Boundary layer turbulent transport and production/destruction of ozone during summertime smog episodes over the Swiss plateau

Turbulent fluxes of sensible and latent heat and ozone were measured aboard a German Aerospace Research Establishment motorglider over the Swiss Plateau during the first field experiment of the Swiss air pollution experiment POLLUMET. In the lower part of the boundary layer, the ozone fluxes are negative (downward) throughout the day as a result of deposition and photochemical destruction at the surface. In the upper part of the boundary layer, the ozone fluxes tend to be negative until mid-afternoon and then become positive. The change in sign occurs after the ozone concentration in the boundary layer exceeds that in the reservoir above the inversion. Downdrafts bringing air parcels with ozone deficits across the inversion then become major contributors to the flux. The positive fluxes at upper levels result in an increase in flux divergence in mid-afternoon that is balanced by a relatively large source term in the ozone concentration budget. (orig.)Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

MEASUREMENT OF RESONANCE PRODUCTIONS IN THE REACTIONS gamma gamma ---> pi0 pi0 AND gamma gamma ---> pi0 eta

Resonance production in the γγ reactionse + e −→e + e + e − π 0 π 0 ande + e − π 0 η has been studied with the JADE detector at PETRA. The decay widths into γγ of thef 2(1270),a 0(980) anda 2(1320) were measured to be Γγγ(f2(1270))=3.19±0.09+0.22−0.38 Kev,Γ λλ(a 0(980))=0.28±0.04±0.10 KeV/BR(a 0(980)→π 0 η) andΓ λλ (a 2(1320))=1.01±0.14±0.22KeV. For thef 0(975) andf 4(2050) upper limits of the widths were obtained,Γ λλ (f 0(975))<0.6 KeV, andΓ λλ(f 4(2050))<1.1 KeV, both at the 95% C.L. Assuming that the spin 0 background under thef 2(1270) is small, thef 2(1270) was found to be produced exclusively in a helicity 2 state. The helicity 0 contribution is <15% at the 95% C.L. The cross section forλλ→π 0 π 0 in the mass range 2.0–3.5 GeV/c2 was measured for the first time. Since the cross section forλλ→π + π − is a factor ∼2 larger, ππ production in this range can be interpreted as taking place via isospin 0 production