ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 44,Issue 8,2018 Table of Contents
2018, 44(8):985-997.
DOI: 10.7519/j.issn.1000-0526.2018.08.001
Abstract:
Snow cover plays a significant role in climate change and hydrological cycle due to its specific properties, regulating energy and water exchange for atmosphere and land surface. The quality of the forcing data has a great influence on the result of model simulation. This paper adopts CLDAS and CLDASPrcp data driving on Noah 3.6 land surface model to simulate snow variables, and assesses snow cover fraction (SCF), snow depth (SD), the snow water equivalent (SWE) in major snow areas, such as Northeast China, Xinjiang and Tibetan Plateau Region. The result shows that CLDASPrcp can improve snow simulation in the winter, removes poor snow simulation due to underestimating precipitation of CLDAS. Model result of Northeast China is the most consistent with observations, CORR of SCF, SD and SWE are 0.42, 0.78 and 0.93 respectively. The improvement of snow water equivalent is most obvious, RMSE and BIAS are reduced by 54.8% and 83.1% respectively, while CORR is increased by 0.47. Thus, CLDASPrcp not only has better simulation capability but also reflects the extreme snow enevnts.
Snow cover plays a significant role in climate change and hydrological cycle due to its specific properties, regulating energy and water exchange for atmosphere and land surface. The quality of the forcing data has a great influence on the result of model simulation. This paper adopts CLDAS and CLDASPrcp data driving on Noah 3.6 land surface model to simulate snow variables, and assesses snow cover fraction (SCF), snow depth (SD), the snow water equivalent (SWE) in major snow areas, such as Northeast China, Xinjiang and Tibetan Plateau Region. The result shows that CLDASPrcp can improve snow simulation in the winter, removes poor snow simulation due to underestimating precipitation of CLDAS. Model result of Northeast China is the most consistent with observations, CORR of SCF, SD and SWE are 0.42, 0.78 and 0.93 respectively. The improvement of snow water equivalent is most obvious, RMSE and BIAS are reduced by 54.8% and 83.1% respectively, while CORR is increased by 0.47. Thus, CLDASPrcp not only has better simulation capability but also reflects the extreme snow enevnts.
2018, 44(8):998-1008.
DOI: 10.7519/j.issn.1000-0526.2018.08.002
Abstract:
No.1513 Typhoon Soudelor is simulated by using the GRAPES_Meso model, and the spatiotemporal evolution of the cloud system during the three stages of typhoon generation, maturity and landfall is analyzed. The results show that: (1) The process of Typhoon Soudelor from generation, maturity to landfall, weakening and dissipation is reproduced well with both the track and the trend of typhoon intensity in the simulation, which are close to observation. (2) In the development stage, the typhoon eye is blurred. The overall distribution of typhoon cloud system is well simulated, but the height of cloud top is lower than observation. (3) In the mature stage, there is a clear funnelshaped eye in the center of “Soudelor” cloud system. Cloud develops more strongly and presents structure of concentric eyewalls in the west of typhoon. The height of the simulated cloud top is lower than the observation. (4) The intensity of “Soudelor” is weakened rapidly after landfall. The eye is no longer obvious. The ability of the model to represent the detailed structure of Typhoon “Soudelor” after landfall is poor. (5) In general, the whole range of the cloud system of “Soudelor” is well simulated by GRAPES_Meso model. The simulated results in the first two stages are better than that in the postlanding stage. In a word, improving the cloud amount scheme in GRAPES model might help simulate typhoon cloud system.
No.1513 Typhoon Soudelor is simulated by using the GRAPES_Meso model, and the spatiotemporal evolution of the cloud system during the three stages of typhoon generation, maturity and landfall is analyzed. The results show that: (1) The process of Typhoon Soudelor from generation, maturity to landfall, weakening and dissipation is reproduced well with both the track and the trend of typhoon intensity in the simulation, which are close to observation. (2) In the development stage, the typhoon eye is blurred. The overall distribution of typhoon cloud system is well simulated, but the height of cloud top is lower than observation. (3) In the mature stage, there is a clear funnelshaped eye in the center of “Soudelor” cloud system. Cloud develops more strongly and presents structure of concentric eyewalls in the west of typhoon. The height of the simulated cloud top is lower than the observation. (4) The intensity of “Soudelor” is weakened rapidly after landfall. The eye is no longer obvious. The ability of the model to represent the detailed structure of Typhoon “Soudelor” after landfall is poor. (5) In general, the whole range of the cloud system of “Soudelor” is well simulated by GRAPES_Meso model. The simulated results in the first two stages are better than that in the postlanding stage. In a word, improving the cloud amount scheme in GRAPES model might help simulate typhoon cloud system.
