 |
| Titel |
Impact of long-term climate histories on estimated ground warming patterns: A spatial analysis over North America |
| VerfasserIn |
Gurpreet S. Matharoo, Hugo Beltrami, Lev Tarasov, Volker Rath, Jason E. Smerdon |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077593
|
|
|
|
|
|
| Zusammenfassung |
| Climate reconstructions from borehole temperature profiles are important independent
estimates of past temperature variability over the last millennium. There remain, however,
uncertainties in the interpretation of these data as climatic indicators as well as in the
evaluation of heat gain/loss by the terrestrial land masses. One of these uncertainties is
associated with the often unaccounted for impact of the Last Glacial Maximum (LGM) on
the estimate of the background steady-state signal associated with the diffusion of
accretionary energy from the Earth’s interior. Here we use basal temperature values from
the data-calibrated Glacial Systems Model (GSM) to quantify the extent of the
perturbation to estimated steady-state temperature profiles and derive spatial maps of the
expected impacts on estimated profiles over North America. Furthermore, we present
quantitative estimates of the potential effects of LGM temperature changes on the
borehole reconstructions over the last millennium for North America. The range of
these possible impacts are estimated using basal temperatures generated from the
GSM for a period covering 120 kyrs to the present day and a 1000-member Monte
Carlo experiment at each location in which Gaussian noise is added to the basal
temperature history from the GSM. For all the locations, we find the LGM induced
perturbation to the steady-state temperature profile to be constant on the order of
10Â mWÂ m-2 within the depth ranges that are typical for available boreholes (~ 600m) and
reduce with greater depths. As a result of LGM induced perturbations, most of the
locations show heat gain within the top 80Â m in the subsurface and heat loss beyond
80Â m. Furthermore as a result of these perturbations, most of the locations show
an average temperature increase of 0.5o over the last 500 years before present. |
|
|
|
|
|
|