J. Meteor. Res.
  Home    About JMR    Author Guide    Editorial Board    Reviewer List    Subscribe    Volunteers    ACTA
Current Issue  
2018 Vol. 32, No. 5
Published: 2018-10-28

A Review of Climate Change Attribution Studies
Panmao ZHAI, Baiquan ZHOU, Yang CHEN
2018, 32(5): 671-692 [Abstract]( 314 ) HTML PDF (1859 KB)  ( 302 Supplemental Material
Abstract:This paper reviews recent progress in climate change attribution studies. The focus is on the attribution of observed long-term changes in surface temperature, precipitation, circulation, and extremes, as well as that of specific extreme weather and climate events. Based on new methods and better models and observations, the latest studies further verify the conclusions on climate change attribution in the IPCC AR5, and enrich the evidence for anthropogenic influences on weather and climate variables and extremes. The uncertainty of global temperature change attributable to anthropogenic forcings lies in the considerable uncertainty of estimated total radiative forcing due to aerosols, while the uncertainty of precipitation change attribution arises from the limitations of observation and model simulations along with influences from large internal variability. In terms of extreme weather and climate events, it is clear that attribution studies have provided important new insights into the changes in the intensity or frequency of some of these events caused by anthropogenic climate change. The framing of the research question, the methods selected, and the model and statistical methods used all have influences on the results and conclusions drawn in an event attribution study. Overall, attribution studies in China remain inadequate because of limited research focus and the complexity of the monsoon climate in East Asia. Attribution research in China has focused mainly on changes or events related to temperature, such as the attribution of changes in mean and extreme temperature and individual heat wave events. Some progress has also been made regarding the pattern of changes in precipitation and individual extreme rainfall events in China. Nonetheless, gaps remain with respect to the attribution of changes in extreme precipitation, circulation, and drought, as well as to the event attribution such as those related to drought and tropical cyclones. It can be expected that, with the continual development of climate models, ongoing improvements to data, and the introduction of new methods in the future, climate change attribution research will develop accordingly. Additionally, further improvement in climate change attribution will facilitate the development of operational attribution systems for extreme events, as well as attribution studies of climate change impacts.
Sensitivity Study of Anthropogenic Aerosol Indirect Forcing through Cirrus Clouds with CAM5 Using Three Ice Nucleation Parameterizations
Xiangjun SHI, Xiaohong LIU
2018, 32(5): 693-706 [Abstract]( 55 ) HTML PDF (4860 KB)  ( 74 Supplemental Material
Abstract:Quantifying the radiative forcing due to aerosol-cloud interactions especially through cirrus clouds remains challenging because of our limited understanding of aerosol and cloud processes. In this study, we investigate the anthropogenic aerosol indirect forcing (AIF) through cirrus clouds using the Community Atmosphere Model version 5 (CAM5) with a state-of-the-art treatment of ice nucleation. We adopt a new approach to isolate anthropogenic AIF through cirrus clouds in which ice nucleation parameterization is driven by prescribed pre-industrial (PI) and present-day (PD) aerosols, respectively. Sensitivities of anthropogenic ice AIF (i.e., anthropogenic AIF through cirrus clouds) to different ice nucleation parameterizations, homogeneous freezing occurrence, and uncertainties in the cloud microphysics scheme are investigated. Results of sensitivity experiments show that the change (PD minus PI) in global annual mean longwave cloud forcing (i.e., longwave anthropogenic ice AIF) ranges from 0.14 to 0.35 W m-2, the change in global annual mean shortwave cloud forcing (i.e., shortwave anthropogenic ice AIF) from -0.47 to -0.20 W m-2, and the change in net cloud forcing from -0.12 to 0.05 W m-2. Our results suggest that different ice nucleation parameterizations are an important factor for the large uncertainty of anthropogenic ice AIF. Furthermore, improved understanding of the spatial and temporal occurrence characteristics of homogeneous freezing events and the mean states of cirrus cloud properties are also important for constraining anthropogenic ice AIF.
