1959—2020年江西省持续区域性高温过程特征

利用江西省81个国家气象站气温观测资料,综合考虑高温过程的强度、发生面积和持续时间等要素,运用江西省持续区域性高温过程的判别方法和指标,分析1959—2020年江西省持续区域性高温过程的时空分布及变化特征。结果表明:江西省共发生持续区域性高温过程271次,最强高温过程出现在2003年7月8日—8月10日,累计影响范围4.79×10^(6) km^(2),高温综合指数达到4.27。江西省持续区域性高温过程发生强度和频次较多的区域主要位于东北部和中部;历年发生频率最高为8次/a,其整体呈增加趋势。江西省持续区域性高温过程的年最强过程指数呈“先减小后增大”趋势,1993年以来其强度明显增加。     

江西省夏季干旱特征分析

根据1951～2000年江西省降雨量、降雨日数、降雨变率等资料,统计和分析江西省夏季干旱期间降雨量、降雨日数、降雨变率等变化与地理分布客观特征.文章还对江西干旱标准、干旱指数与伏、秋干旱时空分布客观特征等进行分析.分析结果为江西人工增雨抗旱作业提供依据.     

江西干旱期间人工增雨天气条件与潜力区分析

通过对江西干旱期间的天气条件、气柱水汽量、对流云回波(云顶高、强度等)特征、作业技术方法等进行分析与研究,得出江西省人工增雨作业的基本技术数据和指标,为江西省开展人工增雨抗旱作业提供科学依据.     

江西干旱期间人工增雨天气条件与潜力区分析

根据江西干旱期间的天气条件、气柱水汽量、对流云回波(云顶高、云强度等)特征、作业技术方法等进行分析与研究,得出江西省人工增雨作业的基本技术数据和指标,为江西省开展人工增雨抗旱作业提供科学依据.     

江西2003年夏季罕见高温气候特征及成因分析

对江西省2003年夏季罕见高温干旱的强度、气候历史地位、500hPa环流形势特征和海温特征等进行了分析。结果表明,2003年夏季高温强度在多项指标上均排建国以来第一位;在500hPa环流形势上具有特殊的分布特征;在前期环流形势场和海温场上具有一些前兆特征,有较好的预报意义。     

2003年浙北高温分析及预报

应用1960～2003年500hPa高度场及有关特征指数,分析其与浙北地区高温的关系,得出:高温频数更多地与前期西风槽系统关系密切,高温强度则与20°N以南印度洋至太平洋的辐合带呈高正相关,与4月欧亚经向环流指数为负相关。另外,入、出梅时间也是预示浙北高温的良好信号。2003年浙北高温出现时间早、持续时间长、范围大、强度强、危害严重为历史罕见,其中高温强度强是2003年有别于历年的最显著特征。     

713雷达回波资料在飞机增雨作业中的应用

概述了在干旱期间飞机和高炮人工增雨作业的最佳时机和方法。以2000年6-7月哈尔滨地区特大干旱为例，从卫星云图中的水汽图、红外和可见光云图上分析云系中的含水量、云顶温度、云系强度，并在此基础上利用天气雷达跟踪订正，认为利用卫星云图和雷达回波资料选择的作业时间和区域应是最佳的选择，获得了明显的效果。     

卫星云图、雷达回波在人工增雨时机选择中的应用

概述了干旱期间选择飞机和高炮人工增雨作业时机的方法，以2000年6～7月哈尔滨地区特大干旱期间进行的飞机和高炮人工增雨作业为例，利用卫星云图和雷达回波资料选择的作业时间和作业区域应是比较有利的。因为从卫星云图中的水汽图、红外和可见光云图上可分析出云系中的含水量、云顶温度、云系强度，在此基础上利用天气雷达跟踪订正，可直接指挥飞机和高炮在有利的区域和时间内进行作业，获得了明显的效果。     

莱州35年异常高温天气的统计分析

统计了莱州1971-2005年异常高温天气气候特征，并用1994-2003年相关环流资料进行分析，发现：在莱州异常高温过程期间，副热带高压西伸指数大，极涡指数偏小，西太平洋副热带高压是造成莱州夏季异常高温的主要影响系统。     

