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This article reviews the current state-of-the-art and future prospects of the microwave techniques for remote sensing of the
earth’s atmosphere and ocean. Geophysical parameters and their relationship with measured thermal microwave radiation is established
through radiative transfer processes. The atmospheric temperature profile obtained from microwave sounding unit (msu) onboardtiros-N series of satellites is operational and is used for numerical weather prediction. The demonstrated applications of scanning
multichannel microwave radiometer (smmr) onboard most recent and advancedseasat satellite are highlighted.The capability ofseasat active sensors for monitoring ocean parameters have also been indicated. Feasible applications of microwave techniquese.g. moisture profile with advanced moisture sounder (amsu), and surface pressure from multifrequency active microwave pressure sounder (mps) are also described. Finally the recent and advanced microwave limb sounding (mls) technique and its applications to upper atmospheric research has been reviewed. 相似文献
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HF doppler observations of the vertical drift velocity and group height of the 5.5 MHz plasma frequency level of the post-sunset
bottomside F-region obtained on a fewESF (equatorial spread-F) and non-ESF days at Trivandrum are presented. The results show that on the non-ESF days, the maximum group height attained is about 400 km and the maximum velocity is less than 30 m/sec. On theESF days, however, the corresponding values are found to be in the range of 400–650 km and 30–50 m/sec. TheESF onset is found to be significantly delayed relative to the velocity peak indicating that it is more closely linked to the
layer height than to the drift velocity. 相似文献
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Using quantitative indicators to evaluate results from variable-density groundwater flow models 总被引：1，自引：1，他引：0
Variable-density transport models are typically tested by comparing model output with the results of three standard test cases: (1) the HYDROCOIN Level 1, Case 5 salt dome problem—Organisation for Economic Co-operation and Development (OECD 1988), (2) the Henry (1964) approximate analytic solution for steady-state saltwater intrusion and (3) the Elder (1967) problem for complex natural convection where fluid flow is driven purely by fluid-density differences. The complex flow phenomena that result in many variable-density flow problems often means that the intercode testing (and the evaluation of results from variable-density flow models more generally) is largely limited to a visual inspection of isochlor distributions. Visual inspection can often be quite subjective, prone to errors and may not allow easy detection of discrepancies, especially when they are small. Moreover, a match of certain isochlors at a number of prescribed time intervals does not necessarily enure the model is adequately tested. Recently, the well-studied Elder problem has been the subject of significant discussion in the research literature. Authors such as Diersch and Kolditz (2002) have shown that the solutions obtained to the Elder problem are dependent upon the level of grid discretization used. Simpson and Clement (2003) stated that the results of the Elder problem can only be matched in a qualitative sense because the problem is highly sensitive to discretization. In this paper, a number of quantitative indicators are developed that can be used for a more rigorous quantitative evaluation of results of variable-density flow models. They may also find application in future model benchmarking practice.
Resumen Los modelos de transporte de densidad variable se prueban típicamente mediante la comparación de los resultados del modelo con los resultados de tres casos de prueba estándar: (1) el problema de domo de sal HYDROCOIN nivel 1, caso 5—Organización de desarrollo y cooperación económica (OECD 1988), (2) la solución analítica aproximada de Henry (1964) para la intrusión de sal en estado constante y (3) el problema de Elder (1967) para la convexión natural compleja donde el flujo de fluido es determinado únicamente por las diferencias de densidad entre fluidos. Los fenómenos de flujo complejo que resultan en varios problemas de flujo de densidad variable con frecuencia significan que las pruebas de intercodificación (y la evaluación de resultados de modelos de flujo de densidad variable más generalmente) se limita principalmente a una inspección visual de las distribuciones de la intrusión de agua salada. La inspección visual con frecuencia puede ser bastante subjetiva, propensa a errores y es posible que no permita detectar fácilmente las discrepancias, especialmente cuando son pequeñas. Más aún, la concordancia de ciertas intrusiones de agua salada en un número de intervalos de tiempo prescritos no necesariamente asegura que el modelo haya sido probado adecuadamente. Recientemente, el bien estudiado problema de Elder ha sido objeto de discusiones siginificativas en la literatura de investigación. Los autores tales como Diersch y Kolditz (2002) han mostrado que las soluciones obtenidas para el problema Elder dependen del nivel de discretización de mallas utilizado. Simpson y Clement (2003) afirman que los resultados del probelma de Elder se pueden corrobar únicamente en un sentido cualitativo porque el problema es sumamente sensible a la discretización. En este artículo se ha desarrollado un número de indicadores cuantitativos que pueden ser utlizados para una evaluación cuantitativa más rigurosa de los resultados de los modelos de flujo de densidad variable. Es posible que también se puedan aplicar en el futuro para prácticas de modelos de benchmarking.
