Precipitation observations and simulations during the LIAISE-2021 field campaign

Within the framework of the GEWEX initiative  “Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment” (LIAISE), the WISE-PreP project was carried out to study precipitation processes aiming to characterize possible differences in precipitation induced by surface characteristics (irrigated vs non-irrigated areas) in NE Spain. Specific deployed instrumentation during the 2021 campaign included three sites equipped each with a vertical radar Doppler Micro Rain Radar (MRR) and a laser disdrometer (PARSIVEL), plus an additional PARSIVEL disdrometer, covering both irrigated and non-irrigated sites. Time series of vertical precipitation profiles and in-situ drop size distributions were recorded to study microphysical processes and related variables including precipitation intensity or convective vs stratiform rainfall regimes.

First results show higher accumulated precipitation in the non-irrigated area (eastern area) than those in irrigated area (western area) in summer 2021, a feature also observed in summers for a previous reference period (2010-2019). Maximum and minimum daily temperatures were higher in irrigated areas than in non-irrigated areas. Both results are consistent with current climatology based on monthly precipitation and temperature that indicate the existence of a zonal gradient that increases semi-arid conditions (drier and warmer) from the east to the west. Disdrometer derived 1-min rainfall rate distributions presented some differences between the irrigated and non-irrigated areas during summer, unlike the other seasons when surface conditions are more similar in both areas. An overview of additional results obtained with numerical simulations using the WRF model is also provided. This research was supported by projects WISE-PreP (RTI2018-098693-B-C32) and ARTEMIS (PID2021-124253OB-I00) and the Water Research Institute (IdRA) of the University of Barcelona.