Models-3/CMAQ模式对郑州市大气污染物的预报分析研究

介绍了美国国家环保局第三代空气质量模式(Models-3)的主要组成部分:气象模式系统、排放模式系统以及公共多尺度模式系统(CMAQ)。并对郑州市SO2和NO2观测值与Models-3/CMAQ预报值进行对比分析,结果表明:模式可以模拟出郑州市SO2和NO2的同位相变化规律;预报值存在系统性偏低的现象;随着预报时效的延长,对SO2和NO2的预报效果逐渐变差。     

Models-3/CMAQ模式对郑州市大气污染物的预报分析研究

介绍了美国国家环保局第三代空气质量模式(Models-3)的主要组成部分:气象模式系统、排放模式系统以及公共多尺度模式系统(CMAQ).并对郑州市SO2和NO2观测值与Models-3/CMAQ预报值进行对比分析,结果表明:模式可以模拟出郑州市SO2和NO2的同位相变化规律;预报值存在系统性偏低的现象;随着预报时效的延长,对SO2和NO2的预报效果逐渐变差.     

2008年北京奥运交通限制效果的模式研究

利用美国国家环保署(EPA)开发的区域多尺度空气质量模式Models-3/CMAQ研究了北京城区奥运交通限行期间VOC、NOX和O3的浓度变化状况。结果表明:Models-3/CMAQ模式能够较好地反映VOC、NOX和O3浓度的变化趋势;交通限行造成的机动车排放源削减使北京奥运期间大气VOC浓度平均减少约12%,NOX浓度平均减少约21%,而O3浓度则平均增加约22%。     

北京及周边地区一次大气污染过程的数值模拟

利用中尺度气象数值模式MM5与第三代空气质量模式系统Models-3／CMAQ,对2002年10月北京及周边地区一次典型大气污染过程进行数值模拟研究,并对其形成原因进行了分析。结果表明,污染物PM。模拟峰值出现时间与实际观测浓度峰值出现时间较为一致,模式的模拟效果较好。北京地区PM10浓度除受北京当地排放源的影响外,在特殊气象条件下,外地污染源对北京地区PM10的影响也比较大。要控制北京地区PM10浓度,除了控制北京当地的排放源外,对外地污染源的控制也需要给予高度重视。     

离岸型背景风和海陆风对珠江三角洲地区灰霾天气的影响

不同类型的背景场和海陆风对珠江三角洲地区大气灰霾有不同的影响。作者主要利用空气质量模式系统Models-3 (MM5/SMOKE/CMAQ)研究离岸型背景风和海陆风对珠江三角洲一次灰霾天气的影响, 结果表明, 中尺度气象模式MM5对珠江三角洲地区这次灰霾天气的气象模拟, 较好地模拟了风速和风向的变化。多尺度空气质量模式CMAQ模拟出了PM10浓度的变化, 与观测值比较一致。在这次灰霾天气过程中, 由于离岸型背景风与陆风风向一致, 在陆风维持的情况下, 内陆源区的PM10被输送到沿海地区, 导致沿海城市和海面上PM10浓度比较高; 而在海风维持的情况下, 海风与离岸型背景风方向相反, 造成海风较小, 致使整个珠江三角洲地区灰霾天气都比较严重。敏感性试验结果表明离岸背景风和海陆风的相互作用对灰霾天气的生成与分布有重大的影响。     

应用Models-3/CMAQ模式对华北地区一次强沙尘天气的研究初探

根据2002年在ACE-Asia和TRACE-P试验中获得的亚洲区域污染源排放资料,结合由MICAPS能见度观测资料估算而得的颗粒物排放资料,利用美国EPA最新发展的Models-3/CMAQ模式系统,模拟研究了2002年3月华北地区发生的一次强沙尘暴个例.结果表明,(1)模拟的各气态污染物的时空演变及相互关系与已有的观测结果基本一致.(2)颗粒污染物的模拟结果也反映了已有的观测事实,粗细颗粒物呈一致的先降后升日变化趋势;沙尘过程前期,颗粒物污染主要来源于近地面污染源;沙尘期间,颗粒物污染主要源自外界沙尘的高空输送,且粗颗粒物污染是此次过程的首要颗粒污染.(3)该模式系统可用于沙尘气溶胶研究的进一步开发与利用.     

