北方风沙肆虐南方阴雨连绵——2001年4月

4月份 ,我国冷空气活动比较频繁 ,受此影响 ,北方地区风沙频繁 ,月内共有 8次扬沙或沙尘暴天气 ,气温变化幅度较大 ,局部地区出现冷 (冻 )害 ;南方大部降水与常年持平 ,局部地区出现了暴雨、冰雹等强对流天气。北方部分地区干旱发生或发展。1　天气概况1 .1　降水4月 ,我国出现 4次较大范围的降水。与常年同期相比 (如图 1 ) ,青藏高原中部及新疆北部等地偏多 5成至 1倍 ;全国其余大部地区接近常年或偏少。就旬而言 ,上旬 ,由于受冷空气频繁袭击 ,新疆北部降水量有 1 0～2 0 mm,较常年同期偏多 ,江南大部、华南东部降水量一般有 2 5～ 6 0 m…     

北方晴暖风沙肆虐南方寡照阴雨绵绵

每月气候与影响3月份 ,全国大部地区气温偏高 ;北方地区降水偏少 ,黄淮中部和西部以及关中和陇东部分麦区旱象露头或发展 ,冬小麦返青分蘖和孕穗受到影响。西南东部、江南大部以及华南北部和西部上旬和中旬持续阴雨寡照天气 ,不利于春播春耕和越冬作物的生长 ,西南东部出现局地湿害。月内 ,北方地区多次出现大范围的大风扬沙或沙尘暴天气 ,给交通运输和人们日常生产生活带来不便。1　北方大部地区大风扬沙天气频繁入春以来 ,我国北方大部地区降水稀少、温度偏高 ,除东北东部、甘肃南部和内蒙古的部分地区有 10～ 40 mm降水外 ,大部地区降水…     

北方气温偏高 南方阴雨连绵

北方气温偏高南方阴雨连绵－１９９４年２月－唐惠芳（中央气象台，北京１０００８１）本月，由于冷空气活动较弱，北方大部地区气温偏高，南方大部地区气温接近常年；月内，南方大部地区阴雨连绵，长江中下游、淮河流域大部、西北地区东部及云南等地降水偏多。１天气概况...     

北方干旱少雨 南方阴雨连绵

本月春暖,中旬华北气温显著偏高;上中旬北方冬麦区干旱少雨,下旬普降喜雨;南方春雨霏霏,光照不足,不利于农作物生长。 概况 本月有七次冷空气影响我国,除下旬前期一次稍强外,其余均较弱,因此,全国大部份地区气温偏高,月平均气温较常年偏高2—3℃(图1)。中旬,华北、     

北方气温偏高 南方阴雨连绵

本月,全国大部地区气温基本接近常年,三北地区气温持续偏高。西北地区大部、江淮、江南东部、汉水流域、四川盆地降水偏多,南方出现低温阴雨天气,个别省份遭雷雨大风袭击。今年第1号热带风暴于14日生成于西北太平洋上。     

北方少雨干旱 南方阴雨连绵

本月北方少雨雪,大部地区持续干旱;南方雨水偏多,华南阴雨多,气温低,对早稻播种不利;自中旬起,全国大部地区气温偏低。 天气综述 2月5—11日,15—20日,先后有两次较强冷空气侵入我国,以后一次影响较大,使北方地区中     

北方风沙肆虐南方雨水丰沛——2006年4月

2006年4月,全国平均气温比常年同期偏高,全国平均降水量接近常年同期。月内,冷空气活动频繁,我国北方地区共出现了7次沙尘天气过程,其中有3次强沙尘暴过程;全国共出现了5次强降水过程,江淮、江南等地的部分地区出现了暴雨或大暴雨;华北北部和东部、西北地区东北部以及内蒙古中部、云南北部等地的干旱持续或发展。     

北方喜降雨雪 南方阴雨连绵

月内,冷空气活动次数多,我国东部地区气温偏低;北方冬麦区喜降几场春雨雪,旱情缓解;上旬,江淮地区出现今年首场暴雨,淮河水系出现春汛;江南持续低温阴雨天气,对早稻育秧和播种不利。月内有2个热带风暴生成。     

