New Particle Formation Events During 2013 in Hada Al Sham, Saudi-Arabia

Abstract:

New particle formation (NPF) is the dominant source of aerosol particles in the atmosphere and plays an important role in the global climate (Kulmala et al., 2013). NPF events has been observed in various places around the world (Kulmala et al., 2007). Arabian Peninsula has one of the highest aerosol burdens due to dust storms, local petroleum industry, traffic and advection from southern Asia. Here we present results of new particle formation event analysis from the first full year of measurements in the new measurement station in Hada Al Sham, Saudi-Arabia.

The background station in Hada Al Sham (21.802° North, 39.729° East, 254 m a.s.l.) was founded at the end of 2012 on an agricultural test field 60 km to southeast from the city of Jeddah. The terrain around the station is arid desert with very scarce yearly precipitation. There are no local pollution sources. Main instrumentation include: PM_2.5 and PM₁₀, number size distribution (7 nm - 10 μm) and total concentration, absorption and scattering coefficients, and the basic weather parameters.

We analysed the twin DMPS data from year 2013 classifying new particle formation events by visual day-to-day method. The days were classified following the principal presented in Dal Maso et al., (2005). The data coverage was 264 days (72.3 %) of the year. 210 Days (79.5 %) were classified as NPF event (Class I and II) days, 37 days (14.0 %) as undefined and 17 days (6.4 %) as non-event days.

The analysis of the NPF event days was considered again as the freshly formed particles was observed shrinking after the original growth in most of the NPF event days. Typical event day DMPS data with a shrinking mode of particles is presented in Fig.1. Some of the days involved simultaneous shrinking and growth of the particles. Table 1 summarizes the frequency of each type of event day.

Events	G	S	G + S	unclear
210	25	102	33	50	Days
100	11.9	48.6	15.7	23.8	(%)

Table 1. Reclassification of the event days (classes I and II). G is clear growth, S is clear shrinkage, G + S is both growth and shrinkage and unclear is not clear in either way.

References

M. Dal Maso, et al. (2005). Bor. Env. Res., 10, 323-336.

M. Kulmala, et al. (2006). Atmos. Chem. Phys., 6, 787-793.

M. Kulmala, et al. (2013). Science, 336, 943-946.