CAS Strategic Priority Programme (B) Newsletter July 2014 Content Research Progress (Ⅱ) Three modes of the precipitation stable isotopes over the Tibetan Plateau revealing the interaction between the westerlies and the Indian monsoon. Diverse responses of green up date to climate change over the past decade on the Tibetan Plateau. The alpine grassland NPP (Net Primary Productivity) over the Qinghai Tibet plateau increased in recent thirty years Scientific Activities CAS Center for Excellence Tibetan Plateau Earth Science was set up at ITP. Photo by Wang Yongjie, 2012 Contact Information Address: 16 Lincui Road, Chaoyang District, Beijing 100101, China Phone: 010 84097103 Fax: 010 84097041 Email: stp b@itpcas.ac.cn Website: stpb.itpcas.ac.cn Research Progress (Ⅱ) Three modes of the precipitation stable isotopes over the Tibetan Plateau revealing the interaction between the westerlies and the Indian monsoon By Gao Jing The influences of the westerlies and Indian monsoon are critical for advection of heat and moisture, and climate patterns in the Tibetan Plateau. Understanding the influence of the westerlies and Indian monsoon on the moisture transport processes over the Tibetan Plateau is a key point to reveal the spatial variations of the glaciers, lakes and rivers in this region, and has crucial implications for the interpretation of paleo climate and paleo environment records over the Tibetan Plateau. Based on systematic precipitation stable isotopes observation at stations and corresponding meteorological data (temperature, precipitation amount and winds) analysis, combined with isotopic general circulation models, we illuminate the climate controls of precipitation stable isotopes over the Tibetan Plateau, and clarify the influence of different efforts (temperature effort, amount effort and altitude effort) on precipitation stable isotopes. Finally, we reveal the mechanism of the precipitation stable isotopes variations over the Tibetan Plateau beyond the interaction of the westerlies and Indian monsoon. Based on precipitation isotopic composition at more than 20 stations in the Tibetan Plateau (TP) located at the convergence of air masses between the westerlies and monsoon (Fig. 1), we establish a database of precipitation δ 18 O and use different models to evaluate the climatic controls of precipitation δ 18 O over the TP. The spatial and temporal patterns of precipitation δ 18 O and their relationships with temperature and precipitation reveal three distinct domains (Fig. 2), respectively associated with the influence of the westerlies (Northern TP), Indian monsoon (Southern TP) and transition in between. Precipitation δ 18 O in the monsoon domain experiences an abrupt decrease in May and most depletion in August, attributable to the shifting moisture origin between Bay of Bengal (BOB) and southern Indian Ocean. High resolution atmospheric models capture the spatial and temporal patterns of precipitation δ 18 O and their relationships with
moisture transport from the westerlies and Indian monsoon. In the westerlies domain, atmospheric models ideally represent the relationships between climate and precipitation δ 18 O. More significant temperature effect exists when either the westerlies or Indian monsoon is the sole dominant atmospheric process. The observed and simulated altitude δ 18 O relationships strongly depend on the season and the domain (monsoon or westerlies). Our results also demonstrate the good performances of models in the large scale distribution of precipitation stable isotopes and moisture transport over the Tibetan Plateau. Parts of the results have been published in Yao et al, 2013, Reviews of Geophysics; Gao et al, 2013, Tellus; and Gao et al, 2014, Journal of climate. Fig. 1. General patterns of moisture transport under the influences of the westerlies and Indian monsoon over the TP. Red triangles depict locations of δ 18 O monitoring stations: 1 Urumqi, 2 Zhangye, 3 Taxkorgen, 4 Delingha, 5 Hetian, 6 Lanzhou, 7 Kabul, 8 Tuotuohe, 9 Yushu, 10 Shiquanhe, 11 Gaize, 12 Nagqu, 13 Yangcun, 14 Bomi, 15 Lulang, 16 Lhasa, 17 Nuxia, 18 Baidi, 19 Larzi, 20 Wengguo, 21 Dingri, 22 Dui, 23 Nyalam, 24 Zhangmu; open circles show ice core sites: a Muztagata, b Dunde, c Malan, d Guliya, e Puruogangri, f Galadaindong, g Tanggula 1, h Tanggula 2, i Zuoqiupu, j Dasuopu, k East Rongbuk. Up triangles stand for GNIP stations, and down triangles stand for TNIP stations. Fig. 2. Seasonal patterns of observed precipitation δ 18 O, precipitation amount (P) and temperature (T) in different TP domains. (a) Monthly weighted δ 18 O ( ), (b) precipitation amount (mm/month) and (c) temperature averages ( C) in the westerlies domain (7 stations, left panel). (d), (e) and (f) same as (a), (b) and (c), but for the transition domain (4 stations, middle). (g), (h) and (i) same as (a), (b) and (c), but for the monsoon domain (13 stations, right).
