ABSTRACT Ground-based remote measurements of stratospheric trace species began in Lauder, New Zea... more ABSTRACT Ground-based remote measurements of stratospheric trace species began in Lauder, New Zealand (45 S), in December 1980, and have been made continuously since that time. Initially, only NO2 and O3 were measured, using UV/visible scattered light spectroscopy. A variety of other techniques and species have been added since that time, so that today, ongoing, long-term data series exist for HCl, ClONO2, CO, BrO, H2O, spectral UV irradiances, aerosol, and many other trace species. Balloon-borne ozonesondes have been flown regularly since August 1986. We have measured many of the same species at Arrival Heights, Antarctica (78 S), commencing at different times during the period 1982 to 1998. In addition, a variety of long-term measurements are made at these sites in collaboration with overseas investigators, including ClO, O3, and H2O profiles. The principal institution responsible for measurements at the Lauder and Arrival Heights sites is the New Zealand National Institute for Water and Atmospheric Research (NIWA). This presentation will examine some of the principal results from the NIWA data sets, including the long-term trends and variability of the O3 profile, NO2, Cly, and erythemal UV. We will interpret them in relation to anthropogenic emissions and natural events, and in particular address the question whether reversals are detected in the long-term trends in response to emission controls.
ABSTRACT Daily NO2 column measurements have been made at Lauder, New Zealand (45S, 170E) since 19... more ABSTRACT Daily NO2 column measurements have been made at Lauder, New Zealand (45S, 170E) since 1980. The measurement technique utilizes the highly structured absorptions by NO2 which are present in sunlight scattered from the zenith sky at twilight (dawn and dusk). The site is well suited to stratospheric observations because of the very clear troposphere and negligible amounts of NO2 in the boundary layer. The importance of nitrogen oxides, in particular the so called NOx species (NO and NO2), in determining stratospheric ozone concentrations has long been recognized. The NOx species catalytically destroy ozone but in the anthropogenically perturbed lower stratosphere, they can inhibit ozone depletion by converting active halogen and hydrogen compounds into their unreactive reservoirs (e.g. ClONO2 and HNO3). The dominant variation in the measured NO2 values at Lauder is the photochemically induced diurnal and annual cycles, with the El Chichon and Pinatubo volcanic eruptions producing significant episodic reductions. Longer-term patterns have also been identified which suggest that NO2 variation may be predicted by major atmospheric cycles: the solar cycle, quasi-biennial oscillation and southern oscillation index. Based on the current estimates of the influence of these atmospheric cycles and volcanic eruptions, the secular trend in the measurements is estimated to be 5% per decade. Convergence of the trend only occurs after a relatively long period of measurement (>15 years). A range of different models have been used to help elucidate aspects of the observed changes in NO2 over Lauder. Results from these studies will be summarized.
In Lauder, Central Otago, New Zealand, two all-sky imaging systems have been in operation for mor... more In Lauder, Central Otago, New Zealand, two all-sky imaging systems have been in operation for more than 1 yr, measuring the total, opaque, and thin cloud fraction, as well as indicating whether the sun is obscured by clouds. The data provide a basis for investigating the ...
... Karin; Johnston, Paul; Hay, Timothy; Liley, Ben; Thomas, Alan; Martinez-Aviles, Monica; Fries... more ... Karin; Johnston, Paul; Hay, Timothy; Liley, Ben; Thomas, Alan; Martinez-Aviles, Monica; Friess, Udo; Bodeker, Greg; Schofield, Robyn; van ... retrieval algorithm has been developed including a forward model capable of dealing with multiple scattering (Monte Carlo radiative ...
ABSTRACT The column-averaged, dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively)... more ABSTRACT The column-averaged, dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively) were retrieved from short-wavelength infrared (SWIR) spectra observed by the Greenhouse gases Observing SATellite (GOSAT). Continuous measurements of SWIR spectra have been made via GOSAT since 2009, but there has been insufficient investigation of the effects of cirrus clouds and aerosols on the observations. In this work, we investigated the influences of aerosols and cirrus clouds on the differences between GOSAT observations and Total Carbon Column Observing Network (TCCON) data for XCO2 and XCH4 (ΔXCO2 and ΔXCH4) at three sites: Tsukuba and Saga in Japan, and Lauder in New Zealand. We used aerosol optical thickness (AOT), Angstrom exponents (AEs), and single scattering albedo (SSA), all obtained from sky radiometer observations, as well as vertical profiles of aerosols and thin cirrus clouds from lidar observations. Matchups were performed within ±0.1° latitude/longitude rectangular areas of each TCCON site, and within 30 min of the GOSAT overpass time. The results show a negative slope between ΔXCO2 and AOT at 500 nm determined from sky radiometer data at Tsukuba and Saga. The GOSAT XCO2 values tended to be lowered in the presence of cirrus clouds and dense boundary-layer aerosols. Moreover, a significant negative ΔXCO2 was observed at times of large AOTs that resulted from dust-like events. At Lauder, ΔXCO2 was negatively correlated with the AOT at 500 nm, although the AOT at this site was generally small. The mean ± standard deviation for ΔXCO2 and ΔXCH4 at Lauder are −0.80 ± 1.83 (ppm) and −5.27 ± 10.79 (ppb) with correlation coefficients r between GOSAT and TCCON of 0.94 and 0.83, respectively. Both ΔXCO2 and ΔXCH4 were significantly and negatively correlated with the AOT during Sep-Oct-Nov. In addition, stratospheric aerosols caused large negative biases of ΔXCO2 and ΔXCH4 at Lauder despite the small stratospheric aerosol optical depth at that site.
