Gakuji Kurata

Evolution of mixing state of black carbon particles : Aircraft measurements over the western Pacific in March 2004

0.63within12hours(h),namely2.3%h 1 ,afterbeingemitted from the Nagoya urban area in Japan. BC particles with a core diameter of 250 nm increased at the slower rate of 1.0% h 1 . The increase in coated BC particles was associated with increases in non-sea salt sulfate and water-soluble organic carbon by a factor of approximately two, indicating that these compounds contributed to the coating on the BC particles. These results give direct evidence that BC particles become internally mixed on a time scale of 12 h in urban plumes. Citation: Moteki, N., Y. Kondo, Y. Miyazaki, N. Takegawa, Y. Komazaki, G. Kurata, T. Shirai, D. R. Blake, T. Miyakawa, and M. Koike (2007), Evolution of mixing state of black carbon particles: Aircraft measurements over the western Pacific in March 2004,Geophys. Res. Lett., 34, L11803, doi:10.1029/2006GL028943.

Influences of biomass burning during the Transport and Chemical Evolution Over the Pacific (TRACE-P) experiment identified by the regional chemical transport model

(� HCN/� CO � 0.0015) and potassium (� K + /� CO � 0.0038) but very low NOy (� NOy/ � CO � 0.005) mixingratios,whichmaybeassociated withthespecialburning condition in this region. The biomass burning air masses have high ozone production efficiency. The observedO3/� NOz values were � 17 in biomass events and 1.7 in other events. The BB influence on the trace gas distributions can be divided into two categories: the influence through direct reactions and the influence caused by BB aerosols changing J values. These two influences are discussed for the BB-affected TRACE-P flights and for east Asia. The BBinfluencesonchemicalspeciesarenotonlydeterminedbytheBBplumeintensitybutalso bytheambientenvironmentcausedbyotheremissions.InSoutheastAsia,wherethebiogenic emissions are very strong, the OH background concentration is low, and the BB gas-phase compounds mainly contribute to OH production. Arranged in the sensitivity to the J value change caused by BB aerosols, we have OH > HO2 > HCHO > O3 when evaluated on a regional average.AveragedoverMarch,thebiomassburningnetinfluenceisashighas50% forOH,40%forHO2,60%forHCHO,and10ppbvforO3forthelayersbelow1km. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0345 Atmospheric Composition and Structure: Pollution—urbanandregional(0305);3337MeteorologyandAtmospheric Dynamics:Numericalmodelingand data assimilation; 3359 Meteorology and Atmospheric Dynamics: Radiative processes; KEYWORDS: biomass burning, chemical transport model, TRACE-P, photochemical process, aerosols, radiative influence Citation: Tang, Y., et al., Influences of biomass burning during the Transport and Chemical Evolution Over the Pacific (TRACE-P) experiment identified by the regional chemical transport model, J. Geophys. Res., 108(D21), 8824, doi:10.1029/2002JD003110, 2003.

Multiscale simulations of tropospheric chemistry in the eastern Pacific and on the U.S. West Coast during spring 2002

[ 1] Regional modeling analysis for the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) experiment over the eastern Pacific and U. S. West Coast is performed using a multiscale modeling system, including the regional tracer model Chemical Weather Forecasting System (CFORS), the Sulfur Transport and Emissions Model 2003 (STEM-2K3) regional chemical transport model, and an off-line coupling with the Model of Ozone and Related Chemical Tracers ( MOZART) global chemical transport model. CO regional tracers calculated online in the CFORS model are used to identify aircraft measurement periods with Asian influences. Asian-influenced air masses measured by the National Oceanic and Atmospheric Administration (NOAA) WP-3 aircraft in this experiment are found to have lower DeltaAcetone/DeltaCO, DeltaMethanol/DeltaCO, and DeltaPropane/DeltaEthyne ratios than air masses influenced by U. S. emissions, reflecting differences in regional emission signals. The Asian air masses in the eastern Pacific are found to usually be well aged (> 5 days), to be highly diffused, and to have low NOy levels. Chemical budget analysis is performed for two flights, and the O-3 net chemical budgets are found to be negative ( net destructive) in the places dominated by Asian influences or clear sites and positive in polluted American air masses. During the trans-Pacific transport, part of gaseous HNO3 was converted to nitrate particle, and this conversion was attributed to NOy decline. Without the aerosol consideration, the model tends to overestimate HNO3 background concentration along the coast region. At the measurement site of Trinidad Head, northern California, high-concentration pollutants are usually associated with calm wind scenarios, implying that the accumulation of local pollutants leads to the high concentration. Seasonal variations are also discussed from April to May for this site. A high-resolution nesting simulation with 12-km horizontal resolution is used to study the WP-3 flight over Los Angeles and surrounding areas. This nested simulation significantly improved the predictions for emitted and secondary generated species. The difference of photochemical behavior between the coarse (60-km) and nesting simulations is discussed and compared with the observation.

Numerical Simulation of Air Pollution Transport Under Sea/Land Breeze Situation in Jakarta, Indonesia in Dry Season

Air pollution in Jakarta in dry season (6–19 August 2004) was numerically investigated by using CTM. Obtained results showed: Pollutants rich air mass, which was transported from Jakarta to Java Sea by land breeze, was found as source of ozone rich air mass brought into Jakarta by sea breeze. Shallow sea breeze with 400 m in depth and thermal internal boundary layers caped by strong stable layer resulted in a characteristic ozone concentration profile with low at ground and high at 300 m. Shallow sea breeze layer was due to synoptic easterly and southeasterly in this season.

Effect of Biomass Burning on Tropospheric Chemistry in Southeast ASIA — A Numerical Simulation for September and October, 1994

Numerical simulation of the transport/chemistry/deposition of trace chemical species was performed to see the influence of biomass burning in tropical Asia on concentrations of ozone and CO and tropospheric chemistry for September and October in 1994. Some of the obtained results are as follows: (1) In tropical Asia, two different meteorological situations in synoptic scale coexisted; dry and stably stratified atmosphere over Java and southern Kalimantan, Indonesia, and wet and unstable atmosphere with active cumulus convection over Sumatra, northern Kalimantan, and the Malay Peninsula. Effect of these different atmospheric conditions on ozone and CO were evaluated. (2) Increase in ozone and CO mixing ratios by biomass burning source was quantified: for example, ozone increased roughly by 3–4 ppb at Kuala Lumpur (which was much smaller than the increase of 20 ppb by other anthropogenic emission sources), and by 8–9 ppb at Watukosek, Java. Surface ozone at Singapore (Fig. 5) showed similar tendency to that at KL; ozone increased 3–4 ppb by the biomass burning and 10–15 ppb by the other sources. (3) Predicted ozone column density (Fig. 7) suggested importance of emission sources in southern coastal China and Southeast Asia because of coexistence of strong source and cumulus convection. (4) Inclusion of initial plume rise for biomass fire emission can be important because of different chemical reaction rate and longer lifetime in free troposphere.