太阳紫外辐射在大气中衰减的探讨

在对北京紫外辐射观测资料分析的基础上,提出了参与光化学反应的物质对太阳紫外辐射能量的吸收作用.计算表明北京地区1990年云天比晴天紫外辐射减少约为21W m-2,此值与CeSS等人的观测结果比较接近.这表明了大气中参与光化学反应的物质对光化辐射能量的吸收基本上等于云对太阳短波辐射的"异常吸收"之值.所以,在辐射传输模式、大气化学模式、气候模式中,应该考虑参与光化学反应的物质对光化辐射能量的吸收作用.     

Ultraviolet sky radiance distributions of translucent overcast skies

Summary The diffuse sky radiation component in the ultraviolet wavelengths is often at least 50% of the global irradiance under clear skies, and is the dominant component of ultraviolet global radiation under translucent overcast skies. The distribution of sky radiance was measured in a rural area and modeled for wavelength bands of ultraviolet-B (UVB, 280–320 nm) and ultraviolet-A (UVA, 320–400 nm). Sky radiance measurements were made during the summer of 1993 over a wide range of solar zenith angles using radiance sensors mounted on a hand-operated hemispherical rotation mount. UVB irradiance measurements were also made during each scan. Since the ratio of measured irradiance under overcast skies and that predicted for clear skies was not correlated with cloud base height, opaque cloud fraction, or solar zenith angle, it was concluded that the scattering from the clouds dominated the global irradiance, and this scattering was relatively unaffected by the scattering off opaque clouds in the translucent atmosphere.Analysis of the translucent overcast sky UVA and UVB radiance measurements using a semi-empirical distribution model showed that the spectral influences on multiple scattering, single scattering, and horizon brightening components of the distributions agreed with basic atmospheric radiation theory. The best model used solar zenith, the sky zenith, and the scattering angle with resultant coefficient of determination values of 0.62 and 0.25 for the UVA and UVB respectively. The developed equations can be applied directly to the diffuse sky irradiance on the horizontal to provide radiance distributions for the sky.With 6 Figures     

北京城市紫外辐射变化特征及经验估算方程

利用2004年4月—2005年6月在中国科学院大气物理研究所铁塔分部的紫外辐射观测数据,分析了北京城市紫外辐射的变化特征,结果表明,紫外辐射的变化规律与太阳总辐射一致,紫外辐射与总辐射的比值变化范围在0.02~0.04之间,晴天恒定在0.03,阴天在0.04左右,在沙尘暴过程中比值最小,为0.02。通过分析紫外辐射与大气质量数和平均晴空指数之间的关系,建立了适合于北京的全天候紫外辐射的估算方程。利用建立的估算方程及观测的总辐射值进行了紫外辐射的估算,紫外辐射的计算相对误差在10%以内。     

阿尔卑斯山杉林冠层影响辐射传输的个例分析

利用瑞士Alptal观测站杉树林冠层上方、下方的辐射观测资料,分析了冠层对短波辐射的减弱及对长波辐射的增幅作用及其季节变化。结果表明,对比较密集的常绿针叶林,冠层对入射短波辐射的透过率随着太阳高度的降低而减小,春季以后趋于稳定;冠层对长波辐射的增幅作用随天气状况而变化,这种增幅作用在晴空条件下最显著,可达1.5倍。在冬季,因为太阳辐射较弱,冠层对长波辐射的增幅作用超过对短波辐射的减弱从而增加地面净辐射。在其它季节,太阳辐射比较强,冠层对短波辐射的减弱超过对长波辐射的增幅作用而减少地面净辐射。地面净辐射与冠层上方气温的变化趋势虽然在有些时段一致,但在伴随降雪过程的降温时段,地面净辐射与气温的变化趋势近乎反相,在积雪融化时段,地面净辐射的增加比气温升高更显著,尤其是在白天。     

Observation and Simulation of Abnormal Transmittance over Yangbajing,Tibet

Defining abnormal transmittance as the case where the magnitude of the shortwave flux transmittance is greater than 1.0, the authors used surface solar irradi- ance and all-sky images obtained at the Yangbajing site in Tibet to analyze the reasons for the occurrence of abnor- mal shortwave flux transmittance. Based on the Interna- tional Intercomparision of Three-Dimensional Radiation Code （I3RC） Monte Carlo community model of three-dimensional radiative transfer, the authors also per- formed simulations at a nonabsorbing wavelength and an absorbing wavelength through a stratocumulus and a cu- mulus field. The results showed the detection of abnormal transmittance on more than half the days, and the maxi- mum transmittance was 1.34. The probability of the oc- currence of abnormal transmittance appeared to be largest in summer, and on a daily basis was mainly at about noon local time. Abnormal transmittance mainly appeared when clear sky and clouds co-existed, especially at the edges of broken clouds and nearby regions with clear-sky conditions. The flux transmittance decreased as the solar zenith angle increased.     

