Cloud Patterns Research Articles

전통문양을 활용한 현대적 원피스 디자인 개발 연구 - 문양의 배치 및 색채 배색 과정을 중심으로 -

The purpose of this study is to link traditional patterns to modern clothing. Of all the traditional patterns, the cloud pattern was chosen for use during the development of a modern one-piece dress design. This study is based upon document searches, including research papers. Through these searches, it investigates the symbolic meaning, historical change, and formation of the cloud pattern. Based on this investigation, the study attempts to modernize the cloud pattern and apply the modernized patterns to the design of a one-piece dress. The design procedure includes three sub-processes: selection, arrangement, and color-scheme. The selection process was divided in two: first, the original form of the cloud pattern was hand-drawn using tracing paper: second, the form of the pattern was edited using Adobe Photoshop. The arrangement of the pattern was made through the checklist conception method, containing the following functions: expand, reset, repeat, and overlap. For the color-scheme of the pattern, Roy Lichtenstein's(1923~1997) work was selected, and the colors in his work were adopted when dyeing the rest of the one-piece dress as well as the cloud features. In conclusion, six modern designs of the one-piece dress were created by using one of Korea's traditional patterns - the cloud pattern. Therefore, this study can offer invaluable suggestions for multifaceted research on how to come up with design concepts which apply Korea's traditional patterns to clothing design.

전통 운문(雲紋)을 모티브로 한 셔츠디자인 연구

This work is to develop a T-shirt by adopting a unique cloud pattern (a good auspicious sign as design material) from traditional native Korean patterns for application to various cultural products and textile design cloth patterns; subsequently, a T-shirt design was processed based on this. As a research method, computer design programs Adobe Illustrator CS3 and Adobe Photoshop CS3 were used along with a literature examination as part of motive for design development and pattern realization. Three basic motives were selected as a new formative image in this work, utilizing graphical elements such as abridgement and simplicity of pattern, where flower-shaped cloud pattern, uprising cloud pattern, and 卍-shaped or swastika-shaped pattern of traditional cloud patterns were selected. Each motive diverged into two motives via the shape transformation and the application of different colors. The newly developed basic motive was further processed into a combination of one-time repeat pattern, stripe pattern, and application pattern with mixed cloud motives (that were previously developed), which altogether turned out to be 36 pieces of textile design. In addition, with newly developed motive designs and textile designs, a total of 12 shirt designs for 4 pieces were developed for these three each. The shirt design was developed into a shirt blouse, sleeveless T-shirt, half-sleeve T-shirt, and sports T-shirt among others in order to fit various uses and purposes.

Cloud pattern and water relations in Picea rubens and Abies fraseri, southern Appalachian Mountains, USA

The spruce-fir [Picea rubens Sarg.-Abies fraseri (Pursh) Poir.] forests of the southern Appalachian Mountains are considered refugial, endangered communities that exist on only seven mountaintop areas in Virginia and North Carolina, USA. These relict forests continue to be threatened by stress factors such as logging, acid rain deposition, attacks from invasive insects, and climate change. It has been suggested that these communities have persisted because of frequent cloudiness and periods of cloud immersion (fog), although few studies have examined corresponding effects on microclimate and tree ecophysiology. Incident sunlight (PPFD), air temperature, vapor pressure deficit (VPD), and xylem water potentials were measured throughout the summer growing season in Mount Mitchell State Park, NC (35°45′53″N, 82°15′54″W), along with continuous camera recordings of the forest canopy and accompanying cloud conditions. Approximately 60% of all summer days had at least 2h of cloud immersion with the large majority (80.3%) of immersion events occurring during morning hours. Cloud-immersed days had the greatest reduction in cumulative daily PPFD compared to clear days (11.09molm−2day−1 vs. 38.03molm−2day−1, respectively), as well as substantially reduced mean VPD (0.98kPa vs. 1.81kPa) but only slightly lower mean air temperatures (14.5°C vs. 14.9°C, respectively). Moreover, xylem water potential (Ψ) increased significantly (∼0.2MPa; values) from morning to afternoon on cloud-immersed days. In contrast, clear days showed no afternoon recovery in Ψ, but a continued decrease during the afternoon. Juvenile Ψ was more responsive to daily cloud regime compared to adult Ψ and had a strong negative correlation with vapor pressure deficit. When all measurement days were sorted by the cloud pattern of the previous day, there was a strong response in juveniles trees, i.e. Ψ increased following previous afternoon cloud-immersion. Juveniles of both species also had greater seasonal decreases in Ψ than adults (P. rubens, adult: 0.05MPa, juvenile: 0.13MPa; A. fraseri, adult: 0.06MPa, juvenile: 0.20Mpa). For climate change models that predict a higher cloud base (resulting in less immersion) and dryer conditions, the water relations of Abies fraseri and Picea rubens could be substantially and negatively influenced.

