共查询到20条相似文献，搜索用时 31 毫秒
1.
Photosynthetically active radiation (PAR) is essential for plant photosynthesis and carbon cycle, and is also important for meteorological and environmental monitoring. To advance China’s disaster and environmental monitoring capabilities, the HJ-1A/B satellites have been placed in Earth orbit. One of their environmental monitoring objectives is the study of PAR. We simulated direct solar, scattered and environment radiation between 400 and 700 nm under different atmospheric parameters (solar zenith angle, atmospheric water vapor, atmospheric ozone, aerosol optical thickness, surface elevation and surface albedo), and then established a look-up table between these input parameters and PAR. Based on the look-up table, we used HJ-1A/B aerosol and surface albedo outputs to derive the corresponding PAR. Validation of inversed instantaneous and observed PAR values using HJ-1 Heihe experimental data had a root mean square error of 25.2 W m?2, with a relative error of 5.9%. The root mean square error for accumulated daily PAR and observed values was 0.49 MJ m?2, with a relative error of 3.5%. Our approach improved significantly the computational efficiency, compared with using directly radiation transfer equations. We also studied the sensitivity of various input parameters to photosynthetically active radiation, and found that solar zenith angle and atmospheric aerosols were sensitive PAR parameters. Surface albedo had some effect on PAR, but water vapor and ozone had minimal impact on PAR. 相似文献
2.
The high spatial resolution and temporal observation frequency of HJ-1/CCD make it suitable for aerosol monitoring. However, because of the lack of a shortwave infrared band, it is difficult to use HJ-1/CCD imagery to retrieve aerosol optical depth (AOD). We developed a new algorithm for HJ-1/CCD AOD retrieval by introducing MODIS surface reflectance outputs (MOD09) as support. In this algorithm HJ-1/CCD blue band surface reflectance was retrieved through MOD09 blue band surface reflectance by band matching of the two sensors. AOD at 550 nm was then generated through a pre-calculated look-up table for HJ-1/CCD. Eighteen HJ-1/CCD images covering the Jing-Jin-Tang (Beijing-Tianjin-Tangshan) region were used to retrieve AOD using the new algorithm, and the AODs were then validated using AERONET ground measurements in Beijing and Xianghe. The validation shows that compared with AERONET ground measurements, 27/29 AODs have error less than 0.1 in absolute value.
相似文献3.
The high spatial resolution and temporal observation frequency of HJ-1/CCD make it suitable for aerosol monitoring. However, because of the lack of a shortwave infrared band, it is difficult to use HJ-1/CCD imagery to retrieve aerosol optical depth (AOD). We developed a new algorithm for HJ-1/CCD AOD retrieval by introducing MODIS surface reflectance outputs (MOD09) as support. In this algorithm HJ-1/CCD blue band surface reflectance was retrieved through MOD09 blue band surface reflectance by band matching of the two sensors. AOD at 550 nm was then generated through a pre-calculated look-up table for HJ-1/CCD. Eighteen HJ-1/CCD images covering the Jing-Jin-Tang (Beijing-Tianjin-Tangshan) region were used to retrieve AOD using the new algorithm, and the AODs were then validated using AERONET ground measurements in Beijing and Xianghe. The validation shows that compared with AERONET ground measurements, 27/29 AODs have error less than 0.1 in absolute value. 相似文献
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5.
Letu Husi Shi Jiancheng Li Ming Wang Tianxing Shang Huazhe Lei Yonghui Ji Dabin Wen Jianguang Yang Kun Chen Liangfu 《中国科学:地球科学(英文版)》2020,63(6):774-789
The estimation of downward surface shortwave radiation(DSSR) is important for the Earth's energy budget and climate change studies. This review was organised from the perspectives of satellite sensors, algorithms and future trends,retrospects and summaries of the satellite-based retrieval methods of DSSR that have been developed over the past 10 years. The shortwave radiation reaching the Earth's surface is affected by both atmospheric and land surface parameters. In recent years,studies have given detailed considerations to the factors which affect DSSR. It is important to improve the retrieval accuracy of cloud microphysical parameters and aerosols and to reduce the uncertainties caused by complex topographies and high-albedo surfaces(such as snow-covered areas) on DSSR estimation. This review classified DSSR retrieval methods into four categories:empirical, parameterisation, look-up table and machine-learning methods, and evaluated their advantages, disadvantages and accuracy. Further efforts are needed to improve the calculation accuracy of atmospheric parameters such as cloud, haze, water vapor and other land surface parameters such as albedo of complex terrain and bright surface, organically combine machine learning and other methods, use the new-generation geostationary satellite and polar orbit satellite data to produce highresolution DSSR products, and promote the application of radiation products in hydrological and climate models. 相似文献
6.
