Gao Y.,Nanjing University of Information Science and Technology |
Chen Y.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Zhang L.,China Meteorological Administration Training Center |
Peng T.,Institute of Heavy Rain CMA
Journal of the Meteorological Society of Japan | Year: 2016
From July 1 to 13, 2007, a widespread heavy rainfall event occurred in the Huaihe River Basin (HB) in China, with an average rainfall of nearly 465 mm in the area. The main purpose of this study is to integrate a rainfall estimate by the China New Generation Weather Radar S-band radar (CINRAD-SB) into the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) and analyze the CINRAD-SB rainfall estimation and its impact on the runoff simulation of this type of rare flood event in a region with complex terrain. For the CINRAD-SB rainfall estimation four methods are considered: (1) Z = 300R1.4 (Z: radar reflectivity, R: rainfall intensity); (2) a rainfall estimation error adjustment by using a Kalman Filter (KF); (3) Optimal Interpolation (OI); and (4) the Union method, which is composed of KF and OI. The HEC-HMS is used to investigate the spatial and temporal distribution of the CINRAD-SB rainfall and its impact on the hydrological simulation of the event. Rainfall estimations from the four methods are compared with rain gauge observations. The four methods underestimate the precipitation amounts, while for the Union method the values of the relative bias are closer to zero. The relative bias values of the four methods vary with different rainfall intensity, those of the Union method vary the least among the four methods. This evaluation indicates that runoff simulations based on radar-rainfall could reproduce similar overall patterns to the observed streamflow. The peak discharge contains obvious improvements – for instance, the skill score is 0.6 – in model runs with forcing that is provided by the Union method vs. rain gauge data. These results might guide the improvement of hydrological predictions that are driven by radar rainfall. © 2016, Meteorological Society of Japan.
Yao S.,Nanjing University of Information Science and Technology |
Sun Q.,Nanjing University of Information Science and Technology |
Huang Q.,Nanjing University of Information Science and Technology |
Huang Q.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Chu P.,Jiangsu Sub bureau of East China Regional Air Traffic Management Bureau
Dynamics of Atmospheres and Oceans | Year: 2016
East Asia is known for its monsoon characteristics, but little research has been performed on the intraseasonal time scale of the East Asian winter monsoon (EAWM). In this paper, the extended reanalysis (ERA)-Interim sub-daily data are used to study the surface air temperature intraseasonal oscillation (ISO) of the EAWM. The results show that the air temperature (2-m level) of the EAWM has a dominant period of 10–30 days. Lake Baikal and south China are the centers of the air temperature ISO. An anomalous low frequency (10–30-day filtered) anticyclone corresponds to the intraseasonal cold air. The 10–30-day filtered cold air spreads from Novaya Zemlya to Lake Baikal and even to South China. The ISO of the Arctic Oscillation (AO) index influences the temperature of the EAWM by stimulating Rossby waves in middle latitude, causing meridional circulation, and eventually leads to the temperature ISO of the EAWM. RegCM4 has good performance for the simulation of the air temperature ISO. The simulated results indicate that the plateau is responsible for the southward propagation of the intraseasonal anticyclone. The anticyclone could not reach South China when there was no plateau in western China and its upper reaches. © 2016 The Author(s)
Cao G.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Cao G.,Nanjing University of Information Science and Technology |
He C.,Nanjing University of Information Science and Technology |
Xu W.,Nanjing University of Information Science and Technology
Fluctuation and Noise Letters | Year: 2016
This study investigates the correlation between weather and agricultural futures markets on the basis of detrended cross-correlation analysis (DCCA) cross-correlation coefficients and q-dependent cross-correlation coefficients. In addition, detrended fluctuation analysis (DFA) is used to measure extreme weather and thus analyze further the effect of this condition on agricultural futures markets. Cross-correlation exists between weather and agricultural futures markets on certain time scales. There are some correlations between temperature and soybean return associated with medium amplitudes. Under extreme weather conditions, weather exerts different influences on different agricultural products; for instance, soybean return is greatly influenced by temperature, and weather variables exhibit no effect on corn return. Based on the detrending moving-average cross-correlation analysis (DMCA) coefficient and DFA regression results are similar to that of DCCA coefficient. © 2016 World Scientific Publishing Company.
Zhang W.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Zhang W.,System Dynamics |
Zhang W.,Nanjing University of Information Science and Technology |
Fu B.,University of Hawaii at Manoa |
And 2 more authors.
