A novel optical aerosol detector utilizing an optic fiber with conductive polymer coating

Qin, Hongyi,Kulkarni, Atul,Zhang, Hang,Jiang, Dong,Kim, Taesung Elsevier 2012 Journal of aerosol science Vol.45 No.-

<P><B>Abstract</B></P><P>The detection of atmospheric aerosol particles is becoming an important issue in many fields such as environmental science, occupational medicine, semiconductor industry and material science. In the present paper, we utilized the conductive polymer, polypyrrole (PPy), as a sensitive membrane for detecting aerosol particles optically. A polymer optical fiber reflectance probe is constructed by depositing the PPy nanofilm at the end face of the fiber. The sensor principle relies on the change in the refractive index of the PPy nanofilm upon its interaction with aerosol nanoparticles and on the electrostatic induction between aerosol particles and the PPy nanofilm, which leads to a change in the reflected intensity. For preliminary evaluation of optical aerosol detector, three types of aerosol particles, NaCl, black carbon (BC) and polystyrene latex (PSL), are selected. The fabricated fiber optic reflectance probe using the PPy nanofilm shows distinct variations in the reflected light intensity depending on the type of aerosol particle and its properties. The proposed sensing approach may promote the use of conductive polymers in optical techniques for the detection of atmospheric aerosols.</P> <P><B>Highlights</B></P><P>► A novel optical fiber sensor based on the polypyrrole nanofilm for aerosol detection. ► The electrostatic induction between aerosol particles and polypyrrole nanofilm is utilized as the detection mechanism. ► This novel optical detection approach shows a good sensitivity for the aerosol detection.</P>

GOCI-II 자외선 채널을 활용한 흡수성 에어로졸 관측

이서영 ( Seoyoung Lee ),김준 ( Jhoon Kim ),안재현 ( Jae-hyun Ahn ),임현광 ( Hyunkwang Lim ),조예슬 ( Yeseul Cho ) 대한원격탐사학회 2021 大韓遠隔探査學會誌 Vol.37 No.6

2020년 2월 19일 천리안 2B호의 해양 탑재체 GOCI-II가 발사되었다. GOCI-II 기기는 이전의 GOCI 대비 여러 향상된 기능을 탑재함으로써, 에어로졸 산출 연구의 범위를 확장해주었다. 특히, 새롭게 추가된 380 nm 자외선 채널은 흡수성 에어로졸 관측의 민감도를 유의미하게 향상시키는 역할을 하였다. 본 연구에서는, GOCI-II의 380 및 412 nm 채널을 활용하여 2021년 1월부터 6월까지의 에어로졸 지수를 계산하고 이를 통해 흡수성 에어로졸을 탐지하였다. TROPOMI 에어로졸 지수와 비교한 결과 GOCI-II 에어로졸 지수는 양의 편차를 보였으나, 황사 화소에서의 에어로졸 지수는 구름 및 청천 화소와 뚜렷하게 구분할 수 있을 만큼 더 크게 나타났다. 또한 GOCI-II 에어로졸 지수가 크게 나타날 때, 지상 관측 장비에서도 흡수성 에어로졸이 우세하게 탐지되었음을 발견하였다. GOCI-II 에어로졸 지수 상위 25% 범위에 드는 자료들을 조사하자, 연구 기간 동안 지상에서 Dust 및 Moderately-absorbing fine 유형으로 확인된 자료들의 71.3%, 80.0%가 각각 여기에 속함을 확인할 수 있었다. On 19 February 2020, the 2nd Geostationary Ocean Color Imager (GOCI-II), a maritime sensor of GEO-KOMPSAT-2B, was launched. The GOCI-II instrument expands the scope of aerosol retrieval research with its improved performance compared to the former instrument (GOCI). In particular, the newly included UV band at 380 nm plays a significant role in improving the sensitivity of GOCI-II observations to the absorbing aerosols. In this study, we calculated the aerosol index and detected absorbing aerosols from January to June 2021 using GOCI-II 380 and 412 nm channels. Compared to the TROPOMI aerosol index, the GOCI-II aerosol index showed a positive bias, but the dust pixels still could be clearly distinguished from the cloud and clear pixels. The high GOCI-II aerosol index coincided with ground-based observations indicating dust aerosols were detected. We found that 70.5% of dust and 80% of moderately-absorbing fine aerosols detected from the ground had GOCI-II aerosol indices larger than the 75th percentile through the whole study period.