2018, 44(8):1009-1019.
DOI: 10.7519/j.issn.1000-0526.2018.08.003
Abstract:
Model forecast performance and forewarning service validity of disastrous high wind have been among the chief concerns in industrial meteorological services. In view of these concerns, evaluation of the powergridsystemoriented meteorological forewarning for a high wind event was chosen as an example in order to demonstrate the applicability of Method for Objectbased Diagnostic Evaluation (MODE) for high wind events. Through the determination of the MODE crucial parameters and the object matching process, we found that (1) convolution radius, pairwise attributes weight and matching threshold are crucial to the identification of interest objects and the objectivity of error analysis. As a result, comprehensive considerations should be paid to the spatial resolution of forecast/observation grid data and userspecified spatial and temporal error redundancy. (2) General forecast performance can be depicted quantitatively by MODE, including the deviation of high wind location, range extent and temporal phase, so as to detect the area of false alarm and missing report every hour, and assess the forecast performance of moving speed and life cycle of high wind objects.
Model forecast performance and forewarning service validity of disastrous high wind have been among the chief concerns in industrial meteorological services. In view of these concerns, evaluation of the powergridsystemoriented meteorological forewarning for a high wind event was chosen as an example in order to demonstrate the applicability of Method for Objectbased Diagnostic Evaluation (MODE) for high wind events. Through the determination of the MODE crucial parameters and the object matching process, we found that (1) convolution radius, pairwise attributes weight and matching threshold are crucial to the identification of interest objects and the objectivity of error analysis. As a result, comprehensive considerations should be paid to the spatial resolution of forecast/observation grid data and userspecified spatial and temporal error redundancy. (2) General forecast performance can be depicted quantitatively by MODE, including the deviation of high wind location, range extent and temporal phase, so as to detect the area of false alarm and missing report every hour, and assess the forecast performance of moving speed and life cycle of high wind objects.
2018, 44(8):1020-1032.
DOI: 10.7519/j.issn.1000-0526.2018.08.004
Abstract:
With the development of the weather forecast modernization, forecasters are facing challenges brought by meteorological data explosion, the increasing demand of the service front end as well as the wide use of objective forecasting technology. Traditional quantitative precipitation forecast (QPF) technology, which is mainly based on manually plotting precipitation areas, can no longer assist forecasters to demonstrate added value at higher levels. To support the forecasters’ central role in the QPF procedure, a subjective and objective QPF blender was designed and developed. This platform helps forecasters to take control of the whole process of numerical forecast from the following five aspects: selection from mass forecast data, integration of multisource QPF, adjustment and correction of QPF, grid processing and service product production. The intelligence of the platform is secured by the development of a number of key supporting techniques, including multimodel QPF dataset construction technology, multimodel QPF integration technology, QPF field adjustment and correction techniques and gridded QPF postprocessing technology. Based on MICAPS4, the main functions of this QPF platform has been realized. The “QPF Master Blender 1.0” version was released and put into operation in May 2017, which has obtained good feedback and effectiveness. By the end of this paper, the future development of the platform is prospected, including the development of numerical model verification tools to support forecasters to make the best judgments, and research on the fusion technologies of multiscale model information.
