Large-scale thermodynamics of the stratosphere and mesosphere during the major stratospheric warming in 2003/2004   总被引：1，自引：0，他引：1  

P. Mukhtarov  D. Pancheva  B. Andonov  N.J. Mitchell  E. Merzlyakov  W. Singer  W. Hocking  C. Meek  A. Manson  Y. Murayama 《Journal of Atmospheric and Solar》2007,69(17-18):2338

The stratosphere–mesosphere response to the major sudden stratospheric warming (SSW) in the winter of 2003/2004 has been studied. The UKMO (UK Meteorological Office) data set was used to examine the features of the large-scale thermodynamic anomalies present in the stratosphere of the Northern Hemisphere. The vertical and latitudinal structure of the genuine anomalies, emphasized by removing the UKMO climatology, has been investigated as well. The features of the stratospheric anomalies have been related to the mesospheric ones in measured neutral winds from radars and temperatures from meteor radars (90 km). It was found that the stratospheric warming spread to the lower mesosphere, while cooling occurred in the upper mesosphere, a feature that may be related to the large vertical scales of the stationary planetary waves (SPWs). It was shown also that the beginning of the eastward wind deceleration in the stratosphere–mesosphere system coincided with the maximum amplification of the SPW1 accompanied by short-lived bursts of waves 2 and 3.  相似文献   

Integrated Futures for Europe’s Mountain Regions: Reconciling Biodiversity Conservation and Human Livelihoods   总被引：1，自引：1，他引：0  

Jonathan Mitchley  Martin F.Price  Joseph Tzanopoulos 《山地科学学报》2006,(4)

Introduction Europe's mountains cover nearly half of the continent's area (Price et al. 2004) and land cover varies significantly (European Commission 2004). In most massifs, except for Sicily, southern Greece, and the British Isles, forest cover is dominant. In northern Europe, grassland is proportionately more important, and much of the mountains of the British Isles is covered by moorland. In central and southern Europe, arable land is of far greater importance than grassland, with Med…  相似文献   

Ebbs and Flows in Recent U.S. Interstate Migration*     

Gary A. Manson  Richard E. Groop 《The Professional geographer》1996,48(2):156-166

Interstate migration exchanges in the United States are temporally and spatially transitory. Both the early and mid-1980s exhibited significant fluctuations in the origins and destinations of U.S. migrants, while the late 1980s and early 1990s were even more unstable. Regions once favored by interstate movers such as the West and the South, while remaining attractive, showed evidence of declining favor in the early 1990s. Meanwhile, numerous states in the national interior regained their attractiveness, including several that gained net migrants for the first time in decades. California exhibited a major turnaround in its migration, perturbing the entire U.S. migration system.  相似文献   

N2 and M2 lunar tides: atmospheric resonance revisited     

D. M. Schlapp  R. J. Stening  J. M. Forbes  A. H. Manson  C. E. Meek  R. A. Vincent 《Annales Geophysicae》1996,14(8):826-836

A numerical model has been used to calculate the atmospheric response to forcing at periods in the region of 12-13.5 h. The results show that the response is enhanced in the neighbourhood of 13 h. These results have been compared with lunar tidal analyses of mesospheric wind data and geomagnetic variations at a number of stations. It is found that the N₂ lunar tidal component (period 12.66 h) is significantly enhanced relative to the main lunar tidal component M₂ (period 12.42 h) in both types of data, compared with what would be expected from the gravitational tidal potential. This supports the predictions of the numerical model. An appreciable phase shift is also found in the experimental data between the N₂ and M₂ tides, agreeing in sense with what would be expected for a resonance at a period around 13 h.  相似文献   

Zonal mean and tidal dynamics from space: an empirical examination of aliasing and sampling issues     

