Hasil untuk "Earthwork. Foundations"

N. Aoki, N. Aoki, N. Aoki et al.

<p>The CO<span class="inline-formula">₂</span> molar fraction in standard gas mixtures is known to deviate as a result of adsorption/desorption to/from the inner surface of a high-pressure cylinder and thermal diffusion fractionation caused by the temperature distribution in the cylinder. This deviation reduces the consistency of atmospheric CO<span class="inline-formula">₂</span> observations, because the standard gas mixtures are used to calibrate all measurement systems for precise CO<span class="inline-formula">₂</span> observations. To maintain the consistency of CO<span class="inline-formula">₂</span> values over the long term, a quantitative understanding of the deviations in the CO<span class="inline-formula">₂</span> molar fraction in a standard gas mixture is needed. Thus far, this understanding has not been achieved sufficiently well, because the contribution of thermal diffusion fractionation is less well understood than that of adsorption/desorption. In this study, offsets of 0.013 <span class="inline-formula">±</span> 0.015 and <span class="inline-formula">−</span>0.014 <span class="inline-formula">±</span> 0.011 <span class="inline-formula">µmol</span> mol<span class="inline-formula">⁻¹</span> were observed in the outflowing gas from horizontally and vertically positioned cylinders, respectively, at a flow rate of 0.080 L min<span class="inline-formula">⁻¹</span>. These offsets are attributed to thermal diffusion effects, which diluted and enriched the CO<span class="inline-formula">₂</span> molar fraction by <span class="inline-formula">−</span>0.045 <span class="inline-formula">µmol</span> mol<span class="inline-formula">⁻¹</span> (horizontal cylinder) and 0.048 <span class="inline-formula">µmol</span> mol<span class="inline-formula">⁻¹</span> (vertical cylinder) as the relative pressure dropped to 0.03. In the experiments at same flow rate, the adsorption/desorption effect enriched the CO<span class="inline-formula">₂</span> molar fraction by 0.06 <span class="inline-formula">µmol</span> mol<span class="inline-formula">⁻¹</span> (horizontal cylinder) and 0.10 <span class="inline-formula">µmol</span> mol<span class="inline-formula">⁻¹</span> (vertical cylinder). Therefore, attention should be paid to both thermal diffusion fractionation and adsorption/desorption effects for precise calibration of long-term observations of CO<span class="inline-formula">₂</span> molar fractions, although past studies have ignored the contribution of thermal diffusion fractionation at the low flow rates (<span class="inline-formula">&lt;</span> 0.3 L min<span class="inline-formula">⁻¹</span>) examined in this study. Furthermore, the deviation of the CO<span class="inline-formula">₂</span> molar fraction depends only on the pressure relative to the initial pressure of the cylinder. This result suggests that the recommendation by the World Meteorological Organization (WMO) to replace the standard gas mixture once the cylinder pressure drops to 2 MPa needs to be revised.</p>

K. Ośródka, J. Szturc, A. Jurczyk et al.

<p>Rain gauge measurements are one of the primary techniques used to estimate a precipitation field, but they require careful quality control. This paper describes a modified RainGaugeQC system, which is applied to real-time quality control of rain gauge measurements made every 10 min. This system works operationally at the national meteorological and hydrological service in Poland. The RainGaugeQC algorithms, which have been significantly modified, are described in detail. The modifications were made primarily to control data from non-professional measurement networks, which may be of lower quality than professional data, especially in the case of personal stations. Accordingly, the modifications went in the direction of performing more sophisticated data control, applying weather radar data, and taking into account various aspects of data quality, such as consistency analysis of data time series and bias detection. The effectiveness of the modified system was verified based on independent measurement data from manual rain gauges, which are considered one of the most accurate measurement instruments, although they mostly provide daily totals. In addition, an analysis of two case studies is presented. This highlights various issues involved in using non-professional data to generate multi-source estimates of the precipitation field.</p>

