Superrotation in Terrestrial Atmospheres

Atmospheric superrotation with prograde equatorial winds and an equatorial angular momentum maximum is ubiquitous in planetary atmospheres. It is clear that eddy fluxes of angular momentum toward the equator are necessary to generate it. But under what conditions superrotation arises has remained unclear. This paper presents simulations and a scaling theory that establish conditions under which superrotation occurs in terrestrial atmospheres. Whether superrotation arises depends on the relative importance of factors that favor or disfavor superrotation. Convection preferentially generates Rossby waves near the equator, where the Rossby number is O(1). Since the Rossby waves transport angular momentum toward their source regions, this favors superrotation. Meridional temperature gradients preferentially lead to baroclinic instability and wave generation away from the equator. Eddy transport of angular momentum toward the baroclinic source region implies transport out of low latitudes, which disfavors superrotation. Simulations with an idealized GCM show that superrotation tends to arise when the equatorial convective generation of wave activity and its associated eddy angular momentum flux convergence exceed the baroclinic eddy angular momentum flux divergence. Convective and baroclinic wave activity generation is related through scaling arguments to mean-flow properties, such as planetary rotation rates and meridional temperature gradients. The scaling arguments show, for example, that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low, as they are, for example, on Venus. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global warming simulations

Formaldehyde around 3.5 and 5.7-µm: measurement and calculation of broadening coefficients

International audienceSelf- and N2-broadening coefficients of H2CO have been retrieved in both the 3.5 and 5.7-μm spectral regions. These coefficients have been measured in FT spectra for transitions with various J (from 0 to 25) and K values (from 0 to 10), showing a clear dependence with both rotational quantum numbers J and K. First, an empirical model is presented to reproduce the rotational dependence of the measured self- and N2-broadening coefficients. Then, calculations of N2-broadening of H2CO were made for some for 3296 2 transitions using the semi-classical Robert-Bonamy formalism. These calculations have been done for various temperatures in order to obtain the temperature dependence of the line widths. Finally, self- and N2-broadening coefficients, as well as temperature dependence of the N2-widths has been generated to complete the whole HITRAN 2008 version of formaldehyde (available as supplementary materials)

Is proximity to a food retail store associated with diet and BMI in Glasgow, Scotland?

<p><b>Background:</b> Access to healthy food is often seen as a potentially important contributor to diet. Policy documents in many countries suggest that variations in access contribute to inequalities in diet and in health. Some studies, mostly in the USA, have found that proximity to food stores is associated with dietary patterns, body weight and socio-economic differences in diet and obesity, whilst others have found no such relationships. We aim to investigate whether proximity to food retail stores is associated with dietary patterns or Body Mass Index in Glasgow, a large city in the UK.</p> <p><b>Methods:</b> We mapped data from a 'Health and Well-Being Survey' (n = 991), and a list of food stores (n = 741) in Glasgow City, using ArcGIS, and undertook network analysis to find the distance from respondents' home addresses to the nearest fruit and vegetable store, small general store, and supermarket.</p> <p><b>Results:</b> We found few statistically significant associations between proximity to food retail outlets and diet or obesity, for unadjusted or adjusted models, or when stratifying by gender, car ownership or employment.</p> <p><b>Conclusions:</b> The findings suggest that in urban settings in the UK the distribution of retail food stores may not be a major influence on diet and weight, possibly because most urban residents have reasonable access to food stores.</p&gt

Area-level socioeconomic characteristics and incidence of metabolic syndrome: a prospective cohort study

BACKGROUND The evidence linking socioeconomic environments and metabolic syndrome (MetS) has primarily been based on cross-sectional studies. This study prospectively examined the relationships between area-level socioeconomic position (SEP) and the incidence of MetS. METHODS A prospective cohort study design was employed involving 1,877 men and women aged 18+ living in metropolitan Adelaide, Australia, all free of MetS at baseline. Area-level SEP measures, derived from Census data, included proportion of residents completing a university education, and median household weekly income. MetS, defined according to International Diabetes Federation, was ascertained after an average of 3.6 years follow up. Associations between each area-level SEP measure and incident MetS were examined by Poisson regression Generalised Estimating Equations models. Interaction between area- and individual-level SEP variables was also tested. RESULTS A total of 156 men (18.7%) and 153 women (13.1%) developed MetS. Each percentage increase in the proportion of residents with a university education corresponded to a 2% lower risk of developing MetS (age and sex-adjusted incidence risk ratio (RR) = 0.98; 95% confidence interval (CI) =0.97-0.99). This association persisted after adjustment for individual-level income, education, and health behaviours. There was no significant association between area-level income and incident MetS overall. For the high income participants, however, a one standard deviation increase in median household weekly income was associated with a 29% higher risk of developing MetS (Adjusted RR = 1.29; 95%CI = 1.04-1.60). CONCLUSIONS While area-level education was independently and inversely associated with the risk of developing MetS, the association between area-level income and the MetS incidence was modified by individual-level income.Anh D Ngo, Catherine Paquet, Natasha J Howard, Neil T Coffee, Robert Adams, Anne Taylor and Mark Danie

