Evaluation of three new surface irrigation parameterizations in the WRF-ARW v3.8.1 model: the Po Valley (Italy) case study
<p>Irrigation is a method of land management that can affect the local climate. Recent literature shows that it affects mostly the near-surface variables and it is associated with an irrigation cooling effect. However, there is no common parameterization that also accounts for a realistic wate...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-07-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/13/3179/2020/gmd-13-3179-2020.pdf |
| Summary: | <p>Irrigation is a method of land management that can affect the local climate. Recent literature
shows that it affects mostly the near-surface variables and it is associated with an irrigation
cooling effect. However, there is no common parameterization that also accounts for a realistic
water amount, and this factor could ascribe one cause to the different impacts found in previous
studies. This work aims to introduce three new surface irrigation parameterizations within the
WRF-ARW model (v3.8.1) that consider different evaporative processes. The parameterizations are
tested on one of the regions where global studies disagree on the signal of irrigation: the
Mediterranean area and in particular the Po Valley. Three sets of experiments are performed using
the same irrigation water amount of 5.7 <span class="inline-formula">mm d<sup>−1</sup></span>, derived from Eurostat data. Two complementary
validations are performed for July 2015: monthly mean, minimum, and maximum temperature with ground
stations and potential evapotranspiration with the MODIS product. All tests show that for both
mean and maximum temperature, as well as potential evapotranspiration simulated fields
approximate observation-based values better when using the irrigation parameterizations. This
study addresses the sensitivity of the results to human-decision
assumptions of the parameterizations: start time, length, and frequency. The main impact of irrigation on surface variables
such as soil moisture is due to the parameterization choice itself affecting evaporation, rather
than the timing. Moreover, on average, the atmosphere and soil variables are not very sensitive to
the parameterization assumptions for realistic timing and length.</p> |
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| ISSN: | 1991-959X 1991-9603 |