Résumé Utilisation dindicateurs quantitatifs pour lévaluation de modèles découlement à densité variable de leau souterraine. On évalue généralement les modèles de transport à densité variable en comparant les résultats obtenus grâce à ces modèles aux résultats de trois essais standards: (1) le problème «dôme de sel» HYDROCOIN, niveau 1, cas 5—Organisation de coopération et de développement économiques (OCDE 1988), (2) la solution analytique approximative de Henry (1964) pour lintrusion deau salée en régime permanent, et (3) le problème de Elder (1976) pour la convection naturelle complexe, où lécoulement du fluide est engendré par les seules différences de densité. Les phénomènes complexes découlement qui résultent de plusieurs problèmes découlement à densité variable signifient souvent que la comparaison entre codes (et lévaluation des résultats des modèles découlement à densité variable en général) est largement limitée à linspection visuelle des isocontours. Linspection visuelle peut souvent être assez subjective, elle peut comporter des erreurs, et il peut être difficile, par ce moyen, de détecter des différences, surtout lorsquelles sont faibles. De plus, la vérification des isocontours pour un nombre déterminé dintervalles de temps ne garantit pas que le modèle ait été mis à lépreuve de façon satisfaisante. Récemment, le modèle élaboré de Elder a été lobjet de plusieurs discussions significatives dans la littérature de la recherche. Des auteurs comme Diersch and Kolditz (2002) ont démontré que les solutions obtenues pour le problème dElder dépendaient du niveau de discrétisation du maillage utilisé. Simpson et Clement (2003) ont affirmé que les résultats du problème dElder pouvaient seulement être comparés dune manière qualitative, puisque la discrétisation influe de manière marquée sur le problème. Dans cet article, une série dindicateurs quantitatifs sont mis sur pied pour permettre une utilisation plus rigoureuse de lévaluation quantitative des résultats de modèles découlement à densité variable. Ces indicateurs pourraient également trouver leur utilité dans la pratique de la calibration des modèles.Utilización de indicadores cuantitativos para evaluar los resultados de modelos de flujo de aguas subterráneas de densidad variable.相似文献
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P. N. Mahajan 《Journal of Earth System Science》2001,110(3):225-229
Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water
vapour over the Indian seas. Integrated water vapour obtained from these algorithms is compared with that derived from radiosonde
observations at Minicoy and Port Blair islands. Algorithm-3 of Schlussel and Emery (1990) performed best. On the basis of
this algorithm, distribution of integrated water vapour is determined during the monsoon depression (22nd–27th July, 1992)
that formed over the Bay of Bengal. 相似文献
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NAVEEN R SHAHI NEERAJ AGARWAL ALOKE K MATHUR ABHIJIT SARKAR 《Journal of Earth System Science》2011,120(3):337-345
An atmospheric correction method has been applied on sea surface temperature (SST) retrieval algorithm using Very High Resolution
Radiometer (VHRR) single window channel radiance data onboard Kalpana satellite (K-SAT). The technique makes use of concurrent
water vapour fields available from Microwave Imager onboard Tropical Rainfall Measuring Mission (TRMM/TMI) satellite. Total
water vapour content and satellite zenith angle dependent SST retrieval algorithm has been developed using Radiative Transfer
Model [MODTRAN ver3.0] simulations for Kalpana 10.5–12.5 μm thermal window channel. Retrieval of Kalpana SST (K-SST) has been
carried out for every half-hourly acquisition of Kalpana data for the year 2008 to cover whole annual cycle of SST over Indian
Ocean (IO). Validation of the retrieved corrected SST has been carried out using near-simultaneous observations of ship and
buoys datasets covering Arabian Sea, Bay of Bengal and IO regions. A significant improvement in Root Mean Square Deviation
(RMSD) of K-SST with respect to buoy (1.50–1.02 K) and to ship datasets (1.41–1.19 K) is seen with the use of near real-time
water vapour fields of TMI. Furthermore, comparison of the retrieved SST has also been carried out using near simultaneous
observations of TRMM/TMI SST over IO regions. The analysis shows that K-SST has overall cold bias of 1.17 K and an RMSD of
1.09 K after bias correction. 相似文献
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M S Narayanan P K Pal P C Joshi M Mali Baby Simon 《Journal of Earth System Science》1989,98(3):247-254
Water vapour tracers can provide useful information on winds at ≈ 500mb by observing the 6·7μ radiances. This fills the data
