The semi-annual oscillation and equatorial tracer distributions

Gray, Lesley J.; PYLE, JA

doi:10.1256/smsqj.47206

Cited by 5 publications

(7 citation statements)

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“…Comparisons of the zonal wind SAO at the stratopause in CMAM (Medvedev and Klaassen, 2001) and observations (Hirota, 1978;Garcia et al, 1997) indicate that the positive anomalies in these tracers are associated with easterly wind shear and negative temperature anomalies while the negative anomalies in the tracers are associated with westerly wind shear and positive temperature anomalies. This is also consistent with the understanding of the SAO in long-lived tracers (e.g., Gray and Pyle, 1986;Ray et al, 1994).…”

Section: Comparisons Of Tropical Oscillationssupporting

confidence: 89%

“…5). This feature results from the downward movement associated with the westerly shear of the dynamical SAO at the equator and upward movement in the subtropics (Gray and Pyle, 1986). The double-peak feature also shows a quasi-biennial oscillation.…”

Section: N 2 O Comparisonsmentioning

confidence: 92%

“…Other studies have shown that the signal is driven by the tropical upwelling due to annual temperature oscillation (Randel et al, 2007) and by the Brewer-Dobson circulation (Schoeberl et al, 2008) in the lower stratosphere. The SAO and QBO in the chemical tracers are also determined by the wind and temperature oscillations associated with the middle atmospheric circulation (e.g., Gray and Pyle, 1986;Ray et al, 1994;Baldwin et al, 2001).…”

Section: Comparisons Of Tropical Oscillationsmentioning

confidence: 99%

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Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N2O), and methane (CH4) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

et al. 2009

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Abstract. Simulations of CO, N 2 O and CH 4 from a coupled chemistry-climate model (CMAM) are compared with satellite measurements from Odin Sub-Millimeter Radiometer (Odin/SMR), Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), and Aura Microwave Limb Sounder (Aura/MLS). Pressure-latitude cross-sections and seasonal time series demonstrate that CMAM reproduces the observed global CO, N 2 O, and CH 4 distributions quite well. Generally, excellent agreement with measurements is found between CO simulations and observations in the stratosphere and mesosphere. Differences between the simulations and the ACE-FTS observations are generally within 30%, and the differences between CMAM results and SMR and MLS observations are slightly larger. These differences are comparable with the difference between the instruments in the upper stratosphere and mesosphere. Comparisons of N 2 O show that CMAM results are usually within 15% of the measurements in the lower and middle stratosphere, and the observations are close to each other. However, the standard version of CMAM has a low N 2 O bias in the upper stratosphere. The CMAM CH 4 distribution also reproduces the observations in the lower stratosphere, but has a similar butCorrespondence to: J. J. Jin (jin@nimbus.yorku.ca) smaller negative bias in the upper stratosphere. The negative bias may be due to that the gravity drag is not fully resolved in the model. The simulated polar CO evolution in the Arctic and Antarctic agrees with the ACE and MLS observations. CO measurements from 2006 show evidence of enhanced descent of air from the mesosphere into the stratosphere in the Arctic after strong stratospheric sudden warmings (SSWs). CMAM also shows strong descent of air after SSWs. In the tropics, CMAM captures the annual oscillation in the lower stratosphere and the semiannual oscillations at the stratopause and mesopause seen in Aura/MLS CO and N 2 O observations and in Odin/SMR N 2 O observations. The Odin/SMR and Aura/MLS N 2 O observations also show a quasi-biennial oscillation (QBO) in the upper stratosphere, whereas, the CMAM does not have QBO included. This study confirms that CMAM is able to simulate middle atmospheric transport processes reasonably well.

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Section: Comparisons Of Tropical Oscillationssupporting

confidence: 89%

Section: N 2 O Comparisonsmentioning

confidence: 92%

Section: Comparisons Of Tropical Oscillationsmentioning

confidence: 99%

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Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N2O), and methane (CH4) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

et al. 2009

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“…2b) reveals a 5% significant peak at 3.5 yr (42 months; labeled P). The other 5% significant spectral peaks are attributed to the QBO (28 months; Q), the QBO-AB (21 months; Q 1 ) (Camp et al 2003;Tung and Yang 1994a,b), the residual annual cycle (A), and the semiannual oscillation (6 months, A 1 ) (Gray and Pyle 1986). Because the annual cycle has a broad power spectrum, there is some residual annual cycle left after removing the monthly mean from the data.…”