Erythemal ultraviolet (UVER; 280–400 nm) and total shortwave (SW; 305–2800 nm) solar irradiances were recorded from 2000 to 2009 in Valladolid, Spain. UVER and SW values under cloudless conditions are simulated by radiative transfer (TUV 4.6) and empirical models. These model estimations are tested with experimental measurements showing a great agreement (root mean square error around 7%). The aerosol effect on UVER irradiance is determined through a model study. UVER radiation and total ozone column (TOC) temporal evolutions show a negative relationship. TOC accounts for 80% of UVER variance and its radiation amplification factor is 1.1 at zenith of 65°. Cloud effects on solar radiation are shown and quantified by the cloud modification factor. Moreover the enhancement effect cases are analysed. SW radiation proves more sensitive to clouds than UVER. Clouds are seen to attenuate and enhance solar radiation by up to 93% and 22% in the UVER range, respectively. 相似文献
7.
Previous work has shown the importance of the diffuse solar field in the photochemistry of atmospheric active species, the solar zenith angle being an effective parameter. In view of the diurnal and seasonal variability of this single quantity, in this paper estimates are presented of the daily-integrated values of the photodissociation coefficient of ozone throughout the year, for a purely molecular atmosphere in the absence of scattering and when the effects of molecular scattering are included, and for an absorbing-scattering turbid atmosphere characterized by two different aerosol loads. Also, different values of the ground albedo have been taken into account.Results are shown for a latitude of 45oN. The seasonal dependence is strong at altitudes below 20 km and less marked above 20 km. For an albedoA=0.3, the inclusion of molecular scattering increases the daily-integrated photodissociation coefficients approximately by 20% and 40% at 15 km and by 15% and 22% at 30 km, at the winter and summer solstice respectively. The presence of a heavy aerosol load modifies these results by a further factor which is approximately –5% and 10% at 15 km at the winter and summer solstice respectively, and is approximately constant at 8% throughout the year at 30 km. 相似文献
8.
An algorithm based on simulated satellite signal calculated by the 6S radiative transfer model has been developed in order to retrieve the aerosol optical thickness of dust over the Atlantic ocean. The algorithm is applied to the visible channel of Geostationary Operational Environmental Satellite (GOES 8) images. The inversion uses a look-up table giving the satellite signal intensity as a function of surface albedo, viewing geometry, solar illumination and the optical properties of the aerosols. The study consists of assessing the feasibility of monitoring and mapping the transport of suspended particles across the Atlantic from the Sahara to the Caribbean. The study area is between 10 and 25 N and 30 and 65 W. The optical thickness of aerosols has been calculated over a period of 11 days between 10th and 20th of June 1997 for the 14:15 UT GOES image acquisition. The calculated aerosol optical thickness ranges from 0.0 to 0.81 with an important event of dust presence occurring between 13th and 16th of June. The retrieved aerosol optical thickness is in good agreement with the values obtained between 14h UT and 15h UT from ground based sun photometer measurements on the island of Guadeloupe, and a coefficient correlation (R2) of 0.88 has been found between the data sets. 相似文献
9.
