This study investigated the simulations of three months of seasonal tropical cyclone （TC） activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment （CTL）, the TC freq...This study investigated the simulations of three months of seasonal tropical cyclone （TC） activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment （CTL）, the TC frequency was considerably overestimated. Additionally, the tracks of some TCs tended to have larger radii of curvature and were shifted eastward. The large-scale environments of westerly monsoon flows and subtropical Pacific highs were unreasonably simulated. The overestimated frequency of TC formation was attributed to a strengthened westerly wind field in the southern quadrants of the TC center. In comparison with the experiment with the spectral nudging method, the strengthened wind speed was mainly modulated by large-scale flow that was greater than approximately 1000 km in the model domain. The spurious formation and undesirable tracks of TCs in the CTL were considerably improved by reproducing realistic large-scale atmospheric monsoon circulation with substantial adjustment between large-scale flow in the model domain and large-scale boundary forcing modified by the spectral nudging method. The realistic monsoon circulation took a vital role in simulating realistic TCs. It revealed that, in the downscaling from large-scale fields for regional climate simulations, scale interaction between model-generated regional features and forced large-scale fields should be considered, and spectral nudging is a desirable method in the downscaling method.展开更多
An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-...An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year(1960–2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the qualitycontrolled subsurface ocean temperature objective analyses(EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square(RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m(OHT100 m)is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT100 m convergent to one value after several times iteration,indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model.展开更多
基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方...基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方案以及松弛系数进行了数值试验研究。一系列试验结果表明,不论采用显式还是隐式Nudging松弛方案,模式结果的偏差会随着松弛系数的增加先减小后增大,松弛系数最优值为1×10^(-5);当松弛系数太大时,会造成模式的溢出。Nudging松弛项采用隐式差分方案可以显著提高松弛系数的阈值;松弛系数在适当的取值范围内时,加入Nudging松弛项的数值试验描述的潮汐特征要明显优于未加Nudging松弛项的数值试验描述的潮汐特征;在最优Nudging松弛方案下,Nudging松弛方法对全日分潮的振幅模拟准确度可提高50%,对半日分潮的振幅模拟准确度可提高56%。试验结果也表明了Nudging方法作为一种简单的同化方法的可行性和有效性。展开更多
A set of major disruptive political,socio-economic,technological,and ecological trends presents serious issues for tourism policy makers,regulators,and operators alike.In this turbulent context,how best to attempt to ...A set of major disruptive political,socio-economic,technological,and ecological trends presents serious issues for tourism policy makers,regulators,and operators alike.In this turbulent context,how best to attempt to predict tourist behaviours?In tourism research the dominant rationalistic approach to decision-making does provide some useful insights across tourism choice.However,it seems increasingly less suited to the often relatively unplanned,hedonic,opportunistic,and impulsive decision-making that often characterises tourists’behaviours on-site within a destination,and more generally to the behaviours of Generation Y and Generation Z.More generally,it is arguable that rational models of motivation and decision-making systematically underestimate the importance of affective processes in tourists’behaviours.In this paper,we explore the implications of employing a much more naturalistic approach to decision-making at both the policy level and at the frontline of tourism operations.展开更多
In this study, an approach combining dynamical initialization and large-scale spectral nudging is proposed to achieve improved numerical simulations of tropical cyclones （TCs）, including track, structure, intensity,...In this study, an approach combining dynamical initialization and large-scale spectral nudging is proposed to achieve improved numerical simulations of tropical cyclones （TCs）, including track, structure, intensity, and their changes, based on the Advanced Weather Research and Forecasting （ARW-WRF） model. The effectiveness of the approach has been demonstrated with a case study of Typhoon Megi （2010）. The ARW-WRF model with the proposed approach realistically reproduced many aspects of Typhoon Megi in a 7-day-long simulation. In particular, the model simulated quite well not only the storm track and intensity changes but also the structure changes before, during, and after its landfall over the Luzon Island in the northern Philippines, as well as after it reentered the ocean over the South China Sea （SCS）. The results from several sensitivity experiments demonstrate that the proposed approach is quite effective and ideal for achieving realistic simulations of real TCs, and thus is useful for understanding the TC inner-core dynamics, and structure and intensity changes.展开更多
The sensitivity of a regional climate model （RCM） to cumulus parameterization （CUPA） schemes in modeling summer precipitation over East Asia has been investigated by using the fifth-generation Pennsylvania State U...The sensitivity of a regional climate model （RCM） to cumulus parameterization （CUPA） schemes in modeling summer precipitation over East Asia has been investigated by using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model （PSU-NCAR MM5）. The feasibility of physical ensemble and the effect of interior （spectral） nudging are also assessed. The RCM simulations are evaluated against the NCEP/NCAR reanalysis data and NCEP/CPC precipitation data for three summers （JJA） in 1991, 1998, and 2003. The results show that the RCM is highly sensitive to CUPA schemes. Different CUPA schemes cause distinctive characteristics in the modeling of JJA precipitation and the intraseasonal （daily） variability of regional precipitation. The sensitivity of the RCM simulations to the CUPA schemes is reduced by adopting the spectral nudging technique, which enables the RCM to reproduce more realistic large-scale circulations at the upper levels of the atmosphere as well as near the surface, and better precipitation simulation in the selected experiments. The ensemble simulations using different CUPA schemes show higher skills than individual members for both control runs and spectral nudging runs. The physical ensemble adopting the spectral nudging technique shows the highest downscaling skill in capturing the general circulation patterns for all experiments and improved temporal distributions of precipitation in some regions.展开更多
