Andrew Klekociuk

• BSc(Hons) PhD
• Senior Researcher at Australian Antarctic Division

Antarctic landfast sea ice (fast ice) is stationary sea ice that is attached to the coast, grounded icebergs, ice shelves, or other protrusions on the continental shelf. Fast ice forms in narrow (generally up to 200 km wide) bands, and ranges in thickness from centimeters to tens of meters. In most regions, it forms in autumn, persists through the...

This assessment provides a comprehensive update of the effects of changes in stratospheric ozone and other factors (aerosols, surface reflectivity, solar activity, and climate) on the intensity of ultraviolet (UV) radiation at the Earth’s surface. The assessment is performed in the context of the Montreal Protocol on Substances that Deplete the Ozo...

Terrestrial organisms and ecosystems are being exposed to new and rapidly changing combinations of solar UV radiation and other environmental factors because of ongoing changes in stratospheric ozone and climate. In this Quadrennial Assessment, we examine the interactive effects of changes in stratospheric ozone, UV radiation and climate on terrest...

We describe the methods and data sources for investigating the stratospheric ozone and planetary waves in the atmosphere in the framework of research provided by our international team. Selected ground-based and satellite instruments for ozone measurements and related reanalyses are described. Examples of data and analysis tools are shown. The tech...

The monograph summarizes the results of studies on the ozone layer dynamics under the influence of planetary waves conducted over the past 25 years. The descriptions concern the ground-based and satellite ozonometric instruments and the results of the comparison of the total ozone observations in Ukraine and Antarctica; characteristics of planetary...

The monograph summarizes the results of studies of the ozone layer dynamics under the infl uence of planetary waves conducted over the past 25 years. The descriptions concern the terrestrial and satellite ozonometric instruments and the results of comparison of the total ozone observations in Ukraine and Antarctica; characteristics of planetary wav...

We examine the zonal wavenumber spectrum of planetary (Rossby) waves in the atmosphere above Antarctica in each of two contrasting years: in 2019, when there was a sudden stratospheric warming (SSW), and in 2020 when the Antarctic stratospheric vortex was unusually strong and long-lived. The ozone hole (OH) is developed over Antarctica in spring, a...

Twenty six years of medium frequency (MF) radar wind measurements made from 1994 to 2019 at Davis Station (68.6°S, 77.9°E) are used to study the mean response of the mesosphere‐lower thermosphere to stratospheric warmings in the Southern Hemisphere. Warming events were detected using Modern‐Era Retrospective Analysis for Research and Applications (...

In the paper the seasonal trends in the zonal asymmetry in the quasi-stationary wave pattern of total ozone column (TOC) at southern polar latitudes have been investigated. We evaluated and compared seasonal trends in the zonal TOC asymmetry from modern era satellite measurements using the Total Ozone Mapping Spectrometer data and the second Chemis...

The 11-year solar activity cycle in the vertical ozone distribution over the Antarctic station Faraday/Vernadsky in the Antarctic Peninsula region (65.25° S, 64.27° W) was analyzed using the Solar Backscatter Ultra Violet (SBUV) radiometer data Version 8.6 Merged Ozone Data Sets (MOD) over the 40-year period 1979-2018. The SBUV MOD ozone profiles a...

Zonal average monthly Solar Backscatter Ultraviolet Radiometer (SBUV) satellite data have been used to study the vertical ozone distribution in 1979–2018. The quasi-11-year period solar activity cycle from the ozone data series was investigated with the wavelet transform. Solar activity was characterized by sunspot numbers and F10.7 solar radio flu...

Monthly mean data from the MERRA-2 reanalysis and CMIP6 model have been examined for austral spring months (September, October, November) over the 1980–2014 period. Analysis was made for 2D (total ozone column) and 3D (ozone partial pressure) climatological mean (1980-2014) values for the zonal band (0º – 90º S) at pressure levels (1000–0.1 hPa) fo...

The level of quasi-stationary planetary wave (QSW) activity in the Antarctic winter stratosphere provides insights into the likely behavior of the ozone hole in the following spring months. Observation of an anomalously large amplitude of the QSW in winter stratospheric temperatures is an indicator that strong disturbances to the polar vortex are l...

The level of quasi-stationary planetary wave (QSW) activity in the Antarctic winter stratosphere provides insights into the likely behavior of the ozone hole in the following spring months. Observation of an anomalously large amplitude of the QSW in winter stratospheric temperatures is an indicator that strong disturbances to the polar vortex are l...

