CMIP5气候模式模拟的北极海冰特征及其季节变化

This paper is focused on the seasonality change of Arctic sea ice extent(SIE) from 1979 to 2100 using newly available simulations from the Coupled Model Intercomparison Project Phase 5(CMIP5).A new approach to compare the simulation metric of Arctic SIE between observation and 31 CMIP5 models was established.The approach is based on four factors including the climatological average,linear trend of SIE,span of melting season and annual range of SIE.It is more objective and can be popularized to other comparison of models.Six good models(GFDL-CM3,CESM1-BGC,MPI-ESM-LR,ACCESS-1.0,Had GEM2-CC,and Had GEM2-AO in turn) are found which meet the criterion closely based on above approach.Based on ensemble mean of the six models,we found that the Arctic sea ice will continue declining in each season and firstly drop below 1 million km~2(defined as the ice-free state) in September 2065 under RCP4.5 scenario and in September 2053 under RCP8.5 scenario.We also study the seasonal cycle of the Arctic SIE and find out the duration of Arctic summer(melting season) will increase by about 100 days under RCP4.5 scenario and about 200 days under RCP8.5 scenario relative to current circumstance by the end of the 21 st century.Asymmetry of the Arctic SIE seasonal cycle with later freezing in fall and early melting in spring,would be more apparent in the future when the Arctic climate approaches to "tipping point",or when the ice-free Arctic Ocean appears.Annual range of SIE(seasonal melting ice extent) will increase almost linearly in the near future 30–40 years before the Arctic appears ice-free ocean,indicating the more ice melting in summer,the more ice freezing in winter,which may cause more extreme weather events in both winter and summer in the future years.     

地电场日变幅与地电暴分析

利用昌黎台地电场资料分析地电场日变幅季节变化特征,显示有季节效应,EW、SN测向夏季日变幅地震最大,而出现最小值的季节两测向表现不一。分析认为,与地电场观测信号的复杂多样性有关。地电暴可以记录到磁暴急始变幅、初相、主相的变化形态,但由于电场和磁场之间存在一阶差分的关系,并不是所有地电暴都和地磁暴变化一致,甚至有些地电暴没有变化形态,而是出现高频上下起伏的脉冲形式。利用多台地电场资料,对同一个K指数为7的磁暴进行急始变幅、扰动最大变幅分析,结果显示,各台不尽相同,可能与台址介质的电性结构有关。     

Start of vegetation growing season on the Tibetan Plateau inferred from multiple methods based on GIMMS and SPOT NDVI data

In this study, we have used four methods to investigate the start of the growing season (SGS) on the Tibetan Plateau (TP) from 1982 to 2012, using Normalized Difference Vegetation Index (NDVI) data obtained from Global Inventory Modeling and Mapping Studies (GIMSS, 1982-2006) and SPOT VEGETATION (SPOT-VGT, 1999-2012). SGS values estimated using the four methods show similar spatial patterns along latitudinal or altitudinal gradients, but with significant variations in the SGS dates. The largest discrepancies are mainly found in the regions with the highest or the lowest vegetation coverage. Between 1982 and 1998, the SGS values derived from the four methods all display an advancing trend, however, according to the more recent SPOT VGT data (1999-2012), there is no continuously advancing trend of SGS on the TP. Analysis of the correlation between the SGS values derived from GIMMS and SPOT between 1999 and 2006 demonstrates consistency in the tendency with regard both to the data sources and to the four analysis methods used. Compared with other methods, the greatest consistency between the in situ data and the SGS values retrieved is obtained with Method 3 (Threshold of NDVI ratio). To avoid error, in a vast region with diverse vegetation types and physical environments, it is critical to know the seasonal change characteristics of the different vegetation types, particularly in areas with sparse grassland or evergreen forest.     

我国西部地区冬季雪盖遥感和变化分析

用改进的甚高分辩率扫描辐射仪(AVHRR)资料,在多光谱判识的基础上提取积雪信息的计算方法,并由此得到积雪遥感动态监测结果;同时,利用我国短时间序列的积雪资料,统计计算了新疆、内蒙古、青海、西藏和东北地区冬季积雪覆盖率,分析了我国西部地区积雪覆盖特征和变化规律;补充了常规气象台站对我国西部地区积雪监测和分析的不足.     

