09May/21

Photogrammetry as a research tool for glaciology

first_imgUsing a multidisciplinary project studying surging glaciers in Svalbard as a reference, this paper examines some of the ways in which photogrammetry can be used as a research tool by glaciologists. Photogrammetric compilations of two of the glaciers under study were produced from 1990 aerial photography. Photogrammetry was regarded primarily as a source of digital elevation models in this project, rather than as a cartographic tool. Problems encountered in applying photogrammetry to the arctic terrain are considered and a methodology devised to ameliorate these problems by maximizing the available data is described. The results of the photogrammetric work are presented and difficulties in quantifying the accuracy of the photogrammetric data are examined. Examples of the ways in which the photogrammetrically derived digital data have been used for glaciological analysis and visualization are discussed.last_img read more

09May/21

The dynamics of idealized katabatic flow over a moderate slope and ice shelf

first_imgA non-hydrostatic numerical weather prediction model has been employed to Simulate idealized katabatic flows over a moderate slope and adjoining ice shelf. The topography of Coats Land and the adjoining Brunt Ice Shelf. Antarctica. has been used: this is typical of much of the Antarctic coastline. The Regional Atmospheric Modeling System Version 4.3 has been adapted for simulations over compacted snow, most notably through changes to the multi-layer soil model. The Simulations are initialized using clear-sky conditions and at rest. On the slope. a shallow katabatic flow develops, the winds becoming approximately steady on the slope by similar to12 h. The peak downslope winds are about 7 m s(-1) at 30 m above the snow surface. The katabatic flow depth ranges from 50 to 100 m down the slope. Over the ice shelf the katabatic flow peters out, while a pool of cold air develops, primarily through sensible-heat loss into the surface and partially balancing the net radiative-heat loss to space. Near-surface and Sounding data from the model simulations compare well with archetypal and typical katabatic flow observations. especially after some tuning of the model’s turbulence parametrization. An analysis of the downslope flow dynamics shows the buoyancy force is generally balanced by the inertial force. except towards the foot of the slope where it is balanced by upslope forces related to gradients in the potential-temperature deficit and katabatic-layer height. caused by the pool of cold air over the ice shelf. Over time, the cooling of the ice shelf boundary layer leads to an apparent retreat of the katabatic flow from the ice shelf and some way up the slope. The dynamical analysis explains the surface climatology observed, such that the persistent katabatic winds of Coats Land rarely reach the Brunt Ice Shelf. The simulated katabatic flow moves from ‘shooting’ to ‘tranquil’ towards the foot of the slope. This transition acts to trigger a train of internal gravity waves which propagate energy upwards away from the katabatic flow JUMP. Previous studies have also found shooting to tranquil katabatic flow transitions, so to generalize these findings Would suggest that internal gravity-wave generation is ubiquitous around much of coastal Antarctica and Greenland.last_img read more

09May/21

Gyro-resonant electron acceleration at Jupiter

first_imgAccording to existing theory, electrons are accelerated up to ultra-relativistic energies(1) inside Jupiter’s magnetic field by betatron and Fermi processes as a result of radial diffusion towards the planet and conservation of the first two adiabatic invariants(2-4). Recently, it has been shown that gyro-resonant electron acceleration by whistler-mode waves(5,6) is a major, if not dominant(7), process for accelerating electrons inside the Earth’s outer radiation zone, and has redefined our concept for producing the Van Allen radiation belts(8). Here, we present a survey of data from the Galileo spacecraft at Jupiter, which shows that intense whistler-mode waves are observed outside the orbit of the moon Io and, using Fokker-Planck simulations, are strong enough to accelerate electrons to relativistic energies on timescales comparable to that for electron transport. Gyroresonant acceleration is most effective between 6 and 12 jovian radii (R-j) and provides the missing step in the production of intense synchrotron radiation from Jupiter(1,9).last_img read more

09May/21

Ice stream subglacial access for ice sheet history and fast ice flow: The BEAMISH Project on Rutford Ice Stream, West Antarctica and initial results on basal conditions

first_imgThree holes were drilled to the bed of Rutford Ice Stream, through ice up to 2154 m thick, to investigate the basal processes and conditions associated with fast ice flow and the glacial history of the West Antarctic Ice Sheet. A narrative of the drilling, measuring and sampling activities, as well as some preliminary results and initial interpretations of subglacial conditions, is given. These were the deepest subglacial access holes ever drilled using the hot-water drilling method. Samples of bed and englacial sediments were recovered, and a number of instruments were installed in the ice column and the bed. The ice-bed interface was found to be unfrozen, with an existing, well-developed subglacial hydrological system at high pressure, within ∼1% of the ice overburden. The bed itself comprises soft, water-saturated sediments, consistent with previous geophysical interpretations. Englacial sediment quantity varies significantly between two locations ∼2 km apart, and possibly over even shorter (∼20 m) distances. Difficulties and unusual observations encountered while connecting to the subglacial hydrological system in one hole possibly resulted from the presence of a large clast embedded in the bottom of the ice.last_img read more

