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Lei Wang
,
Tandong Yao
,
Chenhao Chai
,
Lan Cuo
,
Fengge Su
,
Fan Zhang
,
Zhijun Yao
,
Yinsheng Zhang
,
Xiuping Li
,
Jia Qi
,
Zhidan Hu
,
Jingshi Liu
, and
Yuanwei Wang

Abstract

Monitoring changes in river runoff at the Third Pole (TP) is important because rivers in this region support millions of inhabitants in Asia and are very sensitive to climate change. Under the influence of climate change and intensified cryospheric melt, river runoff has changed markedly at the TP, with significant effects on the spatial and temporal water resource distribution that threaten water supply and food security for people living downstream. Despite some in situ observations and discharge estimates from state-of-the-art remote sensing technology, the total river runoff (TRR) for the TP has never been reliably quantified, and its response to climate change remains unclear. As part of the Chinese Academy of Sciences’ “Pan-Third Pole Environment Study for a Green Silk Road,” the TP-River project aims to construct a comprehensive runoff observation network at mountain outlets (where rivers leave the mountains and enter the plains) for 13 major rivers in the TP region, thereby enabling TRR to be accurately quantified. The project also integrates discharge estimates from remote sensing and cryosphere–hydrology modeling to investigate long-term changes in TRR and the relationship between the TRR variations and westerly/monsoon. Based on recent efforts, the project provides the first estimate (656 ± 23 billion m3) of annual TRR for the 13 TP rivers in 2018. The annual river runoff at the mountain outlets varies widely between the different TP rivers, ranging from 2 to 176 billion m3, with higher values mainly corresponding to rivers in the Indian monsoon domain, rather than in the westerly domain.

Open access
Lanqiang Bai
,
Zhiyong Meng
,
Ling Huang
,
Lijun Yan
,
Zhaohui Li
,
Xuehu Mai
,
Yipeng Huang
,
Dan Yao
, and
Xi Wang

Abstract

This work presents an integrated damage, visual, and radar analysis of a tropical cyclone (TC) tornado that has not been documented as detailed as midlatitude tornadoes. On 4 October 2015, an enhanced Fujita 3 (EF3) tornado spawned into Typhoon Mujigae and hit Foshan, Guangdong Province, China. This tornado was generated in a minisupercell ∼350 km northeast of the TC center and lasted about 32 minutes, leaving a southeast-to-northwest damage swath 30.85 km long and 20–570 m wide. Near-surface wind patterns and the size of the tornado, juxtaposition of the condensation funnel with the damage swath and radar signatures, and consistency between near-surface wind speed estimated from visual observations and that estimated using EF scale were revealed based on ground and aerial surveys, radar and surface observations, photographs, and tornado videos. Tornado videos showed two occurrences of vertical subvortices followed by the formation of a horizontal vortex. Some features of the tornado, the parent supercell and mesocyclone, and the convective environment were compared to their U.S. counterparts. This work provides a case review of a tornado with the most comprehensive information ever in China. Damage indicators used to estimate the tornado intensity in this Chinese case were compared with those in the United States, demonstrating the potential applicability of the EF scale in tornado damage surveys outside the United States.

Open access
Lei Wang
,
Lan Cuo
,
Dongliang Luo
,
Fengge Su
,
Qinghua Ye
,
Tandong Yao
,
Jing Zhou
,
Xiuping Li
,
Ning Li
,
He Sun
,
Lei Liu
,
Yuanwei Wang
,
Tian Zeng
,
Zhidan Hu
,
Ruishun Liu
,
Chenhao Chai
,
Guangpeng Wang
,
Xiaoyang Zhong
,
Xiaoyu Guo
,
Haoqiang Zhao
,
Huabiao Zhao
, and
Wei Yang

