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سقوط طاغية وقيام أمة : قبعة القذافي
\"قبعة القذافي\" هذه لمحة عن يوم مراسلة صحفية في خضم المعارك الليبية بين نظام القذافي والثوار التي امتدت على مدى أقل من سنة تروي أليكس كراوفورد بالتفصيل الأحداث التي مرت بها وهي تغطي المعارك التي جرت على الأراضي الليبية. تعرضت للموت كثيرا وتم استجوابها من قبل أكثر من وكالة استخبارات وأنقذها الجيش الأميركي من الاعتقال كما أنها تعرضت لاطلاق النار مباشرة، وكانت المراسلة الصحفية البارعة في تغطية أحداث بعض الأماكن الأكثر خطورة في العالم وها هي تخرج منتصرة وكمراسلة لسكاي نيوز في معركة الصحافيين التلفزيونيين.
BOOK
Does the Summer Arctic Frontal Zone Influence Arctic Ocean Cyclone Activity?
Extratropical cyclone activity over the central Arctic Ocean reaches its peak in summer. Previous research has argued for the existence of two external source regions for cyclones contributing to this summer maximum: the Eurasian continent interior and a narrow band of strong horizontal temperature gradients along the Arctic coastline known as the Arctic frontal zone (AFZ). This study incorporates data from an atmospheric reanalysis and an advanced cyclone detection and tracking algorithm to critically evaluate the relationship between the summer AFZ and cyclone activity in the central Arctic Ocean. Analysis of both individual cyclone tracks and seasonal fields of cyclone characteristics shows that the Arctic coast (and therefore the AFZ) is not a region of cyclogenesis. Rather, the AFZ acts as an intensification area for systems forming over Eurasia. As these systems migrate toward the Arctic Ocean, they experience greater deepening in situations when the AFZ is strong at midtropospheric levels. On a broader scale, intensity of the summer AFZ at midtropospheric levels has a positive correlation with cyclone intensity in the Arctic Ocean during summer, even when controlling for variability in the northern annular mode. Taken as a whole, these findings suggest that the summer AFZ can intensify cyclones that cross the coast into the Arctic Ocean, but focused modeling studies are needed to disentangle the relative importance of the AFZ, large-scale circulation patterns, and topographic controls.
Journal Article
Batman by Grant Morrison omnibus
\"One of the greatest storytellers of his generation, Grant Morrison's arrival onto the Dark Knight was one of the most hyped debuts in industry history. This collection includes time-spanning epic graphic novels featuring the cataclysmic events of FINAL CRISIS and the introduction of Batman's son, Damian Wayne! These blockbuster stories featured a deconstruction of super hero comics like never before, with challenging, thought-provoking takes on the modern, four-color icons.\"-- Provided by publisher.
Book
Sea Ice Loss and Arctic Cyclone Activity from 1979 to 2014
Extensive summer sea ice loss has occurred within the Beaufort, Chukchi, East Siberian, and Laptev Seas over the last decade. Associated anomalies in sensible and latent heat fluxes in autumn have increased Arctic atmospheric precipitable water and air temperatures, with the potential to impact autumn and winter cyclone activity. To examine if a connection exists between recent Arctic sea ice loss and cyclone activity, several cyclone metrics from 60° to 90°N are analyzed. Results show that following years with less September sea ice, there is a subsequent increase in moisture availability, regional baroclinicity, and changes in vertical stability that favor cyclogenesis. However, tracking of individual cyclones indicates no coherent increase in cyclone frequency or intensity associated with sea ice loss. Furthermore, no robust northward progression of extreme cyclones is observed.
Journal Article
Autumn pauses in Arctic-wide sea-ice expansion
In a typical year, Arctic sea-ice extent (SIE) exhibits uninterrupted growth in autumn (October–December), but on some rare occasions (13 times 1979–2023), that expansion has paused for at least 6 days. Eleven of 13 autumn pause events are characterized by net ice loss in the Barents and Kara Seas. The common driver of this loss is the passage of a series of anomalously strong extratropical cyclones into the East Greenland Sea, bringing strong southerly or southeasterly winds into the Barents and Kara Seas, pushing the ice edge polewards and inhibiting additional growth. Temporal clustering of cyclone tracks and the intensity of the southerly flow is often coincident with exceptional high pressure and blocking to the east (the Kara Sea or western Russia). In four cases, sea-ice loss in the Nordic seas is combined with similar atmospheric anomalies in the Pacific sector. Autumn expansion pauses are as common today as in the past because of two competing regime shifts that occurred in 2005: the average autumn SIE expansion rate is now faster, but that expansion rate is also more variable since thinner ice is more responsive to atmospheric anomalies.
Journal Article
Reduced Sea Ice Enhances Intensification of Winter Storms over the Arctic Ocean
The ideal environment for extratropical cyclone development includes strong vertical shear of horizontal wind and low static stability in the atmosphere. Arctic sea ice loss enhances the upward flux of energy to the lower atmosphere, reducing static stability. This suggests that Arctic sea ice loss may facilitate more intense storms over the Arctic Ocean. However, prior research into this possibility has yielded mixed results with uncertain cause and effect. This work has been limited either in scope (focusing on a few case studies) or resolution (focusing on seasonal averages). In this study, we extend this body of research by comparing the intensification rate and maximum intensity of individual cyclones to local sea ice anomalies. We find robust evidence that reduced sea ice in winter (December—March) strengthens Arctic cyclones by enhancing the surface turbulent heat fluxes and lessening static stability while also strengthening vertical shear of horizontal wind. We find weaker evidence for this connection in spring (April—June). In both seasons, lower sea ice concentration also enhances cyclone-associated precipitation. Although reduced sea ice also weakens static stability in September/October (when sea ice loss has been especially acute), this does not translate to stronger storms because of coincident weakening of wind shear. Sea ice anomalies also have little or no connection to cyclone-associated precipitation in these months. Therefore, future sea ice reductions (e.g., related to delayed autumn freeze-up) will likely enhance Arctic cyclone intensification in winter and spring, but this relationship is sensitive to simultaneous connections between sea ice and wind shear.
