scholarly journals Vertical distributions of N<sub>2</sub>O isotopocules in the equatorial stratosphere

2017 ◽  
Author(s):  
Sakae Toyoda ◽  
Naohiro Yoshida ◽  
Shinji Morimoto ◽  
Shuji Aoki ◽  
Takakiyo Nakazawa ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Vertical Gradient ◽  
Enrichment Factors ◽  
Equatorial Pacific ◽  
Vertical Profiles ◽  
Mixing Ratio ◽  
Air Samples ◽  
Eastern Equatorial Pacific ◽  
Vertical Distributions ◽  
Middle Stratosphere

Abstract. Vertical profiles of nitrous oxide (N2O) and its isotopocules, isotopically substituted molecules, were obtained over the equator at altitudes of 16–30 km. Whole air samples were collected using newly developed balloon-borne compact cryogenic samplers over the Eastern Equatorial Pacific in 2012 and Biak Island, Indonesia in 2015. They were examined in the laboratory using gas chromatography and mass spectrometry. The mixing ratio and isotopocule ratios of N2O in the equatorial stratosphere showed a weaker vertical gradient than the previously reported profiles in the subtropical and mid-latitude and high-latitude stratosphere. From the relation between the mixing ratio and isotopocule ratios, further distinct characteristics were found over the equator: (1) Observed isotopocule enrichment factors (&amp;varepsilon; values) in the middle stratosphere (25–30 km) are almost equal to &amp;varepsilon; values reported from broadband photolysis experiments conducted in the laboratory. (2) &amp;varepsilon; values in the lower stratosphere (

scholarly journals Vertical distributions of N<sub>2</sub>O isotopocules in the equatorial stratosphere

2018 ◽  
Vol 18 (2) ◽  
pp. 833-844 ◽  
Author(s):  
Sakae Toyoda ◽  
Naohiro Yoshida ◽  
Shinji Morimoto ◽  
Shuji Aoki ◽  
Takakiyo Nakazawa ◽  
...  
Keyword(s):  
High Latitude ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Mixing Ratio ◽  
Residual Circulation ◽  
Chemical Transport Model ◽  
Eastern Equatorial Pacific ◽  
Middle Stratosphere

Abstract. Vertical profiles of nitrous oxide (N2O) and its isotopocules, isotopically substituted molecules, were obtained over the Equator at altitudes of 16–30 km. Whole air samples were collected using newly developed balloon-borne compact cryogenic samplers over the eastern equatorial Pacific in 2012 and Biak Island, Indonesia, in 2015. They were examined in the laboratory using gas chromatography and mass spectrometry. The mixing ratio and isotopocule ratios of N2O in the equatorial stratosphere showed a weaker vertical gradient than the previously reported profiles in the subtropical and mid-latitude and high-latitude stratosphere. From the relation between the mixing ratio and isotopocule ratios, further distinct characteristics were found over the Equator: (1) observed isotopocule fractionations (ε values) in the middle stratosphere (25–30 km or [N2O] < ca. 260 nmol mol−1) are almost equal to ε values reported from broadband photolysis experiments conducted in the laboratory; (2) ε values in the lower stratosphere (< ca. 25 km or [N2O] > ca. 260 nmol mol−1) are about half of the experimentally obtained values, being slightly larger than those observed in the mid-latitude and high-latitude lower stratosphere ([N2O] > ca. 170 nmol mol−1). These results from the deep tropics suggest the following. (i) The timescale for quasi-horizontal mixing between tropical and mid-latitude air in the tropical middle stratosphere is sufficiently slow relative to the tropical upwelling rate that isotope fractionation approaches the Rayleigh limit for N2O photolysis. (ii) The air in the tropical lower stratosphere is exchanged with extratropical air on a timescale that is shorter than that of photochemical decomposition of N2O. Previously observed ε values, which are invariably smaller than those of photolysis, can be explained qualitatively using a three-dimensional chemical transport model and using a simple model that assumes mixing of “aged” tropical air and extratropical air during residual circulation. Results show that isotopocule ratios are useful to examine the stratospheric transport scheme deduced from tracer–tracer relations.

scholarly journals Long-term observation of mass-independent oxygen isotope anomaly in stratospheric CO<sub>2</sub>

2008 ◽  
Vol 8 (20) ◽  
pp. 6189-6197 ◽  
Author(s):  
S. Kawagucci ◽  
U. Tsunogai ◽  
S. Kudo ◽  
F. Nakagawa ◽  
H. Honda ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Middle Atmosphere ◽  
Isotope Composition ◽  
Mixing Ratio ◽  
Least Squares Regression ◽  
Air Samples ◽  
Mixing Ratios ◽  
Long Term Observation ◽  
Isotope Correlation ◽  
Middle Stratosphere

Abstract. Stratospheric and upper tropospheric air samples were collected during 1994–2004 over Sanriku, Japan and in 1997 over Kiruna, Sweden. Using these archived air samples, we determined the triple oxygen-isotope composition of stratospheric CO2 and the N2O mixing ratio. The maximum Δ17OCO2 value of +12.2‰, resembling that observed previously in the mesosphere at 60 km height, was found in the middle stratosphere over Kiruna at 25.6 km height, suggesting that upper stratospheric and mesospheric air descended to the middle stratosphere through strong downward advection. A least-squares regression analysis of our observations on a δ18OCO2−δ17OCO2 plot (r2>0.95) shows a slope of 1.63±pm0.10, which is similar to the reported value of 1.71±0.06, thereby confirming the linearity of three isotope correlation with the slope of 1.6–1.7 in the mid-latitude lower and middle stratosphere. The slope decrease with increasing altitude and a curvy trend in three-isotope correlation reported from previous studies were not statistically significant. Using negative linear correlations of Δ17OCO2 and δ18OCO2 with the N2O mixing ratio, we quantified triple oxygen-isotope fluxes of CO2 to the troposphere as +48‰ GtC/yr (Δ17OCO2) and +38‰ GtC/yr (δ18OCO2) with ~30% uncertainty. Comparing recent model results and observations, underestimation of the three isotope slope and the maximum Δ17OCO2 value in the model were clarified, suggesting a smaller O2 photolysis contribution than that of the model. Simultaneous observations of δ18OCO2, δ17OCO2, and N2O mixing ratios can elucidate triple oxygen isotopes in CO2 and clarify complex interactions among physical, chemical, and photochemical processes occurring in the middle atmosphere.

scholarly journals Contribution of horizontal and vertical advection to the formation of small-scale vertical structures of ozone in the lower and middle stratosphere at Fairbanks, Alaska

2019 ◽  
Author(s):  
Miho Yamamori ◽  
Yasuhiro Murayama ◽  
Kazuo Shibasaki ◽  
Isao Murata ◽  
Kaoru Sato
Keyword(s):  
Dominant Role ◽  
Potential Temperature ◽  
Vertical Gradient ◽  
Small Scale ◽  
Mixing Ratio ◽  
Horizontal Advection ◽  
Vertical Advection ◽  
Background Ozone ◽  
Using Data ◽  
Middle Stratosphere

Abstract. The contribution of vertical and horizontal advection to the production of small-scale vertical ozone structures was investigated using data from an ozonesonde observation performed at intervals of 3 h in Fairbanks (64.8N, 147.9W), Alaska. The dominant vertical scales of the ozone mixing ratio were determined to be 2–5 km, which were similar to those of horizontal winds and the temperature of the lower and middle stratosphere, using spectral analysis. Ozone fluctuations due to vertical advection were estimated from the potential temperature fluctuation and vertical gradient of the background ozone mixing ratio. Residual ozone fluctuations are attributed to horizontal advection. Fluctuations due to horizontal advection are dominant, as reported in previous studies. The cross-correlation of the effects of vertical and horizontal advection was also evaluated. The correlation is relatively larger at altitudes of 18–23 km and 32–33 km compared to those at other height regions. In contrast to previous studies, horizontal advection by gravity waves seems to play a dominant role in the production of small-scale ozone structures at altitudes of 32–35 km.

scholarly journals Methane as a diagnostic tracer of changes in the Brewer–Dobson circulation of the stratosphere

2015 ◽  
Vol 15 (7) ◽  
pp. 3739-3754 ◽  
Author(s):  
E. E. Remsberg
Keyword(s):  
Time Series ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Wave Activity ◽  
Mixing Ratio ◽  
Use Of Time ◽  
Wave Induced ◽  
Middle Stratosphere

Abstract. This study makes use of time series of methane (CH4) data from the Halogen Occultation Experiment (HALOE) to detect whether there were any statistically significant changes of the Brewer–Dobson circulation (BDC) within the stratosphere during 1992–2005. The HALOE CH4 profiles are in terms of mixing ratio versus pressure altitude and are binned into latitude zones within the Southern Hemisphere and the Northern Hemisphere. Their separate time series are then analyzed using multiple linear regression (MLR) techniques. The CH4 trend terms for the Northern Hemisphere are significant and positive at 10° N from 50 to 7 hPa and larger than the tropospheric CH4 trends of about 3% decade−1 from 20 to 7 hPa. At 60° N the trends are clearly negative from 20 to 7 hPa. Their combined trends indicate an acceleration of the BDC in the middle stratosphere of the Northern Hemisphere during those years, most likely due to changes from the effects of wave activity. No similar significant BDC acceleration is found for the Southern Hemisphere. Trends from HALOE H2O are analyzed for consistency. Their mutual trends with CH4 are anti-correlated qualitatively in the middle and upper stratosphere, where CH4 is chemically oxidized to H2O. Conversely, their mutual trends in the lower stratosphere are dominated by their trends upon entry to the tropical stratosphere. Time series residuals for CH4 in the lower mesosphere also exhibit structures that are anti-correlated in some instances with those of the tracer-like species HCl. Their occasional aperiodic structures indicate the effects of transport following episodic, wintertime wave activity. It is concluded that observed multi-year, zonally averaged distributions of CH4 can be used to diagnose major instances of wave-induced transport in the middle atmosphere and to detect changes in the stratospheric BDC.

scholarly journals Comparison of the inversion algorithms applied to the ozone vertical profile retrieval from SCIAMACHY limb measurements

2007 ◽  
Vol 7 (1) ◽  
pp. 1969-1993
Author(s):  
A. Rozanov ◽  
K.-U. Eichmann ◽  
C. von Savigny ◽  
H. Bovensmann ◽  
J. P. Burrows ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
European Space Agency ◽  
Vertical Profiles ◽  
Upper Troposphere ◽  
Operational Level ◽  
Space Agency ◽  
Lidar Measurements ◽  
Level 1 ◽  
Ground Based Lidar ◽  
Middle Stratosphere

Abstract. This paper is devoted to an intercomparison of ozone vertical profiles retrieved from the measurements of scattered solar radiation performed by the SCIAMACHY instrument in the limb viewing geometry. Three different inversion algorithms including the prototype of the operational Level 1 to 2 processor to be operated by the European Space Agency are considered. The intercomparison was performed for 5 selected orbits of SCIAMACHY showing a good overall agreement of the results in the middle stratosphere, whereas considerable discrepancies were identified in the lower stratosphere and upper troposphere altitude region. Additionally, comparisons with ground-based lidar measurements are shown for selected profiles demonstrating an overall correctness of the retrievals.

Enhanced E. huxleyi carbonate counterpump as a positive feedback to increase deglacial pCO2sw in the Eastern Equatorial Pacific

2021 ◽  
Vol 260 ◽  
pp. 106921
Author(s):  
Chiara Balestrieri ◽  
Patrizia Ziveri ◽  
Michaël Grelaud ◽  
P. Graham Mortyn ◽  
Claudia Agnini
Keyword(s):  
Positive Feedback ◽  
Equatorial Pacific ◽  
Eastern Equatorial Pacific

Ocean Response to Wind Variations, Warm Water Volume, and Simple Models of ENSO in the Low-Frequency Approximation

2010 ◽  
Vol 23 (14) ◽  
pp. 3855-3873 ◽  
Author(s):  
Alexey V. Fedorov
Keyword(s):  
Low Frequency ◽  
Equatorial Pacific ◽  
Warm Water ◽  
Water Volume ◽  
Thermocline Depth ◽  
Phase Lag ◽  
Eastern Equatorial Pacific ◽  
The Pacific ◽  
Warm Water Volume ◽  
Frequency Approximation

Abstract Physical processes that control ENSO are relatively fast. For instance, it takes only several months for a Kelvin wave to cross the Pacific basin (Tk ≈ 2 months), while Rossby waves travel the same distance in about half a year. Compared to such short time scales, the typical periodicity of El Niño is much longer (T ≈ 2–7 yr). Thus, ENSO is fundamentally a low-frequency phenomenon in the context of these faster processes. Here, the author takes advantage of this fact and uses the smallness of the ratio ɛk = Tk/T to expand solutions of the ocean shallow-water equations into power series (the actual parameter of expansion also includes the oceanic damping rate). Using such an expansion, referred to here as the low-frequency approximation, the author relates thermocline depth anomalies to temperature variations in the eastern equatorial Pacific via an explicit integral operator. This allows a simplified formulation of ENSO dynamics based on an integro-differential equation. Within this formulation, the author shows how the interplay between wind stress curl and oceanic damping rates affects 1) the amplitude and periodicity of El Niño and 2) the phase lag between variations in the equatorial warm water volume and SST in the eastern Pacific. A simple analytical expression is derived for the phase lag. Further, applying the low-frequency approximation to the observed variations in SST, the author computes thermocline depth anomalies in the western and eastern equatorial Pacific to show a good agreement with the observed variations in warm water volume. Ultimately, this approach provides a rigorous framework for deriving other simple models of ENSO (the delayed and recharge oscillators), highlights the limitations of such models, and can be easily used for decadal climate variability in the Pacific.

Sign in / Sign up

Export Citation Format

Share Document