A new formulation of equivalent effective stratospheric chlorine (EESC)

Newman, Paul A.; Daniel, J. S.; Waugh, D. W.; Nash, Eric R.

doi:10.5194/acp-7-4537-2007

Cited by 279 publications

(380 citation statements)

References 26 publications

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“…This significance comes mainly from the fitting to the downward trend prior to 2000. EESC is a modeled representation of the amount of chlorine and bromine in the atmosphere available to destroy stratospheric ozone at a given time and location, based on measurements of ozone-depleting substances in the troposphere, age of air, and the fractional release rates of chlorine and bromine from various chemical constituents (Newman et al, 2007). Our best current understanding, as represented in chemistry climate models, predicts that stratospheric ozone varies linearly with EESC (e.g., Newman et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…gov/SBUV_CDR/. Long-term variability in the ozone profile record is represented by various proxy time series: (1) EESC data are from http://acdb-ext.gsfc.nasa.gov/Data_services/automailer/ (Newman et al, 2007); (2) solar cycle data are from the Penticton/Ottawa 10.7 cm solar radio flux measurement record available at http:// www.ngdc.noaa.gov/stp/solar/flux.html; (3) QBO data are available at http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/qbo/index. html#access (Naujokat, 1986); (4) Multivariate ENSO Index (MEI) data are found at http://www.esrl.noaa.gov/psd/enso/mei/ Timlin, 1993, 1998); (5) Volcanic aerosols are from 2-D model simulations as described in and Stolarski et al (2006).…”

Section: Discussionmentioning

confidence: 99%

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Estimating uncertainties in the SBUV Version 8.6 merged profile ozone data set

et al. 2017

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Abstract. The combined record of total and profile ozone measurements from the solar backscatter ultraviolet (SBUV) and SBUV/2 series of instruments, known as the SBUV Merged Ozone Data (MOD) product, constitutes the longest satellite-based ozone time series from a single instrument type and as such plays a key role in ozone trend analyses.Following the approach documented in to analyze the merging uncertainties in the MOD total ozone record, we use Monte Carlo simulations to estimate the potential for uncertainties in the calibration and drift of individual instruments in the profile ozone merged data set. We focus our discussion on the trends and associated merging uncertainty since 2001 in an effort to verify the start of ozone recovery as predicted by chemistry climate models. We find that merging uncertainty dominates the overall estimated uncertainty when considering only the 15 years of data since 2001. We derive trends versus pressure level for the MOD data set that are positive in the upper stratosphere as expected for ozone recovery. These trends appear to be significant when only statistical uncertainties are included but become not significant at the 2σ level when instrument uncertainties are accounted for. However, when we use the entire data set from 1979 through 2015 and fit to the EESC (equivalent effective stratospheric chlorine) we find statistically significant fits throughout the upper stratosphere at all latitudes. This implies that the ozone profile data remain consistent with our expectation that chlorine is the dominant ozone forcing term.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Estimating uncertainties in the SBUV Version 8.6 merged profile ozone data set

et al. 2017

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“…The QBO(t), QBO_orth(t) and ENSO(t) were calculated in the same way as in the model but using the ERAI zonal wind and SST data (Dee et al, 2011). ESC(t) is replaced with EESC(t) (Equivalent Effective Stratospheric Chlorine), which estimates stratospheric Cl y and Br y from their tropospheric source gases, here assuming the atmospheric circulation with the age of air spectrum with the mean of 3 years (as was done in SPARC, 2010, following Newman et al, 2007). The MLR analysis is performed over 1979-2008 for ERAI, and over 25…”

Section: Trend 10mentioning

confidence: 99%

“…For the MLR analysis of the UM-UKCA data, ESC(t) is the Effective Stratospheric Chlorine (Eyring et al, 2007) and is defined as the global monthly mean Cl y + 60×Br y at 20 km, as was done in SPARC (2010) following Newman et al (2007).…”

Section: Trend 10mentioning

confidence: 99%

Simulating the atmospheric response to the 11-year solar cycle forcing with the UM-UKCA model: the role of detection method and natural variability

Bednarz¹,

Maycock²,

Telford³

et al. 2018

Preprint

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The 11-year solar cycle forcing is recognised as a potentially important atmospheric forcing; however, there remain uncertainties in characterising the effects of the solar variability on the atmosphere from observations and models. Here we 15 present the first detailed assessment of the atmospheric response to the 11-year solar cycle in the UM-UKCA chemistryclimate model using an ensemble of integrations over the recent past. Comparison of the model simulations is made with observations and reanalysis. Importantly, in contrast to the majority of previous studies of the solar cycle impacts, we pay particular attention to the role of detection method by comparing the results diagnosed using both a composite and a multiple linear regression method. We show that stratospheric solar responses diagnosed using both techniques largely agree with 20 each other within the associated uncertainties; however, the results show that apparently different signals can be identified by the methods in the troposphere and in the tropical lower stratosphere. Lastly, we focus on the role of internal atmospheric variability on the detection of the 11-year solar responses by comparing the results diagnosed from individual model ensemble members (as opposed to those diagnosed from the full ensemble). We show overall agreement between the ensemble members in the tropical and mid-latitude mid-stratosphere-to-lower-mesosphere, but larger apparent differences at 25 NH high latitudes during the dynamically active season. Our results highlight the need for long data sets for confident detection of solar cycle impacts in the atmosphere, as well as for more research on possible interdependence of the solar cycle forcing with other atmospheric forcings and processes (e.g. QBO, ENSO… etc.).Atmos. Chem. Phys. Discuss., https://doi

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“…T(t) is constructed using EESC (Equivalent Effective Stratospheric Chlorine) time series (Chapter 5 of WMO (2011)) for ozone, inorganic chlorine loading time series for HCl and ClONO 2 or simply time for N 2 O, CH 4 , HNO 3 and NO 2 as trend explanatory variables. The formulation of EESC, a proxy for the combined total inorganic chlorine (Cly) and bromine (Bry) loading, is taken from WMO (2011) so that it accounts for the age-of-air spectrum and age-of-air dependent fractional release values (Newman et al, 2007). Note that EESC peaked in 1997 at mid-latitudes and 2002 at high latitudes (WMO, 2011).…”

Section: Multiple Regression Modelmentioning

confidence: 99%

Evaluation of the inter-annual variability of stratospheric chemical composition in chemistry-climate models using ground-based multi species time series

Poulain

Bekki

Marchand

et al. 2016

Journal of Atmospheric and Solar-Terrestrial Physics

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A new formulation of equivalent effective stratospheric chlorine (EESC)

Cited by 279 publications

References 26 publications

Estimating uncertainties in the SBUV Version 8.6 merged profile ozone data set

Estimating uncertainties in the SBUV Version 8.6 merged profile ozone data set

Simulating the atmospheric response to the 11-year solar cycle forcing with the UM-UKCA model: the role of detection method and natural variability

Evaluation of the inter-annual variability of stratospheric chemical composition in chemistry-climate models using ground-based multi species time series

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