Hydroxyl radical (OH) plays critical roles within the troposphere, such as determining the lifetime of methane (CH4), yet is challenging to model due to its fast cycling and dependence on a multitude of sources and sinks. As a result, the reasons for variations in OH and the resulting CH4 lifetime (τCH4), both between models and in time, are diffic...

The impact of a major sudden stratospheric warming (SSW) in the Arctic in February 2018 on the midlatitude mesosphere is investigated by performing the microwave radiometer measurements of carbon monoxide (CO) and zonal wind above Kharkiv, Ukraine (50.0∘ N, 36.3∘ E). The mesospheric peculiarities of this SSW event were observed using a recently des...

The description of the data used for analysis, CO movements in stratosphere and mesosphere, and vertical profiles of the MLS temperature anomalies are presented in the Supplement. The Aura MLS CO values have been taken from version 4.2x Aura MLS Level 2 data https://mls.jpl.nasa.gov/data/readers.php). Aura MLS v4.2x data have 37 pressure levels. Th...

The impact of a major sudden stratospheric warming (SSW) in the Arctic in February 2018 on the mid-latitude mesosphere was investigated by performing microwave radiometer measurements of carbon monoxide (CO) and zonal wind above Kharkiv, Ukraine (50.0° N, 36.3° E). The mesospheric peculiarities of this SSW event were observed using recently designe...

The near-surface environment of the Southern Ocean is subject to particular biases in weather and climate simulations, particularly during the summer season, and relatively few analyses of cloud and radiation properties have been reported for the region. Here we provide an analysis of ship-based measurements of downwelling radiation, cloud fraction...

Major mid-winter stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in the Arctic stratosphere. Because SSWs are able to cause significant surface weather anomalies on intra-seasonal timescales, several previous studies have focused on their potential future change, as might be induced by anthropogenic forcings....

Major mid-winter stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in the Arctic stratosphere. Because SSWs are able to cause significant surface weather anomalies on intra-seasonal timescales, several previous studies have focused on their potential future change, as might be induced by anthropogenic forcings....

The asymmetry in the Antarctic total ozone zonal distribution has changed during the last four decades, showing an eastward shift in the zonal ozone minimum of quasi-stationary planetary wave. The satellite data 1979-2016 analyzed by the authors related to changes in the zonal asymmetry of the Antarctic ozone and to their coupling with atmospheric...

Ozone is an important component of the Earth's atmosphere that effectively absorbs dangerous solar UV radiation in 200–320 nm wavelengths. The largest amount of ozone (≈ 90 %) is located in the stratosphere at altitudes 25–30 km in tropical regions and 15–20 km in the polar regions. The amount of ozone in the atmosphere varies throughout the year a...

Major mid-winter stratospheric sudden warmings (SSWs) are the largest instance of wintertime variability in the Arctic stratosphere. Because SSWs are able to cause significant surface weather anomalies on intra-seasonal time scales, several previous studies have focused on their potential future change, as might be induced by anthropogenic forcings...

The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record-large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observati...

The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record-large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observati...

Stratosphere-to-troposphere transport (STT) provides an important natural source of ozone to the upper troposphere, but the characteristics of STT events in the Southern Hemisphere extratropics and their contribution to the regional tropospheric ozone budget remain poorly constrained. Here, we develop a quantitative method to identify STT events fr...

Satellite observations demonstrate Antarctic sea ice extent increased between late-1978 and 2015, with significant spatial and seasonal variability. Late spring retreat off George V Land is a major component of the observed increase, but the paucity of proxy records makes interpretation of trends (and impacts) challenging. Here Earth-system modelli...

We consider 5 years of spectrometer measurements of OH(6–2) and O2(0–1) airglow emission intensities and temperatures made near Adelaide, Australia (35∘ S, 138∘ E), between September 2001 and August 2006 and compare them with measurements of the same parameters from at the same site using an airglow imager, with the intensities of the OH(8–3) and O...

The quasi-stationary pattern of the Antarctic total ozone has changed during the last 4 decades, showing an eastward shift in the zonal ozone minimum. In this work, the association between the longitudinal shift of the zonal ozone minimum and changes in meteorological fields in austral spring (September–November) for 1979–2014 is analyzed using ERA...

Stratosphere-to-troposphere transport (STT) provides an important natural source of ozone to the upper troposphere, but the characteristics of STT events in the southern hemisphere extratropics and their contribution to the regional tropospheric ozone budget remain poorly constrained. Here, we develop a quantitative method to identify STT events fr...

