Mismatch between variations of solar indices, stratospheric ozone and UV-B observed at ground

In solar cycles 22–23, all solar indices showed maxima near 1990 and 2000 and minima in 1996. The maximum to minimum variation was only 1–2% in the UV range 240–350 nm. Dobson ozone intensities did not show any clear relationship with solar cycle and ozone variations were less than 10%. The UV-B (295–325 nm) observed at ground by Brewer spectrophotometers at some locations had variations of 50–100% for 295–300 nm, and 20–50% for 305–325 nm. The maxima were in different years at different locations (even with separations of only 300 km), did not match with the solar cycle, and were far too large to be explained on the basis of ozone changes (1% decrease of ozone is expected to cause 2% increase of UV-B). Thus, if the data are not bad, the UV-B changes do not match with solar activity or ozone changes and must be mostly due to other local effects (clouds, etc.?). When data are averaged over wide geographical regions, UV-B variation ranges are smaller (10–20%, probably because localised, highly varying cloud effects get filtered out), and are roughly as expected from ozone variations.     

Stratospheric ozone response to a solar proton event: Hemispheric asymmetries

Ozone depression in the polar stratosphere during the energetic solar proton event on 4 August 1972 was observed by the backscattered ultraviolet (BUV) experiment on the Nimbus 4 satellite. Distinct asymmetries in the columnar ozone content, the amount of ozone depressions and their temporal variations above 4 mb level (38 km) were observed between the two hemispheres. The ozone destroying solar particles precipitate rather symmetrically into the two polar atmospheres due to the geomagnetic dipole field These asymmetries can be therefore ascribed to the differences mainly in dynamics and partly in the solar illumination and the vertical temperature structure between the summer and the winter polar atmospheres. The polar stratosphere is less disturbed and warmer in the summer hemisphere than the winter hemisphere since the propagation of planetary wave from the troposphere is inhibited by the wind system in the upper troposphere, and the air is heated by the prolonged solar insolation. Correspondingly, the temporal variations of stratospheric ozone depletion and its recovery appear to be smooth functions of time in the (northern) summer hemisphere and the undisturbed ozone amount is slighily, less than that of its counterpart. On the other hand, the tempotal variation of the upper stratospheric ozone in the winter polar atmosphere (southern hemisphere) indicates large amplitudes and irregularities due to the disturbances produced by upward propagating waves which prevail in the polar winter atmosphere. These characteristic differences between the two polar atmospheres are also evident in the vertical distributions of temperature and wind observed by balloons and rocker soundings.     

Solar response in the temperature over the equatorial middle atmosphere

One of the longest temperature records available for the equatorial region is provided by Rocketsonde from Thumba (8°N, 77°E), India during the period 1971–1993. In recent times, these data sets are reanalyzed using the up-to-date regression models, which take care of several corrections and parameters, not accounted for in earlier analyses and hence affecting the conclusions. In this paper, annual mean solar response in this data set along with the seasonal solar coefficient is quantitatively estimated now with improved confidence. A negative solar response in the stratosphere (1–2 K/100 solar flux unit, sfu) and a positive response for the mesosphere (0.5–3 K/100 sfu) are found. The negative stratospheric solar response is in contrast to the solar coefficient reported for low latitudes by earlier workers for other stations.     

Relationship of atmospheric ozone profiles to solar magnetic activity

The observed relationship between atmospheric vorticity variations and solar magnetic sector boundary passages is examined for a possible connection via ionization changes affecting ozone distributions. A superposed epoch analysis was performed on Umkehr distributions for 18 years from Arosa, Switzerland, with use of more than 500 solar sector boundary passages as keyday zero. No significant responses are observed in any Umkehr level or in total observed ozone amounts. Further analyses on shorter records for Belsk, Poland, and Hohenpeissenberg, West Germany, corroborate these results. Another analysis for Arosa with about 100 type IV solar flares as keyday zero also shows no definitive trend. It is concluded that ozone distribution changes cannot be the primary causative mechanism for vorticity variations.Journal Paper No. J-8838 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1852.     

