The recently increasing development of whole sky imagers enables temporal and spatial high-resolution sky observations. One application already performed in most cases is the estimation of fractional ...sky cover. A distinction between different cloud types, however, is still in progress. Here, an automatic cloud classification algorithm is presented, based on a set of mainly statistical features describing the color as well as the texture of an image. The k-nearest-neighbour classifier is used due to its high performance in solving complex issues, simplicity of implementation and low computational complexity. Seven different sky conditions are distinguished: high thin clouds (cirrus and cirrostratus), high patched cumuliform clouds (cirrocumulus and altocumulus), stratocumulus clouds, low cumuliform clouds, thick clouds (cumulonimbus and nimbostratus), stratiform clouds and clear sky. Based on the Leave-One-Out Cross-Validation the algorithm achieves an accuracy of about 97%. In addition, a test run of random images is presented, still outperforming previous algorithms by yielding a success rate of about 75%, or up to 88% if only "serious" errors with respect to radiation impact are considered. Reasons for the decrement in accuracy are discussed, and ideas to further improve the classification results, especially in problematic cases, are investigated.
Satellite remote sensing products such as Meteosat Second Generation (MSG) Infra Red (IR) dust index and Ozone Monitoring Instrument (OMI) Aerosol Index (AI) are commonly used to infer dust source ...areas. Here, two methods for dust source identification are compared, (1) a “back-tracking” method applied to 15-minute MSG IR dust index, and (2) a “frequency” method applied to daily OMI AI and daily MODIS DeepBlue Aerosol Optical Thickness (AOT) data.
Using the “back-tracking” method, dust source areas are inferred by tracking individual dust plumes back to their place of origin, allowed by the high temporal resolution of the MSG images. OMI AI and MODIS Deep Blue AOT products are available on daily resolution only, which does not allow for back-tracking of individual dust plumes. Thus, dust source areas are identified by relating the frequencies of occurrence of high dust loadings to source areas.
The spatial distribution of inferred dust source areas not only from the two methods, but also from the two satellite products, shows significant differences. The MSG back-tracking method highlights frequent dust emission from sources within complex terrain, while frequencies of high OMI AI values emphasise topographic basins as important dust source areas. Dust source areas retrieved from DeepBlue AOTs are generally further south towards the Sahel region. This study shows that the temporal resolution of satellite dust products is a key issue in identifying dust source areas. Both, the spatial distribution of dust sources and their annual cycle strongly depend on the acquisition time related to the start of dust emission.
► Comparison of maps of dust sources retrieved from different satellite products. ► Temporal resolution of satellite products is key issue in retrieving dust sources. ► Spatio-temporal distribution depends on observation and start of dust emission.
We present a new dust source area map for the Sahara and Sahel region, derived from the spatiotemporal variability of composite images of Meteosat Second Generation (MSG) using the 8.7, 10.8 and 12.0 ...μm wavelength channels for March 2006–February 2007. Detected dust events have been compared to measured aerosol optical thickness (AOT) and horizontal visibility observations. Furthermore the monthly source area map has been compared with the Ozone Monitoring Instrument aerosol index (AI). A spatial shift of the derived frequency patterns and the local maxima of AI‐values can be explained by wind‐transport of airborne dust implicitly included in the AI signal. To illustrate the sensitivity of a regional model using the new dust source mask, we present a case study analysis that shows an improvement in reproducing aerosol optical thickness in comparison to the original dust source parameterization.
Fifteen‐minute Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) infrared dust index images are used to identify dust source areas. The observations of dust ...source activation (DSA) are compiled in a 1° × 1° map for the Sahara and Sahel, including temporal information at 3‐hourly resolution. Here we use this data set to identify the most active dust source areas and the time of day when dust source activation occurs most frequently. In the Sahara desert 65% of DSA (March 2006 to February 2008) occurs during 0600–0900 UTC, pointing toward an important role of the breakdown of the nocturnal low‐level jet (LLJ) for dust mobilization. Other meteorological mechanisms may lead to dust mobilization including density currents initiated by deep convective systems which mobilize dust fronts (haboobs) occurring preferentially in the afternoon hours and cyclonic activities. The role of the nocturnal LLJ for dust mobilization in the Sahara is corroborated by regional model studies and analysis of meteorological station data.