《Journal of Atmospheric and Solar》2000,62(8):629-638
Factors affecting UV radiation at the earth’s surface include the solar zenith angle, earth–sun distance, clouds, aerosols, altitude, ozone and the ground’s albedo. The variation of some factors, such as solar zenith angle and earth–sun distance, is well established. Total column ozone and UV radiation are inversely related, but the presence of clouds may affect the resulting UV in such a way that a depletion in the total column ozone may not always lead to an increase in the radiation at the earth’s surface. The aim of this paper is to determine the contribution to the variation of the biologically effective irradiance by geometric factors, clouds and ozone, jointly and separately, in Ushuaia (54°49′S, 68°19′W, sea level), and the seasonal variation of this relationship, given the magnitude and seasonal distribution of the ozone depletion and the frequent presence of high cloud cover in this site. For this purpose, multivariate and simple regression analyses of daily and monthly integrated irradiances weighted by the DNA damage action spectrum as a function of total column ozone and the integrated irradiances in the band 337–342 nm (as a proxy for cloud cover and geometric factors) have been performed. For the analysed period (September 1989–December 1996) more than 97% of the variation of the DNA damage weighted daily integrated irradiances is described by changes in ozone, clouds and geometric factors. Simple regression analysis for daily integrated irradiances, grouped by month, shows that most of this variation is explained by clouds and geometric factors, except in spring, when strong ozone depletion occurs intermittently over this area. When monthly trends are removed, similar results are observed, except for late winter. 相似文献
10.
本文利用大气环流模式及大气化学模式所得气溶胶资料,估算了相对1850s时期硫酸盐和黑碳气溶胶引起的全球及东亚区域人为辐射强迫,重点分析其在东亚区域的季节和长期变化特征.结果表明,就当前全球年平均全天空而言,人为硫酸盐气溶胶对大气顶的直接和云反照率强迫分别为-0.37和-0.98 W·m-2,黑碳气溶胶对大气顶和整层大气的辐射强迫值为0.16和0.47 W·m-2;中国东部区域是目前上述气溶胶辐射强迫最强的区域,硫酸盐的直接和间接辐射强迫分别超过-2.0和-4.0 W·m-2,黑碳对大气顶和整层大气的直接辐射强迫分别可达2.0和5.0W·m-2;估算的东亚区域上述气溶胶辐射强迫仍在不断增强,峰值预计出现在2010s时段,而且中国东部较强的辐射强迫还可能维持至2030s左右;在未来中、高排放情景下,东亚区域以上两种气溶胶预计对全球气溶胶辐射强迫有更大的贡献.分析还表明,夏季东亚区域较强的水汽会增强吸湿性硫酸盐气溶胶的光学厚度和晴空直接辐射强迫;云的作用一方面会强化东亚区域全天空条件下大气顶黑碳的辐射强迫,另一方面会影响硫酸盐气溶胶间接云反照率强迫的季节变化;上述气候特征的差异使得东亚区域的气溶胶辐射强迫表现出与欧美区域有所不同的特征.本文所用的气溶胶资料与模式气象场的偏差会给气溶胶辐射强迫计算带来一些不确定性,进一步改进气候模式中气溶胶过程、水汽和云等气象场的模拟将有助于获得更为合理的区域气溶胶辐射强迫估算结果. 相似文献
11.
Continuous measurements of solar spectral radiation using the Multi-filter Rotating Shadow Band Radiometer (MFRSR) are performed at the Actinometric Station of the National Observatory of Athens (ASNOA). The present study utilizes three clear-sky days of continuous observations, from local sunrise to local sunset, in order to investigate the daily variation of the radiation components (diffuse, global and direct-beam) as well as their ratios (diffuse-to-global, DGR, and diffuse-to-direct-beam, DDR) under different atmospheric conditions. Both ratios have received great scientific interest, especially for investigating solar irradiance modifications under various atmospheric conditions, aerosol load and optical properties. Apart from this, the present study shows that the DDR can constitute a measure of atmospheric turbidity when it is determined at longer wavelengths, while the DGR cannot. The effect of the solar zenith angle (SZA) on both ratios is significant at the shorter wavelengths with varying sensitivities depending on the aerosol field and sun elevation. The present study confirms the results obtained by previous solar irradiance measurements in Athens and also those computed via radiative transfer codes and sheds light on the scientific knowledge of the use of spectral DDR as an atmospheric turbidity index. 相似文献
12.
