广州市城市电力消费对气候变化的响应

低纬度地区的城市电力消费对气候变化有较为敏感的响应。该文引入了气候变化对农业产量和能源影响的研究方法, 分别建立了气候变化对电力消费影响强度的动态评估模型和降温度日模型, 对广州市城市电力消费对气候变化的响应作了深入分析。结果表明:广州市城市电力消费量主要受到气温、湿度、风速等气象因子的影响, 其中气温为关键性因子; 综合考虑各气候因子和气候变化的稳定性, 1956—2005年的近50年, 广州市气候变化对城市电力消费影响强度是持续稳定增加的, 正强度出现的概率呈现出增大趋势, 以10%/10a的速度增长; 通过对广州市降温度日的分析可知, 5—10月为主要的降温时期, 其气温的升高对降温度日强度变化影响很大, 达到46.6%/ ℃, 同时, 广州市的降温期长度变率也呈递增趋势, 因此, 气温的升高引发的降温度日的增加对广州市城市电力消费有深刻影响; 在未来气候变暖情景下, 夏季平均最高气温每升高1 ℃, 广州市全年单位工业产值耗电将增加2.02%, 5—10月的平均气温每升高1 ℃, 居民生活用电量的百分比将增加1.25%。在未来, 气候变暖将使城市用电压力有继续增大的趋势。     

Regional climate model projections for the State of Washington

Global climate models do not have sufficient spatial resolution to represent the atmospheric and land surface processes that determine the unique regional climate of the State of Washington. Regional climate models explicitly simulate the interactions between the large-scale weather patterns simulated by a global model and the local terrain. We have performed two 100-year regional climate simulations using the Weather Research and Forecasting (WRF) model developed at the National Center for Atmospheric Research (NCAR). One simulation is forced by the NCAR Community Climate System Model version 3 (CCSM3) and the second is forced by a simulation of the Max Plank Institute, Hamburg, global model (ECHAM5). The mesoscale simulations produce regional changes in snow cover, cloudiness, and circulation patterns associated with interactions between the large-scale climate change and the regional topography and land-water contrasts. These changes substantially alter the temperature and precipitation trends over the region relative to the global model result or statistical downscaling. To illustrate this effect, we analyze the changes from the current climate (1970–1999) to the mid twenty-first century (2030–2059). Changes in seasonal-mean temperature, precipitation, and snowpack are presented. Several climatological indices of extreme daily weather are also presented: precipitation intensity, fraction of precipitation occurring in extreme daily events, heat wave frequency, growing season length, and frequency of warm nights. Despite somewhat different changes in seasonal precipitation and temperature from the two regional simulations, consistent results for changes in snowpack and extreme precipitation are found in both simulations.     

半干旱区不同类型土地利用的蒸散量及水分收支差异分析——以通榆为例

利用吉林通榆半干旱区农田站和退化草地站2008年的外场试验观测资料,对比分析了不同土地利用方式对蒸散和地表水分收支的影响。结果表明：从全年来看,尽管两个站点相距仅5 km,但农田站的全年总蒸散量比代表自然土地覆盖状况的退化草地站高28.2 mm;且生长季两种下垫面的蒸散量较为接近,差异主要发生在非生长季。同时,农田站的年水分收支总量为51.1 mm,比退化草地站低35.6％。具体来说,生长季,两个站点的水分收支均有盈余;但在非生长季,退化草地站的水分收支仍有盈余,而农田站则处于水分亏损状态。这说明在半干旱区,代表人为土地利用状况的农田站面临着更大的水分供给压力,人类活动导致的土地利用会加剧该地区的干旱化趋势。
　　进一步的分析表明,水分盈余并不代表地表的水分状况良好。从 Priestley-Taylor 系数来看,两个站点的Priestley-Taylor系数均远小于1.0,说明在半干旱区,由于表层土壤水分条件的限制,实际蒸散量远未达到平衡蒸散量,土壤面临着水分供给的压力。其可能的原因是,对半干旱区而言,尽管水分收支有盈余,但是由于土壤沙化严重,土壤孔隙度大,大气降水很容易下渗,并以地下水的形式存储起来,使得表层土壤水分供应反而不足。     