With the development of the weather forecast modernization, forecasters are facing challenges brought by meteorological data explosion, the increasing demand of the service front end as well as the wide use of objective forecasting technology. Traditional quantitative precipitation forecast (QPF) technology, which is mainly based on manually plotting precipitation areas, can no longer assist forecasters to demonstrate added value at higher levels. To support the forecasters’ central role in the QPF procedure, a subjective and objective QPF blender was designed and developed. This platform helps forecasters to take control of the whole process of numerical forecast from the following five aspects: selection from mass forecast data, integration of multisource QPF, adjustment and correction of QPF, grid processing and service product production. The intelligence of the platform is secured by the development of a number of key supporting techniques, including multimodel QPF dataset construction technology, multimodel QPF integration technology, QPF field adjustment and correction techniques and gridded QPF postprocessing technology. Based on MICAPS4, the main functions of this QPF platform has been realized. The “QPF Master Blender 1.0” version was released and put into operation in May 2017, which has obtained good feedback and effectiveness. By the end of this paper, the future development of the platform is prospected, including the development of numerical model verification tools to support forecasters to make the best judgments, and research on the fusion technologies of multiscale model information.
5 Analysis of Conceptual Models and Ambient Parameter of ShortTime Severe Rainfall in South Xinjiang
2018, 44(8):1033-1041.
DOI: 10.7519/j.issn.1000-0526.2018.08.005
Abstract:
The spatiotemporal distribution of shorttime severe rainfall with different intensities was analyzed by using the hourly precipitation data of automatic weather station and regional automatic weather station, the NCEP/NCAR 1°×1° reanalysis data and the sounding data during 2010-2016. It is concluded that the weather pattern of the shorttime severe rainfall events in South Xinjiang has seasonal and regional characteristics obviously. Based on the characteristics of the environmental background of typical shorttime severe rainfall, three conceptual models of shorttime severe rainfall were established: Central Asia lowtrough (vortex) type, Siberian lowtrough (vortex) type and westerly shortwave type. The ambient background of the shorttime severe rainfall events in South Xinjiang was analyzed by the temperature and humidity profiles of seven sounding stations, ground dew point temperature, T850-T500, T700-T500, convective available potential energy (CAPE), convective inhibition (CIN), uplift condensation height, 0-6 km vertical wind shear etc. For shorttime severe rainfall Type Ⅰ (whole layer wet), shorttime severe rainfall Type Ⅱ (under the wet dry) and shorttime severe rainfall Type Ⅲ (upper dry wet), before the occurrence, there are abundant atmospheric water vapor, a certain CAPE obvious vertical wind shear as well as low 0℃ layer height, thick warmth cloud thickness and other characteristics. The appropriate CIN is favorable for the accumulation and explosion of the convective unstable energy, promoting the occurrence of shorttime severe rainfall. For the shorttime severe rainfall Type Ⅳ (dry adiabatic), the atmospheric stratification is relatively dry, and the T850-T500 and T700-T500 are relatively high. The Type Ⅰ (low vertex) and Type Ⅱ (low trough) are the main types of shorttime severe rainfall events in South Xinjiang which are often seen in the central and western parts of South Xinjiang, from mid summer to the end of summer, due to the influence of the Siberian lowvalue system (low vortex, low trough) type and lowvalue system in Central Asia (low vortex and low trough) type in the middle and southern regions of the southern part of China.
The spatiotemporal distribution of shorttime severe rainfall with different intensities was analyzed by using the hourly precipitation data of automatic weather station and regional automatic weather station, the NCEP/NCAR 1°×1° reanalysis data and the sounding data during 2010-2016. It is concluded that the weather pattern of the shorttime severe rainfall events in South Xinjiang has seasonal and regional characteristics obviously. Based on the characteristics of the environmental background of typical shorttime severe rainfall, three conceptual models of shorttime severe rainfall were established: Central Asia lowtrough (vortex) type, Siberian lowtrough (vortex) type and westerly shortwave type. The ambient background of the shorttime severe rainfall events in South Xinjiang was analyzed by the temperature and humidity profiles of seven sounding stations, ground dew point temperature, T850-T500, T700-T500, convective available potential energy (CAPE), convective inhibition (CIN), uplift condensation height, 0-6 km vertical wind shear etc. For shorttime severe rainfall Type Ⅰ (whole layer wet), shorttime severe rainfall Type Ⅱ (under the wet dry) and shorttime severe rainfall Type Ⅲ (upper dry wet), before the occurrence, there are abundant atmospheric water vapor, a certain CAPE obvious vertical wind shear as well as low 0℃ layer height, thick warmth cloud thickness and other characteristics. The appropriate CIN is favorable for the accumulation and explosion of the convective unstable energy, promoting the occurrence of shorttime severe rainfall. For the shorttime severe rainfall Type Ⅳ (dry adiabatic), the atmospheric stratification is relatively dry, and the T850-T500 and T700-T500 are relatively high. The Type Ⅰ (low vertex) and Type Ⅱ (low trough) are the main types of shorttime severe rainfall events in South Xinjiang which are often seen in the central and western parts of South Xinjiang, from mid summer to the end of summer, due to the influence of the Siberian lowvalue system (low vortex, low trough) type and lowvalue system in Central Asia (low vortex and low trough) type in the middle and southern regions of the southern part of China.
