基于WACCM+DART的临近空间SABER和MLS温度观测资料同化试验

基于WACCM+DART（Whole Atmosphere Community Climate Model，Data Assimilation Research Test-Bed）临近空间资料同化预报系统，以2016年2月的一次平流层爆发性增温（SSW）事件为例，开展了临近空间SABER（Sounding of the Atmosphere using Broadband Emission Radiometry）和MLS（Microwave Limb Sounder）温度观测资料集合滤波同化试验.结果表明:同化SABER和MLS温度观测资料可显著降低WACCM模式在中间层和平流层中上部（0.001～10hPa）大气温度场的预报误差，改善CR试验在SSW发生时中间层变冷现象偏强、纬向风场首次发生反转的层次偏低以及增温恢复阶段0.1～10hPa的东风层提前消退、纬向风速偏大、平流层顶位置偏高等现象.基于ERA5（The Fifth Generation of ECMWF Reanalyses）再分析资料的检验表明:同化SABER和MLS温度资料明显有利于减小北半球高纬度地区（60°-90°N）平流层中上层和下中间层（0.1～14hPa）纬向风场以及平流层和中间层中下层（0.01～100hPa）温度场的分析误差；同化低层大气观测也有利于减小0.1～14hPa纬向风场和0.01～100hPa温度场的分析误差，但是不如同化SABER和MLS温度资料对临近空间纬向风场和温度场分析误差的改善效果显著.      

卫星观测台风重力波数值模拟与直接对比验证

以ECMWF的T799资料作为WRF-ARW（V3.5）初始场,对卫星高光谱红外大气垂直探测器AIRS观测的2013年超强台风苏力激发平流层重力波过程进行数值模拟,并利用卫星观测对数值模拟结果进行了直接对比验证.数值模拟表明,该台风诱发的重力波在20~40km高度逆着东风背景流向东向上传播,在水平方向呈半圆弧状;大气的垂直扰动随着高度的增加而增强,在40km高度上达到0.5m·s-1.基于三维傅里叶变换的波谱分析表明,平流层重力波水平波长中心值在500km附近,周期为3~5h,垂直波长主要为10~26km.分析表明,在18~40km高度的净纬向动量通量为6.7×10-4~1.89×10-3Pa,背景流强迫计算值为-0.23~1.21m·s-1·d-1,且在18km和40km高度的数值较大.最后,基于辐射传输模式计算的直接对比表明,卫星观测与数值模拟同时揭示了激发的平流层波动可传至40km以上高度及距台风中心2000km以外的区域,且不同资料得到的波动形态、方位以及水平尺度具有较好的一致性.      

一次暴雨激发平流层重力波的卫星观测与数值模拟

针对卫星Aqua/AIRS观测到的与2011年7月25日山东省乳山市特大暴雨相伴的一次平流层重力波过程,利用中尺度数值模式WRF进行暴雨诱发平流层重力波的数值模拟.对模式输出的垂直速度场和温度扰动场的分析表明,暴雨在平流层内的弧状波结构主要集中在降水云系东侧,水平影响范围大于1000km,且随着高度的增加,圆弧状结构趋于闭合,波动能量显著增强.此外,对垂直速度剖面结构分析表明,受高空东风和风切变的影响,重力波在上传过程中逆着背景风场向东传输,不同高度波动形态各异.基于快速傅里叶变换（FFT）的功率谱分析结果表明,此次暴雨激发的平流层重力波在35km高度的周期为7~20h,水平波长约为1000km,垂直波长为5~10km.通过分析动量通量的垂直输送,定量反映出重力波上传过程中的动力学变化特征.      

中国上空平流层准零风层的特征分析

利用ECMWF提供的ERA-40再分析风场资料首次分析了中国上空平流层准零风层的特点及其随季节和地理位置的变化特征.结果表明,准零风层一般处于18～25 km高度范围内,零风线所在的高度随时间和地理位置的不同稍有变化.根据准零风层随纬度的变化特征,中国上空可以分成三个区域:低纬地区(5°N～20°N)、中低纬过渡区域(20°N～32.5°N)和中高纬地区(32.5°N～55°N).低纬地区一般在冬季和初春有准零风层结构存在;中高纬地区一般在春末和夏季存在准零风层结构;而中低纬过渡区域是否有准零风层结构存在还与准两年震荡(QBO)有关,在QBO东风相位时,过渡区域呈现的特性偏向于中纬特性,在QBO西风相位时,过渡区域呈现的特性偏向于低纬特性.准零风层随经度变化非常小,零风线所在高度随经度的变化幅度一般不超过2 km,过渡区域的变化幅度相对大些.      

