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Spring Cold Bias of SST and Minimal Wind Mixing in the Equatorial Pacific Cold Tongue
Atmospheric and Oceanic Science Letters, Volume 3 Number 6. Lin Peng-Fei; Liu Hai-Long; Li Chao; et al. - Science Press, 2010The authors investigate the relationship between bias in simulated sea surface temperature (SST) in the equatorial eastern Pacific cold tongue during the boreal spring as simulated by an oceanic general circulation model (OGCM) and minimal wind mixing (MWM) at the surface. The cold bias of simulated SST is greatest during the boreal spring, at approximately 3°C. A sensitivity experiment reducing MWM by one order of magnitude greatly alleviates cold biases, especially in March-April. The decrease in bias is primarily due to weakened vertical mixing, which preserves heat in the uppermost layer a ...
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Available online: http://www.iapjournals.ac.cn/aosl/ch/reader/view_abstract.aspx?file_no=AOSL10057
in Atmospheric and Oceanic Science Letters > Volume 3 Number 6 (16 November 2010) . - p.342-346The authors investigate the relationship between bias in simulated sea surface temperature (SST) in the equatorial eastern Pacific cold tongue during the boreal spring as simulated by an oceanic general circulation model (OGCM) and minimal wind mixing (MWM) at the surface. The cold bias of simulated SST is greatest during the boreal spring, at approximately 3°C. A sensitivity experiment reducing MWM by one order of magnitude greatly alleviates cold biases, especially in March-April. The decrease in bias is primarily due to weakened vertical mixing, which preserves heat in the uppermost layer and results in warmer simulated SST. The reduction in vertical mixing also leads to a weak westward current in the upper layer, which further contributes to warmer SST estimates. These findings imply that there are large uncertainties about simple model parameters such as MWM at the oceanic surface.
Language(s): English
Format: Digital (Free), Hard copyTags: Temperature anomaly ; Severe cold ; Meteorology ; Observations ; Spring ; Weather ; Wind ; Region V - South-West Pacific
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Interannual Variability of Snow Depth over the Tibetan Plateau and Its Associated Atmospheric Circulation Anomalies
The interannual variability of wintertime snow depth over the Tibetan Plateau (TP) and related atmospheric circulation anomalies were investigated based on observed snow depth measurements and NCEP/NCAR reanalysis data. Empirical orthogonal function (EOF) analysis was applied to identify the spatio-temporal variability of wintertime TP snow depth. Snow depth anomalies were dominated by a monopole pattern over the TP and a dipole structure with opposite anomalies over the southeastern and northwestern TP. The atmospheric circulation conditions responsible for the interannual variability of TP s ...
[article]Interannual Variability of Snow Depth over the Tibetan Plateau and Its Associated Atmospheric Circulation Anomalies
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Available online: http://www.iapjournals.ac.cn/aosl/ch/reader/view_abstract.aspx?file_no=AOSL10047
in Atmospheric and Oceanic Science Letters > Volume 3 Number 4 (16 July 2010) . - p.213-218The interannual variability of wintertime snow depth over the Tibetan Plateau (TP) and related atmospheric circulation anomalies were investigated based on observed snow depth measurements and NCEP/NCAR reanalysis data. Empirical orthogonal function (EOF) analysis was applied to identify the spatio-temporal variability of wintertime TP snow depth. Snow depth anomalies were dominated by a monopole pattern over the TP and a dipole structure with opposite anomalies over the southeastern and northwestern TP. The atmospheric circulation conditions responsible for the interannual variability of TP snow depth were examined via regression analyses against the principal component of the most dominant EOF mode. In the upper troposphere, negative zonal wind anomalies over the TP with extensively positive anomalies to the south indicated that the southwestward shift of the westerly jet may favor the development of surface cyclones over the TP. An anomalous cyclone centered over the southeastern TP was associated with the anomalous westerly jet, which is conducive to heavier snowfall and results in positive snow depth anomalies. An anomalous cyclone was observed at 500 hPa over the TP, with an anomalous anticyclone immediately to the north, suggesting that the TP is frequently affected by surface cyclones. Regression analyses revealed that significant negative thickness anomalies exist around the TP from March to May, with a meridional dipole anomaly in March. The persistent negative anomalies due to more winter TP snow are not conducive to earlier reversal of the meridional temperature gradient, leading to a possible delay in the onset of the Asian summer monsoon.
