Satellite Observations Of Variations In Northern Hemisphere Seasonal Snow Cover

Author : Kenichi Matsui
Publisher :
ISBN 13 :
Total Pages : 156 pages
Book Rating : 4.:/5 (621 download)

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Download or read book Variations and Regional Differences in Northern Hemisphere Snow Cover Frequency written by Kenichi Matsui and published by . This book was released on 2005 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This study analyzes the regional differences in Northern Hemisphere snow variation based on the satellite data from 1966 to 2001 in order to understand the relationship between the earth snow variation and climate change such as global warming. The satellite data are recalculated onto a two degree grid of monthly snow cover frequency from 25 km grid weekly average snow cover data. Because the ground meteorological observation stations are located in densely populated areas such as cities near airports in mid-latitudes and are inevitably influenced by urban climate effects, such as heat island phenomena, this study used the snow cover data based on the satellite observation. The variations of the Northern Hemisphere snow cover frequency in every month show a consistent decreasing trend of snow cover in summer, especially July and August, but not during spring. Previous studies indicate that snow reduction is the most obvious in spring due to a large decline between the early 1980s and early 1990s. However, this large reduction might only be a part of 5-10 year cyclic change in snow variations. The result of analyzing the snow cover frequency variations with Cluster Analysis show the 2 interannual phases, 1) May through September and 2) October through April. In May through September, most of the snow variation is similar regardless of which continent they occur on. On the other hand, in October through April, several large regions show different snow variations. Secular variations in the snow cover frequency indicate that some months have significant trends in snow cover frequency while others do not. In the months with large significant trends, many areas have the downward trend, the most obviously being the Himalayas and Tibet plateau. On the other hand, western North America shows a significant upward trend in many months. Principal component analysis of the snow cover frequency of the 7 to 10 regions in each month, October through April, shows two inverse trends. The two inverse trend components show 1) an inverse trend between the eastern and western halves of either the Eurasian or North American continents and 2) an inverse trend between the Himalayas and the rest of the hemisphere. In addition, the components showing the inverse trend between the eastern and western parts of continents tend to become weaker as approaching March and April. On the other hand, the components showing the inverse trend between the Himalayas and the rest of the hemisphere tend to become stronger as time going from October to April.