Analyzing Atmospheric Circulation Patterns Using Mass Fluxes Calculated from Weather Balloon Measurements: North Atlantic Region as a Case Study

Abstract

In recent decades, efforts to investigate atmospheric circulation patterns have predominantly relied on either semi-empirical datasets (i.e., reanalyses) or modeled output (i.e., global climate models, GCMs). While both approaches can provide important insights, there is a need for more empirical data to supplement these approaches. In this paper, we demonstrate how the application of relatively simple calculations to the basic measurements from a standard weather balloon radiosonde can provide a vertical profile of the horizontal atmospheric mass fluxes. These mass fluxes can be resolved into their meridional (north/south) and zonal (east/west) components. This provides a new useful empirical tool for analyzing atmospheric circulations. As a case study, we analyze the results for a selected five stations along a fairly constant meridian in the North Atlantic sector from 2015–2019. For each station, we find the atmospheric mass flux profiles from the lower troposphere to mid-stratosphere are surprisingly coherent, suggesting stronger interconnection between the troposphere and stratosphere than previously thought. Although our five stations span a region nominally covered by the classical polar, Ferrel and Hadley meridional circulation cells, the results are inconsistent with those expected for polar and Ferrel cells and only partially consistent with that of a Hadley cell. However, the region is marked by very strong prevailing westerly (west to east) mass fluxes for most of the atmosphere except for the equatorial surface easterlies (“trade winds”). We suggest that the extension of the techniques of this case study to other stations and time periods could improve our understanding of atmospheric circulation patterns and their time variations.

Comparing Different Tropopause Estimates From High‐Resolution Ozonesondes

“…For the other new tropopause definition, we use a metric which does not appear to have been considered before—other than in a series of working papers in 2014 by two of us (Connolly & Connolly, 2014a, 2014b, 2014c). That is, the use of molar density—a concept that should be relatively familiar to chemists, but does not appear to have received much attention in the analysis of weather balloons until now (Connolly et al., 2021).…”

“…More recently, Connolly et al. (2021) have shown that molar densities can also be converted into atmospheric mass fluxes when combined with the accompanying horizontal wind measurements. However, until now, the relevance of these relatively simple molar density calculations for studying the atmosphere appears to have been overlooked by the atmospheric science community.…”

“…The molar density, D, at each point is calculated from the corresponding pressure and temperature measurements, following the approach described by Connolly et al. (2021). That is, D = P/RT, where R = 8.314 J K −1 mol −1 is the ideal gas constant, P is the atmospheric pressure (in Pa units) and T is the temperature (in K units).…”

“…Indeed, others have already noted that the troposphere/stratosphere transitions are associated with changes in wind velocities (T. Birner, 2006; Fueglistaler et al., 2009). The data from these ozonesondes would also be suitable for investigating the horizontal mass fluxes (Connolly et al., 2021). However, this more detailed analysis is beyond the scope of this study.…”

“…Two of us (MC and RC) have described in detail the surprising utility of molar density calculations for analyzing weather balloon sondes in a series of working papers in 2014 (Connolly & Connolly, 2014a, 2014b, 2014c. More recently, Connolly et al (2021) have shown that molar densities can also be converted into atmospheric mass fluxes when combined with the accompanying horizontal wind measurements. However, until now, the relevance of these relatively simple molar density calculations for studying the atmosphere appears to have been overlooked by the atmospheric science community.…”