Life cycles of spots on Jupiter from Cassini images     

Liming Li  Andrew P. Ingersoll  Carolyn C. Porco  Shawn P. Ewald 《Icarus》2004,172(1):9-23

Using the sequence of 70-day continuum-band (751 nm) images from the Cassini Imaging Science System (ISS), we record over 500 compact oval spots and study their relation to the large-scale motions. The ∼100 spots whose vorticity could be measured—the large spots in most cases—were all anticyclonic. We exclude cyclonic features (chaotic regions) because they do not have a compact oval shape, but we do record their interactions with spots. We distinguish probable convective storms from other spots because they appear suddenly, grow rapidly, and are much brighter than their surroundings. The distribution of lifetimes for spots that appeared and disappeared during the 70-day period follows a decaying exponential with time constant (mean lifetime) of 3.5 days for probable convective storms and 16.8 days for all other spots. Extrapolating the exponential beyond 70 days seriously underestimates the number of spots that existed for the entire 70-day period. This and other evidences (size, shape, distribution in latitude) suggest that these long-lived spots with lifetime larger than 70 days are from a separate population. The zonal wind profile obtained manually by tracking individual features (this study) agrees with that obtained automatically by correlating brightness variations in narrow latitude bands (Porco et al., 2003). Some westward jets have developed more curvature and some have developed less curvature since Voyager times, but the number of westward jets that violate the barotropic stability criterion is about the same. In the northern hemisphere the number of spots is greatest at the latitudes of the westward jets, which are the most unstable regions according to the barotropic stability criterion. During the 70-day observation period the Great Red Spot (GRS) absorbed nine westward-moving spots that originated in the South Equatorial Belt (SEB), where most of the probable convective storms originate. Although the probable convective storms do not directly transform themselves into westward-moving spots, their common origin in the SEB suggests that moist convection and the westward jet compose a system that has maintained the GRS over its long lifetime.  相似文献   

Book reviews     

Rudolf Brázdil  William B. Morgan 《GeoJournal》1992,27(3):319-320

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Including the Urban Canopy Layer in a Lagrangian Particle Dispersion Model     

Stöckl  Stefan  Rotach  Mathias W.  Kljun  Natascha 《Boundary-Layer Meteorology》2022,183(1):1-33

Boundary-Layer Meteorology - When wind blows over the ocean, short wind-waves (of wavelength smaller than 10 m) are generated, rapidly reaching an equilibrium with the overlying turbulence (at...  相似文献   

Damage Potential and Losses Resulting from Snow Avalanches in Settlements of the Canton of Grisons,Switzerland   总被引：2，自引：1，他引：1  

Sven?FuchsEmail author  Michael?Bründl 《Natural Hazards》2005,34(1):53-69

In the field of natural hazards, risk is usually expressed as a function of probability of occurrence and damage potential. A key factor in the development of avalanche risk is a change in damage potential. In this paper, the development of damage potential and losses is analysed for settlements in the canton of Grisons, Switzerland for the period between 1950 and 2000. The spatial development patterns of the residential population and the insured value of buildings on a municipal level are described. These patterns are overlain by an accentuated occurrence of avalanches that caused damage to buildings. Extensive results from areas threatened by avalanches in the municipality of Davos are presented. Although the natural avalanche activity remained constant during the last decades, the total amount of damage decreased due to mitigation measures. The example of the municipality of Davos shows that mitigation measures are able to compensate an increase of tangible assets which leads to a reduced avalanche risk compared to earlier decades.  相似文献   

The Atmospheric Boundary Layer Over Baltic Sea Ice   总被引：4，自引：0，他引：4  

Burghard?BrümmerEmail author  Amèlie?Kirchg??ner  Gerd?Müller 《Boundary-Layer Meteorology》2005,117(1):91-109