2018, 44(8):1042-1050.
DOI: 10.7519/j.issn.1000-0526.2018.08.006
Abstract:
Based on the hourly and daily precipitation data of national meteorological stations in Southwest China, the climatic characteristics of shorttime severe precipitation are analyzed. In addition, the variation trend of shorttime severe precipitation and severe rainstorms surpassing 90 percentile are analyzed as well. The results show that the shorttime severe precipitation over Southwest China mainly occurs from April to October. The three regions where shorttime severe precipitations are seen most frequently are located in the southeast of Guizhou Province, the southwest of Sichuan Basin, and the southeast of Yunnan Province, respectively, with average frequency is 5-6 times annually. Generally, the intensity is 20-30 mm·h-1, with the highest proportion of more than 30 mm·h-1 in Guizhou. The highest intensity occurs in the western edge of Sichuan Basin where the intensity is over 80 mm·h-1. The extreme hourly precipitation is 123.1 mm·h-1. Moreover, the nocturnal feature of the shorttime severe precipitations is evident and the wee hours around 02:00 am is the summit period. The longterm trend of severe precipitation and rainstorm in Southwest China for the period of 1981-2010 indicates that the frequency of the heavy shorttime severe precipitations is increasing and the intensity becomes enhanced. For severe rainstorms, the trend is not evidently changed.
Based on the hourly and daily precipitation data of national meteorological stations in Southwest China, the climatic characteristics of shorttime severe precipitation are analyzed. In addition, the variation trend of shorttime severe precipitation and severe rainstorms surpassing 90 percentile are analyzed as well. The results show that the shorttime severe precipitation over Southwest China mainly occurs from April to October. The three regions where shorttime severe precipitations are seen most frequently are located in the southeast of Guizhou Province, the southwest of Sichuan Basin, and the southeast of Yunnan Province, respectively, with average frequency is 5-6 times annually. Generally, the intensity is 20-30 mm·h-1, with the highest proportion of more than 30 mm·h-1 in Guizhou. The highest intensity occurs in the western edge of Sichuan Basin where the intensity is over 80 mm·h-1. The extreme hourly precipitation is 123.1 mm·h-1. Moreover, the nocturnal feature of the shorttime severe precipitations is evident and the wee hours around 02:00 am is the summit period. The longterm trend of severe precipitation and rainstorm in Southwest China for the period of 1981-2010 indicates that the frequency of the heavy shorttime severe precipitations is increasing and the intensity becomes enhanced. For severe rainstorms, the trend is not evidently changed.
2018, 44(8):1051-1062.