韶关地区太阳能资源分析与评估

根据1981-2015年广州、韶关等9站气象观测资料,采用气候学统计、线性趋势分析和有关行业标准等,对韶关地区太阳能资源分布特征进行了分析评估。结果表明:近35年来,韶关地区属于太阳能资源丰富区,年太阳总辐射的线性变化趋势不显著;夏季辐射丰富,冬季偏少;月平均总辐射7月最多,2月最少;年总辐射仁化最多,乐昌最少。年日照时数的线性变化趋势也不显著;夏季日照时数多,春季的少;月平均日照时数7月最多,3月最少;年日照时数也是仁化最多,乐昌最少。日照时数6 h的平均天数为139.6天,太阳能资源利用价值一般,但7-12月太阳能资源利用价值较高。月最大日照时数7月6 h的天数为18.2天,是月最小日照时数3月的3.96倍,太阳能资源较稳定,可进行太阳能资源的开发利用。     

青藏高原晴天太阳直接辐射的计算和分析

本文根据1979年5～8月青藏高原气象科学实验资料,研究了利用卡斯特洛夫公式计算青藏高原晴天太阳直接辐射的有关问题。首先从原始资料中挑选出晴天太阳直接辐射并计算其日平均辐照度,然后以此为标准,利用迭代法反求可能太阳直接辐射日平均辐照度理论公式中的系数C,建立该系数与平均水汽压的经验公式,再利用经验式反演晴天太阳直接辐射。本文还比较了由乌克兰英采夫法确定的可能太阳直接辐射与实际晴天太阳直接辐射的差异,证实前者要比后者偏大,其偏离程度随站点拔海高度增加而缩小。文中最后讨论了青藏高原晴天太阳直接辐射日平均辐照度的地理分布,并分析了其随拔海高度的变化。     

自然环境条件对太阳能资源计算影响的再思考

文章简单回顾了以前国内常用的太阳辐射资源的计算方法,评论了各自存在的主要问题。其中最重要的是我国大地势以及其他自然条件影响下的基础辐射问题。在以前的研究中虽也注意到了这一问题,但解决得既不理想,也不彻底。关键是这些解决方法依靠的仅仅是辐射实测站点的天文辐射数据。由于测站有限,直接影响到对不同经度、纬度、地势、气候等自然条件下的基础数据的推算。该文利用SMARTS模式依据每个气象站的平均气压、绝对湿度、能见度等数据推算出符合当地环境条件的晴天辐射数据,作为基础辐射数据,进而达到考虑各地真实大气条件来计算晴天辐射的目的。     

Prevailing cloud types in Athens

Summary Prevailing cloud types and their daily, annual and interannual variation in the region of Athens were examined. These cloud types were grouped into five major classes: cumuliform, stratiform, cirriform, medium altitude clouds and no cloud class, referred to in the study as clear skies. The results are expressed as frequency of occurrence of different cloud classes.It is found that clear skies and prevailing cumuliform clouds both have summer maxima. Stratiform and medium altitude clouds have winter maxima, while cirriform clouds exhibit a semiannual variation, with maxima in May and October.In terms of interannual trends, the tendency of stratiform clouds to prevail decreases while the tendency of cumuliform clouds to prevail increases, probably due to urban expansion and the increase in urban activity.With 10 Figures     

