Spatially explicit modelling of the impact of climate changes on pasture production in the North Island,New Zealand

To assess the potential impact of climate changes on pasture production in the North Island, New Zealand, eight climate scenarios of increased temperature and increased (or decreased) rainfall were investigated by integrating a polynomial regression model for pasture production with a Geographic Information System (GIS). The results indicated that the climate change scenarios assuming an increase in temperature by 1–2°C and a rainfall change by −20 to +20% would have a very significant impact on pasture production with a predicted pasture production variation from −46.2 to +51.9% compared with the normal climate from 1961–1990. Increased temperature would generally have a positive effect on pasture production in the south and southeast of the North Island, and increased rainfall would have a positive effect in the central, south and southeast of the North Island and a negative effect in the north of the North Island. The interaction of decreased rainfall and increased temperature would have a negative impact for the whole North Island except some central areas with high rainfall. Relevant management practices for coping with potential climate change are discussed.     

河套地区一次寒潮天气的环流形势分析

利用常规气象观测资料和Micaps提供的相关资料,对2009年9月19—20日在河套地区发生的寒潮天气的环流形势及物理量进行分析。分析表明:在寒潮爆发前期,500hPa系统,蒙古西部的冷中心强度≥-32℃,且温度场滞后于高度场,为冷空气爆发南下提供了最基本条件;700hPa河套地区及上游≥16m.s-1的西北风急流基本形成,等温线与等高线交角≥45°且10个纬距内有4条及以上等温线的密集区;850hPa河套地区有≥16℃的暖中心,高空槽前后的西北风速≥18 m.s-1,温度线与高度线的夹角>45°;地面蒙古气旋的暖性性质为寒潮爆发的前期提供了有利的热力条件,地面冷锋后部冷高压轴线接近南北向,且冷高压中心强度≥1040hPa,3h变压≥3hPa。     

辽宁省耕地植被指数变化特征分析

利用NOAA/AVHRR资料通道1(0.58~0.68μm)、通道2(0.725~1.1μm)数据计算归一化植被指数(NDVI),对辽宁省5个气候区内1999~2004年208个旱田监测点和84个水田监测点的作物生长状况进行连续监测,分析NDVI年际、旬际变化特征。结果表明:辽宁耕地(旱田、水田)植被指数年际间差异明显,造成旱田年际变化以及地区差异的主要原因是降水时空分布不均匀的结果,因此旱田2004年NDVI达到近年最大,2001年较低;而造成水田年际差异以及地区差异的原因是受水田用水状况以及光温条件的影响,水田2003年NDVI最大,2001年较低。在整个生长季内(5~9月份),辽宁耕地植被指数呈单峰型变化,从5月上旬开始到6月中旬是缓慢增长阶段,6月下旬到8月下旬快速增长并达到最大,之后又迅速降低;2004年耕地植被指数旬变化趋势与6 a平均植被指数旬变化趋势基本相同,但作物生长前期NDVI较6 a平均值低,主要原因是受到2004年春夏之交严重干旱的影响。     

基于通量距平的大气-海洋-海冰耦合模式

该文是对基于月平均通量距平（ＭＦＡ）的海气耦合方案及其在４个海气耦合的环流模式中应用情况的一个综合评述．这些模式的实施情况表明，由于采用精细化了的参考通量，修正的ＭＦＡ（ＭＭＦＡ）比它的原型具有更为稳定的控制气候漂移的能力．     

上海城市二氧化碳排放空间特征

构建上海1 km CO₂排放网格,分析市域（UB1）、市辖区（UB2）、建成区（UB3）和城区（UB4）4个城市范围的CO₂排放特征。上海市域CO2排放空间格局是以中心城区为核心,排放水平向外递减,形成了3个梯度。空间自相关分析表明,排放在空间上存在显著的集聚效应,部分地区高强度的经济活动和能源活动对周边区域的排放有显著影响。UB4是上海城市的最佳表征,2007年UB4内CO₂排放达到1.89亿t,人均排放12.04 t;UB4排放占UB1排放的75.40%,UB1人均排放比UB4人均排放高12%。上海城市化和工业化在空间上的高度重合,导致高排放源集聚于UB4内,形成UB4的高排放特征。个别网格的排放量已经占到区域或者城市总排放量的10%～20%;前10高和前100高排放网格,其累积排放总量分别占据了3个城市范围（UB1、UB3和UB4）总排放量的60%和80%以上。     

Influences of climate change on California and Nevada regions revealed by a high-resolution dynamical downscaling study

