Air-sea flux measurements over the Southern Ocean

The Waves, Aerosol, and Gas Exchange Study (WAGES) collected 18 months of near-continuous and autonomous turbulent air-sea flux estimates from the research vessel RRS James Clark Ross. Supporting meteorological and sea-state measurements were also made, with the objective of improving air-sea flux parameterisations. Making turbulence measurements from a ship is technically challenging, due to bias caused by platform motion and airflow distortion. Typically, visual inspection of individual turbulence spectra is needed to quality control eddy covariance flux estimates; for WAGES the sheer volume of data motivated the development of an automated quality control method, to be performed on individual flux cospectra. The application of these tests allowed a robust relationship between the 10 m wind speed and the neutral drag coefficient to be developed, which had previously not been achieved with ship-based covariance measurements alone. This parameterisation is toward the higher end of the range of accepted values, and indicates some wind speed dependence of the Charnock parameter, rather than it being a constant. A detailed investigation of turbulent flow distortion was made; insights into the physics were gained, and a novel correction method for motion-correlated flow distortion was developed and validated. Two major modes of motion-correlated flow distortion of the turbulence were found: one correlated to the pitch, acknowledge in the literature; a second and more powerful mode correlated to the rate of change of the pitch, not acknowledged in any publication. The quality control and bias correction techniques developed for the momentum fluxes were transferred to a preliminary investigation of the sensible and latent heat fluxes. The uncertainty in the latent heat transfer coefficient was reduced considerably by use of the new techniques; however the sensible heat fluxes were dominated by noise, so discarded. The methods and corrections developed in this thesis could be used to reanalyse the turbulent flux measurements from many ship-based campaigns; improving our understanding of the physics of air-sea exchange without need for additional expensive measurements

Observations of the Temperature and Humidity Structure Parameter Over Heterogeneous Terrain by Airborne Measurements During the LITFASS-2003 Campaign

The turbulent structure parameters of temperature ((Formula presented.)) and humidity ((Formula presented.)), and their cross-structure parameter ((Formula presented.)), are investigated using data collected with the airborne-measurement platform Helipod during the LITFASS-2003 campaign. The flights took place within the atmospheric surface layer over heterogeneous terrain including forests, a lake and farmland. We find variability in (Formula presented.) along such flight legs, with values of (Formula presented.) over forested surfaces one order of magnitude larger than over farmland, and two orders of magnitude larger than over the lake. However, a quantitative relationship between the magnitude of (Formula presented.) and the surface type is not found, most likely due to a similar surface latent heat flux between the land-use types. However, when the different flight legs are taken together and data grouped by land-use type, values of (Formula presented.) are significantly lower over the lake than over the other surfaces. A classification of (Formula presented.) is only possible between water and land surfaces, with lower values over water. We find the correlation coefficient (Formula presented.) in the range of 0.4–1.0, which is less than unity, and thus violates the assumption of unity in Monin–Obukhov similarity theory.</p

Zur Wirksamkeit von Finanzsanktionen als Instrument im Kampf gegen den Terrorismus

Bereits vor dem 11. September 2001 wurde damit begonnen, Finanzmittel als Instrument im Kampf gegen den Terrorismus einzusetzen. Danach wurden sie zumindest zeitweilig als besonders effektiv angesehen, um den Aktionsradius transnationaler terroristischer Gruppen einzuschränken. Allerdings gibt es wenig fundierte Untersuchungen der Wirksamkeit der gegen den Terrorismus eingesetzten Instrumente wie das Einfrieren von Aktiva und die Erhöhung der Transparenz internationaler Finanztransaktionen. Ein wesentlicher Grund dafür sind der Mangel an belastbaren Daten, ein anderer die grundsätzlichen Probleme der Untersuchung der kausalen Wirkung von begrenzten Politikmaßnahmen. In diesem Beitrag wird zunächst, als Grundlage für intendierte Wirkungen, die Umsetzung von Maßnahmen gegen Terrorfinanzierung (Einfrieren von Finanzaktiva, Erhöhung der Transparenz, weltweite Umsetzung der Maßnahmen) betrachtet. Danach werden vorliegende Informationen und Daten über terroristische Anschläge auf Hinweise auf die Wirkung von Finanzsanktionen, einschließlich von Substitutionseffekten, untersucht. Die belegbare Effektivität von Finanzsanktionen wird allerdings durch hohe indirekte Kosten nichtintendierter Nebenwirkungen hingegen relativiert. Abstract Already before September 11, 2001, financial measures were used as instruments of counterterrorism. After that, they were seen, at least for some time, as particularly effective in limiting the activities of transnational terrorist groups. Unfortunately, there is little well-gounded research on the effectiveness of financial sanctions, including the freezing of financial assets and the increase on transparency of international financial transactions. A main reason is the lack of reliable data, another are the fundamental problems of investigating the causal links of limited policy measures. This contribution begins with a brief assessment of the implementation of major common measures against terrorist financing (freezing of assets, increased transparency over financial transactions, worldwide acceptance of measures). In the following sections, the available information and data of terrorist incidences is analyzed. Effect of financial sanctions can be demonstrated. However, the data also indicates substitution effects. Furthermore, the efficiency of demonstrable direct effects of financial sanctions is called into question by high indirect costs of unintentional effects. JEL Classifications: F51, F33, G3