地球大气纬向风系、副热带高压和太阳较差自转的形成机制

利用N S(Navier Stokes)方程和一个基本假设推导出星体大气平均纬向风和平均气压公式,根据公式讨论了地球大气纬向风系和平均气压以及副热带高压的成因并进行了数值模拟。结果发现,地球大气纬向风是大气微团密度与基准大气密度存在差异而形成的,大气微团的密度大于（小于）基准密度,则为西风（东风）;密度的差距越大,风速越强。在中高纬度地区大气微团吸收的太阳辐射少而向空间辐射多,导致其密度变大,因此在中高纬度盛行西风;而在低纬度地区,因为吸收的太阳辐射多使大气微团密度变小而盛行东风。夏季（冬季）太阳辐射增强（减弱）使得大气微团密度变小（增大）,进而导致中高纬度地区西风减弱（增强）和低纬度地区的东风加强（减弱）。风速的大小还与纬度的余弦成正比,这就使得最大西风带位于中纬度地区而不是大气微团密度最大的极地附近;也使得最大的东风不是发生在太阳直射点附近而是靠近赤道一侧。根据气压公式和大气密度的经向差异可以得出中高纬度区域气压随纬度的升高而减小的分布特征,而太阳辐射所造成低纬地区密度的减小是该区域气压大于中高纬度的主要原因;在赤道上纬度的正弦为零,使得气压在赤道上存在极小值,导致了赤道槽和副热带高压的形成,且太阳辐射越强、副热带高压越强。因为纬度正弦因子的存在,使得副高脊线总是位于太阳直射点的向极一侧。在假定太阳大气为理想气体的情况下,由N S方程推导出太阳大气自转角速度随纬度的变化公式,由此解释了太阳较差自转的成因在于低纬地区的大气微团密度大于高纬度,并且在赤道上大气微团的密度最大。该公式与观测得到的经验公式在略去高阶小项后一致。由此认为,太阳大气的运动在形成机制上与地球大气没有区别,不同的是在太阳表面没有象地球表面那样受太阳辐射的影响,N S方程是所有星体（包括恒星、行星）大气共同遵守的动力方程。     

濮阳市0 cm地温变化特征及成因分析

利用线性分析方法和相关分析方法,分析了濮阳近50年地面温度的变化倾向率及成因。月平均地面温度变化趋势具有明显的阶段性,12月至翌年4月呈升温趋势,5～11月呈降温趋势,其变化倾向率分别为0．01～0．32℃／10a和-0．04～-0．83℃／10a,年平均地面温度变化倾向率为-0．23℃／10a;各月地面平均最高温度的变化倾向率,11月为0．01℃／10a,其余月份则为-0．46～-2．16℃／10a,年变化倾向率为～0．23℃／10a;各月地面平均最低温度的变化倾向率,11月为-0．02℃／10a,其余月份则为0．09～0．76℃／10a,年变化倾向率为0．34℃／10a;各月平均地气温差的变化倾向率为-0．17～-0．66℃／10a,年变化倾向率为-0．35℃／10a。当地地面平均最高温度呈逐年递减趋势,地面平均最低温度呈逐年递增趋势,地面平均最高温度的递减趋势远大于平均最低温度的递增趋势,因此,年平均地面温度呈逐年递减趋势。地气温差逐年递减,大气稳定度增强,不利于近地层污染物和水汽扩散,由此带来轻雾日数增多,空气污染加重。日照时数减少,地面受太阳直接辐射减少,是地面温度趋降的直接原因,空气湿度和降水量趋增、空气污染加重等要素的变化,是地面温度趋降的间接原因。     

晴天地表总辐射和净辐射瞬时值计算方法

以较为精确的大气辐射传输模式为基础,研制出晴天地表总辐射和净辐射瞬时值的计算方案。与以往的经验计算方法不同,该方案将辐射传输带模式的思路引入地面太阳辐射计算,并尽可能将大气中吸收和散射物质对太阳辐射的影响考虑进去,从而使该方法具有较好的精确性和普适性。在此基础上采用了Kokhanovsky等人提出的大气气溶胶反射率和透过率参数化方案,使得气溶胶对地面总辐射和净辐射的影响得到较好的处理。采用的自变量都是数值预报模式或卫星观测能提供的气象要素,因此该方案即可用于数值预报模式或陆面过程模式计算地表辐射平衡,又可以利用卫星观测或再分析资料估算地面太阳能资源分布。利用美国能源部三个大气辐射观测站点2005年全年的观测资料及欧洲宇航局提供的卫星反演气溶胶资料对计算方案进行了检验。结果表明,该方法十分精确,所有点的平均相对误差都小于6%,误差的均方差都小于0.3 W•m^-2。     

Assessment of FY-4A and Himawari-8 Cloud Top Height Retrievalthrough Comparison with Ground-Based MillimeterRadar at Sites in Tibet and Beijing

正1Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics,Chinese Academy of Sciences, Beijing 100029, China2University of Chinese Academy of Sciences, Beijing 100049, China     

广西地面太阳辐射分布特征以及对人体健康的影响

选用2001-2010年广西桂林、南宁、北海3个地面太阳辐射站的总辐射资料及日照时数资料,分析了总辐射日总量、日最大值的年变化规律,时总量的日变化规律,日最大值出现时间频率的分布区间等,结果表明：（1）广西太阳总辐射的日总量、日最大值强度的年变化规律明显。总体呈现夏季最大,春秋季次之,冬季最小的特点。大多数情况下,随着纬度由北向南递减,总辐射值递增。日总量与日照时数的年变化趋势存在正向的线性相关。（2）广西太阳总辐射的时总量的日变化规律明显。总体呈现中午前后强．早晚弱的特点。最大值一般出现在一天中的10-14时这个区间．     

安徽省淮南森林冠层辐射传输过程的特征

本文利用淮南森林观测站2018年7月1日至2019年6月30日冠层辐射观测,分析了淮南栎树森林下垫面冠层内外辐射变化特征。结果表明:（1）从春季到夏季,栎树冠层之上向下的太阳短波辐射增加,到冬季逐渐减少。从早春开始,由于叶片生长增多,冠层中间和冠层之下向下的太阳短波辐射下降,从秋季到冬季树叶凋落,其向下的太阳辐射增加,与冠层之上的变化趋势相反;对于向上的短波辐射,无论冠层之上、冠层中间还是冠层之下,随季节的变化都与向下的短波辐射相似,只是数值小很多。（2）冠层之上、冠层中间和冠层之下向下的长波辐射,随时间的变化从春季逐渐开始增大至夏季达到最大,随后逐渐减小并在冬季达到最小;就空间变化而言,冠层中间和冠层之下向下的长波辐射值比冠层之上的辐射值高,使得冠层对长波辐射的振幅增大,晴空条件最高可达1.3倍。（3）淮南森林区冠层之上（距地面25 m）年平均反照率为0.14,比中国北方地区（35°N）温带季风气候区（混交林为主）反照率的整体水平低0.01,表明淮南的森林茂密、灌丛更多些。（4）冠层上部分和整层的短波辐射透射率主要受叶片的影响。夏季,冠层的短波透射率平均为0.1。到了冬天,叶子凋落,透射率增加并趋于一个平稳的波动。冠层的短波辐射吸收率在夏季最高,秋季逐渐降低,随着叶子凋落在冬季迅速减小,趋于一常值。     

临安与龙凤山辐射数据质量及初步结果比较

采用国际通用的辐射数据质量评估方法对2005—2011年浙江临安、黑龙江龙凤山两个区域大气本底站辐射观测资料进行质量评估与比较分析。结果表明:两站辐射数据通过物理可能限制检验与极端罕见限制检验的百分比均超过99.5%,但通过相关要素比较限制检验的百分比上,临安与龙凤山站分别降至97.9%与95.9%;双轴定位追踪太阳出现偏差是造成直接辐射与散射辐射数据精度降低的主要原因。CM21表的热偏移在-5 W·m-2以内,而其进行热偏移订正可以显著提高数据的通过率。对应同一太阳天顶角,临安站晴空总辐射与直接辐射均低于龙凤山站,散射辐射则相反,其原因是临安的大气透明系数较低,大气浑浊度较高。2006—2011年,临安站的大气向下长波辐射呈下降趋势,达到了0.01的显著性水平,且其多年平均值 (363.7±59.3 W·m-2) 显著高于龙凤山站 (274.9±77.6 W·m-2);龙凤山站晴空太阳总辐射呈增加趋势,达到了0.1的显著性水平。     

