ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 46,Issue 6,2020 Table of Contents
2020, 46(6):733-744.
DOI: 10.7519/j.issn.1000-0526.2020.06.001
Abstract:
Accurate evaluation and monitoring of spectral frequency accuracy is significant for an hyper-spectral infrared (IR) interferometer before data application. A “cross-correlation method” is commonly used to evaluate the accuracy of the spectral accuracy, which allows the maximum correlation, or minimum standard deviation condition, to be met between an observed and a simulated spectrum by shifting the observed spectrum. From the perspective of the time-consuming calculation, it is not necessary to detect the frequency offset in the entire spectrum, but to evaluate the accuracy of the spectral calibration with a part of the spectral region. To comprehensively evaluate the dependence of the “cross-correlation method” on spectral regions, a preliminary selection of spectral regions was carried out based on the sensitivity analysis of the simulated spectra (with only the off-axis effect of the instrument considered), and the optimal spectral region was selected based on the sensitivity analysis of the on-orbit data. The results based on simulated spectra showed that spectral region selection is sensitive to the evaluation method in long-wave (LW) and short-wave (SW) bands, but insensitive in mid-wave (MW) band. In addition, the sensitivity is rela-ted to the envelope characteristics and to the radiation energy of the absorption line in the spectral regions. The absolute errors for selecting different spectral regions can reach 3.05 and 3.35 ppm (1 ppm=10-6) in LW and SW bands, respectively. Selecting high-radiation-energy and stable atmospheric composition regions can effectively reduce the error introduced by the “cross-correlation method” . The results using on-orbit data of high-spectral-resolution infrared atmospheric sounder (HIRAS), which was firstly carried on the Fengyun 3D (FY-3D) satellite, showed that the instrument observation error and radiative transfer model simulation error are also needed to be considered in practical data applications to achieve the best spectral regions. Finally the best reference spectral regions for HIRAS spectral accuracy evaluation were obtained, located in 716-766 cm-1 for LW band, 1 〖KG-*5〗270-1 〖KG-*5〗320 cm-1 for MW band and 2 〖KG-*5〗159-2 〖KG-*5〗209 cm-1 for SW band, respectively. The mean spectral bias results based on the selected best reference spectra regions for HIRAS are all less than 2 ppm for the three bands, spectral bias standard deviations are less than 2 ppm for LW and MW bands, and about 4 ppm for SW band. The obtained best spectral regions are also applicable to the spectral frequency accuracy evaluation and long-term frequency monitoring of other infrared interference instruments.
Accurate evaluation and monitoring of spectral frequency accuracy is significant for an hyper-spectral infrared (IR) interferometer before data application. A “cross-correlation method” is commonly used to evaluate the accuracy of the spectral accuracy, which allows the maximum correlation, or minimum standard deviation condition, to be met between an observed and a simulated spectrum by shifting the observed spectrum. From the perspective of the time-consuming calculation, it is not necessary to detect the frequency offset in the entire spectrum, but to evaluate the accuracy of the spectral calibration with a part of the spectral region. To comprehensively evaluate the dependence of the “cross-correlation method” on spectral regions, a preliminary selection of spectral regions was carried out based on the sensitivity analysis of the simulated spectra (with only the off-axis effect of the instrument considered), and the optimal spectral region was selected based on the sensitivity analysis of the on-orbit data. The results based on simulated spectra showed that spectral region selection is sensitive to the evaluation method in long-wave (LW) and short-wave (SW) bands, but insensitive in mid-wave (MW) band. In addition, the sensitivity is rela-ted to the envelope characteristics and to the radiation energy of the absorption line in the spectral regions. The absolute errors for selecting different spectral regions can reach 3.05 and 3.35 ppm (1 ppm=10-6) in LW and SW bands, respectively. Selecting high-radiation-energy and stable atmospheric composition regions can effectively reduce the error introduced by the “cross-correlation method” . The results using on-orbit data of high-spectral-resolution infrared atmospheric sounder (HIRAS), which was firstly carried on the Fengyun 3D (FY-3D) satellite, showed that the instrument observation error and radiative transfer model simulation error are also needed to be considered in practical data applications to achieve the best spectral regions. Finally the best reference spectral regions for HIRAS spectral accuracy evaluation were obtained, located in 716-766 cm-1 for LW band, 1 〖KG-*5〗270-1 〖KG-*5〗320 cm-1 for MW band and 2 〖KG-*5〗159-2 〖KG-*5〗209 cm-1 for SW band, respectively. The mean spectral bias results based on the selected best reference spectra regions for HIRAS are all less than 2 ppm for the three bands, spectral bias standard deviations are less than 2 ppm for LW and MW bands, and about 4 ppm for SW band. The obtained best spectral regions are also applicable to the spectral frequency accuracy evaluation and long-term frequency monitoring of other infrared interference instruments.