지상관측장비를 이용하여 관측한 봄철 황사의 연직분포와 광학적 특성 분석

이병일(Byung-Il Lee),윤순창(Soon-Chang Yoon),김윤재(Yoonjae Kim) 한국기상학회 2008 대기 Vol.18 No.4

The vertical profiles and optical properties of Asian dust are investigated using ground-based measurements from 1998 to 2002. Vertical profiles of aerosol extinction coefficient are evaluated using MPL (Micro Pulse Lidar) data. Optical parameters such as aerosol optical thickness (τ), Angstrom exponent (α), single scattering albedo (ω), refractive index, and volume size distribution are analyzed with sun/sky radiometer data for the same period. We can separate aerosol vertical profiles into three categories. First category named as 'Asian dust case', which aerosol extinction coefficient is larger than O. I 5 ㎞<SUP>-1</SUP> and dust layer exists from surface up to 3-4 ㎞. Second category named as 'Elevated aerosol case', which aerosol layer exists between 2 and 6 ㎞ with 1-2.5 ㎞ thickness, and extinction coefficient is smaller than 0.15 ㎞<SUP>-1</SUP>. Third category named as 'Clear sky case', which aerosol extinction coefficient appears smaller than 0.05 ㎞<SUP>-1</SUP> and shows that diurnal variation of background aerosol in urban area. While optical parameters for first category indicate that τ and a are 0.63±0.14, 0.48±0.19, respectively. Also, aerosol volume concentration is increased for range of 1 and 4 ㎛, in coarse mode. Optical parameters for second category can be separated into two different types. Optical properties of first type are very close to Asian dust cases. Also, dust reports of source region and backward trajectory analyses assure that these type is much related with Asian dust event. However, optical properties of the other type are similar to those of urban aerosol. For clear sky case, τ is relatively smaller and a is larger compare with other cases. Each case shows distinct characteristics in aerosol optical parameters.

Impact of COVID-19 on spatio-temporal variation of aerosols and air pollutants concentration over India derived from MODIS, OMI and AIRS

Yashwant B. Katpatal,Vikas K. Patel,Digambar S. Londhe 대한공간정보학회 2023 Spatial Information Research Vol.31 No.6

The atmospheric aerosols and air pollutants affect the earth's atmosphere, human health and climate system. Human-induced aerosols and air pollutants are the major causes of the deterioration of air quality. The COVID-19 lockdown restricted the movement of people and vehicles, stopped industrial and agricultural activities and may have impacts on the aerosols in the atmosphere. Spatio-temporal map of MODIS Terra AOD_550 nm, OMI Aura UVAI, Ozone, NO2, SO2 and AIRS CO during the lockdown illustrates the significant reduction in their concentration. During the lockdown, the North India shows a record reduction of over 20% in Aerosol Optical Depth and Aerosol Index values. A substantial decrease in AOD and AI was also observed in Eastern and Western parts of India. The average AOD value were reduced from 1.36 (2016–2019) to 1.09 (2020) over India during the lockdown. The satellite-retrieved aerosol variables over India recorded lowest AOD values on 29th March, 2020 (0.2566) and 21st April 2020 (0.2591). Similarly, air pollutants CO, NO2 and SO2 also significantly reduced in India. Despite all variables showing a reduction in concentration, Ozone recorded an increase in value during lockdown primarily over North and North-eastern parts of India. Western India recorded a substantial reduction in SO2 (47%) followed by Central India (31%). As pan India is considered, CO was reduced by 1%, NO2 reduced by 15.29% and SO2 was reduced by 26.82% during the lockdown period. This abrupt reduction in aerosol and air pollutants concentration over India was mainly due to the lockdown of COVID-19.

Forecast of UV-index over Korea with Improved Total Ozone Prediction and Effects of Aerosols, Clouds and Surface Albedo

이윤곤,김준,조히구,최병철,김지영,정성래,박일수 한국기상학회 2008 Asia-Pacific Journal of Atmospheric Sciences Vol.44 No.4

New ultraviolet (UV) index forecast model was developed by using radiative transfer model and improved multiple linear regression for total ozone prediction using new predictors based on extensive investigation on their correlations with total ozone, and new modification factor for clouds, aerosols and surface reflectance. For clear sky case, root mean square error (RMSE) of newly-forecasted UV index with respect to observations is reduced by 16.0% with using improved forecast of total ozone,by 25.2% with cloud modification factor (CMF) applied, and by 32.7% with CMF and aerosol modification factor (AMF) compared to the existing forecast at Korea Meteorological Administration (KMA), which utilized the state-of-the-art UV radiative transfer model together with multiple regression model. The percentage improvement is estimated to be 16.0% through the application of new total ozone forecast, 9.2% with the new CMF, and 7.5% with the new AMF. The accuracy of UV index forecast for cloudy skies is subjected to the errors of next day’s cloud forecast for the modification, but the forecast of UV index for clear sky conditions shows significant improvement.