对流层顶变化对上对流层/下平流层臭氧分布的影响

上对流层和下平流层(UT／LS)，位于8-25km高度之间，是大气中一个很特殊的区域．大部分的臭氧分布在下平流层，在下平流层臭氧的含量发生一个很小的变化，就会对气候和地面的紫外辐射产生很大的影响．而作为气象参数的对流层顶，是充分混合、缺乏臭氧的上对流层和层结稳定、臭氧丰富的下平流层之间的边界或过渡层，其变化对臭氧总量和分布有直接和明显的影响．本文使用二维模式模拟研究对流层顶变化对臭氧在UT／LS分布的影响．模拟结果表明对流层顶的季节变化对UT/LS的臭氧分布有明显的影响，臭氧的局地变化可以超过10％在冬季北半球中纬度对流层顶高度升高1km时，模式结果表明对臭氧分布的影响比较显著，局地变化可超过6％，但是对臭氧总量的影响较小，变化不超过5DU，小于观测资料统计分析的结果。     

用全球原始方程半谱模式研究QBO对行星波传播的影响

本文建立了一个全球原始方程半谱模式,模拟了赤道上空风场准两年振荡(QBO)及其相应的副热带急流大小对冬季半球行星波向上传播及平流层突然增温的影响。结果表明,波数1的行星波在QBO东风相比西风相更易向上传播,平流层增温更快更强。波数2则相反。QBO对低纬对流层里的行星波上传的影响限制在低纬低平流层,对中高纬影响不大。     

平流层爆发性增温期间大气变化特性的COSMIC掩星观测

利用高精度和高垂直分辨率的COSMIC掩星观测资料, 详细深入分析了2007年冬---2008年春平流层爆发性增温(SSW)期间10~60 km高度范围内大气的变化特性, 尤其是上平流层和低中间层大气的变化特性. 结果表明, 在SSW过程中, 温度场、风场和剩余环流都发生了明显的变化. 根据温度在主增温前和主增温盛期的变化特性, 在水平方向, 大约以55oN为界, 在垂直方向, 大约以42 km为界, 可以将温度场在纬度-高度的分布分为4个区域: 高纬下层增温区, 增温幅度约高达25 K; 高纬上层降温区, 降温幅度约达30\,K; 中纬下层降温区, 降温幅度约为几K; 中纬上层增温区, 增温也约为几K. SSW期间上下层大气纬向风场的变化规律基本相同. 在纬度方向以45oN为界, 45oN以北地区的西风减弱东风增强, 风场变化高达50 m/s; 45oN以南地区西风增强东风减弱, 变化幅度比较小, 约10 m/s. 在2008年1月下旬到2月底, 大气温度和纬向风有明显的振荡现象, 周期约为12天. 剩余环流的环流圈在SSW期间会发生反转, 由此也表明, SSW期间大气中物质的输运方向也会发生改变.      

平流层冬季增温及大气中的行星波

本文利用NIMBUS-7SAMS资料分析了东经100度子午线上的两个站点(67.5°N和42.5°N)在10mb和0.0827mb高度上从1978年底至1982年间的大气温度,获得几年的平流层冬季增温结果.在1978/1979年和1981年初的冬季,高纬站点几天内出现的平流层增温最大幅度可达65K.对平流层增温的谱分析结果指出,在高纬冬季平流层有很强的16天、32夭、21天周期的行星波。中纬冬季平流层增温幅度较小,约为20K.中纬的中间层高度上整年存在有5天、8天和16天的行星波。分析研究、南、北半球不同纬度的温度随经度的分布,得出高纬冬季平流层、中间层大气温度随经度有明显的变化。波数1和波数2的波有大的幅度(主要是波数1),从高纬到低纬,波幅逐渐减小在冬季的平流层和中间层大气中,波数1和波数2的行星波在短期内可强烈增强,引起平流层冬季增温。      

平流层臭氧和辐射场的季节分布特征

利用美国NCAR化学气候耦合模式WACCM3对平流层温度场、风场、臭氧及辐射场进行了模拟.结果表明,在适宜飞艇长期驻留的准零风层高度20～22km(对应大气压强范围为50～30hPa,以下均采用气压值表征对应大气高度),7-8月风速小于5m·s-1的风带可长期稳定在40°N以北.臭氧空间分布显示,在30hPa气压高度处中国地区臭氧浓度出现了带状分布,30hPa高度以下低纬度地区臭氧浓度低于中纬度地区.平流层太阳加热率的时空变化表明,在平流层上层,太阳加热率可达100×10-6K·s-1,而在平流层下层,只有10×10-6K·s-1.6-8月中国区域的太阳加热率大于9月;在100～30hPa高度内,中纬度地区太阳加热率高于低纬度地区,在30hPa高度以上,低纬度地区太阳加热率高于中纬度地区;8-9月30～40hPa高度处,太阳加热率的空间变化较小.在30hPa高度上,太阳加热率在40°N昼夜变化最大;50hPa高度处,太阳加热率的昼夜变化小于30hPa高度处,而且白天太阳加热率出现极大值的纬度明显靠北.平流层低纬度地区的长波加热率小于中纬度地区.青藏高原由于地形特殊,其6-7月的臭氧浓度、太阳加热率和长波加热率均小于同纬度其他地区.      

