Proceedings of the 11th International Conference, TPHOLs’98 Canberra, Australia, September–October 1998. Supplementary Proceedings

Mechanical theorem provers for higher order logics have been successfully applied in many areas including hardware verification and synthesis; verification of security and communications protocols; software verification, transformation and refinement; compiler construction; and concurrency. The higher order logics used to reason about these problems and the underlying theorem prover technology that support them are also active areas of research. The International Conference on Theorem Proving in Higher Order Logics (TPHOLs) brings together people working in these and related areas for the discussion and dissemination of new ideas in the field. TPHOLs'98 continues the conference tradition of having both a completed work and work-in-progress stream. The Papers from the first stream were formally refereed, and published as volume 1479 of LNCS. This, supplementary, proceedings records work accepted under the work-in-progress category, and is intended to document emerging trends in higher-order logic research. Papers in the work-in-progress stream are vetted for relevance and contribution before acceptance. The work-in-progress stream is regarded as an important feature of the conference as it provides a venue for the presentation of ongoing research projects, where researchers invite discussion of preliminary results. Although the TPHOLs conferences have their genesis in meetings of the users of the HOL theorem proving system, each successive year has seen a higher rate of contribution from the other groups with similar goals, particularly the user communities of Coq, Isabelle, Lambda, Lego, NuPrl, and PVS. Since 1993 the proceedings have been published by Springer as volumes in Lecture Notes in Computer Science series. Bibliographic details of these publications can be found at the back of this book; more history of TPHOLs can be found with further information about the 1998 event at http://cs.anu.edu.au/TPHOLs98/.Conference Papers: Integrating TPS with Omega By Christoph Benzmuller and Volker Sorge Some Theorem Proving Aids By Paul E. Black and Phillip J. Windley Verification of the MDG Components Library in HOL By Paul Curzon, Sofiene Tahar, and Otmane Ait Mohamed Simulating Term-Rewriting in LPF and in Display Logic By Jeremy E. Dawson A Prototype Generic Tool Supporting the Embedding of Formal Notations By Andrew M. Gravell and Chris H. Pratten Embedding a Formal Notation: Experiences of Automating the Embedding of Z in the Higher Order Logics of PVS and HOL By Andrew M. Gravell and Chris H. Pratten Building HOL90 Everywhere Easily (Well Almost) By Elsa L. Gunter Program Composition in COQ-UNITY : By Francois Marques Formally Analysed Dynamic Synthesis of Hardware By Kong Woei Susanto and Tom Melham Requirements for a Simple Proof Checker By Geoffrey Watson Integrating HOL and RAISE: a practitioner's approach By Wai Wong and Karl R. P. H. Leung Effective Support for Mutually Recursive Types By Peter V. Homeie

Studies of Volcanic Influence on Aerosols, Clouds and Climate

This thesis focuses on the influence of volcanism on the compositions of the aerosols in the upper troposphere (UT) and lowermost stratosphere (LMS), and their direct and indirect impact on climate. Aerosol data were obtained by aircraft-borne sampling, using the CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) platform, and laboratory-based ion beam analysis of aerosol samples at the Lund Ion Beam Analysis Facility (LIBAF). Aerosol composition data were compared to particle size distributions obtained from onboard optical particle counter (OPC) measurements, demonstrating good agreement between the two analysis systems. The impact on climate was investigated using satellite observations of aerosol and optical properties of cirrus clouds. These were provided by the CALIOP and MODIS instruments onboard the NASA satellites CALIPSO, Terra and Aqua. The aerosol load in the LMS has varied considerably since 2000, mainly due to volcanic injections of particles and particleforming gases. Tropical volcanoes affect the LMS for up to two years after eruption, through transport within the Brewer- Dobson circulation. In contrast, extra-tropical volcanoes inject aerosols directly into the LMS, which subside to the UT within months. The eruption of Kasatochi in August 2008 increased the aerosol load in the northern hemisphere LMS by a factor of ~10. Apart from sulfate and ash, both fresh and aged volcanic aerosols contain surprisingly large amounts of carbonaceous aerosols, and the value of the oxygen:carbon ratio (O/C) of ~2 indicates an organic origin. Entrainment of the organic aerosol present in the tropospheric background within volcanic jets and plumes was suggested to be the cause. Using CALIOP data, it was shown that the stratospheric aerosol at altitudes below 15 km constitutes a significant part of the volcanic forcing. During the period from 2008 to the middle of 2012, volcanic forcing in the LMS constituted 30% of that in the rest of the stratosphere. In addition, volcanism was found to have a significant influence on aerosol concentrations in the UT of the northern hemisphere. Comparison with cirrus reflectance (CR) data obtained using the MODIS instrument revealed a strong anti-correlation between the CR and particulate sulfur mass concentration, suggesting that the volcanic aerosol affected midlatitude cirrus clouds. In 2011, the CR was 8% lower than in 2001. Since cirrus clouds warm the Earth, this decrease is associated with regional cooling. The results of these studies show that previous estimates of the impact of volcanism on climate have been underestimated. The investigations of the direct and indirect radiative effects of volcanism on the UT and LMS presented here provide new information on the effect of volcanism on the Earth’s climate. This will allow more realistic estimates of the impact of volcanism on climate variability, and improve climate models providing more realistic projections of future global temperatures