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661.
With a precise geoid, GOCE will allow an estimation of absolute dynamic topography from altimetry. The projected benefits
to operational oceanography and its applications are analyzed herein. After a brief overview of operational oceanography,
we explain how the new geoids will be used in the future to improve real time altimeter products and to better constrain modelling
and data assimilation systems. A significant impact is expected both for mesoscale (e.g. better estimations and forecasts of currents for pollution monitoring, marine safety, offshore industry) and climate (better
initialization of coupled ocean/atmosphere models) applications.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
662.
Neugebauer M. Steinberg J.T. Tokar R.L. Barraclough B.L. Dors E.E. Wiens R.C. Gingerich D.E. Luckey D. Whiteaker D.B. 《Space Science Reviews》2003,105(3-4):661-679
Some of the objectives of the Genesis mission require the separate collection of solar wind originating in different types
of solar sources. Measurements of the solar wind protons, alpha particles, and electrons are used on-board the spacecraft
to determine whether the solar-wind source is most likely a coronal hole, interstream flow, or a coronal mass ejection. A
simple fuzzy logic scheme operating on measurements of the proton temperature, the alpha-particle abundance, and the presence
of bidirectional streaming of suprathermal electrons was developed for this purpose. Additional requirements on the algorithm
include the ability to identify the passage of forward shocks, reasonable levels of hysteresis and persistence, and the ability
to modify the algorithm by changes in stored constants rather than changes in the software. After a few minor adjustments,
the algorithm performed well during the initial portion of the mission.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
663.
Kamide Y. Kihn E.A. Ridley A.J. Cliver E.W. Kadowaki Y. 《Space Science Reviews》2003,107(1-2):307-316
We report the recent progress in our joint program of real-time mapping of ionospheric electric fields and currents and field-aligned
currents through the Geospace Environment Data Analysis System (GEDAS) at the Solar-Terrestrial Environment Laboratory and
similar computer systems in the world. Data from individual ground magnetometers as well as from the solar wind are collected
by these systems and are used as input for the KRM and AMIE magnetogram-inversion algorithms, which calculate the two-dimensional
distribution of the ionospheric parameters. One of the goals of this program is to specify the solar-terrestrial environment
in terms of ionospheric processes, providing the scientific community with more than what geomagnetic activity indices and
statistical models provide.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
664.
Frey H.U. Mende S.B. Immel T.J. Gérard J.-C. Hubert B. Habraken S. Spann J. Gladstone G.R. Bisikalo D.V. Shematovich V.I. 《Space Science Reviews》2003,109(1-4):255-283
Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of the multi-wavelength imaging is to study the global auroral particle and energy input from the magnetosphere into the atmosphere. This paper describes the method for quantitative interpretation of FUV measurements. The Wide-Band Imaging Camera (WIC) provides broad band ultraviolet images of the aurora with maximum spatial resolution by imaging the nitrogen lines and bands between 140 and 180 nm wavelength. The Spectrographic Imager (SI), a dual wavelength monochromatic instrument, images both Doppler-shifted Lyman-α emissions produced by precipitating protons, in the SI-12 channel and OI 135.6 nm emissions in the SI-13 channel. From the SI-12 Doppler shifted Lyman-α images it is possible to obtain the precipitating proton flux provided assumptions are made regarding the mean energy of the protons. Knowledge of the proton (flux and energy) component allows the calculation of the contribution produced by protons in the WIC and SI-13 instruments. Comparison of the corrected WIC and SI-13 signals provides a measure of the electron mean energy, which can then be used to determine the electron energy flux. To accomplish this, reliable emission modeling and instrument calibrations are required. In-flight calibration using early-type stars was used to validate the pre-flight laboratory calibrations and determine long-term trends in sensitivity. In general, very reasonable agreement is found between in-situ measurements and remote quantitative determinations. 相似文献
665.
Moore T.E. Collier M.R. Fok M.-C. Fuselier S.A. Khan H. Lennartsson W. Simpson D.G. Wilson G.R. Chandler M.O. 《Space Science Reviews》2003,109(1-4):351-371
Development of the low energy neutral atom (LENA) imager was originally motivated by a need to remotely sense plasma heating in the topside ionosphere, with the goal of greatly enhanced temporal resolution of an otherwise familiar phenomenon. During ground test and calibration, the LENA imager was found to respond to neutral atoms with energies well above its nominal energy range of 10–750 eV, up to at least 3–4 keV, owing to sputtering interactions with its conversion surface. On orbit, LENA has been found to respond to a ubiquitous neutral atom component of the solar wind, to the neutral atoms formed by magnetosheath interactions with the geocorona during periods of high solar wind pressure, and to the interstellar neutral atoms flowing through the heliosphere during the season of maximal relative wind velocity between spacecraft and interstellar medium. LENA imaging has thus emerged as a promising new tool for studying the interplanetary medium and its interaction with the magnetosphere, in addition to the ionospheric heating and outflow that result from this interaction. LENA emissions from the ionosphere consist of a fast component that can be observed at high altitudes, and slower components that evidently create a quasi-trapped extended superthermal exosphere. The more energetic emissions are responsive to solar wind energy inputs on time scales of a few minutes. 相似文献
666.
We review observations from Voyager 2 of CIRs and merged CIRs in the outer heliosphere. The rather simple characteristics
of the CIR-associated changes in plasma, magnetic field, and particles become more complex as observations are made at greater
and greater distances. Pickup ions from charge exchange undoubtedly play an important role in the structure, but the full
details are not yet understood.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
667.
未来几年,世界民用和军用航空发动机的年产量可能达到9500台,与过去10年相比,年产量大约增加2000台,销售额也将大幅增加。虽然目前受军用和民用市场的刺激,发动机产量提高了,但是不久可能会出现下滑。 相似文献
668.
669.
We present results derived from the analysis of an equatorial streamer structure as observed by the UVCS instrument aboard
SOHO. From observations of the H I Lyα and Lyβ lines we infer the density and temperature of the plasma. We develop a preliminary
axisymmetric, magnetostatic model of the corona which includes the effects of gas pressure gradients on the magnetic structure.
We infer a coronal plasma β > 1 in the closed field regions and near the cusp of the streamer. We add to the model a parallel
velocity field assuming mass flux conservation along magnetic flux tubes. We then compute the Lyα emissivity and the line-of-sight
integrals to obtain images of Lyα intensity, taking into account projection effects and Doppler dimming. The images we obtain
from this preliminary model are in good general agreement with the UVCS observations, both qualitatively and quantitatively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
670.
Examination of the spatial distribution of CO intensity of Comet Halley indicates that a large fraction of CO originates from
the refractory organic component in the coma, rather than directly from the volatiles in the nucleus. Based on the fluffy
aggregate interstellar dust comet model, we have estimated the upper limits of the total amount of CO provided by coma dust.
The implications from the comparison of the predicted results with the observed value have been discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献