In this study, the influence of climate change to California and Nevada regions was investigated through high-resolution (4-km grid spacing) dynamical downscaling using the WRF (Weather Research & Forecasting) model. The dynamical downscaling was performed to both the GFS (Global forecast model) reanalysis (called GFS-WRF runs) from 2000?C2006 and PCM (Parallel Climate Model) simulations (called PCM-WRF runs) from 1997?C2006 and 2047?C2056. The downscaling results were first validated by comparing current model outputs with the observational analysis PRISM (Parameter-elevation Regressions on Independent Slopes Model) dataset. In general, the dominant features from GFS-WRF runs and PCM-WRF runs were consistent with each other, as well as with PRISM results. The influences of climate change on the California and Nevada regions can be inferred from the model future runs. The averaged temperature showed a positive trend in the future, as in other studies. The temperature increases by around 1?C2°C under the assumption of business as usual over 50?years. This leads to an upward shifting of the freezing level (the contour line of 0°C temperature) and more rain instead of snow in winter (December, January, and February). More hot days (>32.2°C or 90°F) and extreme hot days (>37.8°C or 100°F) are predicted in the Sacramento Valley and the southern parts of California and Nevada during summer (June, July, and August). More precipitation is predicted in northern California but not in southern California. Rainfall frequency slightly increases in the coast regions, but not in the inland area. No obvious trend of the surface wind was indicated. The probability distribution functions (PDF) of daily temperature, wind and precipitation for California and Nevada showed no significant change in shape in either winter or summer. The spatial distributions of precipitation frequency from GFS-WRF and PCM-WRF were highly correlated (r?=?0.83). However, overall positive shifts were seen in the temperature field; increases of 2°C for California and 3°C for Nevada in summer and 2.5°C for California and 1.5°C for Nevada in winter. The PDFs predicted higher precipitation in winter and lower precipitation in the summer for both California and Nevada.     

DLP大屏幕投影墙显示系统在山西气象业务工作中的应用

DLP（Digital Light Processor）大屏幕投影墙显示系统是集多种信息接收处理显示、多功能平台综合鼹示与控制于一体的全数字多用途高科技显示系统,在气象部门天气预报会商和会议系统中已普遍使用？奉文拟对DLP的技术特点和优势进行分析,结合山西省气象台业务现状和发展需求,对DLP大屏幕显示系统在业务一体化会商室业务平台中的设计方案及应用情况进行探讨,对应用DLP大屏幕显示系统后的远景功用和效益进行分析,旨在为气象DLP大屏幕项目建设提供前期研究支持。     

气象电视会商会议系统的使用和维护

本文介绍省台———国家气象中心的电视会议系统的构成原理,总结省台与国家气象中心电视会商系统使用维护过程中的经验,对系统的使用和正在进行安装调试的“省—市—县”电视会商系统的使用提供借鉴。     

Comparison of different order Adams-Bashforth methods in an atmospheric general circulation model

The Asselin-Robert time filter used in the leapfrog scheme does degrade the accuracy of calculations. As an attractive alternative to leapfrog time differencing, the second-order Adams-Bashforth method is not subject to time splitting instability and keeps excellent calculation accuracy. A second-order Adams-Bashforth model has been developed, which represents better stability, excellent convergence and improved simulation of prognostic variables. Based on these results, the higher-order Adams-Bashforth methods are developed on the basis of NCAR (National Center for Atmospheric Research) CAM 3.1 (Community Atmosphere Model 3.1) and the characteristics of dynamical cores are analyzed in this paper. By using Lorenz nonlinear convective equations, the filtered leapfrog scheme shows an excellent pattern for eliminating 2Δt wave solutions after 20 steps but represents less computational solution accuracy. The fourth-order Adams-Bashforth method is closely converged to the exact solution and provides a reference against which other methods may be compared. Thus, the Adams-Bashforth methods produce more accurate and convergent solution with differencing order increasing. The Held-Suarez idealized test is carried out to demonstrate that all methods have similar climate states to the results of many other global models for long-term integration. Besides, higher-order methods perform better in mass conservation and exhibit improvement in simulating tropospheric westerly jets, which is likely equivalent to the advantages of increasing horizontal resolutions. Based on the idealized baroclinic wave test, a better capability of the higher-order method in maintaining simulation stability is convinced. Furthermore, after the baroclinic wave is triggered through overlaying the steady-state initial conditions with the zonal perturbation, the higher-order method has a better ability in the simulation of baroclinic wave perturbation.