Facing significant effects of the Tibetan plateau and many other steep mountains on weather and climate, especially on the precipitation in China, a Advanced Regional Eta-coordinate numerical weather prediction Model (AREM) has been developed since 1980s by well handling with topography together with self-developed water vapor advection scheme. The AREM has shown its great capabilities in capturing major features of precipitation in the Eastern China, including the distribution of summer rain belt, heavy rainfall intensity and maximum rainfall locations. The CREM, a regional climate mode developed from the AREM, has also shown good performance in simulating rainfall and temperature in Eastern China, particularly in regions along the Yangtze River.
The AREM has been widely applied in many research institutes and operational centers in meteorological, hydrological, environmental and military sectors in China. Hundreds of peer-reviewed journal articles have been published by numerical simulation using the AREM. More than twenty masters and doctors completed their dissertations for academic degree based on AREM. So far, various versions of the AREM have been applied to scientific research and operational prediction relating to meteorology, hydrology and military.
- 宇如聪, 薛纪善, 徐幼平, AREMS中尺度暴雨数值预报模式系统, 2004年11月, 气象出版社(书).
- Shi, Hongbo, Rucong Yu (Corresponding author), Jian Li and Tianjun Zhou, 2009, Development of a Regional Climate Model (CREM) and Evaluation on Its Simulation of Summer Climate over Eastern China, Journal of the Meteorological Society of Japan, Vol. 87, No.3, 381-401. [Link]
- Yu Rucong, Xu Youping, 2004, AREM and its simulations on the daily rainfall in summer in 2003, Acta Meteorlogica China, 62(6), 718-724.
- Yu, Rucong, 1994, A Two-Step Shape-Preserving Advection Scheme, Advances in Atmospheric Sciences, Vol.11, No.4, 479-490.
- Yu Rucong, Zeng Qingcun, Peng Guikang, and Chai Fuxin, 1994, Research on "Ya-An-Tian-Lou" Part II: Numerical Trial-Forecasting, Chinese Journal of Atmospheric Sciences, 18(5): 535-551.
- Yu Rucong, 1994, Properties of the spatial finite-difference scheme based on the E-grid, Chinese Journal of Atmospheric Sciences, 18(2): 152-162.
- Yu, Rucong, 1989, Design of Limited Area Numerical Weather Prediction Model with Steep Mountains, Chinese Journal of Atmospheric Sciences, 13(2), 139-149.
An air-sea coupling scheme, which has been designed to give effective control over the climate drift, had gone a long way in the establishment of the first global Air-Sea coupling model in China. A regional ocean - sea ice coupling model in Arctic Pole regarding oceanic circumfluence and ice-sea interaction has also been established. With the team efforts, a direct land-air-sea-ice coupling climate system model took its shape, which was modularized on the basis of coupling framework but without flux correction. Together with model research team, systematic analysis and evaluation on the simulation of coupling mode system and its sub-schemes over the current climate and the climate in East Asia in particular were carried out, including evaluating the simulation performance of the model in rainfall behaviors over Eastern Asian, in the formation of Subtropical High, in the climate effect of Western Pacific Warm Pool and the Eastern Pacific Cold Tongue and stratus, and in the seasonal variations and other aspects. The results make us aware of the main shortcomings in current climate model and help us to further improve and develop our climate system model.
- Zhou, Tianjun and Rucong Yu, 2006, Twentieth-Century Surface Air Temperature over China and the Globe Simulated by Coupled Climate Models, Jounral of Climate, Vol. 19, 5843-5858.
- Dai, Fushan, Rucong Yu, Xuehong Zhang, Yongqiang Yu and Jianglong Li, 2005, Impacts of an Improved Low-Level Cloud Scheme on the Eastern Pacific ITCZ-Cold Tongue Complex, Advances in Atmospheric Sciences. Vol.22, 559-574.
- Yu, Yongqiang, Rucong Yu, Xuehong Zhang and Hailong Liu, 2002, A Flexible Coupled Ocean-Atmosphere General Circulation Model, Advances in Atmospheric Sciences, Vol. 19, 169-190.