04May/21

Turkish Naval Forces’ LCT Sets New Speed Record Amid Sea Trials

first_imgBack to overview,Home naval-today Turkish Naval Forces’ LCT Sets New Speed Record Amid Sea Trials View post tag: LCT July 2, 2012 View post tag: record The third vessel of Landing Ship Tanks (LCT) Project, undertaken by ANADOLU Shipyard with the Turkish Under-secretariat of Defense Industries (SSM) for Turkish Naval Forces, namely NB 226 / Ç-153, has set a new speed record while cruising amid sea trials in the Aegean Sea. The vessel at 1,040 tons displacement, with the wind speed of around 20 knots, has reached the velocity of 22 knots.This speed, although it was not realized at full displacement, has set a new record for Landing Craft Tanks (LCT) built by ANADOLU Shipyard.The design speed of ANADOLU Shipyard’s LCT at full displacement has been 18 knots, while during the sea trials the vessel easily achieved a speed of 18.5 knots.Specifications for the LCTs:Length: 79.85mBeam: 11.70Displacement 1155 tons full loadRange: 400 nm / 16 ktsPropulsion: 2 x 2320 kWCrew: 22Cargo: 320 tons / 250 troopIn 2007, Under-secretariat for Defense Industries, submitted a Request for Proposal for 8 LCTs. ANADOLU Shipyard has already delivered the first five vessels of the LCT project.[mappress]Naval Today Staff, July 2, 2012; Image:adik View post tag: trials View post tag: News by topic Share this article View post tag: Naval Turkish Naval Forces’ LCT Sets New Speed Record Amid Sea Trials View post tag: speed View post tag: forces View post tag: Navy Industry news View post tag: sets View post tag: New View post tag: Amid View post tag: Turkish View post tag: sealast_img read more

04May/21

Iranian Navy Thwarts Second Pirate Attack in 24 Hours

first_img View post tag: Naval Iranian Navy Thwarts Second Pirate Attack in 24 Hours January 9, 2014 View post tag: Navy View post tag: Iranian View post tag: News by topic View post tag: attack View post tag: 24% View post tag: Defence View post tag: hours Back to overview,Home naval-today Iranian Navy Thwarts Second Pirate Attack in 24 Hours View post tag: Pirate View post tag: Second ILLUSTRATION: SOMALI PIRATESThe Iranian Navy’s 28th fleet fended off a second pirate attack targeting the country’s ship in the last 24 hours, as reported by the Fars news agency on Jan. 9 citing a Navy source.The pirates aboard 8 boats were approaching another Iranian ship in the waters of the Gulf of Aden this morning trying to seize it .Twenty four hours ago, another attack was prevented when twelve pirate boats attacked an oil tanker at the same location.With the help from the Iranian Navy the ship was successfully defended.The Iranian Navy continues operating in the Gulf of Aden, securing the country’s ships from pirate attacks.[mappress]Naval Today Staff, January 09, 2014; Image: Usni View post tag: Defense Share this article View post tag: Thwartslast_img read more

04May/21

USS Stout Halfway Through Her Deployment

first_img USS Stout Halfway Through Her Deployment Back to overview,Home naval-today USS Stout Halfway Through Her Deployment December 31, 2013 USS STOUT AT SEAArleigh Burke-class guided-missile destroyer USS Stout (DDG 55) recorded the halfway point of her deployment to the U.S. 6th Fleet area of operation in Limassol, Dec. 24.Since departing her homeport in Norfolk, Va., the ship has supported ballistic missile defense in the Mediterranean, participated in three multinational exercises, and maintained an active and vital presence in the area.As explained by Cmdr. Robert Alpigini, Stout’s commanding officer, it is important to recognize the halfway point as a way to pause for reflection on the accomplishments thus far and at the same time celebrate the holidays.The holiday festivities on the ship began on the mess decks with a large meal prepared by the ship’s culinary specialists.After the meal, the entire crew gathered together on the flight deck for a large gift exchange. A number of organizations like Soldiers Angels, Project Santa, Jim and Rita Toepfer, Project Package, Vietnam Veterans of America and many more donated food, stockings, games, candy, cards, stuffed animals and a variety of other gifts so that each Sailor could open something.[mappress]Press Release, December 31, 2013; Image: Wikimedia View post tag: News by topic View post tag: Defence View post tag: Defense View post tag: Her View post tag: Halfwaycenter_img View post tag: USS View post tag: Naval View post tag: through View post tag: Deployment View post tag: Stout View post tag: Navy Share this articlelast_img read more

