气候适宜度国内外研究进展及展望

简要概述了国外在气候适宜度方面的研究现状,回顾了我国在气候适宜度方面的研究历程,将气候适宜度研究划分为3个阶段:研究的起步阶段、初步发展应用阶段及应用研究升温阶段。从气候适宜度模型的改进、气候适宜度应用的延伸及气候适宜度模型的发展3个方面介绍了我国在气候适宜度方面的主要成果和进展;从气候变化对农业的影响角度及气候适宜度研究存在的薄弱环节等方面,提出立足作物生长模型的气候适宜度模型研究、立足特色农业的气候适宜度研究、立足气候变化的气候适宜度研究、立足不同理论的气候适宜度模型研究和气候适宜度评价指标研究等方面将是未来气候适宜度研究的重点和热点。     

Simulating Potential Distribution of Tamarix chinensis in Yellow River Delta by Generalized Additive Models

There are typical ecosystems of littoral wetlands in the Yellow River Delta. In order to study the relationships between Tamarix chinensis and environmental variables and to predict T. chinensis potential distribution in the Yellow River Delta, 641 vegetation samples and 964 soil samples were collected in the area in October of 2004, 2005,2006 and 2007. The contents of soil organic matter, total phosphorus, salt, and soluble potassium were determined.Then, the analyzed data were interpolated into spatial raster data by Kriging interpolation method. Meanwhile, the digital elevation model, soil type map and landform unit map of the Yellow River Delta were also collected. Generalized Additive Models (CAMs) were employed to build species - environment model and then simulate the potential distribution of T. chinensis.The results indicated that the distribution of T. chinensis was mainly limited by soil salt content, total soil phosphorus content, soluble potassium content, soil type, landform unit, and elevation. The distribution probability of T. chinensis was produced with a lookup table generated by Grasp Module (based on GAMs) in software Arc View GIS 3.2. The AUC (Area Under Curve) value of validation and cross - validation of ROC (Receive Operating Characteristic) were both higher than 0.8, which suggested that the established model had a high precision for predicting species distribution.     

On the comparison of tidal gravity parameters with tidal models in central Europe

Two accurately calibrated superconducting gravimeters (SGs) provide high quality tidal gravity records in three central European stations: C025 in Vienna and at Conrad observatory (A) and OSG050 in Pecný (CZ). To correct the tidal gravity factors from ocean loading effects we compared the load vectors from different ocean tides models (OTMs) computed with different software: OLFG/OLMP by the Free Ocean Tides Loading Provider (FLP), ICET and NLOADF. Even with the recent OTMs the mass conservation is critical but the methods used to correct the mass imbalance agree within 0.1 nm/s². Although the different software agrees, FLP probably provides more accurate computations as this software has been optimised. For our final computation we used the mean load vector computed by FLP for 8 OTMs (CSR4, NAO99, GOT00, TPX07, FES04, DTU10, EOT11a and HAMTIDE). The corrected tidal factors of the 3 stations agree better than 0.04% in amplitude and 0.02° in phase. Considering the weighted mean of the three stations we get for O1 δ_c = 1.1535 ± 0.0001, for K1 δ_c = 1.1352 ± 0.0003 and for M2 δ_c = 1.1621 ± 0.0003. These values confirm previous ones obtained with 16 European stations. The theoretical body tides model DDW99/NH provides the best agreement for M2 (1.1620) and MATH01/NH for O1 (1.1540) and K1 (1.1350). The largest discrepancy is for O1 (0.05%). The corrected phase α_c does not differ significantly from zero except for K1 and S2. The calibrations of the two SG's are consistent within 0.025% and agree with Strasbourg results within 0.05%.     

