ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 36,Issue 4,2010 Table of Contents
2010, 36(4):1-6.
DOI: 10.7519/j.issn.1000-0526.2010.4.001
Abstract:
This survey paper is devoted to describe the generalized equilibrium feedback analysis (GEFA). In the framework of the equilibrium feedback analysis (EFA), Liu et al. (2008)［2］ developed a generalized EFA (GEFA) method to separate each ocean’s influence to the atmosphere. Furthermore, the GEFA also helps to understand different substrate’s influence to the atmosphere. In brief, the GEFA is a useful statistical method in the study of the oceanlandatmospheric interaction.
This survey paper is devoted to describe the generalized equilibrium feedback analysis (GEFA). In the framework of the equilibrium feedback analysis (EFA), Liu et al. (2008)［2］ developed a generalized EFA (GEFA) method to separate each ocean’s influence to the atmosphere. Furthermore, the GEFA also helps to understand different substrate’s influence to the atmosphere. In brief, the GEFA is a useful statistical method in the study of the oceanlandatmospheric interaction.
2010, 36(4):7-15.
DOI: 10.7519/j.issn.1000-0526.2010.4.002
Abstract:
Using the NCEP reanalysis data, based on the comparison analysis, the general circulation and impacting systems of plateau vortex moving out of the plateau or not in summer from 2000 to 2004 are analyzed. The research indicates that at 500 hPa level, the circulation background of the plateau vortex moving out of the plateau abbreviated as PV (out), including the trough in the Balkhash Lake, East Asian major trough and high pressure ridge at Mongolia is stronger compared to the circulation background of plateau vortex moving not out of the plateau abbreviated as PV (not out), that is, the circulation background of PV (out) has the meridional circulation increased. And the Pacific subtropical high westward extension is significant in the circulation background of PV (out) compared with PV (not out). In the middle troposphere the warm advection is very important to the generation of the plateau vortex and vortex is apt to move eastward when there is a cold advection in Xinjiang. On the Tibeten Plateau, the positive vorticity advection in the middle troposphere is very important to the generation of the plateau vortex. The positive vorticity advection of PV (out) is weaker compared with it of PV (not out), and the vortex is apt to move eastward when there is a positive vorticity advection in Ordos Region. In the upper troposphere, the existence of South Asia high is beneficial to the generation of plateau vortex, and over PV (out), the strength of South Asia high is stronger than it of PV (not out).And when northeastern part of the Tibetan Plateau, the Sichuan Basin, Shanxi Province are located in the south side of the entrance of the upper jet stream, it is beneficial to plateau vortex to move eastward. Analysis of the similarities and differences between PV (out) and PV (not out) in the general circulation,the temperature advection and the vorticity advection could put forward the scientific basis to the prediction of PV(out) and PV (not out).
Using the NCEP reanalysis data, based on the comparison analysis, the general circulation and impacting systems of plateau vortex moving out of the plateau or not in summer from 2000 to 2004 are analyzed. The research indicates that at 500 hPa level, the circulation background of the plateau vortex moving out of the plateau abbreviated as PV (out), including the trough in the Balkhash Lake, East Asian major trough and high pressure ridge at Mongolia is stronger compared to the circulation background of plateau vortex moving not out of the plateau abbreviated as PV (not out), that is, the circulation background of PV (out) has the meridional circulation increased. And the Pacific subtropical high westward extension is significant in the circulation background of PV (out) compared with PV (not out). In the middle troposphere the warm advection is very important to the generation of the plateau vortex and vortex is apt to move eastward when there is a cold advection in Xinjiang. On the Tibeten Plateau, the positive vorticity advection in the middle troposphere is very important to the generation of the plateau vortex. The positive vorticity advection of PV (out) is weaker compared with it of PV (not out), and the vortex is apt to move eastward when there is a positive vorticity advection in Ordos Region. In the upper troposphere, the existence of South Asia high is beneficial to the generation of plateau vortex, and over PV (out), the strength of South Asia high is stronger than it of PV (not out).And when northeastern part of the Tibetan Plateau, the Sichuan Basin, Shanxi Province are located in the south side of the entrance of the upper jet stream, it is beneficial to plateau vortex to move eastward. Analysis of the similarities and differences between PV (out) and PV (not out) in the general circulation,the temperature advection and the vorticity advection could put forward the scientific basis to the prediction of PV(out) and PV (not out).
2010, 36(4):16-20.
DOI: 10.7519/j.issn.1000-0526.2010.4.003
Abstract:
Based on the observations of precipitation and visibility ranges from 1961 to 2005 at the top of the Wutai Mountain, the ratios between the precipitation amount at Wutai Mountain and at the nearby plain stations (Yuanping and Yangquan), together with the relation between visibility and aerosol concentration were analyzed to reveal the effect of aerosols on orographic precipitation. Over the Wutai Mountain region, visibility, together with precipitation and number of wet days have a significant decline. Precipitation amount and number of wet days at Wutaishan Station, which are much larger than those the plain stations. Further, the ratios of precipitation amount, and numbers of wet days and the days with precipitation less than 5 mm between Wutaishan Station and the contrast stations also have a significant decline, which has a significant correlation (p<0.05) with visibility. It can be speculated that declining visibility indicates enhancing aerosol concentration, which possibly suppresses orographic precipitation. Decreasing orographic precipitation results in declining water resources in mountain regions; if no precipitation gauges at the top of peaks, the precipitation monitoring network can not capture the effect of declining orographic rainfall on areal precipitation, which leads to an underestimation of the decrease in areal precipitation, as well as water resources.