Abstract

Upper Brahmaputra (UB) is the largest (∼240,000 km2) river basin of the Tibetan Plateau, where hydrological processes are highly sensitive to climate change. However, constrained by difficult access and sparse in situ observations, the variations in precipitation, glaciers, frozen ground, and vegetation across the UB basin remain largely unknown, and consequently the impacts of climate change on streamflow cannot be accurately assessed. To fill this gap, this project aims to establish a basinwide, large-scale observational network (that includes hydrometeorology, glacier, frozen ground, and vegetation observations), which helps quantify the UB runoff processes under climate–cryosphere–vegetation changes. At present, a multisphere observational network has been established throughout the catchment: 1) 12 stations with custom-built weighing automatic rain/snow meters and temperature probes to obtain elevation-dependent gradients; 2) 9 stations with soil moisture/temperature observations at four layers (10, 40, 80, 120 cm) covering Alpine meadow, grasslands, shrub, and forest to measure vegetation (biomass and vegetation types) and soil (physical properties) simultaneously; 3) 34 sets of probes to monitor frozen ground temperatures from 4,500 to 5,200 m elevation (100-m intervals), and two observation systems to monitor water and heat transfer processes in frozen ground at Xuegela (5,278 m) and Mayoumula (5,256 m) Mountains, for improved mapping of permafrost and active layer characteristics; 4) 5 sets of altimetry discharge observations along ungauged cross sections to supplement existing operational gauges; 5) high-precision glacier boundary and ice-surface elevation observations at Namunani Mountain with differential GPS, to supplement existing glacier observations for validating satellite imagery. This network provides an excellent opportunity to monitor UB catchment processes in great detail.

Full access
Dan Fu
,
Justin Small
,
Jaison Kurian
,
Yun Liu
,
Brian Kauffman
,
Abishek Gopal
,
Sanjiv Ramachandran
,
Zhi Shang
,
Ping Chang
,
Gokhan Danabasoglu
,
Katherine Thayer-Calder
,
Mariana Vertenstein
,
Xiaohui Ma
,
Hengkai Yao
,
Mingkui Li
,
Zhao Xu
,
Xiaopei Lin
,
Shaoqing Zhang
, and
Lixin Wu

Abstract

The development of high-resolution, fully coupled, regional Earth system model systems is important for improving our understanding of climate variability, future projections, and extreme events at regional scales. Here we introduce and present an overview of the newly developed Regional Community Earth System Model (R-CESM). Different from other existing regional climate models, R-CESM is based on the Community Earth System Model version 2 (CESM2) framework. We have incorporated the Weather Research and Forecasting (WRF) Model and Regional Ocean Modeling System (ROMS) into CESM2 as additional components. As such, R-CESM can be conveniently used as a regional dynamical downscaling tool for the global CESM solutions or/and as a standalone high-resolution regional coupled model. The user interface of R-CESM follows that of CESM, making it readily accessible to the broader community. Among countless potential applications of R-CESM, we showcase here a few preliminary studies that illustrate its novel aspects and value. These include 1) assessing the skill of R-CESM in a multiyear, high-resolution, regional coupled simulation of the Gulf of Mexico; 2) examining the impact of WRF and CESM ocean–atmosphere coupling physics on tropical cyclone simulations; and 3) a convection-permitting simulation of submesoscale ocean–atmosphere interactions. We also discuss capabilities under development such as (i) regional refinement using a high-resolution ROMS nested within global CESM and (ii) “online” coupled data assimilation. Our open-source framework (publicly available at https://github.com/ihesp/rcesm1) can be easily adapted to a broad range of applications that are of interest to the users of CESM, WRF, and ROMS.

Full access
Yaohui Li
,
Xing Yuan
,
Hongsheng Zhang
,
Runyuan Wang
,
Chenghai Wang
,
Xianhong Meng
,
Zhiqiang Zhang
,
Shanshan Wang
,
Yang Yang
,
Bo Han
,
Kai Zhang
,
Xiaoping Wang
,
Hong Zhao
,
Guangsheng Zhou
,
Qiang Zhang
,
Qing He
,
Ni Guo
,
Wei Hou
,
Cunjie Zhang
,
Guoju Xiao
,
Xuying Sun
,
Ping Yue
,
Sha Sha
,
Heling Wang
,
Tiejun Zhang
,
Jinsong Wang
, and
Yubi Yao