K.V.S. Badarinath Shailesh Kumar Kharol Anu Rani Sharma 《Journal of Atmospheric and Solar》2009,71(1):112-120
Agriculture crop residue burning in tropics is an important source of atmospheric aerosols and monitoring their long-range transport is an important element in climate change studies. Synchronous measurements using micro-pulsed lidar, MICROTOPS-II sun photometer, multi-filter rotating shadow band radiometer (MFRSR) on aerosol optical depth and ground reaching solar irradiance were carried at an urban location in central region of India. Aerosol backscatter profiles obtained from micro-pulse lidar showed elevated aerosol layers up to ～3 km on certain days during October 2007. Satellite data observations on aerosol properties suggested transport of particles from agriculture crop residue burning in Indo-Gangetic Plains over large regions. Radiative forcing of aerosols estimated from SBDART model with input information on aerosol chemical properties, aerosol optical depth and single scattering albedo and broadband solar irradiance measurements using MFRSR showed good correlation (R=0.98). 相似文献
13.
Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l.), an inland location. The database includes hourly values of the relevant variables covering the years 1994/95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290/385 nm). After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those considered as urban. Although SMARTS2 provide slightly worse results, both models give estimates of solar ultraviolet irradiance with mean bias deviation below 5%, and root mean square deviation close to experimental errors. 相似文献
14.
Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed. 相似文献
15.
Based on light-use efficiency model, an MODIS-derived daily net primary production (NPP) model was developed. In this model, a new model for the fraction of photosynthetically active radiation absorbed by vegetation (FPAR) is developed based on leaf area index (LAI) and albedo parameters, and a pho- tosynthetically active radiation (PAR) is calculated from the combination of Bird's model with aerosol optical thickness and water vapor derived from cloud free MODIS images. These two models are inte- grated into our predicted NPP model, whose most parameters are retrieved from MODIS data. In order to validate our NPP model, the observed NPP in the Qianyanzhou station and the Changbai Mountains station are used to compare with our predicted NPP, showing that they are in good agreement. The NASA NPP products also have been downloaded and compared with the measurements, which shows that the NASA NPP products underestimated NPP in the Qianyanzhou station but overestimated in the Changbai Mountains station in 2004. 相似文献
16.
This work investigates the spectral atmospheric transmittance due to aerosols in the urban environment of Athens during a period of one year. The spectral transmittance due to aerosols is derived using measurements of spectral direct-beam solar irradiance in the 310–575 nm spectral band. This derivation is accomplished by using a radiative transfer model for estimating the partial spectral atmospheric transmittance functions due to Rayleigh scattering, and absorption by ozone, nitrogen dioxide and water vapor. The seasonal and diurnal variation of the aerosol transmittance is investigated and the results are discussed with a view to air pollution sources, meteorological factors and topographic characteristics of the Athens basin. 相似文献
17.
基于太湖气溶胶类型分区的环境一号卫星CCD大气校正 总被引：1，自引：0，他引：1
由两颗卫星组成的环境卫星星座系统所提供的CCD数据具有较高的时间分辨率,使其在内陆湖泊水环境遥感监测中具有较大的应用潜力,对其有效的大气校正方法的研究则是其定量化参数反演的前提.基于准同步的MODIS数据辅助,根据气溶胶的差异性,将太湖划分为北部湖区、其他湖区两块区域,利用辐射传输模型,研究太湖环境一号CCD数据大气校正的方法,并对2009年4月17、21、25日数据进行大气校正.研究结果表明,该大气校正方法直接使用较为成熟的MODIS各类产品,克服了传统大气校正中依赖于现场同步测量大气参数的缺陷,能够快速、有效地完成环境一号CCD数据的大气校正.基于气溶胶类型对太湖进行分区后,所求算的遥感反射率精度高于6S模型和暗像元等大气校正方法得到的结果. 相似文献
18.