Based on the observations of precipitation and visibility ranges from 1961 to 2005 at the top of the Wutai Mountain, the ratios between the precipitation amount at Wutai Mountain and at the nearby plain stations (Yuanping and Yangquan), together with the relation between visibility and aerosol concentration were analyzed to reveal the effect of aerosols on orographic precipitation. Over the Wutai Mountain region, visibility, together with precipitation and number of wet days have a significant decline. Precipitation amount and number of wet days at Wutaishan Station, which are much larger than those the plain stations. Further, the ratios of precipitation amount, and numbers of wet days and the days with precipitation less than 5 mm between Wutaishan Station and the contrast stations also have a significant decline, which has a significant correlation (p<0.05) with visibility. It can be speculated that declining visibility indicates enhancing aerosol concentration, which possibly suppresses orographic precipitation. Decreasing orographic precipitation results in declining water resources in mountain regions; if no precipitation gauges at the top of peaks, the precipitation monitoring network can not capture the effect of declining orographic rainfall on areal precipitation, which leads to an underestimation of the decrease in areal precipitation, as well as water resources.
2010, 36(4):21-26.
DOI: 10.7519/j.issn.1000-0526.2010.4.004
Abstract:
On July 22, 2008, a longlasting torrential rainfall envent occurred in Xiangfan ,Hubei Province. Its accumulated rainfall only for 9 hours was 301 mm, as much as 1/3 of the normal yearly rainfall, which was the strongest rainfall according to meteorological records of Xiangfan. The echo structure characteristics, mesoscale system activity and the topographic forcing were analyzed by the Doppler radar data. The results show as follows. （1） There are two echo systems affecting torrential rainfall of Xiangfan, one is the shear linebanded echo which maintains stably in northwestern Hubei, the other is the vortex echo with a spiralechobelt structure. Both together form a vortexband combined echo structure. In the conjunction area, convective echoes emerge and move to the north continually, resulting in the Xiangfan longlasting strong rainfall. （2） The Xiangfan rainstorm event has a close relationship to the established superlowlevel northeasterly jet, and the strong warmmoist southwesterly moving to the north. Because of the Wudang mountain’s barrier located in the west side of Xiangfan, the superLLJ turns to southeast, and forms the mesoscale cyclone convergence with the warmmoist southwesterly nearby the stationary front. The two stranded LLJs play a key role in sustaining convergence near Xiangfan.
On July 22, 2008, a longlasting torrential rainfall envent occurred in Xiangfan ,Hubei Province. Its accumulated rainfall only for 9 hours was 301 mm, as much as 1/3 of the normal yearly rainfall, which was the strongest rainfall according to meteorological records of Xiangfan. The echo structure characteristics, mesoscale system activity and the topographic forcing were analyzed by the Doppler radar data. The results show as follows. （1） There are two echo systems affecting torrential rainfall of Xiangfan, one is the shear linebanded echo which maintains stably in northwestern Hubei, the other is the vortex echo with a spiralechobelt structure. Both together form a vortexband combined echo structure. In the conjunction area, convective echoes emerge and move to the north continually, resulting in the Xiangfan longlasting strong rainfall. （2） The Xiangfan rainstorm event has a close relationship to the established superlowlevel northeasterly jet, and the strong warmmoist southwesterly moving to the north. Because of the Wudang mountain’s barrier located in the west side of Xiangfan, the superLLJ turns to southeast, and forms the mesoscale cyclone convergence with the warmmoist southwesterly nearby the stationary front. The two stranded LLJs play a key role in sustaining convergence near Xiangfan.
2010, 36(4):27-29.
DOI: 10.7519/j.issn.1000-0526.2010.4.005
Abstract:
In order to explore the impact of the mixed layer depth on the tropical cyclone (TC), some sensitivity tests have been conducted using a new coupled mesoscale oceanatmosphere model. The result shows that the initial mixed layer depth has great impacts on both the maximum intensity and the enhancement time of TC. Generally speaking, the initial mixed layer gets deeper, the maximum intensity becomes greater, and the enhancement time becomes longer. In addition, the relationship between TC and mixed layer depth is nonlinear. When the mixed layer depth is shallower, the TC intensity is more sensitive to its changes.
In order to explore the impact of the mixed layer depth on the tropical cyclone (TC), some sensitivity tests have been conducted using a new coupled mesoscale oceanatmosphere model. The result shows that the initial mixed layer depth has great impacts on both the maximum intensity and the enhancement time of TC. Generally speaking, the initial mixed layer gets deeper, the maximum intensity becomes greater, and the enhancement time becomes longer. In addition, the relationship between TC and mixed layer depth is nonlinear. When the mixed layer depth is shallower, the TC intensity is more sensitive to its changes.
2010, 36(4):30-36.
DOI: 10.7519/j.issn.1000-0526.2010.4.006
Abstract:
Based on NCEP 2.5°×2.5°reanalyzed data and daily observation data, the characteristics of climatic situation and influencing systems of 50 regional heavy snow events in Jiangxi from 1980 to 2008 were summarized and analyzed. The results show that: The heavy snow events in Jiangxi had a period of about 5 years. Before the 1990s, heavy snow events happened often and had large variations. Afterwards, the interannual variations tended to occur less frequently. As to the spatial variation, the frequency of heavy snow was characterized by the distribution of gradually reducing from the northwest to the southeast. During heavy snow periods, the blocking high and the frontal zone in midlow latitudes were extremely powerful. The 80% heavy snow events were associated with blocking high, most of which were Baikal Lake blocking highs. While 70% of the events were associated with the south branch trough. Most heavy snow events were associated with shear lines at 700 hPa. And there was significant southwest jet with an over 16 m·s-1axis at the south of it. Normally, the snowing region was 1-3 degrees in latitudes south of a cold shear line or at the neighborhood of a warm shear line. If there was a shear line at 850 hPa simultaneously, the snow would be heavier. The 98% of the events were accompanied by inversion layers in the troposphere. The vertical distribution of temperature was characterized by <1 ℃ at 1000 hPa, ≤-2 ℃ at 925-850 hPa and ≤0 ℃ at 700 hPa. Mostly, the surface cold air was from the middle area where an extremely strong Mongolia cold high offered a favorable condition for snowfall.
