Das mittlere meridionale Temperaturprofil in der Troposphäre als Effekt von vertikalen und horizontalen Austauschvorgängen und Kondensationswärme

Summary A theoretical account is given for the mean meridional temperature profile in the troposphere (up to 11 km) by the aid of the theorem of turbulent heat conduction introducing the vertical and horizontal coefficients of exchange (Austausch) which show a different order of magnitude. It is necessary, however, to take into consideration the heat of condensation, liberated by condensation of the mean yearly precipitation on the earth and thereby supplied to the troposphere in the different latitudes, in order to obtain a theoretical solution capable of completely explaining the mean meridional temperature profile deduced from former observations in the free atmosphere. The mean temperature distribution on ground has been assumed to be known as it is established by the radiation balance of the ground showing the determined and wellknown zonal distribution. Furthermore, some noticeable details resulting from the theory and concerning the vertical structure of temperature in the troposphere and its state of equilibrium are derived. It is made clear how a temperature gradient <1° C/100 m comes about. Thus the mean meridional temperature profile is shown to be a determined state of equilibrium between vertical and horizontal exchange (Austausch) phenomena and processes of condensation taking place in the troposphere. These latter ones being confined to a certain layer of the lower atmosphere are of essential importance for the upper limitation of the troposphere.

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Résumé On donne une explication théorique du profil méridien moyen de température dans la troposphère (jusqu'à 11 km.) en s'appuyant sur le théorème de la conductibilité turbulente et en introduisant les coefficients d'échange turbulent dont l'ordre de grandeur n'est pas le même dans la verticale et dans l'horizontale. Il faut tenir compte de la chaleur de condensation libérée par les précipitations annuelles moyennes et qui est fournie à la troposphère aux différentes latitudes; alors seulement on arrive à une solution en accord complet avec le profil méridien de température, tel que le fournissent les observations aérologiques. On a considérée comme connue la distribution moyenne de la température au niveau du sol, celle-ci étant déterminée par le bilan radiatif du sol et présentant la répartition zonale bien connue. On expose ensuite thermique verticale de la troposphère et son équilibre, ainsi que l'établissement d'un gradient inférieur à un degré par cent mètres. Le profil méridien moyen de température apparaît alors comme le résultat d'un équilibre entre les processus d'échange turbulent verticaux et horizontaux et des phénomènes de condensation se produisant dans la troposphère. Le fait que ces derniers sont limités à une certaine couche basse de l'atmosphère est une des raisons pour lesquelles la troposphère présente une limite supérieure.

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Mit 4 Textabbildungen.     

Characterizing the dispersive state of convective boundary layers for applied dispersion modeling

Estimates from semiempirical models that characterize surface heat flux, mixing depth, and profiles of temperature, wind, and turbulence are compared with observations from atmospheric field studies conducted in Colorado, Illinois, Indiana, and Minnesota. Sodar observations are compared with tower measurements at the Colorado site, for wind and turbulence profiles. The median surface heat flux, as calculated using surface-layer flux-profile relationships and an energy budget model, was consistently overestimated by 20 to 80%. Several mixing-depth models were evaluated: (1) integration of the hourly surface heat flux and friction velocity, (2) solving for the time rate of change of profiles of virtual potential temperature, and (3) an interpolation scheme used by the U.S. Environmental Protection Agency in regulatory dispersion models. For the late afternoon, 80 to 90% of the estimates from the first and third models were within 40% of the observed values. For the morning hours after sunrise, all were less accurate. Temperature estimates from surface-layer flux-profile relationships compared well with observations within the mixed layer, but were too low for the inversion layer aloft. Wind profiles were derived using surface-layer flux-profile relationships, a windprofile power-law based on Pasquill stability category, and sodar measurements. The sodar measurements were superior to both types of model estimates. Turbulence profiles were derived from sodar measurements and from semiempirical similarity relationships based on mixing depth and Obukhov length. The scatter in the comparisons with the sodar observations is twice that seen in the comparisons with empirical profile relationships. Overall, it appears that uncertainty of as low as 20 to 30% in the characterization of the diffusion meteorology is the exception rather than the rule.On assignment from the National Oceanic and Atmospheric Administration, U. S. Department of Commerce.Disclaimer: Although the research described in this article has been supported by the United States Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Unique isoprene oxidation products demonstrate chlorine atom chemistry occurs in the Houston,Texas urban area

