By comparing with ENSO events that ever happened in the history, the basic features and probable causes of the anomalous sea surface temperature of the tropical Pacific Ocean during 1997 and 1998 have been analyzed di...By comparing with ENSO events that ever happened in the history, the basic features and probable causes of the anomalous sea surface temperature of the tropical Pacific Ocean during 1997 and 1998 have been analyzed diagnostically. It is found that the 1997/1998 El Nino had significant abnormalities and peculiarities. It differs from the previous El Ni駉 events falling into the simple eastern pattern or western pattern. The predictions of 1997/1998 El Ni駉 event have also been tested with an intermediate ocean-atmosphere coupled dynamic model. The results show that the skills of the 0～24 lead month forecasts for the warm event are all above 0.5. The predictions of the mature phase and the later stages of the warm event are better than those of the beginning phase.展开更多
Clear air turbulence(CAT),a meso-or microscale(subgrid scale)phenomenon occurring in synoptic scale flow field at high altitude,is very difficult to be observed by the conventional obser- vation network.Thus it is nec...Clear air turbulence(CAT),a meso-or microscale(subgrid scale)phenomenon occurring in synoptic scale flow field at high altitude,is very difficult to be observed by the conventional obser- vation network.Thus it is necessary to approach an index to predict CAT.But at first,the struc- ture characteristics of CAT should be preanalyzed.In this paper,based on the theoretical and diag- nostic analysis of a case,features for wind profile,energy budget and dynamic mechanism of this case were presented.Furthermore,an objective and quantitative index for CAT forecast was giv- en.The verification for its efficiency was done with both real-time observation data and products from a numerical model.The results are very encouraging.展开更多
By using the routine weather data and the numerical value forecast products,applying the weather analysis and diagnostic analysis methods,the cold wave weather which happened in the south area of Dalian was analyzed o...By using the routine weather data and the numerical value forecast products,applying the weather analysis and diagnostic analysis methods,the cold wave weather which happened in the south area of Dalian was analyzed on December 29-30,2009.The results showed that based on the temperature rise in prior period,the strong cold air accumulated in Mongolia and passed Ulan Bator,Erenhot to invade Dalian area.In the cold wave process,the circulation situations in the middle and high latitudes were the 'one ridge and one trough' pattern in Asia.The dynamic mechanisms were the rotary low-pressure trough in high altitude and the strong frontal zone,and the flow field which induced the cold wave to break out was the 'low trough rotation pattern'.After the cold air broke out,Dalian area was controlled by the strong cold advection.The cold high-pressure on the ground entered into the key zone and reached the intensity of cold wave.However,the circulation of cold wave occurrence was southerly,and the shifts of cold air and influence system were quicker.Therefore,the cold wave appeared in Dalian's south areas which included Lvshun,Dalian and Jinzhou.On this basis,the key point of cold wave weather forecast in Dalian area was summarized.展开更多
基金Key project of China Meteorological Administration "Studies on the cause of formation and the application of prediction for the heavy rainstorms over Yangtze River and Nenjiang River Basins in 1998" and the sub-project II (96-908-02-05) of National Key
文摘By comparing with ENSO events that ever happened in the history, the basic features and probable causes of the anomalous sea surface temperature of the tropical Pacific Ocean during 1997 and 1998 have been analyzed diagnostically. It is found that the 1997/1998 El Nino had significant abnormalities and peculiarities. It differs from the previous El Ni駉 events falling into the simple eastern pattern or western pattern. The predictions of 1997/1998 El Ni駉 event have also been tested with an intermediate ocean-atmosphere coupled dynamic model. The results show that the skills of the 0～24 lead month forecasts for the warm event are all above 0.5. The predictions of the mature phase and the later stages of the warm event are better than those of the beginning phase.
文摘Clear air turbulence(CAT),a meso-or microscale(subgrid scale)phenomenon occurring in synoptic scale flow field at high altitude,is very difficult to be observed by the conventional obser- vation network.Thus it is necessary to approach an index to predict CAT.But at first,the struc- ture characteristics of CAT should be preanalyzed.In this paper,based on the theoretical and diag- nostic analysis of a case,features for wind profile,energy budget and dynamic mechanism of this case were presented.Furthermore,an objective and quantitative index for CAT forecast was giv- en.The verification for its efficiency was done with both real-time observation data and products from a numerical model.The results are very encouraging.
文摘By using the routine weather data and the numerical value forecast products,applying the weather analysis and diagnostic analysis methods,the cold wave weather which happened in the south area of Dalian was analyzed on December 29-30,2009.The results showed that based on the temperature rise in prior period,the strong cold air accumulated in Mongolia and passed Ulan Bator,Erenhot to invade Dalian area.In the cold wave process,the circulation situations in the middle and high latitudes were the 'one ridge and one trough' pattern in Asia.The dynamic mechanisms were the rotary low-pressure trough in high altitude and the strong frontal zone,and the flow field which induced the cold wave to break out was the 'low trough rotation pattern'.After the cold air broke out,Dalian area was controlled by the strong cold advection.The cold high-pressure on the ground entered into the key zone and reached the intensity of cold wave.However,the circulation of cold wave occurrence was southerly,and the shifts of cold air and influence system were quicker.Therefore,the cold wave appeared in Dalian's south areas which included Lvshun,Dalian and Jinzhou.On this basis,the key point of cold wave weather forecast in Dalian area was summarized.
