• Journal of Korean Society for Atmospheric Environment
• /
• v.10 no.4
• /
• pp.233-244
• /
• 1994

The phenomenon of yellow sand (dust clouds) occurred in Korea during the spring of 1993 and 1994 is studied in detail. In total 6 cases including 15 days of yellow sand were observed in 1993 and the annual number of these events was found to increased. Examinations in this study include meteorological charts satellite imagery, pilot reports (PIREP) of Korea Air Force, and air concentrations of total suspended particulates(TSP). We present on estimation of total atmospheric loadings based on the observation and theory. According to the PIREP, in general the dust clouds travelled in the lower troposphere up to the level 5km. The visibility within the clouds was in the range of 3-8km The area covered by yellow sand in an event exceeded 0.4 M $\textrm{km}^2$ . According to trajectory analyses, dust clouds invaded Korea in April and May 1993 were landed in the sink area after 2~4 days travelling for 2,000~3,000km from a source region. Estimates of total atmospheric loadings of a dust cloud for April 23~24 in 1993 were 1.5 M ton. In addition, 7 dust storms were also reported in synoptic observations in NW China and Mongolia during the spring in 1994. The yellow sand was not reported with meteorological observations in Korea, however pilots reported significant dust clouds over the Yellow Sea on 8 and 13 April and 20 May 1994.

• Atmosphere
• /
• v.22 no.2
• /
• pp.137-147
• /
• 2012

The technique of Brightness Temperature Difference (BTD) between 11 and $12{\mu}m$ separates yellow sand dust from clouds according to the difference in absorptive characteristics between the channels. However, this method causes consistent false alarms in many cases, especially over the desert. In order to reduce these false alarms, we should eliminate the background noise originated from surface. We adopted the Background BTD (BBTD), which stands for surface characteristics on clear sky condition without any dust or cloud. We took an average of brightness temperatures of 11 and $12{\mu}m$ channels during the previous 15 days from a target date and then calculated BTD of averaged ones to obtain decontaminated pixels from dust. After defining the BBTD, we subtracted this index from BTD for the Yellow Sand Index (YSI). In the previous study, this method was already verified using the geostationary satellite, MTSAT. In this study, we applied this to the polar orbiting satellite, MODIS, to detect yellow sand dust over Northeast Asia. Products of yellow sand dust from OMI and MTSAT were used to verify MODIS YSI. The coefficient of determination between MODIS YSI and MTSAT YSI was 0.61, and MODIS YSI and OMI AI was also 0.61. As a result of comparing two products, significantly enhanced signals of dust aerosols were detected by removing the false alarms over the desert. Furthermore, the discontinuity between land and ocean on BTD was removed. This was even effective on the case of fall. This study illustrates that the proposed algorithm can provide the reliable distribution of dust aerosols over the desert even at night.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.1
• /
• pp.41-51
• /
• 2002

This research was carried out using Anderson air sampler which were set up on the roof of the Engineering College of Konkuk University at Hwayang-Dong, Kwangjin-Gu, Seoul from Aug. 1992 to foul. 1999. The results are as follows: The major component of yellow sand is soil particles based upon the observation that particles ranging from $3.3~7.0{\mu}m$ occupy 36~63%. It is certain that the increase of fine particles of respirable dust during yellow sand phenomenon in Seoul area affects the human body. The trace metals from natural sources like Al, Ca, Fe, K, Na, and Si show larger mass median diameter(MMD) values during yellow sand phenomenon than in normal situations while the values of MMD for Mn and Pb rarely changes. Noticeably, the changes in value of MMD of water soluble elements like ${NO_3}^{-}$ and ${SO_4}^{2}$ are 2.3 and 6.6 times higher during the yellow sand phenomenon compared to normal situations, respectively. This fact is regarded as decisive evidence showing that ${NO_3}^{-}$ and ${SO_4}^{2}$ in the air are attached to yellow sand and move together.