Quantifying Arctic contributions to climate predictability in a regional coupled ocean-ice-atmosphere model

The relative importance of regional processes inside the Arctic climate system and the large scale atmospheric circulation for Arctic interannual climate variability has been estimated with the help of a regional Arctic coupled ocean-ice-atmosphere model. The study focuses on sea ice and surface climate during the 1980s and 1990s. Simulations agree reasonably well with observations. Correlations between the winter North Atlantic Oscillation index and the summer Arctic sea ice thickness and summer sea ice extent are found. Spread of sea ice extent within an ensemble of model runs can be associated with a surface pressure gradient between the Nordic Seas and the Kara Sea. Trends in the sea ice thickness field are widely significant and can formally be attributed to large scale forcing outside the Arctic model domain. Concerning predictability, results indicate that the variability generated by the external forcing is more important in most regions than the internally generated variability. However, both are in the same order of magnitude. Local areas such as the Northern Greenland coast together with Fram Straits and parts of the Greenland Sea show a strong importance of internally generated variability, which is associated with wind direction variability due to interaction with atmospheric dynamics on the Greenland ice sheet. High predictability of sea ice extent is supported by north-easterly winds from the Arctic Ocean to Scandinavia.     

影响预报员应用先进天气预报技术的因素分析

先进的天气预报技术只有被预报员有效应用才能发挥其重要作用。为了促进预报员应用先进技术,有必要对影响预报员应用先进技术的各方面因素进行分析研究并提出对策,以提升气象服务能力和提高气象服务质量。本研究对短时临近预报新技术产品从无到有、预报员对新技术产品从陌生到接纳应用的整个过程进行连续3年的互动式调查评估,以B08FDP技术产品被预报员在北京2008年奥运气象服务中的应用过程为例,采用问卷调查和深度访谈的方式,通过2006年预报员的需求调查,挖掘出先进的预报技术产品要被预报员接纳和应用所面临的3个突出问题,并进行分析研究提出对策建议反馈给气象部门;通过2007和2008年追踪分析B08FDP被预报员逐步接受并应用的情况,揭示出要提高预报员对先进技术的应用,就要深入调查预报员需求并给予满足、有针对性地开展预报员培训教育、建立完善预报员与科研人员互动反馈的常态机制。     

祁连山区冬半年积雪分布及变化的遥感研究

利用国家卫星中心提供的1996—2002年冬半年(11月～翌年4月)的旬积雪数据、地面气象站温度和实测积雪数据,以及结合祁连山区DEM数据,研究了同期祁连山区积雪时空分布及其变化特征。结果表明:祁连山区冬半年积雪大多随山脉走向呈带状分布在山脊区,而山谷和南面盆地分布较少;积雪西段最多,东段次之,中段最少。祁连山区不同积雪频率所分布的平均高度的基本趋势为积雪频率越大分布的高度也越高。就不同频率的积雪而言,频率越低所占比例越大,频率越高所占比例越小;总体上祁连山区在1998/1999年冬季积雪达到最小值,在1998/1999年冬季之前呈波动变化,之后呈持续显著增加的趋势,但主要贡献在低频率。对祁连山东、中、西三段而言,东、中两段在1998/1999年冬季前呈减少趋势,1998/1999年冬季后呈增加趋势,东、中两段平均积雪频率变化量很接近;而西段从1996/1997年冬季开始呈缓慢增加的趋势,而且积雪平均出现频率明显要比东、中两段高很多。祁连山东、中、西三段积雪覆盖度随着高度增加而增大,只有中段在1999—2001年随着高度的递增积雪覆盖度增加不明显,变化趋势比较复杂,这可能与中段所受天气系统和地形等的影响比较复杂有关。     

