Chen Z.,Wuhan Institute of Heavy Rain |
Chen Z.,Wuhan Region Climate Center
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2010
Using the yearly series of maximum 10 min averaged wind velocity observed by Yuyang weather stations from 1952 to 2000, the gale characteristics of Yuyang weather stations was analyzed. The reference wind velocity and design wind velocity were calculated by adopting the function of Extreme I and referencing the observed wind datum along Yangtze River nearby bridge location. Several conclusions are listed as following: (1) the bridge location takes EN wind as dominant wind direction and extreme value of maximum 10 min wind velocity is 24.7 m/s. (2) The annually averaged maximum 10 min wind velocity of the 10 meter high for different return periods(100, 50, 30, 10 year) are respectively 27.6 m/s, 25.4 m/s, 23.8 m/s and 20.2 m/s. (3) the averaged maximum 10 min wind velocity of the 10 meter high of bridge location for different return periods(100, 50, 30, 10 year) are respectively 29.0 m/s, 26.7 m/s, 25.0 m/s and 21.2 m/s. Finally, the design reference wind speed of every 10 m layer within 300 m high is extrapolated by using the index change of wind velocity in the surface layer changed by the height, which can be referred for design and construction of the bridge.
Shi P.,Chinese Academy of Fishery Sciences |
Chen Z.,Wuhan Institute of Heavy Rain |
Yang Q.,Jiangxi Agricultural University |
Harris M.K.,Texas A&M University |
Xiao M.,Wuhan University
Ecology and Evolution | Year: 2014
Climate change is expected to have a significant effect on the first flowering date (FFD) in plants flowering in early spring. Prunus yedoensis Matsum is a good model plant for analyzing this effect. In this study, we used a degree day model to analyze the effect of air temperatures on the FFDs of P. yedoensis at Wuhan University from a long-time series from 1951 to 2012. First, the starting date (=7 February) is determined according to the lowest correlation coefficient between the FFD and the daily average accumulated degree days (ADD). Second, the base temperature (=-1.2°C) is determined according to the lowest root mean square error (RMSE) between the observed and predicted FFDs based on the mean of 62-year ADDs. Finally, based on this combination of starting date and base temperature, the daily average ADD of every year was calculated. Performing a linear fit of the daily average ADD to year, we find that there is an increasing trend that indicates climate warming from a biological climatic indicator. In addition, we find that the minimum annual temperature also has a significant effect on the FFD of P. yedoensis using the generalized additive model. This study provides a method for analyzing the climate change on the FFD in plants' flowering in early spring. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Liu Z.-X.,Macheng Meteorological Bureau |
Zhu H.-L.,Macheng Meteorological Bureau |
Chen Z.-H.,Wuhan Institute of Heavy Rain
Yantu Lixue/Rock and Soil Mechanics | Year: 2010
Beijing-Kowloon Railway is a new main artery linking Beijing with Kowloon of Hongkong that has been finished and opened to traffic in June 1996. The Jianghuai Section is an interval of 306.1 km from the Huaihe River to the Yangtze River or from Huaibin railway station of Henan Province to Qichun railway station of Hubei Province. Because of complicated topography and heavy raining, collapsed disasters of the roadbeds have become the main damages. According to the statistics, 455 sites of collapsed disasters with 53 000 m of road damages are recorded from 1997 to 2007 along the Jianghuai Section. Basing on the geological background, all cases of collapsed disasters of the roadbeds and meteorological data of 10 meteorological stations from 1997 to 2007 along the Jianghuai Section of Beijing-Kowloon Railway, the rock situations are classified; the occurrence frequency and intensity of collapsed disasters of the roadbeds are graded; and the rainfall in 24-72 h preceding every case are analyzed in detail. Then the conditions of geological backgrounds and precipitation conditions in favor of the happening of collapsed disasters of the roadbeds are obtained and graded; the requirement for the conditions of precipitation especially heavy rain under different geological conditions are commented on; a map with the grades of the happening of collapsed disasters of the roadbeds around the Jianghuai Section of Beijing-Kowloon Railway are drawn out; and some countermeasure methods and a routing map of how to prevent and control collapsed disasters are given. It is clear that the combined action of the weak geological conditions with strong rainfall is the root causes of collapsed disasters of the some roadbeds.
PubMed | Chinese Academy of Fishery Sciences, Wuhan University, Jiangxi Agricultural University, Wuhan Institute of Heavy Rain and Texas A&M University
Type: Journal Article | Journal: Ecology and evolution | Year: 2014
Climate change is expected to have a significant effect on the first flowering date (FFD) in plants flowering in early spring. Prunus yedoensis Matsum is a good model plant for analyzing this effect. In this study, we used a degree day model to analyze the effect of air temperatures on the FFDs of P.yedoensis at Wuhan University from a long-time series from 1951 to 2012. First, the starting date (=7 February) is determined according to the lowest correlation coefficient between the FFD and the daily average accumulated degree days (ADD). Second, the base temperature (=-1.2C) is determined according to the lowest root mean square error (RMSE) between the observed and predicted FFDs based on the mean of 62-year ADDs. Finally, based on this combination of starting date and base temperature, the daily average ADD of every year was calculated. Performing a linear fit of the daily average ADD to year, we find that there is an increasing trend that indicates climate warming from a biological climatic indicator. In addition, we find that the minimum annual temperature also has a significant effect on the FFD of P.yedoensis using the generalized additive model. This study provides a method for analyzing the climate change on the FFD in plants flowering in early spring.
