In this paper, sound scattering from the sea surface in the Persian Gulf region is investigated. Chapman-Harris and Ogden-Erskine empirical relations coupled with perturbation theory are implemented. Based on the Ogde...In this paper, sound scattering from the sea surface in the Persian Gulf region is investigated. Chapman-Harris and Ogden-Erskine empirical relations coupled with perturbation theory are implemented. Based on the Ogden and Erskine＇s experiments, sound scattering from the sea surface has three different regimes in which two mechanisms of surface roughness and subsurface bubble clouds are involved. Ogden-Erskine＇s scattering relation which consists of perturbation theory and Chapman-Harris＇s scattering terms are verified by the experimental data of Critical Sea Tests 7. Subsequently, wind speed in the Persian Gulf is provided based on three data bases of Arzanah station, ERA40, and PERGOS. Accordingly, surface scattering strength in the Persian Gulf region is calculated at different grazing angles, frequencies and provided wind speeds. Based on the resulted values of scattering strength, scattered intensity from the sea surface is also studied. These studies indicate that both scattering strength and scattered intensity generally increase as grazing angle, frequency and wind speed increase.展开更多
By using monthly historical sea surface temperature (SST) data for the yearsfrom 1950 to 2000, the Western Pacific Warm Pool (WPWP) climatology and anomalies are studied inthis paper. The analysis of WPWP centroid (WP...By using monthly historical sea surface temperature (SST) data for the yearsfrom 1950 to 2000, the Western Pacific Warm Pool (WPWP) climatology and anomalies are studied inthis paper. The analysis of WPWP centroid (WPWPC) movement anomalies and the Nino-3 region SSTanomalies(SSTA) seems to reveal a close, linear relation between the zonal WPWPC and Nino-3 regionSSTA, which suggests that a 9° anomaly of the zonal displacement from the climatological positionof the WPWPC corresponds to about a 1℃ anomaly in the Nino-3 region area-mean SST. This studyconnects the WPWPC zonal displacement with the Nino-3 SSTA, and it may be helpful in betterunderstanding the fact that the WPWP eastward extension is conducive to the Nino-3 region SSTincrease during an El Nino-Southern Oscillation (ENSO) event.展开更多
Upper ocean heat content is a factor critical to the intensity change of tropical cyclones(TCs). Because of the inhomogeneity of in situ observations in the North Indian Ocean,gridded temperature/salinity(T/S) profile...Upper ocean heat content is a factor critical to the intensity change of tropical cyclones(TCs). Because of the inhomogeneity of in situ observations in the North Indian Ocean,gridded temperature/salinity(T/S) profiles were derived from satellite data for 1993–2012 using a linear regression method. The satellite derived T/S dataset covered the region of 10°S–32°N,25°–100°E with daily temporal resolution,0.25°×0.25° spatial resolution,and 26 vertical layers from the sea surface to a depth of 1 000 m at standard layers. Independent Global Temperature Salinity Profile Project data were used to validate the satellite derived T/S fields. The analysis confirmed that the satellite derived temperature field represented the characteristics and vertical structure of the temperature field well. The results demonstrated that the vertically averaged root mean square error of the temperature was 0.83 in the upper 1 000 m and the corresponding correlation coefficient was 0.87,which accounted for 76% of the observed variance. After verification of the satellite derived T/S dataset,the TC heat potential(TCHP) was verified. The results show that the satellite derived values were coherent with observed TCHP data with a correlation coefficient of 0.86 and statistical significance at the 99% confidence level. The intensity change of TC Gonu during a period of rapid intensification was studied using satellite derived TCHP data. A delayed effect of the TCHP was found in relation to the intensity change of Gonu,suggesting a lag feature in the response of the inner core of the TC to the ocean.展开更多
The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails t...The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails to explain many climate phenomena. Here, another multidecadal variability over the North Pacific is described, found by analyzing reconstructed data covering the past 140 years. It is named the Pacific Multidecadal Oscillation （PMO）, with anomalously high/low SSTs over the northeastern Pacific, and a quasi-60-year cycle. Related to this low-frequency variability of SST, the global mean temperature and precipitation present significant interdecadal differences. More importantly, the PMO index leads the global mean surface air temperature and SST by one to three years. The Arctic Oscillation pattern and atmospheric circulations are shown to change substantially with the transition of the PMO mode from positive to negative phases. This multidecadal oscillation improves the prospect for a long-term forecast of the global warming trend, since the PMO bears a remarkable relationship with global temperature.展开更多
The scatterometer （SCAT） on-board China＇s HY-2A satellite has the capability to provide high resolution wind vector information over the global ocean surface. These wind vector data produced by the HY-2A scatterome...The scatterometer （SCAT） on-board China＇s HY-2A satellite has the capability to provide high resolution wind vector information over the global ocean surface. These wind vector data produced by the HY-2A scatterometer （HY-2A SCAT） are available to the data assimilation system with real-time information of high accuracy. In this paper, two experiments are designed to investigate the impact of HY-2A SCAT data in the three- dimensional variational assimilation system for the Weather Research and Forecast model （WRF 3DVAR）. The powerful Typhoon Bolaven, which struck South Korea in August 2012, is selected for this case study. The results clearly demonstrate that HY-2A SCAT data can effectively complement the scarce observations over the ocean surface and improve the prediction of the wind and pressure fields of a typhoon. The case study of Typhoon Bolaven exhibits the significant and positive impact of HY- 2A SCAT data on the numerical prediction of the tropical cyclone track.展开更多
文摘In this paper, sound scattering from the sea surface in the Persian Gulf region is investigated. Chapman-Harris and Ogden-Erskine empirical relations coupled with perturbation theory are implemented. Based on the Ogden and Erskine＇s experiments, sound scattering from the sea surface has three different regimes in which two mechanisms of surface roughness and subsurface bubble clouds are involved. Ogden-Erskine＇s scattering relation which consists of perturbation theory and Chapman-Harris＇s scattering terms are verified by the experimental data of Critical Sea Tests 7. Subsequently, wind speed in the Persian Gulf is provided based on three data bases of Arzanah station, ERA40, and PERGOS. Accordingly, surface scattering strength in the Persian Gulf region is calculated at different grazing angles, frequencies and provided wind speeds. Based on the resulted values of scattering strength, scattered intensity from the sea surface is also studied. These studies indicate that both scattering strength and scattered intensity generally increase as grazing angle, frequency and wind speed increase.