On model validation for meso/submesoscale currents: Metrics and application to ROMS off Central California

ROMS with horizontal grid spacing of 3.5 km for the region off Central California was compared to RAFOS float observations and satellite altimetry on meso/submesoscales. The approach introduced and used two new metrics for model-data comparison, as well as suggested how to calculate these metrics for different spatio-temporal scales. The first metric consisted of the first two moments of exit time and was used to compare ROMS against RAFOS float observations at mid-depths (between 300 m and 350 m). Exit time is the time a float launched at a point takes to leave a domain for the first time. The second metric was spectral entropy and was used to estimate how well ROMS reproduced variability of the sea surface height (SSH) anomaly field extracted from an AVISO data set (1992–2007) for specified temporal and spatial scales. Calculations showed that ROMS reproduced the mid-depth mesoscale/submesoscale currents next to the coast in a very accurate manner (low-order exit time statistics of floats were reproduced by ROMS with an accuracy better than 95%); but ROMS overestimated the speed of westward drift of floats by as much as 20–30% at distances greater than 350 km from the coastline. ROMS predicted the variability of the mesoscale (100–400 km) SSH anomaly field for temporal scales of 1–12 months with a reasonable accuracy. A wavelet transform modulus maxima technique applied to the spectral entropy of SSH anomaly also demonstrated good agreement between ROMS and satellite altimetry for mesoscales characterized by singular exponents and multi-fractal spectra for 1–12 month time scales.     

高分辨率统计降尺度数据集NEX-GDDP对中国极端温度指数模拟能力的评估

利用1986—2005年中国地面气象台站观测的格点化逐日气温资料（CN05.1）评估了高分辨率统计降尺度数据集NASA Earth Exchange/Global Daily Downscaled Projections（NEX-GDDP）中21个全球气候模式对中国极端温度指数的模拟能力。在选用了日最低温度最大值（TNx）、日最高温度最大值（TXx）、暖夜指数（TN90p）和暖昼指数（TX90p）来研究极端温度事件的变化。结果显示:（1）除MRI-CGCM3模拟的日最高温度最大值外,其余模式对4个指数的模拟结果均表现出与观测一致的上升趋势,但模拟结果的平均值相对观测平均低0.26℃/（10 a）（日最低温度最大值）、0.19℃/（10 a）（日最高温度最大值）、2.21%/（10 a）（暖夜指数）、1.04%/（10 a）（暖昼指数）。（2）不同模式对各指数变化趋势空间分布特征的模拟存在较大差别,对日最低温度最大值、日最高温度最大值、暖夜指数和暖昼指数模拟能力最优模式分别为CCSM4、CESM1-BGC、MIROC-ESM-CHEM和bcc-csm1-1。模式模拟的日最低温度最大值和日最高温度最大值气候态平均值与观测值的相关系数在0.97以上。暖夜指数和暖昼指数模拟结果与观测值的标准差比值为0.34—1.58,均方根误差变化为1.6%—3.47%,对这两个指数模拟能力较优的模式分别为MIROC-ESM-CHEM（暖夜指数）和CESM1-BGC（暖昼指数）。（3）综合模式对4个指数在气候态平均值和变化趋势模拟能力的评估结果来看,CanESM2、CESM1-BGC和MIROC-ESM-CHEM显示了相对较高的模拟能力。因此,在利用GDDP-NEX研究未来极端温度事件时,建议将它们作为优选模式。      

微机GIS系统软件设计的原理与方法

本文介绍了北京大学遥感技术应用研究所(国家遥感中心技术培训部)于1988年4月推出的地理信息系统通用软件PURSIS的设计原理与方法。由于它是在IBMPC/XT,AT及系列兼容机上研制的,因此便于推广使用。为了克服微机在速度和容量上的种种限制,PURSIS系统采用了一些较复杂的技术手段,使得与其它系统相比,具有如下明显特点:(1)利用软件技术,为图形的输入和编辑创立了一个良好的交互式工作环境,使用户能方便地输入和修改各种地图。(2)采用压缩编码技术存贮图形和图像数据,从而大大减轻了微机系统的空间负担。(3)设计了高效率的数据格式转换算法,使矢量数据能快速转换为网格数据。(4)设计了COLOR 136软件,将廉价的COLOR-400卡支持的16种颜色扩充为136种颜色,成功地解决了专题图件的显示问题。(5)解决了图形数据和属性数据的联合操作问题,使用户能在图的逻辑概念上进行多种操作。此外,数字地形模型和其它数据在操作时的联系甚为紧密。(6)提供了一些常用的应用工具,如专家权重、叠加分类、专家命题等模型。使用户在这些模型支持下解决一些各自的专业问题。(7)解决了FORTRAN语言、编译DBASE Ⅲ和8086宏汇编语言之间的相互调用问题,使系统设计灵活多变,并能充分利用微机的系统功能。     

