Determination and impact of surface radiative processes for TOGA COARE

Experiments using atmospheric general circulation models have shown that the atmospheric circulation is very sensitive to small changes in sea surface temperature in the tropical western Pacific Ocean warm pool region. The mutual sensitivity of the ocean and the atmosphere in the warm pool region places stringent requirements on models of the coupled ocean atmosphere system. At present, the situation is such that diagnostic studies using available data sets have been unable to balance the surface energy budget in the warm pool region to better than 50 to 80 W/sq m. The Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE) is an observation and modelling program that aims specifically at the elucidation of the physical process which determine the mean and transient state of the warm pool region and the manner in which the warm pool interacts with the global ocean and atmosphere. This project focuses on one very important aspect of the ocean atmosphere interface component of TOGA COARE, namely the temporal and spatial variability of surface radiative fluxes in the warm pool region

Analysis of the GOES 6.7 micrometer channel observations during FIRE 2

Clouds form in moist environments. FIRE Phase II Cirrus Implementation Plan (August, 1990) noted the need for mesoscale measurements of upper tropospheric water vapor content. These measurements are needed for initializing and verifying numerical weather prediction models and for describing the environment in which cirrus clouds develop and dissipate. Various instruments where deployed to measure the water vapor amounts of the upper troposphere during FIRE II (e.g. Raman lidar, CLASS sonds and new cryogenic frost hygrometer on-board aircraft). The formation, maintenance and dissipation of cirrus clouds involve the time variation of the water budget of the upper troposphere. The GOES 6.7 mu m radiance observations are sensitive to the upper tropospheric relative humidity, and therefore proved extremely valuable in planning aircraft missions during the field phase of FIRE II. Warm 6.7 mu m equivalent black body temperatures indicate a relatively dry upper troposphere and were associated with regions generally free of cirrus clouds. Regions that were colder, implying more moisture was available may or may not have had cirrus clouds present. Animation of a time sequence of 6.7 mu m images was particularly useful in planning various FIRE missions. The 6.7 mu m observations can also be very valuable in the verification of model simulations and describing the upper tropospheric synoptic conditions. A quantitative analysis of the 6.7 mu m measurement is required to successfully incorporate these satellite observations into describing the upper tropospheric water vapor budget. Recently, Soden and Bretherton (1993) have proposed a method of deriving an upper tropospheric humidity based on observations from the GOES 6.7 mu m observations. The method is summarized in the next section. In their paper they compare their retrieval method to radiance simulations. Observations were also compared to ECMWF model output to assess the model performance. The FIRE experiment provides a unique opportunity to further verify the GOES upper tropospheric relative humidity retrieval scheme by providing (1) aircraft observations to cross-validate the calibration of the GOES 6.7 mu m channel, (2) accurate upper tropospheric water vapor concentrations for verification, and (3) veritical variability of upper tropospheric water vapor

Remote sensing of ice crystal asymmetry parameter using multi-directional polarization measurements – Part 1: Methodology and evaluation with simulated measurements

We present a new remote sensing technique to infer the average asymmetry parameter of ice crystals near cloud top from multi-directional polarization measurements. The method is based on previous findings that (a) complex aggregates of hexagonal crystals generally have scattering phase matrices resembling those of their components; and (b) scattering phase matrices systematically vary with aspect ratios of crystals and their degree of microscale surface roughness. Ice cloud asymmetry parameters are inferred from multi-directional polarized reflectance measurements by searching for the closest fit in a look-up table of simulated polarized reflectances computed for cloud layers that contain individual, randomly oriented hexagonal columns and plates with varying aspect ratios and roughness values. The asymmetry parameter of the hexagonal particle that leads to the best fit with the measurements is considered the retrieved value. For clouds with optical thickness less than 5, the cloud optical thickness must be retrieved simultaneously with the asymmetry parameter, while for optically thicker clouds the asymmetry parameter retrieval is independent of cloud optical thickness. Evaluation of the technique using simulated measurements based on the optical properties of a number of complex particles and their mixtures shows that the ice crystal asymmetry parameters are generally retrieved to within 5%, or about 0.04 in absolute terms. The retrieval scheme is largely independent of calibration errors, range and sampling density of scattering angles and random noise in the measurements. The approach can be applied to measurements of past, current and future airborne and satellite instruments that measure multi-directional polarized reflectances of ice-topped clouds

Feedback Control of Flight Speed to Reduce Unmanned Aerial System Noise

The aim of this initial study is to incorporate an acoustic metric into the flight control system of an unmanned aerial vehicle. This could be used to mitigate the noise impact of unmanned aerial systems operating near residential communities. To incorporate an acoustic metric into a pre-existing flight control system, two things are required: a source noise model, and an acoustic controller. An acoustic model was developed based on Gutin's work to estimate propeller noise. The flight control system was augmented with a controller to reduce propeller noise using feedback control of the commanded flight speed until an acoustic target was met. This control approach focuses on modifying flight speed only, with no perturbation to the trajectory. Multiple flight simulations were performed and the results showed that integrating an acoustic metric into the flight control system of an unmanned aerial system is possible