As part of the 2000 Texas Air Quality Study (TexAQS), we studied the isoprene oxidation process under ambient conditions to discern the presence of chlorine atom (Cl) chemistry in the Houston, Texas urban area. By measuring chloromethylbutenone (CMBO) and an isomer of chloromethylbutenal (CMBA), we clearly observed sixteen episodes of active Cl chemistry during the 24-day experiment. Estimated median Cl concentration during each of these episodes was between the detection limit of ~10² atoms cm⁻³ and 50 _{- 30} ^{+ 70} ×10⁴ 50_{ - 30}^{ + 70} \times {10^4} atoms cm⁻³. Cl concentration during all the episodes averaged 7.6 _{- 2.0} ^{+ 4.7} ×10⁴ 7.6_{ - 2.0}^{ + 4.7} \times {10^4} atoms cm⁻³ and thus amounted to less than 3% of the OH concentration during the same periods. During the episodes, the fraction of oxidation chemistry initiated by Cl ranged from 3–43% and was strongly dependent on the quantity and type of hydrocarbons present in the atmosphere. Because of its intermittent presence and low concentration, Cl is not a broadly influential oxidant in the Houston, Texas urban area.     

A Lee wave cloud climatology for pincher creek,Alberta

Abstract

The annual, monthly and diurnal frequencies and durations of wave clouds are summarized from twelve years of observations at Pincher Creek, Alberta. Wave clouds occur on an average of 141 days annually. There is a distinct winter maximum anda summer minimum of occurrence. Wave clouds occur on 50% or more of the days during October and February, the most active months. Wave clouds persist for longer periods in the cooler half of the year. There appears to be a marked diurnal variation in wave cloudfrequency with maxima in the afternoon, however, this may be due to decreased visibility at sunrise and sunset.     

Numerical simulation of the development of vortices over the Qinghai-Xizang (Tibet) Plateau

Summary Some of the vortices which develop over the Tibetan plateau during summer give rise to severe weather over eastern China. These weather developments can be difficult to forecast, but have been simulated successfully in a recently developed numerical model. It will be shown that different vortices respond differently to topographic effects, to nonlinear processes and to sensible and latent heating in their formation, maintenance, and motion. Elevated terrain appears to enhance the influence of thermodynamic processes, block airflow, and increase frictional dissipation.Sensible heating sometimes collaborates with topography in blocking cold air intrusions and is not only a function of terrain elevation but also of the synoptic situation. Without the input of latent heating, vortices over the eastern part of the Tibetan plateau tend to degenerate.

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Numerische Simulation von Wirbelbildungen über dem Hochland von Tibet

Zusammenfassung Einige der sich im Sommer über dem Hochland von Tibet entwickelnden Wirbel verursachen Unwetter in Ostchina. Die Vorhersage dieser Entwicklung kann schwierig sein, sie werden aber von einem kürzlich vorgestellten numerischen Modell erfolgreich simuliert. Es wird gezeigt, daß verschiedene Wirbel verschieden auf die Orographie, auf nichtlineare Vorgänge sowie auf fühlbare und latente Wärme in ihrer Entstehung, Erhaltung und Bewegung reagieren. Ein Hochland scheint den Einfluß thermodynamischer Vorgänge zu verstärken, Strömungen zu blockieren und die Reibungsdissipation zu steigern.Die fühlbare Wärme verhindert manchmal gemeinsam mit der Topographie Kaltlufteinbrüche, hängt aber nicht nur von der Hochland-sondern auch von der synoptischen Situation ab. Ohne latente Wärme neigen Wirbel über dem Ostteil des Hochlandes von Tibet zur Degeneration.

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With 22 Figures     

Assessment of hydrological alterations on wandering beetle assemblages (coleoptera: Carabidae and Tenebrionidae) in coastal wetlands of arid Mediterranean systems

Changes in wandering beetle assemblages (Carabidae and Tenebrionidae) of different habitats situated in coastal wetlands of a Mediterranean arid area (Mar Menor, SE Spain) were analysed in 1984, 1992 and 2003 by pitfall trapping. Over two decades, the increase in irrigated lands at watershed scale led to rising water tables in the Mar Menor wetlands, which affected their beetle communities. These hydrological changes caused an increase in the carabid population, particularly in the sites most affected by flooding, where halobionts and halophiles, which were practically absent in 1984 and 1992, had become dominant by 2003. In contrast, tenebrionid assemblages simplified with time and by 2003 were dominated by one or two generalist species.     