Based on NCEP 2.5°×2.5°reanalyzed data and daily observation data, the characteristics of climatic situation and influencing systems of 50 regional heavy snow events in Jiangxi from 1980 to 2008 were summarized and analyzed. The results show that: The heavy snow events in Jiangxi had a period of about 5 years. Before the 1990s, heavy snow events happened often and had large variations. Afterwards, the interannual variations tended to occur less frequently. As to the spatial variation, the frequency of heavy snow was characterized by the distribution of gradually reducing from the northwest to the southeast. During heavy snow periods, the blocking high and the frontal zone in midlow latitudes were extremely powerful. The 80% heavy snow events were associated with blocking high, most of which were Baikal Lake blocking highs. While 70% of the events were associated with the south branch trough. Most heavy snow events were associated with shear lines at 700 hPa. And there was significant southwest jet with an over 16 m·s-1axis at the south of it. Normally, the snowing region was 1-3 degrees in latitudes south of a cold shear line or at the neighborhood of a warm shear line. If there was a shear line at 850 hPa simultaneously, the snow would be heavier. The 98% of the events were accompanied by inversion layers in the troposphere. The vertical distribution of temperature was characterized by <1 ℃ at 1000 hPa, ≤-2 ℃ at 925-850 hPa and ≤0 ℃ at 700 hPa. Mostly, the surface cold air was from the middle area where an extremely strong Mongolia cold high offered a favorable condition for snowfall.
2010, 36(4):37-42.
DOI: 10.7519/j.issn.1000-0526.2010.4.007
Abstract:
Based on the NCEP reanalysis data of wind, humidity, vertical velocity and the surface observation data of Shenzhen, the main warming factors are explored under the influence of peripheral circulation of tropical cyclones. According to thermodynamic energy equation, the contribution rate of every warming factor is estimated. Results are indicated as follows: Nonadiabatic term is the basis of high temperature in Shenzhen; the warming proportion is 90.2%; and the warming rate is 0.83 ℃?h-1. If assuming the warming rate unchanged from 08:00 to 14:00, then temperature would increase by 5.0 ℃ from 08:00 to 14:00 caused by the nonadiabatic term. The second important reason for hightemperature includes the decrease of relative humidity, air sinking warming, and warm advection. Their respective proportions are 7.6%,3.8% and 7.0%,〖HJ〗 with a total of warming rate of 0.17 ℃?h-1. Temperature increases 1.12 ℃ from 08:00 to 14:00 caused by these 3 terms. Therefore the greatest contribution to high temperature is made by the nonadiabatic term including decrease of relative humidity. Smaller contribution is made by dry air adiabatic subsidence. Larger contribution is made by warm advection.
Based on the NCEP reanalysis data of wind, humidity, vertical velocity and the surface observation data of Shenzhen, the main warming factors are explored under the influence of peripheral circulation of tropical cyclones. According to thermodynamic energy equation, the contribution rate of every warming factor is estimated. Results are indicated as follows: Nonadiabatic term is the basis of high temperature in Shenzhen; the warming proportion is 90.2%; and the warming rate is 0.83 ℃?h-1. If assuming the warming rate unchanged from 08:00 to 14:00, then temperature would increase by 5.0 ℃ from 08:00 to 14:00 caused by the nonadiabatic term. The second important reason for hightemperature includes the decrease of relative humidity, air sinking warming, and warm advection. Their respective proportions are 7.6%,3.8% and 7.0%,〖HJ〗 with a total of warming rate of 0.17 ℃?h-1. Temperature increases 1.12 ℃ from 08:00 to 14:00 caused by these 3 terms. Therefore the greatest contribution to high temperature is made by the nonadiabatic term including decrease of relative humidity. Smaller contribution is made by dry air adiabatic subsidence. Larger contribution is made by warm advection.
2010, 36(4):43-50.
DOI: 10.7519/j.issn.1000-0526.2010.4.008
Abstract:
A relationship between cloudtop heights retrieved from combination of FY-2C/D geostationary satellite data and other observation data and radarderived echotops is investigated. Tens of thousands of samples from 20 precipitation cases caused by cumuliformstratiformmixed and stratiform clouds are evaluated. It shows that there is remarkably a positive correlation relationship between satellitederived cloudtopheight and radar echotop. It is likely that the relationship is hardly dependent upon combined reflectivity factor. Cloudtop heights mainly derived by FY-2 are more consistent with echo tops of less than 18 dBz reflectivity factor, compared with those of 18 dBz reflectivity factor because FY2 satellites and SAtyperadars have different observational and retrieval principles. Satellitederived cloudtopheight represents radiation characteristics of cloud droplets in the top of cumuliformstratiformmixed and stratiform clouds, and meanwhile radarretrieved echotop implies ability that larger precipitation particles attenuate electromagnetic waves of radars.