DOI: 10.7519/j.issn.1000-0526.2018.08.007
Abstract:
Three typical long duration torrential rain events in Liaoning Province are selected. Based on the data of NCEP/NCAR 1°×1° reanalysis, FY2E black body temperature (TBB for short), Doppler weather radar and automatic weather station, the representative characteristics of changes in precipitation observation, the background of synoptic situation, the satellite infrared cloud image, the structure and intensity of radar echoes are analyzed. The results show that long duration torrential rain that occurs in Liaoning Province are caused by longterm continuous interaction of warm and cold air masses in certain areas under the background of largescale synoptic environment conducive to torrential rain. This type of torrential rain has two types of characteristics. One is little change in precipitation intensity, and no obvious periodical characteristics of torrential rain, and the another is strong change in precipitation intensity, and obvious periodical characteristics of torrential rain. The general convective clouds, warm clouds and deep convective clouds can cause torrential rain, in which the TBB of general convective clouds varies between -47℃ and -36℃, the TBB of warm clouds is between -8℃ and 3℃, the TBB of deep convective clouds is between -68℃ and -50℃, and torrential rain occurs in the center of the low TBB to the large temperature gradient zone on one side. This type of torrential rain shows that the upper stream radar echoes continuously move into the downstream to form a “train effect”, the locally generated and intensified strong echoes and the strong radar echoes generated from the upstream maintain intensities and step into the downstream. The hourly average radar echo intensity and its change have a good indication of precipitation intensity and its trend. In particular, special attention should be paid to the analysis and monitoring of warm cloud which contributes to torrential rain in the west side of the subtropical high, high energy and high humidity, low condensation height, the whole almost saturated layer, and the trigger conditions of local topographic uplift.
Three typical long duration torrential rain events in Liaoning Province are selected. Based on the data of NCEP/NCAR 1°×1° reanalysis, FY2E black body temperature (TBB for short), Doppler weather radar and automatic weather station, the representative characteristics of changes in precipitation observation, the background of synoptic situation, the satellite infrared cloud image, the structure and intensity of radar echoes are analyzed. The results show that long duration torrential rain that occurs in Liaoning Province are caused by longterm continuous interaction of warm and cold air masses in certain areas under the background of largescale synoptic environment conducive to torrential rain. This type of torrential rain has two types of characteristics. One is little change in precipitation intensity, and no obvious periodical characteristics of torrential rain, and the another is strong change in precipitation intensity, and obvious periodical characteristics of torrential rain. The general convective clouds, warm clouds and deep convective clouds can cause torrential rain, in which the TBB of general convective clouds varies between -47℃ and -36℃, the TBB of warm clouds is between -8℃ and 3℃, the TBB of deep convective clouds is between -68℃ and -50℃, and torrential rain occurs in the center of the low TBB to the large temperature gradient zone on one side. This type of torrential rain shows that the upper stream radar echoes continuously move into the downstream to form a “train effect”, the locally generated and intensified strong echoes and the strong radar echoes generated from the upstream maintain intensities and step into the downstream. The hourly average radar echo intensity and its change have a good indication of precipitation intensity and its trend. In particular, special attention should be paid to the analysis and monitoring of warm cloud which contributes to torrential rain in the west side of the subtropical high, high energy and high humidity, low condensation height, the whole almost saturated layer, and the trigger conditions of local topographic uplift.
2018, 44(8):1063-1072.
DOI: 10.7519/j.issn.1000-0526.2018.08.008
Abstract:
Based on the hourly precipitation data in Shandong Province during 1961-2012 from 74 weather stations, spatiotemporal distribution characteristics of shortduration and longduration precipitation events in flood season (May-September) in Shandong are analyzed. The results show that: (1) the increase of process precipitation and process duration makes the total precipitation amount in Shandong in flood season increase slightly. The frequency of continuous precipitation processes, the increase of process precipitation, and the increase of process duration make the greatest contribution to the increase of total precipitation. (2) The total precipitation of shortduration is the most in the mountain areas of the central and southeast parts of Shandong while the persistent total precipitation is the most in the southeast coast of Shandong and the eastern part of the peninsula. The shortduration precipitation and the average rainfall intensity are the largest from southeast Shandong to Dezhou region, and, in contrast, the sustained rainfall and the average rainfall intensity are the largest in the eastern part of the peninsula and the southeast part of Shandong. (3) The shortduration rain intensity peak is greater in the surrounding areas of the mountain area in central Shandong, and the sustained rain intensity peak is higher in the southern and southeastern parts of Shandong as well as the eastern part of the peninsula. (4) The shortduration precipitation in the mountain area of central and southern parts of Shandong and some places of the peninsula generally occur from 13:00 BT to 18:00 BT in the afternoon. Around the mountain area in central Shandong and the coastal area of the peninsula, it rains mostly at night and also the beginning time of the continuous precipitation appears at night mostly.
