珠穆朗玛峰北坡绒布冰川表面辐射特征观测研究

在资料比较稀少的偏远山地冰川进行地面综合气象观测对于研究冰川变化极其重要.珠穆朗玛峰(27.98°N,86.92°E,海拔8844.43 m)地区位于青藏高原南部边缘喜马拉雅山脉中段,自然地理条件独特,环境脆弱,是气候变化和环境变迁的敏感区,同时也是现代冰川作用中心.2005年5-7月和2007年10月-2008年1月在珠穆朗玛峰北坡东绒布冰川积累区(28°01'N,86°57'E,海拔6560 m)开展了综合气象观测研究.分析表明,在东绒布冰川积累区春末夏初月平均气温从5月的-11.3℃上升到7月的-3.4℃,秋冬季月平均气温则从10月的-11.3℃下降到次年1月的-19.0℃.秋冬季主要受西风气流影响,盛行西风或西北风,而且风速较大,1月最大风速达到35 m/s;而在印度季风爆发后主要以南风或西南风为主,风速相对较小.由于海拔高、冰雪面与云之间的多重反射以及复杂地形影响导致地面总辐射较大.春末夏初和秋冬季总辐射平均值分别达到635和502 W/m2.尤其造成5-6月正午前后10 min短波辐射平均值发生超太阳常数的现象比较频繁,最长持续时间接近3 h.晴天由于周围地形作用可使地面总辐射增加140-310 W/m2,约占短波辐射的10%-23%.春末夏初和秋冬季平均反射率分别为0.72和0.69.云和空气湿度对大气长波辐射的影响比较显著,导致大气长波辐射同样具有日变化特征.在地表辐射平衡中云对地面净辐射起负效应.除在秋冬季阴天日平均净辐射为负值外,其余时间均为正值,说明净辐射是地表能量的主要来源.     

西风季风协同作用对云南春末5月降水的影响

基于CN05.1降水资料和ERA5再分析资料,采用多种统计方法对1961~2020年云南春末5月降水的时空变化特征和环流形势进行了分析,并利用西风季风协同指数讨论了西风季风协同作用对云南春末5月降水的影响。结果表明:云南5月降水是春季各月降水量最多月份,其空间上主要表现出自南向北减少的特征。此外,云南5月降水还存在明显的年际变化,但在空间上其气候趋势并不显著。相对于单一西风指数和季风指数,西风季风协同指数对云南5月降水具有更好的指示性,二者之间的相关性以及协同指数与极端降水间的同号率更高。环流场合成分析也表明,当西风季风协同作用增强（减弱）时,受阿拉伯海异常高（低）压影响,云南上空气流以辐散（辐合）为主,有利于上升（下沉）运动,而中低层孟加拉湾主要为异常的气旋（反气旋）控制,促进（抑制）西南水汽向云南输送,造成降水偏多（偏少）。      

惠东高潭三次极端强降水过程成因对比分析

基于ECMWF的ERA-Interim全球大气再分析资料、MICAPS实况数据和广东省气象观测资料,对比分析了广东惠东高潭1979年、2013年和2018年的三次极端强降水过程的成因。结果表明:造成高潭极端强降水的影响系统有台风本体环流、登陆后的台风残余环流、季风低压外围环流等,其中2018年季风低压影响过程降水量最大;不同过程对流层低层强迫暖湿气流辐合抬升方式不同,分别为冷暖气流相互作用、西南季风和偏南季风地交汇、季风涌、边界层急流等;各过程中伴随的低空西南气流和偏南气流的风速大小差异明显,2013年台风残余环流影响时低空西南(偏南)风风速最大。相同点有:影响天气系统移动缓慢,并长时间维持,为极端强降水的发生发展和维持提供有利的动力条件;西南(偏南)季风、边界层急流或西南气流源源不断的水汽输送,为极端强降水的发展和维持提供了充足的水汽条件,同时低空暖湿气流的输送使得暴雨区大气层结不稳定状态长时间维持,利于持续性强降水的发展。研究结论可为今后高潭及其附近地区极端强降水的预报和决策服务提供理论支撑。      

珠峰绒布河谷近地面层气象要素及湍流通量变化

利用2006年5～6月和2007年5～6月中国科学院HEST大气科学实验在珠峰绒布寺河谷野外观测期间获得的观测资料,分析了珠峰地区河谷近地层风向、风速、温度、湿度和CO2的日变化特征,讨论了珠峰北坡冰川风和山谷风的特点以及高原地表辐射、地表反照率和近地层湍流通量的变化特征.结果表明:在复杂地形和特殊下垫面影响下,珠峰绒布河谷地区近地面层各个气象要素和湍流通量日变化特征显著,并且明显存在冰川风和山谷风复合的局地环流,冰川风对该地区地气间物质能量交换起着重要作用.     