基于太阳辐照校准地基日冕仪光度的方法研究及初步测试

利用地基日冕仪对更靠近太阳临边的日冕进行成像观测,对于深入研究日冕结构的产生及演化等非常重要.为得到准确的观测数据,本论文提出了地基日冕仪光度校准和补偿方法.针对观测谱线为530.3 nm的地基日冕仪原理样机,我们搭建了实验室测试系统校准日冕仪.同时,为对大气传输路径上的光损失进行补偿,我们研制了太阳辐照计,用于同步记录太阳光球辐照度作为参考基准.在威海进行了实地观测,实验表明：采用不同光电探测器的两套辐照计地面测试结果的相对偏差不超过0.5%,由此估计地基日冕仪光度校准总的相对不确定度约为0.54%,验证了该方法是精确和可行的.据此确立的数据处理流程将用于子午工程二期建设设备中光谱成像日冕仪的科学数据产出,并可为空间日冕仪光度校准提供可能的解决方案.

     

Uncertainties of the relationship between the equatorial quasi-biennial oscillation, the Arctic stratosphere and solar forcing

Two different equatorial quasi-biennial oscillation (QBO) indices, two reanalyses and radiosonde observations are used to analyze the Arctic stratospheric temperature and height. This analysis was used to assess the uncertainties in the connection of solar forcing, QBO and the Arctic variability. The results show that (1) the frequency of the westerly/easterly phases of the QBO over the stratospheric equator has a significant multiple peak seasonal variation. The primary seasonal peaks occur in February, March and April for the westerly phase of the QBO and the easterly phase peaks in June, July and August. (2) The correlation of stratospheric Arctic temperature and height with the solar radio flux shows statistical significance in February or July/August even if there is no stratified phase of QBO (easterly and westerly phases) involved. However, when the correlation was computed according to the stratified phase of QBO, the solar signals in both temperature and height fields are remarkably amplified in February and November under the westerly phase, but the signal in the height field is most significant only in August under the easterly phase. (3) The impact of the QBO and solar forcing on the stratospheric temperature and heights in the Arctic varies depending on the season. The impacts are also sensitive to the specific height of the QBO-defined level that is used, the specific period of the analysis and the dataset used.     

西藏羊八井地区太阳短波辐照度特征及其短期预测模型对比分析

本研究利用西藏羊八井太阳短波辐照度观测数据分析了该地区2020—2021年的辐射时间序列分布特征,基于时间序列分析、随机森林（Random Forest,RF）和Prophet进行建模预测,通过对比研究探究三种模型在该地区的适用性以及提高模型预测精度的方法.结果表明：该地区短波太阳辐照度呈双峰倒U型分布的月变化和单峰倒U型分布的日变化特征.RF在选用模型中最优,其标准化均方根误差（Normalized Root Mean Square Error,NRMSE）、决定系数R2分别为17.54%和0.962.小波变换去噪能提高各模型预测精度,NRMSE降低4.82%~12.94%.组合模型能提高预测精度,误差倒数权重组合模型的NRMSE较差分自回归滑动平均模型（Autoregressive Integrated Moving Average,ARIMA）和Prophet分别下降35.22%、25.12%.预测时间步长差异也会影响预测效果,模型的预测误差随时间步长逐渐增大而减小.因此,可利用RF等机器学习模型在西藏地区进行太阳辐照度短期预测,通过小波变换、组合模型、预测时间步长等环节提高预测精度,以满足当地光伏发电对太阳辐照度的预测需求.     

Temperature variability in central Mexico and its possible association to solar activity

Minimum extreme temperature variability from five meteorological stations in the central part of Mexico covering a period from 1920 to 1990 is examined. We found a correlation coefficient (r=0.65) between these temperature records and geomagnetic activity. Furthermore, by performing spectral analysis peaks were obtained with similar periodicities to those found in the sunspot number, the magnetic solar cycle, cosmic ray fluxes and geomagnetic activity; all of these phenomena are modulated by solar activity. Signals with periodicities comparable to those observed in El Niño and the Quasi-Biennial Oscillation were also identified. We conclude that the solar signal is probably present in the minimum extreme temperature record of the central part of Mexico.     

