title: "Intrinsic" correlations and their temporal evolutions between winter-time PNA/EPW and winter drought in the west United States.
abstract: In this study, relations between winter-time Pacific-Northern America pattern (PNA)/East Pacific wave-train (EPW) and winter-time drought in the west United States over the period of 1951-2010 are analyzed. Considering traditional Pearson's Correlation Coefficient can be influenced by non-stationarity and nonlinearity, a recently proposed method, Detrended Partial-Cross-Correlation Analysis (DPCCA) is applied. With DPCCA, we analyzed the "intrinsic" correlations between PNA/EPW and the winter drought with possible effects of ENSO and PDO removed. We found, i) significant negative correlations between PNA/EPW and drought on time scales of 5-6 years after removing the effects of ENSO, ii) and significant negative correlations between PNA/EPW and drought on time scales of 15-25 years after removing the effects of PDO. By further studying the temporal evolutions of the "intrinsic" correlations, we found on time scales of 5-6 years, the "intrinsic" correlations between PNA/EPW and drought can vary severely with time, but for most time, the correlations are negative. While on interdecadal (15-25 years) time scales, after the effects of PDO removed, unlike the relations between PNA and drought, the "intrinsic" correlations between EPW and drought takes nearly homogeneous-sign over the whole period, indicating a better model can be designed by using EPW.
authors.affiliation: Lab for Climate and Ocean-Atmosphere Studies, Dept. of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Piao
authors.affiliation: Lab for Climate and Ocean-Atmosphere Studies, Dept. of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China.
authors.forename: Zuntao
authors.initials: Z
authors.lastname: Fu
authors.affiliation: Lab for Climate and Ocean-Atmosphere Studies, Dept. of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871, China.|Chinese Academy of Meteorological Science, Beijing, 100081, China.
authors.forename: Naiming
authors.initials: N
authors.lastname: Yuan
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