 |
| Titel |
Variations in air and ground temperature and the POM-SAT model: results from the Northern Hemisphere |
| VerfasserIn |
R. N. Harris |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 3, no. 4 ; Nr. 3, no. 4 (2007-10-09), S.611-621 |
| Datensatznummer |
250001176
|
| Publikation (Nr.) |
 copernicus.org/cp-3-611-2007.pdf |
|
|
|
|
|
| Zusammenfassung |
| The POM-SAT model for comparing air and ground temperatures is based on the
supposition that surface air temperature (SAT) records provide a good
prediction of thermal transients in the shallow subsurface of the Earth.
This model consists of two components, the forcing function and an initial
condition, termed the pre-observational mean (POM). I explore the
sensitivity of this model as a function of forcing periods at time scales
appropriate for climate reconstructions. Synthetic models are designed to
replicate comparisons between borehole temperatures contained in the global
database of temperature profiles for climate reconstructions and gridded SAT
data. I find that the root mean square (RMS) misfit between forcing
functions and transient temperature profiles in the subsurface are sensitive
to periods longer than about 50 years, are a maximum when the period and the
150-year time series are equal and then decreases for longer periods. The
magnitude of the POM is a robust parameter for periods equal to or shorter
than the length of this time series. At longer periods there is a tradeoff
between the amplitude of the forcing function and the POM. These tests
provide guidelines for assessing comparisons between air and ground
temperatures at periods appropriate for climate reconstructions. The
sensitivity of comparisons between the average Northern Hemisphere gridded
SAT record and subsurface temperature-depth profile as a function of forcing
period is assessed. This analysis indicates that the Northern Hemisphere
extratropical average SAT and reduced temperature-depth profile are in good
agreement. By adding modest heat to the subsurface at intermediate periods
some improvement in misfit can be made, but this extra heat has negligible
influence on the POM. The joint analysis of borehole temperatures and SAT
records indicate warming of about 1.1°C over the last 500 years,
consistent with previous studies. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|