Validation of the Atmospheric Infrared Sounder Retrieval Products over China and Their Application in Numerical Mode

The atmospheric infrared sounder (AIRS) instrument onboard Aqua Satellite is a high spectral resolution infrared sounder. In recent years, AIRS has gradually become the primary method of atmospheric vertical observations. To examine the validation of AIRS retrieval products (V3.0) over China, the AIRS surface air temperature retrievals were compared with the ground observations obtained from 540 meteorological stations in July 2004 and January 2005, respectively. The sources of errors were considerably discussed. Based on the error analysis, the AIRS retrieved surface air temperature products were systemically corrected. Moreover, the AIRS temperature and humidity profile retrievals were compared with T213 numerical forecasting products. Because T213 forecasting products are not the actual atmospheric states,to further verify the validation, the AIRS temperature and humidity profile products were assimilated into the MM5 model through the analysis nudging. In this paper, the case on February 14, 2005 in North China was simulated in detail. Then, we investigated the effects of AIRS retrievals on snowfall, humidity field,vertical velocity field, divergence field, and cloud microphysical processes. The major results are: (1) the errors of AIRS retrieved surface air temperature products are largely systematic deviations, for which the influences of terrain altitude and surface types are the major reasons; (2) the differences between the AIRS atmospheric profile retrievals and T213 numerical prediction products in temperature are generally less than 2 K, the differences in relative humidity are generally less than 25%; and (3) the AIRS temperature and humidity retrieval products can adjust the model initial field, and thus can improve the capacity of snowfall simulation to some extent.     

国际卫星红外大气探测器发展新特点

为了深入了解国际卫星红外大气探测仪器的新特点,推动其资料应用,以美国NASA Aqua卫星装载的高光谱红外大气探测仪器AIRS(Atmospheric Infrared Sounder)为例,介绍卫星红外探测仪研发背景、仪器特征、研制技术、数据产品处理和应用。研究表明,AIRS开辟了卫星大气探测的新时代,它为其他未升空的高光谱仪器提供了不可或缺的研究资料,对将装载于我国风云卫星的高光谱红外大气垂直探测仪器的研制具有重大的参考价值。     

两种红外晴空辐射订正方法及其反演大气参数的比较

比较了目前开发的两种红外晴空辐射订正算法：1）匹配的红外和微波探测值融合的算法,如AIRS／AMSU晴空订正算法（大气红外探测器AIRS,先进的微波探测器AMSU）;2）匹配的红外成像与探测值融合的算法,如AIRS／MODIS晴空订正算法（中分辨率光谱成像仪MODIS）。结果表明,相对于MODIS的晴空观测值而言,AIRS／MODIS晴空订正算法优于AIRS／AMSU晴空订正算法,而且AIRS／MODIS晴空订正辐射值反演的大气温湿廓线与欧洲中期天气预报中心（ECMWF）的客观分析场更接近;尽管这两种晴空订正算法本质上相当不同,但都是有效且互补的,当微波探测资料不能获得时,融合红外成像仪和探测器资料就成为唯一可靠的、间接使用有云影响的红外观测值的办法。     

A Neural Network Based Single Footprint Temperature Retrieval for AtmosphericInfrared Sounder Measurements and Its Application to Study onStratospheric Gravity Wave

Satellite hyperspectral infrared sounder measurements have better horizontal resolution than other sounding techniques as it boasts the stratospheric gravity wave(GW) analysis. To accurately and efficiently derive the three-dimensional structure of the stratospheric GWs from the single-field-of-view(SFOV) Atmospheric Infra Red Sounder(AIRS) observations, this paper firstly focuses on the retrieval of the atmospheric temperature profiles in the altitude range of 20-60 km with an artificial neural...     

