceres, and Plasencia. The most intensive episode occurred on 10 January 2004 when total ozone amount values decreased to 189–200 DU. These values represent a decrease greater than 33% with respect to the mean values registered in these cities during 1996–2005. In this paper, firstly we analyse the origin of the ozone mini‐hole episode which is related to two atmospheric dynamics processes. Secondly, the influence of these extreme events on ultraviolet radiation recorded under cloud‐free conditions in southwestern Spain is described. A great increase in UV erythemal radiation measurement was recorded on 10 January 2004, between 43% and 75% with respect to values measured on 10 January 2003 and 10 January 2005.