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VERSION:2.0
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BEGIN:VEVENT
DTSTAMP:20260626T051406Z
UID:https://www.mpgc-mainz.de/events/32587/2368
DTSTART;VALUE=DATE:20230111
DTEND;VALUE=DATE:20230112
CLASS:PUBLIC
CREATED:20221018T120928Z
DESCRIPTION:Speleothem d18O values depend on a complex interplay of various
  processes occurring in the atmosphere\, the soil and karst above the cave
  as well as during precipitation of speleothem calcite. Thus\, the relatio
 nship between speleothem d18O values and climate parameters\, such as loca
 l and supra-regional temperature and precipitation patterns\, is in many c
 ases not straightforward. Here we present a set of global simulations for 
 different time periods (Modern Day\, LGM\, MIS3\, …) with a mean duratio
 n of 20 years\, performed with the EMAC atmospheric chemistry general circ
 ulation model\, being enhanced with stable water isotope diagnostics. The 
 model resolution comprises of a horizontal grid with a maximum resolution 
 of 0.88° × 0.88° (T106) and a vertical resolution of 31 model levels (t
 op level at 0.01 hPa). The simulated d18O values in precipitation were con
 verted into synthetic speleothem d18O records by accounting for the effect
 s of evapotranspiration and infiltration using model-internal empirical ev
 apotranspiration submodels as well as the drip&amp\;#2\;water-to-calcite f
 ractionation equation by Tremaine et al. (2011). We then calculated mean s
 peleothem d18O values on an annual and seasonal basis\, weighted by the am
 ount of precipitation and infiltration (pw-d 18O\, iw-d 18O)\, respectivel
 y. The synthetic speleothem d18O records were compared with speleothem d18
 O records from the Speleothem Isotopes Synthesis and Analysis Working grou
 p (SISAL) database. In general\, the model setup is capable of adequately 
 simulating the global pattern of d18O values in precipitation. The synthet
 ic speleothem d18O records clearly benefit from weighting by the amount of
  precipitation and\, partly\, even more from weighting by infiltration (i.
 e.\, the application of an evapotranspiration model). This is obvious by t
 he better agreement of iw-d18O speleothem records with the SISAL data for 
 regions with an infiltration-to-precipitation ratio &lt\;0.7 (e.g.\, the M
 editerranean Region). In temperate regions\, such as Central Europe\, the 
 iw-d18O is approximately similar to the corresponding pw-d18O. Thus\, infi
 ltration in these regions seem to be less influenced by evapotranspiration
  and surface runoff. The evapotranspiration model but limitations when cal
 culating evapotranspiration in extremely arid and/or cold areas\, possibly
  resulting in biased iw-d18O values. Commonly\, the climate of these regio
 ns is too harsh for speleothem growth\, and therefore currently not subjec
 t of this study.\nSpeaker: Tim Liesenhoff
LAST-MODIFIED:20221020T081043Z
LOCATION:
SUMMARY:Quantitative climate modeling based on multi-proxy data of precisel
 y dated speleothems
URL;VALUE=URI:https://www.mpgc-mainz.de/events/32587/2368
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