利用高光谱红外探测资料反演大气参数

文章介绍了红外高光谱的卫星探测技术以及利用现有的机载和星载高光谱资料的反演方法，着重讨论了美国NASA地球观测系统上携带的大气红外探测仪AIRS的反演方法。     

青藏高原上空甲烷的时空分布特征及其夏季高值形成机制分析

利用搭载在美国Aqua卫星上的大气红外探测仪(AIRS)观测资料反演的全球甲烷(CH_4)产品和NCEP再分析资料,分析了2003~2014年青藏高原上空CH_4的时空变化特征,探讨了夏季CH_4高值变化与季风的关系。研究结果表明:就青藏高原整体而言,CH_4浓度随高度增加递减;对流层中高层CH_4含量季节变化较为明显,其平均浓度在7~9月处于高值,6月、10月次之,其余月份处于低值。2003~2014年CH_4含量呈逐年上升趋势,年增长率约为4.66ppb(10-9)。高原上空CH_4空间分布分析显示,高原北部CH_4浓度高于南部地区。夏季风期间,随着高原上的强对流输送和上空南亚高压的阻塞,对流层中高层CH_4浓度明显增加并不断积累,在8月底至9月初出现最大值。在分析季风指数的基础上发现,夏季季风影响下的强对流输送是高原对流层中高层CH_4高值形成的主要原因之一,对流层中高层CH_4浓度最大值出现时间较季风指数的峰值滞后约半至一个月,随着夏季风的撤退,CH_4浓度高值迅速降低。     

青藏高原地区大气红外探测器（AIRS）资料质量检验及揭示的上对流层水汽特征

上对流层水汽（UTWV）是大气中最重要的温室气体,对全球气候变暖有重要贡献; 而青藏高原被认为是UTWV进入平流层的重要通道,在平流层－对流层水汽交换及平流层水汽变化中扮演着重要角色。首先利用高原探空站资料对大气红外探测器（AIRS）反演的水汽数据在高原地区的质量进行了检验,发现AIRS反演的水汽数据与探空实测数据是相当一致的。其中全年和夏半年AIRS的可信度较好,而冬半年,尤其是上对流层AIRS水汽可信度相对较低,但在缺乏高精密数据时仍部分可用。利用AIRS资料对青藏高原地区UTWV季节变化特征进行了分析,结果表明,高原冬季偏干,而夏季显著偏湿,并且空间分布具有明显的不均匀性。经验正交函数(EOF)分析显示,夏季高原UTWV主要存在三种空间分布型,即全区一致型,高原东西偶极型和南北带状偶极型。一致型分布具有明显的季节变化,而偶极型则以季节内振荡为主。在此基础上,重点研究夏半年高原地区UTWV季节内振荡特征,结果表明,UTWV季节内振荡的显著周期位于10～20天和30～60天。前者主要表现为纬向东传,并且可以越过高原进入我国江淮流域上空;而后者主要向南移动,基本表现为高原局地振荡。最后,进一步探讨了高原UTWV季节内振荡的可能机制,结果表明,高原地区UTWV的低频变化主要与高原热状况、南亚高压活动及其与二者相耦合的对流活动有关。     

利用红外辐射光谱反演大气CO2浓度的理论研究

依据最新的大气分子光谱数据集（HITRAN 2004）,利用逐线积分辐射传输模式,模拟计算了大气顶射出红外辐射光谱及其对大气CO2浓度变化的灵敏度,发现：大气CO24．3μm吸收带,特别是2241-2249cm^-1、2250-2258cm^-1、2259-2267cm^-1和2382—2390cm^-1波段射出的红外辐射,随CO2浓度的增加而显著降低,且很少受其他大气成分变化干扰,因此特别适于用来遥感探测大气CO2浓度的变化。根据最优非线性反演方法,反演获得了0-15km的大气CO2廓线,结果表明,利用上述4个通道的红外辐射值,可精确反演出自由对流层的CO2浓度变化。     

Numerical Study on Microphysical Processes of Two Different Snowfall Cases in Northern China

In this paper,two snowfall cases under different weather conditions in northern China are simulated by using the meso scale model MM5.Two-way nesting structure of domains is designed for each case.Among the explicit schemes of MM5,the Reisner graupel scheme is selected to describe the microphysical process. The simulated snow-bands of two cases are basically consistent with observations.The simulated results of microphysical processes are mainly discussed.The hydrometeors and their sources and sinks under different weather backgrounds are described.The feedback effects of microphysical processes on the thermal and dynamic processes are also discussed.Method that outputs the accumulative sources and sinks per hour is used to analyze the distribution characteristics of hydrometeors during the strongest snowfall period.Two sensitivity tests (called heat test and drag test) are conducted to examine the effects of microphysical pro- cesses on cloud produced by the latent heat and drag force. Results have shown that the distribution of particles has a close relation with temperature.The tem- perature of Beijing snowfall is under 0℃and there exist vapor and solid phase particles,while Liaoning snowfall has vapor,liquid,and solid phase particles due to the warm temperature.The distribution of these particles is not the same at different development stages.From the analyses of the characteristics of sources and sinks,it is found that snow is mainly produced by the deposition and accretion with ice.Cloud water is crucial to graupel.The melting of ice-phase particles enhances the rain production.The results of heat tests and drag tests reveal that the microphysical processes have interacted with the dynamic and thermal processes.Latent heat release of hydrometeors feeds back positively on snowfall while the drag force not. At last,comparisons of simulated results have been done between the two different kinds of snowfall cases. The microphysical processes of Liaoning snowfall case is more complicated than those of Beijing snowfall case.The values of the cloud variables are larger and the interactions between the microphysical processes and the thermal and dynamic processes of Liaoning snowfall case are stronger than those of Beijing snowfall case.     