2020, 46(6):745-752.
DOI: 10.7519/j.issn.1000-0526.2020.06.002
Abstract:
From 15 October to 15 November 2017, two types of millimeter wave cloud radar (MMCR)(HT101, HMBKPS) installed on the “Science” marine science research ship were used for cloud observation in the West Pacific. Sounding balloons were released periodically during the observation; the accuracy of MMCR was analyzed according to the height of sounding out of cloud and into cloud. A visible light and thermal infrared dualband sky imager was also installed on the ship to obtain 24 h zenith image and MMCR data acquisition rate was analyzed by these images. The test results show that the data of two radars were highly consistent, the cloud base height correlation coefficient was 0.997, and cloud top height correlation coefficient was 0.988. The accuracy of cloud height observation by two types of MMCR was high; the average deviations of cloud base height between sounding and MMCR were 130 m (HT101) and 72 m (HMBKPS); the average deviations of cloud top height between sounding and MMCR were 310 m (HT101) and 190 m (HMBKPS), respectively. Affected by maritime climate and ship swaying, the cloud data acquisition rates of the two MMCR were 57.8% (HT101) and 68.7% (HMBKPS), respectively, and the missed clouds were mainly cirrus and cumulus clouds.
From 15 October to 15 November 2017, two types of millimeter wave cloud radar (MMCR)(HT101, HMBKPS) installed on the “Science” marine science research ship were used for cloud observation in the West Pacific. Sounding balloons were released periodically during the observation; the accuracy of MMCR was analyzed according to the height of sounding out of cloud and into cloud. A visible light and thermal infrared dualband sky imager was also installed on the ship to obtain 24 h zenith image and MMCR data acquisition rate was analyzed by these images. The test results show that the data of two radars were highly consistent, the cloud base height correlation coefficient was 0.997, and cloud top height correlation coefficient was 0.988. The accuracy of cloud height observation by two types of MMCR was high; the average deviations of cloud base height between sounding and MMCR were 130 m (HT101) and 72 m (HMBKPS); the average deviations of cloud top height between sounding and MMCR were 310 m (HT101) and 190 m (HMBKPS), respectively. Affected by maritime climate and ship swaying, the cloud data acquisition rates of the two MMCR were 57.8% (HT101) and 68.7% (HMBKPS), respectively, and the missed clouds were mainly cirrus and cumulus clouds.
2020, 46(6):753-764.
DOI: 10.7519/j.issn.1000-0526.2020.06.003
Abstract:
Precipitation forecast of three typhoon rainfall processes affecting Henan Area in August 2018 from four numerical models, SHANGHAI_HR(SH), GRAPES_MESO(MESO), ECMWF_HR(EC), GRAPES_GFS(GFS) were evaluated using FSS (fractional skill score) and CRA (contiguous rain area) methods based on CMA radar-satellite-gauge merged precipitation (CMPA_Hourly V2.1) in this paper. The difference of two methods and the performance of each numerical model were discussed. The results show that FSS method can better distinguish the performance of different models through quantitive scores compared with the traditional TS method, and CRA method can reflect error sources of models more comprehensively. For local heavy rainfall or intense center of large-scale precipitation, regional models are more superior to global models. However, global models still perform well in 〖JP2〗predicting small-scale precipi-〖JP〗tation. For the two precipitation processes of typhoons ‘Yagi’ and ‘Rumbia’, the displacement errors of EC are more westward than the observation, and the same characteristics are also found in the prediction of ‘Rumbia’ precipitation by MESO and GFS. Precipitation scope and intensity tend to be underestimated by GFS model. The EC model can perform better a little, but still has some shortcomings in estimating precipitation extremes. Although regional models, especially SH, can forecast more intense precipitation centers, the scope and intensity can be easily overestimated. The displacement error for most models is main source of precipitation error, and intensity error and pattern error are roughly equivalent.