Spatial management measures for disease mitigation as practiced in Scottish aquaculture

Aquaculture is an increasingly important economic activity in coastal waters. The fluid environment means spatial management is an important tool for protecting fish health. Scottish aquaculture (largely Atlantic salmon) uses a range of different types of area to group farms for different management or reporting purposes related to fish health. Farm Management Areas are defined by local knowledge and used by industry for co-operation among groups of farms, including in the management of sea lice. Disease Management Areas, defined using a simple but robust model, are used by the Scottish Government for control of notifiable diseases. Particle dispersal models are used to assess areas affected by treatment residue around farms, and to manage maximum allowable area biomass for environmental protection. Sophisticated models of sea lice transport have been developed to help inform management of this key parasite. Large regional areas are used for a variety of purposes, such as a policy presumption against new farms covering the entire east and north coasts of Scotland, and five reporting areas for official production statistics. Scottish aquatic environments are shared by many interest groups and spatial management is proving essential for sustainable development by aquaculture and other users.     

Stochastic Modeling of Short Term Variations of Sea Level in Eastern Canada

Hourly sea level records from three stations in eastern Canada (Québec-Lauzon, Harrington-Harbour and Halifax) are analyzed both in frequency domain from 1970 to 1979 and in time domain during 1973. At the three stations, the deterministic model explains 90 to 96% of the total variability of sea level. The semidiurnal and diurnal tides contribute largely to its variations. The residual series, less than 10% of the initial variations of sea level, contain irregular values including extreme values of seiches and storm surges. Such random variations are analyzed and modeled following the method described by Box and Jenkins (1976). The long period variations (2 to 30 days) can be attributed to meteorological forcing (atmospheric pressure and winds). The short period variations (some hours to one day) can be attributed to longitudinal seiches, semidiurnal and diurnal atmospheric tides, and inertial oscillations. The water discharge from the St. Lawrence River contributes 29% of the monthly residual sea level at Qué     

The Solar Wind at 1 AU During the Declining Phase of Solar Cycle 23: Comparison of 3D Numerical Model Results with Observations

We present results of solar-wind parameters generated by 3D MHD models. The ENLIL inner-heliosphere solar-wind model together with the MAS or Wang – Sheeley – Arge (WSA) coronal models, describe the steady solar-wind stream structure and its origins in the solar corona. The MAS/ENLIL and WSA/ENLIL models have been tuned to provide a simulation of plasma moments as well as interplanetary magnetic-field magnitude and polarity in the absence of disturbances from coronal transients. To investigate how well the models describe the ambient solar wind structure from the Sun out to 1 AU, the model results are compared to solar-wind measurements from the ACE spacecraft. We find that there is an overall agreement between the observations and the model results for the general large-scale solar-wind structures and trends, such as the timing of the high-density structures and the low- and high-speed winds, as well as the magnetic sector structures. The time period of our study is the declining phase of Solar Cycle 23 when the solar activity involves well-defined stream structure, which is ideal for testing a quasi-steady-state solar-wind model.     

On modelling the effects of afforestation on acidification in heterogeneous catchments at different spatial and temporal scales

A modelling approach is presented for simulating and predicting future changes in streamwater Gran alkalinity throughout a large, heterogeneous river system. The methodology is based on integrating End Member Mixing Analysis (EMMA), the Model of Acidification of Groundwater in Catchments (MAGIC) and spatial data describing the catchment characteristics stored on a Geographical Information System (GIS). These are integrated within a Functional Unit Network (FUN) to predict the changes in Gran alkalinity resulting from possible future changes in atmospheric deposition and land use (low intensity afforestation) in the River Dee catchment, NE Scotland. Model results indicate that declining sulphate and constant nitrogen deposition, combined with low intensity Scots pine (Pinus sylvestris) afforestation are unlikely to contribute significantly to streamwater acidification.