Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy

Abstract Reanalyses are utilized for calculating climatological trends due to their focus on temporal consistency. ERA5 reanalysis family has proven to be a valuable and widely used product for trend extraction. This study specifically examines long‐term trends in total annual precipitation across t...

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Main Authors: Cristian Lussana, Francesco Cavalleri, Michele Brunetti, Veronica Manara, Maurizio Maugeri
Format: Article
Language:English
Published: Wiley 2024-09-01
Series:Atmospheric Science Letters
Subjects:
Online Access:https://doi.org/10.1002/asl.1239
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author Cristian Lussana
Francesco Cavalleri
Michele Brunetti
Veronica Manara
Maurizio Maugeri
author_facet Cristian Lussana
Francesco Cavalleri
Michele Brunetti
Veronica Manara
Maurizio Maugeri
author_sort Cristian Lussana
collection DOAJ
description Abstract Reanalyses are utilized for calculating climatological trends due to their focus on temporal consistency. ERA5 reanalysis family has proven to be a valuable and widely used product for trend extraction. This study specifically examines long‐term trends in total annual precipitation across two climatic hotspots: the Alps and Italy. It is acknowledged by reanalysis producers that variations in the observational systems used for data assimilation impact water cycle components like precipitation. This understanding highlights the need of assessing to what extent temporal variations in ERA5 precipitation amounts are solely a result of climate variations and the influence of changes in the observational system impacting simulation accuracy. Our research examines the differences between ERA5 and similar reanalyses against homogenized, trend‐focused observational datasets. We find that discerning the climatological signal within ERA5 adjustments for observational system variations is challenging. The trend in ERA5 from 1940 to 1970 shows distinct patterns over the Alps and, to a lesser extent, Italy, diverging from later ERA5 trends and those in other reanalyses. Notably, ERA5 shows an increasing, although nonlinear, trend in the deviation between ERA5 and the observational datasets. Improving future reanalysis interpretability could involve adopting a model‐only integration for the same period, akin to the ERA‐20C and ERA‐20CM approach.
format Article
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institution OA Journals
issn 1530-261X
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publishDate 2024-09-01
publisher Wiley
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series Atmospheric Science Letters
spelling doaj-art-cb4f956174414feb8a4479448c00dbc32025-08-20T02:34:44ZengWileyAtmospheric Science Letters1530-261X2024-09-01259n/an/a10.1002/asl.1239Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and ItalyCristian Lussana0Francesco Cavalleri1Michele Brunetti2Veronica Manara3Maurizio Maugeri4Division for Climate Services The Norwegian Meteorological Institute Oslo NorwayEnvironmental Science and Policy Department University of Milan Milan ItalyInstitute of Atmospheric Sciences and Climate National Research Council (CNR‐ISAC) Bologna ItalyEnvironmental Science and Policy Department University of Milan Milan ItalyEnvironmental Science and Policy Department University of Milan Milan ItalyAbstract Reanalyses are utilized for calculating climatological trends due to their focus on temporal consistency. ERA5 reanalysis family has proven to be a valuable and widely used product for trend extraction. This study specifically examines long‐term trends in total annual precipitation across two climatic hotspots: the Alps and Italy. It is acknowledged by reanalysis producers that variations in the observational systems used for data assimilation impact water cycle components like precipitation. This understanding highlights the need of assessing to what extent temporal variations in ERA5 precipitation amounts are solely a result of climate variations and the influence of changes in the observational system impacting simulation accuracy. Our research examines the differences between ERA5 and similar reanalyses against homogenized, trend‐focused observational datasets. We find that discerning the climatological signal within ERA5 adjustments for observational system variations is challenging. The trend in ERA5 from 1940 to 1970 shows distinct patterns over the Alps and, to a lesser extent, Italy, diverging from later ERA5 trends and those in other reanalyses. Notably, ERA5 shows an increasing, although nonlinear, trend in the deviation between ERA5 and the observational datasets. Improving future reanalysis interpretability could involve adopting a model‐only integration for the same period, akin to the ERA‐20C and ERA‐20CM approach.https://doi.org/10.1002/asl.1239annual precipitationclimatological trendsERA5Greater Alpine regionItalyLAPREC
spellingShingle Cristian Lussana
Francesco Cavalleri
Michele Brunetti
Veronica Manara
Maurizio Maugeri
Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
Atmospheric Science Letters
annual precipitation
climatological trends
ERA5
Greater Alpine region
Italy
LAPREC
title Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
title_full Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
title_fullStr Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
title_full_unstemmed Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
title_short Evaluating long‐term trends in annual precipitation: A temporal consistency analysis of ERA5 data in the Alps and Italy
title_sort evaluating long term trends in annual precipitation a temporal consistency analysis of era5 data in the alps and italy
topic annual precipitation
climatological trends
ERA5
Greater Alpine region
Italy
LAPREC
url https://doi.org/10.1002/asl.1239
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AT michelebrunetti evaluatinglongtermtrendsinannualprecipitationatemporalconsistencyanalysisofera5datainthealpsanditaly
AT veronicamanara evaluatinglongtermtrendsinannualprecipitationatemporalconsistencyanalysisofera5datainthealpsanditaly
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