Weather and Forecasting | Year: 2015
This study investigates the classification of developing and nondeveloping tropical disturbances in the western North Pacific (WNP) through the C4.5 algorithm. A decision tree is built based on this algorithm and can be used as a tool to predict future tropical cyclone (TC) genesis events. The results show that the maximum 800-hPa relative vorticity, SST, precipitation rate, divergence averaged between 1000-and 500-hPa levels, and 300-hPa air temperature anomaly are the five most important variables for separating the developing and nondeveloping tropical disturbances. This algorithm also unravels the thresholds of the five variables (i.e., 4.2 × 10-5 s-1 for maximum 800-hPa relative vorticity, 28.2°C for SST, 0.1 mm h-1 for precipitation rate, -0.7 × 10-6 s-1 for vertically averaged convergence, and 0.5°C for 300-hPa air temperature anomaly). Six rules are derived from the decision tree. The classification accuracy of this decision tree is 81.7% for the 2004-10 cases. The hindcast accuracy for the 2011-13 dataset is 84.6%. © 2015 American Meteorological Society.
Ge F.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Zhi X.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Babar Z.A.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Tang W.,Chongqing Institute of Environmental Science |
Chen P.,Chongqing Meteorological Observatory
Theoretical and Applied Climatology | Year: 2016
The interannual variability of summer monsoon precipitation (1979–2011) over the Indochina Peninsula (ICP) is characterized using the first empirical orthogonal function of 5-month total precipitation (May to September). The leading mode, with a monopole pattern, accounts for 30.6 % of the total variance. Dynamic composites and linear regression analysis indicate that the rainy season precipitation over the ICP is linked to El Niño–Southern Oscillation (ENSO) on interannual scales. The preceding winter [D(−1)JF(0)] negative sea surface temperature (SST) over the Niño-3.4 region is predominantly correlated with the rainy season precipitation over the ICP. Notably, the simultaneous correlation between remote SST anomalies in the Niño-3.4 region and the rainy season precipitation over the ICP is weak. The interannual variation of tropical cyclones modulated by ENSO is a significant contributing factor to the rainy season precipitation over the ICP. However, this relationship is not homogeneous over the ICP if ENSO is considered. Before removing the ENSO signal, enhanced precipitation is present over the northeastern part of the ICP and reduced precipitation appears in the western ICP, especially in coastal areas. In contrast, after removing ENSO, only a minor significant positive precipitation anomaly occurs over the northeastern part of the ICP and the negative anomaly appears particularly in the western and eastern coastal regions. The results obtained through the present study are useful for our understanding of circulation mechanisms and provide information for assessing the ability of regional and global climate models in simulating the climate of Southeast Asia. © 2016 Springer-Verlag Wien
Zhou B.,National Climate Center |
Zhou B.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Wang Z.,National Climate Center
Journal of Geophysical Research Atmospheres | Year: 2015
Using monthly data from the European Centre for Medium-Range Weather Forecasts 40 year Re-Analysis, this study investigated the interannual relationship between the Asian-Pacific Oscillation (APO) and the North Atlantic Oscillation (NAO) for the period of May to August. The NAO is represented by the leading Empirical Orthogonal Function of sea level pressure anomalies over the Atlantic sector. The difference of upper tropospheric eddy air temperature (T′) between Asia and the North Pacific is used to measure the APO. Results clearly show that the APO and the NAO correlated very well on the interannual time scale, with the positive (negative) phase of the APO corresponding to the strong (weak) NAO. Such a relationship is well supported by the atmospheric dynamic process. When the APO is in the positive phase (characterized by the positive T′ anomaly over Asia and the negative T′ anomaly over the North Pacific in the upper troposphere), the upper tropospheric geopotential height increases over Asia and decreases over the North Pacific. Accordingly, anticyclonic circulation and cyclonic circulation anomalies are introduced, respectively, over Asia and south of the North Pacific, and a zonal teleconnection wave train is excited from Asia to the North Atlantic. As a consequence, an anomalous anticyclonic circulation prevails in the low level of the North Atlantic and an anomalous cyclonic circulation appears to its north, which corresponds to the atmospheric pattern of strong NAO. Further study proposes that the quasi-stationary wave pattern emanating from the western North Pacific region may serve as a bridge for this linkage. © 2015. American Geophysical Union. All Rights Reserved.
Babar Z.A.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Zhi X.-F.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Fei G.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters
Arabian Journal of Geosciences | Year: 2015
Response of Indian summer monsoon (ISM) to the historical data of 13 selected models of Coupled Model Intercomparison Project Phase 5 (CMIP5) suite has been investigated by considering the annual precipitation cycle, spatial distribution of rainfall, monsoon index, and domain along with wavelet and empirical orthogonal function (EOF) analysis. The domain of interest focuses on an area between 5°N to 45°N and 45°E to 95°E. NCEP/NCAR reanalysis, Global Precipitation Climatology Project (GPCP) and CMPA dataset are utilized for the period from 1955 to 2004. When compared with the given models, MIROC stands out to be the best suited dataset for monsoon season in Indian subcontinent. An ensemble of all the models has also been considered, and it produces good spatial and temporal distribution maps. However, it is not able to capture the peak values. MIROC has its limitations in capturing average monthly precipitation rate and rainfall distributions when compared to the reference dataset. The representation of Indian summer monsoon rainfall simulation by MIROC suggests it to be considered more consistent for the rainfall simulation projections in this highly complex climate system. This makes it more suitable and reliable for near-term to century rainfall projections in Indian subcontinent. © 2014, Saudi Society for Geosciences.
