 |
| Titel |
Tree-ring latewood width based July–August SPEI reconstruction in South China since AD 1888 and its possible connection with ENSO |
| VerfasserIn |
Yesi Zhao, Jiangfeng Shi, Shiyuan Shi, Jian Yu, Huayu Lu |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250147238
|
| Publikation (Nr.) |
 EGU/EGU2017-11367.pdf |
|
|
|
|
|
| Zusammenfassung |
| Our understanding of the long-term hydroclimate variations in South China is prohibited by
the shortness of meteorological records. Paleoclimatic proxies, such as tree-rings,
can be pursued to extend the meteorological records back for centuries to help
us better understand hydroclimatic conditions. In this study, we reconstructed the
July–August Standardized Precipitation–Evapotranspiration Index (SPEIJul−Aug) based
on a newly developed 127-year adjusted latewood width chronology from Tsuga
longibracteata, South China. In specific, the latewood width chronology was regressed on the
earlywood width chronology using a simple linear regression, and the residuals plus a
constant 1.0 were defined as the adjusted latewood width chronology. The chronology
explained 40% of the actual SPEIJul−Aug variance in the period 1953–2014. The
reconstructed SPEIJul−Aug can represent large-scale July–August SPEI variations
over South China, including northern Guangxi, Hunan, and Guizhou provinces.
From the perspective of the past 127 years, the extreme summer drought in 2013
was not unusual because more extreme drought events occurred in the first half
of the 20th century. A significant 2.0–3.6-year hydroclimatic cycle existed in the
reconstruction, which indicated that the SPEIJul−Aug might be driven by El Niño–Southern
Oscillation (ENSO). We further checked the time-dependency of the relationship
between SPEIJul−Augand ENSO and found that it was unstable. Their relationship
was weak before the 1950s, became significant from the 1950s to early 1990s, and
then dropped to be weak again and even out of phase since the early 1990s, which
may be attributable to the significant westward extension of the western Pacific
subtropical high. This study indicates that summer hydroclimate in South China can be
reconstructed based on adjusted latewood width, and will be better understood when more
and longer adjusted latewood width chronologies are obtained in the near future. |
|
|
|
|
|
|