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641.
The paper presents data on flux variations of ionizing EUV radiation for wavelengths shorter than 130 nm and in L-alpha hydrogen line on the basis of measurements performed on-board a Russian Earth-orbiting and interplanetary spacecrafts in the period since 1978 to 1997. These data were received by using common heritage instrumentation installed on four PROGNOZ satellites, INTERBALL-1, PHOBOS, and the geosynchronous meteorological satellite ELECTRO. Though the time series of observations is not continuous, it gives a possibility to estimate flux variations in certain periods of time and during 11–year cycle. During quiet periods of solar activity (except for flares) a level of diurnal variations is rather low, it being equal to about 3%. Radiation changes in L-alpha line from maximum to minimum in an 11–year cycle of solar activity achieves 200% and increases in the range of short waves. Data measured onboard the Russian satellites are compared with data obtained by Solar Mesospheric Explorer. 相似文献
642.
Calculation of lava effusion rates from Landsat TM data 总被引:1,自引:0,他引:1
Andrew J. L. Harris Luke P. Flynn Laszlo Keszthelyi Peter J. Mouginis-Mark Scott K. Rowland Joseph A. Resing 《Bulletin of Volcanology》1998,60(1):52-71
We present a thermal model to calculate the total thermal flux for lava flowing in tubes, on the surface, or under shallow
water. Once defined, we use the total thermal flux to estimate effusion rates for active flows at Kilauea, Hawaii, on two
dates. Input parameters were derived from Landsat Thematic Mapper (TM), field and laboratory measurements. Using these parameters
we obtain effusion rates of 1.76±0.57 and 0.78±0.27 m3 s–1 on 23 July and 11 October 1991, respectively. These rates are corroborated by field measurements of 1.36±0.14 and 0.89±0.09 m3 s–1 for the same dates (Kauahikaua et al. 1996). Using weather satellite (AVHRR) data of lower spatial resolution, we obtain
similar effusion rates for an additional 26 dates between the two TM-derived measurements. We assume that, although total
effusion rates at the source declined over the period, the shut down of the ocean entry meant that effusion rates for the
surface flows alone remained stable. Such synergetic use of remotely sensed data provides measurements that can (a) contribute
to monitoring flow-field evolution, and (b) provide reliable numerical data for input into rheological and thermal models.
We look forward to being able to produce estimates for effusion rates using data from high-spatial-resolution sensors in the
earth observing system (EOS) era, such as Landsat 7, the hyperspectral imager, the advanced spaceborne thermal emission spectrometer,
and the advanced land imager.
Received: 25 July 1997 / Accepted: 26 February 1998 相似文献
643.
Plinian式火山喷发柱最大高度定量计算模式探讨 总被引:1,自引:0,他引:1
Plinian式火山喷发柱最大高度是研究火山喷发对环境、气候影响时空范围的重要物理学参数,在分析了影响Plinian式火山喷发柱最大高度诸因素的基础上认为,火山喷发的质量通量是反映火山喷发柱最大高度最有效并且在实际中可以进行测量的参数之一,以此为基础,利用目前实测的火山喷发柱最大高度的数值与火山喷发质量通量的结果,建立两者的相关方程为:H=0.2×M0.28。 相似文献
644.
澜沧—耿马震区构造能流图象研究 总被引:1,自引:0,他引:1
根据澜沧-耿马震区构造能流图象的研究,其结果表明震产生了两条长度分别为42公里、55公里的北西向主破裂,同时产生了几北东-近南北向的次级破裂。通过与宏观资料的对比,可观看出构造能流图象和震害分布具有较好的一致性。 相似文献
645.
646.
热桩与空气间的对流换热规律研究 总被引:3,自引:0,他引:3
通过低温室内试验研究热桩与空气间的对流换热规律结果表明,热桩的热流量和放热系数随气温、风速的变化而变化,但因冷凝器特定外形热阻及热桩内凝结换热的影响,气温大于-12℃和风速大于2m/s时,热桩与空气间的对流换热效率降低。 相似文献
647.
Parameterization of sensible heat and momentum fluxes as inferred from an analysis of tower observations archived during MONTBLEX-90
at Jodhpur is proposed, both in terms of standard exchange coefficientsC
H
andC
D
respectively and also according to free convection scaling. Both coefficients increase rapidly at low winds (the latter more
strongly) and with increasing instability. All the sensible heat flux data at Jodhpur (wind speed at 10 m Ū10 < 8 ms−1) also obey free convection scaling, with the flux proportional to the ‘4/3’ power of an appropriate temperature difference
such as that between 1 and 30 m. Furthermore, for Ū10 < 4 ms−1 the momentum flux displays a linear dependence on wind speed. 相似文献
648.
In this paper, acoustic sounder (sodar) derived vertical velocity variance (σ
w
2
) and inversion height (Z
i) are used to compute the surface heat flux during the convective activity in the morning hours. The surface heat flux computed
by these methods is found to be of the same order of magnitude as that obtained from tower measurements. Inversion heights
derived from sodar reflectivity profiles averaged for an hour are compared with those obtained from the σ
w
2
/Z profile. Variation of σ
w
2
in the mixed layer is discussed. The data were collected during the Monsoon Trough Boundary Layer Experiment 1990 at Kharagpur.
The analysis is made for four days which represent the pre-monsoon, onset, active and relatively weak phases of the summer
monsoon 1990. The interaction of the ABL with the monsoon activity is studied in terms of the variation of inversion height,
vertical velocity variance and surface heat flux as monsoon progresses from June to August. 相似文献
649.
辐散风和瞬变的涡度通量的异常对定常波年际异常的强迫作用 总被引:2,自引:4,他引:2
研究了1982/1983年12—2月对流层上层由辐散风和瞬变的涡度通量所产生的涡度源异常对定常波异常的强迫作用。结果表明,瞬变的涡度通量辐合的异常有抵消或耗散辐散风产生的涡度源异常的趋势;定常波的异常是在这两种强迫力的共同作用下维持的。同时还表明,对1982/1983年的情况,热带和赤道中东太平洋上的涡度源异常以及中纬度北太平洋上的涡度源异常都对太平洋/北美地区的大气环流异常起了重要的作用。 相似文献
650.