위성기반의 한반도 식물계절학적 패턴과 대기 에어로졸의 시계열 특성 분석

박선엽(Sunyurp Park) 대한지리학회 2013 대한지리학회지 Vol.48 No.4

본 연구의 목적은 기후요소와 대기 에어로졸이 한반도 식물계절학적 특성에 미치는 영향을 위성자료 분석을 통해 규명하는 것이다. 매일 관측되는 위성관측 자료의 분석을 통해 지표관측이 갖는 식물계절학적 연구상의 시계열적 한계를 극복하고자 하였다. 연구결과에 따르면, 분석된 4개의 주요 산림생태계 중 상록수림, 낙엽수림, 초지는 서로 유사한 식물계절학적 특성을 보인 반면, 혼합림의 생장 패턴의 연도별변화는 상이하게 나타났다. 식생지수(VI)의 연중 진폭이 큰 삼림은 VI 연중 최대치에 보다 빨리 도달하는 것으로 조사되었지만, 동일 삼림생태계 내에서는 시계열적인 관련성이 나타나지 않았다. 식생지수의 위상(phase)은 VI 최대치가 관측되는 연중 시점을 의미하는데, 기온의 변화와 강한 상관성을 보였다. 에어로졸 광학두께(AOT)의 시계열변화는 연도별 변화뿐만 아니라 계절적 특징을 강하게 나타내었다. 일반적으로, 에어로졸 농도는 늦봄부터 초여름에 걸쳐 가장 높게 나타났다. 하지만 AOT의 연도별변화 패턴은 진폭과 위상 변화 측면에서 식생지수와 통계적으로 강한 상관관계를 보이지 않았다. 단지, AOT의 연중 진폭(amplitude)이 식생지수의 진폭과 미약한 상관관계를 보인 결과로 볼 때, 전반적인 에어로졸의 농도 변화가 식생활동에 영향을 미칠 개연성이 있다고 판단된다. The objective of this study is to determine the spatiotemporal influences of climatic factors and atmospheric aerosol on phenological cycles of the Korea Peninsular on a regional scale. High temporalresolution satellite data can overcome limitations of ground-based phenological studies with reasonable spatial resolution. Study results showed that phenological characteristics were similar among evergreen forest, deciduous forest, and grassland, while the inter-annual vegetation index amplitude of mixed forest was differentiated from the other forest types. Forest types with high VI amplitude reached their maximum VI values earlier , but this relationship was not observed within the same forest type. The phase of VI, or the peak time of greenness, was significantly influenced by air temperature. Aerosol optical thickness (AOT) time-series showed strong seasonal and inter-annual variations. Generally, aerosol concentrations were peaked during late spring and early summer. However, inter-annual AOT variations did not have significant relationships with those of VIs. Weak relationships between AOT amplitude and EVI amplitude only indicates that there would be potential impacts of aerosols on vegetation growth in the long run.

The Detection of Yellow Sand with Satellite Infrared bands

Ha, Jong-Sung,Kim, Jae-Hwan,Lee, Hyun-Jin The Korean Society of Remote Sensing 2006 大韓遠隔探査學會誌 Vol.22 No.5

An algorithm for detection of yellow sand aerosols has been developed with infrared bands. This algorithm is a hybrid algorithm that has used two methods combined. The first method used the differential absorption in brightness temperature difference between $11{\mu}m\;and\;12{\mu}m\;(BTD1)$. The radiation at $11{\mu}m$ is absorbed more than at $12{\mu}m$ when yellow sand is loaded in the atmosphere, whereas it will be the other way around when cloud is present. The second method uses the brightness temperature difference between $3.7{\mu}m\;and\;11{\mu}m(BTD2)$. This technique is sensitive to dust loading, which the BTD2 is enhanced by reflection of $3.7{\mu}m$ solar radiation. First the Principle Component Analysis (PCA), a form of eigenvector statistical analysis from the two methods, is performed and the aerosol pixel with the lowest 10% of the eigenvalue is eliminated. Then the aerosol index (AI) from the combination of BTD 1 and 2 is derived. We applied this method to Multi-functional Transport Satellite-l Replacement (MTSAT-1R) data and obtained that the derived AI showed remarkably good agreements with Ozone Mapping Instrument (OMI) AI and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth.