一次大雾天气下PM2.5二次无机粒子的数值模拟

利用多尺度空气质量模式系统（Models-3/CMAQ）对2002年12月1—3日北京及周边地区发生的一次大雾天气进行数值模拟,分析了大雾天气下PM2.5二次无机粒子的演变及其影响。结果表明,白天相对湿度降低,雾滴蒸发脱水后PM2.5二次无机粒子会悬浮在大气中;夜间在水汽凝结成雾滴的过程中,大量的PM2.5二次无机粒子提供了充足的凝结核,促进大雾天气的进一步发展。午后PM2.5二次无机粒子积聚及较高的相对湿度是造成北京及周边地区低能见度的重要原因,并推断该区域很可能是霾天气。     

长白山高压对辽宁中部城市群大气污染影响的数值模拟

利用新一代空气质量模式系统Models-3,通过改变模式中长白山山脉区域地形高度,对比分析长白山高压以及辽宁中部城市群5城市气象环境要素的变化情况。结果表明,改变地形后,原来较强的长白山高压有了明显的减弱,城市群5城市的水平气流辐合场消失,风速增大,逆温强度也减弱,有利于污染物的传输扩散;模拟结果也表明污染物浓度有明显的降低,试验较好地揭示了长白山高压对辽宁中部城市群大气污染的影响机制。     

海洋环流模式模拟自然 和核辐射14C的分布

放射性14C在海洋环流研究和人为CO2问题的研究中都有重要地位。本文用海洋环流模式模拟了海洋中自然14C的分布及海洋对核辐射产生的放射性14C的吸收, 以期对海洋吸收人为CO2的能力做一初步的研究。模拟的海洋环流结果与观测相比符合得较好,成功地模拟出了北大西洋深水（NADW）、南极底水 (AABW）等基本特征。对自然14C的模拟揭示出了海洋通风的基本特征。模拟出的沿GEOSECS 路径的南、北垂直截面与观测结果符合得较好。对核辐射14C的模拟表明:模式模拟的沿GEOSECS 路径的南、北垂直截面与观测结果符合得较好;模拟出的海洋表面核辐射浓度与观测值一致,但核辐射14C在海洋中的柱存量和平均穿透深度都比观测结果要小。文中分析了造成这种差异的可能原因。     

台湾岛地形对“麦德姆”台风的影响

采用WRF模式,以2014年10号台风"麦德姆"为例,针对台湾岛中央山脉的局部地形,设计精细化地形试验,数值模拟了"麦德姆"台风登陆台湾岛前后地形对其路径、强度及风雨分布的影响。研究结果表明:真实的地形能更好的模拟和再现"麦德姆"台风发生发展的过程;台湾岛中央山脉地形对登岛"麦德姆"台风的路径有实质性的影响,降低台湾地形高度试验导致台风路径向西南偏转,而提高台湾岛地形高度则导致台风路径向东北偏转,地形高度改变的程度与路径偏转程度成正相关,地形高度改变所导致阻挡效应及台风环流与大尺度环流的相互作用是导致路径偏转的主要原因;台湾岛地形高度的改变对台风强度有明显的影响,增加或减少台湾岛地形高度,都会使台风强度有所减弱,这与地形变化引起的动力狭管效应、云水物质分布及外围云带的对流运动有关;台湾岛地形影响"麦德姆"台风降水的机制更为复杂,其不仅与地形引发的台风强度及结构变化有关,更与地形引起的眼区对流活动和螺旋云带及外围云系的时空分布有关。     

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.     

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.     

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.     

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