The quasi-stationary pattern of the Antarctic total ozone has changed during the last four decades, demonstrating an eastward shift in the zonal ozone minimum. In this work, the association between the longitudinal shift of the zonal ozone minimum and changes in meteorological fields in austral spring (September–November) for 1979–2014 is analyzed....

This paper presents an overview of work undertaken over a number of Australian Antarctic Science projects, beginning in season 2001/02 with a shallow snow pit. In season 2005/06 this was augmented with a 260 m thermally drilled ice core and a 4.5 m snow pit. A core taken in 2008/09 overlapped the 2005/06 core and pit samples. From 2009/10, short co...

Chemistry–climate models are important tools for addressing interactions of composition and climate in the Earth system. In particular, they are used to assess the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator – ch...

Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer ai...

The DEEPWAVE experiment was designed to quantify gravity wave (GW) dynamics and effects from orographic and other sources to regions of dissipation at high altitudes. The core DEEPWAVE field phase took place from May through July 2014 using a comprehensive suite of airborne and ground-based instruments providing measurements from Earth’s surface to...

Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid-latitudes to high latitudes of the Southern Hemisphere (SH), which over the last few decades have experienced extreme and regionally variable trends in precipita...

We review the 2013 Antarctic ozone hole, making use of various ground-based, in-situ and remotely-sensed ozone measurements, ground-based measurements of ultraviolet radiation and meteorological reanalyses. Based on analysis of 34 years of satellite records spanning 1979-2013 (which excludes 1995), we find that in terms of maximum area, minimum ozo...

Southern hemisphere circulation patterns and associated anomalies for the aus-tral spring 2014 are reviewed, with emphasis given to the Pacific Basin climate indicators and Australian rainfall and temperature patterns. Equatorial sea-surface temperatures in the Pacific warmed through the season, and the South-ern Oscillation just exceeded El Niño t...

Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on...

The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is...

Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid-to high-latitudes of the Southern Hemisphere (SH) which over the last few decades has experienced extreme and regional variable trends in precipitation, ocean ci...

Chemistry climate models are important tools for addressing interactions of composition and climate in the Earth System. In particular, they are used for assessing the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator-...

The Deep Propagating Gravity Wave Experiment (DEEPWAVE) was designed to quantify gravity wave (GW) dynamics and effects from orographic and other sources to regions of dissipation at high altitudes. The core DEEPWAVE field phase took place from May through July 2014 using a comprehensive suite of airborne and ground-based instruments providing meas...

Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on-board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on...

Near‐synchronized in situ , space‐borne (A‐Train) and ground‐based lidar observations are employed to evaluate the boundary‐layer clouds (BLCs) over Tasmania and the adjacent Southern Ocean (SO) simulated by the limited‐area version of Australian Community Climate and Earth System Simulator (ACCESS‐C). Two winter cases featuring BLCs associated wit...

The Antarctic region is a pristine environment with minimal anthropogenic influence. Aerosol measurements in this environment allow the study of natural aerosols and polar atmospheric dynamics. Measurements in this region have been limited primarily to continental and coastal locations where permanent stations exist, with a handful of measurements...

Radiosonde observations made from Davis station, Antarctica (68.6°S, 78.0°4 E) between 2001 and 2012 are used to compile a climatology of lower stratosphere inertial gravity wave characteristics. Wavelet analysis extracts single wave packets from the wind and temperature perturbations. Wavelet parameters, combined with linear gravity wave theory, a...

Aerosol measurements in this pristine Antarctic environment allow the study of natural aerosols and polar atmospheric dynamics. Measurements in this region have been limited primarily to continental and coastal locations where permanent stations exist, with only one other measurement campaign passing through the sea ice region. The MAPS campaign (M...

Significant ozone depletion was observed within the southern polar vortex during spring in the 1980s – early 1990s. Later, a stabilization in total ozone levels and ozone hole area has been observed. atmosphere models predict a consequent recovery of the Antarctic ozone. Nevertheless, identification of the long-term processes is complicated by high...

The contribution of Antarctic aerosol formation to the Southern Hemisphere aerosol load, and consequently their impact on the Earth’s albedo, climate and chemistry, is currently unknown. In the Antarctic region, aerosol measurements have been limited primarily to boundary layer air-masses at spatially sparse coastal and continental research station...

