ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 33,Issue 6,2007 Table of Contents
2007, 33(6):3-10.
DOI: 10.7519/j.issn.1000-0526.2007.06.001
Abstract:
The main sources of remote sensing data and data processing methods of snow information retrieval are introduced. For the optical remote sensing, the AVHRR and MODIS data were widely used to distinguish the snow cover from other l and cover types mostly according to the high reflectance of snow in the visible band and low in the near infrared band; and the snow cover area and depth also c an be obtained by regression equations. With advanced sensors, the data from MOD IS is obviously superior to that from AVHRR in algorithms and resolution to deri ve the snow information. For the microwave remote sensing: passive microwave rem ote sensing has allweather and daynight data acquisition capability, the ear th surface information can be obtained in whole day. So it is more useful to detec t the snow depth than optical remote sensing. The snow cover was detected throug h retrieving the brightness temperature of snow. Active microwave remote sensing can estimate snow cover by different backscattering coefficient. Finally, the m ain problem and development trends of snow information retrieval technique by us ing satellite remote sensing data are discussed.
The main sources of remote sensing data and data processing methods of snow information retrieval are introduced. For the optical remote sensing, the AVHRR and MODIS data were widely used to distinguish the snow cover from other l and cover types mostly according to the high reflectance of snow in the visible band and low in the near infrared band; and the snow cover area and depth also c an be obtained by regression equations. With advanced sensors, the data from MOD IS is obviously superior to that from AVHRR in algorithms and resolution to deri ve the snow information. For the microwave remote sensing: passive microwave rem ote sensing has allweather and daynight data acquisition capability, the ear th surface information can be obtained in whole day. So it is more useful to detec t the snow depth than optical remote sensing. The snow cover was detected throug h retrieving the brightness temperature of snow. Active microwave remote sensing can estimate snow cover by different backscattering coefficient. Finally, the m ain problem and development trends of snow information retrieval technique by us ing satellite remote sensing data are discussed.
2007, 33(6):11-18.
DOI: 10.7519/j.issn.1000-0526.2007.06.002
Abstract:
The vertical integrated atmospheric moisture, or the precipitable water vapor (PWV) with high temporal and spatial resolution retrieved from a ground based GPS network can supply the gap of the conventional radiosoundings. In order to evaluate the improvement of the GPS/PWV data assimilating to operat ional numerical forecasts, a continuous experiment of 3dimentional variation a ssimilation (3DVar) of GPS/PWV data into MM5 model is conducted. Through the 3DVar assimilation of GPS/PWV data, the initial field of MM5 model is built at 20:00 every day, and the hourly rainfalls over the Yangtze River Delta area a re forecasted for 24 hours. Comparing with the forecasted 6 hour's accumulative rainfalls without GPS/PWV data assimilation，the improvement effects of the MM5 precipitation forecasts with GPS/PWV data assimilation are evaluated by several test methods. The results show that the MM5 precipitation forecasts with GPS/PWV data assimilation are totally improved in the most days and most stations, espe cially in the days with smaller area of precipitation. The improvement of precip itation forecast mainly attributes to the significant decrease of the percent of false detection. The areas where the precipitation forecasts are improved signi ficantly coincide in the area with sparser regular radiosounding data.
The vertical integrated atmospheric moisture, or the precipitable water vapor (PWV) with high temporal and spatial resolution retrieved from a ground based GPS network can supply the gap of the conventional radiosoundings. In order to evaluate the improvement of the GPS/PWV data assimilating to operat ional numerical forecasts, a continuous experiment of 3dimentional variation a ssimilation (3DVar) of GPS/PWV data into MM5 model is conducted. Through the 3DVar assimilation of GPS/PWV data, the initial field of MM5 model is built at 20:00 every day, and the hourly rainfalls over the Yangtze River Delta area a re forecasted for 24 hours. Comparing with the forecasted 6 hour's accumulative rainfalls without GPS/PWV data assimilation，the improvement effects of the MM5 precipitation forecasts with GPS/PWV data assimilation are evaluated by several test methods. The results show that the MM5 precipitation forecasts with GPS/PWV data assimilation are totally improved in the most days and most stations, espe cially in the days with smaller area of precipitation. The improvement of precip itation forecast mainly attributes to the significant decrease of the percent of false detection. The areas where the precipitation forecasts are improved signi ficantly coincide in the area with sparser regular radiosounding data.
2007, 33(6):19-24.
