[1] The photodissociation of acetone has been studied over the wavelength (l) range 279 -327.5 nm as a function of temperature (T) and pressure (p) using a spectroscopic method to monitor the acetyl (CH 3 CO) radical fragment. Above 310 nm the quantum yield (QY) is substantially smaller than previous measurements, and decreases with T. The QYs for production of CH 3 CO + CH 3 and CH 3 + CH 3 + CO have been parameterised as a function of l, p and T and used to calculate the altitude dependence of the photolysis frequency. In the upper troposphere (UT) the acetone photolysis lifetime is a factor of 2.5-10 longer, dependent upon latitude and season, than if the previously recommended QYs are used.

[1] Can airborne observations from infrequent flights be used to infer the budget of ozone in the upper troposphere with any degree of certainty or representativeness? Fluctuations in ozone mixing ratio observed along flights are dominated by flying between air masses with distinct origins, rather than the recent chemical transformation that has occurred within those air masses. Reverse domain filling trajectories arriving on a high-resolution three-dimensional grid (RDF3D) can simulate air mass structure accurately by coloring arrival grid points with specific humidity (q) from the origin of each trajectory. Typical displacement errors in tracer filaments are only about 30 km, but the associated phase errors greatly reduce the correlations between airborne observations of long-lived chemicals and their model simulations. However, the comparison can be vastly improved if equivalent potential temperature (q e ) and specific humidity are used as coordinates to label air masses. Both properties are approximately conserved following unsaturated air and serve as good markers of air masses even if the air is saturated or mixing takes place. Ozone simulations from a Lagrangian model are evaluated against observations in thermodynamic coordinates, factoring out many of the transport phase errors. The proportion of the atmosphere occupied by different chemical air masses is estimated by using RDF3D trajectories to simulate the distributions of q and q e and then assuming that chemical composition is homogeneous within air masses, each with characteristic (q, q e ). Mass density in thermodynamic coordinates is used to weight the modeled ozone transformation and error in concentration (calculated along flight tracks) to estimate photochemically produced ozone throughout a volume encompassing the flights.

[1] The vertical distribution of 21 C 2 -C 7 nonmethane hydrocarbons (NMHCs) has been determined in planetary boundary layer (PBL) and free tropospheric (FT) air over central Europe under a range of meteorological conditions. High-frequency whole air sampling was conducted on board the U.K. Meteorological Office C-130 Hercules aircraft during the European Export of Precursors and Ozone by Long-Range Transport (EXPORT) experiment in August 2000. When vertical transport by large-scale flow or convection was weak, the expected large concentration gradient between the PBL and FT was observed for all short and medium lifetime hydrocarbons (e.g., average iso-butane, PBL 100 pptV, FT 6 pptV). During periods of strong convective activity associated with the passage of a cold front, a rapid uplift of reactive carbon from the boundary layer to the mid free troposphere was observed. Using changing ratios of hydrocarbons with different atmospheric lifetimes, a timescale for transport during this event was determined. Hydrocarbon lifetime measurements suggest that in certain regions of the system, it is convective transport embedded within the cold front rather than larger-scale advection along the warm conveyor belt that is dominant in transporting ozone precursors into the free troposphere.

Radiometric levitation of a 20-μ-diam dye-impregnated glycerol sphere has been observed at intensities as low as ∼1 W/cm2 in air at 30 Torr. The levitation has been effected on both strongly absorbing spheres in the direction of the light and weakly absorbing spheres in the opposite sense. Both strongly and weakly absorbing spheres are found to laterally seek an intensity minimum. Consequently particles were stably held in the focused beam of an Ar+ laser (4880 Å) operating in the TEM*01 (doughnut) mode.

Deforestation and drainage has made Indonesian peatlands susceptible to burning. Large fires occur regularly, destroying agricultural crops and forest, emitting large amounts of CO2 and air pollutants, resulting in adverse health effects. In order to reduce fire, the Indonesian government has committed to restore 2.49 Mha of degraded peatland, with an estimated cost of US$3.2-7 billion. Here we combine fire emissions and land cover data to estimate the 2015 fires, the largest in recent years, resulted in economic losses totalling US$28 billion, whilst the six largest fire events between 2004 and 2015 caused a total of US$93.9 billion in economic losses. We estimate that if restoration had already been completed, the area burned in 2015 would have been reduced by 6%, reducing CO2 emissions by 18%, and PM2.5 emissions by 24%, preventing 12,000 premature mortalities. Peatland restoration could have resulted in economic savings of US$8.4 billion for 2004–2015, making it a cost-effective strategy for reducing the impacts of peatland fires to the environment, climate and human health.