A relationship between cloudtop heights retrieved from combination of FY-2C/D geostationary satellite data and other observation data and radarderived echotops is investigated. Tens of thousands of samples from 20 precipitation cases caused by cumuliformstratiformmixed and stratiform clouds are evaluated. It shows that there is remarkably a positive correlation relationship between satellitederived cloudtopheight and radar echotop. It is likely that the relationship is hardly dependent upon combined reflectivity factor. Cloudtop heights mainly derived by FY-2 are more consistent with echo tops of less than 18 dBz reflectivity factor, compared with those of 18 dBz reflectivity factor because FY2 satellites and SAtyperadars have different observational and retrieval principles. Satellitederived cloudtopheight represents radiation characteristics of cloud droplets in the top of cumuliformstratiformmixed and stratiform clouds, and meanwhile radarretrieved echotop implies ability that larger precipitation particles attenuate electromagnetic waves of radars.
2010, 36(4):51-56.
DOI: 10.7519/j.issn.1000-0526.2010.4.009
Abstract:
Interannual and interdecadal variations of South Asia high (SAH) and the relation with the summer precipitation of China are studied by use of the NCEP/NCAR monthly mean reanalysis data and observational data at stations given by National Meteorological Center. It is found that all of the parameters of SAH except the ridge line position exist the remarkably interdecadal variations in summer. There is no significant partial correlation between the intensity and the east ridge point (ERP) of SAH when the area is stable. The simultaneous correlation shows that the significant positive correlation occurs between the location of the ERP of SAH and the summer rainfall of the YangtzeHuaihe River Basin (YHB) during 1979-2008, and this correlation has a big change through the sliding correlation analysis, turning from the negative correlation before the 1970s to the positive one. All these exhibit that the position of the ERP of SAH can be considered as a strong signal when studying the precipitation anomaly of the YHB.
Interannual and interdecadal variations of South Asia high (SAH) and the relation with the summer precipitation of China are studied by use of the NCEP/NCAR monthly mean reanalysis data and observational data at stations given by National Meteorological Center. It is found that all of the parameters of SAH except the ridge line position exist the remarkably interdecadal variations in summer. There is no significant partial correlation between the intensity and the east ridge point (ERP) of SAH when the area is stable. The simultaneous correlation shows that the significant positive correlation occurs between the location of the ERP of SAH and the summer rainfall of the YangtzeHuaihe River Basin (YHB) during 1979-2008, and this correlation has a big change through the sliding correlation analysis, turning from the negative correlation before the 1970s to the positive one. All these exhibit that the position of the ERP of SAH can be considered as a strong signal when studying the precipitation anomaly of the YHB.
2010, 36(4):57-62.
DOI: 10.7519/j.issn.1000-0526.2010.4.010
Abstract:
Based on the tropopause observation data of eight sounding stations from 1980 to 2004 over Gansu Province, the seasonal variations of the first and the second tropopause heights were analyzed. The results indicated that there are significant seasonal differences in the two kinds of tropopause over Gansu Province. The second (first) tropopause is the main type in summer (winter). The annual average height of the first tropopause is higher in spring and autumn than in winter and summer, the average height of the second tropopause is lower in autumn and winter than in spring and winter. There is an obvious annual variation in the tropopause height in this location, the first tropopause height in each season has a periodic oscillation of 5 to 6 years, the second tropopause heigh has a quasioscillation of 3 years. The two kinds of tropopause heights in each season have a mainly rising trend in Gansu Province in the recent 25 years, especially in summer.
Based on the tropopause observation data of eight sounding stations from 1980 to 2004 over Gansu Province, the seasonal variations of the first and the second tropopause heights were analyzed. The results indicated that there are significant seasonal differences in the two kinds of tropopause over Gansu Province. The second (first) tropopause is the main type in summer (winter). The annual average height of the first tropopause is higher in spring and autumn than in winter and summer, the average height of the second tropopause is lower in autumn and winter than in spring and winter. There is an obvious annual variation in the tropopause height in this location, the first tropopause height in each season has a periodic oscillation of 5 to 6 years, the second tropopause heigh has a quasioscillation of 3 years. The two kinds of tropopause heights in each season have a mainly rising trend in Gansu Province in the recent 25 years, especially in summer.
11 The Study on Wind Speed Change with Height Under
Different Terrain Conditions in Hubei Province
2010, 36(4):63-67.
DOI: 10.7519/j.issn.1000-0526.2010.4.011
Abstract:
The vertical wind shear characteristics under the different terrain conditions are explored by using the observed data of whole year in Longganhu of Huanggang, Xianjuding of Dawu and Huashanguan of Zhongxiang, and the change characteristics such as daily and seasonal variations are analyzed with methods of linear analysis and leastsquares fitting. The results showed that， the variability of wind speed in Huashanguan is the biggest as the sea level increases, and followed by Longganhu, and the smallest is Xianjuding. Moreover, the trends in wind shear index are different with increasing heights, the curve of daily change is near the sinusoidal waveform; the seasonal variations in different terrain conditions are shown obviously. Compared with the normal circumstances, the vertical wind shear index is significantly reduced in windy conditions. Finally, a conclusion may be drawn that there is a significant impact of terrain and the underlying surface on the vertical change of wind.
The vertical wind shear characteristics under the different terrain conditions are explored by using the observed data of whole year in Longganhu of Huanggang, Xianjuding of Dawu and Huashanguan of Zhongxiang, and the change characteristics such as daily and seasonal variations are analyzed with methods of linear analysis and leastsquares fitting. The results showed that， the variability of wind speed in Huashanguan is the biggest as the sea level increases, and followed by Longganhu, and the smallest is Xianjuding. Moreover, the trends in wind shear index are different with increasing heights, the curve of daily change is near the sinusoidal waveform; the seasonal variations in different terrain conditions are shown obviously. Compared with the normal circumstances, the vertical wind shear index is significantly reduced in windy conditions. Finally, a conclusion may be drawn that there is a significant impact of terrain and the underlying surface on the vertical change of wind.
2010, 36(4):68-74.
