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Ⅲ. 雲・エアロゾルの光学的特性とその応用, エアロゾルや雲の放射影響評価を地上観測によって明らかにする目的で, SKYNETが構築された. SKYNETは, 観測ネットワークをベースとした, 観測データ及び解析結果の共有, 観測・解析手法の開発などを行うオープン研究コミュニティである. 基幹機材であるスカイラジオメータ（POM-01, POM-02）の観測・解析を中心に, SKYNETではデータ品質の統一と向上を図るための努力が, 観測・解析の両面で行われている. SKYNETで観測されるエアロゾルは, それぞれの地域の特徴としてまとめられると同時に, 衛星によるエアロゾルプロダクトの検証にも利用され, その一例を示した. こうした研究では, 衛星データ解析による幾つかの仮定の妥当性が検証され, アルゴリズムの改善に役立てられる. SKYNETの重要拠点では, ライダーを利用した鉛直分布計測や散乱計, 吸収計を利用した直接サンプリングも並行して行われている. こうした多様なデータは, 複合的な解析を通してより精確な描像を得るのに有用である. SKYNETによる地上からの雲計測は, スカイラジオメータ（POM-02）を主として, その他に雲カメラ, マイクロ波放射計などが重要拠点で実施されている. 雲計測のポイントは雲の非均質性にあり, 新しい観測・解析手法を含めて, 放射影響評価のための努力がなされている., The SKYNET is an open research network for observation to estimate the radiative effects of aerosol and cloud in the atmosphere. The research community can share the observed data and the analyzed results in the SKYNET as well as these methods, and has been making efforts to improve the data quality in terms of observation and analysis. Aerosol parameters derived in the SKYNET activities are compiled as optical features in each region, and also utilized for the validation of satellite products. An example is shown in the satellite validation to improve the retrieval algorithm. In-situ sampling instruments such as a nephelometer, absorption meter, etc are operated as well as a lidar to get an aerosol vertical profile in several super sites of the SKYNET. Through the comprehensive analysis of these data, the understanding of the optical characteristics of aerosols makes progress. Cloud observation in the SKYNET is also performed using a sky radiometer (POM-02) mainly, and in addition, a sky-viewing camera, a microwave radiometer and related instruments working in some super sites. The most sensitive issues on cloud observation are inhomogeneity in time and space. The SKYNET community has been making efforts to make it clear in viewpoint of radiative effects of clouds including developments of observation and analysis methods.

Ⅳ. リモートセンシングで観るエアロゾル・雲相互作用, 地球温暖化に影響を与える高層の薄い雲を調べるには, 周波数の高い電波を用いるレーダによる観測が適している. 気象観測でこれまでに使用されている最も高い周波数95GHzを用いた千葉大学ミリ波雲レーダFALCON-Iは, 高い感度と空間・時間分解能を備えている. FALCON-Iの概要と観測例, 雲底からの降雨が約200m落下して終端速度の到達する様子, 積乱雲の発達過程で上昇する雲の内部運動速度幅が10m/sに達している様子, 衛星搭載雲レーダとの同時観測で良い一致を示す例, などの結果を示し, 今後の展望を概観する., Observation of clouds using high frequency radars is one of powerful methods for investigating thin and high-altitude clouds,which affect greenhouse effect. FALCON-I is a millimeter wave cloud profiling radar of Chiba University at 95 GHz, which is the highest frequency for normal meteorological use and has high sensitivity and spatial-, temporal-resolution. The system of FALCON-I and examples of observations are presented;accelerating rain drops to the terminal velocity in about 200m from the cloud bottom,Doppler velocity width reaches 10 m/s in cloudlets in ascending phase of a cumulonimbus, good correspondence of cloud profiles obtained FALCON-I and satellite observations, and so on. Future developments of FALCON are also mentioned.

