Mi Desheng
The map of snow, ice and frozen ground in China is a 115×80 cm2 wall map (1:4000000) showing the distribution of some special phenomena in cold regions, including seasonal snow cover, sea ice lake ice and river ice, glacier, frozen ground and other cryogenic (periglacial) features. It also shows the present solid water resource and the relation of above features to mankind. The appearance and variation of above features is complicated and related to mankind and also related each other.In cartographical generalization of this map, the following points are considered.(l)The colour matching should be coincident with the climate characteristics of the cold and high regions. Cold colour is the primary and warm colour is the subsidiary. The tonalitus of blue, purple and grey are for the cold and dry mountains in the West China and the Qinghai-Xizang Plateau; cold and wet colour, mainly purple and grey for the Northeast China. It is warm and rainy in the southeast, so the tonality is selected to be apple green. It is coloured in block to keep the map simple, elegant, clear and harmonious.(2)Snow cover, glacier and frozen ground are generalized based on their classification and graduation. Editors pay much attention to-ensuring both the practicability of this map and the correctness of its content in science.Existing (modern) glacier Ice tongues and firn fields greater than 10 km, snow lines and their elevations are marked on the map. Mountain glaciers are outlined on the map proportionally in order to evaluate correctly the solid water resource. The small zigzags of glaciated regions are smoothed, the morphological character of typical glaciers are inflated, and boundaries between different types of glaciers are prominent in condition of keeping the natural situation of glacier distribution. Positions of mud-debris flows caused by melting of glacial ice and bursting of glacial lake are shown with different symbols. Same symbol is used to show the freezing days and thickness of sea ice, river ice and lake ice. If the symbol is in a lake then it shows the freezing character of lake ice, and so on. The blue dotted lines show the drifting extent of sea ice.Seasonal snow cover The mean annual values of snow cover existing days are annotated. If snow cover exists 50 days or more within a year then it is defined as a stable snow cover region, otherwise the unstable one. The mean annual value of snow coverequation is expressed by blue line with an annotation showing the value in days. The isopleth of 50-60 days is thickened. Wind-blown drifting snow and avalanche are marked with red symbols in different shapes.Frozen ground Permafrost is divided into two broad categories. The high-latitude permafrost in the Northeast China is subdivided into three which are shown by blue grey coloured hachure lines in different densities. The high-altitude permafrost is subdivided into plateau and alpine permafrosts which are expressed by purple brown coloured hachure lines in different densities. Bore holes for observation of permafrost are expressed by red coloured symbols with numeral annotation showing the mean annual ground temperature and permafrost thickness. The seasonally frozen ground is shown by apple green coloured ones, they are in same density. Editors give prominence to the expressing of the 0.5 m-isopach of seasonally frozen ground.(3)According to their morphological characters, approximately 14 typical cryogenetic (periglacial) phenomena positions caused by frost weathering, gelifluction, frost sorting, frost heaving and thermokarst are shown by corresponding representational symbols.Legends of seasonal snow cover, mountain glacier, frozen ground and cryogenetic phenomena are exhibited on the lower left side with a Chinese-English bilingual description.