一次冷锋过境后的海风三维结构数值模拟

为研究大尺度系统风对海风的影响以及海风三维结构特征,利用山东省123个地面自动站资料、青岛地区三十多个内陆及沿海、海岛观测站以及奥帆赛场3个浮标站资料,对2006年8月21日青岛一次海风个例进行了分析,并利用美国俄克拉荷马大学风暴分析预测中心开发的ARPS(the Advanced Regional Prediction System)模式,对海风过程进行了数值模拟研究。结果发现:在较强的离岸风背景下,当内陆气温高于海面气温2℃左右时,海风也可以发生。海风首先在海岸线附近的海上开始,发展的同时向内陆及远海地区推进。海风低层环流很浅,主要位于500 m以下。在较强的偏北离岸风下,海风向内陆推进的距离很短。偏北的大尺度系统风由于渤海冷下垫面的影响,不利于青岛海风的维持。海风开始时,在1500～2500 m高度处同时有反环流出现,但直到傍晚前后,海风的垂直环流圈才发展得比较清晰,其高度也更接近地面。海风消亡后,高层的垂直环流圈及反环流维持3 h左右才逐渐消亡。     

Trends in graded precipitation in China from 1961 to 2000

Daily precipitation rates observed at 576 stations in China from 1961 to 2000 were classified into six grades of intensity, including trace （no amount）, slight （≤ 1 mm d^-1）, small, large, heavy, and very heavy. The last four grades together constitute the so called effective precipitation （〉 1 mm d^-1）. The spatial distribution and temporal trend of the graded precipitation days are examined. A decreasing trend in trace precipitation days is observed for the whole of China, except at several sites in the south of the middle section of the Yangtze River, while a decreasing trend in slight precipitation days only appears in eastern China. The decreasing trend and interannual variability of trace precipitation days is consistent with the warming trend and corresponding temperature variability in China for the same period, indicating a possible role played by increased surface air temperature in cloud formation processes. For the effective precipitation days, a decreasing trend is observed along the Yellow River valley and for the middle reaches of the Yangtze River and Southwest China, while an increasing trend is found for Xinjiang, the eastern Tibetan Plateau, Northeast China and Southeast China. The decreasing trend of effective precipitation days for the middle- lower Yellow River valley and the increasing trend for the lower Yangtze River valley are most likely linked to anomalous monsoon circulation in East China. The most important contributor to the trend in effective precipitation depends upon the region concerned.     

The Influences of NAO and the Hudson Bay sea-ice on the climate of eastern Canada

Sea-ice cover over the Hudson Bay (HB) exhibits large variability in the freeze-up season normally starting in November. Its influence on the climate over eastern Canada has been studied with the Canadian Regional Climate Model (CRCM) in three steps. First, a 30-year continuous simulation from 1970 to 1999 was performed as a control run to evaluate the simulated climate variability over eastern Canada, in particularly variability associated with the North Atlantic oscillation (NAO). Then, 50 additional 1 month experiments were performed with modified sea-surface conditions prescribed over the HB. These integrations allowed us to quantify the contribution of HB sea-ice anomalies versus large scale NAO atmospheric variability (as defined by prescribed lateral boundary conditions) in inducing climate variability over eastern Canada. Results show that the NAO is the dominant factor controlling climate variability over eastern Canada. The contribution of HB sea-ice anomalies is significant only in the immediate coastal region. Under the influence of different phases of NAO, HB sea-ice anomalies do co-vary with temperature and precipitation anomalies downstream of the HB over eastern Canada. The ultimate cause of this co-variability is NAO variability which forces variability in both HB sea-ice cover as well as temperature/precipitation over eastern Canada.     

综合气象因素对广西电力负荷的影响

针对电网负荷易受多种气象因素影响的特点,为综合衡量气象因素对广西电力负荷的影响,引入了气象学指数--有效温度,分析了4-10月气温、相对湿度、风及有效气温对电力负荷的影响.结果表明:气温与电力负荷呈显著的正相关关系,气温是影响电力负荷的主要因子;夏季以气温和风速、气温和相对湿度组合的变化对负荷的影响较大,风速从静风到有风时,负荷明显地减少,但当超过一定的温度时,风速越大负荷反而增加;6-9月,负荷随着气温和有效温度的升高呈线性增加;在春夏、夏秋季过渡季节,负荷并不完全随着气温的升高而增加,在气温不是太高的阶段,相对湿度增大时,负荷有下降的趋势,当超过一定的温度时,负荷随气温和有效温度的升高而增加.