阶段性干旱对夏玉米生长发育及产量的影响

本试验通过可移动遮雨棚对大田夏玉米不同生长阶段土壤湿度进行定量控制,分析了拔节—抽雄和抽雄—成熟期干旱胁迫对玉米生长发育及产量构成等要素的影响。结果表明,玉米受干旱胁迫后,植株生长发育受到抑制,产量明显降低。拔节—抽雄期干旱对玉米营养生长阶段植株性状的影响较大;抽雄—成熟期干旱对玉米营养生长的影响相对较小,但对产量影响较大,其中穗长、穗粒数、穗总重和穗粒重较对照处理均显著减小,穗粗、秃尖比及百粒重变化不显著。     

基于实际蒸散量辽西地区春玉米生物量及产量评价

为了确定辽西地区春玉米各发育阶段生长状况及最终产量的评价方法,基于2011—2015锦州农业气象试验站开展的玉米分期播种试验,利用锦州地区气象观测数据、玉米发育期数据和玉米各发育阶段地上生物量及产量数据,采用Penman-Monteith方法和数理统计方法分析锦州地区玉米不同发育阶段实际蒸散量与地上气象生物量和气象产量的相关关系,并建立玉米各发育期生长状况及最终产量评估模型。结果表明:2011—2015年锦州地区玉米各发育阶段实际蒸散量与地上气象生物量和气象产量之间的线性关系显著,播种—七叶阶段二者呈显著的相关关系(P0.05),播种—拔节、播种—抽雄、播种—乳熟和播种—成熟阶段二者呈极显著的相关关系(P0.01)。建立的玉米各发育期生长状况及产量评估模型的预报准确率为77.8%—94.5%。辽西地区玉米正常生长全生育期水分供应的下限为333.2 mm,其中播种—七叶、七叶—拔节、拔节—抽雄、抽雄—乳熟和乳熟—成熟阶段水分供应的下限分别为49.9 mm、23.3 mm、83.4 mm、118.9 mm、57.7 mm。玉米各发育阶段干旱对产量影响的程度由重至轻依次为:拔节—抽雄抽雄—乳熟七叶—拔节播种—七叶乳熟—成熟。本文基于玉米实际蒸散建立的辽西地区春玉米生物量及产量评估方法,可以满足农业气象产量预报服务的需求,在实际业务中具有应用价值。     

干旱对夏玉米根冠及产量影响试验

为揭示干旱对夏玉米根冠生长及产量形成的影响,2013—2015年在山东夏津、山西运城和河北固城开展夏玉米水分胁迫控制试验,研究不同干旱条件下玉米根冠及产量的变化,厘定干旱敏感时段及临界阈值。结果表明:同一干旱程度,影响玉米地上干物重、产量的关键时段为拔节-抽雄期,抽雄期最敏感,影响根系、根冠比的关键时段为出苗-拔节期,拔节期最敏感。不同干旱程度,在快速失墒阶段,不同生育时段的地上干物重、根干重、根冠比均呈下降趋势,分别较对照减少11.7%~67.8%,35.2%~85.8%和15%~62%;干旱维持阶段与快速失墒阶段相比,地上干物重呈持续下降趋势,较对照减少24.3%~89.7%,根干重、根冠比呈上升趋势或无明显差异,分别较对照减少9.7%~80.8%,9.6%~62%。出苗-拔节期,土壤相对湿度60%~62%为玉米地上部生长及形成合理根冠比的临界阈值;出苗-七叶期,土壤相对湿度51%~60%利于根系生长。土壤相对湿度62%为影响玉米产量的临界阈值,土壤相对湿度31%~40%,出现在拔节、抽雄等敏感期,玉米减产七成以上。土壤相对湿度50%~60%持续时间少于8 d,复水后根冠可迅速恢复生长,但对产量仍有一定程度的影响,减产1.4%~6.6%。     

夏玉米在充分供水条件下不同生育期作物系数研究

利用2014年6—10月夏玉米全生育期试验数据和气象数据,采用LG型称重式蒸渗仪分析了在充分供水条件下陕西关中地区夏玉米全生育期最大耗水量及不同生育期的作物系数。结果表明：夏玉米在试验地段从播种到收获共119 d,充分供水条件下夏玉米全生育期最大耗水量599.9 mm。玉米实际蒸发蒸腾量（ET）与参考蒸散量（ET0）的逐日变化趋势倾向率除三叶—七叶期以外,其余时间段呈现出一致性;全生育期日平均ET为5.0 mm/d,抽雄—乳熟期的ET最大,占全生育期的33.2%。夏播玉米各生育期（播种—三叶、三叶—七叶、七叶—拔节、拔节—抽雄、抽雄—乳熟、乳熟—收获）作物系数分别为0.64,0.76,0.80,1.38,1.47,1.58。     