A new parametrization for the surface energy balance of urban areas is presented. It is shown that this new method can represent some of the important urban phenomena, such as an urban heat island and the occurrence of a near-neutral nocturnal boundary layer with associated positive turbulent heat fluxes, unlike the traditional method for representing urban areas within operational numerical weather prediction (NWP) models. The basis of the new parametrization is simple and can be applied easily within an operational NWP model. Also, it has no additional computational expense compared to the traditional scheme and is hence applicable for operational forecasting requirements. The results show that the errors for London within the Met Office operational mesoscale model have been significantly reduced since the new scheme was introduced. The bias and root-mean-square (rms) errors have been approximately halved, with the rms error now similar to the model as a whole. The results also show that a seasonal cycle still exists in the model errors, but it is suggested that this may be caused by anthropogenic heat sources that are neglected in the urban scheme.The British Crowns right to retain a non-exclusive royalty-free license in and to any copyright is acknowledged.  相似文献   

Monitoring of Air Pollution in Latvia Between 1990 and 2000 Using Moss     

O. Nikodemus  G. Brūmelis  G. Tabors  L. Lapia  S. Pope 《Journal of Atmospheric Chemistry》2004,49(1-3):521-531

The concentrations of heavy metals (Cd, Cr, Cu, Pb, Ni, V, Zn) in feather moss were estimated in national surveys in Latvia in 1990, 1995 and 2000. Hylocomium splendens was used as a biomonitor in 1990 and Pleurozium schreberi in the latter two years. Maps of the distributions of the metals in Latvia have been produced. The paper discusses the reasons underlying the distributions and also the temporal trends during the last ten years.  相似文献   

Changes in Element Concentrations in Moss Segments After Cross-Transplanting Between a Polluted and Non-Polluted Site     

G. Tabors  G. BrŪmelis  L. Lapina  G. Pospelova  O. Nikodemus 《Journal of Atmospheric Chemistry》2004,49(1-3):191-197

To test the ability of Hylocomium splendens segments to retain absorbed heavy metals (Fe, V and Pb) and some physiological elements (Ca, Mg and K) over a period of some years, moss turf was cross-transplanted between polluted and background sites. Thereby it was possible to determine how quickly the concentrations in moss can reach chemical equilibrium with the atmospheric inputs. At a particular site (background or polluted), the physiological elements in transplanted material quickly reached the levels in the non-transplanted moss. For the heavy metals, the concentrations remained stable over 3 years in moss cross-transplanted from a polluted to a background site. There appeared to be inherent differences between moss at the background and polluted sites in the ability to absorb and accumulate heavy metals.  相似文献   

Signal-to-noise analysis of time-dependent greenhouse warming experiments     

Benjamin D Santer  Wolfgang Brüggemann  Ulrich Cubasch  Klaus Hasselmann  Heinke Höck  Ernst Maier-Reimer  Uwe Mikolajewica 《Climate Dynamics》1994,9(6):267-285

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Abolitionist Geographies          下载免费PDF全文

Martin Brückner 《Geographical review》2016,106(2):e34-e37

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Comment on: “Corrections to the Mathematical Formulation of a Backwards Lagrangian Particle Dispersion Model” by Gibson and Sailor (2012: Boundary-Layer Meteorology 145, 399–406)     

Stefan Stöckl  Mathias W. Rotach  Natascha Kljun 《Boundary-Layer Meteorology》2018,166(1):153-160

We discuss the results of Gibson and Sailor (Boundary-Layer Meteorol 145:399–406, 2012) who suggest several corrections to the mathematical formulation of the Lagrangian particle dispersion model of Rotach et al. (Q J R Meteorol Soc 122:367–389, 1996). While most of the suggested corrections had already been implemented in the 1990s, one suggested correction raises a valid point, but results in a violation of the well-mixed criterion. Here we improve their idea and test the impact on model results using a well-mixed test and a comparison with wind-tunnel experimental data. The new approach results in similar dispersion patterns as the original approach, while the approach suggested by Gibson and Sailor leads to erroneously reduced concentrations near the ground in convective and especially forced convective conditions.  相似文献