Estimation of the Aerosol Radiative Effect over the Tibetan Plateau Based on the Latest CALIPSO Product
Rui JIA, Yuzhi LIU, Shan HUA, Qingzhe ZHU, Tianbin SHAO
2018, 32(5): 707-722 [Abstract]( 64 ) HTML PDF (8225 KB)  ( 84 Supplemental Material
Abstract:Based on the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) Version 4.10 products released on 8 November 2016, the Level 2 (L2) aerosol product over the Tibetan Plateau (TP) is evaluated and the aerosol radiative effect is also estimated in this study. As there are still some missing aerosol data points in the daytime CALIPSO Version 4.10 L2 product, this study re-calculated the aerosol extinction coefficient to explore the aerosol radiative effect over the TP based on the CALIPSO Level 1 (L1) and CloudSat 2B-CLDCLASS-LIDAR products. The energy budget estimation obtained by using the AODs (aerosol optical depths) from calculated aerosol extinction coefficient as an input to a radiative transfer model shows better agreement with the Earth's Radiant Energy System (CERES) and CloudSat 2B-FLXHR-LIDAR observations than that with the input of AODs from aerosol extinction coefficient from CALIPSO Version 4.10 L2 product. The radiative effect and heating rate of aerosols over the TP are further simulated by using the calculated aerosol extinction coefficient. The dust aerosols may heat the atmosphere by retaining the energy in the layer. The instantaneous heating rate can be as high as 5.5 K day-1 depending on the density of the dust layers. Overall, the dust aerosols significantly affect the radiative energy budget and thermodynamic structure of the air over the TP, mainly by altering the shortwave radiation budget. The significant influence of dust aerosols over the TP on the radiation budget may have important implications for investigating the atmospheric circulation and future regional and global climate.
Influences of the Internal Mixing of Anthropogenic Aerosols on Global Aridity Change
Hua ZHANG, Chen ZHOU, Shuyun ZHAO
2018, 32(5): 723-733 [Abstract]( 53 ) HTML PDF (5472 KB)  ( 68 Supplemental Material
Abstract:Influences of the mixing treatments of anthropogenic aerosols on their effective radiative forcing (ERF) and global aridity are evaluated by using the BCC_AGCM2.0_CUACE/Aero, an aerosol-climate online coupled model. Simulations show that the negative ERF due to external mixing (EM, a scheme in which all aerosol particles are treated as independent spheres formed by single substance) aerosols is largely reduced by the partial internal mixing (PIM, a scheme in which some of the aerosol particles are formed by one absorptive and one scattering substance) method. Compared to EM, PIM aerosols have much stronger absorptive ability and generally weaker hygroscopicity, which would lead to changes in radiative forcing, hence to climate. For the global mean values, the ERFs due to anthropogenic aerosols since the pre-industrial are -1.02 and -1.68 W m-2 for PIM and EM schemes, respectively. The variables related to aridity such as global mean temperature, net radiation flux at the surface, and the potential evaporation capacity are all decreased by 2.18/1.61 K, 5.06/3.90 W m-2, and 0.21/0.14 mm day-1 since 1850 for EM and PIM schemes, respectively. According to the changes in aridity index, the anthropogenic aerosols have caused general humidification over central Asia, South America, Africa, and Australia, but great aridification over eastern China and the Tibetan Plateau since the pre-industrial in both mixing schemes. However, the aridification is considerably alleviated in China, but intensified in the Arabian Peninsula and East Africa in the PIM scheme.
The Observation of Ice-Nucleating Particles Active at Temperatures above -15℃ and Its Implication on Ice Formation in Clouds
Kai BI, Xincheng MA, Yunbo CHEN, Shizuo FU, Huiwen XUE
2018, 32(5): 734-743 [Abstract]( 120 ) HTML PDF (3157 KB)  ( 1521 Supplemental Material
Abstract:A series of measurements of ice-nucleating particles (INPs) were performed at two sites in Beijing. At the Beijing Meteorological Service (BMS) site, which was an urban site, no INPs were found to be active above -15℃. However, at the Yanjiaping (YJP) site, which was a rural site, the concentration of INPs active at temperatures above -15℃ was found to be as high as 1.73 g-1. Two parameterizations were constructed by respectively fitting the data obtained at BMS site and YJP site. The two parameterizations, as well as another parameterization from the literature, were implemented into a parcel model to investigate the effect of INPs active above -15℃ on phase partitioning in mixed-phase clouds. At a vertical velocity of 0.01 m s-1, which is typical for stratiform clouds associated with frontal systems, the INPs active above -15℃ nucleate ice crystals at low levels. The growth of these ice crystals remarkably reduces both the maximum liquid water mixing ratio and the altitude where the maximum liquid water mixing ratio is reached. When the vertical velocity of the parcel is increased to 0.1 m s-1 or an even higher value, the evolution of liquid water mixing ratio is not controlled by the INPs active above -15℃ but those active below -15℃.