Precipitation forecast of three typhoon rainfall processes affecting Henan Area in August 2018 from four numerical models, SHANGHAI_HR(SH), GRAPES_MESO(MESO), ECMWF_HR(EC), GRAPES_GFS(GFS) were evaluated using FSS (fractional skill score) and CRA (contiguous rain area) methods based on CMA radar-satellite-gauge merged precipitation (CMPA_Hourly V2.1) in this paper. The difference of two methods and the performance of each numerical model were discussed. The results show that FSS method can better distinguish the performance of different models through quantitive scores compared with the traditional TS method, and CRA method can reflect error sources of models more comprehensively. For local heavy rainfall or intense center of large-scale precipitation, regional models are more superior to global models. However, global models still perform well in 〖JP2〗predicting small-scale precipi-〖JP〗tation. For the two precipitation processes of typhoons ‘Yagi’ and ‘Rumbia’, the displacement errors of EC are more westward than the observation, and the same characteristics are also found in the prediction of ‘Rumbia’ precipitation by MESO and GFS. Precipitation scope and intensity tend to be underestimated by GFS model. The EC model can perform better a little, but still has some shortcomings in estimating precipitation extremes. Although regional models, especially SH, can forecast more intense precipitation centers, the scope and intensity can be easily overestimated. The displacement error for most models is main source of precipitation error, and intensity error and pattern error are roughly equivalent.
2020, 46(6):765-775.
DOI: 10.7519/j.issn.1000-0526.2020.06.004
Abstract:
Based on NCEP FNL (1°×1°) reanalysis data, observation data from automatic weather stations in Jiangsu Province and new generation weather radar data in Yangtze River Delta area, the cyclone phase space (CPS) method was used to analyze the phase space parameters of typhoons that occurred in Jiangsu from 2000 to 2015. The results show that the CPS method could objectively and accurately describe the transition process of typhoons in Jiangsu affected by various paths according to Typhoon Almanac (CMA-STI). Typhoons affecting the transition of typhoons in Jiangsu are mostly landing northward and show strong intensities before the transition. We further analyze phase space parameters of “Haikui” and “Matmo” with different CPS trajectories. The results show that the phase space parameter can better reflect the evolution of the thermal structure and circulation characteristics during the transition process of typhoon, and it is related to the location and intensity of typhoon precipitation. “Haikui” with obvious changes of CPS parameter has significant variations in the location and intensity of typhoon precipitation. “Matmo” with small CPS parameter changing basically has rains around the typhoon itself.
Based on NCEP FNL (1°×1°) reanalysis data, observation data from automatic weather stations in Jiangsu Province and new generation weather radar data in Yangtze River Delta area, the cyclone phase space (CPS) method was used to analyze the phase space parameters of typhoons that occurred in Jiangsu from 2000 to 2015. The results show that the CPS method could objectively and accurately describe the transition process of typhoons in Jiangsu affected by various paths according to Typhoon Almanac (CMA-STI). Typhoons affecting the transition of typhoons in Jiangsu are mostly landing northward and show strong intensities before the transition. We further analyze phase space parameters of “Haikui” and “Matmo” with different CPS trajectories. The results show that the phase space parameter can better reflect the evolution of the thermal structure and circulation characteristics during the transition process of typhoon, and it is related to the location and intensity of typhoon precipitation. “Haikui” with obvious changes of CPS parameter has significant variations in the location and intensity of typhoon precipitation. “Matmo” with small CPS parameter changing basically has rains around the typhoon itself.
2020, 46(6):776-791.
