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Selected Publication:

Publication type: Doctoral Thesis

Year: 2007

Author(s): Kottek, M

Title: Beiträge zur globalen Klimatologie von Wolken und Niederschlag.

Source: Dissertation, Univ. Wien, pp. 100.


Advisor(s):

Rubel Franz,


Project(s): GEOLAND - GMES Products & Services supporting the Implementation of European Directives and International Policies & Conventions linked to "Land Cover & Vegetation"


Abstract:
The dissertation presented here summarises applications to the results of the volume ¿Observed Global Climate¿ of the series Landolt-Börnstein - Numerical Data and Functional Relationships in Science and Technology and following contributions of the author to the project GEOLAND. Within the data management of the Landolt-Börnstein a standardised collection of 20 data sets containing more than 100 climate budget elements describing the current state of the climate was produced and archived for the period 1991 to 1995. In a first application the ISCCP data set was used to analyse the cloud effects on the global radiation budget. Possibly for the first time global fields of the gain or loss of the radiant energy of the atmosphere (vertical radiative flux divergence) and the effect of the clouds on it could be shown. Furthermore, based on recent monthly temperature and precipitation data an updated digital world map of the Köppen-Geiger climate classification was calculated for the second half of the 20th century and used for a characterisation of the global climate change. Comparing sliding 15-year intervals of this climate map for the period 1951 to 2000 results in an overview of the spatio-temporal variations of the main climates. Thus, for the end of the 20th century an areal increase of the arid climate (+0.78 % of the global land area) with a concurrent decrease of the snow climate (-0.46 %) and the polar climate (-0.53 %) and only minor expansions for the equatorial climate (+0.09 %) and the warm temperate climate (+0.12 %) has been determined. The updated world map of the Köppen-Geiger climate classification was also used within the project GEOLAND for the development of a global scale daily precipitation product based on bias-corrected rain gauge measurements. Despite the efforts undertaken in the last decades a near real-time global daily precipitation product based not only, as usual, on satellite estimates but also and particularly on operational ground measurements was still missing today. For the compilation of such a precipitation product geostatistical methods were used. The regionalisation of the statistical structure of the precipitation was carried out by spatial correlation functions for the 5 main climates of the earth. The results of this new method are two global daily precipitation data sets for the period 1996 up to present. Comparing to existing satellite estimates a verification over the land areas shows an essential improvement of the accuracy: Over Europe e.g. the rank-order correlation coefficient increases from 0.49 to 0.86 and the true skill score increases from 0.36 to 0.67.

Keywords:
climatology / clouds / precipitation / climate classification / climate change / precipitation product / gauge measurements / multi-satellite estimates


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