- Li, Wei, Rucong Yu, Hailong Liu and Yongqiang Yu, 2001, Impacts of Diurnal Cycle of SST on the Intraseasonal Variation of Surface Heat Flux over the Western Pacific Warm Pool, Advances in Atmospheric Sciences, Vol.18, 793-806.
- Yu, Rucong, Wei Li, Xuehong Zhang, Yimin Liu, Yongqiang Yu, Hailong Liu and Tianjun Zhou, 2000,Climatic Features related to Eastern China Summer Rainfalls in the NCAR CCM3. Advances in Atmospheric Sciences, Vol.17, No.4, 503-518.
- Yu, Rucong, Xiangze Jin and Xuehong Zhang, 1995, Design and Numerical Simulation of An Arctic Ocean Circulation and Thermodynamic Sea-Ice Model, Advances in Atmospheric Sciences, Vol.12, No.3, 289-310.
- Zhang, Xuehong, Ning Bao, Rucong Yu and Wang Wanqu, 1992, Coupling Scheme Experiments Based on an Atmospheric and Oceanic GCM, Chinese Journal of Atmospheric Sciences (In English), Vol.16, No.2.
3. Presenting the unique mid-level stratus distribution and its cloud radiative forcing characteristics and revealing the cloud - climate feedback processes along the upper valley of Yangtze River
Evidence is presented to show that the largest amount of mid-level stratus, especially the nimbostratus and altostratus, and the maximum annual mean cloud optical depth are located on the lee side of the Tibetan Plateau. These stratus clouds produce extremely strong cloud radiative forcing at the top of the atmosphere, which fundamentally inﬂuences on the local energy balance and climate change. The anomalous cloudiness and surface temperature vary in tandem. The evidence suggests a positive feedback between the continental stratus clouds and surface temperature through changing lower-tropospheric relative humidity and stratiﬁcation. It is suggested that the positive climate feedback of the continental stratus cloud may be instrumental in understanding the long-term climatic trend and variations over East Asia.
By comparing the seasonal variations of the clouds in the eastern China and Indian region, it has been found that they are markedly different from each other, though both of them are among the Asia monsoon regions and their largest precipitation rates arise in summer. In Indian monsoon region, the precipitation and total cloud cover, even its high, middle or low cloud cover, all reaches their peak in summer. In eastern China, however, its maximum happens in spring and mainly benefits from the mid- and lower- stratiform cloud.
- Yu, Rucong, Bin Wang and Zhou Tianjun, 2004, Climate effects of the deep continental stratus clouds generated by the Tibetan Plateau. J. Climate. Vol.17, No.13, 2702-2713.
- Li, Jian, Rucong Yu (Corresponding author), Tianjun Zhou and Bin Wang, 2005, Why is there an early spring cooling trend downstream of the Tibetan Plateau? Journal of Climate, Vol. 18, No. 22, 4660-4668.
- Li, Yunying，Rucong Yu (Corresponding author) and Youping Xu, 2005, AREM Simulations of Cloud Features over Eastern China in February 2001. Advances in Atmospheric Sciences. Vol.22(2), 260-270.
- Li, Yunying, Rucong Yu, Youping Xu and Xuehong Zhang, 2004, Spatial Distribution and Seasonal Variation of Cloud over China Based on ISCCP Data and Surface Observations, Journal of the Meteorological Society of Japan, Vol.82, No.2, pp.761-773.
- Yu, Rucong, Yongqiang Yu and Minghua Zhang, 2001, Comparing Cloud Radiative properties between the Eastern China and the Indian Monsoon Region. Advances in Atmospheric Sciences, Vol.18, No.6, 1090-1102.