北方风沙肆虐南方雾雨连绵——2004年2月

2月份,冷空气活动较为频繁,我国北方地区多大风天气,出现了三次明显的沙尘天气过程。月内气温变幅较大,全国大部地区月平均气温偏高。华北东部和东北地区降水量显著偏多,东部地区大雾天气频繁。1　天气概况本月主要的降水区位于江南和华南,月降水量一般在50mm以上,其中湖南中部、江西中北部、浙江西部和福建西北部等地的部分地区降水量有1 0 0～1 50mm。全国其余大部地区降水量均不足2 5mm ,其中内蒙古中西部、甘肃西北部、宁夏北部、新疆南部、青海西部、西藏西部和云南西南部的部分地区基本无降水。与常年同期相比(图1 ) ,内蒙古中西部、…     

北方风少雨多 南方阴雨连绵

月内,影响我国的强冷空气次数少,多为小股冷空气活动,我国北方风少雨多,南方阴雨连绵。 月内有一个热带风暴生成。 天气概况 月内,影响我国的冷空气强度比常年同     

2001年4月19～20日大暴雨过程分析

从天气形势、卫星云图、物理量等方面对2001年4月19～20日大暴雨过程进行了分析,总结出这次暴雨的地面和850hPa一些特性。     

"2001.4.6"宁夏沙尘暴过程卫星图像分析

利用日本GMS-5地球同步气象卫星资料,结合常规气象资料,对2001年4月6日发生于宁夏的一次沙尘暴天气过程的影响系统、物理机制、运动学特征、发展演变过程和地形作用等进行了分析。结果表明：在GMS卫星图像上,这次过程有明显的特征,通过图像处理可以得到更多的细节信息。结合实测资料的分析表明：这次沙尘暴天气是高空强西北气流和地面急行冷锋共同影响的天气过程,在卫星云图上其热力与动力过程有明显的反映,而且随着时间的变化其作用不同。三种不同的地形在这次过程中具有不同的效应。这些结果对深入认识沙尘暴天气过程,提高监测预报能力有重要意义。     

吐鲁番2001年4月7～8日特强沙尘暴天气分析

对吐鲁番2001年4月7～8日出现的特强沙尘暴天气进行了分析,指出强锋区、地面冷锋是强沙尘暴形成的大尺度天气背景,高空急流和槽前正涡度平流提供了动力条件,低层强辐合上升运动和大气热力不稳定激发了沙尘暴的形成,沙化的地表是形成这场沙尘暴的重要条件。     

北方地区降水偏少旱情持续降温幅度大局部地区有冻害

4月份，全国大部地区气温正常，但月内变化起伏较大，局部地区出现冷（冻）害，对农作物和果树等的生长发育不利。北方大部降水偏少且大风扬沙天气频繁，部分地区干旱发生或发展，给在田作物和春播生产带来不利影响；南方大部降水接近常年，局部地区降水偏多，出现内涝。南方局部地区还遭到雷雨大风、冰雹等强对流天气袭击，并给当地农业生产和人民生命财产造成一定损失。 1 部分地区降水偏少，旱情持续     

Gearing up for IPCC-2001

The Intergovernmental Panel on Climate Change, the IPCC, is charged withproviding scientific reviews of the current status of the climate sciences.Previous reviews were made in 1990 and 1995 (Houghton et al., 1990, 1995). Thenext review is due out in 2001. One of the important missions of the IPCCis to provide to the scientific community the standard scientific reference for the science of climate change (cf. the Back Cover of the IPCC-95Assessment (Houghton et al., 1995)). This paper discusses flaws in the IPCC-90and the IPCC-95 scientific assessments that seriously compromised thisobjective. The previous reports contained numerous such flaws andrepresentative examples are discussed in detail where the quality of thepresentation was degraded, or even in some instances rendered meaningless byfailures to provide accurate or full error assignments, the sources forresults, the units or quantities being displayed in graphs, the methods usedto calculate results, and access to back-up materials required to understandthe materials being presented. Taken on their own, such errors might, perhaps, be regarded as minor blemishes, but taken in sum and coupled with problems ofpresentation they combine to confuse and to render unconvincing the argumentsbeing presented. In every case the problems described could have been avoided by following the italicized recommendations made throughout the text. It isconcluded that the quality and credibility of future IPCC assessments wouldbe substantially enhanced by adherence to these recommendations.     