DOI: 10.7519/j.issn.1000-0526.2007.06.003
Abstract:
The spacetime distribution features of the atmospheric precipitable wa ter vapor over the Hebei province are preliminarily analyzed using the GPS data of Shijiazhuang, Zhangjiakou and Qinhuangdao from Apr. to Nov. 2005, which were processed b y GAMIT software .It indicates that the precipitable water changes remarkably with seasons and precipitation mostly occurs in the period when precipitable w ater is larger than its threshold value. It also suggested that different variat ion characteristics are correspondent to the different weather systems.
The spacetime distribution features of the atmospheric precipitable wa ter vapor over the Hebei province are preliminarily analyzed using the GPS data of Shijiazhuang, Zhangjiakou and Qinhuangdao from Apr. to Nov. 2005, which were processed b y GAMIT software .It indicates that the precipitable water changes remarkably with seasons and precipitation mostly occurs in the period when precipitable w ater is larger than its threshold value. It also suggested that different variat ion characteristics are correspondent to the different weather systems.
2007, 33(6):25-31.
DOI: 10.7519/j.issn.1000-0526.2007.06.004
Abstract:
Based on the data of 20 meteorological stations and two automatic stat ions and the data of 325m meteorological tower of IAP, characteristics of Beijin g urban heat islands (UHI) in July,2003 are analyzed. The results show that str ong urban heat islands occur in the night in July overBeijing under some specif ic weather conditions. The days with strong urban heat islands occupy about 1/3 of the total days. In addition, the characteristics and influencing factors of a strong urban heat island are analyzed in details. Results show that the UHI c enter lies over the urban area surrounding Tiananmen, Baijiazhuang, and the stro ng UHI occurs in the clear sky night with strong sunlight in the daytime. The weak wind and the temperature inversion are very important to the formation and maint enance of a strong UHI. But in the next daytime, the temperature inversion disap peared, and the amount of sunlight in northern suburb is more than that in the u rban area, which makes the surface temperature of suburban atmosphere rise faste r and higher than that of the urban surface atmosphere, and the intensity of UHI weaker. In addition, the strong urban heat island was simulated with MM5. And t he results show that when only the physical properties such as the roughness of the underlying surface were considered in MM5, simulated the urban surface tempe rature and the intensity of UHI don't accord with the observational data. Howeve r when the anthropogenic heat and urban heat storage are taken into account, the numeric simulation of UHI could be improved effectively. The anthropogenic heat and urban heat storage play very important role in the formation of the strong UHI in the night.
Based on the data of 20 meteorological stations and two automatic stat ions and the data of 325m meteorological tower of IAP, characteristics of Beijin g urban heat islands (UHI) in July,2003 are analyzed. The results show that str ong urban heat islands occur in the night in July overBeijing under some specif ic weather conditions. The days with strong urban heat islands occupy about 1/3 of the total days. In addition, the characteristics and influencing factors of a strong urban heat island are analyzed in details. Results show that the UHI c enter lies over the urban area surrounding Tiananmen, Baijiazhuang, and the stro ng UHI occurs in the clear sky night with strong sunlight in the daytime. The weak wind and the temperature inversion are very important to the formation and maint enance of a strong UHI. But in the next daytime, the temperature inversion disap peared, and the amount of sunlight in northern suburb is more than that in the u rban area, which makes the surface temperature of suburban atmosphere rise faste r and higher than that of the urban surface atmosphere, and the intensity of UHI weaker. In addition, the strong urban heat island was simulated with MM5. And t he results show that when only the physical properties such as the roughness of the underlying surface were considered in MM5, simulated the urban surface tempe rature and the intensity of UHI don't accord with the observational data. Howeve r when the anthropogenic heat and urban heat storage are taken into account, the numeric simulation of UHI could be improved effectively. The anthropogenic heat and urban heat storage play very important role in the formation of the strong UHI in the night.
2007, 33(6):32-36.
DOI: 10.7519/j.issn.1000-0526.2007.06.005
Abstract:
A heavy pollution occurred in Beijing during 7th-10th April 2006. The synoptic situation, meteorological element, flow field and atmospheric stability of the event are analyzed. The results show that the same sand dust affected Be ijing twice and caused continues heavy weather pollution. For the first time, th e sand dust of inner Mongolia came down along with the north-west flow and reach ed Beijing. For the second time, based on “refluence" weather background, along w ith the easterly wind, the sand dust which had moved to downstream returned Beiji ng. The heavy weather pollution is a common action result of sand dust and ca lming weather condition.