[ABSTRACT]With the aim of better understanding the optical characteristics of the East Asian aerosols and their climatological impacts, we analyzed multiyear data collected at typical sites of SKYNET network that represent aerosols of different origins and backgrounds. Aerosol optical parameters and their climatic impacts in the urban areas were observed to vary spatially and temporally having different values of aerosol optical parameters and heating rate. This study suggests that the Asian dust aerosols near the source region may have weak light absorption capacity and weak heating rate. For the study conducted in biomass burning active area, we noted the existence of optically thicker small size ranged aerosols having signification contribution in aerosol heating rate during biomass burning season. By analyzing data collected at the East China Sea region, the study suggests that, especially in the spring season, air masses from the arid and urban regions of the Asia may transport aerosols of different origins to cause the aerosols of this region optically thicker and more light absorptive in nature that can have strong heating rate.

[ABSTRACT]Observations of tropospheric aerosols using a ground-based network of two-wavelength (532nm, 1064nm) polarization (532nm) lidars (SKYNET-lidar < NIES Lidar Network < AD-Net < GALION) are reported. Currently, the lidars are continuously operated at 18 locations in East Asia, including 3 stations in Mongolia, Seoul, Korea, and Phimai, Tailand. The data from the lidars in the network are transferred to the National Institute for Environmental Studies (NIES) in real time and processed to derive the attenuated backscattering coefficients at the two wavelengths and the volume depolarization ratio. The extinction coefficient estimates for non-spherical aerosols (dust) and spherical aerosols are also derived automatically with the real-time data processing system. The data from the network are used in various studies on atmospheric environment and climate change. In this paper, we report on the lidar instrument and the network, the data analysis methods for estimating aerosol components, and the results of recent studies on Asian dust, air pollution aerosols, and forest fire smokes. The role of the lidar network in the GAW Aerosol Observation Lidar Network (GALION) and the role of GALION in climate change studies will be also discussed.

[ABSTRACT]Collocated observations of aerosol optical parameters, radiative fluxes in the longwave (0.4-50μm) and shortwave (0.3-3 μm) spectral regions were used to quantify aerosol radiative forcing in the longwave (LW) and shortwave (SW) spectral regions over an Indian urban site, Pune during October 2004 to May 2005. Aerosol optical parameters derived from a Prede Sun/Sky radiometer such as aerosol optical depth (AOD), single scattering albedo, asymmetry parameter, TOMS column ozone and MODIS water vapor were used in Santa Barbara Discrete ordinate Rdaitive Transfer model (SBDART) to derive short and long wave radiative fluxes. Short wave fluxes were found to be comparing well with the real time observed fluxes from a Short wave Pyranometer. The under estimation of modeled long wave fluxes got improved and found to be comparable with observed fluxes from a Precision infrared radiometer, on the inclusion of six hourly NCEP profiles of temperature and humidity in SBDART model. ‘No aerosol’ fluxes were also derived using SBDART in both the spectral region. The differences in fluxes with and without aerosol conditions were calculated to derive radiative forcing. The short wave radiative forcing during different seasons viz. Post monsoon (October, November), winter (Dec-Feb) and Pre-monsoon (March- May) respectively found to be -36, -33 and -44 Wm-2 at the surface and +0.5,-0.55, +0.4 Wm-2 at the Top of the Atmosphere (TOA) . The corresponding long wave enhancement found to be +8.5, +8, +10.5 Wm-2 at the surface and, +3.5, +3 and +4.7 Wm-2 at TOA. The study suggests that around 23-25% of aerosol cooling in the short wave region is being compensated by long wave enhancement at the surface.

[ABSTRACT]Aerosols play an important role in the global climate, the radiative forcing of the climate, and the Earth's radiative balance. The aerosols were measured at the Observatory of Atmospheric Research, in Phimai, Thailand where is a member of SKYNET, during 2006-2008. The amount aerosols were much higher in the dry seasons than in the wet seasons due to monsoon. The aerosols were collected during 2007-2008 and the records of fine particles found that ammonium sulfate, and elementary and organic carbons were major components especially in dry season. Aerosol optical depth by sky radiometer was about 0.90 in wet seasons, and much higher than in the dry seasons. In dry season were many fires activity due to the biomass burning from agricultural harvest almost all over Thailand. These results clearly indicate that the aerosols emitted from biomass burning could affect on atmospheric.