2009—2010年黔西南州特大干旱成因分析

2009年9月到2010年4月,黔西南州出现了特大干旱,是有气象资料记录以来最为严重的干旱灾害。该文利用黔西南8个县市台站的降水,NCEP/NCAR逐月再分析资料,分析从2009年9月到2010年4月持续干旱期间同期大气环流异常的特征。结果表明,持续干旱期间地面冷空气活动较常年偏东偏弱;西太平洋副热带高压脊线位置较常年偏西偏强;孟加拉湾的低值系统较常年偏弱,不活跃,使得暖湿气流不易北上;动力因子较常年同期偏弱,导致降水长时间持续偏少、气温持续偏高、蒸发量大,以上为黔西南州特大干旱发生的主要原因。     

Two Types of Flash Drought and Their Connections with Seasonal Drought

Flash drought is a rapidly intensifying drought with abnormally high temperature, which has greatly threatened crop yields and water supply, and aroused wide public concern in a warming climate. However, the preferable hydrometeorological conditions for flash drought and its association with conventional drought at longer time scales remain unclear. Here, we investigate two types of flash drought over China: one is high-temperature driven (Type I), while the other is water-deficit driven (Type II). Results show that the frequencies of the two types of flash drought averaged over China during the growing season are comparable. Type I flash drought tends to occur over southern China, where moisture supply is sufficient, while Type II is more likely to occur over semi-arid regions such as northern China. Both types of flash drought increase significantly (p0.01) during 1979-2010, with a doubled rise in Type I as compared with Type II. Composite analysis shows that high temperature quickly increases evapotranspiration (ET) and reduces soil moisture from two pentads before the onset of Type I flash drought. In contrast, there are larger soil moisture deficits two pentads before the onset of Type II flash drought, leading to a decrease in ET and increase in temperature. For flash drought associated with seasonal drought, there is a greater likelihood of occurrence during the onset and recovery phases of seasonal drought, suggesting perfect conditions for flash drought during transition periods. This study provides a basis for the early warning of flash drought by connecting multiscale drought phenomena.     

重庆市土壤水分盈亏与干旱关系研究

以重庆市所有气象站点近 3 6年的年、月平均温度和降水量等因子为基础 ,应用桑斯维特 (C·W·Thornthwait)修正式 ,模拟计算了土壤常年年、月水分盈亏量 ,同时根据气候干旱标准 ,分析了各类干旱的发生强度及分布规律 ,并进一步研究了土壤水分盈亏量与干旱强度之间的紧密关系 ,最后得出了重庆市所辖区域内各类干旱及其不同干旱程度的一般分布规律     

基于MODIS的温度植被干旱指数在四川盆地盛夏干旱监测中的适用性研究

基于卫星资料的温度植被干旱指数(TVDI)已被广泛应用于干旱监测,地表温度依赖于海拔高度,在地形复杂的四川省,如何将该指数更好的应用到业务干旱监测中,需进一步研究。本文利用MODIS数据,分析四川盆地2014年7月12～27日平均地表温度、植被指数、TVDI和100站土壤湿度的空间分布,并对比了它们之间的异同。研究结果表明,TVDI的空间分布主要由地表温度的空间分布决定,TVDI不仅可用于监测四川盆地较大范围的干旱状况,也可用于监测局地的干旱状况。当前自动站土壤湿度观测值与TVDI之间在有限点上不存在显著的线性相关,如何对TVDI进行干旱分级仍需深入研究。      

中国区域性骤发干旱特征分析

基于国家气象信息中心2 400多个观测站的候平均日最高气温、GLDAS 2.0/2.1的土壤湿度、蒸散发资料和ERA5的500 hPa位势高度、925 hPa风场再分析资料,定义了格点骤发干旱指数,在分析1979—2017年4—9月中国区域骤发干旱气候特征和骤发干旱指数的经验正交展开空间模态的基础上,确定骤发干旱发生频繁及变率大的区域,给出了区域性骤发干旱事件的识别标准,并对其演变过程进行合成分析,最后分析了典型个例的要素和环流特征。结果表明:骤发干旱多发于我国南方夏季,其中7月最多,以湖南和浙江地区发生最为频繁,这两个区域也是骤发干旱发生气候变率最大的区域。合成分析显示,高温是两个区域骤发干旱爆发的主要驱动因素:干旱爆发前一候,气温迅速升高,蒸散发快速增大,土壤湿度下降明显。2013年6—7月在湖南区域爆发了两次骤发干旱事件。第一次干旱爆发前,湖南地区500 hPa位势高度迅速增大,异常下沉气流导致降水减少和绝热增温,蒸散发随气温升高而增加,使土壤湿度减少,这次干旱由高温驱动;第二次干旱爆发前期,明显偏西、偏北且稳定的西北太平洋副热带高压使地表太阳净辐射通量增强、近地层的偏南气流使高温维持,蒸散发随降水而变化,这次干旱为降水减少所驱动,高温起促进作用。     