The Australian Bureau of Meteorology maintains a number of long-running Dobson measurement programs, among the few in southern hemisphere mid-latitudes. Data from the Melbourne site (the Melbourne/Airport World Ozone and Ultraviolet Radiation Data Centre (WOUDC) station was originally located at Aspendale, then moved to the city centre, and finally...

The Antarctic region is a pristine environment without any significant anthropogenic influence. Measurements of aerosols in this environment therefore allow the study of natural aerosol properties and formation mechanisms in polar conditions, and also allow insight into polar atmospheric dynamics. Measurements in this region have been limited prima...

[1] The proportion of polar stratospheric clouds due to orographic gravity wave (OGW) forcing is quantified during four Antarctic (2007–2010) and four Arctic (2006/2007 to 2009/2010) winter seasons. OGW‒active days are defined as those days above major polar mountain ranges which have wave‒ice polar stratospheric clouds (PSCs), tropospheric wind co...

Atmospheric, oceanic and sea ice conditions in the southern hemisphere are reviewed for the austral spring of 2012, with emphasis given to the Pacific basin climate indicators and Australian rainfall and temperature patterns. The Pacific basin saw a return to neutral ENSO conditions, with slightly warmer than normal equatorial SSTs just east of the...

We report measurements with the mobile IAP Fe-LIDAR and the AAD MST radar at the Australian Antarctic Station Davis (69°S) between December 2010 and December 2012. The dataset includes more than 2900 hours of LIDAR measurements with a temporal resolution of 2 minutes equally distributed throughout the year and local time. The measurements give a go...

The pristine environment of the Antarctic allows the study of natural aerosol properties and formation mechanisms in polar conditions, with minor anthropogenic influence reaching the remote continent. Studies of aerosols over Antarctic sea ice have not been made, with measurement campaigns being confined primarily to permanent stations on continent...

The Global Atmosphere Watch of WMO includes several stations in Antarctica that keep a close eye on the ozone layer during the ozone hole season. Observations made during the ozone holes from 2003 to 2012 will be compared to each other and interpreted in light of the meteorological conditions. Satellite observations will be used to get a more gener...

During August 2011 stratospheric ozone over much of Southern Australia dropped to very low levels (~265 DU) for over a week above major population centers. The weather during this low ozone period was mostly clear and sunny, resulting in measured solar ultraviolet radiation (UVR) levels up to 40% higher than normal, with UV Index > 3 despite being...

Chemistry-Climate Model Validation phase 2 (CCMVal-2) model simulations are used to analyze Antarctic ozone increases in 2000-2100 during local spring and early summer, both vertically integrated and at several pressure levels in the lower stratosphere. Multi-model median trends of monthly zonal mean total ozone column (TOC), ozone volume mixing ra...

Measurements of a number of atmospheric components will be undertaken over 1 year-old sea ice off East Antarctica as part of the Sea Ice Physics EXperiment (SIPEX II) during September and October 2012. SIPEX II is an integrated and multi-disciplinary study of physical and ecological sea ice processes on small to regional scales which aims to enhanc...

Seasonal trends in the quasi-stationary wave pattern of total column ozone at southern polar latitudes are evaluated from modern era satellite measurements and are compared with results from the second Chemistry-Climate Model Validation (CCMVal-2) assessment.

Two years of VHF radar echo power observations are used to examine the structure and variability of the tropopause at Davis, Antarctica. Co-located radiosonde and ozonesonde launches provide data with which to calculate the thermal (lapse-rate) and chemical tropopauses at Davis. The dynamically-controlled radar tropopause can be used as a definitio...

Chemistry-climate model validation phase 2 (CCMVal-2) model simulations are used to analyze Antarctic ozone recovery rates in 2000-2100 during local spring and early summer, both vertically integrated and at several pressure levels in the lower stratosphere. Multi-model median trends of monthly zonal mean total ozone column (TOC), ozone volume mixi...

Measurements of mesosphere and lower thermosphere (MLT) winds obtained using a 2 MHz radar at Davis (68.6°S, 78.0°E) from 1993 to the present have allowed the compilation of a climatology of planetary wave activity and horizontal momentum fluxes. Concurrent measurements of temperature inferred from Hydroxyl emissions have allowed heat fluxes to be...

Local temperature, wind speed, pressure, and solar wind-imposed influences on the vertical electric field observed at Vostok, Antarctica, are evaluated by multivariate analysis. Local meteorology can influence electric field measurements via local conductivity. The results are used to improve monthly diurnal averages of the electric field attributa...