Based on the hourly precipitation data in Shandong Province during 1961-2012 from 74 weather stations, spatiotemporal distribution characteristics of shortduration and longduration precipitation events in flood season (May-September) in Shandong are analyzed. The results show that: (1) the increase of process precipitation and process duration makes the total precipitation amount in Shandong in flood season increase slightly. The frequency of continuous precipitation processes, the increase of process precipitation, and the increase of process duration make the greatest contribution to the increase of total precipitation. (2) The total precipitation of shortduration is the most in the mountain areas of the central and southeast parts of Shandong while the persistent total precipitation is the most in the southeast coast of Shandong and the eastern part of the peninsula. The shortduration precipitation and the average rainfall intensity are the largest from southeast Shandong to Dezhou region, and, in contrast, the sustained rainfall and the average rainfall intensity are the largest in the eastern part of the peninsula and the southeast part of Shandong. (3) The shortduration rain intensity peak is greater in the surrounding areas of the mountain area in central Shandong, and the sustained rain intensity peak is higher in the southern and southeastern parts of Shandong as well as the eastern part of the peninsula. (4) The shortduration precipitation in the mountain area of central and southern parts of Shandong and some places of the peninsula generally occur from 13:00 BT to 18:00 BT in the afternoon. Around the mountain area in central Shandong and the coastal area of the peninsula, it rains mostly at night and also the beginning time of the continuous precipitation appears at night mostly.
2018, 44(8):1073-1081.
DOI: 10.7519/j.issn.1000-0526.2018.08.009
Abstract:
Based on the monthly rainfall of 170 stations over Huaihe River Basin, NCEP reanalysis data and ERSST sea surface temperature data, the stability of the variation characteristics of the relationship between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin is studied by using sliding correlation, composition analysis etc. It shows that the relationship between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin is not stable, the 11year slide correlation probably mutates in 1979.It is significant negative correlation between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin during 1961-1979, and it is normal correlation during 1980-1992, but it is significant positive values during 1993-2015. The influences of El Ni〖AKn~D〗o/La Ni〖AKn~D〗a on the precipitation over the Huaihe River Basin during two obvious correlation periods are mainly discussed. The influences of El Ni〖AKn~D〗o/La Ni〖AKn~D〗a on the precipitation over the basin during 1961-1979 and 1993-2015 are on the opposite. And the El Ni〖AKn~D〗o/La Ni〖AKn~D〗a events during 1993-2015 as a predictor of the summer precipitation over the Huaihe River Basin are weaker than the El Ni〖AKn~D〗o/La Ni〖AKn~D〗a events during 1961-1979. The influence of El Ni〖AKn~D〗o events on the precipitation over Huaihe River Basin is obvious, but the influence of La Ni〖AKn~D〗a events is not obvious, and the influences of both are asymmetrical. The distribution of Asian atmospheric circulation in El Ni〖AKn~D〗o developing (decaying) summer during 1961-1979 is conductive to the north and south air convergence (divergence) over the Huaihe River Basin, which makes the precipitation over the basin more (less) than normal. While the El Ni〖AKn~D〗o events are on the opposite during 1993-2015.
Based on the monthly rainfall of 170 stations over Huaihe River Basin, NCEP reanalysis data and ERSST sea surface temperature data, the stability of the variation characteristics of the relationship between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin is studied by using sliding correlation, composition analysis etc. It shows that the relationship between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin is not stable, the 11year slide correlation probably mutates in 1979.It is significant negative correlation between El Ni〖AKn~D〗o/La Ni〖AKn~D〗a and the summer rainfall over Huaihe River Basin during 1961-1979, and it is normal correlation during 1980-1992, but it is significant positive values during 1993-2015. The influences of El Ni〖AKn~D〗o/La Ni〖AKn~D〗a on the precipitation over the Huaihe River Basin during two obvious correlation periods are mainly discussed. The influences of El Ni〖AKn~D〗o/La Ni〖AKn~D〗a on the precipitation over the basin during 1961-1979 and 1993-2015 are on the opposite. And the El Ni〖AKn~D〗o/La Ni〖AKn~D〗a events during 1993-2015 as a predictor of the summer precipitation over the Huaihe River Basin are weaker than the El Ni〖AKn~D〗o/La Ni〖AKn~D〗a events during 1961-1979. The influence of El Ni〖AKn~D〗o events on the precipitation over Huaihe River Basin is obvious, but the influence of La Ni〖AKn~D〗a events is not obvious, and the influences of both are asymmetrical. The distribution of Asian atmospheric circulation in El Ni〖AKn~D〗o developing (decaying) summer during 1961-1979 is conductive to the north and south air convergence (divergence) over the Huaihe River Basin, which makes the precipitation over the basin more (less) than normal. While the El Ni〖AKn~D〗o events are on the opposite during 1993-2015.