三江平原土壤湿度记忆性及其与水热气候条件的关系

利用1982—2020年三江平原19个国家气象观测站土壤湿度及同期降水、气温数据, 基于相关系数和自相关系数统计方法, 分析了黑龙江省三江平原土壤湿度记忆性及与降水、气温之间的关系。结果表明: 春、夏季三江平原土壤湿度记忆时间均在10—40 d, 各层土壤湿度记忆性的空间分布以中间层(10—20 cm)土壤湿度平均记忆时间最长, 呈上下层递减的趋势; 春季三江平原10—20 cm土层土壤湿度的记忆时长平均20 d, 夏季平均17 d; 夏季土壤湿度记忆性强度大于春季, 空间分布以三江平原西部的记忆性较强, 随着土层的增加土壤湿度记忆性有增大的趋势。降水是三江平原土壤湿度主要来源, 受降水和气温协同作用的影响, 夏、秋季土壤湿度与同期降水量、温湿指数均存在显著的正相关关系; 春季土壤湿度与前期秋冬季降水亦呈显著正相关, 与前期温湿指数呈负相关, 前期秋冬季气温的升高会促进土壤的融冻, 从而使当年春季土壤水分增加。     

不同品种双季晚稻产量结构对干旱胁迫的响应

干旱是湖南双季晚稻分蘖-幼穗分化期主要农业气象灾害,对晚稻生长和产量形成产生不利影响。本研究以常规晚稻和超级晚稻在分蘖-幼穗分化期进行干旱胁迫试验,于20142016年连续3年开展15、20、25、30d4个干旱处理水平试验,探讨了干旱强度与不同品种双季晚稻产量结构的关系,从而确定双季晚稻干旱指标。试验研究结果表明,相同干旱胁迫处理下,土壤相对湿度是影响双季晚稻产量结构的关键因素,常规晚稻和超级晚稻产量结构对干旱胁迫的响应存在差异性。自晚稻分蘖普遍期开始干旱处理,对常规晚稻理论产量、有效穗数和结实粒数产生不利影响的土壤相对湿度阈值分别为92.5%、87.2%和98.6%;对超级晚稻理论产量、有效穗数和结实粒数产生不利影响的土壤相对湿度阈值分别为96.8%、97.1%和89.3%。根据晚稻产量结构对干旱持续时间和土壤湿度的响应,构建了常规晚稻和超级晚稻的分蘖-幼穗分化期干旱等级指标,可为双季晚稻的干旱监测和抗旱救灾提供理论依据和实践指导。     

Impacts of extreme weather on wheat and maize in France: evaluating regional crop simulations against observed data

Extreme weather conditions can strongly affect agricultural production, with negative impacts that can at times be detected at regional scales. In France, crop yields were greatly influenced by drought and heat stress in 2003 and by extremely wet conditions in 2007. Reported regional maize and wheat yields where historically low in 2003; in 2007 wheat yields were lower and maize yields higher than long-term averages. An analysis with a spatial version (10?×?10?km) of the EPIC crop model was tested with regards to regional crop yield anomalies of wheat and maize resulting from extreme weather events in France in 2003 and 2007, by comparing simulated results against reported regional crops statistics, as well as using remotely sensed soil moisture data. Causal relations between soil moisture and crop yields were specifically analyzed. Remotely sensed (AMSR-E) JJA soil moisture correlated significantly with reported regional crop yield for 2002–2007. The spatial correlation between JJA soil moisture and wheat yield anomalies was positive in dry 2003 and negative in wet 2007. Biweekly soil moisture data correlated positively with wheat yield anomalies from the first half of June until the second half of July in 2003. In 2007, the relation was negative the first half of June until the second half of August. EPIC reproduced observed soil dynamics well, and it reproduced the negative wheat and maize yield anomalies of the 2003 heat wave and drought, as well as the positive maize yield anomalies in wet 2007. However, it did not reproduce the negative wheat yield anomalies due to excessive rains and wetness in 2007. Results indicated that EPIC, in line with other crop models widely used at regional level in climate change studies, is capable of capturing the negative impacts of droughts on crop yields, while it fails to reproduce negative impacts of heavy rain and excessively wet conditions on wheat yield, due to poor representations of critical factors affecting plant growth and management. Given that extreme weather events are expected to increase in frequency and perhaps severity in coming decades, improved model representation of crop damage due to extreme events is warranted in order to better quantify future climate change impacts and inform appropriate adaptation responses.     