4. Exploring the three-dimensional structure of inter-decadal climate change in eastern China
Eastern Asian climate has experienced a decadal scale shift by the end of 1970s. By thoroughly analyses and studies, a relatively comprehensive description of the three-dimensional structure of the inter-decadal climate variations has been presented in eastern China. The three-dimensional structure directly links to the temperature changes in the upper-middle troposphere and shows distinct inter-seasonal variation. The cooling in upper and middle troposphere results in the arising of anomalous cyclonic circulation in the upper levels where the westerly jet south of the East Asian grows stronger. At the same time, the lower level takes on an anomalous anti-cyclonic circulation, which weakens the summer monsoon. The intensified upper level westerly jet changes the intensity of divergence in the upper and middle troposphere, and triggers a unique cloud-radiation feedback process which plays a significant role in the surface cooling in the downstream Tibetan Plateau. The joint impact of the southward westerly jet in the upper level and the decreased summer monsoon in the lower level ultimately leads to the “southern-flooding and northern-drought” rain anomaly pattern in eastern China. A physically conceptual model has been raised accordingly that the inter-decadal air temperature changes and the “Southern-flooding and Northern-drought” rainfall pattern are subjected to the cooling of the upper troposphere in East Asia. Both of the position and intensity of the cold center in the upper troposphere change remarkably among seasons. In spring, the cold center moves southward, resulting in severe drought in South China during this season in recent years. In summer, the cold center locates around 40N, which brings about a rain belt anomaly of “Southern-flooding and Northern-drought” in eastern China. The results provide direct observational basis for evaluating the performance of atmospheric circulation model and air-sea coupling model and for verifying the roles of different forcing factors in inter-decadal climate variations in East Asia.
- Yu, Rucong, Zhou Tianjun, Li Jian and Xin Xiaoge, 2008, Progress in the studies of three-dimensional structure of interdecadal climte change over eastern China, Chinese Journal of Atmospheric Sciences, 32(4): 893-905.
- Yu, Rucong and Zhou Tianjun, 2007, Seasonality and three-dimensional structure of the interdecadal change in East Asian monsoon, J. Climate, Vol. 20, 5344-5355.
- Xin, Xiaoge, Yu Rucong (Corresponding author), Zhou Tianjun, and Bin Wang, 2006, Droughty Late Spring of South China in Recent Decades. Journal of Climate. Vol. 19, 3197-3206.
- Xin, Xiaoge, Zhaoxin Li, Rucong Yu and Tianjun Zhou, 2008, Impacts of upper tropospheric cooling upon the late spring drought in East Asia simulated by a regional climate model, Advances in Atmospheric Sciences. Vol.25(4), 555-562.
- Li Jian, Yu Rucong (Corresponding author), Zhou Tianjun and Bin Wang, 2005, Why is there an early spring cooling trend downstream of the Tibetan Plateau? Journal of Climate, Vol. 18, No. 22, 4660-4668.
- Yu, Rucong, B. Wang, and Zhou Tianjun, 2004, Tropospheric cooling and summer monsoon weakening trend over East Asia. Geophysical Research Letters, Vol. 31, L22212, doi:10.1029/2004GL021270.
5. Disclosing the relations between atmospheric circulation anomaly that affects inter-decadal climate variations in Eastern China and mid- and high- latitude circulation anomaly relating to NAO
The NAO index series in winter show opposite phase with the average temperature series in the subtropical regions in Eurasia continent. When the winter NAO presents in positive phase, the cooling in subtropical regions in Eurasia takes on the quasi-barotropic eastward propagation. Such cooling is strongest in the upper and middle troposphere and its cooling signal maintains stable after arriving at east of Tibetan Plateau. The corresponding circulation variations in this course make an impact on the changes of cloud, precipitation and temperature in eastern China.
A teleconnection pattern NAULEA, linking the climate change in North Atlantic and Eurasia, has been brought forward accordingly. The NAULEA have five centers, extends from the North Atlantic to northwestern Europe, and then stretches eastward the Urals, with its eastern end over North China. When the NAULEA is in positive phase, North Atlantic exhibits the feature of NAO positive phase while the surface temperature from the Ural regions to the upper troposphere is extremely warmer and dominated by the anomalous high pressure. The mid- and upper troposphere in the northern China is an anomalous cold center and anomalous cyclonic circulation, which play a role in the variation of cloud, rain and temperature in North China. It has been shown hereby that the unique climate changes in China closely relates to the atmospheric circulation variation related to the anomalous global climate, instead of being simply accounted for the leading forcing resulted from local pollution.