Zhang L.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Fraedrich K.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Zhu X.,University of Hamburg |
Sielmann F.,University of Hamburg |
Zhi X.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters
Theoretical and Applied Climatology | Year: 2014
The observed winter (DJF) precipitation in Southeast China (1961-2010) is characterized by a monopole pattern of the 3-monthly Standardized Precipitation Index (SPI-3) whose interannual variability is related to the anomalies of East Asian Winter Monsoon (EAWM) systems. Dynamic composites and linear regression analysis indicate that the intensity of EAWM and Siberia High (SH), the position of East Asian Trough (EAT), and El Niño events and sea surface temperature (SST) anomalies over South China Sea (SCS) influence different regions of anomalous Southeast China winter precipitation on interannual scales. The circulation indices (EAWM index, SH index, and EAT index) mainly affect the winter precipitation in the eastern part of Southeast China. El Niño events affect the South China winter precipitation due to the anticyclone anomalies over Philippines. The effect of SCS SST anomalies on the winter precipitation is mainly in the southern part of Yangtze River. Thus, a set of circulation regimes, represented by a handful indices, provide the basis for modeling precipitation anomalies or extremes in future climate projections. © 2014 Springer-Verlag Wien.
Ogwang B.A.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Chen H.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Li X.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
Gao C.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters
Advances in Meteorology | Year: 2014
The influence of topography on east African climate is investigated using the International Centre for Theoretical Physics Regional Climate Model, with focus on October to December season. Results show that the mean rainfall (temperature) significantly reduces (increases) over the region when topography elevation is reduced. Based on the model, when topography over the selected region (KTU) is reduced to 25%, the mean rainfall (temperature) over east Africa is reduced (increased) by about 19% (1.4°C). The maximum rainfall (temperature) reduction (increase) is however observed around the region over which topography is reduced. The reduction in topography elevation resulted in an anomalous moisture divergence at low level and descending motion over the region. KTU topography enhances the surface heat flux over KTU region and tends to enhance convection over both KTU and the east African region. The topography also helps in the generation of the high frequency mesoscale and subsynoptic disturbances over the region. These disturbances produce precipitation over the region and may also enhance precipitation systems over remote areas due to propagation of the disturbances. The magnitude of the zonal wind speed at 850 hpa increases with the decrease in topography elevation. © 2014 Bob Alex Ogwang et al.
Tao W.,CAS Institute of Atmospheric Physics |
Tao W.,Chengdu University of Information Technology |
Huang G.,CAS Institute of Atmospheric Physics |
Huang G.,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters |
And 4 more authors.
International Journal of Climatology | Year: 2015
On the basis of Coupled Model Intercomparison Project phase 5 (CMIP5) models, this study have examined the ability of models to capture the El Niño/Southern Oscillation (ENSO)-Indian Ocean Basin Mode (IOBM) relationship, and investigated the characteristics of interdecadal change of ENSO-IOBM relationship as well as the response of the ENSO-IOBM relationship to the global warming. Among 23 CMIP5 models, the capability of models in representing the IOBM depends largely on the simulation of ENSO. Moreover, half of the models can reproduce the unstable ENSO-IOBM relationship. Considering the simulations of ENSO, ENSO-IOBM relationship and interdecadal change, 6 of 23 CMIP5 models are chosen for further investigation. The interdecadal change of ENSO-IOBM relationship is relative to the three ENSO-related processes. During the high correlation (HC) period, the tropospheric temperature (TT) mechanism, oceanic Rossby waves and antisymmetric wind pattern are strong, prolonging the persistence of IOBM. In comparison, during the low correlation (LC) period, the three processes are weak. The results show that the shallow thermocline in the southwestern Indian Ocean (SWIO), increased interannual variability and prolonged periodicity of ENSO are all responsible for the interdecadal change. Furthermore, the possible changes of ENSO-IOBM relationship in the future are investigated. The ENSO-related tropical Indian Ocean (TIO) warming is strengthened under global warming. Despite the deepened thermocline over SWIO and unchanged ENSO activity, the ENSO-related TIO warming is strengthened by the enhanced TT mechanism, which is caused by the increased saturated specific humidity. The results reveal that there is more downward net heat flux (NHF) over the TIO, which is conducive to the TIO warming, and the latent heat flux (LHF) change makes a great contribution to the NHF change. The weakened upward or strengthened downward LHF is possibly due to the decreased anomalous sea-air temperature difference by strengthened TT mechanism. © 2014 Royal Meteorological Society.