[ABSTRACT]Aerosol radiative properties are retrieved from the observed data using a ground based sky radiometer. The seansonal variations are discussed after a good validation using another sunphotometer. The derived results as input parameters are used to calculated aerosol radiative forcing (RF). The comparison between the measured flux and the modeled flux shows a good agreement at the surface. The mean values of RF due to aerosol at SFC, TOA, and in ATM during 2007 to 2010 are -33.9, -23.1, and 10.8 Wm-2, respectively. Because of high value in SSA, the relative RF kept in ATM is not so much though the large value of AOD over Hefei.

[ABSTRACT]This study presents a method to retrieve key aerosol optical parameters such as aerosol optical thickness and single scattering albedo using spectral direct and diffuse irradiances measured at surface by taking into account the cosine error correction factors in detail. The proposed method is applied to observed spectral irradiance data at Hedo observation site of SKYNET network. We found very good agreement for aerosol optical thickness and reasonable agreement for single scattering albedo with results from sky radiometer.

[ABSTRACT]This study investigates the characteristics of dust aerosols over Loess Plateu of Northwest China using observation data collected in this region during 2009 and 2010. As the first part of the research, comparison of aerosol optical thickness (AOT) and single scattering albedo (SSA) measured by two independent instruments (SKYNET sky radiometer and AERONET sun photometer) is performed. We find very good agreement of AOT, whereas SSA from the former instrument is systematically higher than the latter on. The possible reasons for such differences are discussed. As the second part of the study, we study the characteristics of dust aerosols in this region. We find that strong dust events can carry high concentration of anthropogenic aerosols, such as black carbon (BC) aerosol, during their transport from the source region. This finding may provide some clues to justify absorptive Asian dust aerosols observed in the Pacific Ocean region in the past studies. The study also suggests that significant dust aerosols may exist in the atmosphere of this region even during no dust event days.

[ABSTRACT]Aerosol optical characteristics observed by a POM-01 sky radiometer over Loess Plateau in China during the period from March 15th to October 31th 2009. A good agreement was implemented by the improved Langley method. The measured and retrieved AOD from the PREDE sky radiometer are very consistent with the measured by Cimel sunphotometer’s results. We find that the daily average values of AOD500 and ?ngstr?m exponent ( α ) both show very large day-to-day variations, especially during the springtime. The relationship between AOD500 and ?ngstr?m exponent shows obvious negative correlation during the whole period. Dust aerosol particles are dominant during springtime at SACOL, and fine mode particles are predominant during summertime due to the impact of the rainy season.

[ABSTRACT]The quality of Earth observation satellites’ products can be evaluated through the comparison of these quantities with those derived from ground measurements. In the perspective of the operational start of the Global Change Observation Mission-Climate (GCOM-C) satellite carrying the Second-generation Global Imager sensor (SGLI) , the quality of aerosols properties retrieved from actual and comparable satellites, such as the Terra- and Aqua- Moderate Resolution Imaging Spectroradiometer (Terra- and Aqua-MODIS), is assessed with ground measurements from three SKYNET (observation network to understand aerosol-cloud-radiation interaction) sites, located in the southern part of Japan. In this assessment, two major aerosols properties, the aerosol optical thickness (AOT) and the ?ngstr?m exponent (Alpha), derived from skyradiometers measurements of the SKYNET sites are compared with the retrievals from two Terra- and Aqua-MODIS satellites’ algorithms for a period of 2 years (2008 and 2009). Results of these comparisons show overall similarities in the monthly and seasonal variations of the aerosols quantities between these data sets. However the magnitude of this variation shows some differences between the ground data and one of the MODIS algorithms. The retrievals from this algorithm appear consistently overestimated for the AOT (thicker layers) and underestimated for Alpha (dominance of coarser particles). Possible causes of these tendencies are investigated with particular emphasis on the aerosol size distribution assumption used for the satellite retrievals and the contamination by clouds.