The Nutri-Score is a 5-color front-of-pack nutrition label designed to provide consumers with an easily understandable guideline to the healthiness of food products.The impact that the Nutri-Score may have on consumer...The Nutri-Score is a 5-color front-of-pack nutrition label designed to provide consumers with an easily understandable guideline to the healthiness of food products.The impact that the Nutri-Score may have on consumers'choices is unclear since different experimental paradigms have found vastly different effect sizes.In the present study,we have investigated how student participants change a hypothetical personal 1-daydietary plan after a learning phase during which they learn about the Nutri-Scores of the available food items.Participants were instructed to compose a healthy diet plan in order that the question of whether the NutriScore would improve their ability to compose a healthy dietary plan could be investigated,independent of the question of whether they would apply this knowledge in their ordinary lives.We found a substantial(Cohen's d=0.86)positive impact on nutritional quality(as measured by the Nutrient Profiling System score of the Food Standards Agency)and a medium-sized(Cohen's d=0.43)reduction of energy content.Energy content reduction was larger for participants who had initially composed plans with higher energy content.The results suggest that the Nutri-Score has the potential to guide consumers to healthier food choices.It remains unclear,however,whether this potential will be reflected in real-life dietary choices.展开更多
From 21 to 22 July 2012, Beijing and its surrounding areas suffered from an extreme precipitation event that was unprecedented relative to the past 61 years, and the event caused 79 deaths and reported direct economic...From 21 to 22 July 2012, Beijing and its surrounding areas suffered from an extreme precipitation event that was unprecedented relative to the past 61 years, and the event caused 79 deaths and reported direct economic losses of11.64 billion Yuan. However, current models have difficulty to simulate the spatial and temporal distribution characteristics of such events. Therefore, improved simulations of these extreme precipitation processes are needed. In this study, nudging methods, including grid nudging(GN) and spectral nudging(SN), and more accurate surface type data retrieved from remote sensing were used in the Weather Research and Forecasting(WRF) model to simulate this extreme precipitation case. When the default city underlay surface of the WRF model was replaced by a more accurate urban surface(NU), the precipitation intensity could be better simulated, but the peak moment of precipitation seriously lagged. Although the peak precipitation intensity simulated by the GN experiment was weak, the simulated precipitation time was basically consistent with the observations. Using GN in only the outside domain could better simulate precipitation peaks, while using GN in both the inside and outside domains could better simulate the spatial distribution characteristics of precipitation. Additionally, the precipitation from GN could be better simulated than that from SN. Overall, the two nudging methods could contribute to better simulations of this case because the nudging methods could improve the simulations of 500-hPa geopotential height, 850-hPa water vapor transport, and low-level weather systems, which are the key factors in adjusting the spatial and temporal distributions of precipitation. This study is the basis for the investigation of the mechanism and attribution of extreme precipitation processes,and the results are of great significance for promoting understanding of and mitigating disasters caused by extreme precipitation.展开更多
基金funded by the Korea Meteorological Administration Research and Development Program under grant KMIPA 2015–2083
文摘This study investigated the simulations of three months of seasonal tropical cyclone （TC） activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment （CTL）, the TC frequency was considerably overestimated. Additionally, the tracks of some TCs tended to have larger radii of curvature and were shifted eastward. The large-scale environments of westerly monsoon flows and subtropical Pacific highs were unreasonably simulated. The overestimated frequency of TC formation was attributed to a strengthened westerly wind field in the southern quadrants of the TC center. In comparison with the experiment with the spectral nudging method, the strengthened wind speed was mainly modulated by large-scale flow that was greater than approximately 1000 km in the model domain. The spurious formation and undesirable tracks of TCs in the CTL were considerably improved by reproducing realistic large-scale atmospheric monsoon circulation with substantial adjustment between large-scale flow in the model domain and large-scale boundary forcing modified by the spectral nudging method. The realistic monsoon circulation took a vital role in simulating realistic TCs. It revealed that, in the downscaling from large-scale fields for regional climate simulations, scale interaction between model-generated regional features and forced large-scale fields should be considered, and spectral nudging is a desirable method in the downscaling method.