鲁西南历年逐旬土壤自然干旱程度序列模型

近30多年来,由于农田灌溉条件的迅速改善,得到的土壤墒情资料已不能反映自然状态下的土壤墒情变化规律。利用土壤水分平衡方程和Penman公式等计算各旬土壤水分相对盈亏程度并对照2001~2003年在不浇水条件下得到的各旬土壤墒情资料,建立拟和方程,确定了干旱指标,恢复了1970~2003年的逐旬实际干旱序列。结果表明,模拟的逐旬干旱序列较好地滤出了灌溉因素,与实际自然土壤自然干旱程度接近。     

高分辨率WRF模式中土壤湿度扰动对短期高温天气模拟影响的个例研究

本文利用WRFV3.6中尺度预报模式就土壤湿度扰动对2003年7月22~23日和29~30日短期高温天气过程的影响进行了高分辨率模拟研究。结果表明:(1)WRF模式地表气温对土壤湿度扰动有较强的敏感性,且随着土壤湿度的增加(减小)而降低(升高)。同时,模式中土壤湿度对地面气温影响的强度对模式分辨率具有较高的依赖性。(2)不同模式分辨率下气温随土壤湿度变化的规律一致;由于更高分辨率的地形资料的应用,提高分辨率可在较大程度上改善模拟效果。(3)不同土壤湿度试验模拟的地表感热、潜热通量可直接影响气温变化;(4)土壤湿度扰动通过间接影响高温发展的近地层各物理过程使得地表气温发生变化。这些过程中,对流(平流)过程在全天表现为增温(冷却)的作用,强度在白天均随土壤湿度的减小而增加。在较干的土壤条件下,非绝热增温在白天的主导地位加强;在夜间,非绝热冷却的强度减弱,且小于占据主导的对流绝热增温的强度。以上结果表明,在模拟和预报高温天气时土壤湿度非常重要,也意味着通过土壤湿度扰动的集合预报方法来改进模式高温模拟预报具有较大的潜力。     

Evolution of geophysical parameters over the Indian Ocean region during contrasting monsoon years of 2002 and 2003 using TRMM/TMI data

Summary The evolution of geophysical parameters over Indian Ocean during two contrasting monsoon years 2002 (drought) and 2003 (normal) were studied using TRMM/TMI satellite data. Analysis indicates that there was a lack of total water vapour (TWV) build up over Western Indian Ocean (WIO) during May 2002 (drought) when compared to 2003 (normal). Negative (positive) TWV anomalies were found over the WIO in May 2002 (2003). In 2002, negative SST anomaly of ∼1.5 °C is found over entire WIO when compared to 2003. Anomalously high sea surface wind speed (SWS) anomaly over the South West Indian Ocean (SWIO) and WIO would have resulted in cooling of the sea surface in May 2002 in comparison to 2003. In 2003 the wind speed anomaly over entire WIO and Arabian Sea (AS) was negative, whereas sea surface temperature (SST) anomaly was positive over the same region, which would have resulted in higher moisture availability over these regions. A negative (positive) TWV anomaly over Eastern Arabian Sea (EAS) and positive (negative) anomaly over WIO forms a dipole structure. In the month of June no major difference is seen in all these parameters over the Indian Ocean. In July 2002 the entire WIO and AS was drier by 10–15 mm as compared to 2003. The pentad (5 day) average TWV values shows high (>55 mm) TWV convergence over EAS and Bay of Bengal (BoB) during active periods of 2003, which gives high rainfall over these regions. However, during 2002 although TWV over BoB was >55 mm but it was ∼45–55 mm over EAS during entire July and hence less rainfall. The evaporation has been calculated from the bulk aerodynamic formula using TRMM/TMI geophysical products. It has been seen that the major portion of evaporative moisture flux is coming from southern Indian Ocean (SIO) between 15 and 25° S. Evaporation in June was more over AS and SIO in 2003 when compared to 2002 which may lead to reduce moisture supply in July 2002 and hence less rainfall compared to July 2003.