J. M. Forbes  M. Kilpatrick  D. Fritts  A. H. Manson  R. A. Vincent 《Annales Geophysicae》1997,15(9):1158-1164

Interpretations of space-based measurements of atmospheric parameters in the mesosphere and thermosphere are complicated by large local-time variations at these altitudes. For this reason, satellite orbits are often preferred which precess through all local times one or more times per season. However, the local-time structure of the atmosphere is inherently non-stationary, which can lead to sampling and aliasing difficulties when attempting to deconvolve the measurements into zonal mean and tidal components. In the present study, hourly radar measurements of mesopause-region winds are used to form a mock data base which can be used to gain insight into implications of the aforementioned problems; the use of actual measurements introduces a realistic element of geophysical temporal variability. Assuming zonal symmetry (i.e., migrating tides superimposed on a zonal mean circulation), the radar measurements are sampled from the satellite perspective for orbital inclinations of 57° and 70°, and compared to the ground or true perspective. These comparisons provide realistic estimates of the errors to be expected when attempting to derive mean and tidal components from space-based measurements. For both diurnal and semidiurnal components, and the quoted satellite inclinations, acceptable errors (3–4 m/s rms) are obtained for data covering 24 h local time (i.e., ascending plus descending nodes); the corresponding errors for singlenode data (12 h local-time coverage) are of order 8–11 m/s, and therefore may not represent reliable estimates of the actual tidal components. There exist certain caveats in connection with the latter conclusion which are discussed.  相似文献   

Comparisons between Canadian prairie MF radars, FPI (green and OH lines) and UARS HRDI systems     

C. E. Meek  A. H. Manson  M. D. Burrage  G. Garbe  L. L. Cogger 《Annales Geophysicae》1997,15(9):1099-1110

Detailed comparisons have been completed between the MF radars (MFR) in the Canadian prairies and three other systems: two ground-based Fabry-Perot interferometers (FPI) and the UARS high resolution Doppler imager (HRDI) system. The radars were at Sylvan Lake (52°N, 114°W), Robsart (49°N, 109°W) and the main continuing facility is at Saskatoon (52°N, 107°W). Statistical comparisons of hourly mean winds (1988–1992) for the Saskatoon MFR and FPI (557.7 nm green line) using scatter plots, wind speed-ratios, and direction-difference histograms show excellent agreement for Saskatoon. No serious biases in speeds or directions occur at the height of best agreement, 98 km. If anything, the MFR speeds appear bigger. The same applies to the Sylvan Lake MFR and Calgary FPI, where the best height is 88 km. In both cases these are close to the preferred heights for the emission layers. Differences between measurements seen on individual days are likely related to the influence of gravity waves (GW) upon the optical and radar systems, each of which have inherent spatial averaging (350, 50 km respectively), as well as the spatial difference between the nominal measurement locations. For HRDI, similar statistical comparisons are made, using single-overpass satellite winds and hourly means (to improve data quality) from MFR. Heights of best agreement, based upon direction-difference histograms, are shown; there is a tendency, beginning near 87 km, for these MFR heights to be 2 or 3 km greater than the HRDI heights. Speeds at these heights are typically larger for the satellite (MFR/HRDI = 0.7-0.8). Reasons for the differences are investigated. It is shown that the estimated errors and short-term (90 min) differences are larger for HRDI than for the MFR, indicating more noise or GW contamination. This leads to modest but significant differences in median speed-ratio (MFR/HRDI < 1). Also, comparison of the two systems is made under conditions when they agree best and when they show large disagreement. For the latter cases both systems show higher relative errors, and the HRDI vectors are frequently small. It is suggested that spatial or temporal GW wind fluctuations are the likely cause of the larger HRDI-MFR disagreement when wind speeds are small. No satisfactory explanation exists for the overall discrepancy is speeds between the MFR and HRDI.  相似文献   

An intercomparison between the GSWM, UARS, and ground based radar observations: a case-study in January 1993     

S. E. Palo  M. E. Hagan  C. E. Meek  R. A. Vincent  M. D. Burrage  C. McLandress  S. J. Franke  W. E. Ward  R. R. Clark  P. Hoffmann  R. Johnson  D. Kürschner  A. H. Manson  D. Murphy  T. Nakamura  Yu. I. Portnyagin  J. E. Salah  R. Schminder  W. Singer  T. Tsuda  T. S. Virdi  Q. Zhou 《Annales Geophysicae》1997,15(9):1123-1141