Abstract

A major experimental drought research project entitled “Mechanisms and Early Warning of Drought Disasters over Northern China” (DroughtEX_China) was launched by the Ministry of Science and Technology of China in 2015. The objective of DroughtEX_China is to investigate drought disaster mechanisms and provide early-warning information via multisource observations and multiscale modeling. Since the implementation of DroughtEX_China, a comprehensive V-shape in situ observation network has been established to integrate different observational experiment systems for different landscapes, including crops in northern China. In this article, we introduce the experimental area, observational network configuration, ground- and air-based observing/testing facilities, implementation scheme, and data management procedures and sharing policy. The preliminary observational and numerical experimental results show that the following are important processes for understanding and modeling drought disasters over arid and semiarid regions: 1) the soil water vapor–heat interactions that affect surface soil moisture variability, 2) the effect of intermittent turbulence on boundary layer energy exchange, 3) the drought–albedo feedback, and 4) the transition from stomatal to nonstomatal control of plant photosynthesis with increasing drought severity. A prototype of a drought monitoring and forecasting system developed from coupled hydroclimate prediction models and an integrated multisource drought information platform is also briefly introduced. DroughtEX_China lasted for four years (i.e., 2015–18) and its implementation now provides regional drought monitoring and forecasting, risk assessment information, and a multisource data-sharing platform for drought adaptation over northern China, contributing to the global drought information system (GDIS).

Full access
Fan Yang
,
Qing He
,
Jianping Huang
,
Ali Mamtimin
,
Xinghua Yang
,
Wen Huo
,
Chenglong Zhou
,
Xinchun Liu
,
Wenshou Wei
,
Caixia Cui
,
Minzhong Wang
,
Hongjun Li
,
Lianmei Yang
,
Hongsheng Zhang
,
Yuzhi Liu
,
Xinqian Zheng
,
Honglin Pan
,
Lili Jin
,
Han Zou
,
Libo Zhou
,
Yongqiang Liu
,
Jiantao Zhang
,
Lu Meng
,
Yu Wang
,
Xiaolin Qin
,
Yongjun Yao
,
Houyong Liu
,
Fumin Xue
, and
Wei Zheng

Abstract

As the second-largest shifting sand desert worldwide, the Taklimakan Desert (TD) represents the typical aeolian landforms in arid regions as an important source of global dust aerosols. It directly affects the ecological environment and human health across East Asia. Thus, establishing a comprehensive environment and climate observation network for field research in the TD region is essential to improve our understanding of the desert meteorology and environment, assess its impact, mitigate potential environmental issues, and promote sustainable development. With a nearly 20-yr effort under the extremely harsh conditions of the TD, the Desert Environment and Climate Observation Network (DECON) has been established completely covering the TD region. The core of DECON is the Tazhong station in the hinterland of the TD. Moreover, the network also includes 4 satellite stations located along the edge of the TD for synergistic observations, and 18 automatic weather stations interspersed between them. Thus, DECON marks a new chapter of environmental and meteorological observation capabilities over the TD, including dust storms, dust emission and transport mechanisms, desert land–atmosphere interactions, desert boundary layer structure, ground calibration for remote sensing monitoring, and desert carbon sinks. In addition, DECON promotes cooperation and communication within the research community in the field of desert environments and climate, which promotes a better understanding of the status and role of desert ecosystems. Finally, DECON is expected to provide the basic support necessary for coordinated environmental and meteorological monitoring and mitigation, joint construction of ecologically friendly communities, and sustainable development of central Asia.

Full access
Tandong Yao
,
Yongkang Xue
,
Deliang Chen
,
Fahu Chen
,
Lonnie Thompson
,
Peng Cui
,
Toshio Koike
,
William K.-M. Lau
,
Dennis Lettenmaier
,
Volker Mosbrugger
,
Renhe Zhang
,
Baiqing Xu
,
Jeff Dozier
,
Thomas Gillespie
,
Yu Gu
,
Shichang Kang
,
Shilong Piao
,
Shiori Sugimoto
,
Kenichi Ueno
,
Lei Wang
,
Weicai Wang
,
Fan Zhang
,
Yongwei Sheng
,
Weidong Guo
,
Ailikun
,
Xiaoxin Yang
,
Yaoming Ma
,
Samuel S. P. Shen
,
Zhongbo Su
,
Fei Chen
,
Shunlin Liang
,
Yimin Liu
,
Vijay P. Singh
,
Kun Yang
,
Daqing Yang
,
Xinquan Zhao
,
Yun Qian
,
Yu Zhang
, and
Qian Li