DOI: 10.7519/j.issn.1000-0526.2010.4.012
Abstract:
One severe mesoscale convective system with damaging straightline wind occurred on 21 June 2005 in northern Shandong Province. Based on the analysis of lightning activities, radar echoes and cloud images, it was found that the cloudtoground (CG) flash rates increased rapidly at the initial developing stage, and they were very high (about above 20 fl per 5 minutes) all along the mature stage. At the dissipating stage, positive CG flashes gradually dominated. Almost all negative CG flashes occurred in the convective precipitation regions, whereas most positive CG flashes corresponded to stratiform precipitiation regions. The hourly flash rate lagged behind the minimum brightness temperature, and the area of cold cloud shield with temperature colder than -50 ℃ lagged behind the hourly flash rate. Strong wind at the surface occurred in or near the regions with dense CG flashes.The pulse of CG flash rate was slightly ahead of the occurrence of severe surface wind. The damaging straightline wind was due to downbursts. The maximum wind speed observed at weather station was approximate to the maximum potential speed calculated by WINDEX.
One severe mesoscale convective system with damaging straightline wind occurred on 21 June 2005 in northern Shandong Province. Based on the analysis of lightning activities, radar echoes and cloud images, it was found that the cloudtoground (CG) flash rates increased rapidly at the initial developing stage, and they were very high (about above 20 fl per 5 minutes) all along the mature stage. At the dissipating stage, positive CG flashes gradually dominated. Almost all negative CG flashes occurred in the convective precipitation regions, whereas most positive CG flashes corresponded to stratiform precipitiation regions. The hourly flash rate lagged behind the minimum brightness temperature, and the area of cold cloud shield with temperature colder than -50 ℃ lagged behind the hourly flash rate. Strong wind at the surface occurred in or near the regions with dense CG flashes.The pulse of CG flash rate was slightly ahead of the occurrence of severe surface wind. The damaging straightline wind was due to downbursts. The maximum wind speed observed at weather station was approximate to the maximum potential speed calculated by WINDEX.
2010, 36(4):75-79.
DOI: 10.7519/j.issn.1000-0526.2010.4.013
Abstract:
A new approach was developed to retrieve air temperature from remotely sensed data. In a sparse vegetation region, based on the relation between air temperature (Ta) and land surface temperature (TLS), three linear regression equations have been established according to the different grade of elevation. In a dense vegetation region, “Vi-Ts” (vegetation indexsurface temperature) method is used for the estimation of air temperature. Air temperature from this prototype algorithm is validated using NOAAAVHRR data with actual observations of air temperature at China meteorological stations. The error in the sparse vegetation is about 1.5-1.8 ℃(R2=0.89) and the error in the dense vegetation is averagely 1.61 ℃(R2=0.90). The results show that algorithm for estimating air temperature has a high accuracy and can be used in operation.
A new approach was developed to retrieve air temperature from remotely sensed data. In a sparse vegetation region, based on the relation between air temperature (Ta) and land surface temperature (TLS), three linear regression equations have been established according to the different grade of elevation. In a dense vegetation region, “Vi-Ts” (vegetation indexsurface temperature) method is used for the estimation of air temperature. Air temperature from this prototype algorithm is validated using NOAAAVHRR data with actual observations of air temperature at China meteorological stations. The error in the sparse vegetation is about 1.5-1.8 ℃(R2=0.89) and the error in the dense vegetation is averagely 1.61 ℃(R2=0.90). The results show that algorithm for estimating air temperature has a high accuracy and can be used in operation.
2010, 36(4):80-84.
DOI: 10.7519/j.issn.1000-0526.2010.4.014
Abstract:
The implementation of functional modules is described in the Inner Mongolia Meteorological Bureau integrated information system. It realizes the unified platform through the prevailing system development and mature technology, and fully uses the technological transfer method including related data formats, such as the lotus database format, word and other text formats, graphics and video formats as well as other custom applications, and then carried out a reasonable format conversion and display based on the existing network environment and existing business application systems, thus basically solves many problems in the management and assessment aspects.
The implementation of functional modules is described in the Inner Mongolia Meteorological Bureau integrated information system. It realizes the unified platform through the prevailing system development and mature technology, and fully uses the technological transfer method including related data formats, such as the lotus database format, word and other text formats, graphics and video formats as well as other custom applications, and then carried out a reasonable format conversion and display based on the existing network environment and existing business application systems, thus basically solves many problems in the management and assessment aspects.
2010, 36(4):85-89.
DOI: 10.7519/j.issn.1000-0526.2010.4.015
Abstract:
At the beginning of 2008, persistent largescale of ice and snow weather hit Zhejiang Province. With the support of remote sensing and geographical information system (GIS) technology, a deep study on the genesis, developing and melting of snow was carried out. First, snow and cloud were distinguished well using MODIS data, and a snow model (normalized difference snow index) was established to extract the snow information. Then, spatial and quantitative analyses on the distribution of snow cover were conducted, and the melt character was studied through the snow cover depletion curve. Finally, a preliminary assessment of the disaster of forests was discussed using the method of ΔNDVI. The results show that snow melt has a decreasing trend of minus exponent. Originally, the snow cover ratio at the middle altitude (300-900 m) could reach over 70% and was more than that at altitudes higher than 900 m or lower than 300 m. Meanwhile, the disparities in the different elevation zones became narrower along with the snow melting. The speed of snow melt slowed down significantly as before. On Feb.16, snow cover was consistent with the terrain character, that is, the higher the elevation is, the greater the snow cover is. When most snow is distributed in the high mountainous area, the speed of snow melt is much slower as before. Until Feb. 29, there was no snow at the study area. The degree of disaster is related to the time of snow cover and the elevation of the forest area. Working at realtime monitoring, dynamic analysis and disaster assessment of snow cover in South China is very important to the disaster prevention and reduction of local government.