拔节和抽雄期间涝渍对夏玉米生长的影响

通过对夏玉米拔节和抽雄期间进行不同时间灌水处理,研究洪涝对夏玉米生长状况和最终产量的影响程度。结果表明：玉米在拔节和抽雄期间充足的水分条件下,可以促进玉米的高度生长。玉米在拔节期间灌水5d和在抽雄期间灌水3d,5d的产量均高出对照区的产量。     

河南省夏玉米生长季水分供需时空变化特征

水分条件是制约河南夏玉米高产稳产的重要因素,本文利用河南省夏玉米生长季30个农业气象观测站1961～2011年逐日气象观测资料,计算不同生育阶段夏玉米需水量和水分亏缺量,分析其近50a的水分供需条件时空变化特征。结果表明：夏玉米各生育阶段需水量呈显著的下降趋势;各生育阶段之间水分亏缺量没有显著的年际变化。分析各生育阶段水分供需情况,水分亏缺量为正值表明水分供给不足,为负值表示水分有盈余,出苗一拔节期夏玉米水分亏缺量以负值为主,拔节一抽雄期正负交替各占一半,抽雄一乳熟期和乳熟-成熟期以正值为主。空间分布上,夏玉米各生育阶段需水量与各地海拔高度呈显著负相关,全生育期负相关系数为0．799;各阶段水分亏缺量也有一定的相似性,水分亏缺地区主要分布在豫西和豫西北大部,水分较充足的地区主要分布在漯河、南阳、驻马店等地。     

沈阳春玉米不同生育阶段需水量及缺水量变化特征

基于1960—2016年沈阳5个气象观测站玉米发育期资料及气象观测资料,计算春玉米不同生育阶段需水量、有效降水量,进而计算水分盈亏指数并分析其变化特征。结果表明:沈阳市春玉米除播种—出苗、出苗—七叶及拔节—抽雄期有效降水量呈增加趋势,其他发育阶段及全生育期呈显著减少趋势;全生育期及各生育阶段需水量均呈下降趋势;全生育期缺水量总体以下降为主,其中拔节—抽雄期处于强下降趋势,播种—出苗和出苗—七叶期呈弱下降趋势。沈阳北部有效降水量偏少、需水量偏高,是缺水量高值区;拔节—抽雄期缺水量最大。     

播期对浚单20夏玉米生长状况及产量影响分析

通过对浚单20玉米新品种进行分期播种试验,研究不同播期对浚单20各个阶段生长状况及产量形成的影响.首先对各播期发育阶段持续日数进行差异性检验,结果表明,夏玉米全生育期日数随播期推迟而缩短.其次,分析了作物各发育期持续日数与各气象要素的关系:在一定的范围内,温度升高可以促进夏玉米生长,日照减少可加快夏玉米生育进程,不同生育阶段降水量对作物生长影响不同,其中抽雄-乳熟期降水量增加能缩短发育日数.然后,对比分析了播期对浚单20干物质及产量形成的影响:随着播期推迟,穗长有缩短趋势,单株籽粒重、百粒重、籽粒与茎秆比也随播期的推迟呈下降趋势;播期一平均实产达864.12g/m2,比播期二高74.56 g/m2,比播期三高128.33g/m2,在一定程度上说明浚单20适时早播,有助于产量提高.     

