We present evidence for the first observation of electromagnetically bound \(\pi^\pm K^\mp\)-pairs (\(\pi K\)-atoms) with the DIRAC experiment at the CERN-PS. The \(\pi K\)-atoms are produced by the ...24 GeV/c proton beam in a thin Pt-target and the \(\pi^\pm\) and \(K^\mp\)-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 \(\pm\) 54 \(\pi K\)-atoms. The mean life of \(\pi K\)-atoms is related to the s-wave \(\pi K\)-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level.
The VAMOS Ocean-Cloud-Atmosphere-Land Regional Experiment (VOCALS-REx) was conducted from 15 October to 15 November 2008 in the South East Pacific (SEP) region to investigate interactions between ...land, sea and atmosphere in this unique tropical eastern ocean environment and to improve the skill of global and regional models in representing the region. This study synthesises selected aircraft, ship and surface site observations from VOCALS-REx to statistically summarise and characterise the atmospheric composition and variability of the Marine Boundary Layer (MBL) and Free Troposphere (FT) along the 20° S parallel between 70° W and 85° W. Significant zonal gradients in mean MBL sub-micron aerosol particle size and composition, carbon monoxide, sulphur dioxide and ozone were seen over the campaign, with a generally more variable and polluted coastal environment and a less variable, more pristine remote maritime regime. Gradients in aerosol and trace gas concentrations were observed to be associated with strong gradients in cloud droplet number. The FT was often more polluted in terms of trace gases than the MBL in the mean; however increased variability in the FT composition suggests an episodic nature to elevated concentrations. This is consistent with a complex vertical interleaving of airmasses with diverse sources and hence pollutant concentrations as seen by generalised back trajectory analysis, which suggests contributions from both local and long-range sources. Furthermore, back trajectory analysis demonstrates that the observed zonal gradients both in the boundary layer and the free troposphere are characteristic of marked changes in airmass history with distance offshore – coastal boundary layer airmasses having been in recent contact with the local land surface and remote maritime airmasses having resided over ocean for in excess of ten days. Boundary layer composition to the east of 75° W was observed to be dominated by coastal emissions from sources to the west of the Andes, with evidence for diurnal pumping of the Andean boundary layer above the height of the marine capping inversion. Analysis of intra-campaign variability in atmospheric composition was not found to be significantly correlated with observed low-frequency variability in the large scale flow pattern; campaign-average interquartile ranges of CO, SO2 and O3 concentrations at all longitudes were observed to dominate over much smaller differences in median concentrations calculated between periods of different flow regimes. The campaign climatology presented here aims to provide a valuable dataset to inform model simulation and future process studies, particularly in the context of aerosol-cloud interaction and further evaluation of dynamical processes in the SEP region for conditions analogous to those during VOCALS-REx. To this end, our results are discussed in terms of coastal, transitional and remote spatial regimes in the MBL and FT and a gridded dataset are provided as a resource.
Under current support from ONR we have initiated a study of the sea-salt aerosol field generated around Hawaii. We have been focused upon measurements of sea-salt production from open-ocean breaking ...waves during wave and whitecap intensification over a 100km fetch present in the Alenuihaha channel between the islands of Maui and Hawaii. We have deployed aerosol instrumentation package aboard a tugboat that crosses the channel biweekly. The package has been deployed in March of 2005 and operated continuously during spring-summer 2005 to generate a database on the channel aerosol generation. We have demonstrated that, due to island mountain topography, the induced steady-state accelerated trade-wind flow in the Alenuihaha channel provides an ideal "natural wind-tunnel" for the study of sea- salt aerosol production, turbulent mixing, particle fluxes and related optical effects under real oceanic conditions. The winds are accelerated between mountains on Maui and Hawaii and are nearly double wind speeds over those of the open-ocean trade wind region, as seen in the MM5 model output. This enhancement in the sea-salt production is evident in our near- surface lidar data and light scattering data. However, the aerosol concentrations reveal more detailed structure when examined on an expanded scale. We find that small organized structures such as cloud streets also influence the aerosol and optical structure in the boundary layer aerosol. Fingerlike projections of high backscatter originate near the surface below clouds and lower backscatter tongues project down between them. Some of this difference is related to rising air with higher relative humidity (RH) below cloud and tongues with lower RH between them (perhaps due to entrained dry air from the free troposphere). Near-surface dry coarse aerosol scattering is also enhanced in the rising fingers indicating both sea-salt aerosol and RH are higher in these rising regions. Both enhanced sea-salt production under high wind and the relation to activated cloud droplets have been explored in this environment.
The history of Soviet oceanology Brekhovskikh, Leonid M; Neiman, Victor G; Watson, Traci
Oceanus (Woods Hole),
07/1991, Letnik:
34, Številka:
2
Magazine Article
Research institutes, as well as ships, have been added to the Soviet oceanology community over the last four decades. By the end of the 1960s, a network of oceanology institutes stretched across the ...Soviet Union, including the P.P. Shirshov Institute of Oceanology and the State Oceanographic Institute in Moscow; the All-Union Research Institute of Marine Fisheries and Oceanography in Leningrad; the Arctic and Antarctic Research Institute in Sevastopol; and the Marine hydrophysical Institute and the Institute of Biology of Southern Seas in Vladivostok. Moscow, Leningrad, and Vladivostok remain the centers of research, with regional outposts in coastal cities.
The Hawaii Group for Environmental Aerosol Research http://www.soest.hawaii.edu/HIGEAR deployed a wide range of aerosol instrumentation aboard the C-130 and the NASA DC-8 as part of MILAGRO/INTEX. ...These were designed to provide rapid information on aerosol composition, state of mixing (internal or external), spectral optical properties (scattering and absorption), the humidity dependence of light scattering-f(RH), and the role of condensed species in changing the absorption properties of black carbon (BC) and inferred properties of organic carbon (OC). These measurements included size distributions from about 7 nm up to about 10,000 nm and their volatility at 150, 300 and 400 C; size selected response to heating (volatility) to resolve the state of mixing of the aerosol; continuous measurements of the light scattering and absorption at 3 wavelengths; measurements of the f(RH). We also flew the first airborne deployment of the new Fast Mobility Particle Sizer (FMPS, TSI Inc.) that provided information on rapid (1Hz) size variations in the Aitken mode. This revealed small scale structure of the aerosol and allowed us to examine size distributions varying over space and time associated with mixing processes previously unresolved etc. Rapid measurements during profiles also revealed variations in size over shallow layers. Other dynamic processes included rapid size distribution measurements within orographically induced aerosol layers and size distribution evolution of the nanoparticles formed by nucleation (C-130 flights 5, 6 and 9). Evidence for fluctuations induced by underlying changes in topography was also detected. These measurements also frequently revealed the aerosol variability in the presence of boundary layer rolls aligned along the wind in the Marine Boundary Layer (Gulf region) both with and without visible cloud streets (DC-8 flight 4 and C-130 flight 7). This organized convection over 1-2 km scales influences the mixing processes (entrainment, RH) and related variability of aerosol concentration and optical properties.
