The Climatology of Australian Aerosol
Airborne particles or aerosols have long been recognised for their major contribution to uncertainty in climate change. In addition, aerosol amounts must be known for accurate atmospheric correction of remotely sensed images, and are required to accurately gauge the available solar resource. However...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/5131/2017/acp-17-5131-2017.pdf |
| _version_ | 1828188407951523840 |
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| author | R. M. Mitchell B. W. Forgan S. K. Campbell |
| author_facet | R. M. Mitchell B. W. Forgan S. K. Campbell |
| author_sort | R. M. Mitchell |
| collection | DOAJ |
| description | Airborne particles or aerosols have long been recognised for their major
contribution to uncertainty in climate change. In addition, aerosol amounts
must be known for accurate atmospheric correction of remotely sensed images,
and are required to accurately gauge the available solar resource. However,
despite great advances in surface networks and satellite retrievals over
recent years, long-term continental-scale aerosol data sets are lacking. Here
we present an aerosol assessment over Australia based on combined sun
photometer measurements from the Bureau of Meteorology Radiation Network and
CSIRO/AeroSpan. The measurements are continental in coverage, comprising 22
stations, and generally decadal in timescale, totalling 207 station-years.
Monthly climatologies are given at all stations. Spectral decomposition shows
that the time series can be represented as a weighted sum of sinusoids with
periods of 12, 6 and 4 months, corresponding to the annual cycle and its
second and third harmonics. Their relative amplitudes and phase relationships
lead to sawtooth-like waveforms sharply rising to an austral spring peak,
with a slower decline often including a secondary peak during the summer. The
amplitude and phase of these periodic components show significant regional
change across the continent. Fits based on this harmonic analysis are used to
separate the periodic and episodic components of the aerosol time series. An
exploratory classification of the aerosol types is undertaken based on
(a) the relative periodic amplitudes of the Ångström exponent and
aerosol optical depth, (b) the relative amplitudes of the 6- and 4-month
harmonic components of the aerosol optical depth, and (c) the ratio of
episodic to periodic variation in aerosol optical depth. It is shown that
Australian aerosol can be broadly grouped into three classes: tropical, arid
and temperate. Statistically significant decadal trends are found at 4 of the
22 stations. Despite the apparently small associated declining trends in
mid-visible aerosol optical depth of between 0.001 and 0.002 per year, these
trends are much larger than those projected to occur due to declining
emissions of anthropogenic aerosols from the Northern Hemisphere. There is
remarkable long-range coherence in the aerosol cycle across the continent,
suggesting broadly similar source characteristics, including a possible role
for intercontinental transport of biomass burning aerosol. |
| first_indexed | 2024-04-12T07:49:45Z |
| format | Article |
| id | doaj.art-205799c3fb96496396c6dc4a88831418 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-12T07:49:45Z |
| publishDate | 2017-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-205799c3fb96496396c6dc4a888314182022-12-22T03:41:37ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242017-04-011785131515410.5194/acp-17-5131-2017The Climatology of Australian AerosolR. M. Mitchell0B. W. Forgan1S. K. Campbell2CSIRO Oceans and Atmosphere, Yarralumla, GPO Box 1700, Canberra, ACT, AustraliaAustralian Bureau of Meteorology, P.O. Box 1289K, Melbourne, AustraliaCSIRO Oceans and Atmosphere, Yarralumla, GPO Box 1700, Canberra, ACT, AustraliaAirborne particles or aerosols have long been recognised for their major contribution to uncertainty in climate change. In addition, aerosol amounts must be known for accurate atmospheric correction of remotely sensed images, and are required to accurately gauge the available solar resource. However, despite great advances in surface networks and satellite retrievals over recent years, long-term continental-scale aerosol data sets are lacking. Here we present an aerosol assessment over Australia based on combined sun photometer measurements from the Bureau of Meteorology Radiation Network and CSIRO/AeroSpan. The measurements are continental in coverage, comprising 22 stations, and generally decadal in timescale, totalling 207 station-years. Monthly climatologies are given at all stations. Spectral decomposition shows that the time series can be represented as a weighted sum of sinusoids with periods of 12, 6 and 4 months, corresponding to the annual cycle and its second and third harmonics. Their relative amplitudes and phase relationships lead to sawtooth-like waveforms sharply rising to an austral spring peak, with a slower decline often including a secondary peak during the summer. The amplitude and phase of these periodic components show significant regional change across the continent. Fits based on this harmonic analysis are used to separate the periodic and episodic components of the aerosol time series. An exploratory classification of the aerosol types is undertaken based on (a) the relative periodic amplitudes of the Ångström exponent and aerosol optical depth, (b) the relative amplitudes of the 6- and 4-month harmonic components of the aerosol optical depth, and (c) the ratio of episodic to periodic variation in aerosol optical depth. It is shown that Australian aerosol can be broadly grouped into three classes: tropical, arid and temperate. Statistically significant decadal trends are found at 4 of the 22 stations. Despite the apparently small associated declining trends in mid-visible aerosol optical depth of between 0.001 and 0.002 per year, these trends are much larger than those projected to occur due to declining emissions of anthropogenic aerosols from the Northern Hemisphere. There is remarkable long-range coherence in the aerosol cycle across the continent, suggesting broadly similar source characteristics, including a possible role for intercontinental transport of biomass burning aerosol.http://www.atmos-chem-phys.net/17/5131/2017/acp-17-5131-2017.pdf |
| spellingShingle | R. M. Mitchell B. W. Forgan S. K. Campbell The Climatology of Australian Aerosol Atmospheric Chemistry and Physics |
| title | The Climatology of Australian Aerosol |
| title_full | The Climatology of Australian Aerosol |
| title_fullStr | The Climatology of Australian Aerosol |
| title_full_unstemmed | The Climatology of Australian Aerosol |
| title_short | The Climatology of Australian Aerosol |
| title_sort | climatology of australian aerosol |
| url | http://www.atmos-chem-phys.net/17/5131/2017/acp-17-5131-2017.pdf |
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