Environmental Engineering Reference
In-Depth Information
Chapter 7
Developing a Historical Precipitation Record
Thomas M. Smith
Abstract Knowing historical precipitation is important for climate monitoring and
for evaluating coupled climate models designed to simulate changes in precipitation
associated with climate change. Over land gauge-based analyses are sufficient to
determine large-scale variations over the twentieth century. Over oceans satellite-
based analyses can be used beginning 1979. However, there are few direct or remote
sensing observations of oceanic precipitation variations before 1979. For the pre-
satellite time, it is possible to use reconstructions based on the available data to
analyze some oceanic precipitation variations. Evaluations of the available data and
methods have shown that large-scale variations in twentieth-century oceanic precipi-
tation may be reconstructed. Reconstructions based on spatial covariance and histor-
ical gauge data represent seasonal to interannual variations. Reconstructions based on
correlations with sea-surface temperature (SST) and sea-level pressure (SLP) repre-
sent multi-decadal variations. Combining these two types of reconstructions yields a
merged reconstruction with the best features of both.
This review describes how the reconstructions are developed and discusses their
major features. The merged reconstruction indicates increasing precipitation with
increasing global temperature, consistent with theoretical estimates. However, the
reconstruction indicates that the change is not steady and has a shift associated with
the climate shift noted in Pacific SSTs in the 1970s.
Keywords Climate • Precipitation • Reconstruction
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