梧州地区降水和气温的气候特征

应用梧州地区5个站点1954～2011年逐月降水和平均气温资料,采用趋势分析、小波分析法,分析了近58年梧州地区降水和气温的变化趋势、变化周期性等气候特征。结果表明,近58年梧州地区年降水量、冬季降水量总体呈增加趋势,年降水量存在25年左右、10年左右的震荡周期,季降水量存在一个10年左右的振荡周期最为明显;年平均气温存在一个9～11年的振荡周期;近58年梧州全年、夏季、秋季、冬季平均气温总的趋势均表现为升高趋势,但升高的幅度不同,梧州全年平均气温上升幅度为0.152℃/10a,气候变暖表现明显;梧州58年来出现夏季严重多雨事件8次,严重少雨事件7次;出现秋季严重多雨事件3次,严重少雨事件2次。     

未来中高排放情景下松嫩平原农业气候资源变化分析

基于松嫩平原地区基准时段（1961−1990年）的观测数据,应用统计方法对模型模拟的未来30a(2021−2050年)温度、降水、辐射的逐日数据进行偏差订正,同时采用五日滑动平均法计算≥10℃积温,分析研究区域相对于基准时段,未来30a农业气候资源指标的时空变化特征。结果表明：在RCP4.5和RCP8.5两种排放情景下,未来30a松嫩平原大部分地区平均温度在4～8℃,较基准时段升高2.5～2.8℃,且北部地区的增温幅度大于南部地区;此外,大部分地区≥10℃积温介于3000～3700℃·d,两种情景下分别增加500～550℃·d和600～670℃·d,其中南部部分地区增幅超过670℃·d;大部分地区年降水量在460～580mm,增量为50～90mm不等,降水增量在空间分布上表现为南多北少,其中南部地区增量超过90mm,而北部地区年增量则不足50mm,两种情景在相同区域的降水增量表现为RCP4.5多于RCP8.5;相较于基准时段,年辐射量减少85～100MJ·m−2,生长季内辐射量减少10～40MJ·m−2,变化趋势均不明显。综上所述,未来松嫩平原地区农业气候资源表现为整体提升趋势,农作物可种植期相对延长,因此,应适当种植生育期更长的作物,避免因未来气温升高,造成现有作物生育期缩短,导致产量降低的情况发生;同时研究结果对调整种植结构、改变种植措施和选育作物品种等具有指导意义,有利于充分利用气候资源,提高作物产量。     

黄土高原不同水平年旱涝时空分布特征分析

全球气候变暖大背景下,黄土高原总体呈现暖干化趋势,未来干旱还可能会加剧。为了全面了解黄土高原旱涝时空变化特征,为黄土高原应对旱涝灾害提供决策依据,根据黄土高原及周边263个气象站的降水数据划分降水水平年,以标准化降水指数（SPI）为指标,分析了黄土高原地区不同水平年年际及年内旱涝特征。结果显示,黄土高原在丰、平、枯水年均有不同程度的干旱发生。丰水年黄土高原干旱面积占5.7%,雨涝面积占40.9%;平水年干旱面积占12.7%,雨涝面积占19.3%;枯水年干旱面积占44.4%,雨涝面积占17.9%。不同水平年的干旱区域存在差异。不同水平年内春旱较重,丰水年和平水年雨季开始后干旱逐渐缓解,枯水年雨季不能有效缓解春季以来的干旱,且秋涝明显,各水平年年内干旱的时空分布存在显著差异。不同水平年年际和年内旱涝差异大且变化频繁,为了确保黄土高原农业生产旱涝保收,应合理布设小型水利工程与田间灌溉设施。      

气候变化对海原县主要粮食产量的影响分析

分析了宁夏海原近20年来平均气温、降水量和日照时数等3个主要气候因子的变化趋势及粮食产量的增减趋势,并利用灰色关联度分析法分析了气候因子与粮食产量的关联度、关联系数。结果表明,平均气温对粮食总产量和玉米单产的影响最大,关联度分别为0.7110和0.7006;降水量与小麦单产的关联度最大,为0.7685。     

Fine scale variability in soil extracellular enzyme activity is insensitive to rain events and temperature in a mesic system

