Detecting environmental changes and trends

Weatherhead, Elizabeth; Stevermer, A.; Schwartz, Barry E.

doi:10.1016/s1474-7065(02)00019-0

Cited by 57 publications

(73 citation statements)

References 13 publications

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“…transport patterns, rain, radiation, temperature). Long time series of high-quality measurement data are required in order to detect the trend above the large interannual variation (Staehelin, 2003;Weatherhead et al, 1998;Weatherhead et al, 2002) and the sensitivity of the extracted trends to location necessitates that this is done at a range of sites to ensure representativeness and permit attribution of the observed changes. Jonson et al (2006) discussed some of these effects in relation to ozone trends.…”

Section: Changing Ozone -A Brief Historymentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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Abstract. Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone-climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales.

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Section: Changing Ozone -A Brief Historymentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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“…Our ability to detect trends in environmental data depends on the size of the trend, the magnitude of the variability, and the autocorrelation of the observations (Weatherhead et al, 1998;Weatherhead et al, 2002;Tiao et al, 1990). To confidently detect a trend in a trace gas, it must be large relative to both the natural variability and to the measurement uncertainty, or alternatively one needs many years of observations.…”

Section: The Impact Of Asian Emissions Of Omentioning

confidence: 99%

“…Detecting trends in trace species amidst large underlying variability presents a challenge (Weatherhead et al, 2002). Later in this paper, we use the 2008-2010 MBO data to calculate the observational requirements for detecting a possible increase in PAN mixing ratios over the northeast Pacific due to changes in Asian precursor emissions.…”

Section: Comparison To Other Free Tropospheric Pan Observations In Thmentioning

confidence: 99%

“…This hypothesis followed from model simulations suggesting that the relative trend in PAN caused by rising Asian NO x emissions would be approximately 4 times larger than that of O 3 . Detecting trends in atmospheric trace species, such as O 3 or PAN, depends on the size of the trend, the magnitude of the variability, and the autocorrelation of the observations (Weatherhead et al, 1998(Weatherhead et al, , 2002Tiao et al, 1990). The data presented in Fig.…”

Section: Detecting Changes In Pan and O 3 Over Northmentioning

confidence: 99%

“…By sampling average PAN from the multi-year MBO dataset, we are able to include both synoptic scale and interannual variability in the calculation. We incorporate the actual variability in PAN, regardless of whether we fully understand all the drivers, so we can develop a reasonable expectation of when possible trends could be detected (Weatherhead et al, 2002). We considered a range of hypothetical future trends, and for each trend a time series like Fig.…”

Section: Detecting Changes In Pan and O 3 Over Northmentioning

confidence: 99%

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Free tropospheric peroxyacetyl nitrate (PAN) and ozone at Mount Bachelor: potential causes of variability and timescale for trend detection

2011

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Abstract. We report on the first multi-year springtime measurements of PAN in the free troposphere over the US Pacific Northwest. The measurements were made at the summit of Mount Bachelor (43.979 • N, 121.687 • W; 2.7 km a.s.l.) by gas chromatography with electron capture detector during spring 2008, 2009 and 2010. This dataset provides an observational estimate of the month-to-month and springtime interannual variability of PAN mixing ratios in this region. Springtime seasonal mean (1 April-20 May) PAN mixing ratios at Mount Bachelor varied from 100 pptv to 152 pptv. The standard deviation of the three seasonal means was 28 pptv, 21 % of the springtime mean. We summarize the interannual variability in three factors expected to drive PAN variability: biomass burning, transport efficiency over the central and eastern Pacific, and transport temperature. Zhang et al. (2008) used the GEOS-Chem global chemical transport model to show that rising Asian NO x emissions from 2000 to 2006 resulted in a relatively larger positive trend in PAN than O 3 over western North America. However the model results only considered monotonic changes in Asian emissions, whereas other factors, such as biomass burning, isoprene emissions or climate change can induce greater variability in the atmospheric concentrations and thus extend the time needed for trend detection. We combined the observed variability in PAN and O 3 at Mount Bachelor with a range of possible future trends in these species to determine the observational requirements to detect such trends. Though the relative increase in PAN is expected to be larger than that of O 3 , PAN is more variable. If PAN mixing ratios are currently increasing at a rate of 4 % per year due to rising Asian Correspondence to: E. V. Fischer (efischer@atmos.washington.edu) emissions, we would detect a trend with 13 years of measurements at a site like Mount Bachelor. If the corresponding trend in O 3 is 1 % per year, the trends in O 3 and PAN would be detected on approximately the same timescale.

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Detection of carbon monoxide trends in the presence of interannual variability

Strode

Pawson

2013

JGR Atmospheres

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[1] Trends in fossil fuel emissions are a major driver of changes in atmospheric CO, but detection of trends in CO from anthropogenic sources is complicated by the presence of large interannual variability (IAV) in biomass burning. We use a multiyear model simulation of CO with year-specific biomass burning to predict the number of years needed to detect the impact of changes in Asian anthropogenic emissions on downwind regions. Our study includes two cases for changing anthropogenic emissions: a stepwise change of 15% and a linear trend of 3% yr À1 . We first examine how well the model reproduces the observed IAV of CO over the North Pacific, since this variability impacts the time needed to detect significant anthropogenic trends. The modeled IAV over the North Pacific correlates well with that seen from the Measurements of Pollution in the Troposphere (MOPITT) instrument but underestimates the magnitude of the variability. The model predicts that a 3% yr À1 trend in Asian anthropogenic emissions would lead to a statistically significant trend in CO surface concentration in the western United States within 12 years, and accounting for Siberian boreal biomass-burning emissions greatly reduces the number of years needed for trend detection. Combining the modeled trend with the observed MOPITT variability at 500 hPa, we estimate that the 3% yr À1 trend could be detectable in satellite observations over Asia in approximately a decade. Our predicted timescales for trend detection highlight the importance of long-term measurements of CO from satellites.

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Detecting environmental changes and trends

Cited by 57 publications

References 13 publications

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Free tropospheric peroxyacetyl nitrate (PAN) and ozone at Mount Bachelor: potential causes of variability and timescale for trend detection

Detection of carbon monoxide trends in the presence of interannual variability

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