渤海海洋悬浮泥沙二元特征参数MODIS遥感反演模型研究

This paper brought out a new idea on the retrieval of suspended sediment concentration, which uses both the water-leaving radiance from remote sensing data and the grain size of the suspended sediment. A principal component model and a neural network model based on those two parameters were constructed. The analyzing results indicate that testing errors of the models using the two parameters are 0.256 and 0.244, while the errors using only water-leaving radiance are 0,384 and 0.390. The stability of the models with grain size parameter is also better than the one without grain size. This research proved that it is necessary to introduce the grain size parameter into suspended sediment concentration retrieval models in order to improve the retrieval precision of these models.     

南岳雨凇分析

分析了南岳雨凇与冷冬及西太平洋副热带高压的关系。结果表明,在冷冬年份,南岳雨凇日数偏多;在暖冬年份,南岳雨凇日数偏少。西太平洋副热带高压与南岳冬季气温密切相关。副热带高压偏弱时,南岳冬季偏冷;副热带高压偏强时,南岳冬季偏暖。副热带高压的588线北界偏北时,南岳冬季偏暖,反之偏冷。副热带高压的西伸脊点偏东时,南岳雨凇日数偏多,反之偏少,而且西太平洋副热带高压的变化超前于冷暖冬的变化。     

夏半年青藏高原及附近地区30—60天振荡的分布特征

本文用1980—1982年3个夏半年(5—9月)的ECMWF客观分析资料,对青藏高原及其附近500hPa位势高度场进行了最大熵谱分析和滤波分析。结果表明:青藏高原及其附近地区夏半年存在着30-60天振荡,高原东部为一相对的30-60天振荡中心。本文还讨论了振荡的年际变化特征。     

0414号台风“云娜”的数值模拟

利用美国CAPS的非静力高分辨率区域预报模式(ARPS)对0414号台风"云娜"进行数值模拟,其中把新一代多普勒天气雷达资料分析引入模式,模拟结果表明ARPS模式能较好模拟台风"云娜"的移动路径、中心气压强度变化及台风大暴雨;并利用模式输出的组合反射率与雷达组合反射率资料比较来检验模拟结果.数值模拟结果表明台风自身结构是引起0414号台风西折路径的重要原因;浙南闽北地形对0414号台风的影响作地形敏感性试验结果表明浙南闽北地形使0414号台风移动路径出现右偏现象;浙南闽北地形对0414号台风强度影响较小,地形对深入内陆后台风强度变化有较明显的影响;浙南闽北地形对0414号台风暴雨有增幅作用,降水分布更加不均匀.     

Climate Responses to Direct Radiative Forcing of Anthropogenic Aerosols,Tropospheric Ozone,and Long-Lived Greenhouse Gases in Eastern China over 1951–2000

A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to chang- ing concentrations of long-lived greenhouse gases(GHGs,CO2,CH4,N2O),tropospheric O3,and aerosols during the years 1951–2000.Concentrations of sulfate,nitrate,primary organic carbon(POA),secondary organic carbon(SOA),black carbon(BC)aerosols,and tropospheric O3 for the years 1950 and 2000 are obtained a priori by coupled chemistry-aerosol-GCM simulations,and then monthly concentrations are in- terpolated ...     

重庆冰雹气候特征及人工防雹对策

利用重庆34个县1960—2004年的气象志、县志资料及1980—2004年的MICAPS资料,对重庆冰雹的时空分布特征、环流背景、冰雹路径等进行了综合分析。重庆冰雹在空间上存在东多西少的特征,东北部山区是冰雹频发地;近50年冰雹具有"少—多—少-多"的非均匀周期变化趋势,20世纪80年代后明显增多;月际变化呈"双峰型"分布,高峰期为4—5月和7—8月,6月相对较少;重庆冰雹天气以局地对流为主,系统性对流次之,产生系统性对流天气的环流背景分为3类,即低涡型、西北气流型和高空低槽型,其中西北气流型是主要影响系统,约占62%。给出了重庆主要冰雹路径图并提出了人工防雹的对策建议,以提高人影作业的科学性和有效性。     

北京地区雷暴大风日θe平均廓线特征

利用NCEP再分析资料对北京地区1999～2003年7～8月出现的24个雷暴大风日相当位温θe的平均廓线进行了研究。结果表明，在对流层底层有一个θe的极大值，在对流层中层(500～660hPa)θe达到其极小值。     

1980年夏季青藏高原及其附近地区大气中30—60天振荡的时空分布

本文用1980年5—9月ECMWF客观分析资料,对青藏高原上空30—60天振荡进行研究。结果表明,与高原附近30—60天振荡相联系的遥相关波列有两支,一支为高原-伊尔库茨克-欧洲-大西洋东部;另一支为青藏高原-伊尔库茨克-雅库茨克-堪察加半岛-阿留申群岛。30—60天振荡在高原北侧和南侧地区,对流层上层和下层表现出不同的垂直结构。时间变化主要表现为向西的能量频散。     

露点与温度露点差对降雹的指示意义

通过对永登防雹试验基地１９７１￣１９７８年６￣８月０９时６３４次无线电探空资料与地面实况、天气现象进行分类研究,发现露点零度的高度具有指示雹日的意义;３００￣６００ｈＰａ层间的Σ（Ｔ－Ｔｄ）ｉ和３００￣５００ｈＰａ间的Σ（Ｔ－Ｔｄ）ｉ具有指示降雹强弱的意义,为冰雹预报提供依据,具有实用意义。     

A study of air/space-borne dual-wavelength radar for estimation of rain profiles

In this study, a framework is given by which air/space-borne dual-wavelength radar data can be used to estimate the characteristic parameters of hydrometeors. The focus of the study is on the Global Precipitation Measurement （GPM） precipitation radar, a dual-wavelength radar that will operate in the Ku （13.6 GHz） and Ka （35 GHz） bands. A key aspect of the retrievals is the relationship between the differential frequency ratio （DFR） and the median volume diameter, Do, and its dependence on the phase state of the hydrometeors. It is shown that parametric plots of Do and particle concentration in the plane of the DFR and the radar reflectivity factor in the Ku band can be used to reduce the ambiguities in deriving Do from DFR. A self-consistent iterative algorithm, which does not require the use of an independent pathattenuation constraint, is examined by applying it to the apparent radar reflectivity profiles simulated from a drop size distribution （DSD） model. For light to moderate rain, the self-consistent rain profiling approach converges to the correct solution only if the same shape factor of the Gamma distributions is used both to generate and retrieve the rain profiles. On the other hand, if the shape factors differ, the iteration generally converges but not to the correct solution. To further examine the dual-wavelength techniques, the selfconsistent iterative algorithm, along with forward and backward rain profiling algorithms, are applied to measurements taken from the 2nd generation Precipitation Radar （PR-2） built by the Jet Propulsion Laboratory. Consistent with the model results, it is found that the estimated rain profiles are sensitive to the shape factor of the size distribution when the iterative, self-consistent approach is used but relatively insensitive to this parameter when the forward- and backward-constrained approaches are used.