Showing papers by "Paul J. Crutzen published in 1980"

Estimates of gross and net fluxes of carbon between the biosphere and the atmosphere from biomass burning

Abstract: In order to estimate the production of charcoal and the atmospheric emissions of trace gases volatilized by burning we have estimated the global amounts of biomass which are affected by fires. We have roughly calculated annual gross burning rates ranging between about 5 Pg and 9 Pg (1 Pg = 1015 g) of dry matter (2–4 Pg C). In comparison, about 9–17 Pg of above-ground dry matter (4–8 Pg C) is exposed to fires, indicating a worldwide average burning efficiency of about 50%. The production of dead below-ground dry matter varies between 6–9 Pg per year. We have tentatively indicated the possibility of a large production of elemental carbon (0.5–1.7 Pg C/yr) due to the incomplete combustion of biomass to charcoal. This provides a sink for atmospheric CO2, which would have been particularly important during the past centuries. From meager statistical information and often ill-documented statements in the literature, it is extremely difficult to calculate the net carbon release rates to the atmosphere from the biomass changes which take place, especially in the tropics. All together, we calculate an overall effect lof the biosphere on the atmospheric carbon dioxide budget which may range between the possibilities of a net uptake or a net release of about 2 Pg C/yr. The release of CO2 to the atmosphere by deforestation projects may well be balanced by reforestation and by the production of charcoal. Better information is needed, however, to make these estimates more reliable.

Latitudinal distributions of CO and CH4 over the Pacific

Abstract: Measurements on Gametag (Global Atmospheric Measurements Experiment of Tropospheric Aerosols and Gases) in April and May 1978 indicate volume mixing ratios of CH4 of 1.62 ppmv south of the intertropical convergence zone and 1.72 ppmv north of 20°N. For CO south of 10°S, the CO volume mixing ratios were rather constant and equal to 57 ppbv. Poleward of 30°N in the northern hemisphere we measured average mixing ratios of 175 ppbv. Both for CO and for CH4 a gradual transition from lower southern hemispheric to higher northern hemispheric values were observed between 10°S and 20°N. The uncertainties in our measurements are 15% for CO and 3% for CH4. By comparing our observations with earlier ones (Seiler, 1974; Ehhalt, 1978), we can not detect any changes in the atmospheric abundances of CO and CH4 from 1972 to 1978 outside the uncertainty limits of the measurements.

Scientific objectives of the Solar Mesosphere Explorer mission

Abstract: The paper describes the NASA Solar Mesosphere Explorer mission which will study mesospheric ozone and the processes which form and destroy it, measure the ozone density and its altitude distribution from 30 to 80 km, monitor incoming solar UV radiation, and provide a rigorous test of the photochemical equilibrium theory of the mesospheric oxygen-hydrogen system. Five instruments will be carried on the polar-orbiting spacecraft: UV ozone, IR airglow, and visible NO2 programmable Ebert-Fastie spectrometers, a four-channel IR radiometer, and a solar UV spectrometer. Atmospheric measurements will be made of the mesospheric and stratospheric ozone density distribution, water vapor density distribution, temperature profile, ozone photolysis rate, and NO2 density distribution. In addition, the solar UV monitor will measure both the 0.2-0.31 micron spectral region and the Lyman-alpha (0.1216 micron) contribution to the solar irradiance.

First measurements of total chlorine and bromine in the lower stratosphere

Abstract: A total halogen collection system employing ultra-pure activated charcoal traps has been developed for use in the stratosphere aboard aircraft and balloon sampling platforms Neutron activation techniques for low-level chlorine, bromine, and iodine analysis within the activated charcoal sampling matrix were developed Initial results from six aircraft flights and one balloon mission in the lower stratosphere are presented for latitudes ranging from 16/sup 0/N to 67/sup 0/N Little variability was observed in twelve total, gaseous and particulate chlorine (Cl/sub tot/) determinations as a function of latitude at 20 km with values ranging between 27 +- 9 ppbV and 32 +- 7 ppbV Five total bromine (Br/sub tot/) values showed substantial variability ranging from 7 +- 4 pptV to 40 +- 11 pptV No iodine was observed in any samples but a calculated I/sub tot/ upper limit of < 3 pptV was determined