DOI: 10.7519/j.issn.1000-0526.2020.06.005
Abstract:
Based on Doppler radar data, automatic weather station data and conventional observation data, the environmental conditions and mesoscale convective system (MCS) in Yichang from 2016 to 2017 were analyzed. The results showed that there are three synoptic situation configurations of extreme flash rain (EFR): baroclinic frontogenesis category, quasi-barotropic category and low-level warm advection forcing category. In the baroclinic frontogenesis environment, the cold front is slower in the central and west of Yichang. The heavy updraft caused by the front, which is stronger, combined with the warm and humid airflow makes MCS high and thick. The strong vertical shear causes hanging structure of the cell. The instantaneous rainfall intensity is stronger and the duration of convection is longer when the airflows are converged and blocked by the terrain, resulting in intermittent and dispersive EFR. The quasi-barotropic type Ⅰ occurs at the inner edge of the subtropical high. The center of convergence formed by the topography with developing of the southerly in the saddle field triggers and strengthens the convective cell, causing heavy instantaneous rain intensity. Extremely, the weak steering flow and the backward propagation effect of the weakening cell in the piedmont area of the downwind side cause the convection to be streng-thened again in the valley area in front of the mountain, resulting in EFR with short time, very small range and heavy rain intensity. The quasi-barotropic type Ⅱ occurs at the convergence of the warm moist easterly and northerly flow of the boundary layer while the easterly wave moves to west, resulting in heavy precipitation tower deep echoes with ultra-low center of mass. The topographical transition zone on the east side of the mountain merges the northerly wind and the easterly wind several times, causing the EFR with relatively small intensity, larger area and lasting several times. In the warm advection forcing environment, a convergence line is formed with the strengthening of southwestern jet. The deep and strong echoes inclined downstream are arranged along the convergence line. The shear line and convergence line are in accord with the trend of rain band and the “train-effect” appears on the convection line, causing the cell to be regenerated and strengthened, moving downstream in the upstream of the convection line. So the line EFR with discontinuity distribution appears some times in a row on the convection line.
Based on Doppler radar data, automatic weather station data and conventional observation data, the environmental conditions and mesoscale convective system (MCS) in Yichang from 2016 to 2017 were analyzed. The results showed that there are three synoptic situation configurations of extreme flash rain (EFR): baroclinic frontogenesis category, quasi-barotropic category and low-level warm advection forcing category. In the baroclinic frontogenesis environment, the cold front is slower in the central and west of Yichang. The heavy updraft caused by the front, which is stronger, combined with the warm and humid airflow makes MCS high and thick. The strong vertical shear causes hanging structure of the cell. The instantaneous rainfall intensity is stronger and the duration of convection is longer when the airflows are converged and blocked by the terrain, resulting in intermittent and dispersive EFR. The quasi-barotropic type Ⅰ occurs at the inner edge of the subtropical high. The center of convergence formed by the topography with developing of the southerly in the saddle field triggers and strengthens the convective cell, causing heavy instantaneous rain intensity. Extremely, the weak steering flow and the backward propagation effect of the weakening cell in the piedmont area of the downwind side cause the convection to be streng-thened again in the valley area in front of the mountain, resulting in EFR with short time, very small range and heavy rain intensity. The quasi-barotropic type Ⅱ occurs at the convergence of the warm moist easterly and northerly flow of the boundary layer while the easterly wave moves to west, resulting in heavy precipitation tower deep echoes with ultra-low center of mass. The topographical transition zone on the east side of the mountain merges the northerly wind and the easterly wind several times, causing the EFR with relatively small intensity, larger area and lasting several times. In the warm advection forcing environment, a convergence line is formed with the strengthening of southwestern jet. The deep and strong echoes inclined downstream are arranged along the convergence line. The shear line and convergence line are in accord with the trend of rain band and the “train-effect” appears on the convection line, causing the cell to be regenerated and strengthened, moving downstream in the upstream of the convection line. So the line EFR with discontinuity distribution appears some times in a row on the convection line.
2020, 46(6):792-800.