B. Jahani, B. Jahani, B. Jahani et al.

<p>This study presents an algorithm for the detection of fog and low stratus (FLS) over Europe based on the infrared bands of the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) instrument on board the Meteosat Second Generation geostationary satellites. As the method operates based on the SEVIRI infrared observations only, it is expected to be stationary in time and thus can provide a coherent and detailed view of FLS development over large areas over the 24 h day cycle. The algorithm is based on a gradient boosted tree machine learning model that is trained with ground truth observations from METeorological Aerodrome Report (METAR) stations and the SEVIRI observations at bands centered at 8.7, 10.8, 12.0, and 13.4 <span class="inline-formula">µ</span>m wavelengths. The METAR data used here comprise a total number of 2 544 400 data points spread over the winters (i.e., 1 September to 31 May) of the years 2016–2022 and 356 locations across Europe. Among them, the data points corresponding to 276 stations and the winters of 2016–2018 and 2019–2021 (<span class="inline-formula">∼</span> 45 % of all data points) were used to train the algorithm. The remaining data points comprise four independent datasets which were used to validate the algorithm's performance and applicability to time spans and locations within the study area (i.e., Europe) that extend beyond those covered by the data points used for the algorithm training, as well as to compare the algorithm's accuracy at the locations of METAR stations with that of the existing state-of-the-art daytime FLS detection algorithm Satellite-based Operational Fog Observation Scheme (SOFOS). Validation of the algorithm against the METAR data showed that the algorithm is well suited for the detection of FLS. Specifically, the algorithm is found to detect FLS with probability of detection (POD) values ranging from 0.70 to 0.82 (for different inter-comparison approaches) and false alarm ratios (FARs) between 0.21 and 0.31. These numbers are very close to those achieved by SOFOS for differentiating FLS from other sky conditions at the tested locations and time spans. These results also showed that the technique's applicability in the study region extends beyond the particular locations and time spans covered by the data points used for training the algorithm.</p>

B. W. Forgan, J. Gröbner, I. Reda

<p>An equation for the Absolute Cavity Pyrgeometer (ACP) is derived from application of Kirchhoff's law and the addition of a convection term to account for the thermopile being open to the environment, unlike a domed radiometer. The equation is then used to investigate four methods to characterise key instrumental parameters using laboratory and field measurements. The first uses solar irradiance to estimate the thermopile responsivity, the second uses a minimisation method that solves for the thermopile responsivity and transmission of the cavity, and the third and fourth revisit the Reda et al. (2012) linear least squares calibration technique. Data were collected between January and November 2020, when the ACP96 and two IRIS radiometers monitoring terrestrial irradiances were available. The results indicate good agreement with IRIS irradiances using the new equation. The analysis also indicates that while the thermopile responsivity, concentrator transmission and emissivity of an ACP can be determined independently, as an open instrument, the impact of the convection term is minor in steady-state conditions but significant when the base of the instrument is being subjected to rapid artificial cooling or heating. Using laboratory characterisation of the transmission and emissivity, together with use of an estimated solar calibration of the thermopile, generated mean differences of less than 1.5 Wm<span class="inline-formula">⁻²</span> to the two IRIS radiometers. A minimisation method using each IRIS radiometer as the reference also provided similar results, and the derived thermopile responsivity was within 0.3 <span class="inline-formula">µ</span>V W<span class="inline-formula">⁻¹</span> m<span class="inline-formula">²</span> of the solar-calibration-derived infrared responsivity estimate of 10.5 <span class="inline-formula">µ</span>V W<span class="inline-formula">⁻¹</span> m<span class="inline-formula">²</span> estimated using a nominal solar calibration and provide irradiances within <span class="inline-formula">±2</span> % of the terrestrial irradiance measured by the reference pyrgeometers traceable to the International System of Units (SI). The calibration method using linear least squares regression introduced by Reda et al. (2012) that relies on rapid cooling of the ACP base but utilising the new equation was found to produce consistent results but was dependent on the assumed temperature of the air above the thermopile. This study demonstrates the potential of the ACP as another independent reference radiometer for terrestrial irradiance once the magnitude of the convection coefficient and any potential variations in it have been resolved.</p>

