The total solar eclipse of 11 August 1999 over Central Europe was also visible in Baden-Wuerttemberg, a state in southwest Germany. To investigate the impact of the total solar eclipse on the lower planetary boundary layer, meteorological and air quality data extracted from routine measurements at six sites in Baden-Wuerttemberg were examined. The meteorological data were recorded at the Plittersdorf meteorological station (in the path of totality of the total solar eclipse) and at the Forestmeteorological Site Hartheim (outside the path of totality of the total solar eclipse). The air quality data were obtained from four of cial air quality monitoring stations located at Freudenstadt, Karlsruhe-West, Rastatt and Welzheimer Wald, all of which lie within the path of totality of the total solar eclipse. Due to cloudiness, weather conditions on 11 August 1999 were not optimal in southwest Germany. However, the transient reduction (followed by a rise) induced by the total solar eclipse on meteorological variables including global solar radiation, upward longwave radiation, net radiation, air temperature, horizontal wind speed, elevation angle of the three-dimensional wind vector as well as turbulent sensible and latent heat uxes was quite obvious. Despite unfavourable weather conditions, half-hourly mean values of ozone routinely measured at the above-mentioned standard of cial air quality monitoring stations showed a varying decline up to 27% at the urban station Rastatt and 37% at the background station Welzheimer Wald. This decline was owing mainly to the fall in global radiation during the total solar eclipse. However, additional in uences by advection and deposition can not be precluded. Zusammenfassung Die totale Sonnen nsternis am 11. August 1999über Mitteleuropa konnte auch im Südwesten von Deutschland im Bundesland Baden-Württemberg beobachtet werden. Ihre Auswirkung auf die untere planetare Grenzschicht wurdeüber Daten untersucht, die routinemäßig an der meteorologischen Station Plittersdorf in der Kernzone der Sonnen nsternis und an der Forstmeteorologischen Messstelle Hartheim außerhalb der Kernzone der Sonnen nsternis sowie an den vier amtlichen Luftmessstationen Freudenstadt, Karlsruhe-West, Rastatt und Welzheimer Wald innerhalb der Kernzone der Sonnen nsternis erhoben werden. Obwohl am 11. August 1999 in Südwestdeutschland kein Strahlungswetter herrschte, ließen sich als Folge der Sonnen nsternis die Abnahme und anschließende Zunahme von Globalstrahlung, langwelliger Ausstrahlung der Erdober äche, Strahlungsbilanz, Lufttemperatur, horizontaler Windgeschwindigkeit , Elevationswinkel des dreidimensionalen Windvektors sowie turbulenter Ströme fühlbarer und latenter Wärme erkennen. Trotz ungünstiger Wetterverhältnisse zeigte sich auch bei den Halbstundenmittelwerten von Ozon, die an amtlichen Luftqualitätsmessstellen in der Kernzone der Sonnen nsternis in Baden-Württemberg routinemäßig gemessen werden, häu g eine Reduktion. Sie betrug an der Stadtstation Rastatt bis zu ca. 27% und an der Hintergrundstation...
No abstract
The oxidant concentration in the air over the San Francisco Bay Area and the Pacific Ocean was measured up to an altitude of 2500 m and the observed distribution in the vertical and horizontal has been related to the characteristics and behavior of the west coast temperature inversion. Vertical time sections at fixed points and vertical cross sections were constructed of oxidant concentration, temperature, humidity and winds measured from aircraft and radar. The oxidant concentration in polluted air is strongly dependent on the destruction rate. The mean destruction rate within the surface layer depends directly on the intensity of eddy mixing and inversely on the square of the depth of the vertical mixing. Thus, the existence of a temperature inversion does not necessarily lead to a high concentration of oxidants, since the destruction rate may be high in a shallow mixing layer. The highest oxidant concentration was observed almost invariably at the edges of the west coast marine inversion, where pollutants are available for ozone production and the mixing layer is deep. Explanations are offered for the maxima of ozone that often occur above the inversion base. Distribution patterns of oxidants clearly depict the waving of the inversion layer.
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