dorsal/arxiv
View SchemaHayashi Spectra of the Northern Hemisphere Mid-latitude Atmospheric Variability in the NCEP and ERA 40 Reanalyses
| Authors | Alessandro Dell'Aquila, Valerio Lucarini, Paolo Ruti, Sandro Calmanti |
|---|---|
| Categories | |
| ArXiv ID | physics/0412150 |
| URL | https://arxiv.org/abs/physics/0412150 |
Abstract
We compare 45 years of the reanalyses of NCEP-NCAR and ECMWF in terms of their representation of the mid-latitude winter atmospheric variability for the overlapping time frame 1957-2002. We adopt the classical approach of computing the Hayashi spectra of the 500 hPa geopotential height fields. Discrepancies are found especially in the first 15 years of the records in the high-frequency-high wavenumber propagating waves and secondly on low frequency-low wavenumber standing waves. This implies that in the first period the two datasets have a different representation of the baroclinic available energy conversion processes. In the period starting from 1973 a positive impact of the aircraft data on the Euro-Atlantic synoptic waves has been highlighted. Since in the first period the assimilated data are scarcer and of lower quality than later on, they provide a weaker constraint to the model dynamics. Therefore, the resulting discrepancies in the reanalysis products may be mainly attributed to differences in the models' behavior.
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"abstract": "We compare 45 years of the reanalyses of NCEP-NCAR and ECMWF in terms of\ntheir representation of the mid-latitude winter atmospheric variability for the\noverlapping time frame 1957-2002. We adopt the classical approach of computing\nthe Hayashi spectra of the 500 hPa geopotential height fields. Discrepancies\nare found especially in the first 15 years of the records in the\nhigh-frequency-high wavenumber propagating waves and secondly on low\nfrequency-low wavenumber standing waves. This implies that in the first period\nthe two datasets have a different representation of the baroclinic available\nenergy conversion processes. In the period starting from 1973 a positive impact\nof the aircraft data on the Euro-Atlantic synoptic waves has been highlighted.\nSince in the first period the assimilated data are scarcer and of lower quality\nthan later on, they provide a weaker constraint to the model dynamics.\nTherefore, the resulting discrepancies in the reanalysis products may be mainly\nattributed to differences in the models\u0027 behavior.",
"arxiv_id": "physics/0412150",
"authors": [
"Alessandro Dell\u0027Aquila",
"Valerio Lucarini",
"Paolo Ruti",
"Sandro Calmanti"
],
"categories": [
"physics.ao-ph",
"physics.flu-dyn",
"physics.geo-ph"
],
"title": "Hayashi Spectra of the Northern Hemisphere Mid-latitude Atmospheric Variability in the NCEP and ERA 40 Reanalyses",
"url": "https://arxiv.org/abs/physics/0412150"
},
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