scholarly journals Further Evidence of Changing Stability of the Atmosphere

Radiocarbon ◽  
1995 ◽  
Vol 37 (3) ◽  
pp. 961-962 ◽  
Author(s):  
Sylvius Hartwig
Keyword(s):  
Seasonal Pattern ◽  
Ground Level ◽  
Ozone Layer ◽  
Heat Sources ◽  
Exchange Processes ◽  
Long Term Measurement ◽  
Ground Level Air

In a recent paper (Hartwig, ms.) I have shown that it is possible to understand and discuss the changing Austausch (i.e., exchange of air parcels between different atmospheric layers) between the stratosphere and troposphere by means of long-term measurement of series of spallation products. It is well known (Friend 1961; Müh et al. 1966; Hartwig et al. 1969) that there is a seasonal pattern in the 7Be concentration of ground-level air with a maximum during May–June. This maximum is caused by enhanced exchange processes between the atmospheric compartments of the stratosphere and troposphere during this interval. Generally, those exchange processes are a consequence of stability and dynamics of the atmospheric compartments, which themselves result from, among other factors, the distribution of the heat sources in those compartments, namely the ground and the ozone layer.

Langjährige Be7 -Bodenluftmessungen lassen Änderung des atmosphärischen Austauschverhaltens während der letzten Jahrzehnte vermuten

1996 ◽  
Vol 51 (10-11) ◽  
pp. 1139-1143 ◽  
Author(s):  
S. Hartwig
Keyword(s):  
Exchange Process ◽  
Ground Level ◽  
Eddy Diffusivity ◽  
Source Distribution ◽  
Air Concentration ◽  
Minimum Concentration ◽  
Exchange Processes ◽  
Yearly Maximum ◽  
Heat Source Distribution ◽  
Ground Level Air

Abstract An analysis covering three decades (1964-1994) of monthly Be7 ground-level-air concentration measurements at Braunschweig shows a systematic trend of the data. This trend is related to the yearly maximum/minimum concentration ratio. The observation may be due to a continuous mitigation of exchange processes between stratosphere and troposphere. This finding is commensurate with the hypothesis that, due to the growing concentration of anthropogenic infrared active gases, the heat source distribution in the stratosphere and consequently the eddy diffusivity and exchange process between stratosphere and troposphere are altered. This results in a shorter irradiation period of stratospheric air portions by cosmic rays and consequently can lower the concentration of isotopes of stratospheric origin in ground level air.

Strontium-90, strontium-89, plutonium-239, and plutonium-238 concentrations in ground-level air, 1964-1969

1970 ◽  
Vol 4 (7) ◽  
pp. 598-602 ◽  
Author(s):  
Bernard Shleien ◽  
Joseph A. Cochran ◽  
Paul J. Magno
Keyword(s):  
Ground Level ◽  
Strontium 90 ◽  
Ground Level Air

scholarly journals Simultaneous generalized and low-layer SCIDAR turbulence profiles at san pedro mártir observatory

2019 ◽  
Vol 490 (1) ◽  
pp. 1397-1405 ◽  
Author(s):  
R Avila ◽  
O Valdés-Hernández ◽  
L J Sánchez ◽  
I Cruz-González ◽  
J L Avilés ◽  
...  
Keyword(s):  
High Altitude ◽  
Wind Direction ◽  
Close Agreement ◽  
Baja California ◽  
Ground Level ◽  
Combined Effect ◽  
Moderate Altitude ◽  
San Pedro ◽  
Simultaneous Measurements

ABSTRACT We present optical turbulence profiles obtained with a Generalized SCIDAR (G-SCIDAR) and a low-layer SCIDAR (LOLAS) at the Observatorio Astronómico Nacional in San Pedro Mártir (OAN-SPM), Baja California, Mexico, during three observing campaigns in 2013, 2014, and 2015. The G-SCIDAR delivers profiles with moderate altitude-resolution (a few hundred metres) along the entire turbulent section of the atmosphere, while the LOLAS gives high altitude resolution (on the order of tens of metres) but only within the first few hundred metres. Simultaneous measurements were obtained on 2014 and allowed us to characterize in detail the combined effect of the local orography and wind direction on the turbulence distribution close to the ground. At the beginning of several nights, the LOLAS profiles show that turbulence peaks between 25 and 50 m above the ground, not at ground level as was expected. The G-SCIDAR profiles exhibit a peak within the first kilometre. In 55 per cent and 36 per cent of the nights stable layers are detected between 10 and 15 km and at 3 km, respectively. This distribution is consistent with the results obtained with a G-SCIDAR in 1997 and 2000 observing campaigns. Statistics computed with the 7891 profiles that have been measured at the OAN-SPM with a G-SCIDAR in 1997, 2000, 2014, and 2015 campaigns are presented. The seeing values calculated with each of those profiles have a median of 0.79, first and third quartiles of 0.51 and 1.08 arcsec, which are in close agreement with other long term seeing monitoring performed at the OAN-SPM.

Continuous automatic measurement of rhythms in fungal respiration using a gas chromatograph

1973 ◽  
Vol 51 (4) ◽  
pp. 701-710 ◽  
Author(s):  
Roger S. Smith
Keyword(s):  
Carbon Dioxide ◽  
Agar Medium ◽  
Quantitative Measure ◽  
Automatic Measurement ◽  
Carbon Dioxide Production ◽  
Chromatographic Technique ◽  
Gas Chromatograph ◽  
Growth Chambers ◽  
Long Term Measurement

The long-term measurement of aerobic fungal respiration, both on an agar medium and on wood blocks, was possible using a gas-chromatographic technique for the detection of the carbon dioxide. This method was fully automated to analyze gas samples sequentially from eight or more growth chambers, after variable but determined time periods. It provided a precise quantitative measure of the respired carbon dioxide, presented both in the form of punched computer tape and normal printed teleprinter output. This apparatus worked continuously for several years without serious breakdown.The fungi Lentinus lepideus, Lenzites trabea, Poria monticola, and several strains of Coniophora puteana all showed a rhythm in their respiration which was not controlled by temperature or light. The magnitude and frequency of the rhythmical peaks in carbon dioxide production varied between fungi and, although there was considerable variation between different isolates of the same species, the separation of these species of fungi based on their different patterns of respiration was possible.

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