近期气候波动与LUCC过程对东北农田生产潜力的影响

利用1991~2000年逐日气象资料以及20世纪80年代末和90年代末土地利用数据,估算了东北地区气候波动和LUCC过程对农田生产潜力的影响。结果显示:90年代东北地区由于作物生长季内气候变暖和降水减少,生产潜力普遍降低6.45%,其中降水量变化的区域差异是导致生产潜力变化区域分异的主要原因。在LUCC过程的影响下,东北地区生产潜力总量净增加2 402.79×10⁴t。从气候波动和LUCC过程对生产潜力的影响程度看,气候波动要低于LUCC过程的作用,LUCC过程所导致的生产潜力的增长趋势抵消了气候波动所带来的降低趋势,10年间东北地区农田生产潜力总量净增加992.23×10⁴t。     

1971-2000年青藏高原气候变化趋势

Trends of annual and monthly temperature, precipitation, potential evapotranspi- ration and aridity index were analyzed to understand climate change during the period 1971–2000 over the Tibetan Plateau which is one of the most special regions sensitive to global climate change. FAO56–Penmen–Monteith model was modified to calculate potential evapotranspiration which integrated many climatic elements including maximum and mini- mum temperatures, solar radiation, relative humidity and wind speed. Results indicate gen- erally warming trends of the annual averaged and monthly temperatures, increasing trends of precipitation except in April and September, decreasing trends of annual and monthly poten- tial evapotranspiration, and increasing aridity index except in September. It is not the isolated climatic elements that are important to moisture conditions, but their integrated and simulta- neous effect. Moreover, potential evapotranspiration often changes the effect of precipitation on moisture conditions. The climate trends suggest an important warm and humid tendency averaged over the southern plateau in annual period and in August. Moisture conditions would probably get drier at large area in the headwater region of the three rivers in annual average and months from April to November, and the northeast of the plateau from July to September. Complicated climatic trends over the Tibetan Plateau reveal that climatic factors have nonlinear relationships, and resulte in much uncertainty together with the scarcity of observation data. The results would enhance our understanding of the potential impact of climate change on environment in the Tibetan Plateau. Further research of the sensitivity and attribution of climate change to moisture conditions on the plateau is necessary.     

青岛近海夏季海风特征及其预报方法研究

采用2003～2006年7～9月青岛以及沿海地区自动站资料、探空资料对青岛近海海风进行了统计分析.平均而言,青岛近海7～8月海风发生频率为30%～35%,9月海风发生频率为25%;海风开始时间平均为10:00～12:00,结束时间可以持续到18:00～19:00;海风在垂直方向上厚度为500～600 m左右.青岛近海海风的发生与否取决于青岛上空低层925 hPa风速大小、低层大气稳定度、海陆温差以及海平面气压差四方面的综合效应.通常,925 hPa风速达到8 m/s,系统风较强时不利于海风建立;当低层大气不稳定时,有利于触发海风环流的建立;海陆温差达到4 ℃以上时,青岛近海易出现海风;此外,当地转风为离岸风时,海阳站或日照站与青岛本站08:00时海平面气压差>1 hPa时,当日一般不会出现海风.综合以上预报因子及其指标,通过建立逻辑回归模型,初步实现了夏季青岛近海海风能否发生的客观预报,并在2007年举行的国际帆船赛期间得到了应用.     

Characteristics of extreme temperature event and its response to regional warming in Northwest China in past 45 years

Using the daily maximum and minimum temperature dataset from 128 stations from 1960 to 2004 in Northwest China, daily extreme high temperature （EHT） and extreme low temperature （ELT） thresholds were determined by centesimal method for different stations at first, then yearly EHT and ELT events were counted up in different stations, and the characteristics of their spatio-temporal distribution were diagnosed at last. The study drew following conclusions： 1） The consistent anomaly distribution characteristic was the most important mode of the EHT and ELT events in Northwest China. 2） The spatial distribution of the EHT and ELT events can be divided into five sub-regions, namely, the north of Qinghai and west of Gansu, the north of Xinjiang, the south of Xinjiang, the east of Northwest China and the south of Qinghai. 3） The EHT events showed remarkable increasing trend in all of five sub-regions, but only in the north of Qinghai and west of Gansu area, sudden change phenomenon occurred; the ELT events showed decreasing trend in all of five sub-regions, and sudden change phenomenon occurred in Northwest China except for south of Qinghai. 4） In all of five sub-regions the EHT events showed remarkable 12-14yr period oscillation, and the ELT event showed significant 13-15yr and 7-8yr period oscillation. 5） The EHT and ELT events displayed remarkable positive and negative responses to regional warming of Northwest China respectively.     