Storm rainfall conditions for floods and debris flows from recently burned areas in southwestern Colorado and southern California

Debris flows generated during rain storms on recently burned areas have destroyed lives and property throughout the Western U.S. Field evidence indicate that unlike landslide-triggered debris flows, these events have no identifiable initiation source and can occur with little or no antecedent moisture. Using rain gage and response data from five fires in Colorado and southern California, we document the rainfall conditions that have triggered post-fire debris flows and develop empirical rainfall intensity–duration thresholds for the occurrence of debris flows and floods following wildfires in these settings. This information can provide guidance for warning systems and planning for emergency response in similar settings.Debris flows were produced from 25 recently burned basins in Colorado in response to 13 short-duration, high-intensity convective storms. Debris flows were triggered after as little as six to 10 min of storm rainfall. About 80% of the storms that generated debris flows lasted less than 3 h, with most of the rain falling in less than 1 h. The storms triggering debris flows ranged in average intensity between 1.0 and 32.0 mm/h, and had recurrence intervals of two years or less. Threshold rainfall conditions for floods and debris flows sufficiently large to pose threats to life and property from recently burned areas in south-central, and southwestern, Colorado are defined by: I = 6.5D^− 0.7 and I = 9.5D^− 0.7, respectively, where I = rainfall intensity (in mm/h) and D = duration (in hours).Debris flows were generated from 68 recently burned areas in southern California in response to long-duration frontal storms. The flows occurred after as little as two hours, and up to 16 h, of low-intensity (2–10 mm/h) rainfall. The storms lasted between 5.5 and 33 h, with average intensities between 1.3 and 20.4 mm/h, and had recurrence intervals of two years or less. Threshold rainfall conditions for life- and property-threatening floods and debris flows during the first winter season following fires in Ventura County, and in the San Bernardino, San Gabriel and San Jacinto Mountains of southern California are defined by I = 12.5D^−0.4, and I = 7.2D^−0.4, respectively. A threshold defined for flood and debris-flow conditions following a year of vegetative recovery and sediment removal for the San Bernardino, San Gabriel and San Jacinto Mountains of I = 14.0D^−0.5 is approximately 25 mm/h higher than that developed for the first year following fires.The thresholds defined here are significantly lower than most identified for unburned settings, perhaps because of the difference between extremely rapid, runoff-dominated processes acting in burned areas and longer-term, infiltration-dominated processes on unburned hillslopes.     

Basin organization of nature management for solving hydroecological problems

Presented are the development of the concept and projects of the basin nature management and the organization of their implementation in the whole region using the basin-administrative approach. Based on the multidimensional analysis and forecast of river runoff variations using the artificial neural networks, the typification of catchments is carried out mainly defined by such factors as its area, order of the river, and degree of anthropogenic load. Depending on the hydrological functioning type, the adapted complexes of Hydroecological activities are determined. The need in the integration of the geodata for each river basin with the inherent morphological and process characteristics as well as of the results of Hydroecological monitoring enables to recommend the structure of the database of the basin organization of nature management in the regions of Russia based on the European experience in the river network monitoring in the context of the EU Water Framework Directive and of the creation of the single infrastructure of the spatial data.     

Global carbon budgets and the viability of new fossil fuel projects

Policy-makers of some fossil fuel-endowed countries wish to know if a given fossil fuel supply project is consistent with the global carbon budget that would prevent a 2 °C temperature rise. But while some studies have identified fossil fuel reserves that are inconsistent with the 2 °C carbon budget, they have not shown the effect on fossil fuel production costs and market prices. Focusing on oil, we develop an oil pricing and climate test model to which we apply future carbon prices and oil consumption from several global energy-economy-emissions models that simulate the energy supply and demand effects of the 2 °C carbon budget. Our oil price model includes key oil market attributes, notably upper and lower market share boundaries for different oil producer categories, such as OPEC. Using the distribution of the global model results as an indicator of uncertainty about future carbon prices and oil demand, we estimate the probability that a new investment of a given oil source category would be economically viable under the 2 °C carbon budget. In our case study of Canada’s oil sands, we find a less than 5% probability that oil sands investments, and therefore new oil pipelines, would be economically viable over the next three decades under the 2 °C carbon budget. Our sensitivity analysis finds that if OPEC agreed to reduce its market share to 30% by 2045, a significant reduction from its steady 40–45% of the past 25 years, then the probability of viable oil sands expansion rises to 30%.