Latitudinal and longitudinal variability of mesospheric winds and temperatures during stratospheric warming events

Continuous MF and meteor radar observations allow detailed studies of winds in the mesosphere and lower thermosphere (MLT) as well as temperatures around the mesopause. This height region is characterized by a strong variability in winter due to enhanced planetary wave activity and related stratospheric warming events, which are distinct coupling processes between lower, middle and upper atmosphere. Here the variability of mesospheric winds and temperatures is discussed in relation with major and minor stratospheric warmings as observed during winter 2005/06 in comparison with results during winter 1998/99.Our studies are based on MF radar wind measurements at Andenes (69°N, 16°E), Poker Flat (65°N, 147°W) and Juliusruh (55°N, 13°E) as well as on meteor radar observations of winds and temperatures at Resolute Bay (75°N, 95°W), Andenes (69°N, 16°E) and Kühlungsborn (54°N, 12°E). Additionally, energy dissipation rates have been estimated from spectral width measurements using a 3 MHz Doppler radar near Andenes. Particular attention is directed to the changes of winds, turbulence and the gravity wave activity in the mesosphere in relation to the planetary wave activity in the stratosphere.Observations indicate an enhancement of planetary wave 1 activity in the mesosphere at high latitudes during major stratospheric warmings. Daily mean temperatures derived from meteor decay times indicate that strong warming events are connected with a cooling of the 90 km region by about 10–20 K. The onset of these cooling processes and the reversals of the mesospheric circulation to easterly winds occur some days before the changes of the zonal circulation in the stratosphere start indicating a downward propagation of the circulation disturbances from the MLT region to the stratosphere and troposphere during the stratospheric warming events. The short-term reversal of the mesospheric winds is followed by a period of strong westerly winds connected with enhanced turbulence rates and an increase of gravity wave activity in the altitude range 70–85 km.     

AIRS卫星温度和臭氧廓线在南极的验证分析

利用2008年中山站、Amundesen-Scott（SouthPole）站和Neumayer站为期一年的温度和臭氧探空数据,对AIRS第六版温度和臭氧垂直廓线产品在南极的精度进行了验证.结果表明,AIRS温度与探空温度总体上具有显著的一致性,其中对流层偏差最小（RMSe < 2℃）,近地面温度由于受到下垫面影响偏差略大（RMSe~2℃）,平流层偏差较大（2℃ < RMSe < 3℃）,AIRS温度平均低于探空观测且受季节变化影响显著,秋冬季偏差整体上高于春夏季.AIRS臭氧反演精度在平流层（RMSe~25%）要优于对流层（RMSe~30%）,RMSe最大值出现在UT-LS区域（可达40%）且在"臭氧洞"期间明显增大.AIRS产品精度在南极沿岸和内陆存在差异,由于南极地区探空资料较少且主要位于沿海,故在南极内陆地区进行探空观测对于提高卫星资料精度,改善该区域天气预报能力具有重大意义.     

太阳绕太阳系质心运动22年周期及其与太阳活动的联系

对于太阳活动22年周期的成因机制长期存在着争论.本文借助于行星会合指数以及开普勒第三定律,对太阳绕太阳系质心运动周期进行了分析计算.结果发现,太阳绕太阳系质心运动存在22.1826年显著周期,这与太阳磁场变化的22.20年周期相吻合.并从太阳系角动量守恒的角度解释了两者之间的成因联系:在太阳绕太阳系质心运动的准22年周期中,太阳系质心与太阳质心逐步接近而后逐步分离.当两个质心之间的距离接近零的时候,太阳轨道角动量与自转角动量叠加,会导致太阳自转角速度的加快;当两个质心之间的距离逐渐远离的时候,则导致太阳自转角速度的减慢.这可能是引发太阳活动和太阳磁场变化的原因.这一新认识为太阳活动准22年周期成因机制的解释提供了新的线索和依据.     

青藏高原对流层臭氧含量变化的太阳周期活动信号分析

利用1979~1992年卫星TOR对流层臭氧数据库资料,以及同期太阳辐照度数据序列,考察青藏高原对流层臭氧含量变化与太阳辐射周期变化之间的关系.分析表明,青藏高原对流层臭氧分布表现出与太阳辐照度相同的变化趋势,存在着明显的太阳周期变化特征.逐月线性回归分析表明,太阳辐照度增加导致青藏高原对流层臭氧增加的正效应.在太阳周期内,太阳辐射增加可使青藏高原对流层臭氧、平流层臭氧和臭氧总量分别增加1.31、4.97、6.628DU,或4.07%、2.04%、2.28%.该特征与赤道太平洋地区完全相反,分析产生差异的原因,至少应包括两方面因素：一是背景大气NOX和水汽含量的差异;二是青藏高原频繁发生的平流层-对流层大气物质交换和输送.     