A heavy pollution occurred in Beijing during 7th-10th April 2006. The synoptic situation, meteorological element, flow field and atmospheric stability of the event are analyzed. The results show that the same sand dust affected Be ijing twice and caused continues heavy weather pollution. For the first time, th e sand dust of inner Mongolia came down along with the north-west flow and reach ed Beijing. For the second time, based on “refluence" weather background, along w ith the easterly wind, the sand dust which had moved to downstream returned Beiji ng. The heavy weather pollution is a common action result of sand dust and ca lming weather condition.
2007, 33(6):37-43.
DOI: 10.7519/j.issn.1000-0526.2007.06.006
Abstract:
Based on the observation data of New Generation Weather Radar (CINRAD) and hourly surface rain gauge data, a subsection optimized ZI relationshi p was obtained, the rainfall measurements were conducted in Xiang hongdian and Fozil ing subcatchments which located in the upper reaches of Pihe. The results show t hat by this optimized relationship, the ratio between the basin accumulated area rainfall and rain gauge value improved from 39% to 73% while the correlatio n coefficient from 0.78 to 0.8. On the 528-hour time sequence of Foziling subcatch ment with the optimized ZI relationship, the trend line slope of mean area rainfall increased from 0.40 to 0.72 compared to rainfall from rain gauge, while the ratio between the accumulated area rainfall value above 1mm/h and the accumulated rain gauge value improved from 48.4% to 85.9%. Obviously, optimized ZI radar rainfall value is closer to the observed rainfall value, and the precision of area rainfall by radar is strictly improved.
Based on the observation data of New Generation Weather Radar (CINRAD) and hourly surface rain gauge data, a subsection optimized ZI relationshi p was obtained, the rainfall measurements were conducted in Xiang hongdian and Fozil ing subcatchments which located in the upper reaches of Pihe. The results show t hat by this optimized relationship, the ratio between the basin accumulated area rainfall and rain gauge value improved from 39% to 73% while the correlatio n coefficient from 0.78 to 0.8. On the 528-hour time sequence of Foziling subcatch ment with the optimized ZI relationship, the trend line slope of mean area rainfall increased from 0.40 to 0.72 compared to rainfall from rain gauge, while the ratio between the accumulated area rainfall value above 1mm/h and the accumulated rain gauge value improved from 48.4% to 85.9%. Obviously, optimized ZI radar rainfall value is closer to the observed rainfall value, and the precision of area rainfall by radar is strictly improved.
7 Analysis of a Torrential Rain over Liaodong Peninsula Based on
Radar Data and Simulation Output
2007, 33(6):44-50.
DOI: 10.7519/j.issn.1000-0526.2007.06.007
Abstract:
Based on the routine meteorological observations, Doppler radar data a nd the numerical simulation outputs, a mesoscale analysis of a torrential rain e vent over Liaodong Peninsula on 3 August 2004 is made. And a diagnosis of the ev ent is made by using the theory of moist potential vorticity. The results show t hat the mesoscale systems causing the torrential rain are a low level jet (LLJ), a shear line and a mesoscale depression. The meso-γ scale echoes, bandi nband echo, mesoscale cyclone, LLJ and bow echo detected by Doppler radar cause stron g convective rainfall. The analysis of simulation outputs indicates that LLJ and the two different upper level jetLLJ couplings made an important contribution to the torrential rain by producing strong ascending motion. The horizontal mois t isentropes turning to very stiff and dense state led to the development of moist slantwise vorticity and the amplification of the precipitation. The strong co nvective instability and the baroclinic instability in the low level provided th e conditions of the torrential rain.
Based on the routine meteorological observations, Doppler radar data a nd the numerical simulation outputs, a mesoscale analysis of a torrential rain e vent over Liaodong Peninsula on 3 August 2004 is made. And a diagnosis of the ev ent is made by using the theory of moist potential vorticity. The results show t hat the mesoscale systems causing the torrential rain are a low level jet (LLJ), a shear line and a mesoscale depression. The meso-γ scale echoes, bandi nband echo, mesoscale cyclone, LLJ and bow echo detected by Doppler radar cause stron g convective rainfall. The analysis of simulation outputs indicates that LLJ and the two different upper level jetLLJ couplings made an important contribution to the torrential rain by producing strong ascending motion. The horizontal mois t isentropes turning to very stiff and dense state led to the development of moist slantwise vorticity and the amplification of the precipitation. The strong co nvective instability and the baroclinic instability in the low level provided th e conditions of the torrential rain.