义乌市降水变化特征分析

根据历史和实测资料的统计分析,得到义乌市的降水变化特征。结果表明:丰水期义乌市的涝年偏多,旱年偏少,而枯水期则旱年偏多,涝年偏少。厄尔尼诺事件的当年或翌年,义乌市的降水显著偏多,而拉尼娜事件的当年或翌年,义乌市的降水则显著偏少。丰水期平均入梅日偏早,平均出梅日偏晚,平均梅雨日数偏长,平均梅雨量偏多,而在枯水期则反之。义乌市6月6—15日入梅的可能性最大,出梅日期的时间分布相对比较分散,其集中期的发生规律不如入梅集中期明显。厄尔尼诺事件的当年或翌年,义乌市的出梅日偏晚,而拉尼娜事件的当年或翌年,义乌市的出梅日偏早。研究结果可为水库源区雨季的人工增雨作业提供科学依据。     

Characteristics of climate change in the “significant impact zone” affected by aerosols over eastern China in warm seasons

Through analysis of the distribution pattern and changing characteristics of atmospheric aerosols over the East Asia region during warm seasons in recent 20 a and beyond as well as their possible interactive relationship with a variety of meteorological elements, it is found that the high-value zone of aerosol optical depth derived from the Total Ozone Mapping Spectrometer (TOMS), its significant negative correlation zones in terms of sunshine duration (SD) and surface air temperature (SAT) and its significant positive correlation zones with low-level cloud amount (LCC) are co-located in the South China region during warm periods. Based on this finding, the region is referred to as a “significant impact zone” (SI zone) affected by aerosols. Then, a comparative analysis is made on variation differences of observed SAT, SD and LCC, etc. in different regions. It is also found that the LCC is increased and the SD is decreased within the “SI zone” over eastern China during the warm season. These characteristics are more evident than those beyond the zone, while the warming trend within the zone is evidently weaker than that outside it. Studies show that since recent 20 a, under the influence of aerosols, the LCC tend to increase substantially with a clear decrease of SD and an unnoticeable warming trend within the “SI zone”. Comparing with the climate change beyond the zone, the difference is significant. Therefore, the effects of atmospheric aerosols on climate is possibly one of the contributions to the difference of climate change existed between the southern and northern parts of the Eastern China during a warm season. Supported by the International Sci-Tech Cooperative Project under the auspices of the Ministry of Science and Technology of the People’s Republic of China (No. 2004DFA06100)     

近35 年青藏高原雨量和雨日的变化特征

利用青藏高原1971-2005 年49 个气象台站逐日雨量和雨日资料, 分析了青藏高原年、 季雨量和雨日变化趋势。结果表明, 近35 年西藏大部分地区年雨量、雨日呈现显著增加趋 势, 而青海省大部分地区雨量、雨日却呈减少趋势。夏半年, 高原上雨日减少, 雨量增加, 说明降水越来越集中, 降水强度在增加。冬半年, 高原上雨日、雨量均在增加。高原夏半年小雨(0.1~4.9 mm) 雨日减少, 雨量增加; 小雨(5.0~9.9 mm) 和中雨的雨日和雨量均呈增加趋 势, 大雨以上的雨日和雨量均减少。冬半年, 青藏高原小雪、中雪、大雪不同量级日数和雪 日的平均雪量均呈增加趋势; 暴雪日和雪量变化均不明显。     

迟熟中粳武育粳3号温光模式的建立与分析

本文通过武育粳3号的播期试验研究,利用生育期的试验资料,结合本地的温光资源,建立其温光模式,从中分析该品种有感温性强,感光性弱的特性,在本地区应采用稀播长秧龄等配套措施,确保在安全齐穗期内齐穗,达到高产的目的。     

Linear regression relationships between NDVI, vegetation and rainfall in Etosha National Park, Namibia

Estimations of 10-day interval green vegetation cover and biomass, 10-day interval cumulative rainfall, as well as annual rainfall are compared with 10-day interval and rainy season NDVI and MVC using linear regression analysis. Raw data were smoothed by averaging and removing dry season outliers. Results indicate that the ability of NDVI and MVC to predict green vegetation cover, cumulative rainfall and annual rainfall is poorer for raw data than for averaged, outlier-removed data. It is recommended that the standard error of the raw data predictions are used to indicate the fundamental error in these relationships, and that the equations of the averaged, outlier-removed data are used to indicate the fundamental strength of NDVI or MVC in predicting vegetation or rainfall. The practical use of integrated rainy season MVC images are discussed.     

滇池流域入湖河流丰水期着生藻类群落特征及其与水环境因子的关系

着生藻类是重要的水环境指示生物,其物种组成、生物密度以及多样性指数等群落特征被广泛用于监测和评价人为活动干扰对水生生态系统所造成的影响.本文根据滇池流域29条入湖河流2009年7-8月着生藻类调查数据,以及2008年9月至2009年8月逐月水环境指标监测数据,通过运用等级聚类分析、因子分析和典型对应分析,来探讨滇池流域...