Abstract:
Kathmandu tree-ring based temperature reconstructions and
instrumental weather data. Reconstructions for pre-monsoon (February-June)
and post-monsoon (October-February) seasons, for the periods 1546-1991 AD
and 1605-1991 AD, respectively.
ABSTRACT (from the online documentation):
We describe the development of a tree-ring chronology network in Nepal that is
suitable for reconstructing
... temperature-related climate forcing over the past
few hundred years. The network is composed of 32 tree-ring chronologies and is
represented by five indigenous tree species. An empirical orthogonal function
analysis of the chronologies over the common interval 1796-92 indicates the
existence of coherent large-scale signals among the tree-ring chronologies
that are hypothesized to reflect, in part, broad-scale climate forcing related
to temperatures. A long monthly temperature record for Kathmandu is developed
and used to test this hypothesis. In so doing, significant monthly and
seasonal temperature responses are identified that provide guidance for the
formal reconstruction of two temperature seasons: February-June (1546-91) and
October-February (1605-91). Each reconstruction indicates the occurrence of
unusually cold temperatures in 1815-22, which coincides with the eruption of
Tambora in Indonesia. A novel method is also used to add probable missing
multi-centennial temperature variance to each reconstruction. The resulting
adjusted reconstructions strongly reflect patterns of temperature variability
associated with Little Ice Age cooling and warming into the 20th century, with
the October-February season exhibiting the strongest increase in temperature
over the past 400 years. Only the October-February season shows any evidence
for late- 20th century warming, whereas February-June temperatures have
actually cooled since 1960 (as with the observational series). 
