Hartmut Graßl

Welt im Wandel : Energiewende zur Nachhaltigkeit

Das Recht der Entwicklungsl nder auf Entwicklung und die Erhaltung der nat rlichen Lebensgrundlagen sind die wesentlichen Herausforderungen bei einer Energiewende zur Nachhaltigkeit und der Ausgangspunkt des vorliegenden Gutachtens. Wenn die Politik sofort entschieden handelt, ist die Transformation der globalen Energiesysteme ohne gravierende Einschr nkungen m glich und finanzierbar: Die Energieeffizienz muss gesteigert, der Anteil fossiler Energietr ger deutlich verringert und die erneuerbaren Energien massiv gef rdert werden. F r den Einstieg in das Solarzeitalter hat der Wissenschaftliche Beirat der Bundesregierung Globale Umweltver nderungen (WBGU) einen Fahrplan mit konkreten Zielen und Ma nahmen entwickelt.

Numerical modelling of transspectral processes in natural waters: implications for remote sensing

Based on a previously developed and thoroughly validated hydrooptical model, numerical simulations of the spectral composition of water leaving radiance are presented. These simulations take into account absorption, elastic scattering, water Raman (inelastic) scattering as well as the fluorescence of chlorophyll ( chl ) and dissolved organics ( doc ). The results obtained for forward modelling were also used for the inverse problem: retrieval of water quality parameters from water volume reflectance ( R ) spectra. The Levenberg-Marquardt multivariate optimization procedure was used for this purpose. Unlike water Raman scattering, the chl and doc fluorescence has an impact on R, so the retrieval results can change substantially for waters rich in chl or doc . Suspended minerals ( sm ) suppress both the chl and doc fluorescence influence on R . The retrieval results indicate that chl can be accurately assessed if the concentration of sm is not low and the doc concentration is < 2 mgCl -1 . For waters devoid of doc, the concentration of chl can be accurately retrieved even if the sm concentration is very low. Retrieval errors prove to be strongly dependent on the fluorescence yield value of both chl and doc .

Climate and Environment

Homo sapiens, as the dominating species, has to use its progress in technology for sustainable development. The prerequisite is a basic understanding of the functioning of the Earth system. This understanding needs global continuous data, i.e., it needs satellite remote sensing or earth observation from space. It also needs Earth system models, whose development stage is just a measure of the sophistication of validation data sets. Thus satellite remote sensing is at the heart of progress in understanding and therefore acts not only as an early warning system for mankind but also offers problem solutions through better understanding.

Navigation of satellite measurements without ground control points

Abstract The minimum of information on satellite dynamics (a part of celestial mechanics) which is needed to navigate operational polar orbiting meteorological satellites either for direct or inverse referencing without ground control points, is presented. This software is tailored to the orbit information available. Its validation by ground control points is also included. The accuracy achieved by the improved software in the determination of the time of satellite culmination over a pixel (or pixel line) and in the off-nadir angle (or pixel number) is comparable to the pixel size (1–5 km) of the AVHRR onboard NOAA-N satellites, if the standard orbital elements are not older than about two weeks.

Remote sensing of coastal waters by airborne lidar and satellite radiometer Part 1: A model study

Abstract Radiative transfer calculations for remote sensing of coastal waters by airborne lidar and satellite radiometer have been compared in order to answer the question, whether an airborne lidar may be used instead of in situ measurements from ships to calibrate a satellite radiometer. The radiative transfer of laserlight measuring the Raman-scattering of water molecules, the fluorescence of chlorophyll-a and the fluorescence of yellow substance or Gelbstoff is simulated by the lidar equations while the radiance to a satellite radiometer is calculated with an ocean-atmosphere model based on the matrix-operator method. Including multiple scattering in the lidar equations, an eigenvalue analysis shows that three oceanic constituents (chlorophyll-a, nonchlorophyllous particles and Gelbstoff) can be separated measuring the backscattered laserlight at three wavelengths from a height of 100 to 200m. Changes in the concentration of all three substances are detected with higher accuracy with an airborne lidar...

Special issue: 125 years of high-mountain research at Sonnblick Observatory (Austrian Alps)

It was in 1886 when the Sonnblick Observatory, in the Austrian Alps, was built through the fortunate circumstances that the idea of meteorologist Julius Hann was brought into practice by the local gold miner Ignaz Rojacher (Fig. 1). This was at a time when people thought that it is impossible to survive the harsh winter months with the extreme climate conditions at such elevations. Until today everyday live at the observatory has changed significantly. It moved to an outstanding research platform with cable car access, power supply, internet connection, etc., but it is still remote—not only for people but also from local pollution sources, which makes it an ideal place for environmental research (Fig. 2). The celebration of the 125th anniversary was not only a ceremonial act at the observatory but also the occasion for an international conference on “Climate Change in High Mountain Regions” in the City of Salzburg in September 2011. The response to the announcement of the conference was overwhelming, thus indicating the high relevance of this topic in climate research. In particular, the high interest was not only triggered from the subject of the conference in general, but also from the unique role of the mountain observatories they play in studies on process understanding of climate change based on long-termmeasurements. On the one hand side, the success of the Salzburg conference was due to the high level of scientific contributions from participants at international level. On the other hand, the conference got substantial financial support from the Austrian Federal Ministry of Science and Research and from the Mountain Research Initiative (based in Switzerland). The authors of the most outstanding presentations of the Salzburg Conference were invited by the editors to submit an article for this special issue of TAC. All the articles went through the normal reviewing process of the journal.