2007, 33(6):51-58.
DOI: 10.7519/j.issn.1000-0526.2007.06.008
Abstract:
Based on the Monitored data of the GPS network in Beijing, the relationship betw een the variation characteristics of precipitable water vapor （PWV）in the rainstorm event during 2004 flood season and its rainfall and intensity was analyzed . The results show that the increase of PWV was often restricted by the local weather system, when weather s ystem in ground and upper air picture make for the transportation of warm and moisture a ir, isohume denseness section was formed nearby Beijing, the PWV was increas ing during 1314 hours before rainstorm appearance; when there was convergence system moving eastward or mesoscale weather system forming, PWV increased s ignificantly during 34 hours before rainstorm, heavy rain appeared after value of PWV above threshold, but the value of PWV and increment did not corr espond to the rainfall.
Based on the Monitored data of the GPS network in Beijing, the relationship betw een the variation characteristics of precipitable water vapor （PWV）in the rainstorm event during 2004 flood season and its rainfall and intensity was analyzed . The results show that the increase of PWV was often restricted by the local weather system, when weather s ystem in ground and upper air picture make for the transportation of warm and moisture a ir, isohume denseness section was formed nearby Beijing, the PWV was increas ing during 1314 hours before rainstorm appearance; when there was convergence system moving eastward or mesoscale weather system forming, PWV increased s ignificantly during 34 hours before rainstorm, heavy rain appeared after value of PWV above threshold, but the value of PWV and increment did not corr espond to the rainfall.
2007, 33(6):59-66.
DOI: 10.7519/j.issn.1000-0526.2007.06.009
Abstract:
With the observation data, FY-2 cloud images data and the NCEP reanal yzed data, the development characteristics of an explosive cyclone which occurre d during June 22-23, 2003 is analyzed by synoptic diagnosis and numerical simula tion with MM5. It is indicated that the explosive cyclone was caused by combinat ion of the eastward moving high level trough over the great band of Yellow River and the warm wind sheer over southern Shandong Province. The explosive cyclone over the land during summer occurs in the place where the cyclonic curve of heig ht field meets the exit port of the jet, and it develops abruptly when it pass f rom the right to the left of jet. The development of explosive cyclone needs hig h level jet, and the southwest low level jet and southeast low level jet provide it strong warm advection and vapor transport. The explosive cycloneurs in the high energy fields, following the strong development of the ascending movement with strong divergence on high level and strong convergence on low lev el. The air has strong convective instability.
With the observation data, FY-2 cloud images data and the NCEP reanal yzed data, the development characteristics of an explosive cyclone which occurre d during June 22-23, 2003 is analyzed by synoptic diagnosis and numerical simula tion with MM5. It is indicated that the explosive cyclone was caused by combinat ion of the eastward moving high level trough over the great band of Yellow River and the warm wind sheer over southern Shandong Province. The explosive cyclone over the land during summer occurs in the place where the cyclonic curve of heig ht field meets the exit port of the jet, and it develops abruptly when it pass f rom the right to the left of jet. The development of explosive cyclone needs hig h level jet, and the southwest low level jet and southeast low level jet provide it strong warm advection and vapor transport. The explosive cycloneurs in the high energy fields, following the strong development of the ascending movement with strong divergence on high level and strong convergence on low lev el. The air has strong convective instability.
2007, 33(6):67-74.
DOI: 10.7519/j.issn.1000-0526.2007.06.010
Abstract:
The weather process of the snowstorm happened in Hami Xinjiang during 1 8—20 November 2005 and the snow was heavier in the south than that in the north. Based o n NCEP 1°×1° 6h interval reanalyzed data and the nonconventional data, dyna mic and thermodynamic diagnoses of the snowstorm caused by the vortex are discuss ed. And the methods of the Q vector and the helicity are also used to the fu rther analysis. The results are as follows: (1) With the development and eastward mo vement of the ridge in the west of Xinjiang, the vortex in Sayangling moved into Hami area and caused the snowstorm. (2) This Sayanling vortex was a deep er and cyclonic system with upward motion. There was a convergence in the low leve ls and a divergence in the high levels. (3) The obvious temperature advection an d temperature gradient can be revealed, so the baroclinicity was favorable to th e intensification and development of the vortex. (4) The convergence area of the Q vector and the positive helicity area were consistent with the vortex, wh ich can be used as an indicator in forecasting the snow in Hami.
