How do atmosphere models reproduce observed extreme precipitation events?.

Kanzler, Leah (2022) How do atmosphere models reproduce observed extreme precipitation events?. (Bachelor thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 30 pp.

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The importance of warning the population of floods and extreme precipitation is big and therefore the related importance of precise extreme weather forecast. To investigate the reproduction of extreme precipitation events in atmospheric models we compared the daily precipitation simulated by the Integrated Forecasting System (IFS) Cycle 36r4 to the Observation data from the Global Precipitation Climatology Project (GPCP) Climate Data Record (CDR) daily analysis. A key part of the study is to analyse the model bias and uncertainty of simulated extreme precipitation. We consider different horizontal resolutions for the model data and additionally compare them with each other. The GPCP data is given in a 1° × 1° grid while the model data has a horizontal resolution of 100 km for the low-resolution model (OIFS-LR) and 50 km for the high-resolution model (OIFS-HR). The focus of the comparison lies on the time period from the 1st of January 1997 to the 31st of December 2019. As a threshold for extreme precipitation events, we define 60 mm per 24 hours. We use seasonal means to analyse the differences of reproducing averaged precipitation to then look at the frequency of occurrence of extreme precipitation events. Especially in the low-resolution model deficiencies over steep topography were observed in the time mean. The high-resolution model represents the seasonal mean of precipitation reasonably well. The OIFS-HR represents a higher frequency of heavy rainfalls than the OIFS-LR. It can be assumed that the high-resolution model represents storm tracks and tropical cyclones better than the OIFS-LR.

Document Type: Thesis (Bachelor thesis)
Thesis Advisor: Kjellsson, Joakim and Huo, Wenjuan
Keywords: weather prediction; Integrated Forecasting System (IFS); Global Precipitation Climatology Project (GPCP)
Subjects: Course of study: BSc Physics of the Earth System
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Date Deposited: 02 Aug 2022 10:02
Last Modified: 02 Aug 2022 10:55

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