2005年南海夏季风建立偏晚和持续异常偏南的成因分析

通过分析大气环流及其热力结构演变特征,揭示2005年春末夏初南海季风爆发偏迟和持续异常偏南的原因。结果表明,阿拉伯高压偏强,与中高纬度高压脊叠加,导致较高纬度冷空气南下青藏高原南侧及中南半岛一带,抑制了中南半岛附近地区大气增温,不利于南海季风的爆发;索马里急流及赤道西风建立偏晚使中南半岛对流凝结潜热偏弱,是中南半岛一带大气增温偏迟的另一重要原因。6月上中旬,印度半岛北部冷空气势力偏强,大气增温缓慢,使印度季风和亚洲南部季风槽向北推进迟缓,使强劲的西南季风径直向东输送进入南海,有利于南海西南季风长期持续偏南。春末青藏高原积雪偏多,积雪融化抑制了地面增温和大气感热加热,是南海季风爆发偏晚的另一重要原因。6月上中旬,西南季风北上偏迟导致高原对流偏弱,热源偏弱,负反馈作用抑制了西南季风进一步北上,导致西南季风持续异常偏南。     

大理地区对流层至低平流层大气垂直结构的特征分析

利用JICA计划中日合作"2008年季风过程与暴雨天气上游关键区综合气象观测试验"期间在大理站的GPS探空资料,分析了季风3个加密观测阶段该地区对流层至低平流层大气垂直结构特征。结果表明,观测期间对流层顶以第二(副热带)对流层顶为主,平均高度为14.8 km,对流层平均温度递减率为6.4℃·km~(-1);对流层顶高度与气温、气压和风速均呈显著的负相关;季风爆发前(后)水汽主要集中在6.6(8.3)km以下对流层;季风爆发前对流层至低平流层被西风带控制;季风爆发阶段对流层至低平流层风速减小,低平流层风向由西风转成东风;季风强盛阶段低平流层东风逐渐下传,对流层高层至低平流层风速增大,风向基本转成偏东风。     

贵州东部中亚热带季风湿润区柑气候区划

利用贵州省东部34个站点1981-2005年逐年的年平均气温、降水量、日照时数、≥10℃积温、极端最低气温、≥35℃极端最高气温出现的天数、1月和7月的月平均气温、4月中旬至5月中旬和7月中旬至11月中旬的积温和降水量以及4-10月降水量、3-5月和7-10月的日照时数共15个气候变量进行经验正交函数分解,确定柑气候区划指标,应用模糊聚类分析,将贵州省东部中亚热带季风湿润区划分为4种不同类型的柑气候区,其结果指出了贵州东部柑生产布局中的问题,为贵州甚至西南地区柑产业基地建设提供了科学依据.     

菲律宾的气候

菲律宾是一个热带岛国,它位于约14.7°—21.5°N之间的热带地区,全年中太阳两次直射地面,太阳辐射热量极为丰富。全年气温都较高,以首都马尼拉为例,年平均气温为26.7℃,最热月平均气温28.6℃,约与我国东南沿海盛夏相仿;最冷月平均气温也达到25.0℃,比我国沈阳地区盛夏7月平均气温还要高些。平均年较差仅3.6℃,所以无春夏秋冬之分。 菲律宾最冷月和我国一样,出现在1月,但最热月却不在7、8月,而出现在多雨季节来临前的5月。这与菲律宾地区的季风进退有关。菲律宾及其附近海域6—9月盛行西南季风,带来丰沛、的降水,所以气温相对下降;10月到次年5月,盛行东北季风,相对干燥少雨,随着太阳入射角的增高,最热月便出现在5月。     

2013年7月大气环流和天气分析

2013年7月环流特征如下:欧亚中高纬呈西低东高异常分布型,我国中高纬多短波槽活动,西太平洋副高强度较常年偏强,西南季风较常年偏强。7月全国平均降水量138.9 mm,较常年同期（120.6 mm）偏多15.2%,为1951年以来第四多雨年;全国平均气温为22.4℃,较常年同期（21.9℃）偏高0.5℃。月内共出现11次强降水过程,多站出现极端日降水量。7月共有4个热带气旋在南海和西北太平洋活动,并有“温比亚”、“苏力”、“西马仑”等3个热带气旋登陆。江南、江淮、江汉及重庆等地出现持续高温天气,全国100个气象观测站发生极端高温事件。     