Dayou Gao

Titi Sari Nurul Rachmawati, Hyung Cheol Park, Sunkuk Kim

Risks are involved in every aspect of earthwork projects. This paper specifically discusses the cost risk associated with the volume calculation of such projects. In the design phase, it is not possible to accurately predict the quantity per soil type underground of the site. As a result, there are uncertainties in the excavation cost that may cause cost overrun. There is a need for an innovative method to forecast, control, monitor, and manage excavation cost from design phase to completion. There is, however, an innovative method for calculating volume accurately using a digital surface model method. The digital surface model can be acquired using GPS and unmanned aerial vehicles (UAV). This paper proposes a simulation model which is able to analyze, control, and monitor the cost based on excavation volume so stakeholders are able to gain the actual volume quickly and accurately. Monte Carlo simulation is applied to the excavation volume per soil type, resulting in a range of possible outcomes for excavation cost. The developed model was verified by applying it to an actual case project. Throughout the project, the cost was successfully monitored and maintained below the maximum expected cost. However, the final actual cost in the last simulation almost reached the maximum expected cost, indicating the need for cost monitoring. By periodically comparing the simulation result to the actual excavated volume obtained from the UAV, the proposed model can assist stakeholders in controlling the cost overrun risk and developing strategies during the earthwork life cycle.

Z. S. Mir, M. Jamieson, N. R. Greenall et al.

<p>The chemistry and reaction kinetics of reactive species dominate changes to the composition of complex chemical systems, including Earth's atmosphere. Laboratory experiments to identify reactive species and their reaction products, and to monitor their reaction kinetics and product yields, are key to our understanding of complex systems. In this work we describe the development and characterisation of an experiment using laser flash photolysis coupled with time-resolved mid-infrared (mid-IR) quantum cascade laser (QCL) absorption spectroscopy, with initial results reported for measurements of the infrared spectrum, kinetics, and product yields for the reaction of the <span class="inline-formula">CH₂OO</span> Criegee intermediate with <span class="inline-formula">SO₂</span>. The instrument presented has high spectral (<span class="inline-formula">&lt;</span> 0.004 cm<span class="inline-formula">⁻¹)</span> and temporal (<span class="inline-formula">&lt;</span> 5 <span class="inline-formula">µ</span>s) resolution and is able to monitor kinetics with a dynamic range to at least 20 000 s<span class="inline-formula">⁻¹</span>. Results obtained at 298 K and pressures between 20 and 100 Torr gave a rate coefficient for the reaction of <span class="inline-formula">CH₂OO</span> with <span class="inline-formula">SO₂</span> of (3.83 <span class="inline-formula">±</span> 0.63) <span class="inline-formula">×</span> 10<span class="inline-formula">⁻¹¹</span> cm<span class="inline-formula">³</span> s<span class="inline-formula">⁻¹</span>, which compares well to the current IUPAC recommendation of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mrow><mfenced close=")" open="("><mrow><msubsup><mn mathvariant="normal">3.70</mn><mrow><mo>-</mo><mn mathvariant="normal">0.40</mn></mrow><mrow><mo>+</mo><mn mathvariant="normal">0.45</mn></mrow></msubsup></mrow></mfenced></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="58pt" height="22pt" class="svg-formula" dspmath="mathimg" md5hash="d583b63ae9fb740190bf16448b830808"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-2875-2022-ie00001.svg" width="58pt" height="22pt" src="amt-15-2875-2022-ie00001.png"/></svg:svg></span></span> <span class="inline-formula">×</span> 10<span class="inline-formula">⁻¹¹</span> cm<span class="inline-formula">³</span> s<span class="inline-formula">⁻¹</span>. A limit of detection of 4.0 <span class="inline-formula">×</span> 10<span class="inline-formula">⁻⁵</span>, in absorbance terms, can be achieved, which equates to a limit of detection of <span class="inline-formula">∼</span> 2 <span class="inline-formula">×</span> 10<span class="inline-formula">¹¹</span> cm<span class="inline-formula">⁻³</span> for <span class="inline-formula">CH₂OO</span>, monitored at 1285.7 cm<span class="inline-formula">⁻¹</span>, based on the detection path length of (218 <span class="inline-formula">±</span> 20) cm. Initial results, directly monitoring <span class="inline-formula">SO₃</span> at 1388.7 cm<span class="inline-formula">⁻¹</span>, demonstrate that <span class="inline-formula">SO₃</span> is the reaction product for <span class="inline-formula">CH₂OO</span> <span class="inline-formula">+</span> <span class="inline-formula">SO₂</span>. The use of mid-IR QCL absorption spectroscopy offers significant advantages over alternative techniques commonly used to determine reaction kinetics, such as laser-induced fluorescence (LIF) or ultraviolet absorption spectroscopy, owing to the greater number of species to which IR measurements can be applied. There are also significant advantages over alternative IR techniques, such as step-scan FT-IR, owing to the coherence and increased intensity and spectral resolution of the QCL source and in terms of cost. The instrument described in this work has potential applications in atmospheric chemistry, astrochemistry, combustion chemistry, and in the monitoring of trace species in industrial processes and medical diagnostics.</p>