DOI: 10.7519/j.issn.1000-0526.2020.06.006
Abstract:
Based on denselyobserved surface and radar data and NCEP FNL data as well as the best track data from Shanghai Typhoon Institute/CMA, this article examines the structure and evolution of the rainbands of Typhoon Rumbia that caused torrential rain in East China after Rumbia moved far into inland. The results show that the rainbands twice manifested evolutions from multiple short rainbands into a single long rainband respectively around the boundaries between Shandong, Henan and Anhui provinces as well as midsouthern Shandong Province. The maintenance and evolution of the rainbands were determined mainly by the sustaining of typhoon circulation and intensity and its interaction with the stagnation and westward extension of subtropical high. Because of the intensification of lowlevel vertical wind shear, the rainbands displayed apparent convective features with embedded tornadoes in northern Anhui and south Shandong.
Based on denselyobserved surface and radar data and NCEP FNL data as well as the best track data from Shanghai Typhoon Institute/CMA, this article examines the structure and evolution of the rainbands of Typhoon Rumbia that caused torrential rain in East China after Rumbia moved far into inland. The results show that the rainbands twice manifested evolutions from multiple short rainbands into a single long rainband respectively around the boundaries between Shandong, Henan and Anhui provinces as well as midsouthern Shandong Province. The maintenance and evolution of the rainbands were determined mainly by the sustaining of typhoon circulation and intensity and its interaction with the stagnation and westward extension of subtropical high. Because of the intensification of lowlevel vertical wind shear, the rainbands displayed apparent convective features with embedded tornadoes in northern Anhui and south Shandong.
2020, 46(6):801-812.
DOI: 10.7519/j.issn.1000-0526.2020.06.007
Abstract:
Based on the hourly precipitation data of more than 2000 regional automatic weather stations during 2003-2017 in Guangdong， the characteristics of the annual and monthly variations of extremely severe 〖JP2〗precipitation with different durations in Guangdong were ana〖JP〗lyzed. On this basis, the spatiotemporal distributions of the frequency of extreme precipitation in the flood season from April to September were analyzed. The results showed that there are obvious differences among the annual frequency variation trends of extremely severe precipitation with different durations in Guangdong in the last 15 years. The frequency of 24 h precipitation tends to decrease in the annual, the first and the second flood seasons but those of the 3 h and 1 h precipitation increase. The frequency of 1 h extremely severe precipitation shows a significant increase in the annual and the second flood season. May-June is 〖JP2〗the most prone period for extreme precipi〖JP〗tation in Guangdong, whose frequency is mainly found in Yangjiang, Jiangmen and Maoming in the southwest of Guangdong, Guangzhou and Qingyuan in the central and northern parts, as well as Shantou and Jieyang in the east of Guangdong. The extremly severe precipitation in the second flood season is mainly seen in the southcentral region, especially in the southern coast of Guangdong. The number of extremely severe precipitation for 1 h shows an increasing trend in the Pearl River Delta, Xinyi of Maoming and Gaozhou, while the trend for most of the eastern Guangdong decreases. Terrain and atmospheric circulation may be the important factors for the frequency center of extremely severe precipitation in Guangdong.
Based on the hourly precipitation data of more than 2000 regional automatic weather stations during 2003-2017 in Guangdong， the characteristics of the annual and monthly variations of extremely severe 〖JP2〗precipitation with different durations in Guangdong were ana〖JP〗lyzed. On this basis, the spatiotemporal distributions of the frequency of extreme precipitation in the flood season from April to September were analyzed. The results showed that there are obvious differences among the annual frequency variation trends of extremely severe precipitation with different durations in Guangdong in the last 15 years. The frequency of 24 h precipitation tends to decrease in the annual, the first and the second flood seasons but those of the 3 h and 1 h precipitation increase. The frequency of 1 h extremely severe precipitation shows a significant increase in the annual and the second flood season. May-June is 〖JP2〗the most prone period for extreme precipi〖JP〗tation in Guangdong, whose frequency is mainly found in Yangjiang, Jiangmen and Maoming in the southwest of Guangdong, Guangzhou and Qingyuan in the central and northern parts, as well as Shantou and Jieyang in the east of Guangdong. The extremly severe precipitation in the second flood season is mainly seen in the southcentral region, especially in the southern coast of Guangdong. The number of extremely severe precipitation for 1 h shows an increasing trend in the Pearl River Delta, Xinyi of Maoming and Gaozhou, while the trend for most of the eastern Guangdong decreases. Terrain and atmospheric circulation may be the important factors for the frequency center of extremely severe precipitation in Guangdong.