Numerical simulation for a wind dust event in the US/Mexico border region

Soil-derived dust represents one of the major components of the natural atmospheric aerosols. Arid and semiarid areas with unpaved and non-vegetated land cover are particularly vulnerable to windblown dust, which results in high particulate matter pollution. To understand, predict, and mitigate the impact of dust aerosol on air quality and climate, it is necessary to parameterize the emission rate of dust particles from the wind erosion processes accurately. However, windblown dust emission is poorly represented in existing air quality models. In this paper, a windblown dust emission model has been developed based on a parameterization of threshold wind friction velocity depending on the roughness of surface, vegetation type, soil type, soil moisture content, and on the size distribution of aerosols. The proposed dust model incorporates into a region air quality modeling system to simulate a North American dust storm episode occurring near the border of southwestern USA and northwestern region of Mexico on 23 February 2007. It is shown that the implementation of a windblown dust model in an air quality model can significantly improve the model capability for capturing the dust episode. The simulation of the model is in good agreement with the evolution of dust distribution. The modeled dust spatial patterns matched dust cloud patterns appearing on satellite images. Implementation of the windblown dust model successfully captured the time of peak particulate matter (PM) concentrations for both PM10 and PM2.5, as well as the peak value of the PM2.5 concentration. The modeled results clearly demonstrate an improved ability to predict PM events by applying the windblown dust emission scheme.

Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

Abstract. On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137Cs, the inversion results give a total emission of 36.6 (20.1–53.1) PBq, or about 43% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14–15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude at the time when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions may not have originated only from the damaged reactor cores, but also from the spent-fuel pool of unit 4. This would also confirm that the spraying was an effective countermeasure. We explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. Radioactive clouds reached North America on 15 March and Europe on 22 March. By middle of April, 133Xe was fairly uniformly distributed in the middle latitudes of the entire Northern Hemisphere and was for the first time also measured in the Southern Hemisphere (Darwin station, Australia). In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement. Altogether, we estimate that 6.4 PBq of 137Cs, or 18% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 PBq, or 1.9% of the total fallout were deposited on land areas other than Japan.

Pattern-driven green adaptation of process-based applications and their runtime infrastructure

Business processes are a key aspect of modern organization. In recent years, business process management and optimization has been applied to different cross-cutting concerns such as security, compliance, or Green IT, for example. Based on the ecological characteristics of a business process, proper environmentally sustainable adaptation strategies can be chosen to improve the total environmental impact of the business process. We use ecological sustainable adaptation strategies that are described as green business process patterns. The application of such a green business process pattern, however, affects the business process layer, the application component and the infrastructure layer. This implies that changes in the application infrastructure also need to be considered. Hence, we use best practices of cloud application architectures which are described as Cloud patterns. To guide developers through the adaptation process we propose a pattern-based approach in this work. We correlate Cloud patterns relevant for sustainable business processes to green business process patterns and organize them within a classification. To provide concrete implementation support we further annotate these Cloud patterns to application component models that are described with the topology and orchestration specification for cloud applications (TOSCA). Using these annotations, we describe a method that provides the means to optimize business processes based on green business process patterns through adapting the implementation of application components with concrete TOSCA implementation models.

An Objective Infrared Imagery Analysis for Typhoon Jangmi

A typhoon usually develops from an unstructured cloud cluster. In general, the more axis-symmetry a typhoon cloud pattern is, the stronger the typhoon intensity could be. This study analyzes the MTSAT_IR1 image data of severe typhoon Jangmi during the period from tropical depression to severe typhoon stage. The gradient of the gray values in the MTSAT_IR1 image is calculated from the horizontal and vertical derivatives by using Sobel's template. Then, the deviation angle of each gradient vector relative to a radial line extending from typhoon eye is calculated. The results show that the deviation angle distribution become approaching Gaussian distribution when the intensity of typhoon increase from tropical depression to severe typhoon period, and the structures of cloud cluster will become more axis-symmetry to the center of typhoon.

The Low-Level Atmospheric Circulation near Tongoy Bay–Point Lengua de Vaca (Chilean Coast, 30°S)

Abstract Strong southerly, terrain parallel winds often occur along the coast of north-central Chile (25°–35°S) embedded in the marine atmospheric boundary layer and the lower part of the capping temperature inversion. Their offshore structure and variability have received considerable attention because of the effect on open-ocean processes and connection with the southeast Pacific cloud layer. Mesoscale low-level circulations linked to the coastal topography (e.g., coastal jets and sea breeze) are less studied in Chile, but are particularly relevant as they alter the upper-ocean circulation and the cloud pattern in the nearshore strip. Surface, radiosonde, and airborne meteorological observations near point Lengua de Vaca (LdV)–Tongoy Bay (TB) at 30°S are used alongside numerical modeling to understand the local circulation near a prominent upwelling center. Most observations were gathered during the Variability of the American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study Chilean Upwelling Experiment (VOCALS-CUpEx) during two weeks in late spring 2009. The regional topography resembles other major capes, but south of TB and east of LdV there is a low (100–300 m), dry marine terrace bounded by high elevation at the coast (~600 m) and farther inland. Coastal soundings 25 km upstream of LdV revealed a southerly wind maximum near the surface and another at 900 m separated by a destabilized layer, deviating from the two-layer model often applied to coastal flow. In the morning a shallow sea breeze penetrates from TB to the marine terrace, but is overridden by southerly flow in the afternoon. Furthermore, between 400 and 900 m, warm continental air is advected from over the marine terrace creating a residual boundary layer over TB. Concurrent with slower changes offshore, the low-level warming over TB leads to a marked cross-shore pressure gradient enhancing the coastal jet just north of LdV.

Power spectral analysis of Jupiter’s clouds and kinetic energy from Cassini

We present suggestive evidence for an inverse energy cascade within Jupiter’s atmosphere through a calculation of the power spectrum of its kinetic energy and its cloud patterns. Using Cassini observations, we composed full-longitudinal mosaics of Jupiter’s atmosphere at several wavelengths. We also utilized image pairs derived from these observations to generate full-longitudinal maps of wind vectors and atmospheric kinetic energy within Jupiter’s troposphere. We computed power spectra of the image mosaics and kinetic energy maps using spherical harmonic analysis. Power spectra of Jupiter’s cloud patterns imaged at certain wavelengths resemble theoretical spectra of two-dimensional turbulence, with power-law slopes near −5/3 and −3 at low and high wavenumbers, respectively. The slopes of the kinetic energy power spectrum are also near −5/3 at low wavenumbers. At high wavenumbers, however, the spectral slopes are relatively flatter than the theoretical prediction of −3. In addition, the image mosaic and kinetic energy power spectra differ with respect to the location of the transition in slopes. The transition in slope is near planetary wavenumber 70 for the kinetic energy spectra, but is typically above 200 for the image mosaic spectra. Our results also show the importance of calculating spectral slopes from full 2D velocity maps rather than 1D zonal mean velocity profiles, since at large wavenumbers the spectra differ significantly, though at low wavenumbers, the 1D zonal and full 2D kinetic energy spectra are practically indistinguishable. Furthermore, the difference between the image and kinetic energy spectra suggests some caution in the interpretation of power spectrum results solely from image mosaics and its significance for the underlying dynamics. Finally, we also report prominent variations in kinetic energy within the equatorial jet stream that appear to be associated with the 5μm hotspots. Other eddies are present within the flow collar of the Great Red Spot, suggesting caution when interpreting snapshots of the flow inside these features as representative of a time-averaged state.