[ABSTRACT]SW radiation budget is estimated using geostationary satellites (GMS-5, GOES-8, GOES-10, METOSAT-5, METEOSAT-7). Each satellite data are calibrated, and optics properties of the cloud are retrieved. An accurate calibrated data propose the better accuracy for analysis of cloud and radiation budget. In this study, cloud and SW radiation budget analysis are done by CAPCOM algorithm and EXAM SYSTEM. On the other hand, aerosol optical thickness is retrieved by L-REAP algorithm. We discuss the possibility of aerosol-cloud-radiation interaction in north Pacific ocean and north Atlantic ocean.

[ABSTRACT]High resolution Doppler Observations of clouds have been done with the millimeter-wave cloud profiling radar (CPR) FALCON-I developed at Chiba University. FALCON-I operated at 95 GHz has a high spatial resolution of 15 m in the ranging direction and of 0.2°in the perpendicular directions. Precise observations of melting layers at the bottom of clouds reveal that rain drops whose diameters would be around 1 mm are generated and accelerated up to 7 m/s downward in quite thin layer of about 200 m. Doppler Observations of interior of cumulonimbus suggest existence of small structures of about 1 km in which abrupt up and downward flow occurs. These results will be useful to investigate characteristics of clouds in various places and oceans in order to make global model of atmosphere.

[ABSTRACT]CPR (Cloud Profiling Radar) is expected to reveal the inside structure of clouds. Using vertical profiles of radar reflectivity factor, vertical profiles of cloud microphysical properties (e. g., cloud effective radius, liquid water content, cloud optical depth) can be retrieved with data of other instruments, which leads to better understanding of cloud radiative forcing and the earth's energy balance. Chiba University has developed the solid-state ground-based FMCW CPR FALCON-I to achieve higher range and time resolution with lower power. In this study, sensitivity and accuracy of FALCON-I are evaluated at the Hedo observation in 2008.

[ABSTRACT]In this study, we develop a vicarious calibration technique and estimation algorithm of radiation budget for the global analysis. The vicarious calibration technique using three components ( clear sky sea surface, clear sky land surface, uniform cloud top) is applied to the geostationary satellites. This vicarious calibration technique is based on radiative transfer calculations and it has each optical properties (aerosol, cloud, surface BRDF/albedo) in three compon_~ntsT. he quality of three geostationary satellites (GMS-5, GOES-10, GOES-8) visible channel fixed accurately for global analysis. An accurate calibrated data set propose the better accuracy for analysis of cloud and radiation budget. Thus, cloud and radiation budget analysis algorithm are applied to new calibrated data set for global analysis. This is first result of trial for global analysis.

[ABSTRACT]The long-term changes in the radiation budget of the East Asia region and related atmospheric parameters have been investigated in a comprehensive manner, employing both the satellite data and ground-network data. Through the recent activities of this project, new algorithms have been developed and tested for extracting various atmospheric parameters from satellite data. Simultaneous observations with ground instruments, including a network observation called SKYNET, are used for validation as well as improvement of the algorithms. Regional and seasonal variations of aerosol, cloud, and radiation amounts have been studied.

資料番号: PA0810113000

[ABSTRACT]The re-construction of the GMS-5 visible channel calibration table is examined. It is based on the comparison of satellite observation with reference. To obtain the reference, satellite radiance is simulated over various reference targets of clear sea area, clear land area and cloud top as dark, medium and bright references, respectively. Parameters necessary to compute the radiance are prepared independently from GMS-5 observations. The recalibrated visible table improves the GMS-5 data. That is confirmed from the improvement of aerosol and cloud products retrieved from the GMS-5 data.