While soil extracellular enzyme assays (EEAs) are frequently used to infer soil microbial function, the data typically reflect a small number of sampling points across a season, and it is unclear to what extent soil EEA may vary on the time scale of days to weeks. Rain events, in particular, may cause rapid shifts in EEA, and fine scale temporal data are needed to properly assess the generality of EEA data collected at coarser time scales. We examined soil EEA 2-3 times per week in the field from June to November in the context of natural rain events and temperature fluctuations, and explored how long-term water addition altered EEA responses. We also tested the short-term effects of water addition on the distribution of EEA in intact soil mesocoms and leachate. There was little temporal variation in EEA for the hydrolases phosphatase, N-acetyl-glucosaminidase and β-glucosidase, despite the occurrence of multiple large rain events and large soil temperature fluctuations. Phenol oxidase activity correlated significantly with seasonal trends in temperature and soil moisture, but was highly variable at short time scales, and the latter did not correlate significantly with short-term changes in soil microclimate. EEA generally increased in response to long-term water addition, and in soil mesocosms water addition did not significantly redistribute EEA among the upper and lower soil layers, and leachate EEA was three orders of magnitude lower than soil EEA. Overall, our results reveal relatively minor short-term variation in EEA for hydrolase enzymes, and no discernable response to temperature fluctuations or precipitation over the short term. However, high short-term variation in phenol oxidase activity suggests that it may be difficult to infer temporal trends in EEA for this enzyme from a limited number of sampling points.     

Spatio-temporal variability of precipitation, temperature and agricultural drought indices in Central Italy

The agricultural sector is probably the one that will suffer most directly from the climatic variations expected at the global level. In particular, the analysis of the changes expected in water availability and demand is fundamental in order to correctly establish both the present water resource management and the definition of new strategies. In this paper the time series of some climatic and agro-climatic indices in the Region of Umbria (Central Italy) have been analyzed with the aim of finding signs of climate changes and identifying the potential impacts on the agricultural water balance. The aforesaid indices include the precipitation, the mean maximum and minimum temperatures (Tmin, Tmax), the mean temperature range (ΔT), the reference evapotranspiration (ET0) and two drought indices, Standardized Precipitation Index (SPI) and Standardized Deficit Index (SDI, based on the difference between ET0 and precipitation). These indices were analyzed with reference to different periods (in particular the average growing and irrigation seasons). Furthermore, more specific information was obtained by analyzing the simulated water requirement (CWR) and evapotranspiration deficit (ED) of two typical annual crops (corn and sunflower). The time series of the indices were quantified for 38 stations in the region and they were then analyzed with non-parametric tests both at single sites and at the regional level. The tendencies in cumulated precipitation are generally decreasing (particularly during the wet period) and they are also characterized by a defined spatial pattern. The rainfall reduction during the irrigation season, although less widespread, could have the most important practical consequences. The significant trends detected for both the Tmax and Tmin are mainly positive, and they are more evident for Tmin, often resulting in a reduction of ΔT. ET0 shows a prevailing stationary condition due to the counteracting effects of the prevalent reduction observed for the ΔT and the increment of the mean temperature. At any rate, with reference to the irrigation season, ET0 trends are mainly positive. The results obtained for SPI and SDI are in accordance with the tendencies of non-standardized indices with an expectation of extreme drought event occurrence doubled or even tripled over a 30-year time span. Finally, the analysis of the CWR for corn and the ED for sunflower shows a relevant presence of significant positive trends whose impacts can be estimated in respective mean increments of about 23% and 44% over a 50-year time span.     

基于小波分析的西安降水时间序列的变化特征

应用墨西哥帽小波函数进行小波变换,对西安市45a（1961-2005年）来的降水量数据进行分析,计算小波方差,从而研究西安市降水变化的时间及其周期变化特征。通过对西安市的降水时间序列的小波分析,揭示其在不同层次上的降水结构和异常变化规律以及突变特征,预测了西安市四季降水量以及年降水量的变化趋势。特别是通过小波分析的预测结果在2009和2010年出现的关中地区大面积的春旱以及2005年以后出现的秋涝中得到验证,这对认识西安市降水特征以及对西安地区的农业生产和渭河防迅工作具有重要的参考价值和指导意义。45a来,除西安市春季降水量呈显著下降趋势外（P〈0.05）,其它季节和年降水量的线性变化趋势均不显著。但季节降水量和年降水量都存在多时间尺度特征,不同的时间尺度表现为不同的循环交替,大尺度的周期变化嵌套着小尺度的周期变化。总体上表现为由小尺度的震荡剧烈、没有明显规律到大尺度出现明显规律后继续增强或先升后降。     

宁安市作物生长季气候资源分析

利用宁安站1971-2000年30年的气象资料,主要从热量资源和降水资源两方面分析了宁安市作物生长季的气候资源变化特征,并为宁安市在农业生产中合理有效地利用农业气候资源提供了建议。     

一次人工影响天气作业的增雨效果分析

随着科技水平的提高,人工影响天气作业作为防灾减灾的科学手段,其效果和效益越来越受人们关注。采用高炮或火箭向对流云或层状云中播撒碘化银,对云层中的水滴或冰粒子实施人工干预,进行静力催化和动力催化,促进和加速水滴或冰粒增长并下落,达到人工增雨抗旱的目的,其直接效益已得到一致公认。对2012年3月21日聊城市一次人工增雨抗旱作业的直接增雨效果进行了分析,初步得出在初春层状云中实施人工影响天气作业的效果十分明显。