このエントリーをはてなブックマークに追加
ID 776
本文ファイル
別タイトル
土壌水分変動とその大気へのインパクト : スリランカにおける事例
著者
Yamanaka, Tsutomu
Kaihotsu, Ichirow
Shimada, Jun
Nandakumar, Vythilingam
キーワード
Soil moisture
Rainfall
Feedback mechanism
Time series analysis
Sri Lanka
抄録(英)
Time series analyses of soil moisture, rainfall, air temperature and other hydrometeorological components observed at inland area of Sri Lanka in 1994 were carried out. Auto-correlation analysis gives a time scale from 10 to 30 days as persistency of soil moisture anomaly, which is considerably small relative to that under midlatitude temperate climate and is shorter than that for atmospheric temperature. Two dominant periodicities are detected from spectral analysis : 45-60-day period (especially for large rainfall and soil moisture at all depths) and 22.5-30-day period (for small rainfall and shallow soil moisture). The two intraseasonal variations are also detected for satellite-remote-sensed outgoing longwave radiation (OLR) over and around Sri Lanka. Band-pass filtered OLR anomaly for the former periodicity propagates from around Sri Lanka to the west and is strengthened through the process of its westward propagation. On the other hand, OLR anomaly for the latter periodic component has its origin at east ocean-region and propagates westward to Sri Lanka. For the 45-60-day period, band-pass filtered anomaly propagates from rainfall to soil moisture, soil temperature, wet-bulb temperature and back to rainfall, indicating a feedback loop. In contrast, propagation of anomaly through hydrometeorological variables is not found for the 22.5-30-day period. These statistical results indicate that external forcing causes the latter periodic and also that the former periodicity is introduced by an enhancement of the latter variation once in its two cycles due to negative feedback between soil moisture and rainfall. The selective enhancement against different periodic variations appears to be associated with characteristic time-scale of the soil moisture persistence.
掲載誌名
広島大学総合科学部紀要. IV, 理系編
27巻
開始ページ
77
終了ページ
93
出版年月日
2001-12
出版者
広島大学総合科学部
寄与者
国立情報学研究所
作成年月日
2006-03-21
ISSN
1340-8364
NCID
SelfDOI
言語
英語
NII資源タイプ
紀要論文
広大資料タイプ
学内刊行物(紀要等)
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
publisher
部局名
総合科学研究科
他の一覧