Contrasting stable water isotope signals from convective and large-scale precipitation phases of a heavy precipitation event in southern Italy during HyMeX IOP 13: a modelling perspective
The dynamical context and moisture transport pathways embedded in large-scale flow and associated with a heavy precipitation event (HPE) in southern Italy (SI) are investigated with the help of stable water isotopes (SWIs) based on a purely numerical framework. The event occurred during the Intensiv...
| Published in: | Atmospheric Chemistry and Physics |
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| Main Authors: | , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus Publications
2019
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/acp-19-7487-2019 https://doaj.org/article/cac8bb4a285b454da4950276ccd9cfb0 |
| Summary: | The dynamical context and moisture transport pathways embedded in large-scale flow and associated with a heavy precipitation event (HPE) in southern Italy (SI) are investigated with the help of stable water isotopes (SWIs) based on a purely numerical framework. The event occurred during the Intensive Observation Period (IOP) 13 of the field campaign of the Hydrological Cycle in the Mediterranean Experiment (HyMeX) on 15 and 16 October 2012, and SI experienced intense rainfall of 62.4 mm over 27 h with two precipitation phases during this event. The first one (P1) was induced by convective precipitation ahead of a cold front, while the second one (P2) was mainly associated with precipitation induced by large-scale uplift. The moisture transport and processes responsible for the HPE are analysed using a simulation with the isotope-enabled regional numerical model COSMO iso . The simulation at a horizontal grid spacing of about 7 km over a large domain (about 4300 km ×3500 km) allows the isotopes signal to be distinguished due to local processes or large-scale advection. Backward trajectory analyses based on this simulation show that the air parcels arriving in SI during P1 originate from the North Atlantic and descend within an upper-level trough over the north-western Mediterranean. The descending air parcels reach elevations below 1 km over the sea and bring dry and isotopically depleted air (median δ 18 O <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≤</mo><mo>-</mo><mn mathvariant="normal">25</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="db1890df7e308eaa6b2e59d6a2629782"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-7487-2019-ie00001.svg" width="32pt" height="11pt" src="acp-19-7487-2019-ie00001.png"/></svg:svg> ‰, water vapour mixing ratio q ... |
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