At the beginning of 2008, persistent largescale of ice and snow weather hit Zhejiang Province. With the support of remote sensing and geographical information system (GIS) technology, a deep study on the genesis, developing and melting of snow was carried out. First, snow and cloud were distinguished well using MODIS data, and a snow model (normalized difference snow index) was established to extract the snow information. Then, spatial and quantitative analyses on the distribution of snow cover were conducted, and the melt character was studied through the snow cover depletion curve. Finally, a preliminary assessment of the disaster of forests was discussed using the method of ΔNDVI. The results show that snow melt has a decreasing trend of minus exponent. Originally, the snow cover ratio at the middle altitude (300-900 m) could reach over 70% and was more than that at altitudes higher than 900 m or lower than 300 m. Meanwhile, the disparities in the different elevation zones became narrower along with the snow melting. The speed of snow melt slowed down significantly as before. On Feb.16, snow cover was consistent with the terrain character, that is, the higher the elevation is, the greater the snow cover is. When most snow is distributed in the high mountainous area, the speed of snow melt is much slower as before. Until Feb. 29, there was no snow at the study area. The degree of disaster is related to the time of snow cover and the elevation of the forest area. Working at realtime monitoring, dynamic analysis and disaster assessment of snow cover in South China is very important to the disaster prevention and reduction of local government.
2010, 36(4):90-95.
DOI: 10.7519/j.issn.1000-0526.2010.4.016
Abstract:
A radar quantitative precipitation estimation group system is described in this paper which is established based on rain gauge adjustment techniques and is aimed to apply to meteorological operations. It provides hourly precipitation field in 10 minute interval and 1 km×1 km spacial resolution. Evaluation results by use of the data in the past three years show that the more the adjustment rain gauges, the higher the estimated precipitation accuracy. The relative error of hourly estimation during the year 2003 is about 40%, and even lower than 20% for the total precipitation in a precipitation event. The longer and larger the rain event lasts and covers, the higher the accuracy as well if the density of rain gauge station keeps fixed.
A radar quantitative precipitation estimation group system is described in this paper which is established based on rain gauge adjustment techniques and is aimed to apply to meteorological operations. It provides hourly precipitation field in 10 minute interval and 1 km×1 km spacial resolution. Evaluation results by use of the data in the past three years show that the more the adjustment rain gauges, the higher the estimated precipitation accuracy. The relative error of hourly estimation during the year 2003 is about 40%, and even lower than 20% for the total precipitation in a precipitation event. The longer and larger the rain event lasts and covers, the higher the accuracy as well if the density of rain gauge station keeps fixed.
2010, 36(4):96-100.
DOI: 10.7519/j.issn.1000-0526.2010.4.017
Abstract:
A method of selecting contrast cloud automatically and analyzing the seeding effect according to radar echo parameters is brought forward, aiming at physical test of convective cloud precipitation enhancement. Based on the Doppler radar data products, the contrast cloud is selected automatically in all convective cells at the very time when seeding by comparing their beginning time, position and orientation with those of seeded cloud, and calculating the analog deviation of varying characteristics of echo parameters before seeding. Then, it is presented the variation of echo parameters of seeded cloud and comparison between echo parameters of seeded cloud and that of contrast cloud. In view of this method, a set of seeding effect analysis software of convective cloud rainfall enhancement with radar products has been designed and developed. The software has been used in the precipitation enhancement operation experiments in Hubei Province. The results show that this method can identify the contrast cloud in realtime, eliminate errors caused by manmade judging to some extent, and make the effect analysis on convective cloud rainfall enhancement more scientifically.
A method of selecting contrast cloud automatically and analyzing the seeding effect according to radar echo parameters is brought forward, aiming at physical test of convective cloud precipitation enhancement. Based on the Doppler radar data products, the contrast cloud is selected automatically in all convective cells at the very time when seeding by comparing their beginning time, position and orientation with those of seeded cloud, and calculating the analog deviation of varying characteristics of echo parameters before seeding. Then, it is presented the variation of echo parameters of seeded cloud and comparison between echo parameters of seeded cloud and that of contrast cloud. In view of this method, a set of seeding effect analysis software of convective cloud rainfall enhancement with radar products has been designed and developed. The software has been used in the precipitation enhancement operation experiments in Hubei Province. The results show that this method can identify the contrast cloud in realtime, eliminate errors caused by manmade judging to some extent, and make the effect analysis on convective cloud rainfall enhancement more scientifically.
2010, 36(4):101-105.
DOI: 10.7519/j.issn.1000-0526.2010.4.018
Abstract:
Overall in 2009, the weather and climate are characterized by high temperatures and less precipitation. In this year, summer precipitation is the least in the past 10 years, regional and persistent drought was very significant, there is a serious drought in Huanghuai region and North China in winter. In summer and autumn, severe drought is monitored in the southwest of Northeast China, western Jiangnan, obviously drought in western South China and southern Southwest China. The typhoon number is significantly less than the normal generated over the South China Sea and the West Pacific. However, the number of landing China is more than normal, as well as the first landing one occurs earlier than normal. It is shown that the SSTA (SST anomaly) over the central and eastern Pacific was below normal before spring of 2009, and changed into a warm phase in April 2009. An El Nino event begins in June. Due to the influence forced by SSTA and interaction between ocean and atmosphere, the general circulation over the Northern Hemisphere is shown the dominant anomalies which have been characterized as respondence as follows: the intensity and position of subtropical high over the West Pacific vary more frequently than normal; the tropical convection in the warm pool of West Pacific is more active from winter to spring and near normal from summer to fall of 2009 compared to the normal; and the transition between meridional and zonal circulations is carried out by turns. The zonal circulation prevails in May over the midhigh latitude area of Asia; the meridional circulation prevails in June, October and November. These may be the main factors that influence climate in China in 2009.