We investigate long term changes in peak erythemally weighted UV (UVI), and in monthly doses of U... more We investigate long term changes in peak erythemally weighted UV (UVI), and in monthly doses of UV-B (280-315 nm) and UV-A (315-400 nm) from spectral irradiance measurements at Lauder, Central Otago. Complementary data sets are used to identify causes of changes. These causes include changes in (a) sun el evation angle, (b) ozone, (c) cloud and aerosol transmissio n, and (d) possible changes in calibration.
In this paper, we compare model calculations of ozone profiles and their variability for the peri... more In this paper, we compare model calculations of ozone profiles and their variability for the period 1998 to 2016 with satellite and lidar profiles at five ground-based stations. Under the investigation is the temporal impact of the stratospheric halogen reduction (chemical processes) and increase in greenhouse gases (i.e., global warming) on stratospheric ozone changes. Attention is given to the effect of greenhouse gases on ultraviolet-B radiation at ground level. Our chemistry transport and chemistry climate models (Oslo CTM3 and EMAC CCM) indicate that (a) the effect of halogen reduction is maximized in ozone recovery at 1–7 hPa and observed at all lidar stations; and (b) significant impact of greenhouse gases on stratospheric ozone recovery is predicted after the year 2050. Our study indicates that solar ultraviolet-B irradiance that produces DNA damage would increase after the year 2050 by +1.3% per decade. Such change in the model is driven by a significant decrease in cloud c...
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 14, 2018
The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform t... more The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood. Some regions will likely receive enhanced levels of UV radiation, while other areas will likely experience a reduction in UV radiation as ozone- and climate-driven c...
ABSTRACT Ground-based remote measurements of stratospheric trace species began in Lauder, New Zea... more ABSTRACT Ground-based remote measurements of stratospheric trace species began in Lauder, New Zealand (45 S), in December 1980, and have been made continuously since that time. Initially, only NO2 and O3 were measured, using UV/visible scattered light spectroscopy. A variety of other techniques and species have been added since that time, so that today, ongoing, long-term data series exist for HCl, ClONO2, CO, BrO, H2O, spectral UV irradiances, aerosol, and many other trace species. Balloon-borne ozonesondes have been flown regularly since August 1986. We have measured many of the same species at Arrival Heights, Antarctica (78 S), commencing at different times during the period 1982 to 1998. In addition, a variety of long-term measurements are made at these sites in collaboration with overseas investigators, including ClO, O3, and H2O profiles. The principal institution responsible for measurements at the Lauder and Arrival Heights sites is the New Zealand National Institute for Water and Atmospheric Research (NIWA). This presentation will examine some of the principal results from the NIWA data sets, including the long-term trends and variability of the O3 profile, NO2, Cly, and erythemal UV. We will interpret them in relation to anthropogenic emissions and natural events, and in particular address the question whether reversals are detected in the long-term trends in response to emission controls.
ABSTRACT Daily NO2 column measurements have been made at Lauder, New Zealand (45S, 170E) since 19... more ABSTRACT Daily NO2 column measurements have been made at Lauder, New Zealand (45S, 170E) since 1980. The measurement technique utilizes the highly structured absorptions by NO2 which are present in sunlight scattered from the zenith sky at twilight (dawn and dusk). The site is well suited to stratospheric observations because of the very clear troposphere and negligible amounts of NO2 in the boundary layer. The importance of nitrogen oxides, in particular the so called NOx species (NO and NO2), in determining stratospheric ozone concentrations has long been recognized. The NOx species catalytically destroy ozone but in the anthropogenically perturbed lower stratosphere, they can inhibit ozone depletion by converting active halogen and hydrogen compounds into their unreactive reservoirs (e.g. ClONO2 and HNO3). The dominant variation in the measured NO2 values at Lauder is the photochemically induced diurnal and annual cycles, with the El Chichon and Pinatubo volcanic eruptions producing significant episodic reductions. Longer-term patterns have also been identified which suggest that NO2 variation may be predicted by major atmospheric cycles: the solar cycle, quasi-biennial oscillation and southern oscillation index. Based on the current estimates of the influence of these atmospheric cycles and volcanic eruptions, the secular trend in the measurements is estimated to be 5% per decade. Convergence of the trend only occurs after a relatively long period of measurement (>15 years). A range of different models have been used to help elucidate aspects of the observed changes in NO2 over Lauder. Results from these studies will be summarized.
