dorsal/arxiv
View SchemaDiscrepancies in Southern Hemisphere Mid-latitude Atmospheric Variability of the NCEP-NCAR and ECMWF Reanalyses
| Authors | A. Dell'Aquila, P. M. Ruti, S. Calmanti, V. Lucarini |
|---|---|
| Categories | |
| ArXiv ID | physics/0509145 |
| URL | https://arxiv.org/abs/physics/0509145 |
| DOI | 10.1007/s00382-005-0048-x |
Abstract
In this study we compare the representation of the southern hemisphere midlatitude winter variability in the NCEP-NCAR and ERA40 reanalyses. We use the classical Hayashi spectral technique, recently applied to compare the description of the atmospheric variability in the northern hemisphere on different spectral sub-domains. We test the agreement of the two reanalysis systems in the representation of the atmospheric activity. In the southern hemisphere, even in the satellite period, the assimilated data are relatively scarce, predominately over the oceans, and they provide a weaker constraint to the model dynamics. We find relevant discrepancies in the description of the variability at different spatial and temporal scales. ERA40 is generally characterised by a larger variance, especially in the high frequency spectral region. In the pre-satellite period the discrepancies between the two reanalyses are large and randomly distributed while after the 1979 the discrepancies are systematic. Moreover, a sudden jump in the VTPR period (1973-1978) is observed, mostly in the ERA40 reanalysis. Our results suggest that today we do not have a well-defined picture of the properties of the winter mid-latitude variability in the southern hemisphere to be used in the evaluation of the realism of climate models and demand for an intercomparison study for the assessment of the self-consistency of the IPCC models in the representation of the analysed properties.
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"abstract": "In this study we compare the representation of the southern hemisphere\nmidlatitude winter variability in the NCEP-NCAR and ERA40 reanalyses. We use\nthe classical Hayashi spectral technique, recently applied to compare the\ndescription of the atmospheric variability in the northern hemisphere on\ndifferent spectral sub-domains. We test the agreement of the two reanalysis\nsystems in the representation of the atmospheric activity. In the southern\nhemisphere, even in the satellite period, the assimilated data are relatively\nscarce, predominately over the oceans, and they provide a weaker constraint to\nthe model dynamics. We find relevant discrepancies in the description of the\nvariability at different spatial and temporal scales. ERA40 is generally\ncharacterised by a larger variance, especially in the high frequency spectral\nregion. In the pre-satellite period the discrepancies between the two\nreanalyses are large and randomly distributed while after the 1979 the\ndiscrepancies are systematic. Moreover, a sudden jump in the VTPR period\n(1973-1978) is observed, mostly in the ERA40 reanalysis. Our results suggest\nthat today we do not have a well-defined picture of the properties of the\nwinter mid-latitude variability in the southern hemisphere to be used in the\nevaluation of the realism of climate models and demand for an intercomparison\nstudy for the assessment of the self-consistency of the IPCC models in the\nrepresentation of the analysed properties.",
"arxiv_id": "physics/0509145",
"authors": [
"A. Dell\u0027Aquila",
"P. M. Ruti",
"S. Calmanti",
"V. Lucarini"
],
"categories": [
"physics.ao-ph",
"physics.data-an",
"physics.flu-dyn",
"physics.geo-ph"
],
"doi": "10.1007/s00382-005-0048-x",
"title": "Discrepancies in Southern Hemisphere Mid-latitude Atmospheric Variability of the NCEP-NCAR and ECMWF Reanalyses",
"url": "https://arxiv.org/abs/physics/0509145"
},
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