2020, 46(6):813-822.
DOI: 10.7519/j.issn.1000-0526.2020.06.008
Abstract:
This article calculated the Zindex by using the monthly 〖JP2〗precipitation data over the Songhua River〖JP〗 Basin from 1961 to 2017, and also analyzed the climatological characteristics and interdecadal variations of the summer rain waterlogging over the Songhua River Basin and the relationship with the climate system index. The results are as follows. Waterlogging tends to occur most in the main stream of the Songhua River in summer (12 in 30 years), 〖JP2〗then in the upper reaches of the Nenjiang River (11 years), and the least in the Xiao Hinggan Mountains area (7 years). However, 〖JP〗the Xiao Hinggan Mountains have the highest intensity of waterlogging (average 2.1 a-1), followed by the upstream of Songhua River (1.8 a-1), and in Zhangguangcai Mountains it is the smallest (1.4 a-1). The waterlogging occurs most in June in the Songhua River Basin, and least in August. The average rain intensity of waterlogging is the highest in August and the smallest in July. In the summer and July of 1961-2017, the waterlogging over the lower reaches of the Nenjiang River gets weakened significantly. In June, the intensity of waterlogging in the Xiao Hinggan Mountains increases apparently. The summer waterlogging events in the Songhua River Basin are affected by atmospheric circulation and oceanic factors during the previous period.
This article calculated the Zindex by using the monthly 〖JP2〗precipitation data over the Songhua River〖JP〗 Basin from 1961 to 2017, and also analyzed the climatological characteristics and interdecadal variations of the summer rain waterlogging over the Songhua River Basin and the relationship with the climate system index. The results are as follows. Waterlogging tends to occur most in the main stream of the Songhua River in summer (12 in 30 years), 〖JP2〗then in the upper reaches of the Nenjiang River (11 years), and the least in the Xiao Hinggan Mountains area (7 years). However, 〖JP〗the Xiao Hinggan Mountains have the highest intensity of waterlogging (average 2.1 a-1), followed by the upstream of Songhua River (1.8 a-1), and in Zhangguangcai Mountains it is the smallest (1.4 a-1). The waterlogging occurs most in June in the Songhua River Basin, and least in August. The average rain intensity of waterlogging is the highest in August and the smallest in July. In the summer and July of 1961-2017, the waterlogging over the lower reaches of the Nenjiang River gets weakened significantly. In June, the intensity of waterlogging in the Xiao Hinggan Mountains increases apparently. The summer waterlogging events in the Songhua River Basin are affected by atmospheric circulation and oceanic factors during the previous period.
2020, 46(6):823-836.
DOI: 10.7519/j.issn.1000-0526.2020.06.009
Abstract:
Based on the statistical analysis of echo structure of severe convective storms in Guangzhou du-ring 2015-2017, a network of phased-array polarimetric Doppler radar has been set up, which can entirely cover the central district of Guangzhou. The main purpose is to obtain high-resolution radar datasets of severe meso- and micro-scale convections, which would be helpful for further analyzing structure and the formation, dispersal mechanism of these storms. Meanwhile, it could contribute to understanding the effects of urban canopy on the local meteorological field and the linear convection systems such as squall lines. The results of field experiment show that the high-resolution radar datasets from phased-array radar have great advantages in monitoring development of local meso- and micro-scale convections, and the evolution of local intensity of linear convection systems. It would greatly help to increase the accuracy and timeliness of early warning and other operations. The poor side is that the phased-array radar scans with a single beam, which makes it difficult to further accelerate the scanning speed.
Based on the statistical analysis of echo structure of severe convective storms in Guangzhou du-ring 2015-2017, a network of phased-array polarimetric Doppler radar has been set up, which can entirely cover the central district of Guangzhou. The main purpose is to obtain high-resolution radar datasets of severe meso- and micro-scale convections, which would be helpful for further analyzing structure and the formation, dispersal mechanism of these storms. Meanwhile, it could contribute to understanding the effects of urban canopy on the local meteorological field and the linear convection systems such as squall lines. The results of field experiment show that the high-resolution radar datasets from phased-array radar have great advantages in monitoring development of local meso- and micro-scale convections, and the evolution of local intensity of linear convection systems. It would greatly help to increase the accuracy and timeliness of early warning and other operations. The poor side is that the phased-array radar scans with a single beam, which makes it difficult to further accelerate the scanning speed.
2020, 46(6):837-849.
DOI: 10.7519/j.issn.1000-0526.2020.06.010
Abstract:
Based on pollutantion data from environmental monitoring stations, observation data from surface automatic weather stations, L-band dense sounding data and EC 0.125°×0.125° reanalysis data, and combined with fire point data from satellite remote sensing and simulation results of HYSPLIT4 backward trajectory, this paper analyzes the atmospheric boundary layer features, diffusion and transport meteorological conditions of two serious pollution events in Liaoning Province caused by crop residue burning of Northeast China on 8 November 2015 and 5 November 2016. The result shows that PM2.5 concentrations increased and decreased rapidly during the two pollution 〖JP2〗events. The serious pollution event on 8 November 2015 had stronger intensity and longer duration than the event on 5 November 2016. In the 8 November 2015 event, the mixing layer height was lower, on which neutral layer changed into inversion layer restraining the development of mixing layer height. At the same time, the cold advection in lower layer invaded below warm advection in higher layer, making the atmosphere more stable and lasting longer. The enhanced vertical subsidence motion and long-distance horizontal regional transportation of pollutants in southwestern Heilongjiang and western Jilin provinces resulted in rapid accumulation of pollutants on the surface in Liaoning. Due to stronger cold air, regional transportation in west of Northeast China and surface wind convergence strengthened are the main reason for the rapid increase of pollutant concentration in the event on 5 November 2016.
Based on pollutantion data from environmental monitoring stations, observation data from surface automatic weather stations, L-band dense sounding data and EC 0.125°×0.125° reanalysis data, and combined with fire point data from satellite remote sensing and simulation results of HYSPLIT4 backward trajectory, this paper analyzes the atmospheric boundary layer features, diffusion and transport meteorological conditions of two serious pollution events in Liaoning Province caused by crop residue burning of Northeast China on 8 November 2015 and 5 November 2016. The result shows that PM2.5 concentrations increased and decreased rapidly during the two pollution 〖JP2〗events. The serious pollution event on 8 November 2015 had stronger intensity and longer duration than the event on 5 November 2016. In the 8 November 2015 event, the mixing layer height was lower, on which neutral layer changed into inversion layer restraining the development of mixing layer height. At the same time, the cold advection in lower layer invaded below warm advection in higher layer, making the atmosphere more stable and lasting longer. The enhanced vertical subsidence motion and long-distance horizontal regional transportation of pollutants in southwestern Heilongjiang and western Jilin provinces resulted in rapid accumulation of pollutants on the surface in Liaoning. Due to stronger cold air, regional transportation in west of Northeast China and surface wind convergence strengthened are the main reason for the rapid increase of pollutant concentration in the event on 5 November 2016.
2020, 46(6):850-856.
DOI: 10.7519/j.issn.1000-0526.2020.06.011
Abstract:
Due to the influence of upper-air wind, the actual ballistic trajectory and range of the artificial precipitation of anti-hail rocket are not inconsistent with the theoretical ballistic values. A tracking system of artificial precipitation enhancement and anti-hail rocket for seeding operation was developed in order to scientifically and precisely enhance the operation and accurately evaluate the effect of the seeding. The system consists of rocket positioning and data transmission. It uses satellite positioning module and the data transmission station mode to transmit the rocket flight trajectory to the ground in real time. Two artificial precipitation enhancement and anti-hail rockets were launched to carry out an artificial precipitation enhancement and anti-hail rocket ballistic tracking experiment. The results showed that all data were received completely except for the initial stage of 4-5 seconds without data when the satellite positioning was out of lock. The actual trajectory of the rocket after wind deviation correction is closer to the theoretical one, and the effect is significant, which is conducive to the 〖JP2〗precise operation of the rocket for precipitation enhancement and hail suppression.