Analysis of Paths and Sources of Moisture for the South China Rainfall during the Presummer Rainy Season of 1979-2014
Yangruixue CHEN, Yali LUO
2018, 32(5): 744-757 [Abstract]( 81 ) HTML PDF (6879 KB)  ( 90
Abstract:The paths and sources of moisture supplied to South China during two periods of the presummer rainy season (April-June) of 1979-2014, i.e., before and after the onset of the summer monsoon over the South China Sea (SCS), are investigated by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. During the premonsoon-onset period, the moisture transport trajectories are clustered into 6 groups, with four ocean-originating paths providing 83.9% and two continent-originating paths (originating over Lake Baikal and the Persian Gulf) contributing the remaining 16.1% of the total moisture. The two Pacific-originating paths, from the western Pacific Ocean and the East China Sea, combined account for about 46%, the SCS-originating path contributes about 24.3%, while the Bay of Bengal-originating path accounts for 13.6% of the total moisture over South China. The trajectories during the postmonsoon-onset period are clustered into 4 groups, with three southwesterly paths (from the Arabian Sea, the central Indian Ocean, and the western Indian Ocean, respectively) accounting for more than 76% and the sole Pacific-originating path accounting for 23.8% of the total moisture. The formation of the moisture transport trajectories is substantially affected by the topography, especially the Tibetan Plateau and the Indian and Indo-China Peninsulas. The SCS region contributes the most moisture during both periods (35.3% and 31.1%). The Pacific Ocean is ranked second during the former period (about 21.0%) but its contribution is reduced to 5.0% during the latter period, while the contribution from the Bay of Bengal and the Indian Ocean combined increases from 17.1% to 43.2%.
Effects of Updated RegCM4 Land Use Data on Near-Surface Temperature Simulation in China
Yulong REN, Yaohui LI, Zhaoxia PU, Tiejun ZHANG, Haixia DUAN, Wei WANG
2018, 32(5): 758-767 [Abstract]( 43 ) HTML PDF (3060 KB)  ( 77 Supplemental Material
Abstract:Biogeophysical effects of land use and land cover (LULC) changes play a significant role in modulating climate on various spatial scales. In this study, a set of recent LULC products with a spatial resolution of 500 m was developed in China for update in RegCM4 (regional climate model version 4). Two sets of comparative numerical experiments were conducted to study the effects of LULC changes on near-surface temperature simulation. The results show that after LULC changes, areas of crops and mixed woodlands as well as urban areas increase over entire China, accompanied with greatly expanded mixed farming and forests/field mosaics in southern China, and reduced areas of 1) irrigated crops and short grasses in northern China and the Tibetan Plateau, and 2) semi-desert and desert in northwestern China. Improvements in the LULC data clearly result in more accurate simulations of the near-surface temperature. Specifically, increasing latent heat and longwave albedo due to enhanced LULC in certain areas lead to reduction in land surface temperature (LST), while changes in shortwave albedo and sensible heat also exert a great influence on the LST. Overall, these parameter adjustments reduce the biases in near-surface temperature simulation.
Subseasonal Zonal Oscillation of the Western Pacific Subtropical High during Early Summer
Weina GUAN, Xuejuan REN, Wei SHANG, Haibo HU
2018, 32(5): 768-780 [Abstract]( 95 ) HTML PDF (8689 KB)  ( 79 Supplemental Material
Abstract:This study examines the features and dynamical processes of subseasonal zonal oscillation of the western Pacific subtropical high (WPSH) during early summer, by performing a multivariate empirical orthogonal function (MV-EOF) analysis on daily winds and a diagnosis on potential vorticity (PV) at 500 hPa for the period 1979-2016. The first MV-EOF mode is characterized by an anticyclonic anomaly occupying southeastern China to subtropical western North Pacific regions. It has a period of 10-25 days and represents zonal shift of the WPSH. When the WPSH stretches more westward, the South Asian high (SAH) extends more eastward. Above-normal precipitation is observed over the Yangtze-Huaihe River (YHR) basin. Suppressed convection with anomalous descending motion is located over the subtropical western North Pacific. The relative zonal movement of the SAH and the WPSH helps to establish an anomalous local vertical circulation of ascending motion with upper-level divergence over the YHR basin and descending motion with upper-level convergence over the subtropical western Pacific. The above local vertical circulation provides a dynamic condition for persistent rainfall over the YHR basin. An enhanced southwest flow over the WPSH's western edge transports more moisture to eastern China, providing a necessary water vapor condition for the persistent rainfall over the YHR basin. A potential vorticity diagnosis reveals that anomalous diaba-tic heating is a main source for PV generation. The anomalous cooling over the subtropical western Pacific produces a local negative PV center at 500 hPa. The anomalous heating over the YHR basin generates a local positive PV center. The above south-north dipolar structure of PV anomaly along with the climatological southerly flow leads to northward advection of negative PV. These two processes are conducive to the WPSH's westward extension. The vertical advection process is unfavorable to the westward extension but contributes to the eastward retreat of the WPSH.
Water Vapor Transport Related to the Interdecadal Shift of Summer Precipitation over Northern East Asia in the Late 1990s
Po HU, Minghao WANG, Liu YANG, Xiaojuan WANG, Guolin FENG
2018, 32(5): 781-793 [Abstract]( 63 ) HTML PDF (6051 KB)  ( 89 Supplemental Material
Abstract:In this study, an interdecadal shift of summer precipitation over northern East Asia (NEA) was identified, demonstrating that summer precipitation decreased abruptly after 1998/99. The synchronous shift in summer moisture budget and water vapor transport over NEA was further investigated by using the NCEP/NCAR reanalysis data. The results indicate that water vapor transported northward into NEA from three low-latitude paths was limited because most water vapor was transported eastward. Water vapor transported from the westerly path in mid-high (WMH) latitudes exhibited significant correlations with summer precipitation in NEA and experienced a significant adjustment in the late 1990s. Regarding the spatial distributions of water vapor transport, less input was found through the western boundary while more output occurred through the eastern boundary of NEA, and zonal water vapor transport fluxes mainly concentrated at the low to middle levels, which led to the summer precipitation shift in NEA around the late 1990s. Furthermore, it is also confirmed that the wind anomalies (rather than the moisture disturbance) as the dominant internal dynamic factor and Pacific Decadal Oscillation/Atlantic Multidecadal Oscillation (PDO/AMO) as possible external force played important roles in influencing the water vapor transport and causing the summer precipitation shift over NEA in the late 1990s.
Improving Multi-Model Ensemble Forecasts of Tropical Cyclone Intensity Using Bayesian Model Averaging
Xiaojiang SONG, Yuejian ZHU, Jiayi PENG, Hong GUAN
2018, 32(5): 794-803 [Abstract]( 51 ) HTML PDF (2807 KB)  ( 51 Supplemental Material
Abstract:This paper proposes a method for multi-model ensemble forecasting based on Bayesian model averaging (BMA), aiming to improve the accuracy of tropical cyclone (TC) intensity forecasts, especially forecasts of minimum surface pressure at the cyclone center (Pmin). The multi-model ensemble comprises three operational forecast models:the Global Forecast System (GFS) of NCEP, the Hurricane Weather Research and Forecasting (HWRF) models of NCEP, and the Integrated Forecasting System (IFS) of ECMWF. The mean of a predictive distribution is taken as the BMA forecast. In this investigation, bias correction of the minimum surface pressure was applied at each forecast lead time, and the distribution (or probability density function, PDF) of Pmin was used and transformed. Based on summer season forecasts for three years, we found that the intensity errors in TC forecast from the three models varied significantly. The HWRF had a much smaller intensity error for short lead-time forecasts. To demonstrate the proposed methodology, cross validation was implemented to ensure more efficient use of the sample data and more reliable testing. Comparative analysis shows that BMA for this three-model ensemble, after bias correction and distribution transformation, provided more accurate forecasts than did the best of the ensemble members (HWRF), with a 5%-7% decrease in root-mean-square error on average. BMA also outperformed the multi-model ensemble, and it produced "predictive variance" that represented the forecast uncertainty of the member models. In a word, the BMA method used in the multi-model ensemble forecasting was successful in TC intensity forecasts, and it has the potential to be applied to routine operational forecasting.
Remote Sensing of Tropical Cyclone Thermal Structure from Satellite Microwave Sounding Instruments: Impacts of Optimal Channel Selection on Retrievals
Yang HAN, Fuzhong WENG
2018, 32(5): 804-818 [Abstract]( 23 ) HTML PDF (8323 KB)  ( 21 Supplemental Material
Abstract:Accurate information on atmospheric temperature of tropical cyclones (TCs) is important for monitoring and prediction of their developments and evolution. For hurricanes, temperature anomaly in the upper troposphere can be derived from Advanced Microwave Sounding Unit (AMSU) and Advanced Technology Microwave Sounder (ATMS) through either regression-based or variational retrieval algorithms. This study investigates the dependency of TC warm core structure on emission and scattering processes in the forward operator used for radiance computations in temperature retrievals. In particular, the precipitation scattering at ATMS high-frequency channels can significantly change the retrieval outcomes. The simulation results in this study reveal that the brightness temperatures at 183 GHz could be depressed by 30-50 K under cloud ice water path of 1.5 mm, and thus, the temperature structure in hurricane atmosphere could be distorted if the ice cloud scattering was inaccurately characterized in the retrieval system. It is found that for Hurricanes Irma, Maria, and Harvey that occurred in 2017, their warm core anomalies retrieved from ATMS temperature sounding channels 4-15 were more reasonable and realistic, compared with the retrievals from all other channel combinations and earlier hurricane simulation results.