The Global Distribution of Aerosols

The radiation budget of planet Earth, given the solar irradiance at the top of the atmosphere, is to a large extent determined by minor constituents of the atmosphere. Less than three thousandths of its mass – including water vapour, cloud water and cloud ice – regulate how much solar radiation reaches the surface and from where in the atmosphere or on the surface the same amount of energy as absorbed globally from solar irradiance is radiated back to space in the thermal infrared. The least understood part of the Earth’s radiation budget and its changes is related to an extremely small fraction of the minor constituents, the aerosol particles, liquid or solid particles suspended in air in the size range from about a nanometer to a few micrometers. At a typical mass mixing ratio of 10 μg/m3 in the free troposphere aerosol particles constitute only about 10−10 of the mass or 10−13 of the volume fraction of tropospheric air.

The atmospheric boundary layer - Special issue honouring the memory of Hans Hinzpeter

The colloquium on “The atmospheric boundary layer” was held in Hamburg from February 12 to 13, 2001 and was organized by the Max Planck Institute for Meteorology in cooperation with the Meteorological Institute of the University of Hamburg. The event was organised to honour the memory of Prof. Dr. Hans Hinzpeter, distinguished meteorologist, teacher, administrator and science policy maker. Prof. Hinzpeter was the former director of the Meteorological Institute of the University of Hamburg and director at the Max Planck Institute for Meteorology. The colloquiumwas held on the occasion of the first anniversary of his death (December 15, 1999) and of his 80th birthday (January 31, 2001). Although Prof. Hinzpeter’s range of interests was legendary, the colloquium focused on the atmospheric boundary layer because during Hinzpeter’s era in Hamburg the understanding of convective and turbulent processes in the marine boundary layer was substantially pushed as a result of the numerous field experiments organised by himself. The aim of the colloquium was to give, on the basis of recent observational and modelling studies, an overview of the advances in the level of knowledge of clear and cloudy boundary layers, as provided by former students and close collaborators of Hans Hinzpeter. During the last decades major efforts went into the understanding of the atmospheric boundary layer. Initially much emphasis was given on the clear convective and shear driven boundary layer and studies were predominantly concerned with questions of how much momentum, heat, moisture and air pollutants are transported by turbulent motions and how do these turbulent eddies interact with each other and with the thermal inversion which is capping the atmospheric boundary layer. A better fundamental understanding of these questions became even more relevant for a cloudy atmospheric boundary layer. Therefore, in the last decade the field has expanded with numerous studies on turbulence and boundary layer clouds on different scales. These studies have provided updated theories and concepts, through the combined efforts of observational campaigns, high-resolution modelling, evaluation and impact studies. From a practical perspective, a better understanding of turbulence in the atmospheric boundary layer had served to improve the parameterisation of boundary-layer processes in large-scale climate and weather prediction models. The special issue is organised in three parts. Part 1 contains a historical review focusing on different steps of the professional career of Prof. Hinzpeter. Part 2 covers five papers on observational studies utilizing in-situ instruments as well as remote sensing devices like lidar, radar and sodar in order to study the mean state and turbulence structure of the boundary layer. Part 3 contains three papers on modelling studies ranging from a small-scale large-eddy simulation of the cloud-topped boundary layer to the application of boundary layer knowledge for meso-scale modelling including environmental and air-quality research issues. Finally, we would like to thank all the speakers and participants at the meeting for their contributions and suggestions. We also thank the Max Planck Society for the financial support to the colloquium which also allowed an effective exchange of ideas and interaction among experimentalists and modellers working on various aspects of the atmospheric boundary layer.

Modellierung anthropogener und natürlicher Klimaänderungen

The delay of anthropogenic climate change caused by oceans and other slowly reacting climate system components forces us to numerical modeling as the basis of decisions. For three three-dimensional numerical examples, namely transient coupled ocean-atmosphere models for the additional greenhouse effect, internal ocean-atmosphere variability, and disturbance by soot particles from burning oil wells, the present-day status is described. From all anthropogenic impacts on the radiative balance, the contribution from trace gases is the most important. D as Wissen um Klimafinderungen, in der Vergangenheit, bevorstehend oder bereits angelaufen, die auch vom Menschen verursacht sind, hat in den letzten Jahren rasch zugenommen. Trotzdem besteht je nach Informationsstand oder pers6nlichem Skeptizismus noch immer groge Unsicherheit fiber die grogr/~umige Auspr/~gung einer anthropogenen Klima~inderung. Oft werden die Zeitskalen durcheinander geworfen, die Tr~igheit mancher Klimasystemkomponenten wird mif3achtet, oder ein Detail wie die CO2-Dtingung wird aufgebauscht. Im folgenden wird versucht, den gegenw/irtigen Stand der numerischen Modellierung an einigen Beispielen klarzumachen, wobei bewugt kurzfristige und teilweise regionale Ph~inomene, wie eine Aerosolbelastung der Atmosphfire, 1/~ngerfristigen globalen, wie dem zus~itzlichen Treibhauseffekt, und sfikularen Schwankungen, wie der Salzgehaltsschwingung des Atlantiks, gegenfibergestellt werden.