Impacts of climate change on commercial fish stocks in Norwegian waters

The Norwegian fishing areas extend over various marine ecosystems that will respond differently to climate change. In the North Sea the productivity of the boreal fish species are likely to decrease under global warming and new warm-water species are expected to become more abundant. In the arctic marine ecosystem of the Barents Sea the fish productivity is expected to increase and their distributions expand northward and eastward under global warming increasing the importance of the Russian as well as the Norwegian sectors of the Barents. In the past, decadal-scale climate variations have been shown to strongly influence productivity and distributions of fish stocks. The importance of such shorter-term variations are expected to continue also under global warming. Under global warming the optimum temperature for fish farming along the Norwegian coast will be displaced northwards from the northern part of West Norway towards the Helgeland coast.     

CCSM3对太平洋年代际振荡的敏感性试验

利用NCAR的CCSM3模式进行控制试验和1870-1999年的130 a模拟试验(敏感性试验),与相应的再分析资料进行对比,分析了太平洋海区的海温变化趋势和北太平洋年代际变率的时空结构,并且讨论了CO2对于北太平洋年代际变率的影响.结果表明:CCSM3模式能够模拟出北太平洋年代际变率的主要特征,其空间分布类似于典型的...     

黄海西部2005—2007年海雾演变的气候特征研究

海雾对沿海地区的交通运输、工农业生产等影响很大,需要开展深入研究,以探索其生消演变规律。本文选择黄海西部的成山头、青岛、海阳、日照等4个测站为代表性测站,分析了2005—2007年海雾发生期间的位势高度、海温、海表面风场、相对湿度、稳定度及散度等要素场特征,着重探讨了海雾演变的气候特征。研究结果表明:500 hPa高空槽前位于黄海上空时有利于成雾;海温异常低的年份雾日较多;风向、散度和低层的层结稳定度是影响黄海海雾的主要因素;地理位置也是影响黄海海雾变化的重要因子;黄海海雾的水平分布具有南北空间不一致的特点。     

热带太平洋气候变率的三类模态及与ENSO强度变化的关系

基于Kaplan等重建的1856—2001年全球海表水温距平(SSTA)资料，用小波变换分析了热带太平洋SSTA的气候变率，对热带太平洋SSTA分别进行2—8、8—30和30—100a带通滤波，然后进行EOF分解。结果发现，ENSO模态具有5a左右的年际变化和15a左右的年代际变化2种显著周期，当二者位相相同时，ENSO事件加强，当二者位相相反时，ENSO事件减弱，当年际变化不明显时，显著的年代际变化也可单独导致ENSO事件；热带太平洋SSTA气候态变率以西太平洋暖池和赤道两侧的热带中东太平洋明显海温同号异常为主要特征，具60a左右的周期，其相位变化与气候跃变及El Nifio事件的类型有密切联系；长期增温倾向加大了El Nifio事件的振幅。文章最后指出，ENSO事件强度变化是由年际、年代际和气候态等3类模态变率共同作用的结果，在ENSO预报模式中考虑并引入年代际和气候态变化对ENSO循环的影响，是提高ENSO预测水平的有效途径之一。     

1997∽1998年厄尔尼诺事件的特征、成因及对气候的影响

1997年爆发了20世纪以来最强的一次厄尔尼诺事件。此次ElNin～o事件的发生,与赤道中、西太平洋地区大气季节内振荡(ISO)在1996年冬到1997年春的异常增强有重要关系。西太平洋暖池次表层海温(SOT)正距平沿温跃层东传到赤道东太平洋并向海洋表层扩展是ElNin～o事件爆发的直接原因。1997～1998年的ElNin～o事件爆发后,引起全球大气环流和世界许多地区的气候异常,导致一些国家和地区多雨洪涝,另外一些国家和地区高温少雨和严重干旱。     

黄、渤海海冰长期变化特征分析

选取渤海、黄海北部冰情等级、冰面积资料和大气环流逐月资料,采用小波分析和交叉小波分析方法,研究海冰长期变化特征及其气候成因。结果发现黄、渤海海冰具有多尺度变化特征,存在低频变化、高频变化和无明显周期的演变过程。西太平洋副高、亚洲极涡以及纬向环流是影响海冰生成与变化的直接因素。黄、渤海海冰还与印度洋副高、北美副高,以及大西洋副高存在显著年代际相关关系。