The 2007 Antarctic ozone hole is reviewed from a variety of perspectives, making use of various Australian data and analyses. The 2007 ozone hole was relatively modest, particularly in comparison to that of 2006, due in part to a disturbance to the polar vortex in early September that led to an influx of ozone-rich air. Ozone depletion was still se...

The Global Atmosphere Watch of WMO includes several stations in Antarctica that keep a close eye on the ozone layer during the ozone hole season. Observations made during the ozone holes from 2003 to 2011 will be compared to each other and interpreted in light of the meteorological conditions. Satellite observations will be used to get a more gener...

Stratospheric preconditions for the annual Antarctic ozone hole are analyzed using the amplitude of quasi-stationary planetary waves in temperature as a predictor of total ozone column behaviour. It is found that the quasi-stationary wave amplitude in August is highly correlated with September–November total ozone over Antarctica with correlation c...

Cosmogenic 10Be measured in polar ice cores has important application in the reconstruction of past solar activity. However, the processes controlling its atmospheric transport and deposition to the ice sheets are not fully understood. Here we use the seasonal changes in 10Be concentrations in a 10 year monthly resolved ice core record from the Law...

The Antarctic ozone hole of 2010 is reviewed from a variety of perspectives, making use of various data and analyses. Based on total column ozone metrics, the 2010 ozone hole was one of the smallest in the past fifteen–twenty years. The main influence on the size of the ozone hole was relatively warm temperatures in the Antarctic lower stratosphere...

Stratospheric preconditions for the annual Antarctic ozone hole are analysed using the amplitude of quasi-stationary planetary waves in temperature as a predictor of total ozone column behaviour. It is found that the quasi-stationary wave amplitude in August is highly correlated with September-November total ozone over Antarctica with correlation c...

Observations of the hydroxyl nightglow emission with a scanning spectrometer at Davis station, Antarctica (68°S, 78°E), have been maintained over each winter season since 1995. Rotational temperatures are derived from the P-branch lines of the OH(6-2) band near λ840 nm and are a layer-weighted proxy for kinetic temperatures near 87 km altitude. The...

Gravity wave activity in the upper stratosphere and lower mesosphere (USLM) is investigated using temperature data retrieved from a Rayleigh lidar at Davis, Antarctica (69°S, 78°E) during the 2007 and 2008 winters. The temporal and height variabilities of waves with ground-based periods greater than 2 h and vertical wavelengths between 4 km and 20...

Arctic and Antarctic tropopause is formed under unique climate conditions, both in the troposphere and stratosphere. Individual patterns of polar tropopause anomalies are formed under dominance or competition of the tropospheric and stratospheric sources. We analyse the thermal tropopause climatology in the polar regions using National Centers for...

Results of a comparative analysis of quasi-stationary planetary wave (QSW) influences on total ozone column (TOC) distribution at 60° N and 60° S latitudes are presented. Total Ozone Mapping Spectrometer (TOMS) version 8 total ozone satellite data for years 1979–2003 were used to examine the longitudinal variation of ozone distribution. Three-month...

The Global Atmosphere Watch of WMO includes several stations in Antarctica that keep a close eye on the ozone layer during the ozone hole season. Observations made during the ozone holes from 2003 to 2010 will be compared to each other and interpreted in light of the meteorological conditions. Satellite observations will be used to get a more gener...

A seasonal analysis of the relationship between mesoscale orographic gravity wave activity and polar stratospheric cloud (PSC) composition occurrence around the whole of Antarctica is presented. Gravity wave variances are derived from temperature measurements made with the Constellation Observing System for Meteorology, Ionosphere and Climate (COSM...

The Antarctic ozone holes of 2008 and 2009 are reviewed from various perspectives, making use of a range of Australian data and analyses. In both years, ozone holes formed that were fairly typical of those observed since the late 1990s. The ozone hole of 2008 was somewhat larger than that of 2009. In 2009 the ozone hole developed more rapidly, but...

The Antarctic ozone hole of 2011 is reviewed from a variety of perspectives, making use of various data and analyses. The ozone hole of 2011 was relatively large in terms of maximum area, minimum ozone level and total ozone deficit, being ranked amongst the top ten in terms of severity of the 32 ozone holes adequately characterised since 1979. In p...

We present the first account of polar mesosphere winter echoes (PMWE) observed from the Southern Hemisphere (SH), using measurements from Davis, Antarctica (68.6°S; 78.0°E). PMWE were observed by mesosphere-stratosphere-troposphere (MST) radar during solar proton events (SPEs) and auroral substorms. We supplement the MST radar measurements with pro...