Effects of record length and resolution on the derived distribution of annual precipitation
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Date
2015-12-15Type
- Working Paper
ETH Bibliography
yes
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Abstract
Traditional frequency analysis of annual precipitation requires the fitting of a proba-bility model to yearly precipitation totals. There are three potential problems with thisapproach: a long record (at least 25∼30 years) is required in order to fit the model,years with missing data cannot be used, and the data need to be homogeneous. To overcome these limitations, we test an alternative methodology proposed by Eagleson(1978), based on the derived distribution approach (DDA). This allows for better estimation of the probability density function (pdf) of annual rainfall without requiring longrecords, provided that high-resolution precipitation data are available to derive external storm properties. The DDA combines marginal pdfs for storm depth and inter-arrival time to arrive at an analytical formulation of the distribution of annual precipitation underthe assumption of independence between events. We tested the DDA at two temperate locations in different climates (Concepción, Chile, and Lugano, Switzerland), quantify-ing the effects of record length. Our results show that, as compared to the fitting of anormal or log-normal distribution, the DDA significantly reduces the uncertainty in annual precipitation estimates (especially interannual variability) when only short recordsare available. The DDA also reduces the bias in annual precipitation quantiles withhigh return periods. We also show that using precipitation data aggregated every 24 h,as commonly available at most weather stations, introduces a noticeable bias in the DDA. Our results point to the tangible benefits of installing high-resolution (hourly or less) precipitation gauges at previously ungauged locations. We show that the DDA,in combination with high resolution gauging, provides more accurate and less uncertain estimates of long-term precipitation statistics such as interannual variability andquantiles of annual precipitation with high return periods even for records as short as 5 years. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000108583Publication status
publishedExternal links
Journal / series
Hydrology and Earth System Sciences DiscussionsVolume
Pages / Article No.
Publisher
CopernicusOrganisational unit
03473 - Burlando, Paolo / Burlando, Paolo
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Is previous version of: https://doi.org/10.3929/ethz-b-000236736
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