基金The National Key R&D Program of China under contract No. 2017YFA0604201the National Natural Science Foundation of China under contract Nos 41876012 and 41861144015.
文摘An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year(1960–2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the qualitycontrolled subsurface ocean temperature objective analyses(EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square(RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m(OHT100 m)is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT100 m convergent to one value after several times iteration,indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model.
文摘基于全球海洋模式OGCTM(Ocean General Circulation and Tide Model),利用19年(1992—2011年)的卫星高度计资料调和分析得到全球分潮调和常数回报逐时正压潮水位;采用Nudging(牛顿松弛逼近)方法进行潮汐同化,针对Nudging松弛项的差分方案以及松弛系数进行了数值试验研究。一系列试验结果表明,不论采用显式还是隐式Nudging松弛方案,模式结果的偏差会随着松弛系数的增加先减小后增大,松弛系数最优值为1×10^(-5);当松弛系数太大时,会造成模式的溢出。Nudging松弛项采用隐式差分方案可以显著提高松弛系数的阈值;松弛系数在适当的取值范围内时,加入Nudging松弛项的数值试验描述的潮汐特征要明显优于未加Nudging松弛项的数值试验描述的潮汐特征;在最优Nudging松弛方案下,Nudging松弛方法对全日分潮的振幅模拟准确度可提高50%,对半日分潮的振幅模拟准确度可提高56%。试验结果也表明了Nudging方法作为一种简单的同化方法的可行性和有效性。
文摘A set of major disruptive political,socio-economic,technological,and ecological trends presents serious issues for tourism policy makers,regulators,and operators alike.In this turbulent context,how best to attempt to predict tourist behaviours?In tourism research the dominant rationalistic approach to decision-making does provide some useful insights across tourism choice.However,it seems increasingly less suited to the often relatively unplanned,hedonic,opportunistic,and impulsive decision-making that often characterises tourists’behaviours on-site within a destination,and more generally to the behaviours of Generation Y and Generation Z.More generally,it is arguable that rational models of motivation and decision-making systematically underestimate the importance of affective processes in tourists’behaviours.In this paper,we explore the implications of employing a much more naturalistic approach to decision-making at both the policy level and at the frontline of tourism operations.
基金Supported by the National Basic Research and Development (973) Program of China (2009CB421505)National Natural Science Foundation of China (41130964)+1 种基金the United States NOAA/JHT grant (NA09OAR4310081)support has been provided by the JAMSTEC, NASA, and NOAA through their sponsorships of the International Pacific Research Center (IPRC) in the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii at Manoa
文摘In this study, an approach combining dynamical initialization and large-scale spectral nudging is proposed to achieve improved numerical simulations of tropical cyclones （TCs）, including track, structure, intensity, and their changes, based on the Advanced Weather Research and Forecasting （ARW-WRF） model. The effectiveness of the approach has been demonstrated with a case study of Typhoon Megi （2010）. The ARW-WRF model with the proposed approach realistically reproduced many aspects of Typhoon Megi in a 7-day-long simulation. In particular, the model simulated quite well not only the storm track and intensity changes but also the structure changes before, during, and after its landfall over the Luzon Island in the northern Philippines, as well as after it reentered the ocean over the South China Sea （SCS）. The results from several sensitivity experiments demonstrate that the proposed approach is quite effective and ideal for achieving realistic simulations of real TCs, and thus is useful for understanding the TC inner-core dynamics, and structure and intensity changes.