Assimilating remotely sensed cloud optical thickness into a mesoscale model

Abstract. The Advanced Regional Prediction System, a mesoscale atmospheric model, is applied to simulate the month of June 2006 with a focus on the near surface air temperatures around Paris. To improve the simulated temperatures which show errors up to 10 K during a day on which a cold front passed Paris, a data assimilation procedure to calculate 3-D analysis fields of specific cloud liquid and ice water content is presented. The method is based on the assimilation of observed cloud optical thickness fields into the Advanced Regional Prediction System model and operates on 1-D vertical columns, assuming that the horizontal background error covariance is infinite, i.e. an independent pixel approximation. The rationale behind it is to find vertical profiles of cloud liquid and ice water content that yield the observed cloud optical thickness values and are consistent with the simulated profile. Afterwards, a latent heat adjustment is applied to the temperature in the vertical column. Data from several meteorological stations in the study area are used to verify the model simulations. The results show that the presented assimilation procedure is able to improve the simulated 2 m air temperatures and incoming shortwave radiation significantly during cloudy days. The scheme is able to alter the position of the cloud fields significantly and brings the simulated cloud pattern closer to the observations. As the scheme is rather simple and computationally inexpensive, it is a promising new technique to improve the surface fields of retrospective model simulations for variables that are affected by the position of the clouds.

Morphology of the cloud tops as observed by the Venus Express Monitoring Camera

Since the discovery of ultraviolet markings on Venus, their observations have been a powerful tool to study the morphology, motions and dynamical state at the cloud top level. Here we present the results of investigation of the cloud top morphology performed by the Venus Monitoring Camera (VMC) during more than 3 years of the Venus Express mission. The camera acquires images in four narrow-band filters centered at 365, 513, 965 and 1010 nm with spatial resolution from 50 km at apocentre to a few hundred of meters at pericentre. The VMC experiment provides a significant improvement in the Venus imaging as compared to the capabilities of the earlier missions. The camera discovered new cloud features like bright “lace clouds” and cloud columns at the low latitudes, dark polar oval and narrow circular and spiral “grooves” in the polar regions, different types of waves at the high latitudes. The VMC observations revealed detailed structure of the sub-solar region and the afternoon convective wake, the bow-shape features and convective cells, the mid-latitude transition region and the “polar cap”. The polar orbit of the satellite enables for the first time nadir viewing of the Southern polar regions and an opportunity to zoom in on the planet. The experiment returned numerous images of the Venus limb and documented global and local brightening events. VMC provided almost continuous monitoring of the planet with high temporal resolution that allowed one to follow changes in the cloud morphology at various scales. We present the in-flight performance of the instrument and focus in particular on the data from the ultraviolet channel, centered at the characteristic wavelength of the unknown UV absorber that yields the highest contrasts on the cloud top. Low latitudes are dominated by relatively dark clouds that have mottled and fragmented appearance clearly indicating convective activity in the sub-solar region. At ∼50° latitude this pattern gives way to streaky clouds suggesting that horizontal, almost laminar, flow prevails here. Poleward from about 60°S the planet is covered by almost featureless bright polar hood sometimes crossed by dark narrow (∼300 km) spiral or circular structures. This global cloud pattern can change on time scales of a few days resulting in global and local “brightening events” when the bright haze can extend far into low latitudes and/or increase its brightness by 30%. Close-up snapshots reveal plenty of morphological details like convective cells, cloud streaks, cumulus-like columns, wave trains. Different kinds of small scale waves are frequently observed at the cloud top. The wave activity is mainly observed in the 65–80° latitude band and is in particular concentrated in the region of Ishtar Terra that suggests their possible orographic origin. The VMC observations have important implications for the problems of the unknown UV absorber, microphysical processes, dynamics and radiative energy balance at the cloud tops. They are only briefly discussed in the paper, but each of them will be the subject of a dedicated study.