Novel Characteristics of Valveless Pumping

This study investigates the occurrence of valveless pumping in a fluidfilled system consisting of two open tanks connected by an elastic tube. We show that directional flow can be achieved by introducing a periodic pinching applied at an asymmetrical location along the tube, and that the flow direction depends on the pumping frequency. We propose a relation between wave propagation velocity, tube length, and resonance frequencies associated with shifts in the pumping direction using numerical simulations. The eigenfrequencies of the system are estimated from the linearized system, and we show that these eigenfrequencies constitute the resonance frequencies and the horizontal slope frequencies of the system; 'horizontal slope frequency' being a new concept. A simple model is suggested, explaining the effect of the gravity driven part of the oscillation observed in response to the tank and tube diameter changes. Results are partly compared with experimental findings.Art. no. 22450

National counter-terrorism (C-T) policies and challenges to human rights and civil liberties: Case study of United Kingdom

In the UK the rise post-2005 in “home-grown” terrorism, relying to a significant extent on strikes on soft targets by “self-starters,” means that the search for effective preventive measures remains a continuing concern. Below a number of the preventive counter-terror measures adopted post-9/11, and incrementally strengthened in response to the current threat, are found to fall into three categories and represent interventions at the stages in the path toward attacks. This chapter focuses on selected examples of these preventive measures. In terms of three key stages, firstly, there is the attempt to prevent radicalization, under the “Prevent” strategy. A second strategy relies on taking certain measures to control the activities of those considered likely – on the balance of probabilities – to engage in terrorist-related activity. A third preventive strategy relies on the special terrorism offences under the Terrorism Acts 2000 and 2006, as amended, intended to allow for intervention at a very early stage in terrorist plots and in preparing or instigating terrorist acts (“precursor” offences)

A multicenter evaluation of the efficacy and duration of action of alcaftadine 0.25% and olopatadine 0.2% in the conjunctival allergen challenge model

Background: The purpose of this study was to evaluate the efficacy and duration of action of once-daily dosing with alcaftadine 0.25% ophthalmic solution and olopatadine 0.2% ophthalmic solution as compared with placebo in the prevention of ocular itching, and to directly compare the efficacy of alcaftadine 0.25% with olopatadine 0.2% in the prevention of ocular itching associated with allergic conjunctivitis using the conjunctival allergen challenge model. Methods: Subjects with allergic conjunctivitis (n = 127) were enrolled in a multicenter, double-masked, randomized, active-controlled and placebo-controlled clinical trial. Using the conjunctival allergen challenge model, this study was conducted over the course of approximately 5 weeks. Subjects were randomized into one of three treatment arms: alcaftadine 0.25% ophthalmic solution, olopatadine 0.2% ophthalmic solution, or placebo. Study medications were administered twice over the course of the trial. The primary efficacy measure for the study was ocular itching evaluated by the subject at 3, 5, and 7 minutes post challenge. Secondary endpoints, measured at 7, 15, and 20 minutes post challenge, included conjunctival, ciliary, and episcleral redness, lid swelling, chemosis, and tearing. Duration of action was measured at 16 and 24 hours post-instillation of the study medication at visits 3 and 4, respectively. Results: For the primary measure of ocular itching, both actives, alcaftadine 0.25% and olopatadine 0.2%, were statistically superior to placebo at all three measured time points for both the 16-hour and 24-hour measures (P < 0.0001). Eyes treated with alcaftadine 0.25% had numerically lower mean ocular itching scores than eyes treated with olopatadine 0.2% at every time point, and this difference was statistically significant at the 3-minute time point 16 hours post instillation (P = 0.026). Eyes treated with alcaftadine 0.25% and with olopatadine 0.2% displayed significantly less lid swelling relative to placebo at every time point for the 16-hour and 24-hour post-instillation visits (P < 0.005). Alcaftadine 0.25% was the only active treatment that provided statistically significant relief of chemosis at every time point of the 24-hour post-instillation visit. Conclusion: Both the alcaftadine 0.25% and olopatadine 0.2% ophthalmic solutions provided highly effective relief of ocular itching at both 16 and 24 hours post-instillation. Treatment differences between the actives were most pronounced at the earliest time point (3 minutes post-challenge) following conjunctival allergen challenge (16 hours), when alcaftadine 0.25% ophthalmic solution was statistically superior to olopatadine 0.2% ophthalmic solution. Alcaftadine 0.25% was the only treatment to provide significant relief from chemosis at both 16 and 24 hours post-instillation. Both active treatments and placebo were generally safe and well tolerated

Corruption in migration management: a network perspective

This paper explores the relation between networks as an emerging mode of public governance and corruption. Adopting the theoretical lens of actor-network theory (ANT), the paper investigates an Italian episode of corruption related to the awarding of government contracts for the management of the Mineo’s CARA, the Europe's largest reception centre for migrants. The analysis shows that a governance network may turn corruption itself into a network where abuse of power can proliferate thanks to the opacity resulting from the multiplicity of actors, interactions, and fragmentation characterizing the governance system