[ABSTRACT]A retrieval algorithm of vertically integrated water vapor amount (precipitable water) over land was applied to the near infrared data of Global Imager onboard Advanced Earth Observing Satellite-II (GLI / ADEOS-II). Comparing the retrieved precipitable water with radiosonde observation, we had some underestimation with some systematic bias for larger water vapor amounts in a preliminary analysis. Accordingly, we re-evaluated a relationship between radiance to be observed with GLI and water vapor amount, carrying out more detailed radiative transfer simulations. The retrieved water vapor amount with the coefficients was compared to radiosonde observation and ground-based microwave radiometer measurements. As a result of the validation, we have a relative error of about 30% and 10%, respectively. It also turns out that the linearity is quite good between the precipitable water with GLI and that with the radiosonde or microwave radiometer observation. Further, it is necessary to compare the satellite-retrieved results with the skyradiometry on a local basis as well as other satellite products on a global basis.

[ABSTRACT]Net long-wave radiation is an important component of radiation budget. The knowledge of induced factors (such as water vapor, aerosol) of radiation budget provides an opportunity for understanding the impact of environmental changes on climate. Utilizing the radiation data observed by pyrgeometer at definite times every day from 2003 to 2007 at SKYNET Hefei site in East China, the characteristic of net long-wave radiation over grassy land is discussed on 293 clear days. Meanwhile, based on these five years observations of integrated water vapor by microwave radiometer WVR-1100, variability of the atmospheric water vapor on sunny days has been statistically analyzed. And the aerosol optical property in the corresponding period is also obtained by an automated two wavelength (1064nm, 532nm) polarization (532nm) lidar. For the value of integrated water vapor, validation is given by a local radiosonde and good agreement is shown. As to the lidar dataset, we apply the Femald's method to derive the extinction coefficient. The profile of aerosol extinction coefficient is compared with anther lidar system PML and indicates great agreement. Then the AOD under the height of 3 km is calculated by layer-integrated extinction coefficient. This study mainly addresses the daily and seasonal variations of net long-wave radiation, integrated water vapor and AOD as well. We attempt to characterize the optical property of aerosol and the value of integrated water vapor and their effects on the net long-wave radiation over Hefei. The results show that some certain negative correlations are considered to occur between the latter two kinds of factors and the net long-wave radiation. And especially in summer the effects of water vapor and the aerosol on net long-wave radiation are very obvious. Large water vapor and aerosol loading lead to a very low net long-wave radiative effect.

[ABSTRACT]In this study, we analyze Refined -Visible and Infrared Spin-Scan Radiometer (R-VISSR) data set. An accurate calibrated data propose the better accuracy for analysis of cloud and radiation budget. Therefore, in Asian Atmospheric Particle Environmental Change Studies (APEX) -E2 period, diffuse component and aerosol optical thickness showed the pattern that looked like well. Thus, analysis of 12 months of 2001 was executed that the results indicate a feature trend of the direct and the diffuse component of downward solar radiation from East Asia to North Pacific Ocean. Moreover, contrast is clear between East Asia and South side of Australia in direct and diffuse components.

[ABSTRACT]This paper firstly describes an algorithm to screen cloud-affected data for sky radiometer data analyses. The proposed algorithm is observed to screen cloud-affected more effectively in comparison to other algorithms. Secondly, aerosol climatologies in an urban atmosphere of Chiba studied by using cloud-screened data are presented. Aerosols in an urban atmosphere of Chiba are observed to show distinct seasonal variations in magnitudes and diurnal cycles of optical properties as well as magnitudes of aerosol radiative forcing. The study suggests the influence of complicated air masses in the spring season, whereas aerosols existing in the autumn season are suggested to be more capable to trap energy in the atmosphere by creating comparatively larger radiative forcing efficiency difference at that top of the atmosphere and the surface.