scholarly journals CO<sub>2</sub> Surface Variability, from the Stratosphere or Not?

2021 ◽  
Author(s):  
Michael J. Prather

Abstract. Fluctuations in atmospheric CO2 can be measured with great precision and are used to identify human-driven sources as well as natural cycles of ocean and land carbon. One source of variability is the stratosphere, where the influx of aged CO2-depleted air can produce fluctuations at the surface. This process has been speculated a potential source of interannual variability (IAV) in CO2 that might obscure the quantification of other sources of IAV. Given the recent success in demonstrating that the stratospheric influx of N2O- and chlorofluorocarbon-depleted air is a dominant source of their surface IAV in the southern hemisphere, we here apply the same model and measurement analysis to CO2. Using chemistry-transport modeling or scaling of the observed N2O variability, we find that the stratosphere-driven surface variability in CO2 is at most 10 % of the observed IAV and is not an important source. The southern hemisphere stations with multi-decadal CO2 records can provide clues to sources through the phase shifts of the IAV relative to the northern hemisphere.

1996 ◽  
Vol 14 (4) ◽  
pp. 464-467 ◽  
Author(s):  
R. P. Kane

Abstract. The 12-month running means of the surface-to-500 mb precipitable water obtained from analysis of radiosonde data at seven selected locations showed three types of variability viz: (1) quasi-biennial oscillations; these were different in nature at different latitudes and also different from the QBO of the stratospheric tropical zonal winds; (2) decadal effects; these were prominent at middle and high latitudes and (3) linear trends; these were prominent at low latitudes, up trends in the Northern Hemisphere and downtrends in the Southern Hemisphere.


2009 ◽  
Vol 22 (24) ◽  
pp. 6653-6678 ◽  
Author(s):  
Ming Zhao ◽  
Isaac M. Held ◽  
Shian-Jiann Lin ◽  
Gabriel A. Vecchi

Abstract A global atmospheric model with roughly 50-km horizontal grid spacing is used to simulate the interannual variability of tropical cyclones using observed sea surface temperatures (SSTs) as the lower boundary condition. The model’s convective parameterization is based on a closure for shallow convection, with much of the deep convection allowed to occur on resolved scales. Four realizations of the period 1981–2005 are generated. The correlation of yearly Atlantic hurricane counts with observations is greater than 0.8 when the model is averaged over the four realizations, supporting the view that the random part of this annual Atlantic hurricane frequency (the part not predictable given the SSTs) is relatively small (&lt;2 hurricanes per year). Correlations with observations are lower in the east, west, and South Pacific (roughly 0.6, 0.5, and 0.3, respectively) and insignificant in the Indian Ocean. The model trends in Northern Hemisphere basin-wide frequency are consistent with the observed trends in the International Best Track Archive for Climate Stewardship (IBTrACS) database. The model generates an upward trend of hurricane frequency in the Atlantic and downward trends in the east and west Pacific over this time frame. The model produces a negative trend in the Southern Hemisphere that is larger than that in the IBTrACS. The same model is used to simulate the response to the SST anomalies generated by coupled models in the World Climate Research Program Coupled Model Intercomparison Project 3 (CMIP3) archive, using the late-twenty-first century in the A1B scenario. Results are presented for SST anomalies computed by averaging over 18 CMIP3 models and from individual realizations from 3 models. A modest reduction of global and Southern Hemisphere tropical cyclone frequency is obtained in each case, but the results in individual Northern Hemisphere basins differ among the models. The vertical shear in the Atlantic Main Development Region (MDR) and the difference between the MDR SST and the tropical mean SST are well correlated with the model’s Atlantic storm frequency, both for interannual variability and for the intermodel spread in global warming projections.


2008 ◽  
Vol 65 (10) ◽  
pp. 3030-3041 ◽  
Author(s):  
Xun Jiang ◽  
Steven Pawson ◽  
Charles D. Camp ◽  
J. Eric Nielsen ◽  
Run-Lie Shia ◽  
...  

A principal component analysis (PCA) is applied to the Southern Hemisphere (SH) total column ozone following the method established for analyzing the data in the Northern Hemisphere (NH) in a companion paper. The interannual variability (IAV) of extratropical O3 in the SH is characterized by four main modes, which account for 75% of the total variance. The first two leading modes are approximately zonally symmetric and relate to the Southern Hemisphere annular mode and the quasi-biennial oscillation. The third and fourth modes exhibit wavenumber-1 structures. Contrary to the Northern Hemisphere, the third and fourth modes are not related to stationary waves. Similar results are obtained for the 30–100-hPa geopotential thickness. The decreasing O3 trend in the SH is captured in the first mode. The largest trend is at the South Pole, with value ∼−2 Dobson Units (DU) yr−1. Both the spatial pattern and trends in the column ozone are captured by the Goddard Earth Observation System chemistry–climate model (GEOS-CCM) in the SH.


2006 ◽  
Vol 6 (3) ◽  
pp. 5671-5709
Author(s):  
T. Erbertseder ◽  
V. Eyring ◽  
M. Bittner ◽  
M. Dameris ◽  
V. Grewe