Validation of the Polar MM5 for use in the simulation of the Arctic river basins

The simulations were performed using a modified mesoscale model,the Polar MM5,which was adapted for use within polar regions.The objective of the study was to illustrate the skill of the Polar MM5 in simulating atmospheric behavior over the Arctic river basins.Automatic weather station data,global atmospheric analyses,as well as near-surface and upper-air observations were used to verify the simulation. Parallel simulations of the Polar MM5 and the original MM5 within the period 19-29 April 1997 simula- tions revealed that Polar MM5 reproduced better near-surface variables forecasts than the original MM5 for the region located over the North American Arctic regions.The well predicted near-surface temperature and mixing ratio by the Polar MM5 confirmed the modified physical parameterization schemes that were used in this model are appropriate for the Arctic river regions.Then the extended evaluations of the Polar MM5 simulations over both the North American and Eurasian domains during 15 December 2002 to 15 May 2003 were then carried out.The time series plots and statistical analyses from the observations and the Polar MM5 simulations at 16 stations for the near-surface and vertical profiles at 850 hPa and 500 hPa variables were analyzed.The model was found to reproduce the observed atmospheric state both at magnitude and variability with a high degree of accuracy,especially for temperature and near-surface winds,although there was a slight cold bias that existed near the surface.     

我国东部夏季一次强对流活动过程中对流层上部大气成分变化的分析

利用星载微波临边遥感探测结果,对2006年6月28～29日江淮地区的一次强对流天气过程中对流层上部一氧化碳 (CO) 、臭氧 (O₃) 、水汽 (H₂O) 和冰水含量 (IWC) 的分布特点进行了研究.强对流天气过程前后的对比分析表明,CO混合比增大,在200 hPa处增加了0.12 ppm (1 ppm=10-6);O₃混合比减小,在70 hPa处减少了0.30 ppm;H₂O混合比在250 hPa处增加了400 ppm;IWC在强降水发生之前有大幅增长,在200 hPa处最大含量可达0.03 g/m3.CO和O₃含量与垂直运动速度两者的相关变化表明,对流垂直输送作用可能是造成对流层上层和平流层低层大气成分变化的机制之一.而H₂O和IWC含量的增加主要局限于对流层顶以下,这表明对流层上部水物质的质量和形态是由垂直输送作用和对流系统内部的微物理过程共同决定的.     

锋面结构的MM5数值模拟

利用美国PSU／NCAR具有嵌套功能的非静力中尺度大气模式MM5，对发生在2000年4月8-9日的一次强冷锋进行数值模拟。分析模拟结果发现，锋面结构的演变与适应锋生理论相一致，并且具有一种不连续结构。     

人工神经网络算法在红外高光谱资料反演大气温度廓线中的应用

基于红外高光谱大气探测器AIRS实况观测资料,尝试用人工神经网络算法来实现晴空时大气的温度垂直廓线反演,重点将该算法与目前已经发展比较成熟的特征向量统计反演算法进行比较。结果表明,两种算法在计算时间效率和反演精度上相当。鉴于人工神经网络算法的统计物理本质,误差反向传播BP神经网络可以求解非线性问题,在优化训练样本和继续调试网络种类和网络参数的基础上,有望能进一步提高反演精度。     