文摘By using monthly historical sea surface temperature (SST) data for the yearsfrom 1950 to 2000, the Western Pacific Warm Pool (WPWP) climatology and anomalies are studied inthis paper. The analysis of WPWP centroid (WPWPC) movement anomalies and the Nino-3 region SSTanomalies(SSTA) seems to reveal a close, linear relation between the zonal WPWPC and Nino-3 regionSSTA, which suggests that a 9° anomaly of the zonal displacement from the climatological positionof the WPWPC corresponds to about a 1℃ anomaly in the Nino-3 region area-mean SST. This studyconnects the WPWPC zonal displacement with the Nino-3 SSTA, and it may be helpful in betterunderstanding the fact that the WPWP eastward extension is conducive to the Nino-3 region SSTincrease during an El Nino-Southern Oscillation (ENSO) event.
基金Supported by the National Basic Research Program of China(973 Program)(No.2013CB430304)the National Natural Science Foundation of China(Nos.41030854,41106005,41176003,41206178,41376015,41376013,41306006)the National High-Tech R&D Program of China(No.2013AA09A505)
文摘Upper ocean heat content is a factor critical to the intensity change of tropical cyclones(TCs). Because of the inhomogeneity of in situ observations in the North Indian Ocean,gridded temperature/salinity(T/S) profiles were derived from satellite data for 1993–2012 using a linear regression method. The satellite derived T/S dataset covered the region of 10°S–32°N,25°–100°E with daily temporal resolution,0.25°×0.25° spatial resolution,and 26 vertical layers from the sea surface to a depth of 1 000 m at standard layers. Independent Global Temperature Salinity Profile Project data were used to validate the satellite derived T/S fields. The analysis confirmed that the satellite derived temperature field represented the characteristics and vertical structure of the temperature field well. The results demonstrated that the vertically averaged root mean square error of the temperature was 0.83 in the upper 1 000 m and the corresponding correlation coefficient was 0.87,which accounted for 76% of the observed variance. After verification of the satellite derived T/S dataset,the TC heat potential(TCHP) was verified. The results show that the satellite derived values were coherent with observed TCHP data with a correlation coefficient of 0.86 and statistical significance at the 99% confidence level. The intensity change of TC Gonu during a period of rapid intensification was studied using satellite derived TCHP data. A delayed effect of the TCHP was found in relation to the intensity change of Gonu,suggesting a lag feature in the response of the inner core of the TC to the ocean.
基金supported by the National Natural Science Foundation of China[grant number 41421004],[grant number41130103]
文摘The internal modes of the North Pacific can lead to climatic oscillations through ocean-atmosphere interactions and induce global climate responses.The best example is the Pacific Decadal Oscillation, but this fails to explain many climate phenomena. Here, another multidecadal variability over the North Pacific is described, found by analyzing reconstructed data covering the past 140 years. It is named the Pacific Multidecadal Oscillation （PMO）, with anomalously high/low SSTs over the northeastern Pacific, and a quasi-60-year cycle. Related to this low-frequency variability of SST, the global mean temperature and precipitation present significant interdecadal differences. More importantly, the PMO index leads the global mean surface air temperature and SST by one to three years. The Arctic Oscillation pattern and atmospheric circulations are shown to change substantially with the transition of the PMO mode from positive to negative phases. This multidecadal oscillation improves the prospect for a long-term forecast of the global warming trend, since the PMO bears a remarkable relationship with global temperature.
文摘The scatterometer （SCAT） on-board China＇s HY-2A satellite has the capability to provide high resolution wind vector information over the global ocean surface. These wind vector data produced by the HY-2A scatterometer （HY-2A SCAT） are available to the data assimilation system with real-time information of high accuracy. In this paper, two experiments are designed to investigate the impact of HY-2A SCAT data in the three- dimensional variational assimilation system for the Weather Research and Forecast model （WRF 3DVAR）. The powerful Typhoon Bolaven, which struck South Korea in August 2012, is selected for this case study. The results clearly demonstrate that HY-2A SCAT data can effectively complement the scarce observations over the ocean surface and improve the prediction of the wind and pressure fields of a typhoon. The case study of Typhoon Bolaven exhibits the significant and positive impact of HY- 2A SCAT data on the numerical prediction of the tropical cyclone track.