Exploring Policy-Formulation for SMEs in Cloud Computing: The Case of Turkey

The promise of competitiveness that clouds offer to enterprises creates a substantial part of the cloud phenomenon. 2010 European Union report on cloud computing identifies the strong commercial nature of clouds and addresses new policies and actions for the competitiveness of European industry. Today, European Union attributes competitiveness to the smart growth of SMEs. The concept of smart growth is based on effective policies that foster innovation and capability to adopt the dynamics of information society. This paper aims at exploring the policymaking methods for cloud computing that will serve to enhance the competitiveness of SMEs. It analyses the dynamics of Turkish policy-making and discusses the role of EU policies in a candidate country as the motivators of migration to clouds. It is an output of an ongoing research on cloud computing in Turkey. This paper contributes to the literature as being one of the first studies on policy-making for cloud computing. It provides a twofold policy tool proposed for policy-makers. First, it identifies the dynamics of policy-making by adapting the model of Van Schendelen’s general categories of decision buttons for EU lobbying to the Turkish policy-making mechanisms. Secondly, it detects the main patterns of cloud computing policy under five priority areas as a check list for policy-makers.

Automated cloud tracking system for the Akatsuki Venus Climate Orbiter data

Japanese Venus Climate Orbiter, Akatsuki, is cruising to approach to Venus again although its first Venus orbital insertion (VOI) has been failed. At present, we focus on the next opportunity of VOI and the following scientific observations.We have constructed an automated cloud tracking system for processing data obtained by Akatsuki in the present study. In this system, correction of the pointing of the satellite is essentially important for improving accuracy of the cloud motion vectors derived using the cloud tracking. Attitude errors of the satellite are reduced by fitting an ellipse to limb of an imaged Venus disk. Next, longitude–latitude distributions of brightness (cloud patterns) are calculated to make it easy to derive the cloud motion vectors. The grid points are distributed at regular intervals in the longitude–latitude coordinate. After applying the solar zenith correction and a highpass filter to the derived longitude–latitude distributions of brightness, the cloud features are tracked using pairs of images. As a result, we obtain cloud motion vectors on longitude–latitude grid points equally spaced. These entire processes are pipelined and automated, and are applied to all data obtained by combinations of cameras and filters onboard Akatsuki. It is shown by several tests that the cloud motion vectors are determined with a sufficient accuracy. We expect that longitude–latitude data sets created by the automated cloud tracking system will contribute to the Venus meteorology.

Coherent Light Scattering from a Two-Dimensional Mott Insulator

We experimentally demonstrate coherent light scattering from an atomic Mott insulator in a two-dimensional lattice. The far-field diffraction pattern of small clouds of a few hundred atoms was imaged while simultaneously laser cooling the atoms with the probe beams. We describe the position of the diffraction peaks and the scaling of the peak parameters by a simple analytic model. In contrast to Bragg scattering, scattering from a single plane yields diffraction peaks for any incidence angle. We demonstrate the feasibility of detecting spin correlations via light scattering by artificially creating a one-dimensional antiferromagnetic order as a density wave and observing the appearance of additional diffraction peaks.

Estimation of the Upper-Layer Rotation and Maximum Wind Speed of Tropical Cyclones via Satellite Imagery