The weather process of the snowstorm happened in Hami Xinjiang during 1 8—20 November 2005 and the snow was heavier in the south than that in the north. Based o n NCEP 1°×1° 6h interval reanalyzed data and the nonconventional data, dyna mic and thermodynamic diagnoses of the snowstorm caused by the vortex are discuss ed. And the methods of the Q vector and the helicity are also used to the fu rther analysis. The results are as follows: (1) With the development and eastward mo vement of the ridge in the west of Xinjiang, the vortex in Sayangling moved into Hami area and caused the snowstorm. (2) This Sayanling vortex was a deep er and cyclonic system with upward motion. There was a convergence in the low leve ls and a divergence in the high levels. (3) The obvious temperature advection an d temperature gradient can be revealed, so the baroclinicity was favorable to th e intensification and development of the vortex. (4) The convergence area of the Q vector and the positive helicity area were consistent with the vortex, wh ich can be used as an indicator in forecasting the snow in Hami.
2007, 33(6):75-81.
DOI: 10.7519/j.issn.1000-0526.2007.06.011
Abstract:
Qualitative and quantitative measurement for atmospheric moisture is a n effective means of improving the Inner Mongolia drought study or forecast. Ado pting NCEP and observation precipitation data from 1961-2000, the relationship b etween the moisture distribution or transportation in East Asia and summer droug ht in Inner Mongolia is analyzed. The results show that Less moisture content at low level is an important factor of Inner Mongolia drought. On the other han d, because of Qingzang plateau terrain, it is difficult that the moisture from t he Bay of Bengal and South China Sea move northward, and it could not arrive in Inner Mongolia, which is another key factor. In addition, Affected by air circul ation, the less water vapor convergence is also an important factor of Inner Mon golia drought. The moisture flux at Qingzang plateau has prominently negative co rrelation with the precipitation of whole Inner Mongolia area. Moisture passage for the precipitation of West Inner Mongolia is from the Bay of Bengal to West I nner Mongolia. The passage for the precipitation of east Inner Mongolia is from South China Sea to northeast China.
Qualitative and quantitative measurement for atmospheric moisture is a n effective means of improving the Inner Mongolia drought study or forecast. Ado pting NCEP and observation precipitation data from 1961-2000, the relationship b etween the moisture distribution or transportation in East Asia and summer droug ht in Inner Mongolia is analyzed. The results show that Less moisture content at low level is an important factor of Inner Mongolia drought. On the other han d, because of Qingzang plateau terrain, it is difficult that the moisture from t he Bay of Bengal and South China Sea move northward, and it could not arrive in Inner Mongolia, which is another key factor. In addition, Affected by air circul ation, the less water vapor convergence is also an important factor of Inner Mon golia drought. The moisture flux at Qingzang plateau has prominently negative co rrelation with the precipitation of whole Inner Mongolia area. Moisture passage for the precipitation of West Inner Mongolia is from the Bay of Bengal to West I nner Mongolia. The passage for the precipitation of east Inner Mongolia is from South China Sea to northeast China.
2007, 33(6):82-88.
DOI: 10.7519/j.issn.1000-0526.2007.06.012
Abstract:
The fog days in Henan Province from 1961 to 2005 are analyzed. The resu lts show that the yearly averaged number of fog days is more in autumn and winte r than in spring and summer, fog mainly appears in November to January of the ne xt year. The spatial distribution is very uneven and shows the trend of increase from east to west and from basin to hills. There are 5 fog centers in Henan pro vince. 40 stations are chosen for analyzing by using EOF. The results show that the first 3 modes account for 76.5% of the total accumulative variance contribution. The analyses on the correlation coefficient and the time coefficient of th e 1st mode indicate that the fog days in most areas in Henan province is increas ing, which is the same as the trend of temperature variation. Wavelet analysis i ndicates that fog days have periods of 2-4 years, 8-10 years and 19-22 years. Th e 500hPa anomaly height fields in morefog years and in lessfog years are exa mi ned. It shows the anomaly height fields of the middle and high latitude in Europ e and Asia are opposite, and display +-+ mode in more -fog years, and -+- mode i n lessfog years, respectively.