富裕县农田土壤湿度变化及其对玉米发育期和产量的影响

本文旨在分析黑龙江省富裕县农田土壤相对湿度对玉米发育期和产量的影响,以期为松嫩平原西部玉米生产提供科学参考。以黑龙江省富裕县为研究区域,利用1982—2017年土壤相对湿度资料、1995—2017年玉米发育期资料、玉米产量资料,采用对比分析、相关分析、Mann-Kendall突变检验法,分析土壤相对湿度变化特征,研究土壤相对湿度对玉米发育期和产量的影响。结果表明：富裕县近36 a土壤相对湿度呈增加—减小—增加的趋势。播种期—出苗期、拔节期—抽雄期、乳熟期—成熟期土壤干旱平均每4—6 a一遇,抽雄期—乳熟期每2—3 a一遇,出苗期—拔节期土壤基本无旱。各发育期土壤相对湿度减小的突变年在1987年前后,增加的突变年在2013年前后。20世纪80年代土壤较适宜,干旱轻,90年代土壤相对湿度迅速下降,干旱最重,之后随着年代的推移土壤干旱逐渐减轻。玉米主要发育期中播种期—出苗期、出苗期—拔节期土壤干旱对产量影响较小,拔节期—成熟期是土壤干旱影响产量的主要时期。     

干旱胁迫对夏玉米叶片光合及叶绿素荧光的影响

选用华北地区大面积种植的夏玉米品种郑单958、承玉2号、鲁单981作为试验材料,通过研究干旱胁迫条件下的玉米叶片光合、叶绿素荧光等指标随着土壤水分的动态变化规律,以期为夏玉米干旱的生理生态变化监测及水分高效利用提供理论依据.研究发现,在土壤含水量70%左右时,随着土壤相对湿度的下降,上述3个夏玉米品种仍能保持其叶片水分状态.郑单958、承玉2号、鲁单981的叶片净光合速率在土壤水分中等条件下最大,分别为39.9、38.8、38.4 μmol CO2/m2 · s;在土壤相对湿度较低时,郑单958、承玉2号、鲁单981的叶片净光合速率下降趋势明显(P＜0.05).叶片水势变化规律为:在土壤相对湿度＞90%时,对水分胁迫郑单958、承玉2号不敏感,鲁单981敏感;在土壤相对湿度＜70%时,水分胁迫条件下承玉2号不敏感,而鲁单981、郑单958敏感.气孔导度(gs)变化规律:随着水分胁迫加剧,3个夏玉米品种气孔导度均下降,在土壤水分较高时,气孔导度变化规律不明显,在土壤水分较低时,气孔导度明显下降(P＜0.01),细胞间隙CO2浓度(Ci)随土壤水分胁迫加剧而上升.上述结果表明:与叶片的光合和水分状况相比,夏玉米的气孔对土壤水分的匮缺更为敏感.     

COMPARATIVE ANALYSIS OF VARIOUS DATA OF AIR–SEA TEMPERATURE DIFFERENCE AND ITS VARIATION ACROSS SOUTH CHINA SEA IN THE PAST 35 YEARS

Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.     

IMPACT OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION ON THE IMMIGRATION OF NILAPARVATA LUGENS(STL) IN HUNAN AND JIANGXI PROVINCES

Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.     

A COMPARATIVE ANALYSIS OF ATMOSPHERIC AND OCEANIC CONDITIONS BEFORE THE OCCURRENCE OF TWO TYPES OF EL NIO EVENTS

The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o.     

Could the Recent Taal Volcano Eruption Trigger an El Ni?o and Lead to Eurasian Warming?

正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment.     

VARIABILITY OF INTER-ANNUAL RELATIONSHIP BETWEEN INDIAN OCEAN DIPOLE AND HUAXI REGION’S AUTUMN PRECIPITATION

The moving-window correlation analysis was applied to investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the synchronous autumn precipitation in Huaxi region, based on the daily precipitation, sea surface temperature (SST) and atmospheric circulation data from 1960 to 2012. The correlation curves of IOD and the early modulation of Huaxi region’s autumn precipitation indicated a mutational site appeared in the 1970s. During 1960 to 1979, when the IOD was in positive phase in autumn, the circulations changed from a “W” shape to an ”M” shape at 500 hPa in Asia middle-high latitude region. Cold flux got into the Sichuan province with Northwest flow, the positive anomaly of the water vapor flux transported from Western Pacific to Huaxi region strengthened, caused precipitation increase in east Huaxi region. During 1980 to 1999, when the IOD in autumn was positive phase, the atmospheric circulation presented a “W” shape at 500 hPa, the positive anomaly of the water vapor flux transported from Bay of Bengal to Huaxi region strengthened, caused precipitation ascend in west Huaxi region. In summary, the Indian Ocean changed from cold phase to warm phase since the 1970s, caused the instability of the inter-annual relationship between the IOD and the autumn rainfall in Huaxi region.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.     

Revisiting the Concentration Observations and Source Apportionment of Atmospheric Ammonia

正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on