Clouds in the atmospheres of extrasolar planets. II. Thermal emission spectra of Earth-like planets influenced by low and high-level clouds

We study the impact of multi-layered clouds (low-level water and high-level ice clouds) on the thermal emission spectra of Earth-like planets orbiting different types of stars. Clouds have an important influence on such planetary emission spectra due to their wavelength dependent absorption and scattering properties. We also investigate the influence of clouds on the ability to derive information about planetary surface temperatures from low-resolution spectra.Comment: accepted for publication in A&

Clouds in the atmospheres of extrasolar planets. I. Climatic effects of multi-layered clouds for Earth-like planets and implications for habitable zones

The effects of multi-layered clouds in the atmospheres of Earth-like planets orbiting different types of stars are studied. The radiative effects of cloud particles are directly correlated with their wavelength-dependent optical properties. Therefore the incident stellar spectra may play an important role for the climatic effect of clouds. We discuss the influence of clouds with mean properties measured in the Earth's atmosphere on the surface temperatures and Bond albedos of Earth-like planets orbiting different types of main sequence dwarf stars.Comment: accepted for publication in A&

Inductive Proof Outlines for Monitors in Java

Abstract. The research concerning Java’s semantics and proof theory has mainly focussed on various aspects of sequential sub-languages. Java, however, integrates features of a class-based object-oriented language with the notion of multi-threading, where multiple threads can concurrently execute and exchange information via shared instance variables. Furthermore, each object can act as a monitor to assure mutual exclusion or to coordinate between threads. In this paper we present a sound and relatively complete assertional proof system for Java’s monitor concept, which generates verification conditions for a concurrent sublanguage JavaMT of Java. This work extends previous results by incorporating Java’s monitor methods

Einfluss von Wolken auf den Strahlungshaushalt der Erde berechnet mit dem ISCCP C1-Datensatz

This study examines the cloud effect on the radiation budget at the top of the atmosphere by use of the ISCCP daylight cloud data (C1) in combination with a Two-Stream-Model. Two tests are performed: the modelled narrowband filtered radiances are verified against the ISCCP satellite observation data (internal test) and the modelled broadband fluxes are compared against ERBE data (external tests). After both tests are succesfully concluded, the outgoing longwave radiation (OLR) for each of the 35 ISCCP cloud classes are determined. For better clarity we summarized the 35 cloud classes into 9 ones (3 top heights, 3 optical depths). Global monthly and annual means of the albedo and greenhouse effect of these 9 cloud types are given for one month of each season (April, July, October 1985, January 1986). For the global annual mean cloud radiative cooling of the earth in the shortwave spectral range dominates over cloud radiative warming in the longwave spectral range by a factor of 2. Seasonal variations of the net effect are mainly due to the changes in the shortwave cloud forcing component (-43.3 to -52.9 Wm"-"2 (shortwave), 22.5 to 25.1 Wm"-"2 (longwave)). The mean cloud sensitivity related to cloud amount changes from -29.4 to -47.7 Wm"-"2. This is mainly due to the difference between the mean surface albedo of northern and southern hemisphere. A comparison with the results of other studies are shown. The effects of the 9 different cloud types are analysed in detail. Cooling, warming, and radiatively neutral cloud types could be distinguished. (orig.)Diese Arbeit untersucht den Einfluss von Wolken auf den Strahlungshaushalt der Erde am Atmosphaerenoberrand unter Verwendung der Tageslichtdaten des ISCCP C1-Datensatzes in Verbindung mit einem Zwei-Strom-Approximationsmodell. Zwei Tests wurden durchgefuehrt: Die simulierten schmalbandigen, gefilterten Strahldichten wurden mit den Beobachtungsdaten der ISCCP-Satelliten (interne Tests) und die breitbandigen Fluesse mit den ERBE-Daten (externe Tests) verglichen. Nachdem beide Tests erfolgreich abgeschlossen werden konnten, wurde die langwellige Ausstrahlung fuer jede der 35 ISCCP-Wolkenklassen bestimmt. Zur groesseren Klarheit wurden die 35 ISCCP-Wolkenklassen zu 9 (3 Gipfelhoehen, 3 optische Dicken) zusammengefasst. Globale Monats- und Jahresmittelwerte des Albedo- und des Treibhauseffektes dieser 9 Wolkentypen sind fuer einen Monat jeder Jahreszeit gegeben (April, Juli, Oktober 1985, Januar 1986). Im globalen Jahresmittel dominiert der Strahlungsenergieverlust durch Wolken im kurzwelligen ueber den Strahlungsenergiegewinn im langwelligen um das 2-fache. Jahreszeitliche Unterschiede des Nettoeffektes sind in erster Linie auf Aenderungen seiner kurzwelligen Komponente zurueckzufuehren (Effekt der Wolken auf die solare Einstrahlung: -43.9 bis -52.9 Wm"-"2, Einfluss der Wolken auf die terrestrische Ausstrahlung: 22.5 bis 25.1 Wm"-"2). Der mittlere Wolkenempfindlichkeitsparameter aendert sich in den untersuchten Monaten von -29.4 bis -47.7 Wm"-"2. Die Ursache liegt hauptsaechlich an der unterschiedlichen Oberflaechenalbedo von Nord- und Suedhalbkugel. Die Ergebnisse werden mit denen anderer Untersuchungen verglichen. Der Effekt der 9 verschiedenen Wolkentypen wird im Detail analysiert. ''Kuehlende'', ''waermende'' und ''strahlungsneutrale'' Wolken konnten unterschieden werden. (orig.)Available from TIB Hannover: RN 3292(245) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A Formal Executable Semantics of the JavaCard Platform

Abstract. We present a formal executable speci cation of two crucial JavaCard platform components, namely the Java Card Virtual Machine (JCVM) and the ByteCode Veri er (BCV). Moreover, we relate both components by giving a proof of correctness of the ByteCode Veri er. Both formalisations and proofs have been machined-checked using the proof assistant Coq.

Hoare Logic for Mutual Recursion and Local Variables

We present a (the first?) sound and relatively complete Hoare logic for a simple imperative programming language including mutually recursive procedures with call-by-value parameters as well as global and local variables. For such a language we formalize an operational and an axiomatic semantics of partial correctness and prove their equivalence