¹⁰Be/⁷Be tracer of atmospheric transport and stratosphere‐troposphere exchange

Abstract

[1] The 10 Be/ 7 Be ratio is a sensitive tracer of atmospheric transport and stratospheretroposphere exchange (STE). Data from five NASA aircraft field missions (PEM: West A and B, Tropics A; SONEX; and SUCCESS) have been assembled to produce the largest data set of 10 Be, 7 Be, and their ratio collected to date (>300 samples). Ratios near 0.60 are indicative of tropospheric air with little stratospheric influence, while higher ratios are found in stratospheric air. Samples from the lower stratosphere were all collected within 2.5 km of the tropopause and had ratios >1.27. Of these lower stratosphere samples only 16% had ratios in excess of 3.0, suggesting that higher ratio air resides away from the tropopause. Seasonality observed in the 10 Be/ 7 Be ratios results from the downwelling of air with elevated ratios from higher in the stratosphere in the spring and summer (midlatitudes) and from the decay of 7 Be during descent in the winter polar vortex (high latitudes). Our results illustrate the complexity of STE and some of the mechanisms through which it occurs, including tropopause folding, mixing associated with subtropical jets, and the effect of synoptic systems such as hurricanes and northeasters. The 10 Be/ 7 Be ratio provides important information beyond that which can be derived from studies that rely on chemical mixing ratios alone.INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0368 Atmospheric Composition and Structure: Troposphereconstituent transport and chemistry; 3362 Meteorology and Atmospheric Dynamics: Stratosphere/troposphere interactions; KEYWORDS: Aerosols, radioisotopes, beryllium, stratosphere-troposphere exchange Citation: Jordan, C. E., J. E. Dibb, and R. C. Finkel, 10 Be/ 7 Be tracer of atmospheric transport and stratosphere-troposphere exchange,

Forecast, observation and modelling of a deep stratospheric intrusion event over Europe

“…The ratios of 10 Be/ 7 Be, which is a stratospheric tracer not affected by washout, remain rather constant on 20, 21 and 22 June, ranging from 1.71 to 1.90 (3rd quartile = 2.1 in Table 2). Jordan et al (2003), using aircraft samples in both the stratosphere and troposphere reported the absence of ratios <1.27 in the lowermost stratosphere indicating that ratios observed in the troposphere, nearer their production ratio of 0.60, are characteristic of tropospheric air with minimal stratospheric influence. So the ratio measurements at Zugspitze during this case study, even though they are not among the highest recorded during 2000 and 2001 imply stratospheric influence.…”

“…In addition, the ratio of 10 Be/ 7 Be can also be used to trace stratospheric air, like 10 Be and 7 Be independently because the ratio values in the stratosphere (especially in the lower stratosphere) are much higher than in the troposphere due to the much longer half-life of 10 Be (1.5110 6 yr) compared to 7 Be (53.12 d) and the relatively long residence time of stratospheric air masses ranging from months to years (Raisbeck et al, 1981). Recently, three case studies based on aircraft samples showed that 10 Be/ 7 Be ratios, when determined in the context of other chemical constituents, can provide insight into the various mechanisms of STT (Jordan et al, 2003). However, in contrast to 7 Be, which is measured regularly with high-resolution gamma-ray spectrometry at Alpine peak stations, regular 10 Be measurements are scarce, especially in Europe, because its detection requires accelerator mass spectrometry, which is an expensive method for continuous monitoring.…”

“…Although the stratospheric tracers O 3 , H 2 O, PV and 7 Be have been widely used so far for both climatological and case studies of STT, there are only very few studies, which are mainly climatological, making use of measurements of the cosmogenic radionuclide 10 Be and the ratio 10 Be/ 7 Be (Dibb et al, 1994;Jordan et al, 2003). The cosmogenic radionuclides 7 Be and 10 Be are produced through spallation reactions mainly in the stratosphere but they cannot be considered as ideal stratospheric tracers because they attach to aerosols and hence their tropospheric lifetime is significantly controlled by wet scavenging processes.…”

Modeling cosmogenic radionuclides &lt;sup&gt;10&lt;/sup&gt;Be and &lt;sup&gt;7&lt;/sup&gt;Be during the Maunder Minimum using the ECHAM5-HAM General Circulation Model

“…6 the modeled 10 Be and 7 Be concentrations in air are compared with observations from aircraft measurements (Dibb et al, 1997;Jordan et al, 2003;Winiger et al, 1976) from the troposphere and lower stratosphere (altitudes between 0 and 14 km). All observations are from the Northern Hemisphere, representing different longitudes and time periods.…”

10Be/7Be implies the contribution of stratosphere-troposphere transport to the winter-spring surface O3 variation observed on the Tibetan Plateau

“…However, as a natural stratospheric tracer, 10 Be/ 7 Be effectively indicates the contribution of Stratosphere-Troposphere Transport (STT) to surface-level O 3 variations as observed in the European Alps and Arctic regions [2,3]. Jordan et al [4] reported latitudinal distribution of 10 Be/ 7 Be values in the upper troposphere and lower stratosphere over several regions through analysis of extensive aircraft aerosol samples. However, publications of at-mospheric 10 Be measurements are still limited because of the complexities in 10 Be target preparation and 10 Be detection by Accelerator Mass Spectrometry (AMS).…”