Z. Zhang, E. D. Sherwin, D. J. Varon et al.

<p>Sentinel-2 satellite imagery has been shown by studies to be capable of detecting and quantifying methane emissions from oil and gas production. However, current methods lack performance calibration with ground-truth testing. This study developed a multi-band–multi-pass–multi-comparison-date methane retrieval algorithm that enhances Sentinel-2 sensitivity to methane plumes. The method was calibrated using data from a large-scale controlled-release test in Ehrenberg, Arizona, in fall 2021, with three algorithm parameters tuned based on the true emission rates. Tuned parameters are the pixel-level concentration upper-bound threshold during extreme value removal, the number of comparison dates, and the pixel-level methane concentration percentage threshold when determining the spatial extent of a plume. We found that a low value of the upper-bound threshold during extreme value removal can result in false negatives. A high number of comparison dates helps enhance the algorithm sensitivity to the plumes in the target date, but values in excess of 12 d are neither necessary nor computationally efficient. A high percentage threshold when determining the spatial extent of a plume helps enhance the quantification accuracy, but it may harm the yes/no detection accuracy. We found that there is a trade-off between quantification accuracy and detection accuracy. In a scenario with the highest quantification accuracy, we achieved the lowest quantification error and had zero false-positive detections; however, the algorithm missed three true plumes, which reduced the yes/no detection accuracy. In contrast, all of the true plumes were detected in the highest detection accuracy scenario, but the emission rate quantification had higher errors. We illustrated a two-step method that updates the emission rate estimates in an interim step, which improves quantification accuracy while keeping high yes/no detection accuracy. We also validated the algorithm's ability to detect true positives and true negatives in two application studies.</p>

T. Flament, D. Trapon, A. Lacour et al.

<p>Aeolus carries the Atmospheric LAser Doppler INstrument (ALADIN), the first high-spectral-resolution lidar (HSRL) in space. Although ALADIN is optimized to measure winds, its two measurement channels can also be used to derive optical properties of atmospheric particles, including a direct retrieval of the lidar ratio.</p> <p>This paper presents the standard correct algorithm and the Mie correct algorithm, the two main algorithms of the optical properties product called the Level-2A product, as they are implemented in version 3.12 of the processor, corresponding to the data labelled Baseline 12. The theoretical basis is the same as in <span class="cit" id="xref_text.1"><a href="#bib1.bibx13">Flamant et al.</a> (<a href="#bib1.bibx13">2008</a>)</span>. Here, we also show the in-orbit performance of these algorithms. We also explain the adaptation of the calibration method, which is needed to cope with unforeseen variations of the instrument radiometric performance due to the in-orbit strain of the primary mirror under varying thermal conditions. Then we discuss the limitations of the algorithms and future improvements.</p> <p>We demonstrate that the L2A product provides valuable information about airborne particles; in particular, we demonstrate the capacity to retrieve a useful lidar ratio from Aeolus observations. This is illustrated using Saharan dust aerosol observed in June 2020.</p>

S. Kremser, J. S. Tradowsky, J. S. Tradowsky et al.

Upper-air measurements of essential climate variables (ECVs), such as temperature, are crucial for climate monitoring and climate change detection. Because of the internal variability of the climate system, many decades of measurements are typically required to robustly detect any trend in the climate data record. It is imperative for the records to be temporally homogeneous over many decades to confidently estimate any trend. Historically, records of upper-air measurements were primarily made for short-term weather forecasts and as such are seldom suitable for studying long-term climate change as they lack the required continuity and homogeneity. Recognizing this, the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) has been established to provide reference-quality measurements of climate variables, such as temperature, pressure, and humidity, together with well-characterized and traceable estimates of the measurement uncertainty. To ensure that GRUAN data products are suitable to detect climate change, a scientifically robust instrument replacement strategy must always be adopted whenever there is a change in instrumentation. By fully characterizing any systematic differences between the old and new measurement system a temporally homogeneous data series can be created. One strategy is to operate both the old and new instruments in tandem for some overlap period to characterize any inter-instrument biases. However, this strategy can be prohibitively expensive at measurement sites operated by national weather services or research institutes. An alternative strategy that has been proposed is to alternate between the old and new instruments, so-called interlacing, and then statistically derive the systematic biases between the two instruments. Here we investigate the feasibility of such an approach specifically for radiosondes, i.e. flying the old and new instruments on alternating days. Synthetic data sets are used to explore the applicability of this statistical approach to radiosonde change management.

