祁连山区季节性积雪资源的气候分析^*   总被引：14，自引：0，他引：14  

陈乾  陈添宇 《地理研究》1991,10(1):24-38

本文采用1986年10月至1988年9月NOAA—9、10两颗卫星的AVHRR资料标准化后反演的积雪参量,对照祈连山区26个气象站1951—1988年逐日雪深、雪密度和积雪日数的资科,修正卫星反演的平均值。得到高分辨率多年平均雪深和雪盖频率的空间分布。从而估算出各流域平均雪储量,并与降雪量和春季融雪径流作对此分析。  相似文献   

Type III Bursts Associated with Millisecond Spikes Which Occurred Within the Frequency Range from 230 to 300 MHz     

Ma  Yuan  Xie  Ruixing  Zheng  Xiangming 《Solar physics》2001,200(1-2):157-166

The metric spectral data obtained at the Yunnan Observatory from July 1990 to December 1991 are analysed and some type III bursts associated with millisecond spikes are found. Their different morphologies reveal the relation between the type III bursts and the millisecond spikes. Based on the occurrence time and the characteristics of continuity and changes of the morphologies in the spikes and the type III bursts of two typical events, we verify that the acceleration region of the coronal electrons is located above the emitting region of the millisecond spikes and the type III bursts. The observations show that the interface frequency of a pair of type III bursts lies near 250 MHz. Finally the authors attempt to explain qualitatively the generating mechanism of the metric millisecond spike-type III bursts by means of the plasma hypothesis.  相似文献   

Radio Observations at 232 MHz and Multifrequency Spectral Studies of SNR HB21     

X.Z. Zhang  S.J. Qian  L.A. Higgs  T.L. Landecker  X.J. Wu 《Astrophysics and Space Science》2002,279(4):355-366

Radio observational results at 232 MHz and multifrequency studies of supernova remnant (SNR) HB21 are presented. Its integrated flux density at 232 MHz is about 390 ± 30 Jy. Both the integrated spectral index and the spatial variations of spectral index of the remnant were calculated by combining the new map at 232 MHz with previously published maps made at 408, 1420, 2695, and 4750 MHz. The SNR has an integrated spectral index of about α = -0.43(S _ν ∝ ν^α) between 232 and 4750 MHz. In general the spectral index varies from –0.5 in southeast and west regions of the remnant to –0.3 in the central region and near the northwest edge. The new data of 232 MHz reveals that there is interaction between the remnant and the surrounding gas along the east edge of the remnant which causes the spectrum flattening at low frequency, while the very good agreement between the structure of X-ray emission and the central flat spectrum area suggests that the existence of thermal emission is the reason of spectrum flattening in the area. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

FIRST RECORD OF AN EYE DISEASE IN THE BOWHEAD WHALE (BALAENA MYSTICETUS)     

祝茜 《中国海洋湖沼学报》1997,15(2):192-192

Bowheadwhale(Balaenamysticetus)isahighlyvaluedspecies,andofimportancetotheAlaskancoastEskimoswhoharvestitastheirtraditionalfoodresource.Itisknownastheicewhalebecauseitspendsmuchofitslifeintheice.ItwassurprisingtofindacaseofeyediseaseintheeyespecimensfromthebowheadwhalesharvestedinthecoldenvironmentatBarrow,Alaska,USA.Somebasicinformationispasentedbelow.Bowheadwhale96B14washarvestedbywhalingcaptainJacobAdamsonSeptember16,1996.ThisWhalewasafemalewithbodylengthof8.33m.Thecorneaofbotheyeswas…  相似文献   

PRECIPITATION PATTERNS IN FLOOD SEASON OVER CHINA ASSOCIATED WITH THE EL NI■O/SOUTHERN OSCILIATION     

钱步东 《中国地理科学(英文版)》1997,(3)

I.I~IOXENds(EINabs/SouthernOscillation)eventsaretheintensivesignalsofair-seainteractionintropicalarea.PlentyOfresultsfromdifferentresearchersshoWthattheENdssignalcanbedetectedoninterannualvallationsoflargescaleatmOSPhericcirculationandclimateregimeSovermostpartsoftheworld.SeveralkindsofrelationShipbetweenENdsandprecipitationoverChinahavebeenrevealedbydifferentreSearcherS,buttherearemanydifferencesamongthepublishedreSults.Itmayberesulted*fromthatdifferentreSearchersuseddifferentindic…  相似文献   

双成分星际介质的折射闪烁     

张喜镇 《天文学报》1996,37(4):421-429

本文用比较严格的理论讨论了由连续介质和散射薄屏组成的星际介质对河外射电源的折射闪烁．对折射闪烁引起的流量变化的结构函数Ｄ（τ）（τ为迟后时间）的计算表明，结构函数的幂律部份的指数Ｐ（Ｄ（τ）（∝τＰ）依赖于上述两个成份的相对散射强度，即在连续介质散射为主的情况下；而在薄屏散射为主的情况下；若两个成份的散射可相比较时，１＜Ｐ＜２．因此本模型可以用于解释在河外射电源和脉冲星中观测到的折射闪烁的结构函数具有不同幂指数的情形，特别是Ｐ～１．５的情形．  相似文献   

first record of an eye disease in the bowhead whale ( Balaena mysticetus )     

Zhu Qian 《中国海洋湖沼学报》1997,15(2):192

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MD数字化断层形变测量仪资料的应用分析     

李杰  马玉香 《大地测量与地球动力学》2001,21(4):95-102

分析了“九五”期间安装在“山东数字化地震前兆台网”的MD跨断层形变测量仪资料的干扰因素、变化特点及其与水准、基线观测的一致性 ,探讨了其映震能力及断层运动的表现方式  相似文献   

Multifrequency polarization variations in 0917+624     

S.J. Qian  A. Kraus  T.P. Krichbaum  A. Witzel  J.A. Zensus 《Astrophysics and Space Science》2001,278(1-2):119-122

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Inversion of Vegetation Components Based on the Spectral Mixture Analysis Using Hyperion Data     

Mingchang Wang  Xuefeng Niu  Qian Yang  Shengbo Chen  Guodong Yang  Fengyan Wang 《Journal of the Indian Society of Remote Sensing》2018,46(1):1-8

Hyper spectral remote sensing is widely used to identify ground objects as a result of the advantages of ground radiation intensity characteristics and spectral position characteristics, in which inversion of vegetation components is the difficult point and hotspot. In this study, Huma county of Heilongjiang Province was selected as the study area, the canopy spectra of four types of typical vegetation were measured in situ firstly, including mongolian oak, cotton grass, lespedeza and white birch. Then, on the basis of analyzing the canopy spectral characteristics and their parameterization, the spectral differences of different vegetations were located, and the parameterization method of characteristics identification was determined. Finally, Hyperion data were used to calculate the canopy albedos based on the bidirectional reflectance model of vegetation canopies, and to map the vegetation components in the study area by use of linear spectral mixture model. The results showed that inversion of vegetation components in high vegetation-covered area was accurate using the canopy albedos and liner spectral mixture model, and was identical with the field sampling, which validated the feasibility of canopy albedos and liner spectral mixture model for the inversion of vegetation components.  相似文献