The fog days in Henan Province from 1961 to 2005 are analyzed. The resu lts show that the yearly averaged number of fog days is more in autumn and winte r than in spring and summer, fog mainly appears in November to January of the ne xt year. The spatial distribution is very uneven and shows the trend of increase from east to west and from basin to hills. There are 5 fog centers in Henan pro vince. 40 stations are chosen for analyzing by using EOF. The results show that the first 3 modes account for 76.5% of the total accumulative variance contribution. The analyses on the correlation coefficient and the time coefficient of th e 1st mode indicate that the fog days in most areas in Henan province is increas ing, which is the same as the trend of temperature variation. Wavelet analysis i ndicates that fog days have periods of 2-4 years, 8-10 years and 19-22 years. Th e 500hPa anomaly height fields in morefog years and in lessfog years are exa mi ned. It shows the anomaly height fields of the middle and high latitude in Europ e and Asia are opposite, and display +-+ mode in more -fog years, and -+- mode i n lessfog years, respectively.
2007, 33(6):89-95.
DOI: 10.7519/j.issn.1000-0526.2007.06.013
Abstract:
With correlation and resultant analysis methods，the climate aspects between the tendencies of drought and flood in Beijing and the abnormities of 500hPa circul ations are analyzed, by using the data of 500hPa height fields, subtro pical high character fields and Beijing's precipitation. The results show that t he strength and the position of the subtropical ridge are not remarkably associa ted with the summer precipitation in Beijing, while the flow pattern collocation s between the midhigh latitudes and the subtropics are. The drought summers of Beijing were associated with the teleconnection pattern over Eurasian continen t midhigh latitude (EUP pattern). In those years, anticyclone circulation preva ils in Northern China with ridge to the western side of Beijing. Beijing and near by regions are controlled by Northwest descending flow. On the other hand, a b lock high pressure in the down stream side of Beijing is the basic circulation c haracteristicsfor plentiful precipitation summers of Beijing. In those years, B eijing and near by regions are controlled by Southwest ascending flow in front o f trough. These results provide some knowledge on large scale circulation backgr ound for seasonal prediction of summer precipitation tendency in Beijing.
With correlation and resultant analysis methods，the climate aspects between the tendencies of drought and flood in Beijing and the abnormities of 500hPa circul ations are analyzed, by using the data of 500hPa height fields, subtro pical high character fields and Beijing's precipitation. The results show that t he strength and the position of the subtropical ridge are not remarkably associa ted with the summer precipitation in Beijing, while the flow pattern collocation s between the midhigh latitudes and the subtropics are. The drought summers of Beijing were associated with the teleconnection pattern over Eurasian continen t midhigh latitude (EUP pattern). In those years, anticyclone circulation preva ils in Northern China with ridge to the western side of Beijing. Beijing and near by regions are controlled by Northwest descending flow. On the other hand, a b lock high pressure in the down stream side of Beijing is the basic circulation c haracteristicsfor plentiful precipitation summers of Beijing. In those years, B eijing and near by regions are controlled by Southwest ascending flow in front o f trough. These results provide some knowledge on large scale circulation backgr ound for seasonal prediction of summer precipitation tendency in Beijing.
2007, 33(6):96-101.
DOI: 10.7519/j.issn.1000-0526.2007.06.014
Abstract:
By using the data of daily mean temperature, daily maximum and minimum tempe rature, precipitation, sunshine duration from 1961 to 2005, the inte rannual, interdecadal the seasonal climate changes are analyzed. The results a re as follows: Firstly, the annual and the seasonal temperature are rising in recent 45 years, especially, the trend of temperature increase is the most remarkable in w inter, and the recent 10 years is the warmest period. Secondly, the change of monthly mean maximum temperature is not significant, whe reas monthly mean minimum temperature is rising in the last 10 years. Thirdly, annual precipitation is in creasing and its variability is 8.19mm/10a, and so does the precipitation in wi nter and summer, but precipitation in spring and autumn are slowly decreasing. M eantime, annual precipitation in recent 10 years is also increasing, the precipi tation in winter is the largest but in autumn is the smallest. Finally, sunshine duration and mean wind speed in each period are all decreasing.