低平流层温度对银河系宇宙线强度变化的响应

选用芬兰中子堆监测站从lop年7月至1989年3月的宇宙线强度月平均曲线数据,和在相对应期间我国境内海拉尔等4个高空气象观测站的30hPa和100hPa等位势高度上常规气温观测月平均资料,经统计分析,取得初步结果:低平流层气温与银河系宇宙线辐射强度之间呈现负相关的特性;与银河系宇宙线辐射强度峰区和谷区相对应会在低平流层中引起幅值为2-3℃的温度变化;不同纬度观测站所得观测数据表明,上述增温幅值随纬度降低而减少。      

Temperature and pressure variability in mid-latitude low atmosphere and stratosphere-ionosphere coupling

This study presents the continuation of our previous analysis of variations of atmospheric and space weather parameters above Iberian Peninsula along two years near the 24th solar cycle maximum. In the previous paper (Morozova et al., 2017) we mainly discussed the first mode of principal component analysis of tropospheric and lower stratospheric temperature and pressure fields, which was shown to be correlated with lower stratospheric ozone and anti-correlated with cosmic ray flux. Now we extend the investigation to the second mode, which suggests a coupling between the stratosphere and the ionosphere.This second mode, located in the low and middle stratosphere (and explaining ~7% of temperature and ~3% of geopotential height variations), showed to be statistically significantly correlated with variations of the middle stratosphere ozone content and anti-correlated with variations of ionospheric total electron content. Similar co-variability of these stratospheric and ionospheric parameters was also obtained with the wavelet cross-coherence analysis.To investigate the role of atmospheric circulation dynamics and the causal nature of the found correlations, we applied the convergent cross mapping (CCM) analysis to our series. Strong evidence for the stratosphere-ionosphere coupling were obtained for the winter 2012–2013 that is characterized by the easterly QBO phase (quasi-biennial oscillations of the direction of the stratospheric zonal winds) and a strong SSW (sudden stratospheric warming event). Further analysis (for the three-year time interval 2012–2015) hint that SSWs events play main role in emphasizing the stratosphere-ionosphere coupling.     

Responses of the upper middle atmosphere (60–110 km), to the first two stratwarms of map (1982/3, 1983/4)

The global developments of the stratospheric events (～20–50 km) are briefly described using balloon and satellite data. Winds data from L.F. drift (52°N, 15°E, Europe) for heights of 90–100 km, and from M.F. radar (52°N, 107°W, Canada) for heights of 60–110 km are then compared with the stratospheric morphology.Data for 1982/3 and 1983/4 show that the planetary wave activity and warmings produced strong westward and southward perturbations in the radar winds. Satellite data from 0.1, 0.01 hPa are consistent with these winds; and also show smaller scale structures in the mesosphere than the stratosphere. The semi-diurnal tide responded strongly to the atmospheric disturbances in Europe and Canada: for the latter vertical wavelength changes occurred for heights of 70–100 km. However the correlation between these tidal fluctuations was not high indicating that the tidal adjustments were continental rather than hemispheric.     

人为活动对高平流层,中间层大气的影响

利用一维光化、辐射耦合模式研究了人为活动所排放出的废弃物ＣＨ４、Ｎ２Ｏ和ＣＯ２含量增加对高平流层，中间层大气的影响。结果指出，对流层中这些气体增加一倍将导致上中层大气水汽、Ｏ３和温度的明显变化。ＣＯ２含量增加将使上中层温度降低约１０Ｋ；而ＣＨ４含量的加倍不仅使中层顶附近水汽含量增加５０％以上，也使其温度有更明显的下降，这将更有利于於光云的形成。     

The variability of stratospheric nitrogen compounds observed by LIMS in the winter of 1978–1979

The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O₃, H₂O, NO₂, and HNO₃. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO₂ and HNO₃, are important elements in the NO_x chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred.     

Complex organics in laboratory simulations of interstellar/cometary ices.