• The Korean Journal of Quaternary Research
• /
• v.14 no.1
• /
• pp.49-55
• /
• 2000

The Yellow-Sand phenomena occurred during the period from l0C to 14C in Korea have been investigated using the historical record of the Koryosa. It is written as the "dust rain"or "mud" which means the falling down of dust from the sky. The authors have extracted 50 historical writings of dust rain from the Koryosa. The results show that the observation records concerning Yellow-Sand phenomenon for the period of Korea Dynasty (918~1392) are described with the scientific accuracy for the Yellow-Sand phenomena as the pure dust phenomena, the mixture of Yellow Sand with snow or rain, and the Yellow-Sand associated with fog or hail, etc. It is also found that the occurrence of Yellow-Sand phenomena was the incomprehensible natural phenomena such as Yellow-Sand were interpreted as a warning from the Heaven to the king and people of their fail in moral principles.in moral principles.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.409-414
• /
• 1998

To examine the detectability of the aerosol and/or Yellow dust from China crossing over the Yellow sea, three works carried out as follows , Firstly, a comparison was made of the visible(VIS), water vapor(WV), and Infrared(IR) images of the GMS-5 and NOAA/AVHRR on the cases of yellow sand event over Korea. Secondly, the spectral radiance and reflectance(%) was observed during the yellow sand phenomena on April, 1998 in Seoul using the GER-2600 spectroradiometer, which observed the reflected radiance from 350 to 2500 nm in the atmosphere. We selected the optimum wavelength for detecting of the yellow sand from this observation, considering the effects of atmospheric absorption. Finally, the atmospheric radiance emerging from the LOWTRAN-7 radiative transfer model was simulated with and without yellow sand, where we used the estimated aerosol column optical depth ($\tau$ 673 nm) in the Meteorological Research Institute and the d'Almeida's statistical atmospheric aerosol radiative characteristics. The image analysis showed that it was very difficult to detect the yellow sand region only by the image processing because the albedo characteristics of the sand vary irregularly according to the density, size, components and depth of the yellow sand clouds. We found that the 670-680 nm band was useful to simulate aerosol characteristics considering the absorption band from the radiance observation. We are now processing the simulation of atmospheric radiance distribution in the range of 400-900 nm. The purpose of this study is to present the preliminary results of the aerosol and/or Yellow dust detectability using the Ocean Scanning Multispectral Imager(OSMI), which will be mounted on KOMPSAT-1 as the ocean color monitoring sensor with the range of 400-900 nm wavelength.

• Journal of information and communication convergence engineering
• /
• v.3 no.3
• /
• pp.146-151
• /
• 2005

This paper represents an attempt to bring together and analyses the measurement data measured by the Satellite Signal Monitoring Center in Korea and the Korea Meteorological Administration/Korea Meteorological Research Institute in close cooperation with this study team. This paper presents the signal characteristic of GEO satellite operating in frequency range 1 to 20GHz associated with Asian Sand Dust (the so-called Yellow Sand Dust). The downlink signal power (dBm) for L-, S-, C-, Ku-, and Ka-band frequencies from GEO satellites were measured in a clear weather and in Asian Sand Dust weather by the Satellite Signal Monitoring Center. The measured signal power(dBm) were compared to the total number concentration and size distribution of Sand Dust that were measured by the Korea Meteorological Administration/Korea Meteorological Research Institute and the possible correlation between these sets data were analyzed. The results demonstrate that the downlink signal level (dBm) of GEO satellite is attenuated by Asian Sand Dust. Hitherto, merger information has been reported as to the influence of sand dust on satellite communications operating in regions affected by sand dust.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.370-373
• /
• 2005

We have developed Hybrid algorithm for yellow sand detection. Hybrid algorithm is composed of three methods using infrared bands. The first method used the differential absorption in brightness temperature difference between $11\mu m\;and\;12\mu m$ (BID _1), through which help distinguish the yellow sand from various meteorological clouds. The second method uses the brightness temperature difference between $3.7\mu m\;and\;11\mu m$ (BID_2). The technique would be most sensitive to dust loading during the day when the BID _2 is enhanced by reflection of $3.7\mu m$ solar radiation. The third one is a newly developed algorithm from our research, the so-called surface temperature variation method (STY). We have applied the three methods to MODIS for derivation of the yellow sand dust and in conjunction with the Principle Component Analysis (PCA), a form of eigenvector statistical analysis. PCI shows better results for yellow sand detection in comparison with the results from individual method. The comparison between PCI and MODIS aerosols optical depth (AOD) shows remarkable good correlations during daytime and relatively good correlations over the land.