We simulated geostationary satellite observations to assess the potential for high spatial-and temporal-resolution monitoring of air pollution in China with a focus on tropospheric ozone(O_3), nitrogen dioxide(NO_2), sulfur dioxide(SO_2), and formaldehyde(HCHO). Based on the capabilities and parameters of the payloads onboard sun-synchronous satellites, we simulated the observed spectrum based on a radiative transfer model using a geostationary satellite model. According to optimal estimation theory, we analyzed the sensitivities and retrieval uncertainties of the main parameters of the instrument for the target trace gases. Considering the retrieval error requirements of each trace gas, we determined the major instrument parameter values(e.g., observation channel, spectral resolution, and signal-to-noise ratio). To evaluate these values, retrieval simulation was performed based on the three-dimensional distribution of the atmospheric components over China using an atmospheric chemical transportation model. As many as 90% of the experiments met the retrieval requirements for all target gases. The retrieval precision of total-column and stratospheric O_3 was 2%. In addition, effective retrieval of all trace gases could be achieved at solar zenith angles larger than 70°. Therefore, the geostationary satellite observation and instrument parameters provided herein can be used in air pollution monitoring in China. This study offers a theoretical basis and simulation tool for improving the design of instruments onboard geostationary satellites. 相似文献
19.
沙漠地区植被稀疏、干旱少雨,其陆面物理过程具有与全球其它地区显著不同的特点.本文利用巴丹吉林沙漠观测资料,分析和计算了地表反照率、比辐射率、粗糙度和土壤热容量、热传导系数等关键陆面过程参数,建立了适合于沙漠地区的陆面过程模式DLSM (Desert Land Surface Model),并与NOAH陆面过程模式的模拟结果和观测资料进行了比较.结果表明:巴丹吉林沙漠地表反照率为0.273,比辐射率为0.950,地表粗糙度为1.55×10-3 m,土壤热容量和热扩散系数分别为1.08×106 J·m-3·K-1和3.34×10-7 m2·s.辐射传输、感热输送和土壤热传导过程是影响沙漠地区地表能量平衡的主要物理过程.通过对这三种过程的准确模拟检验,DLSM能够较准确地模拟巴丹吉林沙漠地气能量交换特征;短波辐射、长波辐射和感热通量的模拟结果与观测值间的标准差分别为7.98,6.14,33.9 W·m-2,与NOAH陆面过程模式的7.98,7.72,46.6 W·m-2的结果接近.地表反照率是沙漠地区最重要的陆面过程参数,地表反照率增大5%,向上短波辐射通量随之增加5%,感热通量则减小2.8%.本文研究结果对丰富陆面过程参数化方案,改进全球陆面过程模式、气候模式具有参考意义. 相似文献
20.
Stream surface albedo plays a key role in the energy balance of rivers and streams that are exposed to direct solar radiation. Most physically based analyses and models have incorporated a constant stream albedo between 0.03 and 0.10, based primarily on measurements from low‐gradient streams with low suspended sediment concentrations. However, albedo should vary with solar elevation angle, suspended sediment concentration, aeration, and fraction of direct versus diffuse radiation. The objective of this study was to quantify the dependence of albedo of mountain streams on the controlling factors and to develop a predictive model for use in physically based analysis and modelling of stream temperature, especially for future climate and land‐use scenarios. Stream surface albedo was measured at nine sites with a variety of gradients and suspended sediment characteristics in the southern Coast Mountains of British Columbia, Canada. As expected, albedo of low‐gradient, non‐white water (flatwater) streams increased with solar elevation angle, suspended sediment concentration, and proportion of diffuse to direct solar radiation, ranging between 0.025 during cloudy periods over clear water to 0.25 for turbid water at elevation angles of less than 20°. Albedo was enhanced in steep reaches or at channel steps and cascades where flow was visibly aerated, with a range of 0.09 to 0.33. In clear weather, albedo exhibited notable diurnal variability at flatwater sampling sites. For example, during late summer, surface albedo typically fluctuated between 0.08 and 0.15 on a daily basis at a flatwater site on the highly turbid, glacier‐fed Lillooet River. Multiple regression models explained approximately 60% and 40% of the variance under cross validation for flatwater and white water data subsets, respectively, with corresponding root mean square errors of approximately 0.02 and 0.06. 相似文献