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11.
Michelle Simões Reboita Rosmeri Porfírio da Rocha Tércio Ambrizzi Ernesto Caetano 《Climate Dynamics》2010,34(6):873-889
A Regional Climate Model (RegCM3) 10-year (1990–1999) simulation over southwestern South Atlantic Ocean (SAO) is evaluated
to assess the mean climatology and the simulation errors of turbulent fluxes over the sea. Moreover, the relationship between
these fluxes and the rainfall over some cyclogenetic areas is also analyzed. The RegCM3 results are validated using some reanalyses
datasets (ERA40, R2, GPCP and WHOI). The summer and winter spatial patterns of latent and sensible heat fluxes simulated by
the RegCM3 are in agreement with the reanalyses (WHOI, R2 and ERA40). They show large latent heat fluxes exchange in the subtropical
SAO and at higher latitudes in the warm waters of Brazil Current. In particular, the magnitude of RegCM3 latent heat fluxes
is similar to the WHOI, which is probably related to two factors: (a) small specific humidity bias, and (b) the RegCM3 flux
algorithm. In contrast, the RegCM3 presents large overestimation of sensible heat flux, though it simulates well their spatial
pattern. This simulation error is associated with the RegCM3 underestimation of the 2-m air temperature. In southwestern SAO,
in three known cyclogenetic areas, the reanalyses and the RegCM3 show the existence of different physical mechanisms that
control the annual cycles of latent/sensible heating and rainfall. It is shown that over the eastern coast of Uruguay (35°–43°S)
and the southeastern coast of Argentina (44°–52°S) the sea-air moisture and heat exchange play an important role to control
the annual cycle of precipitation. This does not happen on the south/southeastern coast of Brazil. 相似文献
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Michelle Simões Reboita Rosmeri Porfírio da Rocha Tércio Ambrizzi Shigetoshi Sugahara 《Climate Dynamics》2010,35(7-8):1331-1347
A detailed climatology of the cyclogenesis over the Southern Atlantic Ocean (SAO) from 1990 to 1999 and how it is simulated by the RegCM3 (Regional Climate Model) is presented here. The simulation used as initial and boundary conditions the National Centers for Environmental Prediction—Department of Energy (NCEP/DOE) reanalysis. The cyclones were identified with an automatic scheme that searches for cyclonic relative vorticity (ζ10) obtained from a 10-m height wind field. All the systems with ζ10 ≤ ?1.5 × 10?5 s?1 and lifetime equal or larger than 24 h were considered in the climatology. Over SAO, in 10 years were detected 2,760 and 2,787 cyclogeneses in the simulation and NCEP, respectively, with an annual mean of 276.0 ± 11.2 and 278.7 ± 11.1. This result suggests that the RegCM3 has a good skill to simulate the cyclogenesis climatology. However, the larger model underestimations (?9.8%) are found for the initially stronger systems (ζ10 ≤ ?2.5 × 10?5 s?1). It was noted that over the SAO the annual cycle of the cyclogenesis depends of its initial intensity. Considering the systems initiate with ζ10 ≤ ?1.5 × 10?5 s?1, the annual cycle is not well defined and the higher frequency occurs in the autumn (summer) in the NCEP (RegCM3). The stronger systems (ζ10 ≤ ?2.5 × 10?5 s?1) have a well-characterized high frequency of cyclogenesis during the winter in both NCEP and RegCM3. This work confirms the existence of three cyclogenetic regions in the west sector of the SAO, near the South America east coast and shows that RegCM3 is able to reproduce the main features of these cyclogenetic areas. 相似文献
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H. Evangelista D. Godiva A. Sifeddine Z. M. A. N. Leão N. R. Rigozo B. Segal T. Ambrizzi M. Kampel R. K. P. Kikuchi F. Le Cornec 《Climate Dynamics》2007,29(7-8):869-880
Physical and biological changes in the marine environment, induced by oceanic-atmospheric processes, can be imprinted in massive coral skeletons. Herein, we present an evidence of potential El Niño impacts at the Southwestern South Atlantic Ocean (SWSA) inferred from the sclerochronology of the reef coral Favia leptophylla. The application of spectral analysis (wavelet decomposition and the iterative regression) to coral growth length and to meteorological-oceanographic parameters (air temperature, sea surface temperature and precipitation) as well as to Southern Oscillation Index (SOI) and solar irradiation indicated a major significant inverse relationship between SOI and coral growth length at the 4–8 years frequency band. We propose here that coral growth length from the SWSA could be affected by El Niño Southern Oscillation (ENSO) events through an “atmospheric bridge”, in contrast to its direct effect at the Pacific Ocean, related to the increase in sea surface temperature. 相似文献
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The role of SST on the South American atmospheric circulation during January, February and March 2001 总被引：1，自引：0，他引：1
Precipitation deficits were observed over southeastern, northeastern and Central Brazil during the 2001 Austral Summer. They
contributed to the worsening of the energy crisis that was occurring in the country. A low-level anomalous anticyclonic circulation
observed over eastern Brazil enhanced the deviation of moisture transport that usually occurs from the Amazon Basin to southeastern
Brazil and inhibited the occurrence of South Atlantic Convergence Zone events in that period. However, an anomalous low-level
northerly moisture flux was observed over the La Plata Basin, and positive precipitation anomalies occurred over Bolivia,
Paraguay, northeastern Argentina and southern Brazil. Using the ensemble technique, a numerical study was carried out to investigate
the role of different sea surface temperature (SST) forcings observed over this anomalous South American atmospheric circulation.