2018, 44(8):1082-1093.
DOI: 10.7519/j.issn.1000-0526.2018.08.010
Abstract:
In order to better understand the quality of precipitable water retrieved from FY2 satellite data (FY2/PW), the comparison research is done in this study between the FY2/PW and GPS/PW collected in 2012 and 2015. The results indicate that: (1) the two datasets are highly correlated at three stations (Beijing,Wuhan and Haikou) with correlation coefficients more than 0.67 in summer. The values of PW RMSE and monthly mean bias are less in summer than in winter. The bias and RMSE of PW for four seasons exhibited a pronounced diurnal variation in Beijing and Wuhan. (2) When the value of GPS/PW is greater than 20 mm, FY2/PW agrees well with GPS/PW at Beijing, Wuhan, Haikou and Lhasa Stations. On the other hand, when the value of GPS/PW is less than 20 mm, the absolute values of PW bias and RMSE quickly increase with the decrease of GPS/PW. All the results show that the accuracy of FY2/PW tends to be high in summer, but the retrieval results need some improvement in the conditons of low atmospheric humidity, winter and night.
In order to better understand the quality of precipitable water retrieved from FY2 satellite data (FY2/PW), the comparison research is done in this study between the FY2/PW and GPS/PW collected in 2012 and 2015. The results indicate that: (1) the two datasets are highly correlated at three stations (Beijing,Wuhan and Haikou) with correlation coefficients more than 0.67 in summer. The values of PW RMSE and monthly mean bias are less in summer than in winter. The bias and RMSE of PW for four seasons exhibited a pronounced diurnal variation in Beijing and Wuhan. (2) When the value of GPS/PW is greater than 20 mm, FY2/PW agrees well with GPS/PW at Beijing, Wuhan, Haikou and Lhasa Stations. On the other hand, when the value of GPS/PW is less than 20 mm, the absolute values of PW bias and RMSE quickly increase with the decrease of GPS/PW. All the results show that the accuracy of FY2/PW tends to be high in summer, but the retrieval results need some improvement in the conditons of low atmospheric humidity, winter and night.
2018, 44(8):1094-1103.
DOI: 10.7519/j.issn.1000-0526.2018.08.011
Abstract:
The observation experiments of balloon borne radiosonde rising and parachute carrying radiosonde descending were carried out, and the methods for evaluating the temperature, relative humidity and pressure of dropsonde were established. The results showed that the accuracy of temperature and pressure of Beidou dropsonde ascending is quite similar to that of RS92, and the relative humidity is worse than the double heating humidity sensor of RS92. The accuracy of temperature of Beidou dropsonde descending is almost equivalent to that of RS92 and the pressure has some influences on the positioning due to the fast falling, resulting in greater pressure error. The error of relative humidity is basically within 5%, meeting the requirements of WMO measurements. Beidou and RS92 are matched with wind profile radar in time and space. On the rising phase, the accuracy of wind direction of Beidou is worse than that of RS92, and the accuracy of wind speed is significantly greater than that of RS92. In addition, the results showed that the 2-time observation mode of the ball-loaded descent sounding has good application prospect and could realize the densifying observation in space and time of upper-air station network.