Abstract. Dynamics and chemistry of the lower and middle stratosphere are characterized by manifold processes on different scales in time and space. The total column density of ozone, measured by numerous instruments, can be used to trace the resulting variability. In particular, satellite-borne spectrometers allow global observation of the total ozone distribution with proven accuracy and high temporal and spatial resolution. In order to analyse the zonal and hemispherical ozone variability a spectral statistical Harmonic Analysis is applied to multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. In order to demonstrate the capability of the diagnostic for intercomparison studies we apply the hemispheric ozone variability indices to evaluate total ozone fields of the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. Results of a multi-year model simulation representing ''2000" climate conditions with an updated version of E39/C and corresponding total ozone data of TOMS from 1996 to 2004 (Version 8.0) are used. It is quantified to what extent E39/C is able to reproduce the zonal and hemispherical large scale total ozone variations. The different representations of the hemispheric ozone variability indices are discussed. Summarizing the main differences of model and reference observations, we show that both indices, one and two, in E39/C are preferably too high in the Northern Hemisphere and preferably too low in the Southern Hemisphere. In the Northern Hemisphere, where the coincidence is generally better, E39/C produces a too strong planetary wave one activity in winter and spring as well as a too high interannual variability. For the Southern Hemisphere we conclude that model and observations differ significantly during the ozone hole season. In October and November amplitudes of wave number one and two are underestimated. This explains that E39/C exhibits a too stable polar vortex and a too low interannual variability of the ozone hole. Further, a strong negative bias of wave number one amplitudes in the tropics and subtropics from October to December is identified, which may also contribute to the zonal-symmetric polar vortex. The lack of wave two variability in October and November leads to weak vortex elongation and eventually a too late final warming. Contrary, too high wave number two amplitudes in July and August indicate why the polar vortex is formed too late in season by E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust approach to quantify differences in total ozone variability on a monthly mean basis. Therefore, the diagnostic represents a core diagnostic for model intercomparisons within the CCM Validation Activity for WCRP's (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) regarding stratospheric dynamics.


Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 92 ◽  
Author(s):  
Anthony Lupo ◽  
Andrew Jensen ◽  
Igor Mokhov ◽  
Alexander Timazhev ◽  
Timothy Eichler ◽  
...  

A global blocking climatology published by this group for events that occurred during the late 20th century examined a comprehensive list of characteristics that included block intensity (BI). In addition to confirming the results of other published climatologies, they found that Northern Hemisphere (NH) blocking events (1968–1998) were stronger than Southern Hemisphere (SH) blocks and winter events are stronger than summer events in both hemispheres. This work also examined the interannual variability of blocking as related to El Niño and Southern Oscillation (ENSO). Since the late 20th century, there is evidence that the occurrence of blocking has increased globally. A comparison of blocking characteristics since 1998 (1998–2018 NH; 2000–2018 SH) shows that the number of blocking events and their duration have increased significantly in both hemispheres. The blocking BI has decreased by about six percent in the NH, but there was little change in the BI for the SH events. Additionally, there is little or no change in the primary genesis regions of blocking. An examination of variability related to ENSO reveals that the NH interannual-scale variations found in the earlier work has reversed in the early 21st century. This could either be the result of interdecadal variability or a change in the climate. Interdecadal variations are examined as well.


2010 ◽  
Vol 10 (11) ◽  
pp. 25803-25839
Author(s):  
C. D. Nevison ◽  
E. Dlugokencky ◽  
G. Dutton ◽  
J. W. Elkins ◽  
P. Fraser ◽  
...  

Abstract. Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N2O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. These cycles are examined for physical and biogeochemical signals. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. The interannual variability in the seasonal cycle is not always correlated among networks that share common sites. In the Northern Hemisphere, correlations between detrended N2O seasonal minima and polar winter lower stratospheric temperature provide compelling evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N2O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood in order to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N2O monthly means are correlated with polar lower stratospheric temperature in months preceding the N2O minimum, suggesting a coherent stratospheric influence in that hemisphere as well. A decomposition of the N2O seasonal cycle in the extratropical Southern Hemisphere suggests that ventilation of deep ocean water (microbially enriched in N2O) and the stratospheric influx make similar contributions in phasing, and may be difficult to disentangle. In addition, there is a thermal signal in N2O due to seasonal ingassing and outgassing of cooling and warming surface waters that is out of phase and thus competes with the stratospheric and ventilation signals. All the seasonal signals discussed above are subtle and are generally better quantified in high-frequency in situ data than in data from weekly flask samples, especially in the Northern Hemisphere. The importance of abiotic influences (thermal, stratospheric influx, and tropospheric transport) on N2O seasonal cycles suggests that, at many sites, surface N2O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources (e.g., for atmospheric inversions), but may be more powerful if combined with complementary data such as CFC-12 mixing ratios or N2O isotopes.


2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg &amp; Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg &amp; Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).


2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.


2005 ◽  
Vol 23 (8) ◽  
pp. 2803-2811 ◽  
Author(s):  
J. B. Cao ◽  
Z. X. Liu ◽  
J. Y. Yang ◽  
C. X. Yian ◽  
Z. G. Wang ◽  
...  

Abstract. LFEW is a low frequency electromagnetic wave detector mounted on TC-2, which can measure the magnetic fluctuation of low frequency electromagnetic waves. The frequency range is 8 Hz to 10 kHz. LFEW comprises a boom-mounted, three-axis search coil magnetometer, a preamplifier and an electronics box that houses a Digital Spectrum Analyzer. LFEW was calibrated at Chambon-la-Forêt in France. The ground calibration results show that the performance of LFEW is similar to that of STAFF on TC-1. The first results of LFEW show that it works normally on board, and that the AC magnetic interference of the satellite platform is very small. In the plasmasphere, LFEW observed the ion cyclotron waves. During the geomagnetic storm on 8 November 2004, LFEW observed a wave burst associated with the oxygen ion cyclotron waves. This observation shows that during geomagnetic storms, the oxygen ions are very active in the inner magnetosphere. Outside the plasmasphere, LFEW observed the chorus on 3 November 2004. LFEW also observed the plasmaspheric hiss and mid-latitude hiss both in the Southern Hemisphere and Northern Hemisphere on 8 November 2004. The hiss in the Southern Hemisphere may be the reflected waves of the hiss in the Northern Hemisphere.


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