Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on th...Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.展开更多
By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boun...By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boundary layer height determined by using a bulk Richardson(Ri)number approach,was studied in this paper.It was found that the boundary layer heights in both summer and winter months showed diurnal changes and the daily cycle was deeper in summer,which agreed well with the previous studies;the monthly averaged height was 103–1112 m and 89–450 m in summer and winter,respectively;the morning rise began at 0700 LT/1000 LT in summer/winter and the evening transition occurred at 1900 LT in both seasons;the maximum height occurred in the afternoon for most cases,except some peaks found in the winter night;the surface temperature and relative humidity dominated the variations of summer height,while the diurnal variation shown in January 2007 might have some connections with the dynamical processes in the lower troposphere,besides the surface effects.展开更多
A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the meso...A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However, the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front, and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently, the heavy rainfall forecast was improved.展开更多
The quality of ensemble forecasting is seriously affected by sample quality.In this study,the distributions of ensemble members based on the observed track and intensity of tropical cyclones(TCs)were optimized and the...The quality of ensemble forecasting is seriously affected by sample quality.In this study,the distributions of ensemble members based on the observed track and intensity of tropical cyclones(TCs)were optimized and their influence on the simulation results was analyzed.Simulated and observed tracks and intensities of TCs were compared and these two indicators were combined and weighted to score the sample.Samples with higher scores were retained and samples with lower scores were eliminated to improve the overall quality of the ensemble forecast.For each sample,the track score and intensity score were added as the final score of the sample with weight proportions of 10 to 0,9 to 1,8 to 2,7 to 3,6 to 4,5 to 5.These were named as“tr”,“91”,“82”,“73”,“64”,and“55”,respectively.The WRF model was used to simulate five tropical cyclones in the northwestern Pacific to test the ability of this scheme to improve the forecast track and intensity of these cyclones.The results show that the sample optimization effectively reduced the track and intensity error,“55”usually had better performance on the short-term intensity prediction,and“tr”had better performance in short-term track prediction.From the overall performance of the track and intensity simulation,“91”was the best and most stable among all sample optimization schemes.These results may provide some guidance for optimizing operational ensemble forecasting of TCs.展开更多
We apply our sky map reconstruction method for transit type interferometers to the Tianlai cylin- der array. The method is based on spherical harmonic decomposition, and can be applied to a cylindrical array as well a...We apply our sky map reconstruction method for transit type interferometers to the Tianlai cylin- der array. The method is based on spherical harmonic decomposition, and can be applied to a cylindrical array as well as dish arrays and we can compute the instrument response, synthesized beam, transfer func- tion and noise power spectrum. We consider cylinder arrays with feed spacing larger than half a wavelength and, as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome using arrays with a different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configura- tions.展开更多
The shadow and observation intensity of a black hole surrounded by a thin spherical accretion in the Randall–Sundrum brane world model are investigated.The bulk metric depends on the tidal charge parameter,q,and defo...The shadow and observation intensity of a black hole surrounded by a thin spherical accretion in the Randall–Sundrum brane world model are investigated.The bulk metric depends on the tidal charge parameter,q,and deformation parameter,C.It reduces to the metric that possesses similar form with the Reissner–Nordström metric if C=0.It is shown that the radius of the photon sphere of this black hole depends only on the tidal charge parameter.The radius of the photon sphere decreases with higher q.The observation intensity is mainly influenced by the tidal charge parameter,q,and the deformation parameter,C,is of secondary importance.In the optical observation,the black holes appear brighter with higher q or lower C.展开更多
We investigated the shadows and optical appearances of a new type of regular black holes(BHs)with a Minkowski core under various spherical accretion scenarios.These BHs are constructed by modifying the Newtonian poten...We investigated the shadows and optical appearances of a new type of regular black holes(BHs)with a Minkowski core under various spherical accretion scenarios.These BHs are constructed by modifying the Newtonian potential based on the minimum observable length in the Generalized Uncertainty Principle(GUP).They correspond one-to-one with traditional regular BHs featuring a de-Sitter(dS)core(such as Bardeen/Hayward BHs),characterized by a quantum gravity effect parameter(α_(0))and spacetime deformation factor(n).We found that the characteristic parameters give rise to some novel observable features.For these new BHs,both the shadow and photon sphere radii decrease with the increase in α_(0),while the observed specific intensity increases.Conversely,as n increases,the shadow and photon sphere radii increase,while the observed specific intensity decreases.Under different spherical accretion scenarios,the shadows and photon sphere radii remain identical;however,the observed specific intensity is greater under static spherical accretion than under infalling spherical accretion.Additionally,we found that these regular BHs with different cores exhibit variations in shadows and optical appearances,particularly under static spherical accretion.Compared with Bardeen BH,the new BHs exhibit a lower observed specific intensity,a dimmer photon ring,and smaller shadow and photon sphere radii.Larger values of α_(0) lead to more significant differences,and a similar trend was also observed when comparing with Hayward BH.Under infalling spherical accretion,the regular BHs with different cores exhibit only slight differences in observed specific intensity,which become more evident when α_(0) is relatively large.This suggests that the unique spacetime features of these regular BHs with different cores can be distinguished through astronomical observation.展开更多
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/333/46。
文摘Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2012CB825605)the National Natural Science Foundation of China(Grant No.41304125)ZHANG YeHui acknowledges support from the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘By using the eight-times-daily sampling data from an intensive radiosonde observation campaign at Yichang(111°18′E,30°42′N),China in August 2006 and January 2007,the diurnal variation of the planetary boundary layer height determined by using a bulk Richardson(Ri)number approach,was studied in this paper.It was found that the boundary layer heights in both summer and winter months showed diurnal changes and the daily cycle was deeper in summer,which agreed well with the previous studies;the monthly averaged height was 103–1112 m and 89–450 m in summer and winter,respectively;the morning rise began at 0700 LT/1000 LT in summer/winter and the evening transition occurred at 1900 LT in both seasons;the maximum height occurred in the afternoon for most cases,except some peaks found in the winter night;the surface temperature and relative humidity dominated the variations of summer height,while the diurnal variation shown in January 2007 might have some connections with the dynamical processes in the lower troposphere,besides the surface effects.