The observation experiments of balloon borne radiosonde rising and parachute carrying radiosonde descending were carried out, and the methods for evaluating the temperature, relative humidity and pressure of dropsonde were established. The results showed that the accuracy of temperature and pressure of Beidou dropsonde ascending is quite similar to that of RS92, and the relative humidity is worse than the double heating humidity sensor of RS92. The accuracy of temperature of Beidou dropsonde descending is almost equivalent to that of RS92 and the pressure has some influences on the positioning due to the fast falling, resulting in greater pressure error. The error of relative humidity is basically within 5%, meeting the requirements of WMO measurements. Beidou and RS92 are matched with wind profile radar in time and space. On the rising phase, the accuracy of wind direction of Beidou is worse than that of RS92, and the accuracy of wind speed is significantly greater than that of RS92. In addition, the results showed that the 2-time observation mode of the ball-loaded descent sounding has good application prospect and could realize the densifying observation in space and time of upper-air station network.
2018, 44(8):1104-1109.
DOI: 10.7519/j.issn.1000-0526.2018.08.012
Abstract:
The mediumrange forecasts calculated by the T369, ECMWF and Japan (JP) models are verified. The results show that all of the three models could well predict the variation and adjustment of the atmospheric circulation over middle and high latitudes in Eurasia, and among them the ECMWF model performs the best, which has a good performance in predicting activity of western Pacific subtropical high. All the three models perform well in predicting the transition of temperature at 850 hPa, but they tend to overestimated the temperature over the north and south of China. For southern China, three models have smaller biases in temperature prediction than for northern China, and the ECMWF model has better performance than T639 and Japan model. As far as the sandstorm precess seen in 27-29 March, the ECMWF model is more effective than Japan and T639 model in mediumrange forecasting of the surface high pressure system which incurred the sandstorm weather this time.
The mediumrange forecasts calculated by the T369, ECMWF and Japan (JP) models are verified. The results show that all of the three models could well predict the variation and adjustment of the atmospheric circulation over middle and high latitudes in Eurasia, and among them the ECMWF model performs the best, which has a good performance in predicting activity of western Pacific subtropical high. All the three models perform well in predicting the transition of temperature at 850 hPa, but they tend to overestimated the temperature over the north and south of China. For southern China, three models have smaller biases in temperature prediction than for northern China, and the ECMWF model has better performance than T639 and Japan model. As far as the sandstorm precess seen in 27-29 March, the ECMWF model is more effective than Japan and T639 model in mediumrange forecasting of the surface high pressure system which incurred the sandstorm weather this time.
2018, 44(8):1110-1116.
DOI: 10.7519/j.issn.1000-0526.2018.08.013
Abstract:
The main characteristics of the general atmospheric circulation in May 2018 are as follows. Two polar vortex centers were in the Northern Hemisphere and stronger than usual. The circulation at middlehigh latitudes of the Eurasian showed a threewave pattern, and the degree of meridionality was lower than normal. The strength of Western Pacific subtropical high was stronger than the climatological normal, and the Bay of Bengal trough is slightly weaker than normal. The monthly mean temperature was 17.1℃, higher than normal (16.2℃) by 0.9℃. The monthly mean precipitation amount was 73.1 mm, more than normal by 5.2%. Seven severe rainfall events occurred in southern China this month, and several provinces were attacked by severe thunderstorms and hail disaster. In addition, severe droughts took place in the Northeast China, which was weakened in the later part of month. Hightemperature weather began to persist in southern China from the middle of May, and two dust weather events happened in northern China.
The main characteristics of the general atmospheric circulation in May 2018 are as follows. Two polar vortex centers were in the Northern Hemisphere and stronger than usual. The circulation at middlehigh latitudes of the Eurasian showed a threewave pattern, and the degree of meridionality was lower than normal. The strength of Western Pacific subtropical high was stronger than the climatological normal, and the Bay of Bengal trough is slightly weaker than normal. The monthly mean temperature was 17.1℃, higher than normal (16.2℃) by 0.9℃. The monthly mean precipitation amount was 73.1 mm, more than normal by 5.2%. Seven severe rainfall events occurred in southern China this month, and several provinces were attacked by severe thunderstorms and hail disaster. In addition, severe droughts took place in the Northeast China, which was weakened in the later part of month. Hightemperature weather began to persist in southern China from the middle of May, and two dust weather events happened in northern China.
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ISSN:1000-0526 CN:11-2282/P