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| Titel |
Gridded sunshine duration climate data record for Germany based on combined satellite and in situ observations |
| VerfasserIn |
Jakub Walawender, Steffen Kothe, Jörg Trentmann, Uwe Pfeifroth, Roswitha Cremer |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148019
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| Publikation (Nr.) |
 EGU/EGU2017-12244.pdf |
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| Zusammenfassung |
| The purpose of this study is to create a 1 km2 gridded daily sunshine duration data record for
Germany covering the period from 1983 to 2015 (33 years) based on satellite estimates of
direct normalised surface solar radiation and in situ sunshine duration observations
using
a geostatistical approach.
The CM SAF SARAH direct normalized irradiance (DNI) satellite climate data record
and in situ observations of sunshine duration from 121 weather stations operated by DWD are
used as input datasets. The selected period of 33 years is associated with the availability of
satellite data. The number of ground stations is limited to 121 as there are only
time series with less than 10% of missing observations over the selected period
included to keep the long-term consistency of the output sunshine duration data
record.
In the first step, DNI data record is used to derive sunshine hours by applying WMO
threshold of 120 W/m2 (SDU = DNI ≥ 120 W/m2) and weighting of sunny slots to
correct the sunshine length between two instantaneous image data due to cloud
movement. In the second step, linear regression between SDU and in situ sunshine
duration is calculated to adjust the satellite product to the ground observations and the
output regression coefficients are applied to create a regression grid. In the last step
regression residuals are interpolated with ordinary kriging and added to the regression
grid. A comprehensive accuracy assessment of the gridded sunshine duration data
record is performed by calculating prediction errors (cross-validation routine). “R” is
used for data processing. A short analysis of the spatial distribution and temporal
variability of sunshine duration over Germany based on the created dataset will be
presented.
The gridded sunshine duration data are useful for applications in various climate-related
studies, agriculture and solar energy potential calculations. |
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