基于逐时资料的黄山雾凇特征及气象条件分析

利用2004—2016年黄山气象站逐日、逐时地面气象观测资料分析了雾凇的时间分布特征及气象条件。结果表明:(1)黄山年平均雾凇日61.6d,年份之间差异明显;雾凇初日主要在11月,终日主要在3—4月;连续雾凇日数多在3～4d,占40%,各年均出现了连续雾凇日数≥10d的情况。(2)雾凇出现在10月至次年4月,其中12月至次年3月雾凇日数占89.8%;月平均雾凇日数与月平均气温呈显著负相关。雾凇还存在一定的日变化,08:00—09:00最多,18:00最少。(3)逐日资料统计表明,适宜雾凇出现的气象条件是雾日且日平均气温在-8～2℃之间、平均相对湿度≥80%、平均风速2～9m/s。(4)逐时资料统计表明,雾凇的形成主要受气温影响,雾凇形成前需7h以上的累计低温(≤0℃),适宜雾凇形成的气象条件是有雾且气温在-6～1℃之间,湿度≥95%,风速2～11m/s,较好地反映了雾凇形成的临界气象条件。     

Meteorological responses to Mt. Baekdu volcanic eruption over east asia in an offline global climate-chemistry model: A pilot study

We examine the meteorological responses due to the probable eruption of Mt. Baekdu using an off-line Climate-Chemistry model that is composed of the National Center for Atmospheric Research (NCAR) Climate Atmosphere Model version 3 (CAM3) and a global chemistry transport model (GEOS-Chem). Using the aerosol dataset from the GEOS-Chem driven by GEOS-5 meteorology, experiment and control simulations of the climate model are performed and their meteorological differences between the two simulations are analyzed. The magnitudes of volcanic eruption and column injection height were presumably set to 1/200 of the Mt. Pinatubo eruption and 9 km, respectively. Significant temperature drop in the lower troposphere (850 hPa), which is mainly due to a direct effect of prescribed volcanic aerosols from Mt. Baekdu, has been simulated up to about ?4 K. The upper atmosphere (150 hPa) right above the volcano, however, shows significant warming due to the absorption of the infrared radiation by volcanic aerosols. As a result of the volcanic eruption in the climate model, wave-like patterns are shown in both the geopotential height and horizontal wind. The changes in the lower atmospheric temperature are well associated with the modification of the atmospheric circulation through the hydrostatic balance. In spite of limitations in our current simulations due to several underlying assumptions, our results could give a clue to understanding the meteorological impacts from Mt. Baekdu eruptions that are currently attracting considerable public attention.     

Earth Summit Mission 2022: Scientific Expedition and Research on Mt. Qomolangma Helps Reveal the Synergy between Westerly Winds and Monsoon and the Resulting Climatic and Environmental Effects

“Earth summit mission 2022” is one of the landmark scientific research activities of the Second Tibetan Plateau Scientific Expedition and Research(STEP). This scientific expedition firstly used advanced technology and methods to detect vertical meteorological elements and produce forecasts for mountain climbing. The “Earth summit mission 2022”Qomolangma scientific expedition exceeded an altitude of over 8000 meters for the first time and carried out a comprehensive scientific investigation missi...     

Seasonal Characteristics of Surface Radiation Fluxes on the East Rongbuk Glacier in the Mt.Everest Region

Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005(the spring-summer period),and from 2 October 2007 to 20 January 2008(the autumn-winter period),surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station(AWS).The...     

Modeling of Regional High Ozone Episode Observed at Two Mountain Sites (Mt. Tai and Huang) in East China

A high O₃ episode was observed during 23–25 May 2004 at two high-mountain sites reflecting the regional pattern of air pollutants over East China. This episode lasted about three days with the maximum hourly O₃ mixing ratios reaching 111 and 114 ppbv at Mt. Tai and Huang, respectively. Backward trajectories and meteorological analysis indicated that regional transport, associated with a weak high pressure system over the East China Sea, might play an important role in the formation of this high ozone episode. The nested air quality prediction modeling system (NAQPMS) was applied to investigate the formation and evolution of this high O₃ event. The comparison of model results with observations showed that NAQPMS successfully reproduced the main observed patterns of O₃ and meteorological parameters during the simulated period. The model results with emission over the Yangtze Delta and the East Central China switched on/off clearly showed that ozone and its precursors transported from the Yangtze Delta and the East Central China enhanced the high ozone episode at two sites, with a contribution of 20%–50% during the episode. In addition, based on process analysis with the model, chemical production and regional transport appeared to be the main causes of high ozone episode involving a large amount of high-ozone air masses and precursors transported from the surrounding areas. The horizontal transport is more active during the period of high ozone episode than that during the non-episode at Mt. Tai as well as Mt. Huang.     

