WAbalos Undae is a dune field on Mars in the periphery of Planum Boreum, the Martian North pole. It is one of the officially named northern circumpolar dune fields, along with Olympia, Hyperboreae, and Siton Undae, and also one of the densest of the region. Its northernmost boundary is located in the southwest channel that separates the Abalos Colles formation from the main polar ice cap, and from there the dune field extends southwest all the way to the lowlands of Vastitas Borealis.
WAspledon Undae is one of the named northern circumpolar dune fields in the vicinity of Planum Boreum, the Martian North pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by the International Astronomical Union (IAU) on 20 March 2007. Its name is Greek, and derives from the name of a town in Boeotia, Ancient Greece, which, in turn, took its name from Aspledon, son of Poseidon, the ancient Greek god of the sea. The dunes of Aspledon Undae extend from latitude 71.47°N to 75.14°N and from longitude 305.83°E to 315.04°E. Its centre is located at latitude 73.06°N, longitude 309.65°E (50.35°W), and has a diameter of 215.2 km.
WHagal is the informal name of a dune field on Mars located below the north pole of Mars. Its name derives from the sand dunes in Frank Herbert's novel Dune and the fictional planet Hagal. It is located at coordinates 78.0° N latitude, 84.0° E longitude, and consists of linear and round dunes with a southeast slipface orientation. It was one of the dune formations targeted for imaging by the HiRISE camera, on board the Mars Reconnaissance Orbiter, at the rate of one image every six weeks. in the third year of its seasonal expedition. It is also known as the "Martian Morse Code" due to the linear and rounded formations of its dunes, which have the appearance of dots and dashes.
WHyperboreae Undae is one of the largest and densest dune fields of Planum Boreum, the Martian North Pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU in 1988. It extends from latitude 77.12°N to 82.8°N and from longitude 302.92°E to 316.02°E. Its centre is at latitude 79.96°N, longitude 49.49°W, and has a diameter of 463.65 kilometres (288.10 mi).
WNili Patera is a dune field on Mars. It is located on top of a lava bed, at the site of an ancient volcano, the Nili Patera caldera of Syrtis Major, near the Martian equator, and it is one of the most active dune fields of Mars. Its location coordinates on Mars are 8.7° N latitude, 67.3° E longitude. It is being actively studied by the HiRISE camera, on board the Mars Reconnaissance Orbiter, at the rate of one image every six weeks. The study of the movement of the dunes provides information regarding wind variation as a function of time and furthers the study of surface erosion characteristics of the Martian landscape. This information can then be used for the development and design of future Mars expeditions. The dunes of the Patera field are of the barchan type and their study by HiRISE was the first one to establish dune and ripple movement of a minimum of 1 metre on Mars. The Patera dune field, was also the first to be investigated using the COSI-Corr software, which was originally developed to analyse the movement of earthbound dunes. The research results from the evidence provided by the monitoring of the Nili Patera field, indicate sand fluxes of the order of several cubic metres per metre per year, similar to the flux observed at the sand dunes of Victoria Valley in Antarctica.
WOgygis Undae is the only named southern hemisphere dune field on Mars. It is named after one of the classical albedo features on Mars, Ogygis Regio. Its name, which refers to Ogyges, a primeval mythological ruler in ancient Greece, was officially approved by the International Astronomical Union (IAU) on September 17, 2015. It is situated just outside Argyre Planitia, a plain located in the southern highlands of Mars. The dunes of Ogygis Undae extend from latitude −49.94°N to −49.37°N and from longitude 292.64°E to 294.93°E. They are centered at latitude −49.66°N, longitude 293.79°E (66.21°W), and extend approximately 87 km to the east and west from there. Ogygis Undae has an area of 1904 km2, and due to its large size is a primary subject for research on Martian dune morphology and sand composition.
WOlympia Undae is a vast dune field in the north polar region of the planet Mars. It consists of a broad "sand sea" or erg that partly rings the north polar plateau from about 120° to 240°E longitude and 78° to 83°N latitude. Stretching about 1,100 km (680 mi) across and covering an area of 470,000 km2, Olympia Undae is the largest continuous dune field on Mars. It is similar in size to the Rub' Al Khali in the Arabian Peninsula, the largest active erg on Earth.
WSiton Undae is one of the largest and densest dune fields in the vicinity of Planum Boreum, the Martian northern polar ice-cap. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU on 20 March 2007. It extends from latitude 73.79°N to 77.5°N and from longitude 291.38°E to 301.4°E. Its centre is located at latitude 75.55°N, longitude 297.28E (62.72°W), and has a diameter of 222.97 kilometres (138.55 mi).