Reynolds SST monthly means were used as boundary conditions to study the influence of South Atlantic, South Indian, South
Pacific and Equatorial Pacific oceans. The simulations were run from September 2000 to April 2001 using the Community Climate
Model version 3.6 General Circulation Model. Ten integrations using different initial conditions were done to each experiment.
Numerical experiments suggested that the combined influence of South Pacific and Equatorial Pacific oceans could be responsible
for the drought observed over Central Brazil. These experiments simulated the low-level anticyclonic anomaly observed over
eastern Brazil. However, both experiments have poorly reproduced the intensity of the anomalous low-level northerly moisture
flux observed over the La Plata Basin. Therefore, the intensity of the simulated precipitation anomalies over the subtropical
regions was much weaker than observed. 相似文献
17.
Exploring the impacts of the tropical Pacific SST on the precipitation patterns over South America during ENSO periods 总被引：2，自引：0，他引：2
Summary
Previous studies on precipitation over South America that strongly support the existence of links between precipitation and
SST anomalies in the Pacific Ocean have identified specific regions where the ENSO signal is particularly stronger. Northeast
of Brazil and some parts of southern South America are examples of these regions. However, the same attention was not taken
to identify which regions in the Central and East Pacific ocean are better correlated with the South America precipitation
during extreme ENSO events, and also which are the transition regions of the precipitation signal over South America during
these events.
Coincident periods of ENSO events for both SST over the tropical Pacific ocean and monthly precipitation sums from many observational
stations over South America were selected and analyzed. Two statistical methods were used for the data analysis: Singular
Value Decomposition (SVD) and Simple Linear Correlation (SLC). The SVD results for warmer events in the Pacific corroborate
previous ones and also clearly identified a transition region between the drier conditions in the Northeast of Brazil and
the wetter conditions in the Southeast/South of Brazil. Transition regions were also determined over Peru and central Amazon.
The SLC results indicated that the SST anomalies in the tropical east Pacific ocean has the strongest influence in the South
American precipitation during El Ni?o events. During La Ni?a events the central area of the Pacific, around 180°, has shown
a more significant influence.
Received August 10, 2000 Revised August 22, 2001 相似文献
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Caio A. S. Coelho Cristiano Prestrelo de Oliveira Tércio Ambrizzi Michelle Simões Reboita Camila Bertoletti Carpenedo José Leandro Pereira Silveira Campos Ana Carolina Nóbile Tomaziello Luana Albertani Pampuch Maria de Souza Custódio Lívia Marcia Mosso Dutra Rosmeri P. Da Rocha Amanda Rehbein 《Climate Dynamics》2016,46(11-12):3737-3752
20.
Gyrlene Aparecida Mendes da Silva T. Ambrizzi 《Theoretical and Applied Climatology》2010,101(3-4):303-310
The impact of the inter-El Niño (EN) variability on the moisture availability over Southeastern South America (SESA) is investigated. Also, an automatic tracking scheme was used to analyze the extratropical cyclones properties (system density - SD and central pressure - CP) in this region. During the austral summer period from 1977–2000, the differences for the upper-level wave train anomaly composites seem to determine the rainfall composite differences. In fact, the positive rainfall anomalies over most of the SESA domain during the strong EN events are explained by an upper-level cyclonic center over the tropics and an anticyclonic center over the eastern subtropical area. This pattern seems to contribute to upward vertical motion at 500 hPa and reinforcement of the meridional moisture transport from the equatorial Atlantic Ocean and western Amazon basin to the SESA region. These features may contribute to the positive SD and negative CP anomalies explaining part of the positive rainfall anomalies found there. On the other hand, negative rainfall anomalies are located in the northern part of SESA for the weak EN years when compared to those for the strong events. Also, positive anomalies are found in the southern part, albeit less intense. It was associated with the weakening of the meridional moisture transport from the tropics to the SESA that seems have to contributed with smaller SD and CP anomalies over the most part of subtropics, when compared to the strong EN years. 相似文献