排序方式： 共有5条查询结果，搜索用时 15 毫秒
1
1.
The four entry probes of the Pioneer Venus mission measured the radiative net flux in the atmosphere of Venus at latitudes of 60°N, 31°S, 27°S, and 4°N. The three higher latitude probes carried instruments (small probe net flux radiometers; SNFR) with external sensors. The measured SNFR net fluxes are too large below the clouds, but an error source and correction scheme have been found (H. E. Revercomb, L. A. Sromovsky, and V. E. Suomi, 1982, Icarus52, 279–300). The near-equatorial probe carried an infrared radiometer (LIR) which viewed the atmosphere through a window in the probe. The LIR measurements are reasonable in the clouds, but increase to physically unreasonable levels shortly below the clouds. The probable error source and a correction procedure are identified. Three main conclusions can be drawn from comparisons of the four corrected flux profiles with radiative transfer calculations: (1) thermal net fluxes for the sounder probe do not require a reduction in the Mode 3 number density as has been suggested by O. B. Toon, B. Ragent, D. Colburn, J. Blamont, and C. Cot (1984, Icarus57, 143–160), but the probe measurements as a whole are most consistent with a significantly reduced mode 3 contribution to the cloud opacity; (2) at all probe sites, the fluxes imply that the upper cloud contains a yet undetected source of IR opacity; and (3) beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and water vapor mixing ratios of about 2–5 × 10?5 near 60°, 2–5 × 10?4 near 30°, and 5 × 10?4 near the equator. The suggested latitudinal variation of IR cooling is consistent with descending motions at high latitudes, and it is speculated that it could provide an important additional drive for the general circulation. 相似文献
2.
Summary An analog data reduction system for obtaining variance spectra of stationary time series is described and its accuracy is discussed. This equipment was developed to reduce data obtained with the sonic anemometer. The variance spectra of the vertical wind component observed with the sonic anemometer in 1953 at O'Neill, Nebraska, are presented in Table 1.
With 5 Figures
The research reported in this document has been sponsored in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, under Contract No. AF 19 (603)-1384. 相似文献
Zusammenfassung Es wird ein Auswertesystem beschrieben, welches auf dem elektronischen Analogieprinzip beruht und für Berechnung der Varianzspektren in stationärer Turbulenz Verwendung findet. Die Genauigkeitsgrenzen werden erörtert. Dieses System wurde für die Auswertung von Beobachtungen mittels eines akustischen Anemometers entwickelt. Beispiele von Varianzspektren der vertikalen Windkomponente nach Beobachtungen in O'Neill, Nebraska, 1953, werden angeführt.
Résumé Exposé d'une méthode de depouillement reposant sur le principe d'analogie électronique et trouvant application dans le calcul des spectres de variance de la turbulence stationnaire. Limites de précision. Le procédé a été employé pour le dépouillement d'observations obtenues à partir d'un anémomètre acoustique. Exemples de spectres de variance de la composante verticale de vent d'après des observations faites à O'Neill, Nebraska en 1953.
With 5 Figures
The research reported in this document has been sponsored in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, under Contract No. AF 19 (603)-1384. 相似文献
3.
The interpretation of unexpected characteristics of Pioneer Venus temperature measurements, and of the large difference between these and the Venera results, is aided by new Venus temperature profiles derived from engineering measurements of the Pioneer Venus Small-Probe Net Flux Radiometer (SNFR) instruments. To facilitate correction of a temperature-dependent radiometric response, these instruments monitored the temperatures of their deployed radiation detectors. The accurate calibration of the temperature sensors, and their strong thermal coupling to the atmosphere, make it possible to deduce atmospheric temperatures within 2°K (at most altitudes) using a simple two-component thermal model to account for lag effects. These independent temperature profiles generally confirm to high accuracy, the small-probe results of A. Seiff, D. B. Kirk, R. E. Young, R. C. Blanchard, J. T. Findlay, G. M. Kelly, and S. C. Sommer (1980a, J. Geophys. Res.85, pp. 7903–7933) concerning vertical structure and horizontal contrast in the lower atmosphere, although the stable layer below 25 km is found to be slightly more stable (by about 0.4°K/km) and absolute temperatures are an average of 2°K higher. The measured Day-Night thermal contrast is compatible with predicted responses to the diurnal variation in solar heating, except near the cloud base, where 3–5°K differences may be due to thermal radiative heating differences associated with different cloud opacities. Temperature contrasts between latitudes 30 and 60° are roughly consistent with cyclostrophic balance. But pressure and temperature measurements by the Pioneer Venus Sounder probe at 4° latitude, when compared to Small-probe results, imply unreasonably large equatorward accelerations of 100 (m/sec)/day. Poleward accelerations compatible with cyclostrophic balance can be obtained if Sounder-probe temperatures are increased by a scale-factor correction reaching 6–7°K at 13 km. 相似文献
4.
Spatial information on climatic characteristics is beneficial in e.g. regional planning, building construction and urban ecology. The possibility to spatially predict urban?Crural temperatures with statistical techniques and small sample sizes was investigated in Turku, SW Finland. Temperature observations from 36 stationary weather stations over a period of 6?years were used in the analyses. Geographical information system (GIS) data on urban land use, hydrology and topography served as explanatory variables. The utilized statistical techniques were generalized linear model and boosted regression tree method. The results demonstrate that temperature variables can be robustly predicted with relatively small sample sizes (n????20?C40). The variability in the temperature data was explained satisfactorily with few accessible GIS variables. Statistically based spatial modelling provides a cost-efficient approach to predict temperature variables on a regional scale. Spatial modelling may aid also in gaining novel insights into the causes and impacts of temperature variability in extensive urbanized areas. 相似文献
5.
Net radiative flux measurements by instruments on the Pioneer Venus Day, North, and Night probes are too large below 30 km to be consistent with present estimates of atmospheric opacity. We evaluate the only known mechanisms which could potentially have caused significant errors in the deep atmosphere, namely, (1) radiation field perturbations behind each probe due to its thermal wake, (2) cloud particle deposition on the sensor windows, and (3) thermal perturbations within the radiation sensor produced by gas flow through the sensor window retainers. Thermal analysis of the wake effect shows that temperature perturbations are not large enough to produce significant flux perturbations when gas opacity and sensor field-of-view characteristics are taken into account. The particle deposition effect is rejected because it requires a signature in the measured radiation profile which is not observed. The absence of such a feature also implies that mode 3 cloud particles are either not sulfuric acid or are far less numerous than previously reported. We find that the third mechanism is the most likely source of the large net flux measurements. However, this error is not sufficiently constrained by laboratory data to allow rigorous corrections to the measured flux profiles. If we use radiative transfer calculations to constrain the fluxes at 14 km and limited laboratory data to estimate the altitude dependence of the error, then we obtain a plausible set of corrected flux profiles which are roughly consistent with reasonable H2O mixing ratios below the clouds. 相似文献
1