大气红外间接遥测方程的估计解和验前限制

在线性估计调整方法中研究如何考虑验前信息的方法,是发展估计算法的重要途径.为此,在文中根据十五通道理论权重函数和五个不同估计方法所得到的模拟数值试验结果,从估计模式所涉及的信息形式、不同形式验前限制的效应以及估计解的实际可解性等对估计解的精度和验前限制的内在联系进行了数值分析,确认TPRD1的解和验前信息之间具有最佳的统计结构.     

基于秒级探空资料的中国地区浮力频率分布

浮力频率用来描述大气层结稳定性,反映大气扰动强弱。利用2014年6月-2017年5月中国地区高垂直分辨率的秒级探空资料,分析了中国地区浮力频率的时空分布特征。结果表明:中国地区大气浮力频率总体随高度的增加而增大,低平流层值大于对流层值;对流层和低平流层中浮力频率随高度变化均较小可视为常数,过渡层浮力频率随高度变化较大,对流层中浮力频率受地形影响较平流层大。对流层中北方地区5 km高度以下的浮力频率随时间呈现出较弱的周期变化,周期为1年,峰值出现在冬季,南方地区随时间无明显变化;在过渡层中南北地区的浮力频率随时间均呈现出1年的周期变化,峰值出现在冬季,谷值出现在夏季;在低平流层中南北地区浮力频率随时间均无明显变化。浮力频率的大小变化对重力波参数有较大影响,秒级探空资料计算的的浮力频率和风速切变更精细,较常规探空资料更准确地反映大气稳定度的变化。     

2007年西北太平洋热带气旋活动综述

利用热带气旋年鉴、海温和大气环流再分析资料,分析2007年西北太平洋(包括南海)的风暴级以上热带气旋(简称TC)活动状况及海-气条件.结果表明,相对于气候平均值,2007年西北太平洋TC活动的季节峰期推后了约2个月,源地明显偏北,生成点纬度发生了2次明显跃变,年度TC的总体活动较弱,但个体的强度较强,路径以西北行为主,登陆比例偏大.影响上述TC活动特征的一个重要原因是年内ENSO循环的位相使得上半年的大气环流不利因素居多,而下半年大尺度上升运动、热带辐合带均较强,副高偏北、局地垂直风切变较小和对流层低层较强的扰动活动等条件,也十分有利热带气旋活动.     

基于极坐标投影的多谱勒雷达数据栅格化技术

通过研究球面距离算法、极坐标投影原理及新一代多谱勒天气雷达产品的数据存储格式,实现精度较高的雷达数据栅格化,为雷达回波追踪、降水算法优化、短时临近预报等相关的应用与研究提供经过仰角订正、球面距离订正后的更准确更通用的产品数据.     

气团分类及其与贵州气候灾害的关系

通过对贵州3站点历年逐日地面气象要素进行统计分类，分析影响贵州的气团活动规律，并对贵州气候灾害与各类气团活动频数作相关分析。结果表明：贵州气候受多种气团活动的影响，各型气团对应特定的天气特征及一定的环流背景。另外，气候灾害与某些气团活动变化具有很好的相关性，这对进一步研究贵州气候变化及气候灾害成因具有一定的现实意义。     