Section: A Results For Northern Hemispheric Column Omentioning

confidence: 99%

Interannual Variability and Trends of Extratropical Ozone. Part I: Northern Hemisphere

et al. 2008

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The authors apply principal component analysis (PCA) to the extratropical total column ozone from the combined merged ozone data product and the European Centre for Medium-Range Weather Forecasts assimilated ozone from January 1979 to August 2002. The interannual variability (IAV) of extratropical O 3 in the Northern Hemisphere (NH) is characterized by four main modes. Attributable to dominant dynamical effects, these four modes account for nearly 60% of the total ozone variance in the NH. The patterns of variability are distinctly different from those derived for total O 3 in the tropics. To relate the derived patterns of O 3 to atmospheric dynamics, similar decompositions are performed for the 30-100-hPa geopotential thickness. The results reveal intimate connections between the IAV of total ozone and the atmospheric circulation.The first two leading modes are nearly zonally symmetric and represent the connections to the annular modes and the quasi-biennial oscillation. The other two modes exhibit in-quadrature, wavenumber-1 structures that, when combined, describe the displacement of the polar vortices in response to planetary waves. In the NH, the extrema of these combined modes have preferred locations that suggest fixed topographical and land-sea thermal forcing of the involved planetary waves. Similar spatial patterns and trends in extratropical column ozone are simulated by the Goddard Earth Observation System chemistry-climate model (GEOS-CCM).The decreasing O 3 trend is captured in the first mode. The largest trend occurs at the North Pole, with values ϳϪ1 Dobson Unit (DU) yr Ϫ1. There is almost no trend in tropical O 3 . The trends derived from PCA are confirmed using a completely independent method, empirical mode decomposition, for zonally averaged O 3 data. The O 3 trend is also captured by mode 1 in the GEOS-CCM, but the decrease is substantially larger than that in the real atmosphere.

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“…As a review, it is noted that the original, LIMS V5 H 2 O distributions were used to examine issues related to stratospheric chemistry (e.g., LeTexier et al, 1988;Garcia and Solomon, 1994) and transport (e.g., Gray and Pyle, 1986;Butchart and Remsberg, 1986;and Gille et al, 1987). Its H 2 O distributions were also used in studies of the stratospheric budget of water vapor, and, in particular, to estimate the H 2 O mixing ratio (or [H 2 O] e ) as it enters the tropical stratosphere from below (Jones et al, 1986;Hansen and Robinson, 1989).…”

Section: Introductionmentioning

confidence: 99%

On the quality of the Nimbus 7 LIMS Version 6 water vapor profiles and distributions

et al. 2009

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Abstract. This report describes the quality of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) water vapor (H 2 O) profiles of 1978/79 that were processed with a Version 6 (V6) algorithm and archived in 2002. The V6 profiles incorporate a better knowledge of the instrument attitude for the LIMS measurements along its orbits, leading to improvements for its temperature profiles and for the registration of its water vapor radiances with pressure. As a result, the LIMS V6 zonal-mean distributions of H 2 O exhibit better hemispheric symmetry than was the case from the original Version 5 (V5) dataset that was archived in 1982. Estimates of the precision and accuracy of the V6 H 2 O profiles are developed and provided. Individual profiles have a precision of order 5% and an estimated accuracy of about 19% at 3 hPa, 14% at 10 hPa, and 26% at 50 hPa. Profile segments within about 2 km of the tropopause are often affected by emissions from clouds that appear in the finite field-of-view of the de- vapor dataset is of good quality for studies of the near globalscale chemistry and transport for pressure levels from 3 hPa to about 70 to 100 hPa.

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The semi-annual oscillation and equatorial tracer distributions

Cited by 5 publications

References 0 publications

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N<sub>2</sub>O), and methane (CH<sub>4</sub>) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N<sub>2</sub>O), and methane (CH<sub>4</sub>) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

Interannual Variability and Trends of Extratropical Ozone. Part I: Northern Hemisphere

On the quality of the Nimbus 7 LIMS Version 6 water vapor profiles and distributions

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The semi-annual oscillation and equatorial tracer distributions

Cited by 5 publications

References 0 publications

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O), and methane (CH&lt;sub&gt;4&lt;/sub&gt;) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O), and methane (CH&lt;sub&gt;4&lt;/sub&gt;) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

Interannual Variability and Trends of Extratropical Ozone. Part I: Northern Hemisphere

On the quality of the Nimbus 7 LIMS Version 6 water vapor profiles and distributions

Contact Info

Product

Resources

About

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N<sub>2</sub>O), and methane (CH<sub>4</sub>) with observations from Odin/SMR, ACE-FTS, and Aura/MLS

Comparison of CMAM simulations of carbon monoxide (CO), nitrous oxide (N<sub>2</sub>O), and methane (CH<sub>4</sub>) with observations from Odin/SMR, ACE-FTS, and Aura/MLS