中国西部大气清洁地区黑碳气溶胶的观测研究

黑碳气溶胶是大气气溶胶中的重要成分,对可见光和红外光都具有强烈吸收作用,对气溶胶的局地及全球的气候效应有重要的贡献。本文给出了1994年7月到1995年底在瓦里关本底台进行的黑碳气溶胶观测结果,结合气象观测资料以及在我国东部地区的部分观测结果对该地区大气中的黑碳气溶胶浓度及其变化特点进行了讨论分析。瓦里关山地区的大气黑碳气溶胶月平均浓度为130～300 ng/m3,大大低于我国东部地区;该地区大气中黑碳气溶胶浓度的变化明显地与来自工业及人口集中地区的污染气团的影响有关,不同风向时的黑碳气溶胶浓度水平有明显的差异;由最大出现频数统计分析得出该地区大气黑碳气溶胶的本底浓度范围为50～120 ng/m3;冬季该地区大气黑碳气溶胶的平均浓度和本底浓度都较低,而春季较高。     

Seasonal Characteristics of Surface Radiation Fluxes on the East Rongbuk Glacier in the Mt. Everest Region

Ground-based measurements are essential for understanding alpine glacier dynamics, especially in remote regions where in-situ measurements are extremely limited. From 1 May to 22 July 2005 (the spring-summer period), and from 2 October 2007 to 20 January 2008 (the autumn-winter period), surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l. by using an automatic weather station (AWS). The results show that surface meteorological and radiative characteristics were controlled by two major synoptic circulation regimes: the southwesterly Indian monsoon regime in summer and the westerlies in winter. At the AWS site on the East Rongbuk Glacier, north or northwest winds prevailed with high wind speed (up to 35 m s-1 in January) in winter while south or southeast winds predominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer. Intensity of incoming shortwave radiation was extremely high due to the high elevation, multiple reflections between the snow/ice surface and clouds, and the high reflective surrounding surface. These factors also caused the observed 10-min mean solar radiation fluxes around local noon to be frequently higher than the solar constant from May to July 2005. The mean surface albedo ranged from 0.72 during the spring-summer period to 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was greatly affected by the cloud condition and atmospheric moisture content. The overall impact of clouds on the net all-wave radiation balance was negative in the Mt. Qomolangma region. The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except for a few overcast days. On monthly basis, the net all-wave radiation was always positive.     

区域站和基准站气溶胶的分析

文章讨论了秋季（1994年10月）和冬季（1995年1月）在中国西部青海省共和县瓦里关山（36°17′N，100°54′E，海拔3816 m）基准站和中国东北黑龙江省五常县的龙凤山（44°44′N，127°36′E，海拔331 m）及中国东南沿海的浙江省临安县的横畈乡（30°18′N，119°44′E，海拔131 m）两个区域本底站（上述3站均属WMO）所采集的气溶胶样品的质量浓度、可溶性离子浓度的时空分布特征和变化规律。初步得出:气溶胶质量浓度和可溶性离子浓度以临安为最高。其次是龙凤山，而瓦里关山为最低     

Investigating the implications of meteorological indicators of seasonal rainfall performance on maize yield in a rain-fed agricultural system: case study of Mt. Darwin District in Zimbabwe

The study focuses on the impacts of climate variability and change on maize yield in Mt. Darwin District. The rainfall and temperature data for the period under study that is from 1992 to 2012 were obtained from Meteorological Services Department of Zimbabwe at daily resolution while crop yield data were obtained from Department of Agricultural, Technical and Extension Services (AGRITEX) and Zimbabwe Statistics Agency (ZIMSTAT) at seasonal/yearly resolution. In order to capture full rainfall seasons, a year was set to begin on 1 June and end on 31 July the next year. Yearly yield, temperature and rainfall data were used to compute time series analysis of rainfall, temperature and yield. The relationship between temperature, rainfall, quality of season (start, cessation, dry days, wet days and length) and yield was also investigated. The study also investigated the link between meteorological normal and maize yield. The study revealed that temperature is rising while rainfall is decreasing with time hence increasing risk of low maize yield in Mt. Darwin. Correlation between maize yield was higher using a non-linear (R ² = 0.630) than a linear regression model (R ² = 0.173). There was a very high correlation between maize yield and number of dry days (R = −0.905) as well as between maize yield and length of season (R = 0.777). We also observed a strong correlation between percentage normal rainfall and percentage normal maize yield (R ² = 0.753). This was also agreed between rainfall tessiles and maize yield tessiles as 50 % of the seasons had normal and above normal rainfall coinciding with normal and above normal maize yield. Of the 21 seasons considered, only one season had above normal rainfall while maize yield was below normal. The study concluded that there is a strong association between meteorological normal and maize yield in a rain-fed agricultural system. Climate information remains crucial to agricultural productivity hence the need to train farmers to access the information and use it for the benefit of their activities.