V. S. Kostsov, A. Kniffka, D. V. Ionov

<p>Tropospheric clouds are a very important component of the climate system and the hydrological cycle in the Arctic and sub-Arctic. Liquid water path (LWP) is one of the key parameters of clouds urgently needed for a variety of studies, including the snow cover and climate modelling at northern latitudes. A joint analysis was made of the LWP values obtained from observations by the SEVIRI satellite instrument and from ground-based observations by the RPG-HATPRO microwave radiometer near St Petersburg, Russia (60°&thinsp;N, 30°&thinsp;E). The time period of selected data sets spans 2 years (December 2012–November 2014) excluding winter months, since the specific requirements for SEVIRI observations restrict measurements at northern latitudes in winter when the solar zenith angle is too large. The radiometer measurement site is located very close to the shore of the Gulf of Finland, and our study has revealed considerable differences between the LWP values obtained by SEVIRI over land and over water areas in the region under investigation. Therefore, special attention was paid to the analysis of the LWP spatial distributions derived from SEVIRI observations at scales from 15 to 150&thinsp;km in the vicinity of St Petersburg. Good agreement between the daily median LWP values obtained from the SEVIRI and the RPG-HATPRO observations was shown: the rms difference was estimated at 0.016&thinsp;kg&thinsp;m⁻² for a warm season and 0.048&thinsp;kg&thinsp;m⁻² for a cold season. Over 7 months (February–May and August–October), the SEVIRI and the RPG-HATPRO instruments revealed similar diurnal variations in LWP, while considerable discrepancies between the diurnal variations obtained by the two instruments were detected in June and July. On the basis of reanalysis data, it was shown that the LWP diurnal cycles are characterised by considerable interannual variability.</p>

Pirjo Kristiina Virtanen, Sanna Saunaluoma

ABSTRACTProducing geometric designs and images on materials, such as pottery, basketry, and bead artwork, as well as the human body, is elemental and widespread among Amazonian Indigenous peoples. In this article, we examine the different geometric forms identified in the precolonial geoglyph architecture of southwestern Amazonia in the context of geometric design making and relational ontologies. Our aim is to explore earthwork iconography through the lens of Amerindian visual arts and movement. Combining ethnographic and archaeological data from the Upper Purus, Brazil, the article shows how ancient history and socio‐cosmology are deeply “written” onto the landscape in the form of geometric earthworks carved out of the soil, which materialize interactions between nonhuman and human actors. We underline skills in visualization, imaginative practices, and movement as ways to promote well‐balanced engagements with animated life forms. Here, iconography inserted in the landscape is both a form of writing and also emerges as an agent, affecting people through visual and corporal practices. [geometric designs,earthworks,visualization,movement,Amazonia]

M. D. Dilmi, C. Mallet, L. Barthes et al.

Rain time series records are generally studied using rainfall rate or accumulation parameters, which are estimated for a fixed duration (typically 1 min, 1 h or 1 day). In this study we use the concept of <q>rain events</q>. The aim of the first part of this paper is to establish a parsimonious characterization of rain events, using a minimal set of variables selected among those normally used for the characterization of these events. A methodology is proposed, based on the combined use of a genetic algorithm (GA) and self-organizing maps (SOMs). It can be advantageous to use an SOM, since it allows a high-dimensional data space to be mapped onto a two-dimensional space while preserving, in an unsupervised manner, most of the information contained in the initial space topology. The 2-D maps obtained in this way allow the relationships between variables to be determined and redundant variables to be removed, thus leading to a minimal subset of variables. We verify that such 2-D maps make it possible to determine the characteristics of all events, on the basis of only five features (the event duration, the peak rain rate, the rain event depth, the standard deviation of the rain rate event and the absolute rain rate variation of the order of 0.5). From this minimal subset of variables, hierarchical cluster analyses were carried out. We show that clustering into two classes allows the conventional convective and stratiform classes to be determined, whereas classification into five classes allows this convective–stratiform classification to be further refined. Finally, our study made it possible to reveal the presence of some specific relationships between these five classes and the microphysics of their associated rain events.