Environmental Analysis in Asian Dust Source Region Using Satellite Remotely Sensed Data

Kyung, Hye-Mee,Kim, Young-Seup,Kim, Sang-Woo The Korean Society of Remote Sensing 2003 大韓遠隔探査學會誌 Vol.19 No.3

With the negative influences and damage from Asian dust increasing, it's getting important to investigate the climate and soil condition of the source region of Asian dust. There is a high possibility that the desertification and the drastic decrease of plants in China and Mongolia make worse the situation (bad effects of Asian Dust). To detect the movement of Asian dust caused by air circulation, we need to watch the state of the source region to get useful information for the prevention of the dust pollution, and to predict what part of China will become the source region. Therefore, using TOMS aerosol index data, NCEP reanalysis data that is Remote Sensing data from 1981 to 2000 (except 1993~1996, 4 years), for 16 years, examined the relation between the dust occurrence and weather elements. Dust occurrence appeared much in spring season from March to May in study areas. It had a dry climate during that season as follows : relative humidity about 20~40%, temperature about -5~5$^{\circ}C$, precipitation about 33-180 mm, wind speed about 4-10 ms-1. Dust occurrence and weather element annual change in study areas decreased gradually till 1990, but in Gobi desert the incidence of dust occurrence increased since 1997. As a result, found out that the more the precipitation, the less dust occurrence, because the precipitation and surface wind speed had a direct influence on the soil of the source region of dust.

Environmental Analysis in Asian Dust Source Region Using Satellite Remotely Sensed Data

Hye Mee Kyung,Young Seup Kim,Sang Woo Kim 大韓遠隔探査學會 2003 大韓遠隔探査學會誌 Vol.19 No.3

With the negative influences and damage from Asian dust increasing, it`s getting important to investigate the climate and soil condition of the source region of Asian dust. There is a high possibility that the desertification and the drastic decrease of plants in China and Mongolia make worse the situation (bad effects of Asian Dust). To detect the movement of Asian dust caused by air circulation, we need to watch the state of the source region to get useful information for the prevention of the dust pollution, and to predict what part of China will become the source region. Therefore, using TOMS aerosol index data, NCEP reanalysis data that is Remote Sensing data from 1981 to 2000 (except 1993~1996, 4 years), for 16 years, examined the relation between the dust occurrence and weather elements. Dust occurrence appeared much in spring season from March to May in study areas. It had a dry climate during that season as follows: relative humidity about 20~40%, temperature about -5~5℃, precipitation about 33~180 mm, wind speed about 4~10 ms-1. Dust occurrence and weather element annual change in study areas decreased gradually till 1990, but in Gobi desert the incidence of dust occurrence increased since 1997. As a result, found out that the more the precipitation, the less dust occurrence, because the precipitation and surface wind speed had a direct influence on the soil of the source region of dust.

The Detection of Yellow Sand with Satellite Infrared bands

Jong Sung Ha,Jae Hwan Kim,Hyun Jin Lee 大韓遠隔探査學會 2006 大韓遠隔探査學會誌 Vol.22 No.5

An algorithm for detection of yellow sand aerosols has been developed with infrared bands. This algorithm is a hybrid algorithm that has used two methods combined. The first method used the differential absorption in brightness temperature difference between 11㎛ and 12㎛ (BTD1). The radiation at 11㎛ is absorbed more than at 12㎛ when yellow sand is loaded in the atmosphere, whereas it will be the other way around when cloud is present. The second method uses the brightness temperature difference between 3.7㎛ and 11㎛ (BTD2). This technique is sensitive to dust loading, which the BTD2 is enhanced by reflection of 3.7㎛ solar radiation. First the Principle Component Analysis (PCA), a form of eigenvector statistical analysis from the two methods, is performed and the aerosol pixel with the lowest 10% of the eigenvalue is eliminated. Then the aerosol index (AI) from the combination of BTD 1 and 2 is derived. We applied this method to Multi-functional Transport Satellite-1 Replacement (MTSAT-1R) data and obtained that the derived AI showed remarkably good agreements with Ozone Mapping Instrument (OMI) AI and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth.