Study of Distinctive Regional Features of Surface Solar Radiation in North and East China

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance.Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment,including the climate change.To provide useful information for predicting the future climate change in China,distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007.Multiple models,such as the plane-parallel radiative transfer model,empirical and statistical models,and corrclation and regrcssion analysis methods are used in the study.The results are given as follows.(1) During 1961-2007,the total SSR in North China went through a process from quickly “dimming” to slowly “dimming”,while in East China,a significant transition from “dimming” to “brightening” occurred.Although there are some differences between thc two regional variation trends,long-term variations in SSR in the two regions are basically consistent with the observation worldwide.(2) Between the 1960s and 1980s,in both North and East China,aerosols played a critical rolc in the radiation dimming.However,after 1989,different variation trends of SSR occurred in North and East China,indicating that aerosols were not the dominant factor.(3) Cloud cover contributed less to the variation of SSR in North China,but was thc major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening,especially in the “remarkable brightening” period,with its contribution as high as 70％.     

Relative contributions of sublimation and volcanoes to Io's atmosphere inferred from its plasma interaction during solar eclipse

We present a model that describes Io's delayed electrodynamic response to a temporal change in Io's atmosphere. Our model incorporates the relevant physical processes involved in Io's atmosphere-ionosphere-magnetosphere electrodynamic interaction to predict the far-ultraviolet (FUV) radiation as Io enters Jupiter's shadow and re-emerges into sunlight. The predicted FUV brightnesses are highly nonlinear as the strength of the electrodynamic interaction depends on the ratios of ionospheric conductances to the torus Alfvén conductance, but the former are functions of electrodynamics and the atmospheric density, which decays rapidly upon entering eclipse. Key factors governing the time evolution are the column density due to sublimation and the column density due to volcanoes, which maintain the background atmosphere during eclipse. The plasma interaction does not react instantaneously, but lags to a temporarily changing atmosphere. We find three qualitatively different scenarios with two of them including a post-eclipse brightening. The brightness ratio of in-sunlight/in-eclipse coupled with the existence of a sub-jovian equatorial spot constrains the volcanic column density to several times 10¹⁸ m⁻², based on the currently available observations. Thus in sunlight, the sublimation driven part of Io's atmosphere dominates the volcanically driven contribution by roughly a factor of 10 or more.     

Influence of Changes in Solar Radiation on Changes of Surface Temperature in China

The long-term trends of total surface solar radiation(SSR),surface diffuse radiation,and surface air temperature were analyzed in this study based on updated 48-yr data from 55 observational stations in China,and then the correlation between SSR and the diurnal temperature range(DTR) was studied.The effect of total solar radiation on surface air temperature in China was investigated on the basis of the above analyses.A strong correlation between SSR and DTR was found for the period 1961-2008 in China.The highest correlation and steepest regression line slope occurred in winter,indicating that the solar radiation effect on DTR was the largest in this season.Clouds and water vapor have strong influences on both SSR and DTR,and hence on their relationship.The largest correlations between SSR and DTR occurred in wintertime in northern China,regardless of all-day(including clear days and cloudy days) or clear-day cases.Our results also showed that radiation arriving at the surface in China decreased significantly during 1961-1989(dimming period),but began to increase during 1990-2008(brightening period),in agreement with previous global studies.The reduction of total SSR offset partially the greenhouse warming during 1961-1989.However,with the increase of SSR after 1990,this offsetting effect vanished;on the contrary,it even made a contribution to the accelerated warming.Nonetheless,the greenhouse warming still played a controlling role because of the increasing of minimum and mean surface temperatures in the whole study period of 1961-2008.We estimated that the greenhouse gases alone may have caused surface temperatures to rise by 0.31-0.46℃(10 yr) 1 during 1961-2008,which is higher than previously estimated.Analysis of the corresponding changes in total solar radiation,diffuse radiation,and total cloud cover indicated that the dimming and brightening phenomena in China were likely attributable to increases in absorptive and scattering aerosols in the atmosphere,respectively.     

1961～2009年我国地面太阳辐射变化特征及云对其影响的研究

基于我国100个地面站点的地面太阳总辐射、日平均云量资料分析1961～2009年我国地面太阳辐射(Surface Solar Radiation,SSR)变化特征及云在不同时期对SSR的影响。结果显示:1961～2009年我国SSR经历了先下降后上升的变化过程,其中1961～1990年SSR显著下降("变暗"),下降速率为-4.3%/10 a(7.87 W m–2(10 a)–1),各地SSR变化趋势比较一致;1990年后SSR开始上升("变亮"),上升速率为2.8%/10 a(2.4 W m–2(10 a)–1),各地SSR变化趋势不如前一阶段一致,但没有显著的地域分布特征。晴空条件的设置对1961～1990年各站点SSR变化特征影响不大,仍为大范围下降("变暗"),但对1990～2009年的结果影响显著。相比全天空条件的结果,晴空条件下1990～2009年我国SSR变化有明显的南北特征,南方地区以"变亮"为主,而北方地区大多继续"变暗",但"变暗"速度减缓。1961～1990年我国总云量总体呈小幅下降趋势,下降速率很慢,这一时期总云量与全天空SSR没有很好的对应关系;1990～2009年我国总云量总体呈小幅上升趋势,有显著的南北分布差异,北方地区以上升趋势为主,南方地区以下降趋势为主,期间云量与全天空情况下SSR有很好的对应关系。这些结果表明,在"变暗"阶段,云对SSR的作用不显著,而在"变亮"阶段,云的作用变得较为突出。     

Study of distinctive regional features of surface solar radiation in North and East China

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance. Variations in solar radiation incident at the earth’s surface profoundly affect the human and terrestrial environment, including the climate change. To provide useful information for predicting the future climate change in China, distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aer...     

全球“变暗”和“变亮”时期中国地面温度变化研究

利用中国90个气象站年平均地面日最高、日最低温度和地面太阳辐射数据,分析了在全球变暖背景下全球“变暗”和“变亮”时期中国地面温度的变化特征及其与到达地面的太阳辐射(SSR)变化之间的联系.结果表明,在全球“变暗”时期,年平均地面日最高和日最低温度的差别较大,日最高温度先下降后缓慢上升,日最低温度先平缓变化后快速上升,日最低温度的上升速率始终大于日最高温度,且两者变化速率之差＞0.3℃·(10 a)-1.从空间分布上看,年平均日最高和日最低温度都表现出明显的南北差异,中高纬度地区(35°N以北)增温(或保温)的趋势更强,这与该地区SSR下降幅度相对较小一致.在全球“变亮”时期,年平均地面日最低温度继续上升,相对于“变暗”时期升温速率变化不大;而年平均日最高温度上升速度明显加快,此时年平均日最高和日最低温度的升温速率趋于一致.年平均日最高温度仍有明显的地域差异,中低纬度(35°N以南)地区的升温速率大于中高纬度,这与中低纬度SSR上升而中高纬度SSR下降有较好的对应关系;年平均日最低温度没有表现出这种南北差异,与SSR变化也没有很好的对应关系.尽管20世纪90年代后SSR开始上升,但目前SSR仍未恢复到“变暗”初期(60年代)的水平,而当前地面日最高和日最低温度已远高于“变暗”初期.     

1961～2007年西北地区地面太阳辐射长期变化特征研究

利用西北地区16个甲级辐射站1961～2007年的总辐射资料,和1961～1992年的直接辐射、散射辐射资料,研究该地区地面太阳辐射的长期变化特征。发现,从1961～2007年总辐射的长期变化经历了"维持"、"变暗"、"变亮"和"回落"4个阶段。其中从70年代至80年代中期总辐射持续"变暗",之后开始转折"变亮"。"变亮"过程持续到90年代中期基本停止,之后振荡"回落"。各个季节总辐射的长期变化都表现出"变暗"和"变亮"这两个明显特征,其中冬季的"变暗"过程持续时间最长,"变亮"过程持续时间最短。从1961～1992年,直接辐射的变化过程为先下降后回升,散射辐射则是先上升后下降,两者的变化趋势和相对幅度决定了总辐射在不同阶段的变化趋势。60年代至80年代中期是西北地区直接辐射下降的主要时期,直接辐射和日照时数的下降过程具有地域性和季节性差异,表现为省会城市和冬季的下降百分率最显著。这种特征表明气溶胶排放的增加或许是影响该地区直接辐射和日照时数减小的因子之一。     

The formation of radio brightening bands near cool filaments on the Sun

We analyze the spatial distribution of the intensity of radio emission from a cool filament in terms of the generalized Kippenhahn-Schluter model. Based on a numerical calculation of the centimeter radio emission and using the temperature transition layer model by Anzer and Heinzel (1999), we show that two symmetric brightening bands must be observed near the filament. The absence of any bands during observations with a sufficient angular resolution suggests that a different type of model is realized: a model with a narrow (unobservable) temperature transition layer across a magnetic field, in particular, a Kuperus-Raadu-type model.