Overall in 2009, the weather and climate are characterized by high temperatures and less precipitation. In this year, summer precipitation is the least in the past 10 years, regional and persistent drought was very significant, there is a serious drought in Huanghuai region and North China in winter. In summer and autumn, severe drought is monitored in the southwest of Northeast China, western Jiangnan, obviously drought in western South China and southern Southwest China. The typhoon number is significantly less than the normal generated over the South China Sea and the West Pacific. However, the number of landing China is more than normal, as well as the first landing one occurs earlier than normal. It is shown that the SSTA (SST anomaly) over the central and eastern Pacific was below normal before spring of 2009, and changed into a warm phase in April 2009. An El Nino event begins in June. Due to the influence forced by SSTA and interaction between ocean and atmosphere, the general circulation over the Northern Hemisphere is shown the dominant anomalies which have been characterized as respondence as follows: the intensity and position of subtropical high over the West Pacific vary more frequently than normal; the tropical convection in the warm pool of West Pacific is more active from winter to spring and near normal from summer to fall of 2009 compared to the normal; and the transition between meridional and zonal circulations is carried out by turns. The zonal circulation prevails in May over the midhigh latitude area of Asia; the meridional circulation prevails in June, October and November. These may be the main factors that influence climate in China in 2009.
2010, 36(4):106-110.
DOI: 10.7519/j.issn.1000-0526.2010.4.019
Abstract:
The year 2009 was the fifth warmest year on record. In early 2009, snow storms, extreme low temperature and cold waves blanketed most Europe; and consecutive snow storms hit North America. Severe drought persisted in northern China from boreal autumn to winter. Hot wave raided southeast Australia. During summer, eastern China, South Asia, most Europe and western America seaboard suffered hot wave. During 2009, severe drought conditions maintained in Australia, Mexico and eastern Africa. The El Nino event came forth in June. During the year, tropical cyclone activities were weaker than normal in the western North Pacific and in the Atlantic Ocean.
The year 2009 was the fifth warmest year on record. In early 2009, snow storms, extreme low temperature and cold waves blanketed most Europe; and consecutive snow storms hit North America. Severe drought persisted in northern China from boreal autumn to winter. Hot wave raided southeast Australia. During summer, eastern China, South Asia, most Europe and western America seaboard suffered hot wave. During 2009, severe drought conditions maintained in Australia, Mexico and eastern Africa. The El Nino event came forth in June. During the year, tropical cyclone activities were weaker than normal in the western North Pacific and in the Atlantic Ocean.
2010, 36(4):111-115.
DOI: 10.7519/j.issn.1000-0526.2010.4.020
Abstract:
In this paper, two drought monitoring methods of temperature vegetation dryness index (TVDI) and vegetation supply water index (VSWI) based on temperature／vegetation supply water index (NDVI) were contrasted and analyzed by MODIS data in semihumid and transitional zones in Anhui Province. The grades of TDVI and VSWI about drought monitoring combining accumulated humidity index were established, which were validated by local soil moisture． TVDI and VSWI and accumulated humidity index have been shown a remarkable correlation, and the TVDI drought monitoring method is more suitable than VSWI in researching area.
In this paper, two drought monitoring methods of temperature vegetation dryness index (TVDI) and vegetation supply water index (VSWI) based on temperature／vegetation supply water index (NDVI) were contrasted and analyzed by MODIS data in semihumid and transitional zones in Anhui Province. The grades of TDVI and VSWI about drought monitoring combining accumulated humidity index were established, which were validated by local soil moisture． TVDI and VSWI and accumulated humidity index have been shown a remarkable correlation, and the TVDI drought monitoring method is more suitable than VSWI in researching area.
2010, 36(4):116-119.
DOI: 10.7519/j.issn.1000-0526.2010.4.021
Abstract:
Based on the sugarcane growing distribution information by remote sensing in Guangxi and a lot of field investigations, the values of sugarcane NDVI before, during and after the period of chilling and freezing injuries in early 2008 and the same term in 2007 were compared and analyzed with the data of EOS/MODIS remote sensing, the result showed that monitoring sugarcane chilling and freezing injuries by use of remote sensing technique is of great economic significance.
Based on the sugarcane growing distribution information by remote sensing in Guangxi and a lot of field investigations, the values of sugarcane NDVI before, during and after the period of chilling and freezing injuries in early 2008 and the same term in 2007 were compared and analyzed with the data of EOS/MODIS remote sensing, the result showed that monitoring sugarcane chilling and freezing injuries by use of remote sensing technique is of great economic significance.
2010, 36(4):120-125.
DOI: 10.7519/j.issn.1000-0526.2010.4.022
Abstract:
Three groundbased microwave radiometers were introduced into the artificial rainfall project for Sanjiangyuan Nature Reserve in 2008. Network data processing system for groundbased microwave radiometers was designed for the sake of acquiring the atmospheric information rapidly, visually and accurately, which was observed in the whole reserve. According to the function, the system can be divided into four parts: data uploading program, databases designing, data writing into database program and user terminal program for display. Structured programming was used for the system development. Delphi was used as the programming language, and Microsoft SQL Server 2000 as the database was selected to realize the functions of realtime temporary database and historical database establishing, microwave radiometer data conversion to the standard format, transformation, appending, data query, data exportation, and data display. After more than six months of software testing, the system is operating well overall, and is about to apply in the meteorological observation.