Abstract

The Third Pole (TP) is experiencing rapid warming and is currently in its warmest period in the past 2,000 years. This paper reviews the latest development in multidisciplinary TP research associated with this warming. The rapid warming facilitates intense and broad glacier melt over most of the TP, although some glaciers in the northwest are advancing. By heating the atmosphere and reducing snow/ice albedo, aerosols also contribute to the glaciers melting. Glacier melt is accompanied by lake expansion and intensification of the water cycle over the TP. Precipitation has increased over the eastern and northwestern TP. Meanwhile, the TP is greening and most regions are experiencing advancing phenological trends, although over the southwest there is a spring phenological delay mainly in response to the recent decline in spring precipitation. Atmospheric and terrestrial thermal and dynamical processes over the TP affect the Asian monsoon at different scales. Recent evidence indicates substantial roles that mesoscale convective systems play in the TP’s precipitation as well as an association between soil moisture anomalies in the TP and the Indian monsoon. Moreover, an increase in geohazard events has been associated with recent environmental changes, some of which have had catastrophic consequences caused by glacial lake outbursts and landslides. Active debris flows are growing in both frequency of occurrences and spatial scale. Meanwhile, new types of disasters, such as the twin ice avalanches in Ali in 2016, are now appearing in the region. Adaptation and mitigation measures should be taken to help societies’ preparation for future environmental challenges. Some key issues for future TP studies are also discussed.

Full access
Yongkang Xue
,
Ismaila Diallo
,
Aaron A. Boone
,
Tandong Yao
,
Yang Zhang
,
Xubin Zeng
,
J. David Neelin
,
William K. M. Lau
,
Yan Pan
,
Ye Liu
,
Xiaoduo Pan
,
Qi Tang
,
Peter J. van Oevelen
,
Tomonori Sato
,
Myung-Seo Koo
,
Stefano Materia
,
Chunxiang Shi
,
Jing Yang
,
Constantin Ardilouze
,
Zhaohui Lin
,
Xin Qi
,
Tetsu Nakamura
,
Subodh K. Saha
,
Retish Senan
,
Yuhei Takaya
,
Hailan Wang
,
Hongliang Zhang
,
Mei Zhao
,
Hara Prasad Nayak
,
Qiuyu Chen
,
Jinming Feng
,
Michael A. Brunke
,
Tianyi Fan
,
Songyou Hong
,
Paulo Nobre
,
Daniele Peano
,
Yi Qin
,
Frederic Vitart
,
Shaocheng Xie
,
Yanling Zhan
,
Daniel Klocke
,
Ruby Leung
,
Xin Li
,
Michael Ek
,
Weidong Guo
,
Gianpaolo Balsamo
,
Qing Bao
,
Sin Chan Chou
,
Patricia de Rosnay
,
Yanluan Lin
,
Yuejian Zhu
,
Yun Qian
,
Ping Zhao
,
Jianping Tang
,
Xin-Zhong Liang
,
Jinkyu Hong
,
Duoying Ji
,
Zhenming Ji
,
Yuan Qiu
,
Shiori Sugimoto
,
Weicai Wang
,
Kun Yang
, and
Miao Yu

Abstract

Subseasonal-to-seasonal (S2S) precipitation prediction in boreal spring and summer months, which contains a significant number of high-signal events, is scientifically challenging and prediction skill has remained poor for years. Tibetan Plateau (TP) spring observed surface ­temperatures show a lag correlation with summer precipitation in several remote regions, but current global land–atmosphere coupled models are unable to represent this behavior due to significant errors in producing observed TP surface temperatures. To address these issues, the Global Energy and Water Exchanges (GEWEX) program launched the “Impact of Initialized Land Temperature and Snowpack on Subseasonal-to-Seasonal Prediction” (LS4P) initiative as a community effort to test the impact of land temperature in high-mountain regions on S2S prediction by climate models: more than 40 institutions worldwide are participating in this project. After using an innovative new land state initialization approach based on observed surface 2-m temperature over the TP in the LS4P experiment, results from a multimodel ensemble provide evidence for a causal relationship in the observed association between the Plateau spring land temperature and summer precipitation over several regions across the world through teleconnections. The influence is underscored by an out-of-phase oscillation between the TP and Rocky Mountain surface temperatures. This study reveals for the first time that high-mountain land temperature could be a substantial source of S2S precipitation predictability, and its effect is probably as large as ocean surface temperature over global “hotspot” regions identified here; the ensemble means in some “hotspots” produce more than 40% of the observed anomalies. This LS4P approach should stimulate more follow-on explorations.

Free access