基金Supported by the "973" National Basic Research Program of China under Grant Nos. 2011CB952004 and 2006CB400500the National Natural Science Foundation of China under Grant Nos. 40705029 and 40830639
文摘The sensitivity of a regional climate model （RCM） to cumulus parameterization （CUPA） schemes in modeling summer precipitation over East Asia has been investigated by using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model （PSU-NCAR MM5）. The feasibility of physical ensemble and the effect of interior （spectral） nudging are also assessed. The RCM simulations are evaluated against the NCEP/NCAR reanalysis data and NCEP/CPC precipitation data for three summers （JJA） in 1991, 1998, and 2003. The results show that the RCM is highly sensitive to CUPA schemes. Different CUPA schemes cause distinctive characteristics in the modeling of JJA precipitation and the intraseasonal （daily） variability of regional precipitation. The sensitivity of the RCM simulations to the CUPA schemes is reduced by adopting the spectral nudging technique, which enables the RCM to reproduce more realistic large-scale circulations at the upper levels of the atmosphere as well as near the surface, and better precipitation simulation in the selected experiments. The ensemble simulations using different CUPA schemes show higher skills than individual members for both control runs and spectral nudging runs. The physical ensemble adopting the spectral nudging technique shows the highest downscaling skill in capturing the general circulation patterns for all experiments and improved temporal distributions of precipitation in some regions.
文摘The Nutri-Score is a 5-color front-of-pack nutrition label designed to provide consumers with an easily understandable guideline to the healthiness of food products.The impact that the Nutri-Score may have on consumers'choices is unclear since different experimental paradigms have found vastly different effect sizes.In the present study,we have investigated how student participants change a hypothetical personal 1-daydietary plan after a learning phase during which they learn about the Nutri-Scores of the available food items.Participants were instructed to compose a healthy diet plan in order that the question of whether the NutriScore would improve their ability to compose a healthy dietary plan could be investigated,independent of the question of whether they would apply this knowledge in their ordinary lives.We found a substantial(Cohen's d=0.86)positive impact on nutritional quality(as measured by the Nutrient Profiling System score of the Food Standards Agency)and a medium-sized(Cohen's d=0.43)reduction of energy content.Energy content reduction was larger for participants who had initially composed plans with higher energy content.The results suggest that the Nutri-Score has the potential to guide consumers to healthier food choices.It remains unclear,however,whether this potential will be reflected in real-life dietary choices.
基金the National Natural Science Foundation of China (41521004, 41905013, and 41975088)Strategic Priority Research Program of Chinese Academy of Sciences (XDA2006010301)China University Research Talents Recruitment Program [111Project (B13045)]。
文摘From 21 to 22 July 2012, Beijing and its surrounding areas suffered from an extreme precipitation event that was unprecedented relative to the past 61 years, and the event caused 79 deaths and reported direct economic losses of11.64 billion Yuan. However, current models have difficulty to simulate the spatial and temporal distribution characteristics of such events. Therefore, improved simulations of these extreme precipitation processes are needed. In this study, nudging methods, including grid nudging(GN) and spectral nudging(SN), and more accurate surface type data retrieved from remote sensing were used in the Weather Research and Forecasting(WRF) model to simulate this extreme precipitation case. When the default city underlay surface of the WRF model was replaced by a more accurate urban surface(NU), the precipitation intensity could be better simulated, but the peak moment of precipitation seriously lagged. Although the peak precipitation intensity simulated by the GN experiment was weak, the simulated precipitation time was basically consistent with the observations. Using GN in only the outside domain could better simulate precipitation peaks, while using GN in both the inside and outside domains could better simulate the spatial distribution characteristics of precipitation. Additionally, the precipitation from GN could be better simulated than that from SN. Overall, the two nudging methods could contribute to better simulations of this case because the nudging methods could improve the simulations of 500-hPa geopotential height, 850-hPa water vapor transport, and low-level weather systems, which are the key factors in adjusting the spatial and temporal distributions of precipitation. This study is the basis for the investigation of the mechanism and attribution of extreme precipitation processes,and the results are of great significance for promoting understanding of and mitigating disasters caused by extreme precipitation.