By using the data of daily mean temperature, daily maximum and minimum tempe rature, precipitation, sunshine duration from 1961 to 2005, the inte rannual, interdecadal the seasonal climate changes are analyzed. The results a re as follows: Firstly, the annual and the seasonal temperature are rising in recent 45 years, especially, the trend of temperature increase is the most remarkable in w inter, and the recent 10 years is the warmest period. Secondly, the change of monthly mean maximum temperature is not significant, whe reas monthly mean minimum temperature is rising in the last 10 years. Thirdly, annual precipitation is in creasing and its variability is 8.19mm/10a, and so does the precipitation in wi nter and summer, but precipitation in spring and autumn are slowly decreasing. M eantime, annual precipitation in recent 10 years is also increasing, the precipi tation in winter is the largest but in autumn is the smallest. Finally, sunshine duration and mean wind speed in each period are all decreasing.
2007, 33(6):102-106.
DOI: 10.7519/j.issn.1000-0526.2007.06.015
Abstract:
Qinghai Province is one of five largest pasturing areas and ranks four th in China. It is of great importance to learn the growth status of grass in t ime to ecoenvironment protection and sustainable development of stock raising. Based on the data of fresh grass weight per square meter from 22 ecoenvironmen tal monitoring stations (which were established by Qinghai Meteorological Bureau in 2002) during grass growing season from 2003 to 2004, as well as the same p eriod of MODIS data, by preprocessing，cloud detecting, EVI computing and monthl y maximum EVI compositing, MODIS EVI data were obtained corresponding to grass output data. The relationship between grassland output and EVI was established a ccording to the grass growing season and grassland type. The results show that g rassland output have a good correlation with MODIS EVI, and it can be better des cribed by the exponential function. Furthermore, the grassland output model base d on the grass growing season is better than that of based on grassland type.
Qinghai Province is one of five largest pasturing areas and ranks four th in China. It is of great importance to learn the growth status of grass in t ime to ecoenvironment protection and sustainable development of stock raising. Based on the data of fresh grass weight per square meter from 22 ecoenvironmen tal monitoring stations (which were established by Qinghai Meteorological Bureau in 2002) during grass growing season from 2003 to 2004, as well as the same p eriod of MODIS data, by preprocessing，cloud detecting, EVI computing and monthl y maximum EVI compositing, MODIS EVI data were obtained corresponding to grass output data. The relationship between grassland output and EVI was established a ccording to the grass growing season and grassland type. The results show that g rassland output have a good correlation with MODIS EVI, and it can be better des cribed by the exponential function. Furthermore, the grassland output model base d on the grass growing season is better than that of based on grassland type.
2007, 33(6):107-111.
DOI: 10.7519/j.issn.1000-0526.2007.06.016
Abstract:
The present status of early warning system of meteorological disasters of Anhui and other provinces was reviewed. The designing idea, structure and main functi ons of the system were outlined. The mancomputer interface was finished by usin g programming software of computer, which can conveniently generate the warning s ignal output with both picture and documents. The system solved the problems of urgency, consistence and integrity in the warning signal manufacture, and it al so possesses transparency and universality. Some improvements in the system des ign are discussed.
The present status of early warning system of meteorological disasters of Anhui and other provinces was reviewed. The designing idea, structure and main functi ons of the system were outlined. The mancomputer interface was finished by usin g programming software of computer, which can conveniently generate the warning s ignal output with both picture and documents. The system solved the problems of urgency, consistence and integrity in the warning signal manufacture, and it al so possesses transparency and universality. Some improvements in the system des ign are discussed.
2007, 33(6):112-117.
DOI: 10.7519/j.issn.1000-0526.2007.06.017
Abstract:
Based on artificial affecting weather works practice, the occurrence, developmen t, evolution and the route of hail in Heilongjiang Province and the radar echo f eatures are studied by using the current measurement techniques, such as new ge neration weather radar, satellite remote sensing, and the advanced communication and network technique. An artificial hailsuppression operation commend syste m was developed, which has a series of functions, such as the warning of hail we ath er, air telephone recording, commanding cannon operation scientifically, storage of operation data and microcontrol of operation. This system makes the cannon hailsuppression operation be scientific and effective.
Based on artificial affecting weather works practice, the occurrence, developmen t, evolution and the route of hail in Heilongjiang Province and the radar echo f eatures are studied by using the current measurement techniques, such as new ge neration weather radar, satellite remote sensing, and the advanced communication and network technique. An artificial hailsuppression operation commend syste m was developed, which has a series of functions, such as the warning of hail we ath er, air telephone recording, commanding cannon operation scientifically, storage of operation data and microcontrol of operation. This system makes the cannon hailsuppression operation be scientific and effective.
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