Assimilating monthly precipitation data in a paleoclimate data assimilation framework

Valler, Veronika; Brugnara, Yuri; Franke, Jörg; Brönnimann, Stefan (2020). Assimilating monthly precipitation data in a paleoclimate data assimilation framework (In Press). Climate of the past Copernicus Publications 10.5194/cp-2019-137

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Data assimilation approaches such as the ensemble Kalman filter method have become an important technique for paleoclimatological reconstructions and reanalysis. Different sources of information from proxy records and documentary data to instrumental measurements were assimilated in previous studies to reconstruct past climate fields. However, precipitation reconstructions are often based on indirect sources (e.g., proxy records). Assimilating precipitation measurements is a challenging task because they have high uncertainties, often represent only a small region and generally do not follow Gaussian distribution. In this paper, a set of experiments are conducted to test the possibility of using information about precipitation in climate reconstruction with monthly resolution by assimilating monthly instrumental precipitation amounts or the number of wet days per month, solely or in addition to other climate variables such as temperature and sea level pressure, into an ensemble of climate model simulations. The skill of all variables (temperature, precipitation, sea-level pressure) improved over the pure model simulations when only monthly precipitation amounts were assimilated. Assimilating the number of wet days resulted in similar or better skill compared to assimilating precipitation amount. The experiments with different types of instrumental observations being assimilated indicate that precipitation data can be useful, particularly if no other variable is available from a given region. Overall the experiments show promising results because with the assimilation of precipitation information a new data source can be exploited for climate reconstructions. Especially the wet day records can become an important data source in future climate reconstructions because many existing records date several centuries back in time and are not limited by the availability of meteorological instruments.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Climatology
08 Faculty of Science > Institute of Geography

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Valler, Veronika; Brugnara, Yuri; Franke, Jörg and Brönnimann, Stefan

Subjects:

900 History > 910 Geography & travel

ISSN:

1814-9324

Publisher:

Copernicus Publications

Funders:

[4] Swiss National Science Foundation
[UNSPECIFIED] European Commission - Horizon 2020

Language:

English

Submitter:

André Hürzeler

Date Deposited:

26 Jun 2020 10:23

Last Modified:

26 Jun 2020 10:23

Publisher DOI:

10.5194/cp-2019-137

Related URLs:

Additional Information:

Climate of the past discussions

BORIS DOI:

10.7892/boris.144867

URI:

https://boris.unibe.ch/id/eprint/144867

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