In Lauder, Central Otago, New Zealand, two all-sky imaging systems have been in operation for mor... more In Lauder, Central Otago, New Zealand, two all-sky imaging systems have been in operation for more than 1 yr, measuring the total, opaque, and thin cloud fraction, as well as indicating whether the sun is obscured by clouds. The data provide a basis for investigating the ...
... Karin; Johnston, Paul; Hay, Timothy; Liley, Ben; Thomas, Alan; Martinez-Aviles, Monica; Fries... more ... Karin; Johnston, Paul; Hay, Timothy; Liley, Ben; Thomas, Alan; Martinez-Aviles, Monica; Friess, Udo; Bodeker, Greg; Schofield, Robyn; van ... retrieval algorithm has been developed including a forward model capable of dealing with multiple scattering (Monte Carlo radiative ...
ABSTRACT The column-averaged, dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively)... more ABSTRACT The column-averaged, dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively) were retrieved from short-wavelength infrared (SWIR) spectra observed by the Greenhouse gases Observing SATellite (GOSAT). Continuous measurements of SWIR spectra have been made via GOSAT since 2009, but there has been insufficient investigation of the effects of cirrus clouds and aerosols on the observations. In this work, we investigated the influences of aerosols and cirrus clouds on the differences between GOSAT observations and Total Carbon Column Observing Network (TCCON) data for XCO2 and XCH4 (ΔXCO2 and ΔXCH4) at three sites: Tsukuba and Saga in Japan, and Lauder in New Zealand. We used aerosol optical thickness (AOT), Angstrom exponents (AEs), and single scattering albedo (SSA), all obtained from sky radiometer observations, as well as vertical profiles of aerosols and thin cirrus clouds from lidar observations. Matchups were performed within ±0.1° latitude/longitude rectangular areas of each TCCON site, and within 30 min of the GOSAT overpass time. The results show a negative slope between ΔXCO2 and AOT at 500 nm determined from sky radiometer data at Tsukuba and Saga. The GOSAT XCO2 values tended to be lowered in the presence of cirrus clouds and dense boundary-layer aerosols. Moreover, a significant negative ΔXCO2 was observed at times of large AOTs that resulted from dust-like events. At Lauder, ΔXCO2 was negatively correlated with the AOT at 500 nm, although the AOT at this site was generally small. The mean ± standard deviation for ΔXCO2 and ΔXCH4 at Lauder are −0.80 ± 1.83 (ppm) and −5.27 ± 10.79 (ppb) with correlation coefficients r between GOSAT and TCCON of 0.94 and 0.83, respectively. Both ΔXCO2 and ΔXCH4 were significantly and negatively correlated with the AOT during Sep-Oct-Nov. In addition, stratospheric aerosols caused large negative biases of ΔXCO2 and ΔXCH4 at Lauder despite the small stratospheric aerosol optical depth at that site.
We investigate long term changes in peak erythemally weighted UV (UVI), and in monthly doses of U... more We investigate long term changes in peak erythemally weighted UV (UVI), and in monthly doses of UV-B (280-315 nm) and UV-A (315-400 nm) from spectral irradiance measurements at Lauder, Central Otago. Complementary data sets are used to identify causes of changes. These causes include changes in (a) sun el evation angle, (b) ozone, (c) cloud and aerosol transmissio n, and (d) possible changes in calibration.
In this paper, we compare model calculations of ozone profiles and their variability for the peri... more In this paper, we compare model calculations of ozone profiles and their variability for the period 1998 to 2016 with satellite and lidar profiles at five ground-based stations. Under the investigation is the temporal impact of the stratospheric halogen reduction (chemical processes) and increase in greenhouse gases (i.e., global warming) on stratospheric ozone changes. Attention is given to the effect of greenhouse gases on ultraviolet-B radiation at ground level. Our chemistry transport and chemistry climate models (Oslo CTM3 and EMAC CCM) indicate that (a) the effect of halogen reduction is maximized in ozone recovery at 1–7 hPa and observed at all lidar stations; and (b) significant impact of greenhouse gases on stratospheric ozone recovery is predicted after the year 2050. Our study indicates that solar ultraviolet-B irradiance that produces DNA damage would increase after the year 2050 by +1.3% per decade. Such change in the model is driven by a significant decrease in cloud c...
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 14, 2018
The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform t... more The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood. Some regions will likely receive enhanced levels of UV radiation, while other areas will likely experience a reduction in UV radiation as ozone- and climate-driven c...
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