Language(s): English
Format: Digital (Free), Hard copyTags: Temperature anomaly ; Atmospheric circulation ; Snow ; Ozone ; Seasonal change ; China ; Tibet, China
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Seasonal prediction of sea surface temperatures anomalies using a suite of 13 coupled atmosphere-ocean models
Improved seasonal prediction of sea surface temperature (SST) anomalies over the global oceans is the theme of this paper. Using 13 state-of-the-art coupled global atmosphere-ocean models and 13 yr of seasonal forecasts, the performance of individual models, the ensemble mean, the bias-removed ensemble mean, and the Florida State University (FSU) superensemble are compared. A total of 23 400 seasonal forecasts based on 1-month lead times were available for this study. Evaluation metrics include both deterministic and probabilistic skill measures, such as verification of anomalies based on mode ...
Seasonal prediction of sea surface temperatures anomalies using a suite of 13 coupled atmosphere-ocean models
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Available online: http://journals.ametsoc.org/doi/pdf/10.1175/JCLI3938.1
T.N. Krishnamurti ; Arindam Chakraborty ; Ruby Krishnamurti ; Florida State University (United States)
Published by: FSU ; 2006Improved seasonal prediction of sea surface temperature (SST) anomalies over the global oceans is the theme of this paper. Using 13 state-of-the-art coupled global atmosphere-ocean models and 13 yr of seasonal forecasts, the performance of individual models, the ensemble mean, the bias-removed ensemble mean, and the Florida State University (FSU) superensemble are compared. A total of 23 400 seasonal forecasts based on 1-month lead times were available for this study. Evaluation metrics include both deterministic and probabilistic skill measures, such as verification of anomalies based on model and observed climatology, time series of specific climate indices, standard deterministic ensemble mean scores including anomaly correlations, root-mean-square (RMS) errors, and probabilistic skill measures such as equitable threat scores for seasonal SST forecasts. This study also illustrates the Niño-3.4 SST forecast skill for the equatorial Pacific Ocean and for the dipole index for the Indian Ocean. The relative skills of total SST fields and of the SST anomalies from the 13 coupled atmosphere-ocean models are presented. Comparisons of superensemble-based seasonal forecasts with recent studies on SST anomaly forecasts are also shown. Overall it is found that the multimodel superensemble forecasts are characterized by considerable RMS error reductions and increased accuracy in the spatial distribution of SST. Superensemble SST skill also persists for El Niño and La Niña forecasts since the large comparative skill of the superensemble is retained across such years. Real-time forecasts of seasonal sea surface temperature anomalies appear to be possible.
Language(s): English
Format: Digital (Free) (ill., charts, maps)Tags: Oceans ; Ocean model ; Seasonal forecast ; Temperature anomaly ; National Meteorological and Hydrological Service (NMHS) ; Modelling
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Published by: BMO ; 2001
Language(s): Russian; Other Languages: English, French, Spanish
Format: Digital (Free) (ill., charts, maps)Tags: Weather ; Climate ; Climate change ; Temperature anomaly
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Conditions météorologiques et climatiques, variabilité et évolution : le développement durable après 2002
Conditions météorologiques et climatiques, variabilité et évolution: le développement durable après 2002
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Published by: OMM ; 2001
Language(s): French; Other Languages: English, Russian, Spanish
Format: Digital (Free) (ill., charts, maps)Tags: Weather ; Climate ; Climate change ; Temperature anomaly
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