Isotopic composition of the precipitations in the central Mediterranean: Origin marks and orographic precipitation effects

Mariano Valenza, Rocco Favara, Marcello Liotta

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Abstract

The isotopic composition of the rainfall in northwestern Sicily (Italy, central Mediterranean) was investigated in the period February 2002 to March 2003. A rain gauge network was installed and sampled monthly. The monthly values of the D and 18O ratios showed a wide range that reflected seasonal climatic variations. Mean weighted values were used to define an isotopic model of precipitation. Temporal variations in deuterium excess were also investigated. Using mean volume weighted values, the Local Meteoric Water Line (LMWL) can be represented by the equation: δD = 4.7δ18O - 8.2 (r2 = 0.96). Deuterium excess (d = δD - 8δ18O) was found to be strongly related to orography. The coastline samples were characterized by mean weighted deuterium excess values close to 12.5‰ samples from inland areas showed values of 169‰, while samples taken from the main reliefs showed values close to 19%· In inland areas, isotopic exchange between raindrops and moisture could shift the deuterium excess values slightly. On the higher reliefs, the interaction between falling raindrops and orographic clouds could shift the deuterium excess values significantly. The low slope of the LMWL could be referred to the high deuterium excess values of the higher sites and is related to orographic precipitation rather than to evaporation processes during the fall of the raindrops. The results obtained suggest that local orographic features may significantly change the isotopic composition of precipitation. Copyright 2006 by the American Geophysical Union.
Lingua originaleEnglish
pagine (da-a)D019302-D019314
Numero di pagine13
RivistaJOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH
Volume111
Stato di pubblicazionePublished - 2006

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Palaeontology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Earth-Surface Processes
  • Geochemistry and Petrology
  • Soil Science
  • Water Science and Technology
  • Ecology
  • Aquatic Science
  • Oceanography
  • Forestry

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title = "Isotopic composition of the precipitations in the central Mediterranean: Origin marks and orographic precipitation effects",
abstract = "The isotopic composition of the rainfall in northwestern Sicily (Italy, central Mediterranean) was investigated in the period February 2002 to March 2003. A rain gauge network was installed and sampled monthly. The monthly values of the D and 18O ratios showed a wide range that reflected seasonal climatic variations. Mean weighted values were used to define an isotopic model of precipitation. Temporal variations in deuterium excess were also investigated. Using mean volume weighted values, the Local Meteoric Water Line (LMWL) can be represented by the equation: δD = 4.7δ18O - 8.2 (r2 = 0.96). Deuterium excess (d = δD - 8δ18O) was found to be strongly related to orography. The coastline samples were characterized by mean weighted deuterium excess values close to 12.5‰ samples from inland areas showed values of 169‰, while samples taken from the main reliefs showed values close to 19{\%}· In inland areas, isotopic exchange between raindrops and moisture could shift the deuterium excess values slightly. On the higher reliefs, the interaction between falling raindrops and orographic clouds could shift the deuterium excess values significantly. The low slope of the LMWL could be referred to the high deuterium excess values of the higher sites and is related to orographic precipitation rather than to evaporation processes during the fall of the raindrops. The results obtained suggest that local orographic features may significantly change the isotopic composition of precipitation. Copyright 2006 by the American Geophysical Union.",
author = "Mariano Valenza and Rocco Favara and Marcello Liotta",
year = "2006",
language = "English",
volume = "111",
pages = "D019302--D019314",
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}

TY - JOUR

T1 - Isotopic composition of the precipitations in the central Mediterranean: Origin marks and orographic precipitation effects

AU - Valenza, Mariano

AU - Favara, Rocco

AU - Liotta, Marcello

PY - 2006

Y1 - 2006

N2 - The isotopic composition of the rainfall in northwestern Sicily (Italy, central Mediterranean) was investigated in the period February 2002 to March 2003. A rain gauge network was installed and sampled monthly. The monthly values of the D and 18O ratios showed a wide range that reflected seasonal climatic variations. Mean weighted values were used to define an isotopic model of precipitation. Temporal variations in deuterium excess were also investigated. Using mean volume weighted values, the Local Meteoric Water Line (LMWL) can be represented by the equation: δD = 4.7δ18O - 8.2 (r2 = 0.96). Deuterium excess (d = δD - 8δ18O) was found to be strongly related to orography. The coastline samples were characterized by mean weighted deuterium excess values close to 12.5‰ samples from inland areas showed values of 169‰, while samples taken from the main reliefs showed values close to 19%· In inland areas, isotopic exchange between raindrops and moisture could shift the deuterium excess values slightly. On the higher reliefs, the interaction between falling raindrops and orographic clouds could shift the deuterium excess values significantly. The low slope of the LMWL could be referred to the high deuterium excess values of the higher sites and is related to orographic precipitation rather than to evaporation processes during the fall of the raindrops. The results obtained suggest that local orographic features may significantly change the isotopic composition of precipitation. Copyright 2006 by the American Geophysical Union.

AB - The isotopic composition of the rainfall in northwestern Sicily (Italy, central Mediterranean) was investigated in the period February 2002 to March 2003. A rain gauge network was installed and sampled monthly. The monthly values of the D and 18O ratios showed a wide range that reflected seasonal climatic variations. Mean weighted values were used to define an isotopic model of precipitation. Temporal variations in deuterium excess were also investigated. Using mean volume weighted values, the Local Meteoric Water Line (LMWL) can be represented by the equation: δD = 4.7δ18O - 8.2 (r2 = 0.96). Deuterium excess (d = δD - 8δ18O) was found to be strongly related to orography. The coastline samples were characterized by mean weighted deuterium excess values close to 12.5‰ samples from inland areas showed values of 169‰, while samples taken from the main reliefs showed values close to 19%· In inland areas, isotopic exchange between raindrops and moisture could shift the deuterium excess values slightly. On the higher reliefs, the interaction between falling raindrops and orographic clouds could shift the deuterium excess values significantly. The low slope of the LMWL could be referred to the high deuterium excess values of the higher sites and is related to orographic precipitation rather than to evaporation processes during the fall of the raindrops. The results obtained suggest that local orographic features may significantly change the isotopic composition of precipitation. Copyright 2006 by the American Geophysical Union.

UR - http://hdl.handle.net/10447/19728

UR - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JD006818

M3 - Article

VL - 111

SP - D019302-D019314

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 2169-9313

ER -