Characteristics of carbonyl compounds in ambient air of Shanghai,China

The levels of carbonyl compounds in Shanghai ambient air were measured in five periods from January 2007 to October 2007 (covering winter, high-air-pollution days, spring, summer and autumn). A total of 114 samples were collected and eighteen carbonyls were identified. Formaldehyde, acetaldehyde and acetone were the most abundant carbonyls and their mean concentrations of 19.40 ± 12.00, 15.92 ± 12.07 and 11.86 ± 7.04 μg m⁻³ respectively, in the daytime for five sampling periods. Formaldehyde and acetaldehyde showed similar diurnal profiles with peak mixing ratios in the morning and early afternoon during the daytime. Their mean concentrations were highest in summer and lowest in winter. Acetone showed reversed seasonal variation. The high molecular weight (HMW, ≥C5) carbonyls also showed obvious diurnal variations with higher concentrations in the daytime in summer and autumn, while they were all not detected in winter. Formaldehyde and acetaldehyde played an important role in removing OH radicals in the atmosphere, but the contribution of acetone was below 1%. The carbonyls levels in high-air-pollution days were reported. More carbonyl species with higher concentrations were found in high-air-pollution days than in spring. These carbonyls were transported with other pollutants from north and northwest in March 27 to April 2, 2007 and then mixed with local sources. Comparing with Beijing and Guangzhou, the concentrations of formaldehyde and acetaldehyde in Shanghai were the highest, which indicated that the air pollution in Shanghai was even worse than expected.     

两种反映东亚夏季风异常的指数的比较研究

本文利用文献^ [4]提出的一种新的反映东亚夏季风异常的海陆温差指数分析了夏季风异常时我国气温、降水异常以及东亚环流状况，通过分析指出，东亚夏季风偏强，则中国东部夏季气温偏高，江淮干旱，华北多雨；夏季风偏弱则夏季气温偏低，江淮多雨，易涝，华北少雨。通过两种夏季风指数的对比，海陆温差指数能更好地反映东亚夏季环流及天气气候异常。文中还指出，海陆温差指数能更好的反映夏季风异常的原因是它的定义方法更科学，更全面的反映东亚海陆热力差异，既包含了东亚纬向海陆热力差异的影响，又考虑了东亚经向海陆热力差异的因素，并用地表气温和海表温度差来表示海陆热力差，好于以往用海平面气压差来反映海陆热力差。     

Comparison of manual and automatic methods for measurement of methane emission from rice paddy fields

The methane emission flux from rice paddies was simultaneously measured with automatic and manual methods in the suburban of Suzhou. Both methods were based on the static chamber/ GC-FID techniques. Detail analysis of the experimental results indicates: a) The data of methane emission measured with the automatic method is reliable. b) About 11 or 19 o’clock of local time is recommended as the optimum sampling time for the manual spot measurement of methane emission from rice paddies. The methane emission fluxes measured by manual sampling at local time other than the optimum time have to be corrected. The correction coefficient may be determined by automatic and continuous measurement. c) In order to get a more accurate result, an empirical correction factor, such as 18%, is recommended to correct the seasonally total amount of measured methane emission by enlarging the au-tomatically measured data or reducing the manually measured ones.     

近百年来湖泊有机碳与无机碳埋藏响应流域开发的协同变化——以石林喀斯特地区为例

有机碳和无机碳的流域输出是湖泊碳埋藏的重要驱动因子,而喀斯特地区无机碳循环具有反应迅速且对人类活动影响敏感的特点.在流域开发持续增强的背景下,喀斯特地区湖泊有机碳和无机碳的来源、含量与埋藏通量可能会出现同步变化的协同模式.本文以云南省石林喀斯特地区流域土地利用类型不同的两个中型湖泊(长湖、月湖)开展对比分析,通过对沉积物钻孔的土壤侵蚀强度(磁化率)、流域外源输入(C:N比值)、水动力(粒度)、营养盐(总氮、总磷)、藻类生产力(叶绿素色素)等代用指标的分析,结合监测数据和历史资料重建了两个湖泊环境变化的近百年历史,并定量识别了有机碳和无机碳埋藏响应流域开发的变化特征与协同模式.沉积物磁化率和C:N比值结果揭示了流域地表侵蚀和外源输入的阶段性特征,同时总氮和总磷含量记录了长湖和月湖营养水平上升的长期模式.在流域森林覆被较高(33.43%)的长湖中,全岩和有机质C:N比值分别与磁化率信号呈显著正相关(r=0.95和0.89,P<0.001),且与无机碳和有机碳含量呈显著负相关(r=-0.94,P<0.001和r=-0.52,P=0.01),反映了森林植被退化时流域碳输出的减少对沉...