- Li, Jian, Rucong Yu (Corresponding author) and Tianjun Zhou, 2008, Teleconnection between NAO and climate downstream of the Tibetan Plateau, J. Climate, Vol.21, No.18, 4680-4690.
- Yu, Rucong and Zhou Tianjun, 2004, Impacts of Winter-NAO on March Cooling Trends over Subtropical Eurasia Continent in the Recent Half Century. Geophysical Research Letters, Vol. 31, No.12, L12204, doi:10.1029/2004GL019814, 2004.
6. Understanding on the regional features of diurnal rainfall variation in China
It has been pointed out that diurnal variation of summer precipitation in China show remarkable regional features. The rainfall mainly peaks in late afternoon in southern and northeastern China, mostly in midnight in the Tibetan Plateau and its east flank and in early morning in the upper and middle reaches of the Yangtze River. The summer rainfall shows two comparable peaks, with one in the early morning and the other in the late afternoon, in regions between the Yangtze River and Yellow River. The relationship between the rainfall diurnal phase and duration in eastern China is revealed. The long-duration rainfall events mainly reach the maxima at night or in the early morning, while the short-duration rainfall events mainly peak in afternoon or evening. The diurnal precipitation variation in the southwest and southeast of China show different features in climate mean state and seasonal variation. Based on TRMM data, the regional differences between the convective and stratiform precipitation in terms of diurnal variation of both surface precipitation rate and precipitation profile in South China is analyzed. As for the stratiform precipitation, the peak of precipitation rate and profile mostly arise at evening in the southeast, while they reach the maxima between midnight and dawn in the southwest. In most areas of South China, the convective precipitation rate and profile peak in the evening, while in the Sichuan basin which is closely neighboring the east of Tibetan Plateau, the maxima happen between midnight and dawn, with the peak time of precipitation rate of convective precipitation coming roughly 4 hours ahead of that of stratiform precipitation. In addition, we have also systematically analyzed the regional characteristics of diurnal surface wind cycle in China, and pointed out that diurnal wind field variation in the lower troposphere indicated by the mountain stations contributes greatly to the eastward-delayed phase distribution of diurnal precipitation variation along the Yangtze River valley.
- Chen, Haoming, Rucong Yu, Jian Li, Weihua Yuan and Tianjun Zhou, 2010, Why Nocturnal Long-Duration Rainfall Presents an Eastward-Delayed Diurnal Phase of Rainfall down the Yangtze River Valley, Journal of Climate, Vol. 23, 905-917.
- Yu, Rucong, Weihua Yuan, Jian Li and Yunfei Fu, 2009, Diurnal phase of late-night against late-afternoon of stratiform and convective precipitation in summer southern contiguous China, Climate Dynamics, DOI 10.1007/s00382-009-0568-x
- Yu, Rucong, Jian Li and Haoming Chen, 2009, Diurnal variation of surface wind over central eastern China, Climate Dynamics, Vol. 33, DOI 10.1007/s00382-008-0478-3, 1089-1097.
- Li, Jian, Rucong Yu and Tianjun Zhou, 2008, Seasonal variation of the diurnal cycle of rainfall in the southern contiguous China, J. Climate, Vol. 21, No. 22, 6036–6043.
- Yu, Rucong, Youping Xu, Tianjun Zhou and Jian Li，2007, Relation between rainfall duration and diurnal variation in the warm season precipitation over central eastern China, Geophysical Research Letters, Vol. 34, L13703, doi: 10.1029/2007GL030315
- Yu, Rucong, Tianjun Zhou, Anyuan Xiong, Yanjun Zhu and Jiming Li, 2007, Diurnal variations of summer precipitation over contiguous China, Geophysical Research Letters, Vol. 34, L01704, doi: 10.1029/2006GL028129.
- Li Yunying , Yu Rucong, Xu Youping, Zhang Xuehong, 2003, The formation and diurnal changes of stratiform clouds in southern China, Acta Meteorologica Sinica, 61(6): 733-743.