Interdecadal variation of April mean rainfall in Korea

The statistical change-point analysis demonstrates that there is a climate regime shift in the April mean precipitation in Korea in 1981. The April mean precipitation in the years post-1981 showed a distinct decrease compared to the years pre-1981. This phenomenon was also noticed in China and Japan, excluding south China. One of the major causes for this decrease in April mean precipitation was the increased snow depth in the mid-latitude regions of continental East Asia. This resulted in a strengthened cold and dry anticyclone anomaly over continental East Asia and a relatively weakened subtropical anticyclone anomaly over the western North Pacific, thus forcing a continuation of the typical winter pressure pattern of “high-West and low-East” in East Asia in April. The strengthened northerly anomaly from this zonal pressure pattern anomaly played a significant role in restricting the northern movement of the subtropical anticyclone and preventing the inflow of warm and humid air into Korea.

     

The Summer Arctic Boundary Layer during the Arctic Ocean Experiment 2001 (AOE-2001)

Boundary-layer measurements made from the Swedish icebreaker Oden during the Arctic Ocean Experiment 2001 (AOE-2001) are analysed. They refer mainly to ice drift in the central Arctic during the period 2–21 August 2001. On board Oden a remote sensing array with a wind profiler, cloud radar and a scanning microwave radiometer, and a regular weather station operated continuously; soundings were also released during research stations. Turbulence and profile measurements on an 18-m mast were deployed on the ice, along with two sodar systems, a microbarograph array and a tethered sounding system. Surface flux and meteorological stations were also deployed on nearby ice floes. There is a clear diurnal cycle in radiation and also in wind speed, cloud base and visibility. It is absent in temperature and humidity, probably due to the very strong control by melting/ freezing ice and snow. In the advection of warm air, latent heat of melting maintains the surface temperature at 0 °C, while with a negative energy balance the latent heat of freezing of the salty ocean water acts to maintain the surface temperature > −2 °C. The constant presence of water at the surface maintains a relative humidity close to 100%, and this is also often facilitated by an increasing specific humidity through the capping inversion, making entrainment a moisture source. This ensures cloudy conditions, with low cloud and fog prevailing most of the time. Intrusions of warm and moist air from beyond the ice edge are frequent, but the local Arctic boundary layer remains at a relatively constant temperature, and is shallow and well mixed with strong capping inversions. Power spectra of surface-layer wind speed sometimes show large variance at low frequency. A scanning radiometer provides a monitoring of the vertical thermal structure with a spatial and temporal resolution not seen before in the Arctic. There are often two inversions, an elevated main inversion and a weak surface inversion, and occasionally additional inversions occur. Enhanced entrainment across the main inversion appears to occur during frontal passages. Variance of the scanning radiometer temperatures occurs in large pulses rather than varying smoothly, and the height to the maximum variance appears to be a reasonable proxy for the boundary-layer depth.     

2014年4月大气环流和天气分析

2014年4月大气环流特征为,北半球极涡呈单极型分布,中心位于喀拉海北端附近;亚洲大陆东部高压脊强度偏强,导致4月我国气温较常年同期(11.0℃)偏高1.1℃,为1961年同期以来第五高值。东亚大槽强度和位置、南支系统和西北太平洋副热带高压接近常年平均状况。4月全国平均降水量为43.7 mm,比常年同期略偏少。月内,江南南部和华南等地出现短时强降水、雷雨大风等强对流天气;北方地区出现多次沙尘天气过程;此外,部分站次出现极端高温、极端降温事件。