Xu W.,National Meteorological Information Center |
Ni Y.,Chinese Academy of Meteorological Sciences |
Wang X.,Wuhan Institute of Heavy Rain |
Qiu X.,Anhui Meteorological Observatory
Acta Meteorologica Sinica | Year: 2012
The evolution of a mesoscale convective system (MCS) that caused strong precipitation in the northern area of Dabie Mountain during 21-22 June 2008 is analyzed, along with the evolution of the associated meso-β-scale convective vortex (MCV). The mesoscale reanalysis data generated by the Local Analysis and Prediction System (LAPS) at a 3-km horizontal resolution and a 1-h time resolution during the South China Heavy Rainfall Experiment (SCHeREX) were utilized. The results show that two processes played key roles in the enhancement of convective instability. First, the mesoscale low-level jet strengthened and shifted eastward, leading to the convergence of warm-wet airflow and increasing convective instability at middle and low levels. Second, the warm-wet airflow interacted with the cold airflow from the north, causing increased vertical vorticity in the vicinity of steeply sloping moist isentropic surfaces. The combined action of these two processes caused the MCS to shift progressively eastward. Condensation associated with the MCS released latent heat and formed a layer of large diabatic heating in the middle troposphere, increasing the potential vorticity below this layer. This increase in potential vorticity created favorable conditions for the development of a low-level vortex circulation. The vertical motion associated with this low-level vortex further promoted the development of convection, creating a positive feedback between the deep convection and the low-level vortex circulation. This feedback mechanism not only promoted the maturation of the MCS, but also played the primary role in the evolution of the MCV. The MCV formed and developed due to the enhancement of the positive feedback that accompanied the coming together of the center of the vortex and the center of the convection. The positive feedback peaked and the MCV matured when these two centers converged. The positive feedback weakened and the MCV began to decay as the two centers separated and diverged. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2012.
Zhi X.,Nanjing University of Information Science and Technology |
Qi H.,Nanjing University of Information Science and Technology |
Bai Y.,Nanjing University of Information Science and Technology |
Lin C.,Wuhan Institute of Heavy Rain
Acta Meteorologica Sinica | Year: 2012
Based on the ensemble mean outputs of the ensemble forecasts from the ECMWF (European Centre for Medium-Range Weather Forecasts), JMA (Japan Meteorological Agency), NCEP (National Centers for Environmental Prediction), and UKMO (United Kingdom Met Office) in THORPEX (The Observing System Research and Predictability Experiment) Interactive Grand Global Ensemble (TIGGE) datasets, for the Northern Hemisphere (10°-87.5°N, 0°-360°) from 1 June 2007 to 31 August 2007, this study carried out multimodel ensemble forecasts of surface temperature and 500-hPa geopotential height, temperature and winds up to 168 h by using the bias-removed ensemble mean (BREM), the multiple linear regression based superensemble (LRSUP), and the neural network based superensemble (NNSUP) techniques for the forecast period from 8 to 31 August 2007. The forecast skills are verified by using the root-mean-square errors (RMSEs). Comparative analysis of forecast results by using the BREM, LRSUP, and NNSUP shows that the multimodel ensemble forecasts have higher skills than the best single model for the forecast lead time of 24-168 h. A roughly 16% improvement in RMSE of the 500-hPa geopotential height is possible for the superensemble techniques (LRSUP and NNSUP) over the best single model for the 24-120-h forecasts, while it is only 8% for BREM. The NNSUP is more skillful than the LRSUP and BREM for the 24-120-h forecasts. But for 144-168-h forecasts, BREM, LRSUP, and NNSUP forecast errors are approximately equal. In addition, it appears that the BREM forecasting without the UKMO model is more skillful than that including the UKMO model, while the LRSUP forecasting in both cases performs approximately the same. A running training period is used for BREM and LRSUP ensemble forecast techniques. It is found that BREM and LRSUP, at each grid point, have different optimal lengths of the training period. In general, the optimal training period for BREM is less than 30 days in most areas, while for LRSUP it is about 45 days. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2012.
Zhang L.-P.,Wuhan University |
Zhang L.-P.,Wuhan Institute of Heavy Rain |
Qin L.-L.,Wuhan University |
Hu Z.-F.,Beijing Water Utilities Bureau of Haidian District |
Zeng S.-D.,Wuhan University
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2010
The change of surface water resources in the water source area of the Middle Route of South-to-North Water Diversion Project in the future will directly affect the reliability of the whole project. It is an important basis for trans-valley water resources deployment and management. Based on the digital elevation model, land used information and soil type data in the water source area of the Project, the applicability of the SWAT model in this basin is investigated by using the observation data obtained from 1980 to 1987 to calibrate the parameters of the model. According to the Fourth Assessment Report of multi-mode climate model results for the Intergovernmental Panel on Climate Change, the responsed precipitation, air temperature, runoff and evaporation under different Special Report on Emissions Scenarios in the 21st Century is analyzed. Compared with the baseline period, The analysis results show that the temperature and the annual precipitation will continue to increase, but the runoff in the catchment will be reduced at first and then increased, the runoff will begin to increase in the forties of the 21st Century. The result indicates that the water resources will reduce in the early 21st Century and will increase in the mid-late. The future climate change will have a little influence on the runoff of the water source area, and thus will generally be favorable to the South-to-North Water Transfer Project.