W. Su, J. Corbett, Z. Eitzen et al.

Radiative fluxes at the top of the atmosphere (TOA) from the Clouds and the Earth's Radiant Energy System (CERES) instrument are fundamental variables for understanding the Earth's energy balance and how it changes with time. TOA radiative fluxes are derived from the CERES radiance measurements using empirical angular distribution models (ADMs). This paper evaluates the accuracy of CERES TOA fluxes using direct integration and flux consistency tests. Direct integration tests show that the overall bias in regional monthly mean TOA shortwave (SW) flux is less than 0.2 Wm⁻² and the RMSE is less than 1.1 Wm⁻². The bias and RMSE are very similar between Terra and Aqua. The bias in regional monthly mean TOA LW fluxes is less than 0.5 Wm⁻² and the RMSE is less than 0.8 Wm⁻² for both Terra and Aqua. The accuracy of the TOA instantaneous flux is assessed by performing tests using fluxes inverted from nadir- and oblique-viewing angles using CERES along-track observations and temporally and spatially matched MODIS observations, and using fluxes inverted from multi-angle MISR observations. The averaged TOA instantaneous SW flux uncertainties from these two tests are about 2.3 % (1.9 Wm⁻²) over clear ocean, 1.6 % (4.5 Wm⁻²) over clear land, and 2.0 % (6.0 Wm⁻²) over clear snow/ice; and are about 3.3 % (9.0 Wm⁻²), 2.7 % (8.4 Wm⁻²), and 3.7 % (9.9 Wm⁻²) over ocean, land, and snow/ice under all-sky conditions. The TOA SW flux uncertainties are generally larger for thin broken clouds than for moderate and thick overcast clouds. The TOA instantaneous daytime LW flux uncertainties derived from the CERES-MODIS test are 0.5 % (1.5 Wm⁻²), 0.8 % (2.4 Wm⁻²), and 0.7 % (1.3 Wm⁻²) over clear ocean, land, and snow/ice; and are about 1.5 % (3.5 Wm⁻²), 1.0 % (2.9 Wm⁻²), and 1.1 % (2.1 Wm⁻²) over ocean, land, and snow/ice under all-sky conditions. The TOA instantaneous nighttime LW flux uncertainties are about 0.5–1 % (< 2.0 Wm⁻²) for all surface types. Flux uncertainties caused by errors in scene identification are also assessed by using the collocated CALIPSO, CloudSat, CERES and MODIS data product. Errors in scene identification tend to underestimate TOA SW flux by about 0.6 Wm⁻² and overestimate TOA daytime (nighttime) LW flux by 0.4 (0.2) Wm⁻² when all CERES viewing angles are considered.

L. Klüser, N. Killius, G. Gesell

The cloud processing scheme APOLLO (AVHRR Processing scheme Over cLouds, Land and Ocean) has been in use for cloud detection and cloud property retrieval since the late 1980s. The physics of the APOLLO scheme still build the backbone of a range of cloud detection algorithms for AVHRR (Advanced Very High Resolution Radiometer) heritage instruments. The APOLLO_NG (APOLLO_NextGeneration) cloud processing scheme is a probabilistic interpretation of the original APOLLO method. It builds upon the physical principles that have served well in the original APOLLO scheme. Nevertheless, a couple of additional variables have been introduced in APOLLO_NG. Cloud detection is no longer performed as a binary yes/no decision based on these physical principles. It is rather expressed as cloud probability for each satellite pixel. Consequently, the outcome of the algorithm can be tuned from being sure to reliably identify clear pixels to conditions of reliably identifying definitely cloudy pixels, depending on the purpose. The probabilistic approach allows retrieving not only the cloud properties (optical depth, effective radius, cloud top temperature and cloud water path) but also their uncertainties. APOLLO_NG is designed as a standalone cloud retrieval method robust enough for operational near-realtime use and for application to large amounts of historical satellite data. The radiative transfer solution is approximated by the same two-stream approach which also had been used for the original APOLLO. This allows the algorithm to be applied to a wide range of sensors without the necessity of sensor-specific tuning. Moreover it allows for online calculation of the radiative transfer (i.e., within the retrieval algorithm) giving rise to a detailed probabilistic treatment of cloud variables. This study presents the algorithm for cloud detection and cloud property retrieval together with the physical principles from the APOLLO legacy it is based on. Furthermore a couple of example results from NOAA-18 are presented.