2011年地面入射太阳辐射变化及其与敏感因子回归分析

太阳辐射是地球上一切生命的源泉,亦是地球天气、气候系统发生发展和演变的能量来源。利用FY2E卫星遥感产品地面入射太阳辐射资料和地面常规观测资料,对2011年鹤壁市地面入射太阳辐射变化特征分析结果表明：鹤壁市2011年地面入射太阳辐射日曝辐量和月累积量的变化有明显的季节性,其年累积量为5721．38MJ·m^-2,日曝辐量3—4月增加迅速,其中3月份环比增长59％。地面入射太阳辐射总体变化趋势可以用一元多项式进行回归拟合,拟合曲线与实测资料的相关系数达0．8。地面最高温度与地面入射太阳辐射存在明显正相关,地面入射太阳辐射增大,地面最高温度就会升高。地面蒸发量对地面入射太阳辐射高度敏感,地面入射太阳辐射增大,地面蒸发量就会增大。通过对地面入射太阳辐射与地面敏感气象要素的多元回归分析发现,地面入射太阳辐射的二元线性回归预测水平高于一元线性回归预测水平。通过地面气象要素的多元线性回归预测,可估算地面入射太阳辐射值,这为相关研究及业务服务等提供了一种获取地面入射太阳辐射的方法。     

IAP AGCM中短波辐射方案的改进研究I·引入Fu-Liou短波辐射方案

冰云和水云对短波辐射性质(消光系数、单次散射反照率及不对称因子)的影响很不相同,应分别计算。Fu-Liou短波辐射方案(以下称Fu-Liou code)就是对冰云和水云分别采用了不同的参数化方案,云的短波辐射性质直接由云的物理性质来确定。因此,Fu-Liou code在云的处理方面物理意义更清晰且很合理。作者将Fu-Liou code引入IAP AGCM-II中,称为Version 2。对当代气候场的模拟结果表明,Version 2的各个物理过程是协调匹配的,且其对气候场的模拟性能是好的,从而为进一步改进IAP AGCM的短波辐射方案提供了很好的模式基础。     

Seasonal Characteristics of Surface Radiation Fluxes on the East Rongbuk Glacier in the Mt. Everest Region

Ground-based measurements are essential for understanding alpine glacier dynamics, especially in remote regions where in-situ measurements are extremely limited. From 1 May to 22 July 2005 (the spring-summer period), and from 2 October 2007 to 20 January 2008 (the autumn-winter period), surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l. by using an automatic weather station (AWS). The results show that surface meteorological and radiative characteristics were controlled by two major synoptic circulation regimes: the southwesterly Indian monsoon regime in summer and the westerlies in winter. At the AWS site on the East Rongbuk Glacier, north or northwest winds prevailed with high wind speed (up to 35 m s-1 in January) in winter while south or southeast winds predominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer. Intensity of incoming shortwave radiation was extremely high due to the high elevation, multiple reflections between the snow/ice surface and clouds, and the high reflective surrounding surface. These factors also caused the observed 10-min mean solar radiation fluxes around local noon to be frequently higher than the solar constant from May to July 2005. The mean surface albedo ranged from 0.72 during the spring-summer period to 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was greatly affected by the cloud condition and atmospheric moisture content. The overall impact of clouds on the net all-wave radiation balance was negative in the Mt. Qomolangma region. The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except for a few overcast days. On monthly basis, the net all-wave radiation was always positive.     

Aerosol modulation of atmospheric and surface solar heating over the tropical Indian Ocean

The major finding of this study is that aerosols over the tropical Indian Ocean enhance clear sky atmospheric solar heating significantly and decrease the surface solar heating by even a larger amount. The results presented here are based on aerosol chemical, microphysical, and optical and radiometric data collected at the island of Kaashidhoo (4.97°N, 73.47°E) during February and March of 1998, as part of the first field phase of the Indian Ocean experiment (INDOEX). The aerosol optical properties were integrated with a multiple scattering Monte Carlo radiative transfer model which was validated at the surface with broadband flux measurements and at the top of the atmosphere (TOA) with the clouds and earth's radiant energy system (CERES) radiation budget measurements. We consider both externally and internally mixed aerosol models with very little difference between the two models in the estimated forcing. For the February–March period, the aerosols increase the monthly mean clear sky atmospheric solar heating by about 12 W/m²(about 15% of the total atmospheric solar heating) and decrease the sea surface clear sky solar heating by about 16 W/m² with a daily range from 5 to 23 W/m². The net aerosol forcing at the top of the atmosphere is about −4 W/m² with a daily range from −2 to −6 W/m². Although the soot contributes only about 10% to the aerosol optical thickness, it contributes more than 50% to the aerosol induced atmospheric solar heating. The fundamental conclusion of this study is that anthropogenic aerosols over the tropical Indian Ocean are altering the clear sky radiation budget of the atmosphere and surface in a major manner.