Observations and Modeling of Tropical Planetary Atmospheres

This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn’s atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn’s subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find that these subtropical bands require very low ammonia relative humidity below the ammonia cloud layer in order to achieve the high brightness temperatures observed. We suggest that these bright subtropical bands represent dry zones created by a meridionally overturning circulation. Second, I use a dry atmospheric general circulation model to study equatorial superrotation in terrestrial atmospheres. A wide range of atmospheres are simulated by varying three parameters: the pole-equator radiative equilibrium temperature contrast, the convective lapse rate, and the planetary rotation rate. A scaling theory is developed that establishes conditions under which superrotation occurs in terrestrial atmospheres. The scaling arguments show that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global-warming simulations. Third, I use a moist slab-ocean general circulation model to study the impact of a zonally-symmetric continent on the distribution of monsoonal precipitation. I show that adding a hemispheric asymmetry in surface heat capacity is sufficient to cause symmetry breaking in both the spatial and temporal distribution of precipitation. This spatial symmetry breaking can be understood from a large-scale energetic perspective, while the temporal symmetry breaking requires consideration of the dynamical response to the heat capacity asymmetry and the seasonal cycle of insolation. Interestingly, the idealized monsoonal precipitation bears resemblance to precipitation in the Indian monsoon sector, suggesting that this work may provide insight into the causes of the temporally asymmetric distribution of precipitation over southeast Asia.</p

Semiclassical calculations of half-widths and line shifts for transitions in the 30012←00001 and 30013←00001 bands of CO<SUB>2</SUB>. III: Self collisions

International audienceThis paper is the third in a series devoted to accurate semi-empirical calculations of pressure-broadened half-widths, pressure-induced line shifts, and the temperature dependence of the half-widths of carbon dioxide. In this work complex Robert-Bonamy (CRB) calculations were made for transitions in two of the Fermi-tetrad bands for self-collisions, i.e. the CO2-CO2 system. The intermolecular potential (IP) was adjusted to match measurements of the half-width, its temperature dependence, and the line shift. It is shown that small changes in the parameters describing the IP lead to noticeable changes in the line shape parameters and that it is possible to find a set of IP parameters, which, when used in the CRB formalism, yield half-widths, their temperature dependence, and line shifts in excellent agreement with measurement. This work demonstrates that this agreement can be obtained if the atom-atom potential is expanded to high order and rank (here 20 4 4), the real and imaginary (S1 and Im(S2)) components are retained, and the determination of the trajectories is made by solving Hamilton's equations. It was found that the temperature dependence of the half-width is sensitive to the range of temperatures used in the fit and that the vibrational dependence of the line shape parameters for these two bands is very small. Databases of the half-width, its temperature dependence, and the line shift for the atmospheres of Venus (296-700 K fit range for the temperature exponents of the half-widths) and Mars (125-296 K fit range for the temperature exponents of the half-widths) are provided. The calculations are compared with the measured data for the bands under study

Semiclassical calculations of half-widths and line shifts for transitions in the 30012←00001 and 30013←00001 bands of CO<SUB>2</SUB> II: Collisions with O<SUB>2</SUB> and air

International audienceThe complex Robert-Bonamy (CRB) formalism was used to calculate the half-width, its temperature dependence, and the line shift for CO2 for transitions in the 30012←00001 and 30013←00001 bands with O2 as the perturbing gas. The calculations were done for rotational quantum numbers from J=0 to J=120 with no ad hoc scaling of the line shape equations. The intermolecular potential parameters are adjusted on accurate experimental measurements of the half-widths, its temperature dependence, and the pressure-induced line shifts so that a single intermolecular potential reproduces all three parameters. Using the results of this work and previous results for N2-broadening, air-broadening line shape parameters were also determined. The comparison of the CRB calculations with the experimental data available in the literature for the three line shape coefficients demonstrates the quality of the present calculations for the both bands under study

Semiclassical calculations of half-widths and line shifts for transitions in the 30012←00001 and 30013←00001 bands of CO<SUB>2</SUB>, I: Collisions with N<SUB>2</SUB>

International audienceCalculations of the half-width, its temperature dependence, and the line shift are made for the rotational states J=0-120 for two of the Fermi-tetrad bands (30012←00001 and 30013←00001) of CO2 perturbed by N2. The calculations employ the semi-classical complex Robert-Bonamy method with no ad hoc scaling, J-dependent or otherwise, and an intermolecular potential (IP) comprised of an electrostatic part, an atom-atom part, and an isotropic London dispersion part. The averaging over the impact parameter b and relative speed v are explicitly carried out. Many interesting features about CO2 as the radiating molecule are elucidated. Effects of the trajectory model, the order of the expansion of the atom-atom component of the potential, and the inclusion of the imaginary terms are studied. It is shown that the results are very sensitive to the intermolecular potential. The final IP parameters give results that demonstrate excellent agreement with measurement for the three line shape parameters studied in this work

Corrigendum to "Measurement and computations for temperature dependences of self-broadened carbon dioxide transitions in the 30012-00001 and 30013-00001 bands" [J. Quant. Spectrosc. Radiat. Transf. 111 (9) (2010) 1065-1079] doi: 10.1016/j.jqsrt.2010.01.003

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