Reference Yao, T., V. Masson Delmotte, J. Gao, W. Yu, X. Yang C. Risi, C. Sturm, M. Werner, H. Zhao, Y. He, W. Ren, L. Tian, C. Shi, S. Hou, 2013, A review of climatic controls on δ 18 O in precipitation over the Tibetan Plateau: Observations and simulations, Rev. Geophys., 51: 525 548. Gao, J., V. Masson Delmotte, T. Yao, L. Tian, C. Risi, and G. Hoffmann, 2011. Precipitation water stable isotopes in the south Tibetan Plateau: Observations and modeling, J. Clim., 24: 3161 3178, Gao J., V. Masson Delmotte, C. Risi, Y. He, T. Yao, 2013. What controls precipitation δ 18 O in the southern Tibetan Plateau at seasonal and intra seasonal scales? A case study at Lhasa and Nyalam. Tellus B 2013, 65: http://dx.doi.org/10.3402/ tellusb.v65i0.21043 Diverse responses of green up date to climate change over the past decade on the Tibetan Plateau By Shen Miaogen Numerous studies shown that spring phenology of plants in cold regions is sensitive to climate change. The spring warming during the past few decades has induced substantial advance of vegetation green up date at the high latitudes and altitudes. As the largest and highest plateau on Earth, the Tibetan Plateau (TP) is widely recognized a sensitive area in the global change, but received less attention than the Arctic region. Information of the vegetation spring phenological changes provides insight into the TP response to climate change and is also important for the traditional nomadic lifestyle. However, despite the intensive spring warming over the past decade, strongly contradictory evidences exist regarding changes in the green up date, mainly due to the contaminations of snow cover on the data used. We assess temporal changes of green up date during the period 2000 2011 by using four greenness vegetation indices from different satellite sensors and five different methods for each of the four indices which are firstly calibrated for adverse effects of snow/ice cover and clouds. We further examine how the spatial pattern of the phenological changes is associated with the changes in climatic components. The green up date viewed at the regional scale showed neither a significant advance nor delay despite the significant increase in spring temperature by 0.10 C yr 1 (Fig. 1), indicating that climatic warming does not necessarily lead to spring phenological advance on TP. This insignificance resulted from the substantial spatial heterogeneity of trends in green up date, with a notably delay in the southwest region (Fig. 2). These changes doubled the altitudinal gradient of green up date, from 0.63 days/100m in the early 2000s to 1.30 days/100m in the early 2010s. Green-up date (Julian day) 165 160 155 150 2000 2002 2004 2006 2008 2010 Fig.1. Inter annual changes in green up date spring temperature from 2000 to 2011 Fig.2. Spatial pattern of temporal trend in the green up date from 2000 to 2011 9 8 7 6 Spring temperature ( )
Fig. 3. Spatial pattern of temporal trends in spring temperature and precipitation over 2000 2011. The delays in the southwest region and at high altitudes were likely caused by the decline in spring precipitation, rather than the increasing spring temperature, and the advance in the northeastern TP by the increased temperature and precipitation (Fig. 3). Hence, spring precipitation may be an important regulator of spring phenological responses to climatic warming over a considerable area of the plateau. The diverse phenological responses to climate change across the TP indicate that more mechanical studies are needed, which can begin with more in situ meteorological and phenological observations and manipulative experiments as well as developing phenology models. Parts of the results have been published in Shen et al, 2013, PNAS and Shen et al, 2014, Agriculture and Forest Meteorology. Reference Shen M, Sun Z, Wang S, Zhang G, Kong W, Chen A, Piao S, 2013. No evidence of continuously advanced green up dates in the Tibetan Plateau over the last decade. Proceedings of the National Academy of Sciences of the United States of America, 110: E2329. Shen M, Zhang G, Cong N, Wang S, Kong W, Piao S, 2014. Increasing altitudinal gradient of spring vegetation phenology during the last decade on the Qinghai Tibetan Plateau. Agricultural and Forest Meteorology 189 190: 71 80.
