In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest adv...In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest advances in ISO theories with an emphasis particularly on theoretical paradigms involving nonlinear dynamics in the following aspects:(1) the basic ideas and limitations of the previous and current theories and hypotheses regarding the MJO,(2) the new multi-scale theory of the MJO based on the intraseasonal planetary equatorial synoptic dynamics (IPESD) framework,and (3) nonlinear dynamics of ISOs in the extratropics based on the resonant triads of Rossby-Haurwitz waves.展开更多
Thirty strong Madden–Julian Oscillation（MJO） events in boreal winter 1982–2001 are selected to investigate the triggering processes of MJO convection over the western equatorial Indian Ocean（IO）.These MJO events...Thirty strong Madden–Julian Oscillation（MJO） events in boreal winter 1982–2001 are selected to investigate the triggering processes of MJO convection over the western equatorial Indian Ocean（IO）.These MJO events are classified into three types,according to their dynamic and thermodynamic precursor signals in situ.In Type I,a remarkable increase in low-level moisture occurs,on average,7 days prior to the convection initiation.This low-level moistening is mainly due to the advection of the background mean moisture by easterly wind anomalies over the equatorial IO.In Type II,lower-tropospheric ascending motion anomalies develop,on average,4 days prior to the initiation.The cause of this ascending motion anomaly is attributed to the anomalous warm advection,set up by a suppressed MJO phase in the equatorial IO.In Type III,there are no clear dynamic and thermodynamic precursor signals in situ.The convection might be triggered by energy accumulation in the upper layer associated with Rossby wave activity fluxes originated from the midlatitudes.展开更多
With a hybrid atmosphere-ocean coupled model we carried out an experimental forecast of a well documented Madden-Julian Oscillation (MJO) event that was observed during the period of Tropical Ocean Global Atmosphere C...With a hybrid atmosphere-ocean coupled model we carried out an experimental forecast of a well documented Madden-Julian Oscillation (MJO) event that was observed during the period of Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA-COARE). The observed event, originated in the western Indian Ocean around 6 January 1993, moved eastward with a phase speed of about 6.2 m s 1 and reached the dateline around February 1. The hybrid coupled model reasonably forecasts the MJO initiation in the western Indian Ocean, but the predicted MJO event propagates too slow (～ 4.4 m s 1 ). Results from previous observational studies using unprecedented humidity profiles obtained by NASA Aqua/AIRS satellite suggested that two potential physical processes may be responsible for this model caveat. After improving the cumulus parameterization scheme based on the observations, the model is able to forecast the same event one month ahead. Further sensitivity experiment confirms that the speed-up of model MJO propagation is primarily due to the improved convective scheme. Further, air-sea coupling plays an important role in maintaining the intensity of the predicted MJO. The results here suggest that MJO prediction skill is sensitive to model cumulus parameterization and air-sea coupling.展开更多
From the view of system and structure, this paper studies the developing strategy of an industrial productive plan. It uses the method--system dynamics to establish a model of decision programme of the system. By usin...From the view of system and structure, this paper studies the developing strategy of an industrial productive plan. It uses the method--system dynamics to establish a model of decision programme of the system. By using this model, the paper studies the developing tendency of the industrial production in a city and gives the changing direction of economic indexes under various investment schemes. On methodology the paper integrates economic theory with quantitative and calculation techniques. Meanwhile, it also uses the software-- DYNAMO. With the real imitated operation on a computer satisfactory results are obtained.展开更多