Shallow groundwater temperature response to climate change and urbanization

Groundwater temperatures, especially in shallow (quaternary) aquifers respond to ground surface temperatures which in turn depend on climate and land use. Groundwater temperatures, therefore, are modified by climate change and urban development. In northern temperate climate regions seasonal temperature cycles penetrate the ground to depths on the order of 10–15 m. In this paper, we develop and apply analytic heat transfer relationships for 1-D unsteady effective diffusion of heat through an unsaturated zone into a flowing aquifer a short distance below the ground surface. We estimate how changes in land use (urban development) and climate change may affect shallow groundwater temperatures. We consider both long-term trends and seasonal cycles in surface temperature changes. Our analysis indicates that a fully urbanized downtown area at the latitude of Minneapolis/St. Paul is likely to have a groundwater temperature that is nearly 3 °C warmer than an undeveloped agricultural area at the same geographic location. Pavements are the main cause of this change. Data collected by the Minnesota Pollution Control Agency (MPCA) in the St. Cloud, MN area confirm that land use influences groundwater temperatures. Ground surface temperatures are also projected to rise in response to global warming. In the extreme case of a doubling of atmospheric carbon dioxide (2 × CO₂ climate scenario), groundwater temperatures in the Minneapolis/St. Paul metropolitan area could therefore rise by up to 4 °C. Compounding a land use change from “undeveloped” to “fully urbanized” and a 2 × CO₂ climate scenario, groundwater temperatures are projected to rise by about 5 °C at the latitude of Minneapolis/St. Paul.     

A note on the statistics of the largest geomagnetic storms per solar cycle

This note points out a problem with the way in which extreme value distributions have been fit to the intensities of the largest geomagnetic storms per solar cycle. An alternative method is described. This method is applied to observations of the three largest geomagnetic storms in solar cycles 11–22.     

On the solar/QBO effect on the interannual variability of total ozone and the stratospheric circulation over Northern Europe

Based on total ozone data from the World Ozone Data Center and stratospheric geopotential height data from the Meteorological Institute of Berlin Free University for the months of January through March for the time period of 1958–1996, the influence of the 11-year solar cycle and the equatorial quasi-biennial oscillation (QBO) on total ozone and the stratospheric circulation at 30 hPa over Northern Europe is investigated. The analysis is performed for different levels of solar activity. The relationship of the equatorial QBO with ozone and the stratospheric circulation over the study region exhibits unique features attributed to strong opposite connections between the equatorial zonal wind and ozone/stratospheric dynamics during periods of solar minimum and maximum. Using the Solar/QBO effect, a statistical extraction of the interannual variations of total ozone and stratospheric circulation over Northern Europe has been attempted. The variations extracted and observed for late winter show very good correspondence. The solar/QBO effect in total ozone and stratospheric dynamics over Northern Europe appears to be related to planetary wave activity.     

Sensitivity of the surface temperature to changes in total solar irradiance calculated with the WRF model

The temperature sensitivity of the WRF model to changes in Total Solar Irradiance (TSI). The simulations were performed for a region centered over the North Atlantic Ocean, including portions of Eastern North America, Western Europe and Northwest Africa. Four simulations were run with different TSI values. Also, a fifth simulation was performed in which we varied the initial atmospheric conditions, in order to compare the effect on the temperature of both, changes in the TSI and initial atmospheric conditions. Comparing temperature monthly averages we found that changes in TSI and in the initial conditions have a measurable impact on temperature in the region of study. The sensitivity of the model using non-dimensional parameters was also estimated. The numerical experiments show some features that might allow to distinguish between the effects on the temperature due to changes in TSI from those caused by initial conditions. However, TSI changes are of the same order of magnitude than those of disturbances in the initial conditions. We also found that the mean monthly values of temperature over the full grid, did not present significant variations due to changes of either initial conditions or TSI.     

