Search results for " layer"
showing 10 items of 1022 documents
Aerosol closure study by lidar, sun photometry, and airborne optical counters during DAMOCLES field campaign at El Arenosillo sounding station, Spain
2011
We present a comparison of aerosol properties derived from in situ and remote sensing instruments during DAMOCLES campaign, aimed at investigating the equivalence between the instrumentation and methodologies employed by several Spanish groups to study atmospheric aerosols at a regional background site. The complete set of instruments available during this closure experiment allowed collecting a valuable high-resolution aerosol measurement data set. The data set was augmented with airborne in situ measurements carried out in order to characterize aerosol particles during the midday of 29 June 2006. This work is focused on aerosol measurements using different techniques of high-quality instr…
The impact of a mesoscale convective system cold pool on the northward propagation of the intertropical discontinuity over West Africa
2009
The interaction between a mesoscale convection system cold pool and the intertropical discontinuity (ITD) is investigated on two consecutive days (5 and 6 June 2006), in the framework of the African Monsoon Multidisciplinary Analysis Special Observing Period (SOP 1a). Satellite imagery and surface meteorological observations are used to track the movement of the ITD prior to and after its interaction with the cold pool. The impact of the northward propagating cold pool on the Sahelo-Saharan planetary boundary layer (PBL) thermodynamics and aerosol vertical distribution is analyzed by means of airborne and ground-based measurements over the two-day period. Complementary European Centre for M…
Northward bursts of the West African monsoon leading to rainfall over the Hoggar Massif, Algeria
2009
The Hoggar Massif is a comparatively populated region in the Sahara, where water supply is a critical problem due to the lack of nearby sources and unaffordable water pumping. In the present paper, we analyse the influence of the West African monsoon (WAM) on precipitation over the Hoggar during summer. We investigate (1) two rainfall events during 23-27 July 2006, accounting for almost half of the precipitation of this year, and (2) the representativity of this period with regard to ERA-40 ECMWF re-analyses (1979 to 2001). By the end of July 2006, two consecutive northward bursts of the WAM flow reached the Hoggar and caused an increase in low-level humidity. In the afternoon of these days…
Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker <i>Amundsen</i> from …
2016
Abstract. Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned dist…
A Precise Photometric Ratio via Laser Excitation of the Sodium Layer II: Two-photon Excitation Using Lasers Detuned from 589.16 nm and 819.71 nm Reso…
2020
This article is the second in a pair of articles on the topic of the generation of a two-color artificial star (which we term a "laser photometric ratio star," or LPRS) of de-excitation light from neutral sodium atoms in the mesosphere, for use in precision telescopic measurements in astronomy and atmospheric physics, and more specifically for the calibration of measurements of dark energy using type Ia supernovae. The two techniques respectively described in both this and the previous article would each generate an LPRS with a precisely 1:1 ratio of yellow (589/590 nm) photons to near-infrared (819/820 nm) photons produced in the mesosphere. Both techniques would provide novel mechanisms f…
Atomic layer deposition of polyimide thin films
2007
The atomic layer deposition (ALD) of different polyimide thin films has been studied. We have demonstrated self-limiting ALD deposition of PMDA–DAH, PMDA–EDA, PMDA–ODA and PMDA–PDA thin films at 160 °C. The maximum deposition rate of 5.8 A cycle−1 was obtained for the PMDA–DAH process. Although the deposition rate was high at 160 °C, a sudden decrease was observed when the temperature was increased. Regardless of the process studied, no film growth was obtained at 200 °C or above. Deposited polyimide films were analysed by FTIR, AFM and TOF-ERDA. According to the FTIR measurements, imide bonds were formed already in as-deposited films indicating polyimide formation without any additional th…
Thin Film Characterisation Using MeV Ion Beams
2009
This chapter focuses on the characterisation of very thin films having thicknesses from a few nanometres to tens of nanometres. The driving force for the ion beam analysis community has mostly been the rapid development of microelectronics — all the elements in new thin SiO2 replacing dielectrics, diffusion barriers, and silicide contacts need to be analysed with a depth resolution even better than a nanometre. This together with new film deposition techniques like atomic layer deposition (ALD) [1] have given a push to the ion beam analysis community to develop new and better techniques using energetic (>0.5 MeV) ion beams.
A theoretical investigation on the Cd doping of Cu-depleted CuInSe<inf>2</inf> materials
2011
Because of their outstanding characteristics and affordable price, polycrystalline thin film solar cells based on CuIn 1−x Ga x Se 2 (CIGS) absorber layer have emerged to be one of the most promising materials for photovoltaic applications [1–2]. To further enhance the efficiency of these solar cells much effort is spent on the in-depth investigation of the production methods. However, the effect of structural defects and dopants upon the macroscopic properties and morphology of epitaxially grown CIGS films is not yet fully understood [3]. More importantly, it is well established that the best cells can be prepared by growing the CIGS absorber layer under Cu-poor conditions [4]. Thus, it is…
Influence of the passive film properties and residual stresses on the micro-electrochemical behavior of duplex stainless steels
2010
In the present paper, the chemical composition of passive films formed on both phases of two types of duplex stainless steels (UNS S31803 and UNS S32304) is determined at the micro-scale using Auger electron spectroscopy (AES). Samples were either mechanically polished (down to diamond pastes) or electrochemically etched in acidic solutions. The micro-electrochemical behavior of samples was then determined in sodium chloride media by means of the electrochemical micro-cell technique (capillary diameters of 30 μm). The results obtained were analyzed considering the passive film chemical composition. Quantitative relationships between electrochemical parameters and the distribution of chromiu…
Attacks Against the WAP WTLS Protocol
1999
The WAP WTLS protocol was designed to provide privacy, data integrity, and authentication for wireless terminals. The protocol is currently being fielded, and it is expected that the protocol will be contained in millions of devices in a few years.