Du J.,National Oceanic and Atmospheric Administration |
Yu R.,Chinese Meteorological Administration CMA |
Cui C.,Wuhan Institute of Heavy Rain |
Li J.,Wuhan Institute of Heavy Rain
Acta Oceanologica Sinica | Year: 2014
Using NCEP short range ensemble forecast (SREF) system, demonstrated two fundamental on-going evolutions in numericalweather prediction (NWP) are through ensemblemethodology. One evolution is the shift from traditional single-value deterministic forecast to flow-dependent (not statistical) probabilistic forecast to address forecast uncertainty. Another is from a one-way observation-prediction systemshifting to an interactive two-way observation-prediction system to increase predictability of a weather system. In the first part, how ensemble spread from NCEP SREF predicting ensemble-mean forecast error was evaluated over a period of about a month. The result shows that the current capability of predicting forecast error by the 21-member NCEP SREF has reached to a similar or even higher level than that of current state-of-the-art NWP models in predicting precipitation, e.g., the spatial correlation between ensemble spread and absolute forecast error has reached 0.5 or higher at 87 h (3.5 d) lead time on average for some meteorological variables. This demonstrates that the current operational ensemble system has already had preliminary capability of predicting the forecast errorwith usable skill, which is a remarkable achievement as of today. Given the good spread-skill relation, the probability derived from the ensemble was also statistically reliable, which is the most important feature a useful probabilistic forecast should have. The second part of this research tested an ensemble-based interactive targeting (E-BIT) method. Unlike other mathematically-calculated objective approaches, thismethod is subjective or human interactive based on information from an ensemble of forecasts. A numerical simulation study was performed to eight real atmospheric cases with a 10-member, bred vector-based mesoscale ensemble using the NCEP regional spectralmodel (RSM, a sub-component of NCEP SREF) to prove the concept of this E-BITmethod. Themethod seems to workmost effective for basic atmospheric state variables, moderately effective for convective instabilities and least effective for precipitations. Precipitation is a complex result of many factors and, therefore, a more challenging field to be improved by targeted observation. © The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2014.
Sun L.,Institute of Meteorological science of Jilin Province |
Sun L.,Wuhan Institute of Heavy Rain |
Sun L.,Latitude |
Shen B.,Institute of Meteorological science of Jilin Province |
And 3 more authors.
Advances in Atmospheric Sciences | Year: 2010
The characteristics of moisture transport and budget of widespread heavy rain and local heavy rain events in Northeast China are studied using the NCEP-NCAR reanalysis 6-hourly and daily data and daily precipitation data of 200 stations in Northeast China from 1961-2005. The results demonstrate that during periods with widespread heavy rain in Northeast China, the Asian monsoon is very active and the monsoonal northward moisture transport is strengthened significantly. The widespread heavy rainfall obtains enhanced water vapor supply from large regions where the water vapor mainly originates from the Asian monsoon areas, which include the East Asian subtropical monsoon area, the South China Sea, and the southeast and southwest tropical monsoon regions. There are several branches of monsoonal moisture current converging on East China and its coastal areas, where they are strengthened and then continue northward into Northeast China. Thus, the enhanced northward monsoonal moisture transport is the key to the widespread heavy rain in Northeast China. In contrast, local heavy rainfall in Northeast China derives water vapor from limited areas, transported by the westerlies. Local evaporation also plays an important role in the water vapor supply and local recycling process of moisture. In short, the widespread heavy rains of Northeast China are mainly caused by water vapor advection brought by the Asian monsoon, whereas local heavy rainfall is mainly caused by the convergence of the westerly wind field. © 2010 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.
Xu J.,Wuhan Institute of Heavy Rain |
Zhang B.,Wuhan Institute of Heavy Rain |
Wang M.,Wuhan Institute of Heavy Rain |
Wang H.,Weather Modification Office of Hubei Province
Annales Geophysicae | Year: 2012
In this study, the Weather Research and Forecasting model was used to simulate the diurnal variation in summer precipitation over the Tibetan Plateau (TP) at a cloudresolving scale. Compared with the TRMM, precipitation data shows that the model can well simulate the diurnal rainfall cycle with an overall late-afternoon maximum precipitation in the central TP and a nighttime maximum in the southern edge. The simulated diurnal variations in regional circulation and thermodynamics are in good correspondence with the precipitation diurnal cycles in the central and southern edge of TP, respectively. A possible mechanism responsible for the nocturnal precipitation maximum in the southern edge has been proposed, indicating the importance of the TP in regulating the regional circulation and precipitation. © Author(s) 2012.