Abstract The movement of convective rainbands embedded in a tropical cyclone (TC) is usually derived from satellite images via the atmospheric motion vector (AMV) method or through the calculation of a radar’s echo track. In estimating the rotation speed of a TC rainband, however, the land-based radar can only detect approaching tropical cyclones within the vicinity. The AMV method is unable to fully account for the TC eyewall movement, thus making it difficult to estimate the TC intensity. The widely used method in estimating the TC maximum wind speed is the Dvorak technique in which the cloud pattern is extracted from only one image. In this study, the rainband rotation speeds are computed via satellite imagery and further applied in estimating the TC maximum wind speed. In contrast to previous research, this study adopts an innovative method by using two subsequent geostationary satellite images. The TC spin rates observed by weather satellites could often be seen to be positively related to the TC intensity. Analyses of the relationship between the typhoon wind intensity and estimated rotation speed at the 130–260-km ring via infrared channels are conducted for major typhoon cases that occurred during 2000–05 in the northwestern Pacific Ocean. Results show that the correlation between the wind intensity and estimated rotation speeds is strong for most of the cases. The highest R2 value from the individual cases could reach 0.93, and on an annual basis it could attain a value of 0.67. The mean R2 value for the 2000–05 dataset was roughly 0.53. The correlation between the wind intensity and estimated rotation speeds is further improved by factoring in the previous 6-h average rotation speeds. A regression equation is derived from the chosen typhoon cases between 2000 and 2005, which is utilized in verifying the major typhoon occurrences during 2006–08. The mean absolute error (MAE) of the hourly and 6-h average intensity estimates during 2000–08 was 20 and 18.7 kt, respectively (1 kt ≃ 0.5 m s−1). The best verification result occurred during 2008, for which the R2 value and MAE could reach 0.7 and 15.6, respectively. These research results demonstrate the suitability of using geostationary satellite image data in estimating the maximum wind speed. Nevertheless, the drawback of this study is that sometimes the rotation speeds will become slower when tropical cyclones mature because of the strong outflow of the secondary circulation. It is assumed that the relationship between the estimated rotation speeds and wind intensity can be further improved if the outflow speed of the tropical cyclones is also considered.

Jupiter's zonal winds: are they bands of homogenized potential vorticity organized as a monotonic staircase?

The east-west striped pattern of clouds in Jupiter's weather layer is accompanied by a zonal flow containing 12 eastward-going jet streams alternating in latitude with westward-going jet streams. Based on theory, simulation and observations of the Earth's oceans and atmosphere, it is conjectured that Jupiter's weather layer is made of bands of constant potential vorticity (PV), where the interfaces between bands are at the latitudes of the maxima of the eastward-going jet streams. It is speculated that the mixing of PV on Jupiter is analogous to the mixing of salt in the ocean by the Phillips effect, which causes the salt density to form a monotonic 'staircase'. It is hypothesized that the PV in Jupiter's weather layer is also a staircase, decreasing from north to south. PV is a function of vorticity, as well as parameters with unknown values, e.g. the vertical stratification and the zonal flow beneath the observable weather layer. Therefore, these hypotheses cannot be tested directly. Using an atmospheric model that contains these unknown parameters, we solved the inverse problem and found values of the unknown parameters (and their uncertainties) that best fit Jovian observations. The unknown parameters influence how the zonal flow interacts with large vortices, e.g. the Great Red Spot (GRS; the largest and longest-lived Jovian vortex, centred at 23° S) and the Oval BA (the second largest vortex, centred at 33° S). Although we found that the PV distribution is approximately piecewise-constant and that the peaks of the eastward-going jet streams are at the latitudes of PV interfaces, there is also a PV interface at 20° S, where there is a westward-going jet stream. We find that the zonal PV is not a monotonic staircase due to the 'backwards' interface at 20° S. We show that this backwards interface is necessary to make the GRS nearly round, and that without that interface, the Red Spot would be highly elongated in the east-west direction and probably unstable.

Low clouds and fog along the South-Western African coast — Satellite-based retrieval and spatial patterns

The spatial and temporal patterns of fog and low clouds along the South-Western African coast are characterized based on an evaluation of Meteosat SEVIRI satellite data. A technique for the detection of fog/low clouds in the region is introduced, and validated using 1year of CALIOP cloud lidar products, showing reliable performance. The frequency of fog and low cloud in the study area is analyzed by systematic application of the technique to all available Meteosat SEVIRI scenes from 2004 to 2009, for 7:00 UTC and 14:00 UTC. The highest frequencies are encountered in the area around Walvis Bay, with a peak in the summer months. Fog and low clouds clear by 14:00 UTC almost everywhere over land. Supplementary data are available at doi:10.1594/PANGAEA.755427.