An operational weather forecast model,coupled to an oceanic model,was used to predict the initiation and propagation of two major Madden–Julian Oscillation(MJO)events during the dynamics of the MJO(DYNAMO)campaign pe...An operational weather forecast model,coupled to an oceanic model,was used to predict the initiation and propagation of two major Madden–Julian Oscillation(MJO)events during the dynamics of the MJO(DYNAMO)campaign period.Two convective parameterization schemes were used to understand the sensitivity of the forecast to the model cumulus scheme.The first is the Tiedtke(TDK)scheme,and the second is the Simplified Arakawa–Schubert(SAS)scheme.The TDK scheme was able to forecast the MJO-1 and MJO-2 initiation at 15-and45-day lead,respectively,while the SAS scheme failed to predict the convection onset in the western equatorial Indian Ocean(WEIO).The diagnosis of the forecast results indicates that the successful prediction with the TDK scheme is attributed to the model capability to reproduce the observed intraseasonal outgoing longwave radiation–sea surface temperature(OLR–SST)relationship.On one hand,the SST anomaly(SSTA)over the WEIO was induced by surface heat flux anomalies associated with the preceding suppressed-phase MJO.The change of SSTA,in turn,caused boundary layer convergence and ascending motion,which further induced a positive column-integrated moist static energy(MSE)tendency,setting up a convectively unstable stratification for MJO initiation.The forecast with the SAS scheme failed to reproduce the observed OLR–SST–MSE relation.The propagation characteristics differed markedly between the two forecasts.Pronounced eastward phase propagation in the TDK scheme is attributed to a positive zonal gradient of the MSE tendency relative to the MJO center,similar to the observed,whereas a reversed gradient appeared in the forecast with the SAS scheme with dominant westward propagation.The difference is primarily attributed to anomalous vertical and horizontal MSE advection.展开更多
This study first investigates the effect of the Madden-Julian Oscillation(MJO)on the Northern Hemisphere(NH)mesosphere.Both observations and simulations suggest significant cooling in the NH polar mesosphere approxima...This study first investigates the effect of the Madden-Julian Oscillation(MJO)on the Northern Hemisphere(NH)mesosphere.Both observations and simulations suggest significant cooling in the NH polar mesosphere approximately 35 days after MJO phase 4(P4),which lags the MJO-induced perturbation in the upper stratosphere by 10 days.The enhanced planetary waves(PWs)propagate upward and result in wavenumber-1 pattern temperature anomalies in the mesosphere lagging MJO P4 by 25 days.The anomalous PWs also lead to the weaker eastward zonal wind in the upper stratosphere and lower mesosphere lagging MJO P4 by 30 days.Simultaneously,the weaker westerlies result in weaker climatological westward gravity waves(GWs)in the mesosphere due to critical-level filtering.The mesosphere meridional circulation is suppressed due to both anomalous PWs and GWs,and this suppression causes polar mesospheric cooling lagging MJO P4 by 35 days.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 40975028)
文摘In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest advances in ISO theories with an emphasis particularly on theoretical paradigms involving nonlinear dynamics in the following aspects:(1) the basic ideas and limitations of the previous and current theories and hypotheses regarding the MJO,(2) the new multi-scale theory of the MJO based on the intraseasonal planetary equatorial synoptic dynamics (IPESD) framework,and (3) nonlinear dynamics of ISOs in the extratropics based on the resonant triads of Rossby-Haurwitz waves.
基金supported by the China National 973 Project Grant No.2015CB453200)the National Natural Science Foundation of China Grant Nos.41475084 and 41230527+1 种基金the Office of Naval Research Grant No.N000141210450the International Pacific Research Center(IPRC) sponsored by the Japan Agency for Marine-Earth Science and Technology
文摘Thirty strong Madden–Julian Oscillation（MJO） events in boreal winter 1982–2001 are selected to investigate the triggering processes of MJO convection over the western equatorial Indian Ocean（IO）.These MJO events are classified into three types,according to their dynamic and thermodynamic precursor signals in situ.In Type I,a remarkable increase in low-level moisture occurs,on average,7 days prior to the convection initiation.This low-level moistening is mainly due to the advection of the background mean moisture by easterly wind anomalies over the equatorial IO.In Type II,lower-tropospheric ascending motion anomalies develop,on average,4 days prior to the initiation.The cause of this ascending motion anomaly is attributed to the anomalous warm advection,set up by a suppressed MJO phase in the equatorial IO.In Type III,there are no clear dynamic and thermodynamic precursor signals in situ.The convection might be triggered by energy accumulation in the upper layer associated with Rossby wave activity fluxes originated from the midlatitudes.
