Change search
ReferencesLink to record
Permanent link

Direct link
How well do reanalyses represent the southern African precipitation?
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
2013 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, no 3-4, 951-962 p.Article in journal (Refereed) Published
Abstract [en]

Monthly-mean precipitation observations over southern Africa are used to evaluate the performance of eight global reanalyses: ERA-40, ERA-interim, JRA-25, MERRA, CFSR, NCEP-R1, NCEP-R2 and 20CRv2. All eight reanalyses reproduce the regionally averaged seasonal cycle fairly well; a few spatial mismatches with the observations are found in the climate mean for the rainy season. Principal component analyses show a dipole in the leading modes of all reanalyses, however with crucial differences in its spatial position. Possible reasons for the differences between the reanalyses are discussed on the basis of the ERA-interim and 20CRv2 results. A comparison between the moisture transports shows that ERA-interim manifests a very strong moisture convergence over the eastern equatorial Atlantic, resulting in the strong precipitation here. This excessive convergence may be due to the water-vapor assimilation and convection parameterization. Over the Indian Ocean, the ITCZ is shifted northward in ERA-interim compared to its position in 20CRv2. This discrepancy is most likely attributable to the meridional SST gradients in the Indian Ocean which are significantly larger in the ERA-interim than those in the 20CRv2, and the resulting atmospheric response prevents a southward shift of the ITCZ. Overall, the consistent description of the dynamical circulation of the atmosphere and the hydrological cycle appears as a crucial benchmark for reanalysis data. Based on our evaluation, the preferential reanalysis for investigating the climate variability over southern Africa is 20CRv2 that furthermore spans the longest time period, hence permitting the most precise investigations of interannual to decadal variability.

Place, publisher, year, edition, pages
2013. Vol. 40, no 3-4, 951-962 p.
Keyword [en]
Reanalysis, Precipitation, Southern Africa, Hydrological cycle, Dipole
National Category
Meteorology and Atmospheric Sciences
URN: urn:nbn:se:su:diva-88266DOI: 10.1007/s00382-012-1423-zISI: 000314292200025OAI: diva2:610823
Swedish Research Council


Available from: 2013-03-13 Created: 2013-03-12 Last updated: 2013-03-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Zhang, QiongKörnich, HeinerHolmgren, Karin
By organisation
Department of Physical Geography and Quaternary GeologyDepartment of Meteorology
In the same journal
Climate Dynamics
Meteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 66 hits
ReferencesLink to record
Permanent link

Direct link