Relationship and its instability of ENSO — Chinese variations in droughts and wet spells
Tóm tắt
Monthly data of Self-Calibrated Palmer Drought Severity Index (PDSI) from 1951 to 2000 are calculated using historical precipitation and temperature data for Chinese 160 stations. Temporal and spatial patterns of the first empirical orthogonal function (EOF) of the PDSI reveals a fairly linear trend resulting from trends in precipitation and surface temperature, which is similar to the linear PDSI trend during 1951–2000 calculated using all monthly data. The EOF analysis also reveals that the leading mode correlates significantly with ENSO events in time and space. The ENSO EOF shows that during the typical warm phase of ENSO, surface conditions are drier in most regions of China, especially North China, but wetter than normal in the southern regions of Changjiang River, and Northwest China. During the typical cold phase of ENSO, these anomalies reverse sign. From 1951 to 2000, there are large multi-year to decadal variations in droughts and wet spells over China, which are all closely related to strong El Niño events. In other words, when one strong El Niño event happens, there is a possible big variability in droughts and wet spells over China on the multi-year or decadal scale. Studies also suggest that during the last 2–3 decades climate changes over China, especially North China’s drying and northwest China’s wetting, are closely related to the shift in ENSO towards warmer events and global warming since the late 1970s. The instability of the relationship is also studied. It is revealed that there is a good correlation between ENSO and Chinese variations in droughts and wet spells in the 3–8-year band, but the correlation between ENSO and Chinese variations in droughts and wet spells is instable. Studies suggest that there are decadal changes in the correlation: the wavelet coherency between ENSO and Chinese variations in droughts and wet spells is high during 1951–1962 and 1976–1991, but low during 1963–1975 and 1992–2000.
Tài liệu tham khảo
Wang S W. Diagnostic studies on the climate change and variability for the period of 1880–1990. Acta Meteorol Sin (in Chinese), 1994, 52(3): 263–272
Chen L X, Shao Y N, Zhang Q F, et al. The elementary analysis of Chinese climate change during the last forty years. J Appl Meteorol (in Chinese), 1991, 2(2): 164–173
Chen L X, Zhou X J, Li W L, et al. Climate change and its mechanism during the last eighty years. Acta Meteorol Sin (in Chinese), 2004, 62(5): 634–646
Wang S W. Studies on climatic change in China during the last one hundred years. Sci Found of China (in Chinese), 1998, 3: 167–170
Zhai P M, Chao Q C, Zou X K. Progress in China’s climate change study in the 20th century. J Geogr Sci, 2004, 14(suppl.): 3–11
Trenberth K E, Overpeck J T, Solomon. Exploring drought and its implications for The future. Eos, 2004, 85: 27
Wilhite D A. Drought as a natural hazard: Concepts and definitions. In: Wilhite D A, ed., Droughts: A Global Assessment. Routledge, 2000, 3–18
Heim Jr. Drought indices: A review. In: Wilhite D A ed. Droughts: A Global Assessment. Routledge, 2000, 159–167
Palmer W C, Meteorological drought research paper, No.45, US Dept. of Commerce, 1965
Dai A, Trenberth K E, Karl T R. Global variations in droughts and wet spells: 1900–1995. Geophys Res Lett, 1998, 25: 3367–3370
Dai A, Trenberth K E, Qian T. A global data set of Palmer Drought Severity Index for 1870–2002: Relationship with soil moisture and effects of surface warming. J Hydrometeorol, 2004, 5: 1117–1130
Wei J, Tao S Y, Zhang Q Y. Analysis of drought in north China Based on the Palmer severity drought index. Acta Geogra Sin (in Chinese), 2003, 58(Suppl.): 091–099
Wei J, Zhang Q Y, Tao S Y. Characteristic of atmosphere circulation anomalies during persistent droughts in north China for last two decades. J Appl Meteorol (in Chinese), 2003, 14(2): 140–151
Liu Y Q, Ding Y H. The influence of ENSO events on seasonal precipitation and temperature in China. Chin J Atmos Sci (in Chinese), 1995, 19(2): 200–208
Lu R J, Zhang X G. The response characteristic of precipitation and temperature to ENSO. J Appl Meteorol (in Chinese), 1995, 6(1): 119–123
Trenberth K E, Signal versus noise in the Southern Oscillation. Monthly Weather Rev, 1984, 112: 326–332
Alley W M. Palmer drought severity index: limitations and assumptions. J Clim Appl Meteorol, 1984, 23: 1100–1109
Heddinghause, Thomas R, Sabol P. A review of the Palmer Drought Severity Index and where do we go from here. In: Proceedings of the Seventh Conference on Applied Climatology, 1991. 242–246
Research Group of “Study on Water Stress and Drought in North China Plain”. Research on Crop Water Stress and Drought. Zhengzhou: Henan Science and Technology Press, 1991. 175–214
Wei J, Ma Z G. Comparison of PDSI, percentage of precipitation anomaly and surface humid index. Acta Geogr Sin (in Chinese), 2003, 58(Suppl.): 117–124
Nathan W, Michael J H. A self-calibrating Palmer drought severity index. J Climate, 2004, 6: 2335–2351
Ropelewski C F, Halpert M S, Global and regional scale precipitation patterns associated with the El-Niño Southern Oscillation. Mon Wea Rev, 1987, 115: 1606–1626
Dai A G, Wigley, Global patterns of ENSO-induced precipitation. Geophys Res Lett, 2000, 27: 1283–1286
Trenberth K E, Caron J M. The Southern Oscillation revisited: Sea level pressures, surface temperatures, and precipitation. J Climate, 2000, 13: 4358–4365
Kiladis G N, Diaz H F. Global climatic anomalies associated with extremes in the Southern Oscillation. J Climate, 1989, 2: 1069–1090
Li C Y. Introduction of Climatic Dynamic. Beijing: Meteorology Press, 2000. 257–258
Monahan A H, Dai A. The spatial and temporal structure of ENSO nonlinearity. J Climate, 2004, 17: 3026–3036
Chen W. Impacts of El Niño and La Niña on the cycle of the east Asian winter and summer monsoon. Chin J Atmos Sci (in Chinese), 2002, 26(5): 595–610
Trenberth K E, Hoar T J. The 1990–1995 El Niño-Southern Oscillation event: longest on record. Geophys Res Lett, 1996, 23: 57–60
Trenberth K E, Hoar T J. El Niño and climate change. Geophys Res Lett, 1997, 24: 3057–3060
Huang R H, Xu Y H, Zhou L T. The interdecadal variation of summer precipitations in China and the drought trend in north China. Plateau Meteorology (in Chinese), 1999, 18(4): 465–476
Wang H J. Instability of the East Asian summer monsoon-ENSO relations. Adv Atmos Sci, 2002, 19(2): 1–11
Torrence C, Webster P J. Interdecadal changes in the ENSO-Monsoon system. J Climate, 1999, 12: 2679–2690
Grinsted A, Jevrejeva S, Moore J. Application of the cross wavelet transform and wavelet coherence to geophysical time series. Nonlinear Proc Geophys, 2004, 11: 561–566