Possible Impact of Spatial and Temporal Non-Uniformity in Land Surface Temperature Data on Trend Estimation
Zhiyu LI, Wenjun ZHANG, Haiming XU
2018, 32(5): 819-828 [Abstract]( 60 ) HTML PDF (4345 KB)  ( 43 Supplemental Material
Abstract:The present work investigates possible impact of the non-uniformity in observed land surface temperature on trend estimation, based on Climatic Research Unit (CRU) Temperature Version 4 (CRUTEM4) monthly temperature datasets from 1900 to 2012. The CRU land temperature data exhibit remarkable non-uniformity in spatial and temporal features. The data are characterized by an uneven spatial distribution of missing records and station density, and display a significant increase of available sites around 1950. Considering the impact of missing data, the trends seem to be more stable and reliable when estimated based on data with < 40% missing percent, compared to the data with above 40% missing percent. Mean absolute error (MAE) between data with < 40% missing percent and global data is only 0.011℃ (0.014℃) for 1900-50 (1951-2012). The associated trend estimated by reliable data is 0.087℃ decade-1 (0.186℃ decade-1) for 1900-50 (1951-2012), almost the same as the trend of the global data. However, due to non-uniform spatial distribution of missing data, the global signal seems mainly coming from the regions with good data coverage, especially for the period 1900-50. This is also confirmed by an extreme test conducted with the records in the United States and Africa. In addition, the influences of spatial and temporal non-uniform features in observation data on trend estimation are significant for the areas with poor data coverage, such as Africa, while insignificant for the countries with good data coverage, such as the United States.
Asymmetric Ridge-Furrow and Film Cover Improves Plant Morphological Traits and Light Utilization in Rain-Fed Maize
Wanlin DONG, Hang YU, Lizhen ZHANG, Ruonan WANG, Qi WANG, Qingwu XUE, Zhihua PAN, Zhigang SUN, Xuebiao PAN
2018, 32(5): 829-838 [Abstract]( 61 ) HTML PDF (2422 KB)  ( 97 Supplemental Material
Abstract:Light is one of the most important natural resources for plant growth. Light interception (LI) and use efficiency (LUE) are often affected by the structure of canopy caused by growing pattern and agronomy managements. Agronomy practices, such as the ridge-furrow system and plastic film cover, might affect the leaf morphology and then light transmission within the canopy, thus change light extinction coefficient (k), and LI and LUE. The objective of this study is to quantify LI and LUE in rain-fed maize (Zea Mays L.), a major cropping system in Northeast China, under different combinations of ridge-furrow and film covering ratios. The tested ridge-furrow system (DRF:"double ridges and furrows") was asymmetric and alternated with wide ridge (0.70 m in width and 0.15 m in height), narrow furrow (0.10 m), narrow ridge (0.40 m in width and 0.20 m in height), and narrow furrow (0.10 m). Field experiments were conducted in 2013 and 2014 in Jilin Province, Northeast China. Four treatments were tested:no ridges and plastic film cover (control, NRF), ridges without film cover (DRF0), ridges with 58% film cover (DRF58), and ridges with 100% film cover (DRF100). DRF0 significantly increased LI by 9% compared with NRF, while film cover showed a marginal improvement. Specific leaf area in DRF experiments with film cover was significantly lower than in NRF, and leaf angle was 16% higher than in NRF, resulting in a 4% reduction in k. LUE of maize was not increased by DRF0, but was significantly enhanced by covering film in other DRF experiments, especially by 22% in DRF100. The increase of LUE by film cover was due to a greater biomass production and a lower assimilation portioning to vegetative organs, which caused a higher harvest index. The results could help farmers to optimize maize managements, especially in the region with decreased solar radiation under climate change.
  Paper Search
Search DOI Adv Search
  Featured Collections
  Conference Links
  Journal Links
Copyright © Journal of Meteorological Research
Tel:86-10-68407634, 86-10-58993104    Zip/Postal Code: 100081    E-mail: cmsams@cms1924.org
Supported by: Beijing Magtech