基金supported by NASA Earth Science Program, NSF Climate Dynamics Programthe Japan Agency for Marine-Earth Science and Technology (JAMSTEC), NASA+1 种基金NOAA through their sponsorship of the IPRCsupported by APEC Climate Center (APCC) as a part of APCC international research project
文摘With a hybrid atmosphere-ocean coupled model we carried out an experimental forecast of a well documented Madden-Julian Oscillation (MJO) event that was observed during the period of Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA-COARE). The observed event, originated in the western Indian Ocean around 6 January 1993, moved eastward with a phase speed of about 6.2 m s 1 and reached the dateline around February 1. The hybrid coupled model reasonably forecasts the MJO initiation in the western Indian Ocean, but the predicted MJO event propagates too slow (～ 4.4 m s 1 ). Results from previous observational studies using unprecedented humidity profiles obtained by NASA Aqua/AIRS satellite suggested that two potential physical processes may be responsible for this model caveat. After improving the cumulus parameterization scheme based on the observations, the model is able to forecast the same event one month ahead. Further sensitivity experiment confirms that the speed-up of model MJO propagation is primarily due to the improved convective scheme. Further, air-sea coupling plays an important role in maintaining the intensity of the predicted MJO. The results here suggest that MJO prediction skill is sensitive to model cumulus parameterization and air-sea coupling.
文摘From the view of system and structure, this paper studies the developing strategy of an industrial productive plan. It uses the method--system dynamics to establish a model of decision programme of the system. By using this model, the paper studies the developing tendency of the industrial production in a city and gives the changing direction of economic indexes under various investment schemes. On methodology the paper integrates economic theory with quantitative and calculation techniques. Meanwhile, it also uses the software-- DYNAMO. With the real imitated operation on a computer satisfactory results are obtained.
基金Supported by the NOAA of U.S.(NA18OAR4310298)National Natural Science Foundation of U.S.(AGS-1643297)National Natural Science Foundation of China(41875069).
文摘An operational weather forecast model,coupled to an oceanic model,was used to predict the initiation and propagation of two major Madden–Julian Oscillation(MJO)events during the dynamics of the MJO(DYNAMO)campaign period.Two convective parameterization schemes were used to understand the sensitivity of the forecast to the model cumulus scheme.The first is the Tiedtke(TDK)scheme,and the second is the Simplified Arakawa–Schubert(SAS)scheme.The TDK scheme was able to forecast the MJO-1 and MJO-2 initiation at 15-and45-day lead,respectively,while the SAS scheme failed to predict the convection onset in the western equatorial Indian Ocean(WEIO).The diagnosis of the forecast results indicates that the successful prediction with the TDK scheme is attributed to the model capability to reproduce the observed intraseasonal outgoing longwave radiation–sea surface temperature(OLR–SST)relationship.On one hand,the SST anomaly(SSTA)over the WEIO was induced by surface heat flux anomalies associated with the preceding suppressed-phase MJO.The change of SSTA,in turn,caused boundary layer convergence and ascending motion,which further induced a positive column-integrated moist static energy(MSE)tendency,setting up a convectively unstable stratification for MJO initiation.The forecast with the SAS scheme failed to reproduce the observed OLR–SST–MSE relation.The propagation characteristics differed markedly between the two forecasts.Pronounced eastward phase propagation in the TDK scheme is attributed to a positive zonal gradient of the MSE tendency relative to the MJO center,similar to the observed,whereas a reversed gradient appeared in the forecast with the SAS scheme with dominant westward propagation.The difference is primarily attributed to anomalous vertical and horizontal MSE advection.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB 41000000)the National Natural Science Foundation of China(Grant Nos.41874180,41974175,41831071,and 41874181)the Open Research Project of Large Research Infrastructures of CAS—“Study on the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”.
文摘This study first investigates the effect of the Madden-Julian Oscillation(MJO)on the Northern Hemisphere(NH)mesosphere.Both observations and simulations suggest significant cooling in the NH polar mesosphere approximately 35 days after MJO phase 4(P4),which lags the MJO-induced perturbation in the upper stratosphere by 10 days.The enhanced planetary waves(PWs)propagate upward and result in wavenumber-1 pattern temperature anomalies in the mesosphere lagging MJO P4 by 25 days.The anomalous PWs also lead to the weaker eastward zonal wind in the upper stratosphere and lower mesosphere lagging MJO P4 by 30 days.Simultaneously,the weaker westerlies result in weaker climatological westward gravity waves(GWs)in the mesosphere due to critical-level filtering.The mesosphere meridional circulation is suppressed due to both anomalous PWs and GWs,and this suppression causes polar mesospheric cooling lagging MJO P4 by 35 days.
