Black Carbon (BC) in the snow of glaciers in west China and its potential effects on albedos. Jing Ming, Cunde Xiao, Helene Cachier, Dahe Qin, Xiang Qin, Zhongqi Li, Jianchen Pu.
Black carbon concentrations in the snow collected from some selected glaciers in west China during 2004–2006 were measured. Higher concentrations appeared at lower sites, possibly due to the topography (e.g. altitude) effect. BC concentrations in snow of Tienshan Mountains outside the Tibetan Plateau (TP) were generally higher than those inside the TP, and strong melting in spring added on more regional/local emissions from the inner TP might both contribute higher concentrations for the central TP than those on the margin of the TP. Comparison between global measured BC concentrations in snow/ice suggested the distance of the sampling site away from strong BC-emitting areas (north mid-latitudes) could be responsible for BC concentrations in snow/ice. A rough estimate for the reduced albedos in some glaciers suggested BC deposited in the surface might accelerate the melt of these glaciers in west China, e.g. HXR48 and MEG3 which were strongly contaminated by BC in their surfaces, the reduced albedos were over 5% due to the BC deposits.
Effects of hygroscopic seeding on raindrop formation as seen from simulations using a 2000-bin spectral cloud parcel model. Segal, Y.; Khain, A.; Pinsky, M.; Rosenfeld, D..
A 2000-bin cloud spectral parcel model is used to investigate the effect of hygroscopic seeding on warm rain formation under different thermodynamic conditions. Simulations show that utilization of commercial hygroscopic flares (“French”, “South African”, New AI and D383) increases raindrop production in those cloud parcels where the natural warm rain process is inefficient. The most effective flare was found to have a maximum fraction of large seeding cloud condensational nuclei (SCCN). An optimum seeding particle radius, which provides the maximum raindrop production under a given mass of the seeding reagent varies from 1.5 to 2.5
Long-term, wintertime aerosol, cloud and precipitation measurements in the Northern Colorado Rocky Mountains. Edward E. Hindman, Randolph D. Borys, Douglas H. Lowenthal, Neal Phillip.
At Storm Peak Laboratory (SPL) in the northern Colorado Rocky Mountains during the winters of 1983/1984 through 2003/ 2004, significant trends occurred of decreasing cloud droplet concentrations and initially increasing cloud and snow pH values then more recent decreasing values. The decrease in cloud droplet concentrations and a corresponding increase in mean droplet diameters are consistent with liquid water content trends in the long-term record. Decreased condensation nucleus concentrations, and most likely cloud-condensation nucleus concentrations as well, caused the decrease in droplet concentrations. An inverse relationship between cloud pH and condensation nucleus concentrations was identified. However, no relationship between condensation nucleus concentrations and precipitation rates was identified. Thus, the inverse relationship between aerosol concentration and precipitation rate reported by Borys et al. [Borys, R.D., Lowenthal, D.H., Cohn, S.A., Brown, W.O.J., 2003. Mountaintop and radar measure ents of anthropogenic aerosol effects on snow growth and snowfall rate. Geophys. Res. Lett. 30, 1538] for SPL was not confirmed. This aerosol effect may be important for only a small subset of winter storms at SPL.