We present the photochemical and thermal evolution of both non-polar and polar ices representative of interstellar and pre-cometary grains. Ultraviolet photolysis of the non-polar ices comprised of O2, N2, and CO produces CO2, N2O, O3, CO3, HCO, H2CO, and possibly NO and NO2. When polar ice analogs (comprised of H2O, CH3OH, CO, and NH3) are exposed to UV radiation, simple molecules are formed including: H2, H2CO, CO2, CO, CH4, and HCO (the formyl radical). Warming produces moderately complex species such as CH3CH2OH (ethanol), HC(=O)NH2 (formamide), CH3C(=O)NH2 (acetamide), R-CN and/or R-NC (nitriles and/or isonitriles). Several of these are already known to be in the interstellar medium, and their presence indicates the importance of grain processing. Infrared spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry demonstrate that after warming to room temperature what remains is an organic residue composed primarily of hexamethylenetetramine (HMT, C6H12N4) and other complex organics including the amides above and polyoxymethylene (POM) and its derivatives. The formation of these organic species from simple starting mixtures under conditions germane to astrochemistry may have important implications for the organic chemistry of interstellar ice grains, comets and the origins of life.     

Temperature variability in the tropical mesosphere during the northern hemisphere winter

Temperature observations at 20–90 km height and 5°N–15°N during the period of December 1992–March 1993 from the WINDII and MLS experiments on the UARS satellite are analysed together with MF radar winds and UKMO assimilated fields of temperature and zonal and meridional winds. The correlation between the different datasets at the tropics and zonal mean wind data at mid latitudes is examined for period February–March 1993, when series of stratospheric warming events were observed at middle and high latitudes. Wavelet analysis is applied to investigate coupling between stationary and travelling planetary waves in the stratosphere and the upper mesosphere. Planetary waves m = 1 with periods of 4–7 days, 8–12 days and 13–18 days are found to dominate the period. Westward 7- and 16–18 day waves at the tropics appear enhanced by stationary planetary waves during sudden stratospheric warming events.     

Stratospheric trace gas distributions observed in different seasons

A newly developed balloon-borne cryogenic sampler has been used to collect large air samples in the midlatitude stratosphere (44° N). The samples were analysed for their content of several longlived trace gases. The vertical profiles of N₂O, CH₄, and CF₂Cl₂ derived from two balloon flights in winter 1982 and, as part of the MAP Globus Project, in fall 1983 indicate variations that are caused by large scale dynamic processes. Significant features of the profiles are discussed and compared with averaged profiles that were derived from a series of balloon sampling flights performed previously over the same location during the summer season. The temporal variation of the individual profiles is more detailed than predicted by model calculations.     

Middle atmosphere summer duration as an indicator of long-term circulation changes

Summer duration (SD) is defined here as the time interval between spring and autumn turn around of zonal winds in the stratosphere. SD long-term trends are obtained from analysis of middle stratosphere NCEP and ECMWF data. They are found to be dependent on latitude and altitude. Wind data are available since 1948. The corresponding analysis suggests a breakpoint in the trend at around 1980: SD increases before 1980, and decreases afterwards. Corresponding changes of stratospheric wave activity are analyzed and found to be a major contribution to the SD trends. Long-term computer runs of the Whole Atmosphere Community Climate Model (WACCM 1b) are consistent with these results. Vegetation data on the ground indicate similar trends with a break.     

The atmosphere of the primitive earth and the prebiotic synthesis of organic compounds.

The prebiotic synthesis of organic compounds using a spark discharge on various simulated prebiotic atmospheres at 25 degrees has been studied. Methane mixtures contained H2 + CH4 + H2O + N2 + NH3 with H2/CH4 molar ratios from 0 to 4 and pNH3 = 0.1 torr. A similar set of experiments without added NH3 was performed. The yields of amino acids (1.2 to 4.7% based on the carbon) are approximately independent of the H2/CH4 ratio and the presence of added NH3, and a wide variety of amino acids are obtained. Mixtures of H2 + CO + H2O + N2 and H2 + CO2 + H2O + N2, with and without added NH3, all give about 2% yields of amino acids at H2/CO and H2/CO2 ratios of 2 to 4. For the H2/CO and H2/CO2 ratios less than 1, the yields fall off drastically to as low as 10(-3)%. Glycine is almost the only amino acid produced from CO and CO2 atmospheres. These results show that the maximum yield is about the same for the three carbon sources at high H2/carbon ratios, but that CH4 is superior at low H2/carbon ratios. In addition, CH4 gives a much greater variety of amino acids than either CO or CO2. If it is assumed that amino acids more complex than glycine were required for the origin of life, then these results indicate the need for CH4 in the primitive atmosphere. The yields of cyanide and formaldehyde parallel the amino acid results, with yields of HCN and H2CO as high as 13% based on the carbon. Ammonia is also produced from N2 in experiments with no added NH3 in yields as high as 4.9%. These results show that large amounts of NH3 would have been synthesized on the primitive earth by electric discharges. The amount of ammonia formed by hydrolysis of HCN and various nitriles may have exceeded that formed directly in electric discharges.