Aircraft Observations of Dust and Pollutants over NE China: Insight into the Meteorological Mechanisms of Long-Range Transport

Substantial concentrations of trace gases and aerosols are lofted and carried from Asia over the Pacific producing an inter-hemispheric impact on atmospheric chemistry and climate. The meteorological mechanism leading to this large-scale transport of dust and pollutants remains a major uncertainty in quantifying the global effects of emissions from the developing world. Models and downwind measurements have identified isentropic advection associated with wave cyclones (warm conveyor belt circulation) as an important mechanism. We present data from a case study conducted over Shenyang in NE China as part of EAST-AIRE in April 2005 in which upstream convection, rather than WCB lofting appears to dominate. Observations from instrumented aircraft flights, back trajectories, and satellite images of clouds (GOES) and aerosols (MODIS) are analyzed. In this heavily industrialized and populated region, the warm-sector PBL air ahead of a cold front was highly polluted. In the free troposphere, between ~1000 and 4000 m altitude, concentrations of trace gases and aerosols were lower, but well above background; we measured ~70 ppb O3, ~300 ppb CO, ~2 ppb SO2, and ~ 8x10-5 m-1 aerosol scattering. These observations show that dry (non-precipitating) convection can be an important mechanism for converting local air pollution problems into regional or global atmospheric chemistry problems. Climatological data indicate that spring (MAM) precipitation over NE China is low, about 90 mm compared to 290 mm over the NE US. Cloud cover, however, is similar with cumulus clouds reported about 7% of the time over NE China and about 9% of the time over the NE US suggesting that lofting in dry convective events may be common over NE Asia. Evaluation of models’ convective schemes and further observations near the source regions are called for.NS

Biofuel availability and domestic use patterns in Kenya

The annual domestic consumption levels and patterns of various common biofuels in Kenya were surveyed. The main fuelwood sources were farmland trees, indigenous forests, woodlands and timber off-cuts from plantations. In 1997, about 15.4 million tonnes of firewood (air-dried) were consumed and an equivalent of 17.1 million tonnes round wood wet weight (w/w) was converted to charcoal. In the same year, 1.4 million tonnes of a variety of crop residues were also consumed as domestic fuel. Biofuel availability was the major factor influencing the reported annual spatial species use and consumption patterns. Competing demand for the commonly-used tree species (mainly eucalyptus trees) for commercial and other purposes accounts, to a large extent, for the reported dwindling amounts. Communities in various regions have responded by gradually shifting to other available types including those in gazetted forests. Such a response strategy has implications on the long-term spatial and temporal biofuel use patterns

Biofuel consumption rates and patterns in Kenya

A questionnaire survey was conducted in rural and urban Kenya to establish biofuel consumption rates and patterns. The survey targeted households, commercial catering enterprises and public institutions such as schools and colleges. Firewood was the main biofuel used, mostly by rural households, who consumed the commodity at average consumption rates in the range 0.8–2.7 kg cap−1 day−1. Charcoal was mostly consumed by the urban households at weighted average rates in the range 0.18–0.69 kg cap−1 day−1. The consumption rates and patterns for these fuels by restaurants and academic institutions, and those for crop residues are also reported. The rates largely depended on the fuel availability but differed significantly among the three consumer groups and between rural and urban households. Other factors which may have influenced consumption rates are discussed. Although good fuelwood sufficiency was reported in the country in 1997, there were increasing difficulties in accessing these resources by most households, a situation having both short- and long-term implications for biofuel consumption rates and patterns