I. Ježek, L. Drinovec, L. Ferrero et al.

We have used two methods for measuring emission factors (EFs) in real driving conditions on five cars in a controlled environment: the stationary method, where the investigated vehicle drives by the stationary measurement platform and the composition of the plume is measured, and the chasing method, where a mobile measurement platform drives behind the investigated vehicle. We measured EFs of black carbon and particle number concentration. The stationary method was tested for repeatability at different speeds and on a slope. The chasing method was tested on a test track and compared to the portable emission measurement system. We further developed the data processing algorithm for both methods, trying to improve consistency, determine the plume duration, limit the background influence and facilitate automatic processing of measurements. The comparison of emission factors determined by the two methods showed good agreement. EFs of a single car measured with either method have a specific distribution with a characteristic value and a long tail of super emissions. Measuring EFs at different speeds or slopes did not significantly influence the EFs of different cars; hence, we propose a new description of vehicle emissions that is not related to kinematic or engine parameters, and we rather describe the vehicle EF with a characteristic value and a super emission tail.

R. Schnitzhofer, A. Metzger, M. Breitenlechner et al.

The CLOUD experiment (<b>C</b>osmics <b>L</b>eaving <b>OU</b>tdoor <b>D</b>roplets) investigates the nucleation of new particles and how this process is influenced by galactic cosmic rays in an electropolished, stainless-steel environmental chamber at CERN (European Organization for Nuclear Research). Since volatile organic compounds (VOCs) can act as precursor gases for nucleation and growth of particles, great efforts have been made to keep their unwanted background levels as low as possible and to quantify them. In order to be able to measure a great set of VOCs simultaneously in the low parts per trillion (pptv) range, proton-transfer-reaction mass spectrometry (PTR-MS) was used. Initially the total VOC background concentration strongly correlated with ozone in the chamber and ranged from 0.1 to 7 parts per billion (ppbv). Plastic used as sealing material in the ozone generator was found to be a major VOC source. Especially oxygen-containing VOCs were generated together with ozone. These parts were replaced by stainless steel after CLOUD3, which strongly reduced the total VOC background. An additional ozone-induced VOC source is surface-assisted reactions at the electropolished stainless steel walls. The change in relative humidity (RH) from very dry to humid conditions increases background VOCs released from the chamber walls. This effect is especially pronounced when the RH is increased for the first time in a campaign. Also the dead volume of inlet tubes for trace gases that were not continuously flushed was found to be a short but strong VOC contamination source. For lower ozone levels (below 100 ppbv) the total VOC contamination was usually below 1 ppbv and therewith considerably cleaner than a comparable Teflon chamber. On average about 75% of the total VOCs come from only five exact masses (tentatively assigned as formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid), which have a rather high vapour pressure and are therefore not important for nucleation and growth of particles.

R. Wilson, H. Luce, H. Hashiguchi et al.

The present paper addresses the detection of turbulence based on the Thorpe (1977) method applied to an atmosphere where saturation of water vapor occurs. The detection method proposed by Thorpe relies on the sorting in ascending order of a measured profile of a variable conserved through adiabatic processes, (e.g. potential temperature). For saturated air, the reordering should be applied to a moist-conservative potential temperature, &theta;_m, which is analogous to potential temperature for a dry (subsaturated) atmosphere. Here, &theta;_m is estimated from the Brunt–V&auml;is&auml;l&auml; frequency derived by Lalas and Einaudi (1974) in a saturated atmosphere. The application to balloon data shows that the effective turbulent fraction of the troposphere can dramatically increase when saturation is taken into account. Preliminary results of comparisons with data simultaneously collected from the VHF Middle and Upper atmosphere radar (MUR, Japan) seem to give credence to the proposed approach.

Abdul-Hamid Soubra, Nut Mao