The alpine grassland NPP (Net Primary Productivity) over the Qinghai Tibet plateau increased in recent thirty years (1982 2011) By Zhang Xianzhou Both global climate change and anthropogenic activities are the main driving forces of terrestrial ecosystems. Due to its high elevation, frigid and aridity, the Tibetan plateau (TP) is more sensitive to the climate change and anthropogenic activities. The dominant alpine grassland vegetation over the TP has changed much more as the increased disturbances of climate change and anthropogenic activities. In the past several decades, how the alpine vegetation changed, what the driving forces were and whether the grassland ecosystem changes caused by climate change or anthropogenic activities are still questions to be answered. Especially it is the key bottle neck question about the alpine ecosystem change for how to identify and quantify the impacts from the climate change and anthropogenic activities on alpine grassland over the TP. Replying these questions are not only helpful for deep understanding about the high plateau ecology research, but also can providing scientific bases for evaluating the large scale ecological protection projects and optimizing the plateau ecosystem management. We use the combined methods of field observation, remote sensing and model simulation to reconstruct the last thirty year alpine grassland NPP spatio temporal change over the TP. Using a climate factor driven model to simulate grassland potential NPP P and a remote sensing model to simulate the actual NPP A, which is affected by both of climate change and human activities, so the human induced NPP H is modelled as the difference of potential and actual NPP. For comparing the trend of the potential and human induced NPP over periods, the main driving force to ecosystem change can be determined. Fig. 1. Inter annual variation in anomalies of alpine grasslands NPP A, NPP P, and NPP H over the TP from 1982 to 2011. Under the influences of climate change and human activities, the alpine grassland NPP A increased about 19.9% over the TP in the past thirty years from 1982 to 2011 (Fig.1). Although, the simulation results also showed that the prime determinants of the increase in NPP A in the two periods were changed, the climate change and anthropogenic activities mainly drove the actual grassland NPP increasing in the first 20 year and the last 10 year respectively. A warm wet climate and less human activities caused a rapid increase in NPP P and a relatively slow increase in NPP H, which led to an NPP A increase of 16.8% from 1982 to 2001. However, as the warm dry
climate decreased the alpine grassland NPP P over the TP from 2001 to 2011, marked human intervention (Grazing Withdrawal Program and Ecological Compensation) on the alpine grassland ecosystem played a much more important role in the grassland restoration, which still resulted in NPP A increasing of 8.1% in this period (Fig. 2). The climate change dominated the alpine grassland NPP change over the most area of the TP, but area percentage of NPP decreased by the anthropogenic activities is less than 5%. Parts of the results have been published in Chen et al, 2014, AFM. Fig. 2. Spatial distribution of different causes for alpine grassland NPP change in the periods 1982 2001 (a) and 2001 2011 (b). Note: NC is NPP A had no change; ICC is NPP A increased due to climate change; IHA is NPP A increased due to human activities; DCC is NPP A decreased due to climate change and DHA is NPPA decreased due to human activities. Reference Chen B, Zhang X, Tao J, Wu J, Wang J, Shi P, Zhang Y, Yu C, 2014. The impact of climate change and anthropogenic activities on alpine grassland over the Qinghai Tibet Plateau. Agricultural and Forest Meteorology, 189 190: 11 18.
Scientific Activities CAS Center for Excellence Tibetan Plateau Earth Science was set up at ITP CAS Center for Excellence Tibetan Plateau Earth Science was established in the Institute of Tibetan Plateau Research, Chinese Academy of sciences (CAS) in January 21, 2014,. The ceremony was host by Prof. Xu Ruiming, the director of the Bureau of Frontier Sciences and Education, CAS. Prof. Ding Zhongli, the vice president of CAS, inaugurated for the new center. Prof. Yao Tandong, The director of Institute of Tibetan Plateau Research, CAS, presented the mission, organization, and management of the center. The heads from Bureau of Frontier Sciences and Education, Bureau of Development & Planning, Bureau of Facility Support and Budget, and Bureau of Personnel, CAS, as well as the associated member institutes of the center attended the ceremony. CAS Center for Excellence Tibetan Plateau Earth Science mainly based on the CAS Strategic Priority Programme (B) Tibetan Multiple Spheres Interactions and Their Resource Environment Significance (TIMI), will aim to gather talents and the most innovative researchers, construct a world level platform for the research on Tibetan Plateau, manage domestic and international research programs, build a new innovative, open, competitive and flexible environment. The center will be established relaying on the Institute of Tibetan Plateau Research, CAS, and the major partners are Institute of Geology and Geophysics (IGG), Institute of Mountain Hazards and Environment (IMHE), Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), and Institute of Geographic Sciences and Natural Resources Research (IGSNRR), CAS.
CAS Strategic Priority Programme (B)