2011年1月大气环流和天气分析

2011年1月大气环流主要特征如下:北半球极涡中心位于北美北部,强度比常年同期偏弱.中高纬度地区环流呈现三波型分布,东亚大槽、北美槽强度偏弱,西欧槽接近常年同期,东亚锋区明显南压.南支槽位于90°E附近,强度与常年相当.西北太平洋副热带高压明显偏弱.1月主要气候特点:全国平均气温为-8.3℃,比常年同期(-5.9℃)偏低2.4℃,全国平均降水量为8.2 mm,比常年同期(12.1 mm)偏少3.9 mm.华北、黄淮等地区干旱持续发展,冷空气活动频繁,南方雨雪冰冻灾害严重.月内有3次中等强度冷空气及6次降水过程.     

2012年10月大气环流和天气分析

2012年10月环流特征如下:北半球高纬度地区为单一极涡,强度较常年同期偏弱,中高纬环流呈现4波型,欧亚地区中高纬环流经向度较常年偏大,南支槽偏强,西太平洋副热带高压强度偏弱.10月,全国平均降水量为29.1 mm,比常年同期(36.9 mm)偏少18.9％,全国平均气温为10.3℃,与常年同期(10.3℃)持平.月内,冷空气活动频繁,先后有4次冷空气过程影响我国;受台风山神影响,我国华南地区出现一次强降水过程;西南地区阴雨寡照天气及华南秋旱天气持续,在中下旬均有所好转;我国中东部大部地区出现雾霾天气;个别地区出现低温冰冻、局地洪涝及风雹灾害.     

2010年10月大气环流和天气分析

2010年10月大气环流特征是:北半球高纬度地区存在两个极涡中心,强度偏弱;中高纬呈现4波型,其中乌拉尔山高压脊偏强,对应大片40 gpm的正距平区;副高强度偏弱.全国平均气温为10.1℃,比常年同期(9.6℃)偏高0.5℃.全国平均降水量为42.6 mm,比常年同期(37.0 mm)偏多15.1%.月内我国主要天气事...     

2013年1月大气环流和天气分析

2013年1月大气环流特征为:北半球极涡呈偶极型,极涡范围及强度较常年偏弱,中高纬环流呈三波型,欧亚大陆槽位于西西伯利亚,位置偏北,引导多股冷空气影响我国北方,月内中高纬环流形势调整较大,上旬以经向型环流为主,中下旬则转为纬向型环流;西太平洋副热带高压接近常年同期,东亚大槽位于西北太平洋西岸,较常年偏强,南支槽位于90°E附近,较常年略偏弱.2013年1月,全国平均气温为-5.2℃,略低于常年同期(-5.0℃).月内气温阶段性调整明显,上旬,较同期偏低3℃,下旬,较同期偏高1.7℃.全国平均降水量为6.5 mm,较常年同期(13.2 mm)偏少50.8％.月内出现一次强冷空气过程,雾霾天气频繁,共出现3次较大范围雾霾过程.南方部分地区遭受低温雨雪冰冻灾害,北方局地遭受雪灾,云南大部、贵州西部及四川南部等地气象干旱持续.     

2011年6月大气环流和天气分析

2011年6月环流特征如下：北半球高纬度地区为单一极涡,强度较常年同期偏弱,西太平洋副热带高压较常年偏强,欧亚中高纬环流较平直,多短波槽活动,季风槽较常年略偏弱,槽前西南气流明显。6月,全国平均降水量为102.8mm,比常年同期（97.1mm）偏多5.9%。全国平均气温为20.5℃,比常年同期（19.5℃）偏高1.0℃。月内,我国主要天气气候事件有：长江中下游、华南、西北地区东南部、川渝地区、华北、黄淮、东北南部等地发生暴雨洪涝;有3个热带气旋生成并登陆我国;黄淮等地出现极端高温天气;西北东部、华北、黄淮、江淮北部等地上中旬气象干旱持续发展,下旬干旱缓解;全国23个省（市、区）遭受风雹灾害。     

2021年3月大气环流和天气分析

2021年3月大气环流呈双极型分布,中高纬环流为三波型,东亚大槽偏弱,西太平洋副热带高压强度与常年相当。3月全国平均气温为6.6℃,较常年同期(4.1℃)偏高2.5℃,为1961年以来同期第二高。全国降水量为27.8 mm,较常年同期(29.5 mm)偏少6%。本月有3次大范围沙尘天气过程,较常年偏强偏多,其中13—18日为近十年我国最强沙尘天气过程。强对流天气偏少,仅月底在长江流域发生一次强对流天气过程。月内冷空气偏弱,仅于15—17日发生一次中等强度冷空气过程。云南等地干旱持续,华南干旱开始发展。     

2017年5月大气环流和天气分析

2017年5月大气环流的主要特征是极涡偏强且呈单极型分布,中高纬环流呈多波型,西太平洋副热带高压强度较常年偏强,南支槽强度较常年偏弱。5月全国平均气温17.1℃,较常年同期偏高0.9℃,为1961年以来第4高;全国平均降水量59.4 mm,比常年同期（69.5 mm）偏少14.5%,但5月7日广州出现破历史极值的极端强降水。月内我国南方地区有5次区域性暴雨天气过程;北方出现极端高温过程;东北西部、华北等地发生严重气象干旱;北方地区有2次沙尘天气过程。     

2021年4月大气环流和天气分析

2021年4月中高纬大气环流为三波型,极涡呈单极偏心型分布,强度偏强,西太平洋副热带高压强度较常年偏弱,南支槽较常年偏强。4月主要天气气候特点是全国平均气温为11.1℃,较常年同期偏高0.1℃;全国平均降水量为42.5 mm,较常年同期(45.1 mm)偏少5.8%,其中青海平均月降水量为历史同期第一多。月内,我国遭受四次冷空气过程影响;西南和华南东部气象干旱持续或发展;北方地区出现两次沙尘天气过程;多地遭受风雹袭击,部分地区受灾较重。     

2012年2月大气环流和天气分析

2012年2月大气环流特征为：北半球极涡呈双极型,中心分别位于加拿大东北部和鄂霍茨克海附近,后者强度较常年平均明显偏强;中高纬环流呈经向型,乌拉尔山附近维持阻塞高压活动,强度偏强;平均南支槽位于90°E附近,接近多年平均位置,强度偏弱。2012年2月全国平均气温-3.2℃,较1月-7.2℃明显回暖,但比常年同期（-2.0℃）偏低1.2℃。全国平均降水量为14.5 mm,较1月16.8 mm减少2.3 mm,较常年同期（17.6mm）偏少3.1 mm。月内出现三次全国范围的中等以上强度冷空气过程,以及三次降水过程。西藏南部出现极端降水事件,云南和四川西南部的气象干旱发展,南方大部继续低温阴雨寡照天气。     

2017年2月大气环流和天气分析

2017年2月大气环流的主要特征是极涡偏强且呈单极偏心型分布,中高纬环流呈3波型,西太平洋副热带高压强度接近常年,南支槽强度较常年偏弱。2月全国平均气温0℃,较常年同期偏高1.7℃;全国平均降水量14.4 mm,比常年同期（17.4 mm）偏少17.1%。2月我国有两次强冷空气过程;3次降水过程,其中新疆出现了一次暴雪过程,日降水量打破历史极值;中东部出现两次雾 霾天气。     

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.     

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.     

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.     

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正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted     

A Brief Introduction to Marine Meteorological Science Experiment Base at Bohe Town,Maoming City,Guangdong Province

<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea.     

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AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences