Reconstruction of Summer Sea Level Pressure over East Asia since 1470

Abstract

close relationship between sea level pressure (SLP) over East Asia and precipitation indices (PIs) in eastern China was observed in the summers (June?August) of 1850?2008 using singular value decomposition (SVD) analysis. To investigate this relationship over a longer period, the SLP fields were reconstructed back to 1470 based on a mathematical model and the historical precipitation indices of eastern China. A cross-validation test of independent samples suggests that the reconstructed SLPs are statistically acceptable. According to the first three predominant SVD modes of the SLP field, three SLP index series (SLPI1?SLPI3) were developed to quantify the thermodynamic differences among the critical SLP centers of East Asia. Both SLPI1 and SLPI2 are highly correlated with the East Asian summer monsoon index, whereas SLPI3 is related to the index of Eurasian meridional atmospheric circulation. The temporal scales of SLP indices were examined during 1470?2008 using the wavelet power spectra. Results indicate that there is significant variance at a 2?5-yr band in the power spectra of the three SLP indices, suggesting SLPI1?SLPI3 have evident interannual variability. Moreover, the wavelet power spectra of SLPI1 and SLPI2 show significantly higher power at the 8?12-yr scale from 1470 to 1750 and at the 60?90-yr scale after 1750. For SLPI3, besides the interannual variability, it has additional periodical variability of 6?11 and 23?33 yr.