The modulation of twin tropical cyclogenesis in the Indian-western Pacific Oceans by the Madden-Julian Oscillation (MJO) during the onset period of 1997/98 ENSO is explored for the period of September 1996 to June 199...The modulation of twin tropical cyclogenesis in the Indian-western Pacific Oceans by the Madden-Julian Oscillation (MJO) during the onset period of 1997/98 ENSO is explored for the period of September 1996 to June 1997 based on daily OLR, NCEP/NCAR wind vector, and JTWC best track datasets. The MJO westerly wind burst associated with its eastward propagation can result in a series of tropical cyclogeneses in a multi-day interval. Only in the transition seasons are pairs of tropical cyclones observed in both the tropical sectors of the Indian-western Pacific Oceans. Two remarkable twin tropical cyclogeneses probably modulated by the MJO westerly wind burst are found: one is observed in the Indian Ocean in the middle of October 1996, and the other is observed in the Western Pacific Ocean in late May 1997. The twin tropical cyclogenesis in mid-October 1996 is observed when the super cloud cluster separates into two isolated clusters by the enhanced westerly wind, which is accompanied by two independent vortices in the equatorial tropical sectors. The other one, in late-May 1997, however, is characterized by one cyclonic flow that later results in another cyclonic cell in its opposite equatorial sector. Thus, there are two very important conditions for twin cyclogenesis: one is the MJO westerly wind straddling the equator, and the other is the integral super cloud cluster, which later splits into two cloud convective clusters with independent vortices.展开更多
The WMO/TCP and WWRP launched the North Western Pacific Tropical Cyclone Ensemble Forecast Project(NWP-TCEFP) in 2009 to explore the utility of ensemble forecasts, including multi-model ensemble forecasts of TCs, and ...The WMO/TCP and WWRP launched the North Western Pacific Tropical Cyclone Ensemble Forecast Project(NWP-TCEFP) in 2009 to explore the utility of ensemble forecasts, including multi-model ensemble forecasts of TCs, and to promote such products for operational TC forecasting. Operational global mediumrange ensembles, which have been exchanged in real-time in a CXML format under the initiative of the WMO GIFS-TIGGE Working Group, have been used to create ensemble products of TC tracks that were used by the Typhoon Committee Members and forecasters participating in the SWFDP in Southeast Asia through a password-protected website developed and maintained by the JMA. In some cases many or all of the ensembles have simultaneously predicted small or large ensemble spreads in TC tracks. The implication is that multi-model ensemble products provide forecasters with additional information on forecast certainty or uncertainty and thus increase the level of confidence in the forecasts. Another important outcome of the project was the responses to surveys conducted by the WMO/TCP and WWRP and also by the WMO GIFS-TIGGE Working Group. The responses confirmed that ESCAP/WMO Typhoon Committee Members have routinely accessed the website and have recognized the usefulness of the ensemble products available on the website for operational TC forecasting.展开更多
基金supported by the CATT,Japanthe Scientific Research Foundation for the R.eturned Overseas Chinese Scholars,State Ed-ucation MinistryLASG,Institute of Atmospheric Physics,Chinese Academy of Sciences.
文摘The modulation of twin tropical cyclogenesis in the Indian-western Pacific Oceans by the Madden-Julian Oscillation (MJO) during the onset period of 1997/98 ENSO is explored for the period of September 1996 to June 1997 based on daily OLR, NCEP/NCAR wind vector, and JTWC best track datasets. The MJO westerly wind burst associated with its eastward propagation can result in a series of tropical cyclogeneses in a multi-day interval. Only in the transition seasons are pairs of tropical cyclones observed in both the tropical sectors of the Indian-western Pacific Oceans. Two remarkable twin tropical cyclogeneses probably modulated by the MJO westerly wind burst are found: one is observed in the Indian Ocean in the middle of October 1996, and the other is observed in the Western Pacific Ocean in late May 1997. The twin tropical cyclogenesis in mid-October 1996 is observed when the super cloud cluster separates into two isolated clusters by the enhanced westerly wind, which is accompanied by two independent vortices in the equatorial tropical sectors. The other one, in late-May 1997, however, is characterized by one cyclonic flow that later results in another cyclonic cell in its opposite equatorial sector. Thus, there are two very important conditions for twin cyclogenesis: one is the MJO westerly wind straddling the equator, and the other is the integral super cloud cluster, which later splits into two cloud convective clusters with independent vortices.
文摘The WMO/TCP and WWRP launched the North Western Pacific Tropical Cyclone Ensemble Forecast Project(NWP-TCEFP) in 2009 to explore the utility of ensemble forecasts, including multi-model ensemble forecasts of TCs, and to promote such products for operational TC forecasting. Operational global mediumrange ensembles, which have been exchanged in real-time in a CXML format under the initiative of the WMO GIFS-TIGGE Working Group, have been used to create ensemble products of TC tracks that were used by the Typhoon Committee Members and forecasters participating in the SWFDP in Southeast Asia through a password-protected website developed and maintained by the JMA. In some cases many or all of the ensembles have simultaneously predicted small or large ensemble spreads in TC tracks. The implication is that multi-model ensemble products provide forecasters with additional information on forecast certainty or uncertainty and thus increase the level of confidence in the forecasts. Another important outcome of the project was the responses to surveys conducted by the WMO/TCP and WWRP and also by the WMO GIFS-TIGGE Working Group. The responses confirmed that ESCAP/WMO Typhoon Committee Members have routinely accessed the website and have recognized the usefulness of the ensemble products available on the website for operational TC forecasting.