     

New evidence of orographic precipitation suppression by aerosols in central China

The correlation between light precipitation events and visibility at Mt. Hua, (Shannxi Province, China) and at the surrounding plains stations was analyzed. Trends and changes in visibility, precipitation, the precipitation difference between Mt. Hua and the plains stations (De) and wind speed over the study area during the years 1980–2009 were also investigated. The significant positive correlation between visibility and light precipitation throughout the study period indicates that light precipitation events, notably orographic precipitation, are suppressed by aerosol pollution in this region. The trend of increasing air pollution aerosols since 1980, represented by visibility at Mt. Hua, ended in 2002 with a decreasing trend observed in more recent years. These changes were mirrored by corresponding changes in De. However, the total precipitation trends at Mt. Hua and the plains stations are consistent in both frequency and amount during the two periods, suggesting that the suppressive effect of pollution aerosols on light and moderate precipitation is the most likely cause for the changes in orographic precipitation at Mt. Hua during this time. The analysis of wind strength suggests that the increase in winds at Mt. Hua is highly related to the aerosol radiative effects; this increase of mountain winds is therefore a potential cause for the reduction in precipitation at Mt. Hua. This research provides further support for the hypothesis that aerosol microphysical effects can reduce orographic precipitation and suggests that aerosol radiative effects might act to suppress orographic precipitation through changes in wind speed.     

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island,Greece

Crete Island is located in the southmost border of East Mediterranean basin, facing exacerbating atmospheric conditions (mainly concentrations of particulates) due to Saharan dust outbreaks. It is worth to note that these episodes are more frequent during spring and autumn, when mild biometeorological conditions become intolerable due to the synergy of the so called Föhn winds. Cretan mountains, especially Psiloritis Mt. (summit at 2456 m), are orientated perpendicularly to the southwest air mass flow, generating the Föhn winds. Propagating from the leeward of the mountains, these dry, hot winds have an effect on prevailing biometeorological conditions. While descending to the lowlands on the leeward side of the range, the wind becomes strong, gusty, and desiccating. This wind often lasts less than an hour to several days, with gradual weakening after the first or the second day. Sometimes, it stops very abruptly. In this work, the authors examined and analyzed the abrupt changes of human thermal perception within specific case studies during which Föhn winds appeared in Heraklion city at the leeward of Psiloritis Mt, associated with extreme Saharan dust episodes, observed within the period 2006–2010. In order to verify the development of Föhn winds, Meteorological Terminal Aviation Routine Weather Reports (METARs, meteorological observations every half hour), were acquired from the Heraklion meteorological station installed by the Hellenic National Meteorological Service (HNMS). The biometeorological conditions analyzed are based on human thermal bioclimatic indices such as the Physiologically equivalent temperature (PET) and the Universal Thermal Climate Index (UTCI). METAR recordings of meteorological variables, such as air temperature, vapor pressure, wind speed, and cloudiness, were used as input variables in modeling the aforementioned thermal indices, so that to interpret the grade of the thermo-physiological stress. The PET and UTCI analysis was performed by the use of the radiation and bioclimate model, “RayMan,” which is well-suited to calculate radiation fluxes and human biometeorological indices. The results of the performed analysis showed even an increase of air temperature from 20 to 30 °C within 5 h, associated with a decrease in the vapor pressure from 11.5 to 9.3 hPa. In addition, the wind speed at 10 m increased from 5.1 to 20.1 m/s, 3.7 to 14.3 m/s with respect to 1.1 m height, during the events of Föhn winds. The biometeorological analysis has given evidence that slight/moderate heat stress classes of the examined thermal indices appear during Saharan dust episodes. Such conditions are uncommon at the beginning of spring season, indicating that Saharan dust episodes are not only responsible for acute health impacts but also for adverse biometeorological conditions, due to the very likely development of Föhn winds towards the wider area of Heraklion, a coastal city in the eastern Mediterranean.