新疆博湖地区大气向下红外辐射特性及其对云识别应用的研究

为加强新疆戈壁地区云的自动观测,利用辐射传输模式SBDART和新疆博湖地区历史气候资料,分析了当地大气向下红外辐射对大气影响因子的敏感性和利用全天空红外辐射进行云识别分类的可行性,并提出了一种基于典型云族红外阈值的云分类方法。结果表明：（1）水汽、云、天顶角、能见度等对中红外波段向下红外辐射值都有较大影响;（2）当能见度较差时,气溶胶对向下红外辐射的贡献不可忽略,并由于局地气溶胶辐射特性难以确定,因此是利用天空向下红外辐射进行云识别时的一个不确定因素;（3）根据8～14μm波段不同云族的辐射特性差异分析,阈值法是进行云识别和云族区分的有效方法。但该方法应用效果的好坏依赖于实测探空数据和历史气候数据的有效性及准确性。     

水、陆不均匀条件下大气边界层结构的模拟研究

应用2004年白洋淀野外观测实验资料,对白洋淀地区水、陆不均匀分布条件下的大气边界层开展了数值模拟试验,结果表明:由于下垫面的热力差异,在360多km2的白洋淀地区,地表特征分布的不均匀可以引发弱的局地环流,影响大气边界层内温度和湿度的空间分布;在500m高度以下,下垫面不均匀分布对湍流动能有明显影响.最后将模拟结果与观测资料进行了对比检验.     

改进的FY-3B/VIRR OLR反演模式及其应用效果

FY-3B卫星VIRR仪器的向外长波辐射(outgoing long-wave radiation,OLR)产品处理采用与NOAA/AVHRR相同的算法模型,即用窗区通道亮温-通量等效亮度温度的回归关系式计算OLR,但两星的OLR业务产品与目前国际质量最好的云和地球辐射能量系统(cloud and earth’s radiant energy system,CERES)仪器观测OLR产品相比,存在约10 W·m~(-2)的系统负偏差。FY-3B的原因在于OLR反演模式建立过程中红外辐射传输计算软件的精度不够。鉴于此,本文采用美国21世纪开发的逐线辐射传输模型计算软件(LBLRTM),模拟计算了全球2521条大气廓线的大气顶辐射率光谱,在此基础上计算了每条廓线的OLR和FY-3B/VIRR窗区通道亮温,应用最小二乘法统计回归模拟数据,重新建立了由FY-3B/VIRR窗区通道亮温计算OLR的回归关系式及系数。模式应用于FY-3BL1级数据,处理2016年1,3,7和10月的FY-3B逐日全球OLR资料,该资料与AQUA-TERRA卫星的CERES仪器OLR观测产品相比,得到日平均OLR:RMSE=9~15 W·m~(-2),R=0.9834,Bias=-0.3W·m~(-2);月平均OLR:RMSE=4~7W·m~(-2),R=0.9915,Bias=-0.3W·m~(-2),表明改进的模式能处理出无系统偏差的、精度基本与CERES观测相当的OLR产品,尽管单通道反演算法有着固有的模式回归误差。     

变分伴随方法应用于大气化学初值和参数反演研究

将结合正则化思想的变分伴随方法应用于大气平流层中臭氧破坏催化反应过程的浓度初始值和反应速率参数的反演问题,推导了在整体资料和末端时刻局部资料反演的伴随模式和泛函梯度,并进行了一组理想数值试验.试验结果表明了变分伴随方法运用于大气化学过程的反演研究的有效性,特别是局部资料联合反演中可以运用正则化思想克服反演的不适定性.     

2014年海洋和大气环流异常及对中国气候的影响

本文基于实时、历史观测资料和再分析资料,综合分析2014年海洋和大气环流异常特征,并讨论这些异常特征对中国气候的主要影响。分析表明：2013/2014年冬季,极涡偏向西半球,东亚冬季风和西伯利亚高压均偏弱,导致我国冬季气温总体偏高。受冬季风强度季节内变化影响,前冬暖、后冬冷。2014年赤道中东太平洋形成一次厄尔尼诺事件,4月以来热带印度洋全区一致海温模态正位相维持发展,受暖海温外强迫影响,夏、秋季西太平洋副热带高压强度偏强、位置偏南,主汛期我国东部降水呈“北少南多”型异常分布。2014年南海夏季风爆发异常偏晚,强度偏弱。东亚夏季风强度偏弱,有利于我国东部主汛期雨带偏南,江南梅雨区和长江中下游梅雨区梅雨量偏多,北方大部夏季降水偏少。