平流层臭氧对人类活动排放氯化物及氮氧化物的非线性响应

利用本文所建立的平流层下部臭氧异相光化学系统,研究硫酸气溶胶表面积浓度以及氯化物和氮氧化物的排放强度对系统状态的影响.光化系统由19种分别来自氧族、氢族、氮族、氯族和碳族的化学成分组成.研究结果指出,仅就气溶胶而言,它不是一个重要的决定光化系统行为的因子.然而,当它与奇氯ClOx或奇氮NOx的外源共同影响系统时,通过复杂的非线性光化学过程,它将使系统的行为发生重大变化.可以看到,在某些确定的参数范围内,系统存在多平衡态解,并构成一个“折叠"突变流型.     

太阳磁场方向变化对于地球大气温度异常变化的意义

本文根据苏黎世天文台太阳黑子11年周期资料和太阳黑子磁场磁性变化周期特征,构建了太阳黑子磁场磁性指数MI(Magnetic Index)时间序列.分析表明：太阳活动磁性周期平均长度为22.2年,但是每个周期长度是不相等的;多数情况周期短时磁性指数较大,对应太阳活动水平强;周期变长时磁性指数较小,对应太阳活动水平较弱;太阳黑子磁场磁性指数序列也具有80～90年的世纪周期. 进一步研究指出,太阳黑子磁场磁性指数曲线由极小值升至极大值时期,太阳磁场南向,行星际磁场磁力线与地磁场磁力线重联,此时磁层为开磁层,太阳风将携带大量等离子体从向阳面进入地球磁层,从而使输入的动量、能量和物质大幅度增加,与北半球对流层增温时期对应;太阳黑子磁场磁性指数曲线由极大值下降至极小值时期,太阳磁场北向,与磁层顶地磁场同向,行星际磁场不会与地磁场发生重联,此时磁层为闭磁层,这种情况下,只有少数带电粒子能够穿越磁力线进入地球磁层,与北半球对流层降温时期对应.     

Sq等效电流在太阳活动周中的分析研究

Sq电流体系的产生与太阳密切相关,太阳的活动情况会对Sq电流体系造成直接的影响.本文应用1996年至2006年(第23太阳周)INTERMAGNET地磁台网以及中国地震局地球物理研究所国家地磁台网中心的全球地磁场观测数据,通过球谐分析的方法建模,对11年期间每月Sq内外源等效电流体系进行分离,分析Sq内外源等效电流在太阳活动周中的变化情况.结果表明,Sq内外源等效电流强度与太阳黑子的变化具有较高的相关性和一致性,内外源等效电流强度在太阳活动高年期间明显大于其在太阳活动的上升年和下降年期间的强度;Sq内外源等效电流焦点的纬度变化与太阳活动没有显著的一致性;Sq内外源等效电流强度的季节效应在太阳活动的高年和低年具有显著的差别,太阳活动高年期间等效电流强度在分点季节最大,而在其他年份南北半球的等效电流强度都是在各自半球的夏季达到最大.     

Solar irradiance and total ozone over El Arenosillo (Spain) during the solar eclipse of 3 October 2005

The ground track of the annular eclipse of 3 October 2005 crossed the Iberian Peninsula. The main objective of this work was to analyze the variability of the solar irradiance and the total ozone column during the course of this event at El Arenosillo (Southwestern Spain). For achieving this goal, two Kipp & Zonen broadband radiometers (one for measuring total solar irradiance and other for measuring ultraviolet erythemal solar irradiance), one NILU-UV multi-band instrument and one Brewer spectroradiometer were used in this work. Total irradiance (310–2800 nm), and ultraviolet erythemal radiation (UVER) were recorded at a high frequency of 5 s, showing a strong reduction (higher than 80%) of the irradiance at the maximum solar obscuration which was of 79.6%. The irradiance decrease during the course of the eclipse was positively correlated with the percentage of eclipse obscuration, showing a very high agreement (R²～0.99). The irradiance recorded at selected wavelengths from the NILU-UV instrument shows a more pronounced decrease in the UV irradiance at the lower wavelengths during the solar eclipse. Finally, the evolution of the total ozone column (TOC) derived from Brewer and NILU instruments during the eclipse presented an opposite behavior: while the Brewer derived TOC values increase about 15 DU, the NILU derived TOC values decrease about 11 DU. This opposite behavior is mainly related to an artifact in the spectral irradiances recorded by the two instruments.