gap in the cloud motion winds provided by conventional meteorological geostationary satellites. There is no geostationary
satellite at present over the Indian Ocean with 6·7μ imaging capability to provide mid-tropospheric winds. The potentials
of 6·7μ radiances, available from polar orbiting satellites, for mid-tropospheric circulation features have been examined
in this study. Tiros-N satellite data of May 1979 and ECMWF level-IIIb wind data were analysed to relate the radiances with
the streamlines. We find that the radiances of 6·7μ from orbiting satellites agree well with the wind field. 相似文献
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Albrecht Steck 《Swiss Journal of Geoscience》2008,101(2):515-546
This study presents a review of published geological data, combined with original observations on the tectonics of the Simplon
massif and the Lepontine gneiss dome in the Western Alps. New observations concern the geometry of the Oligocene Vanzone back
fold, formed under amphibolite facies conditions, and of its root between Domodossola and Locarno, which is cut at an acute
angle by the Miocene, epi- to anchizonal, dextral Centovalli strike-slip fault. The structures of the Simplon massif result
from collision over 50 Ma between two plate boundaries with a different geometry: the underthrusted European plate and the
Adriatic indenter. Detailed mapping and analysis of a complex structural interference pattern, combined with observations
on the metamorphic grade of the superimposed structures and radiometric data, allow a kinematic model to be developed for
this zone of oblique continental collision. The following main Alpine tectonic phases and structures may be distinguished:
It is suggested that movements of shortening in fan shaped NW, W and SW directions accompanied the more regular NW- to WNW-directed
displacement of the Adriatic indenter during continental collision.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Editorial Handling: Stefan Bucher 相似文献
| 1. | NW-directed nappe emplacement, starting in the Early Eocene (~50 Ma); |
| 2. | W, SW and S-verging transverse folds; |
| 3. | transpressional movements on the dextral Simplon ductile shear zone since ~32 Ma; |
| 4. | formation of the Bergell – Vanzone backfolds and of the southern steep belt during the Oligocene, emplacement of the mantle derived 31–29 Ma Bergell and Biella granodiorites and porphyritic andesites as well as intrusions of 29–25 Ma crustal aplites and pegmatites; |
| 5. | formation of the dextral discrete Rhone-Simplon line and the Centovalli line during the Miocene, accompanied by the pull-apart development of the Lepontine gneiss dome – Dent Blanche (Valpelline) depression. |
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Editorial Handling: Stefan Bucher 相似文献
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An environmental model to compute microwave brightness temperatures for downward looking radiometers on board satellite is described. The effects of water vapour, oxygen and clouds on the brightness temperature have been studied for frequencies from 5 to 50 GHz for a standard tropical atmosphere. The effect of look angle on brightness temperture has also been investigated. Based on the model it has been shown that while the radiometers on boardBhaskara at 19·35 and 22·235 GHz are capable of giving the atmospheric water vapour and liquid water contents, the ability to distinguish these quantities is more for the combination of the frequencies 22·235 and 31 GHz. 相似文献
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Eran Feitelson 《Hydrogeology Journal》2006,14(3):319-329
The reliance on aquifers which are shared by more than one country is increasing. Yet, shared aquifers are only rarely addressed in international treaties, despite the wide recognition of the desirability of comprehensive coordinated management. In order to identify the impediments to reaching agreements on the management of shared aquifers, and the factors that may assist in overcoming these impediments, the political economy of transboundary groundwater exploitation is outlined, and the Israeli-Palestinian case examined. It is argued that the main impediment to the conclusion of international agreements on groundwater is the array of domestic power structures, and particularly the power of small cohesive interest groups. The analysis of the Israeli-Palestinian 1995 interim agreement, and the negotiations leading to it, suggest that this impediment can be overcome, if the domestic interests are recognized in advance, and addressed in the agreement. It also shows that high level politics can play a positive role in forcing water negotiators to conclude an agreement.
相似文献
| Eran FeitelsonEmail: Phone: +972-2-5883346Fax: +972-2-5881200 |