Summertime stratospheric processes at northern mid-latitudes: comparisons between MANTRA balloon measurements and the Canadian Middle Atmosphere Model

Melo, S. M. L.; Blatherwick, R. D.; Davies, J.; Fogal, P. F.; Grandpré, J. de; McConnell, J. C.; McElroy, C. T.; McLandress, C.; Murcray, F. J.; Olson, J. R.; Semeniuk, K.; Shepherd, Theodore G.; Strong, Kimberly; Tarasick, D. W.; Williams-Rioux, B. J.

doi:10.5194/acp-8-2057-2008

Cited by 9 publications

(10 citation statements)

References 52 publications

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“…The dynamical core and chemistry scheme are described by Beagley et al [1997] andde Grandpré et al [1997], respectively. The distributions of chemical species in the CMAM have been seen to generally compare well with observations [e.g., de Grandpré et al, 2000;Farahani et al, 2007;Hegglin and Shepherd, 2007;Jin et al, 2005;Jin et al, 2009;Melo et al, 2008]. Simulated chemical fields from the last ten years (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) of the CMAM REF1 simulation described by Eyring et al [2006] are used here.…”

Section: Tropical Variability In the Cmammentioning

confidence: 83%

Validating the reported random errors of ACE‐FTS measurements

Toohey¹,

Strong²,

Bernath³

et al. 2010

J. Geophys. Res.

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[1] In order to validate the reported precision of space-based atmospheric composition measurements, validation studies often focus on measurements in the tropical stratosphere, where natural variability is weak. The scatter in tropical measurements can then be used as an upper limit on single-profile measurement precision. Here we introduce a method of quantifying the scatter of tropical measurements which aims to minimize the effects of short-term atmospheric variability while maintaining large enough sample sizes that the results can be taken as representative of the full data set. We apply this technique to measurements of O 3 , HNO 3 , CO, H 2 O, NO, NO 2 , N 2 O, CH 4 , CCl 2 F 2 , and CCl 3 F produced by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). Tropical scatter in the ACE-FTS retrievals is found to be consistent with the reported random errors (RREs) for H 2 O and CO at altitudes above 20 km, validating the RREs for these measurements. Tropical scatter in measurements of NO, NO 2 , CCl 2 F 2 , and CCl 3 F is roughly consistent with the RREs as long as the effect of outliers in the data set is reduced through the use of robust statistics. The scatter in measurements of O 3 , HNO 3 , CH 4 , and N 2 O in the stratosphere, while larger than the RREs, is shown to be consistent with the variability simulated in the Canadian Middle Atmosphere Model. This result implies that, for these species, stratospheric measurement scatter is dominated by natural variability, not random error, which provides added confidence in the scientific value of single-profile measurements.

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Section: Tropical Variability In the Cmammentioning

confidence: 83%

Validating the reported random errors of ACE‐FTS measurements

Toohey¹,

Strong²,

Bernath³

et al. 2010

J. Geophys. Res.

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“…The model has a comprehensive middle atmosphere photochemical scheme as well as heterogeneous chemistry on ice and supersaturated ternary solution (STS) polar stratospheric clouds (PSCs) (de Grandpré et al, 1997(de Grandpré et al, , 2000 which can capture NO x and HO x production and decay, as well as interaction with chlorine and bromine chemistry (Melo et al, 2008;Brohede et al, 2008). The heterogeneous chemistry scheme does not include processing on nitric acid trihydrate (NAT) particles as well as the associated denitrification.…”

Section: Description Of the Model And Simulationsmentioning

confidence: 99%

Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

et al. 2011

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Abstract. The impact of NO x and HO x production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

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“…The dynamical core and chemistry scheme are described by Beagley et al (1997) and de Grandpré et al The distributions of chemical species in the CMAM have been seen to generally compare well with observations (e.g. de Grandpré et al, 2000;Farahani et al, 2007;Hegglin and Shepherd, 2007;Jin et al, 2005;Jin et al, 2009;Melo et al, 2008). While this version of CMAM does not simulate the quasi-biennial oscillation and, thus, underestimates interannual variability in the tropics, the intra-month variability appears to be of realistic magnitude (see Chapter 7 of SPARC CCMVal, 2010; Toohey et al, 2010).…”

Section: Model Fieldsmentioning

confidence: 78%

Climatologies from satellite measurements: the impact of orbital sampling on the standard error of the mean

Toohey

Clarmann

2013

Atmos. Meas. Tech.

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Climatologies of atmospheric observations are often produced by binning measurements according to latitude and calculating zonal means. The uncertainty in these climatological means is characterised by the standard error of the mean (SEM). However, the usual estimator of the SEM, i.e., the sample standard deviation divided by the square root of the sample size, holds only for uncorrelated randomly sampled measurements. Measurements of the atmospheric state along a satellite orbit cannot always be considered as independent because (a) the time-space interval between two nearest observations is often smaller than the typical scale of variations in the atmospheric state, and (b) the regular time-space sampling pattern of a satellite instrument strongly deviates from random sampling. We have developed a numerical experiment where global chemical fields from a chemistry climate model are sampled according to real sampling patterns of satellite-borne instruments. As case studies, the model fields are sampled using sampling patterns of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and Atmospheric Chemistry Experiment Fourier-Transform Spectrometer (ACE-FTS) satellite instruments. Through an iterative subsampling technique, and by incorporating information on the random errors of the MIPAS and ACE-FTS measurements, we produce empirical estimates of the standard error of monthly mean zonal mean model O₃ in 5° latitude bins. We find that generally the classic SEM estimator is a conservative estimate of the SEM, i.e., the empirical SEM is often less than or approximately equal to the classic estimate. Exceptions occur only when natural variability is larger than the random measurement error, and specifically in instances where the zonal sampling distribution shows non-uniformity with a similar zonal structure as variations in the sampled field, leading to maximum sensitivity to arbitrary phase shifts between the sample distribution and sampled field. The occurrence of such instances is thus very sensitive to slight changes in the sampling distribution, and to the variations in the measured field. This study highlights the need for caution in the interpretation of the oft-used classically computed SEM, and outlines a relatively simple methodology that can be used to assess one component of the uncertainty in monthly mean zonal mean climatologies produced from measurements from satellite-borne instruments

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Summertime stratospheric processes at northern mid-latitudes: comparisons between MANTRA balloon measurements and the Canadian Middle Atmosphere Model

Cited by 9 publications

References 52 publications

Validating the reported random errors of ACE‐FTS measurements

Validating the reported random errors of ACE‐FTS measurements

Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

Climatologies from satellite measurements: the impact of orbital sampling on the standard error of the mean

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