Video-assisted thoracoscopic surgery (VATS) lobectomy has been shown to be a safe, minimally invasive approach for the surgical management of lung cancer. Despite evidence supporting oncologic ...efficacy, recent reports indicate that less than half of lobectomies are performed by VATS. We examined nationwide lobectomy practice patterns to identify specific predictors for VATS adoption.
Premier hospital data (2010 to 2014) were used to identify open and VATS lobectomy procedures performed for the treatment of primary lung cancer. Propensity score method was used to match VATS and open operations (1:1) on clinical characteristics. Variables associated with VATS lobectomy were assessed by logistic regression to evaluate independent predictors. Secondary outcomes included postoperative complications, readmission, and mortality.
Patients with primary lung cancer (n = 17,304) that underwent VATS (n = 6,670, 38.5%) or open (n = 10,634, 61.5%) lobectomy were identified; 6,670 patients in each group were matched for analysis. VATS performance increased significantly from 2010 to 2014, (39.6% versus 43.8%, p = 0.0004), particularly for thoracic surgeons (50.3% versus 54.7%, p < 0.0001), those performing 15 or more lobectomies per year (53.6% versus 59.8%, p < 0.0001), and for surgeons practicing in the Northeast (54.8% versus 59.9%, p = 0.0001). Independent predictors of VATS utilization included surgeon volume and specialty training, hospital type and size, and region. Multivariate analysis demonstrated a significant association between VATS and surgeon volume, independent of specialty.
National rates of VATS lobectomy continue to increase, particularly for thoracic surgeons, high-volume surgeons, and surgeons in the Northeast. Surgeon volume and specialty are strong independent predictors of VATS lobectomy. Efforts that support centralization of care may improve VATS lobectomy rates and decrease the regional variability identified in this analysis.
Thoracic esophageal diverticula are uncommon, and controversies exist regarding their management. The objective of this study was to evaluate the outcomes of a relatively large cohort of patients ...with thoracic esophageal diverticula treated with minimally invasive surgical techniques.
We conducted a retrospective review of patients who underwent minimally invasive surgical treatment for symptomatic esophageal diverticula during a 15-year period. The primary end point was 30-day mortality. In addition, we evaluated the morbidity, improvement in dysphagia (score: 1, best to 5, worst), and quality of life (Gastroesophageal Reflux Disease-Health-Related Quality of Life score: 0, best to 50, most symptoms).
Fifty-seven patients underwent minimally invasive surgical treatment of symptomatic thoracic esophageal diverticula. The most common symptom was dysphagia (45 of 57; 79%). A motility disorder or distal mechanical obstruction was identified in 49 patients (86%). Approaches used included video-assisted thoracoscopic surgery (n = 33), laparoscopy (n = 18), and combined video-assisted thoracoscopic surgery and laparoscopy (n = 6). The most common procedure performed was diverticulectomy and myotomy (47 of 57 patients; 82.5%). The 30-day mortality was 0%. There were 4 patients (7%) with postoperative leaks requiring reoperation. During follow-up, the median dysphagia score improved from 3 to 1 (p < 0.001). The median Gastroesophageal Reflux Disease-Health-Related Quality of Life score after surgery was 5 (excellent).
A minimally invasive surgical approach for the management of thoracic esophageal diverticula is safe and effective during intermediate-term follow-up when performed by surgeons experienced in esophageal surgery and minimally invasive techniques. Further follow-up is required to assess the durability of these results. The optimal approach and procedures performed should be determined on an individualized basis after a thorough investigation.
The paper presents the current status of the Maritime Aerosol Network (MAN), which has been developed as a component of the Aerosol Robotic Network (AERONET). MAN deploys Microtops handheld Sun ...photometers and utilizes the calibration procedure and data processing (Version 2) traceable to AERONET. A web site dedicated to the MAN activity is described. A brief historical perspective is given to aerosol optical depth (AOD) measurements over the oceans. A short summary of the existing data, collected on board ships of opportunity during the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project is presented. Globally averaged oceanic aerosol optical depth (derived from island‐based AERONET measurements) at 500 nm is ∼0.11 and Angstrom parameter (computed within spectral range 440–870 nm) is calculated to be ∼0.6. First results from the cruises contributing to the Maritime Aerosol Network are shown. MAN ship‐based aerosol optical depth compares well to simultaneous island and near‐coastal AERONET site AOD.
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