The Global-Scale Wave Model (GSWM) is a steady-state two-dimensional linearized model capable of simulating the solar tides and planetary waves. In an effort to understand the capabilities and limitations of the GSWM throughout the upper mesosphere and thermosphere a comparative analysis with observational data is presented. A majority of the observational data used in this study was collected during the World Day campaign which ran from 20 January to 30 January 1993. During this campaign data from 18 ground-based observational sites across the globe and two instruments located on the UARS spacecraft were analyzed. Comparisons of these data with the simulations from the GSWM indicate that the GSWM results are in reasonable agreement with the observations. However, there are a number of cases where the agreement is not particularly good. One such instance is for the semidiurnal tide in the northern hemisphere, where the GSWM estimates may exceed observations by 50%. Through a number of numerical simulations, it appears that this discrepancy may be due to the eddy diffusivity profiles used by the GSWM. Other differences relating to the diurnal tide and the quasi-two-day wave are presented and discussed. Additionally, a discussion on the biases and aliasing difficulties which may arise in the observational data is alos presented.  相似文献   

Simultaneous observations of the 2-day wave at London (43°N, 81°W) and Saskatoon (52°N, 107°W) near 91 km altitude during the two years of 1993 and 1994     

T. Thayaparan  W. K. Hocking  J. MacDougall  A. H. Manson  C. E. Meek 《Annales Geophysicae》1997,15(10):1324-1339

Simultaneous observations are valuable in providing further insights into the character of the quasi 2-day wave. In this study we investigate the period and amplitude for the quasi 2-day wave near 91 km using MF radars at London and Saskatoon, Canada, and in addition look at possible values of the zonal wave number. The results of the present study bring out certain new aspects of the quasi 2-day wave at mid-latitudes in the Northern Hemisphere. In particular we show that the period of the quasi 2-day wave determined from our study (specially at large amplitudes) is smaller (46-47 h) than the 51-52 h period often suggested by other Northern Hemisphere results, and that the periods also showed variability as a function of time. We also draw attention to the annual variability, and especially highlight the occurrence of the wave in non-summer months. Our observations show significant wave correlation between the London and Saskatoon sites during time intervals of strong 2-day wave activity. These results suggest that the 2-day waves of 1993/4 are westward propagating waves of zonal wave number 3, although sometimes the zonal wave number 5 is also indicated (specially at large amplitudes). Our study also contributes additional mid-latitude geographical data which should aid in developing a better picture of the quasi 2-day wave.  相似文献   

IPUMS-Terra: integrated big heterogeneous spatiotemporal data analysis system     

David Haynes  Alex Jokela  Steven Manson 《Journal of Geographical Systems》2018,20(4):343-361

Big Geo Data promises tremendous benefits to the GIS Science community in particular and the broader scientific community in general, but has been primarily of use to the relatively small body of GIScientists who possess the specialized knowledge and methods necessary for working with this class of data. Much of the greater scientific community is not equipped with the expert knowledge and techniques necessary to fully take advantage of the promise of big spatial data. IPUMS-Terra provides integrated spatiotemporal data to these scholars by simplifying access to thousands of raster and vector datasets, integrating them and providing them in formats that are useable to a broad array of research disciplines. IPUMS-Terra exemplifies a new class of National Spatial Data Infrastructure because it connects a large spatial data repository to advanced computational resources, allowing users to access the needle of information they need from the haystack of big spatial data. The project is trailblazing in its commitment to the open sharing of spatial data and spatial tool development, including describing its architecture, process development workflows, and openly sharing its products for the general use of the scientific community.  相似文献   

Measurements of the solar spectrum between 30 and 128Å     

James E. Manson 《Solar physics》1972,27(1):107-129

The results of two rocket flights of grazing incidence monochromators designed to measure solar line intensities in the wavelength region between 30 and 128 Å are compared. One of these flights sampled a very quiet Sun, that of November 3, 1965, and has been reported previously. The other acquired data during a more active, but non-flaring, interval on August 8, 1967. Improvements in the data reduction techniques have led to a refinement in the former data, and these improvements together with instrumental changes provided increased resolution in the results from the latter flight. The changes in line intensities observed in these two experiments follow a pattern which is in general qualitative agreement with theoretical ionization equilibrium calculations for the solar corona. An analysis of these and other observations of the CVI L line suggests that this line is particularly sensitive to local solar activity.  相似文献