04May/21

HMAS Stirling Prepares for the Biggest ANZAC Day

first_imgBack to overview,Home naval-today HMAS Stirling Prepares for the Biggest ANZAC Day View post tag: Anzac View post tag: day View post tag: prepares Share this article Personnel have been practising their drill in the lead up to the day and Commanding Officer of Stirling Captain Angela Bond says she is impressed with everyone’s commitment to ensuring professional representation.“Collectively the personnel here at Stirling have rehearsed approximately 30 hours in the lead up. That sort of commitment demonstrates how important this day is to serving personnel.“We are supporting ANZAC Day activities in 22 locations; one-sixth of the Navy’s personnel are based here so spreading that footprint across the local area and wider Perth demonstrates our engagement with the community in Western Australia.“To me personally, ANZAC Day is a day for reflecting on our returned and fallen service men and women as well as honouring current serving members.“It is always a big day and the dedication of the gunnery department here has been impressive. As the subject matter experts they have trained and supported the rest of the Fleet Base West personnel in their training and I have no doubt that their hard work will be proudly demonstrated across the greater Perth area tomorrow,” said Captain Bond.Next year, in the 100th year of Submarines in Australia, the crews of HMA Submarines Dechaineaux, Sheean, Farncomb and Waller will lead the ANZAC Day Parade in Perth. Submarine support elements will march in Fremantle and a selection Stirling personnel will march in Rockingham and Cockburn.Other locations Stirling people will support include the small town of Pengally almost three hours away from Perth and Joondalup north of Perth. Smaller representation of Stirling personnel will also be evident in a number of country towns and locations throughout the greater Perth area. HMAS Sirius ship’s company will march in Mandurah, south of Perth.[mappress]Press Release, April 24, 2014; Image: Australian Navy View post tag: Navy April 24, 2014 HMAS Stirling Prepares for the Biggest ANZAC Daycenter_img Training & Education View post tag: Naval View post tag: biggest View post tag: News by topic View post tag: Stirling HMAS Stirling is preparing for the biggest ANZAC Day yet in the 99th year since the Gallipoli campaign. Personnel from HMAS Stirling, Fleet Base West units and lodger units will be honouring the special day in locations across Western Australia. View post tag: HMASlast_img read more

04May/21

Future USS Daniel Inouye Launched

first_img View post tag: Bath Iron Works Authorities View post tag: Navy View post tag: launched Bath Iron Works (BIW) celebrated the start of fabrication of the future USS Daniel Inouye (DDG 118) during a ceremony at BIW shipyard, Oct. 31.This first major ship milestone symbolizes that the first 100 tons of steel for the ship have been cut.Capt. Mark Vandroff, DDG 51-class program manager, Program Executive Office (PEO) Ships, said:Construction on Arleigh Burke-class (DDG 51) destroyers is in full swing on the East and Gulf Coasts.The restart DDG 51s benefit from a mature and stable design with increased air and missile defense capabilities. These build on a legacy of success, providing outstanding combat capability and survivability characteristics.The ceremony came just a day after BIW ceremoniously laid the keel for the future USS Rafael Peralta (DDG 115), and a month following the start of fabrication on the future USS Paul Ignatius (DDG 117) at the Huntington Ingalls Industries (HII) shipyard in Pascagoula, Mississippi.Daniel Inouye will be equipped with the Navy’s Aegis Combat System, the world’s foremost integrated naval weapon system. This system delivers quick reaction time, high firepower, and increased electronic countermeasures capability for anti-air warfare.The ship is part of the Navy’s latest flight of destroyer, Flight IIA, which enables power projection, forward presence, and escort operations at sea in support of low intensity conflict/coastal and littoral offshore warfare as well as open-ocean conflict.[mappress mapid=”14284″]Press release, Image: US Navy Future USS Daniel Inouye Launched View post tag: americas View post tag: futurecenter_img Back to overview,Home naval-today Future USS Daniel Inouye Launched November 3, 2014 View post tag: Naval View post tag: News by topic View post tag: USS Daniel Inouye Share this articlelast_img read more

04May/21

INS Sukanya Enters Port of Colombo

first_imgBack to overview,Home naval-today INS Sukanya Enters Port of Colombo December 9, 2014 Share this article View post tag: asia View post tag: Port of Colombo The Indian Naval Ship “Sukanya” arrived at the Port of Colombo for logistic support on 09th December 2014. It was welcomed by the Sri Lanka Navy in accordance with naval traditions on arrival.The ship’s Commanding Officer Commander MD Dorai Babu paid a visit to the Deputy Area Commander of the Western Naval Area Commodore KG Paul of the Sri Lanka Navy at the Western Naval Command Headquarters in Colombo. They held cordial discussions and exchanged mementos as a gesture of goodwill.“Sukanya” is an Offshore Patrol Vessel of the Indian Navy with a displacement of 1,890 tones. It is 101.1m in length and consists of a complement of 165 naval personnel onboard. The ship will remain in Sri Lanka until 12th December 2014.[mappress mapid=”14660″]Press release, Image: Sri Lanka Navy View post tag: enters Authorities View post tag: Naval INS Sukanya Enters Port of Colombo View post tag: News by topic View post tag: Navy View post tag: INS Sukanyalast_img read more