Zuber M T, Smith D E, Solomon S C, Abshire J B, Afzal R S, Aharonson O, Fishbaugh K, Ford P G, Frey H V, Garvin J B, Head J W, Ivanov A B, Johnson C L, Muhleman D O, Neumann G A, Pettengill G H, Phillips R J, Sun X, Zwally H J, Banerdt W B, Duxbury T C
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 1998 Dec 11;282(5396):2053-60. doi: 10.1126/science.282.5396.2053.
Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography.
火星轨道激光高度计（MOLA）的数据被用于构建火星北极地区精确的地形图。北极冰盖比周围环境高出3千米，但位于一个5千米深的半球形凹陷内，该凹陷与大多数外流河道汇入的区域相连。极冠地形显示出被消融、流动和风改造的迹象，并且与主要由水冰构成的成分相一致。地形与图像的相关性表明，过去极冠在空间上更为广阔。极冠的体积为1.2×10⁶至1.7×10⁶立方千米，约为格陵兰冰盖体积的一半。在极冠上方观测到的云可能由北半球冬季从大气中凝结出来的二氧化碳组成。许多云呈现出动态结构，这可能是由传播的波前与地表地形相互作用引起的。