Sea surface imprints of coastal mountain lee waves imaged by synthetic aperture radar

[1] A group of mountain lee waves is observed on an Envisat advanced synthetic aperture radar (SAR) image on the lee side of Mountain Laoshan (1133 m) along the Yellow Sea coast of China. The lee waves are shown as alternating bright and dark patterns on the SAR image, indicating the ocean surface wind oscillation associated with the atmospheric wavefield. The horizontal wind variation between wave crest and trough is from 7 to 17 m/s. A Moderate Resolution Imaging Spectroradiometer image acquired about 8.5 h prior to the SAR pass also showed the same group of standing lee waves. The cloud pattern matches the high-wind pattern in the SAR-derived wind image. The mesoscale Weather Research and Forecasting (WRF) model is used to simulate the lee wave phenomenon. We run the triply nested grid model with the highest horizontal resolution of 1 km. The WRF model successfully captures the characteristics of the lee wave. The waves are generated by the terrain forcing and the wave-induced perturbation propagates very strongly upward to the 500 hPa level. The event lasts about 24 h. Based on the WRF model wind results, we run a radar imaging model to simulate the SAR observation. The normalized radar cross section (NRCS) variations induced by the lee wave are compared between the radar simulation and the actual SAR observation. Reasonable agreement is reached.

A high-quality monthly total cloud amount dataset for Australia

A high-quality monthly total cloud amount dataset for 165 stations has been developed for monitoring and assessing long-term trends in cloud cover over Australia. The dataset is based on visual 9 a.m. and 3 p.m. observations of total cloud amount, with most records starting around 1957. The quality control process involved examination of historical station metadata, together with an objective statistical test comparing candidate and reference cloud series. Individual cloud series were also compared against rainfall and diurnal temperature range series from the same site, and individual cloud series from neighboring sites. Adjustments for inhomogeneities caused by relocations and changes in observers were applied, as well as adjustments for biases caused by the shift to daylight saving time in the summer months. Analysis of these data reveals that the Australian mean annual total cloud amount is characterised by high year-to-year variability and shows a weak, statistically non-significant increase over the 1957–2007 period. A more pronounced, but also non-significant, decrease from 1977 to 2007 is evident. A strong positive correlation is found between all-Australian averages of cloud amount and rainfall, while a strong negative correlation is found between mean cloud amount and diurnal temperature range. Patterns of annual and seasonal trends in cloud amount are in general agreement with rainfall changes across Australia, however the high-quality cloud network is too coarse to fully capture topographic influences. Nevertheless, the broadscale consistency between patterns of cloud and rainfall variations indicates that the new total cloud amount dataset is able to adequately describe the broadscale patterns of change over Australia. Favourable simple comparisons between surface and satellite measures of cloudiness suggest that satellites may ultimately provide the means for monitoring long-term changes in cloud over Australia. However, due to the relative shortness and homogeneity problems of the satellite record, a robust network of surface cloud observations will be required for many years to come.

Nocturnal convective cloud formation under clear‐sky conditions at the eastern Andes of south Ecuador

The formation of nocturnal convective clouds at the eastern Andes of south Ecuador and the adjacent Peruvian Amazon basin was investigated in a numerical model study. Their formation is expected to be an interactive procedure of nocturnal downslope flows in the Andean terrain, which forms a concave drainage system in the target area. Satellite imagery were used for both the identification of a sample case with a nocturnal cold cloud appearance and for the verification of the simulated results. The cloud patterns were distinguished on the basis of IR temperatures. A comparison of the data demonstrated the occurrence of a cold cloud shield in the target area, although the modeled cluster is significantly smaller. Further analysis of the development of the convective cells confirmed the assumed underlying processes. A strong current in the lower atmosphere, presumably a drainage flow, was recognizable in association with strong moisture convergence using a cross section through the cluster. Their presence was confirmed on the basis of their characteristic features and the surface energy fluxes as the driving force for thermally induced downslope flows.