文摘A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However, the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front, and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently, the heavy rainfall forecast was improved.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFC1507602,2017YFC1501603)the National Natural Science Foundation of China(Grant No.41975136)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2019A1515011118)Sci-entific research project of Shanghai Science and Technology Com-mission(19dz1200101).
文摘The quality of ensemble forecasting is seriously affected by sample quality.In this study,the distributions of ensemble members based on the observed track and intensity of tropical cyclones(TCs)were optimized and their influence on the simulation results was analyzed.Simulated and observed tracks and intensities of TCs were compared and these two indicators were combined and weighted to score the sample.Samples with higher scores were retained and samples with lower scores were eliminated to improve the overall quality of the ensemble forecast.For each sample,the track score and intensity score were added as the final score of the sample with weight proportions of 10 to 0,9 to 1,8 to 2,7 to 3,6 to 4,5 to 5.These were named as“tr”,“91”,“82”,“73”,“64”,and“55”,respectively.The WRF model was used to simulate five tropical cyclones in the northwestern Pacific to test the ability of this scheme to improve the forecast track and intensity of these cyclones.The results show that the sample optimization effectively reduced the track and intensity error,“55”usually had better performance on the short-term intensity prediction,and“tr”had better performance in short-term track prediction.From the overall performance of the track and intensity simulation,“91”was the best and most stable among all sample optimization schemes.These results may provide some guidance for optimizing operational ensemble forecasting of TCs.
基金supported by the MOST 863 program(Grant 2012AA121701)the CAS Repair and Procurement grant+4 种基金supported by PNCG,Observatoire de Paris,Irfu/CEA and LAL/CNRSsupported by the China Scholarship Councilsupported by the CAS Strategic Priority Research Program(XDB09020301)the National Natural Science Foundation of China(NSFC,Grant 11373030)supported by the NSFC(Grant 11473044)
文摘We apply our sky map reconstruction method for transit type interferometers to the Tianlai cylin- der array. The method is based on spherical harmonic decomposition, and can be applied to a cylindrical array as well as dish arrays and we can compute the instrument response, synthesized beam, transfer func- tion and noise power spectrum. We consider cylinder arrays with feed spacing larger than half a wavelength and, as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome using arrays with a different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configura- tions.
基金Supported by the National Natural Science Fund of China (11775038, 12047564)
文摘The shadow and observation intensity of a black hole surrounded by a thin spherical accretion in the Randall–Sundrum brane world model are investigated.The bulk metric depends on the tidal charge parameter,q,and deformation parameter,C.It reduces to the metric that possesses similar form with the Reissner–Nordström metric if C=0.It is shown that the radius of the photon sphere of this black hole depends only on the tidal charge parameter.The radius of the photon sphere decreases with higher q.The observation intensity is mainly influenced by the tidal charge parameter,q,and the deformation parameter,C,is of secondary importance.In the optical observation,the black holes appear brighter with higher q or lower C.
基金Supported by Sichuan Science and Technology Program(2023NSFSC1352)the starting fund of China West Normal University(20E069,20A013,22kA005)。
文摘We investigated the shadows and optical appearances of a new type of regular black holes(BHs)with a Minkowski core under various spherical accretion scenarios.These BHs are constructed by modifying the Newtonian potential based on the minimum observable length in the Generalized Uncertainty Principle(GUP).They correspond one-to-one with traditional regular BHs featuring a de-Sitter(dS)core(such as Bardeen/Hayward BHs),characterized by a quantum gravity effect parameter(α_(0))and spacetime deformation factor(n).We found that the characteristic parameters give rise to some novel observable features.For these new BHs,both the shadow and photon sphere radii decrease with the increase in α_(0),while the observed specific intensity increases.Conversely,as n increases,the shadow and photon sphere radii increase,while the observed specific intensity decreases.Under different spherical accretion scenarios,the shadows and photon sphere radii remain identical;however,the observed specific intensity is greater under static spherical accretion than under infalling spherical accretion.Additionally,we found that these regular BHs with different cores exhibit variations in shadows and optical appearances,particularly under static spherical accretion.Compared with Bardeen BH,the new BHs exhibit a lower observed specific intensity,a dimmer photon ring,and smaller shadow and photon sphere radii.Larger values of α_(0) lead to more significant differences,and a similar trend was also observed when comparing with Hayward BH.Under infalling spherical accretion,the regular BHs with different cores exhibit only slight differences in observed specific intensity,which become more evident when α_(0) is relatively large.This suggests that the unique spacetime features of these regular BHs with different cores can be distinguished through astronomical observation.
