 |
| Titel |
Changes in surface solar radiation in Northeastern Spain over the past six centuries recorded by tree-ring δ13C |
| VerfasserIn |
Isabel Dorado Liñán, Arturo Sanchez-Lorenzo, Emilia Gutiérrez Merino, Octavi Planells, Ingo Heinrich, Gerhard Helle, Eduardo Zorita |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111589
|
| Publikation (Nr.) |
 EGU/EGU2015-11723.pdf |
|
|
|
|
|
| Zusammenfassung |
| Stable carbon isotopes in tree rings (δ13C) are assumed to be well established proxy
indicators of past variations of temperature and hydroclimate variables. The discrimination of
13C in the organic matter (i.e. tree rings) reflects the balance between the leaf photosynthetic
rate and the stomatal conductance to CO2 [Farquhar et al., 1982] which are strongly
dependent on environmental variables such as temperature, humidity, and solar
radiation. The control exerted by solar radiation on the physiological processes
underlining carbon discrimination in tree rings suggests the large potential of this
palaeoproxy in estimations of past changes of light availability. Based on that theory, some
studies have successfully achieved the reconstructions of cloud cover and sunshine
duration based on δ13C variations on tree-rings [i.e. Gagen et al., 2011; Loader et
al., 2013]. However, the largely inter-dependence of the climate factors governing
plant physiological processes hampers the unequivocal identification of the most
limiting driver of isotope discrimination in a given region (e.g., surface solar radiation
signals can be easily misinterpret as temperature signals). Similarly, surface solar
radiation, sunshine duration and percentage of cloud cover largely covary but the short
instrumental series hinder the detection of the non-linearities and thus the identification of
the main driver of plant growth. We present a detailed study in northeast Spain in
which the use of several station data and the effect of the volcanic eruptions on both
instrumental and tree-ring data revealed surface solar radiation as the main driver of
13C discrimination in tree rings. Based on that relationship, we develop a surface
solar radiation reconstruction in northeast Spain that covers the last 600 years. The
relationship between past temperature and past SSR at this site is complex, with
no clear linear relationship that could be used to infer the sign of a cloud cover
feedback. Our results show the potential of using volcanic eruptions to discern the main
driver of 13C discrimination and the need to extend the geographical coverage of
δ13C chronologies to better understand the interaction between past temperatures
and SSR on continental scales, a key parameter contributing to the overall climate
sensitivity.
References
Farquhar, G. D., M. H. O’Leary, and J. A. Berry (1982), On the relationship between carbon
isotope discrimination and intercellular carbon dioxide concentration in leaves, Austral. J.
Plant Physiol., 9, 121–137.
Gagen, M., E. Zorita, D. McCarroll, G. H. F. Young, H. Grudd, R. Jalkanen, N. J. Loader, I.
Robertson and A. J. Kirchhefer (2011), Cloud response to summer temperatures in
Fennoscandia over the last thousand years, Geophys. Res. Lett., 38, L05701, doi:
10.1029/2010GL046216.
Loader, N. J., G. H. F. Young, H. Grudd, and D. McCarroll (2013), Stable carbon isotopes
from Torneträsk, northern Sweden provide a millennial length reconstruction of
summer sunshine and its relationship to Arctic circulation, Quaternary Sci. Rev., 62,
97–113. |
|
|
|
|
|
|