Three groundbased microwave radiometers were introduced into the artificial rainfall project for Sanjiangyuan Nature Reserve in 2008. Network data processing system for groundbased microwave radiometers was designed for the sake of acquiring the atmospheric information rapidly, visually and accurately, which was observed in the whole reserve. According to the function, the system can be divided into four parts: data uploading program, databases designing, data writing into database program and user terminal program for display. Structured programming was used for the system development. Delphi was used as the programming language, and Microsoft SQL Server 2000 as the database was selected to realize the functions of realtime temporary database and historical database establishing, microwave radiometer data conversion to the standard format, transformation, appending, data query, data exportation, and data display. After more than six months of software testing, the system is operating well overall, and is about to apply in the meteorological observation.
2010, 36(4):126-131.
DOI: 10.7519/j.issn.1000-0526.2010.4.023
Abstract:
In order to reveal the characteristics of the boundary layer ozone vertical profiles in winter in Urumqi, the observation experiment with tethered balloon has been carried out from 11 to 13 January 2008. Based on the observation experiment data and some related data， the vertical distribution characters of ozone concentration and the relationship with meteorological factors were studied. The results showed that: The ozone concentration is lower below 500-800 m during the daytime and the distribution area of high concentration ozone appears over this height. However, the ozone concentration is lower in the range of whole observed height at night. There existed a close relationship between the ozone concentration and the meteorological factors including solar radiation， temperature stratification， wind and relative humidity.The distribution area of high concentration ozone exsits over the inversion base， and there is a significant inverse correlation between the ozone concentration and the relative humidity. The nitrogen oxides in the near surface has an important influence on ozone concentration. The above facts obtained indicate that the ozone in the lower troposphere has significant temporal and spatial variations in winter in Urumqi， which results from the joint effects of various factors.
In order to reveal the characteristics of the boundary layer ozone vertical profiles in winter in Urumqi, the observation experiment with tethered balloon has been carried out from 11 to 13 January 2008. Based on the observation experiment data and some related data， the vertical distribution characters of ozone concentration and the relationship with meteorological factors were studied. The results showed that: The ozone concentration is lower below 500-800 m during the daytime and the distribution area of high concentration ozone appears over this height. However, the ozone concentration is lower in the range of whole observed height at night. There existed a close relationship between the ozone concentration and the meteorological factors including solar radiation， temperature stratification， wind and relative humidity.The distribution area of high concentration ozone exsits over the inversion base， and there is a significant inverse correlation between the ozone concentration and the relative humidity. The nitrogen oxides in the near surface has an important influence on ozone concentration. The above facts obtained indicate that the ozone in the lower troposphere has significant temporal and spatial variations in winter in Urumqi， which results from the joint effects of various factors.
MA Zhongyuan
,
ZHU Chunqiao
,
WANG Huajun
,
YU Bing
,
PAN Jiangping
,
LIN Chun
,
XIAO Yuling
,
GUI Baoyu
2010, 36(4):132-136.
DOI: 10.7519/j.issn.1000-0526.2010.4.024
Abstract:
With the development of the meteorological cause and the requirement of fine weather forecast, the requirement and concept of time are been recognized more and more important for meteorological operational system. The unified time of meteorological operational system plays an important role in improving the quality of observation data. GPSNET time service system uses the GPS time source and system received software technology to make time service for computer. Standard time can be transmitted to certain users by net with Network time service publishing and Network user terminal received software. At the same time, the security of the GPS system and Network is considered fully. The results show that: GPSNET time service system can obtain GPS time source information accurately and release to user terminals through network technology to make meteorological oper〖HJ〗ational system obtain the standard time (error <1 s). The way of network publishing and meteorological internal network limitation can reduce the server and user terminal’s burden effectively and preventing external net virus’s invasion. The quick, exact and synchronization solution of time service is provided for meteorological equipment and meteorological operation by GPSNet time service system.
With the development of the meteorological cause and the requirement of fine weather forecast, the requirement and concept of time are been recognized more and more important for meteorological operational system. The unified time of meteorological operational system plays an important role in improving the quality of observation data. GPSNET time service system uses the GPS time source and system received software technology to make time service for computer. Standard time can be transmitted to certain users by net with Network time service publishing and Network user terminal received software. At the same time, the security of the GPS system and Network is considered fully. The results show that: GPSNET time service system can obtain GPS time source information accurately and release to user terminals through network technology to make meteorological oper〖HJ〗ational system obtain the standard time (error <1 s). The way of network publishing and meteorological internal network limitation can reduce the server and user terminal’s burden effectively and preventing external net virus’s invasion. The quick, exact and synchronization solution of time service is provided for meteorological equipment and meteorological operation by GPSNet time service system.
2010, 36(4):137-141.
DOI: 10.7519/j.issn.1000-0526.2010.4.025
Abstract:
The country has 2.4 mm precipitation more than the same period of normal years during January 2010 and the average temperature is 1.4 ℃ higher than that of same period. The cold air is active in this month, but only two of them reach the strong intensity and thus parts of northern Xinjiang suffer from snowstorm . The times of main precipitation process in whole country are up to six in all in this month. Additionally, the polar vortex and subtropical high are stronger than the same period of normal years, but the south branch trough is weaker than the same period of normal years.
The country has 2.4 mm precipitation more than the same period of normal years during January 2010 and the average temperature is 1.4 ℃ higher than that of same period. The cold air is active in this month, but only two of them reach the strong intensity and thus parts of northern Xinjiang suffer from snowstorm . The times of main precipitation process in whole country are up to six in all in this month. Additionally, the polar vortex and subtropical high are stronger than the same period of normal years, but the south branch trough is weaker than the same period of normal years.
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ISSN:1000-0526 CN:11-2282/P