Characteristics of Aeolian Dust Observed by Sky-Radiometer in the Intensive Observation Period 1 (IOP1)

Abstract

A sky-radiometer network was developed in order to investigate the characteristics of aeolian dust on the way of transportation from the source region to the Japan area. From the analysis of the skyradiometer data, optical thickness in the visible to near infrared regions and size spectrum from radius 0.01 to 5 mm can be obtained. Five observation sites are set at Aksu, Qira, Shapotou, Qingdao, and Beijing in China, and four observation sites at Naha, Fukuoka, Nagoya and Tsukuba in Japan. The data of six observation sites (Qira, Shapotou, Naha, Fukuoka, Nagoya and Tsukuba) are automatically transferred to Meteorological Research Institute (MRI) through telephone lines.The following results were obtained from the data analysis of intensive observation period (IOP) in April, 2002. (1) The data with Å ngström exponent between 0.0 and 0.5 corresponds to the dust event day data. (2) The contribution of the particles with radius greater than 0.5 mm, which correspond to coarse dust particles, to the total optical thickness frequently exceeds more than @70% in the source region, and exceeds in Qingdao and sites in Japan on the dust event day. (3) The contribution of particles with radius greater than 0.5 mm to the total volume is more than @80% on the dust event day. (4) The retrieved volume spectrum in the source region, Aksu and Qira, is not dependent on the optical thickness. This means that the floating aerosols mainly consist of dust particles in the source region. (5) The total volume observed in Japan sites is one third of that in the source region. (6) When the size distribution for the coarse mode (r > 0:5 mm) is approximated by log-normal size distribution, effective radius r eff is 2.1 to 2.3 mm in China sites and 1.6 to 1.8 mm in Japan sites. r g is about 0.7 mm at Aksu, Qira, and Shapotou and about 0.5 mm at other sites (ln r g is the center of log-normal size distribution). The width of size distribution ðs g Þ is scattered between 0.67 and 0.87. These difference of size distribution among the observation sites are caused by the modification of air mass including aeolian dust; coarser dust particles are partially removed during the transportation, and the air mass including aeolian dust as a main component are partially contaminated by the aerosol into the atmosphere from anthropogenic activities. The observation network of ADEC caught this change clearly.

Retrieval of Asian Dust Amount over Land using ADEOS-II/GLI near UV Data

“…The result is a little bit larger than the retrieved mode radius for the coarse mode (1 to 6 µm) with the skyradiometer observation (Uchiyama et al 2005), but it is reasonable for Kosa particles in the same order of magnitude. The GLI retrieved optical thickness 0.34 at 500nm is larger than the value of 0.30 with a LIDAR measurement at 532 nm (Yasui et al 2005), and, on the other hand, smaller than the value of 0.59 at 500nm with a skyradiometer measurement.…”

“…where N is a number of particles, r is a particle radius, c is an arbitrary constant which is normalized as a total particle number, r0 is a mode radius, and is a standard deviation, which is expressed as lns The value s is assumed as 2.0 (Uchiyama et al 2005).…”

Aerosol optical properties and radiative effect determined from sky-radiometer over Loess Plateau of Northwest China

“…Many efforts have been devoted to measure aerosol optical and physical properties (Holben et al, 2001;Takemura et al, 2002;Dubovik et al, 2002;Smirnov et al, 2002;Nakajima et al, 2003;Aoki and Fujiyoshi, 2003;Kim et al, 2004;Eck et al, 2005). Uchiyama et al (2005) studied the characteristics of aeolian dust observed by sky-radiometer at several sites including some in source region. Li et al (2007) Retrieving from sky-radiometer measured at Anmyeon, Korea, Sohn et al (2007) pointed out that Asian dusts can become more absorbing aerosols when mixed with pollutants.…”

Assessment of In-situ Langley Calibration of CE-318 Sunphotometer at Mt. Waliguan Observatory, China

“…Several international and regional networks of ground-based photometers such as AErosol RObotic NETwork-AERONET (Holben et al 1998), SKYradiometer NETwork-SKYNET (Kim et al 2004;Uchiyama et al 2005), the Global Atmosphere Watch Precision Filter Radiometer-GAW PFR network (Wehrli 2002), and China Aerosol Research Network-CARSNET (Che et al 2009) have been set up over the past 20 years, taking advantage of the development of new instruments and techniques for the systematic observation of optical, microphysical and radiative aerosol properties from the ground.…”