• Journal of Korean Society for Atmospheric Environment
• /
• v.16 no.5
• /
• pp.487-497
• /
• 2000

Spring time is a favorable season to be easily observed the Yellow Sand phenomenon in East Asia. In particular most of the phenomenon tend to occur in April. However, Yellow Sand phenomenon was observed from almost the whole country of Korea in winter of 1966, 1977 and 1999. The features of the synoptic weather pattern in the source regions, air stream flow between the source region and Korea, the measurement of TSP concentration, aerosol size distribution, and chemical composition of snow samples associated with Yellow Sand phenomenon were investigated. The result showed the characteristic evolutionary feature of the synoptic system associated with Yellow Sand phenomena, that is, a strong low level wind mobilized the dust within 2 or 3 days before Yellow Sand phenomenon being observed in Seoul. The wind was remarkably intensified in the source region on January 24, 1999 under the strong pressure gradient, A trajectory analysis showed that the Yellow Sand particle could be reached to Korea within 2 days from the source region, Gobi desert, through Loess plateau and Loess deposition region. The TSP concentration at the top of Kwanak mountain during the Yellow Sand phenomenon is abruptly increasing than the monthly mean concentration. The size resolved number concentration of aerosols ranging from 0.3 to 25${\mu}{\textrm}{m}$ was analyzed during Yellow Sand episode. It was evident that aerosols were distinguished by particles in the range of 2-3 ${\mu}{\textrm}{m}$ to result in the abrupt increase in January 1999, After Yellow Sand phenomenon, there was heavy snow in Seoul. By the analysis of snow collected during that time, it was observed that both the Ca(sup)2+ concentration and pH were increased abnormally compared to those in the other winter season.

• Journal of Korean Society for Atmospheric Environment
• /
• v.15 no.5
• /
• pp.575-586
• /
• 1999

The size-resolved number concentrations of aerosols ranging from 0.3 to 25 $mu extrm{m}$ were observed in Seoul and Anmyondo in the west coast of Korea during an Yellow Sand phenomenon in April 1998. Number size distributions of aerosols observed in both places are characterized by decrease in small particles of diameter less than 1${\mu}{\textrm}{m}$ and increase in large size between 1.35 and 10${\mu}{\textrm}{m}$ in heavy dust period. For particles in this size range, there was a good correlation between number concentrations observed in both places during the Yellow Sand episode. On the other hand, the number of small particles less than 0.82${\mu}{\textrm}{m}$ decreased, but the correlation between these particles in both places was enhanced during more intense dust period. The number of coarse particle larger than 10 ${\mu}{\textrm}{m}$ showed a distince diurnal variation without a significant change in amplitude, which was more visible in Seoul. It suggests that these coarse particles were more affected by local sources. Form these results, it was range of 1~10${\mu}{\textrm}{m}$ originated possibly from the dust source regions and the source signature depended on the degree of dust intensity.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.149-152
• /
• 2007

The detection of yellow sand dust using satellite has been utilized from various bands from ultraviolet to infrared channels. Among them, Infrared channels have an advantage of detecting aerosols over high reflecting surface as well as during nighttime. Especially, brightness temperature difference between 11 and 12{\mu}m(BTD) was often used to distinguish between water cloud and yellow sand, because Ice and liquid water particles preferentially absorb longer wavelengths while aerosol particles preferentially absorb shorter wavelengths. We have found that the BTD significantly depends on surface temperature, emissivity, and zenith angle and thereby the threshold of BTD. In order to overcome these problems, we have constructed the background brightness temperature threshold of BTD and then subtracted it from BTD. Along with this, we utilized high temporal coverage of geostationary satellite, MTSAT-1R, to verify the reliability of the retrieved signal in conjunction with forecasted wind information. The statistical score test illustrated that this newly developed algorithm showed a promising result for detecting mineral dust by reducing the errors in the current BTD method.