气象学报
氣象學報
기상학보
ACTA METEOROLOGICA SINICA
2014年
2期
402-416
,共15页
94GHz 测云雷达%回波特征%云物理特性%0℃层暗带
94GHz 測雲雷達%迴波特徵%雲物理特性%0℃層暗帶
94GHz 측운뢰체%회파특정%운물리특성%0℃층암대
94 GHz cloud radars%Echo characteristics%Physical properties of clouds%Dim bands
重点利用英国的94 GHz Galileo 测云雷达,结合35 GHz 云雷达、地面雨滴谱仪、雨量计和探空资料等,分析了94 GHz 雷达的回波特征及测云能力。结果表明:(1)94 GHz 云雷达能清楚反映出云及弱降水过程的云系结构变化和云内小尺度变化,可以探测到雾,雾的多普勒速度杂乱;(2)94 GHz 云雷达区别于厘米波雷达的较显著的回波特征是层状云降水的0℃层亮带下面雷达反射率因子降低不明显或没有降低及0℃层亮带上面存在0℃层暗带,分别是因为雨滴较大及冰晶较大产生非瑞利散射引起的,暗带区域的宽度一般在600 m 以下,暗带区域的许多冰晶聚合物最大尺度可超过3 mm,有些暗带区域的许多冰晶聚合物最大尺度可超过6.8 mm,多普勒速度及谱宽显著增大的地方是融化层顶;(3)与35 GHz 测云雷达相比,由于衰减和非瑞利散射,降水时的94 GHz 雷达反射率因子远小于35 GHz 雷达反射率因子,使探测到的高云云顶高度偏低,但94 GHz 云雷达抑制地物杂波的能力更高,在晴空低云探测方面具有优势。这些结果为中国正在研制的94 GHz 云雷达回波可靠性分析提供了参考。94 GHz 云雷达与其他探测手段结合,可揭示各种天气形成的物理机制,对天气预报、云物理的发展、人工影响天气、气候变化的研究均有重要意义。
重點利用英國的94 GHz Galileo 測雲雷達,結閤35 GHz 雲雷達、地麵雨滴譜儀、雨量計和探空資料等,分析瞭94 GHz 雷達的迴波特徵及測雲能力。結果錶明:(1)94 GHz 雲雷達能清楚反映齣雲及弱降水過程的雲繫結構變化和雲內小呎度變化,可以探測到霧,霧的多普勒速度雜亂;(2)94 GHz 雲雷達區彆于釐米波雷達的較顯著的迴波特徵是層狀雲降水的0℃層亮帶下麵雷達反射率因子降低不明顯或沒有降低及0℃層亮帶上麵存在0℃層暗帶,分彆是因為雨滴較大及冰晶較大產生非瑞利散射引起的,暗帶區域的寬度一般在600 m 以下,暗帶區域的許多冰晶聚閤物最大呎度可超過3 mm,有些暗帶區域的許多冰晶聚閤物最大呎度可超過6.8 mm,多普勒速度及譜寬顯著增大的地方是融化層頂;(3)與35 GHz 測雲雷達相比,由于衰減和非瑞利散射,降水時的94 GHz 雷達反射率因子遠小于35 GHz 雷達反射率因子,使探測到的高雲雲頂高度偏低,但94 GHz 雲雷達抑製地物雜波的能力更高,在晴空低雲探測方麵具有優勢。這些結果為中國正在研製的94 GHz 雲雷達迴波可靠性分析提供瞭參攷。94 GHz 雲雷達與其他探測手段結閤,可揭示各種天氣形成的物理機製,對天氣預報、雲物理的髮展、人工影響天氣、氣候變化的研究均有重要意義。
중점이용영국적94 GHz Galileo 측운뢰체,결합35 GHz 운뢰체、지면우적보의、우량계화탐공자료등,분석료94 GHz 뢰체적회파특정급측운능력。결과표명:(1)94 GHz 운뢰체능청초반영출운급약강수과정적운계결구변화화운내소척도변화,가이탐측도무,무적다보륵속도잡란;(2)94 GHz 운뢰체구별우전미파뢰체적교현저적회파특정시층상운강수적0℃층량대하면뢰체반사솔인자강저불명현혹몰유강저급0℃층량대상면존재0℃층암대,분별시인위우적교대급빙정교대산생비서리산사인기적,암대구역적관도일반재600 m 이하,암대구역적허다빙정취합물최대척도가초과3 mm,유사암대구역적허다빙정취합물최대척도가초과6.8 mm,다보륵속도급보관현저증대적지방시융화층정;(3)여35 GHz 측운뢰체상비,유우쇠감화비서리산사,강수시적94 GHz 뢰체반사솔인자원소우35 GHz 뢰체반사솔인자,사탐측도적고운운정고도편저,단94 GHz 운뢰체억제지물잡파적능력경고,재청공저운탐측방면구유우세。저사결과위중국정재연제적94 GHz 운뢰체회파가고성분석제공료삼고。94 GHz 운뢰체여기타탐측수단결합,가게시각충천기형성적물리궤제,대천기예보、운물리적발전、인공영향천기、기후변화적연구균유중요의의。
The echo characteristics and capability of the 94 GHz cloud radars of England are analysed by refering to the Galileo radar,35 GHz radar,raindrop disdrometer,rain gauge and sounding data.The results show that (1)94 GHz cloud radars can observe cloud structures of the clouds and weak precipitations,small scale variations in the clouds and fogs,and the positive and negative Doppler velocity of fogs;(2)the significant echo characteristics that distinguish 94 GHz cloud radars from centim-eter wave radars are that the decrease of the radar reflectivity factor at the bottom of bright bands is slight or not and the dim bands which generally are of 600 m width exist above the bright bands,which are caused by non-Rayleigh scattering of bigger rainfall or ice crystal with the maximum size of aggregates able to be more than 3 mm in dim bands and even more than 6.8 mm in some dim bands,and the significant increase of Doppler velocity and spectral width implying the top of melting layer;(3) compared with 35 GHz radars,94 GHz cloud radars may underestimate the top height of high clouds and the reflectivity factor of 94 GHz cloud radars is weaker than that of 35 GHz radars due to the signals attenuation and non-Rayleigh scattering of 94 GHz cloud radars,but 94 GHz cloud radars can filter the ground clutter and detect low clouds.The results can provide a reference for reliability analysis of 94 GHz cloud radar echoes in China.Combining with the other detection methods,94 GHz cloud radars can reveal physical mechanism for all kinds of weather,which are of important significance in researches on weath-er forecast,investigation into cloud physics,weather modification and climate change.