Journal Article
The Response of Extratropical Cyclone Propagation in the Northern Hemisphere to Global Warming
Extratropical cyclones (ETCs) are a common source of natural hazards, from heavy rain to high winds, and the direction and speed of ETC propagation influence where impacts occur and for how long. Eighteen models from phase 6 of the Coupled Model Intercomparison Project (CMIP6) are used to examine the response of Northern Hemisphere ETC propagation to global warming. In winter, simulations show that ETCs become slower over North America and the Arctic but faster over the Pacific Ocean and part of Europe. In summer, storm propagation becomes slightly slower throughout much of the midlatitudes (30°–60°N). Trends in both seasons relate closely to the impact of global warming on upper-level (250 hPa) winds and the 850–250-hPa thickness gradient. Wherever local thickness gradients weaken in the future, ETCs travel more slowly; conversely, wherever they strengthen, ETCs travel more quickly. In contrast to past work, we find that winter storm propagation becomes more zonal over the Pacific and Atlantic Oceans, which may link to decreased atmospheric blocking and less-sinuous flow at 500 hPa. The importance of model projections of the 850–250-hPa thickness gradient for meridionality of ETC propagation remains uncertain for these regions. However, for North America, models that project stronger thickness gradients also project less-sinuous flow and more-zonal ETC propagation. Overall, this work highlights strong regional variation in how the speed and direction of ETC propagation, and the upper-level circulation patterns that govern them, respond to continued warming.
Journal Article
Arctic open-water periods are projected to lengthen dramatically by 2100
The shrinking of Arctic-wide September sea ice extent is often cited as an indicator of modern climate change; however, the timing of seasonal sea ice retreat/advance and the length of the open-water period are often more relevant to stakeholders working at regional and local scales. Here we highlight changes in regional open-water periods at multiple warming thresholds. We show that, in the latest generation of models from the Coupled Model Intercomparison Project (CMIP6), the open-water period lengthens by 63 days on average with 2 °C of global warming above the 1850-1900 average, and by over 90 days in several Arctic seas. Nearly the entire Arctic, including the Transpolar Sea Route, has at least 3 months of open water per year with 3.5 °C warming, and at least 6 months with 5 °C warming. Model bias compared to satellite data suggests that even such dramatic projections may be conservative.
Journal Article
Sources of seasonal sea-ice bias for CMIP6 models in the Hudson Bay Complex
The seasonal ice-free period in the Hudson Bay Complex (HBC) has grown longer in recent decades in response to warming, both from progressively earlier sea-ice retreat in summer and later sea-ice advance in fall. Such changes disrupt the HBC ecosystem and ice-based human activities. In this study, we compare 102 simulations from 37 models participating in phase 6 of the Coupled Model Intercomparison Project to the satellite passive microwave record and atmospheric reanalyses. We show that, throughout the HBC, models simulate an ice-free period that averages 30 d longer than in satellite observations. This occurs because seasonal sea-ice advance is unrealistically late and seasonal sea-ice retreat is unrealistically early. We find that much of the ice-season bias can be linked to a warm bias in the atmosphere that is associated with a southerly wind bias, especially in summer. Many models also exhibit an easterly wind bias during winter and spring, which reduces sea-ice convergence on the east side of Hudson Bay and impacts the spatial patterns of summer sea-ice retreat. These results suggest that, for many models, more realistic simulation of atmospheric circulation would improve their simulation of HBC sea ice.
Journal Article
Sensitivity of Northern Hemisphere Cyclone Detection and Tracking Results to Fine Spatial and Temporal Resolution using ERA5
Lagrangian detection and tracking algorithms are frequently used to study the development, distribution, and trends of extratropical cyclones. Past research shows that results from these algorithms are sensitive to both spatial and temporal resolution of the gridded input fields, with coarser resolutions typically underestimating cyclone frequency by failing to capture weak, small, and short-lived systems. The fifth-generation atmospheric reanalysis from the European Centre for Medium-Range Weather Forecasts (ERA5) offers finer resolution, and therefore more precise information regarding storm locations and development than previous global reanalyses. However, our sensitivity tests show that using ERA5 sea-level pressure fields at their finest possible resolution does not necessarily lead to better cyclone detection and tracking. If a common number of nearest neighbors is used when detecting minima in sea-level pressure (like past studies), finer spatial resolution leads to noisier fields that unrealistically break up multi-center cyclones. Using a common search distance instead (with more neighbors at finer resolution) resolves the issue without smoothing inputs. Doing this also makes cyclone frequency, lifespan, and average depth insensitive to refining spatial resolution beyond 100 km. Results using 6-h and 3-h temporal resolutions have only minor differences, but using 1-h temporal resolution with a maximum allowed propagation speed of 150 km h -1 leads to unrealistic track splitting. This can be counteracted by increasing the maximum propagation speed, but modest sensitivity to temporal resolution persists for several cyclone characteristics. Therefore, we recommend caution if applying existing algorithms to temporal resolutions finer than 3-h and careful evaluation of algorithm settings.
Journal Article