Due to the influence of upper-air wind, the actual ballistic trajectory and range of the artificial precipitation of anti-hail rocket are not inconsistent with the theoretical ballistic values. A tracking system of artificial precipitation enhancement and anti-hail rocket for seeding operation was developed in order to scientifically and precisely enhance the operation and accurately evaluate the effect of the seeding. The system consists of rocket positioning and data transmission. It uses satellite positioning module and the data transmission station mode to transmit the rocket flight trajectory to the ground in real time. Two artificial precipitation enhancement and anti-hail rockets were launched to carry out an artificial precipitation enhancement and anti-hail rocket ballistic tracking experiment. The results showed that all data were received completely except for the initial stage of 4-5 seconds without data when the satellite positioning was out of lock. The actual trajectory of the rocket after wind deviation correction is closer to the theoretical one, and the effect is significant, which is conducive to the 〖JP2〗precise operation of the rocket for precipitation enhancement and hail suppression.
2020, 46(6):857-862.
DOI: 10.7519/j.issn.1000-0526.2020.06.012
Abstract:
Based on daily meteorological data from 62 stations from late July to early September during 1981 to 2018, and the meteorological industry standard Temperature Index of High Temperature Harm for Main Crops, the single-station and regional disaster-causing index of single-season-rice heat injury were divided. According to the regional index, three provincial grades were classified: i.e., light, medium and severe. In addition, the variation of single-season-rice heat injury in Anhui Province in the recent 40 years was analyzed. The results show that, the coincidence rate of historical test of disaster grade reached 97%. It can be used to quantitatively evaluate the effect of heat injury on single-season-rice in the whole province or in a region. Thus, this index can be applied to the operational services of single-season-rice yield prediction and disaster assessment in Anhui Province.
Based on daily meteorological data from 62 stations from late July to early September during 1981 to 2018, and the meteorological industry standard Temperature Index of High Temperature Harm for Main Crops, the single-station and regional disaster-causing index of single-season-rice heat injury were divided. According to the regional index, three provincial grades were classified: i.e., light, medium and severe. In addition, the variation of single-season-rice heat injury in Anhui Province in the recent 40 years was analyzed. The results show that, the coincidence rate of historical test of disaster grade reached 97%. It can be used to quantitatively evaluate the effect of heat injury on single-season-rice in the whole province or in a region. Thus, this index can be applied to the operational services of single-season-rice yield prediction and disaster assessment in Anhui Province.
2020, 46(6):863-872.
DOI: 10.7519/j.issn.1000-0526.2020.06.013
Abstract:
The main characteristics of the general atmospheric circulation in March 2020 are as follows. One polar vortex center was located towards Asia and stronger than usual. The circulation at middle-high latitudes of the Eurasia showed a three-wave pattern, and the East Asian trough was shallow. The Western Pacific subtropical high was stronger than the climatological normal, while the Bay of Bengal trough was equal to usual. Cold airs that affected China were generally frequent but not strong, causing a significant warming in most areas in March. The monthly mean temperature was 6.1℃, higher than normal (4.1℃) by 2℃, and the highest temperature observed at 58 stations broke the historical extreme values. In addition, weak cold air frequently penetrated southwards and cooperated with the activities of the Bay of Bengal trough, resulting in continuous rainy weather in southern China. The monthly mean precipitation amount across China was 35.0 mm, more than the normal by 18.4%. Three nationwide strong cold air processes happened in this month. Under the warmer background in the previous period, 91 stations experienced daily extreme drops in temperature. There were seven rainfall processes in the southern region, three of which were accompanied by obvious severe convective weather. Several provinces were attacked by severe thunderstorms and hail disaster. In addition, four sand-dust weather events occurred in northern China, while severe droughts were found in the east of Sichuan, southern Shaanxi and Yunnan provinces.
The main characteristics of the general atmospheric circulation in March 2020 are as follows. One polar vortex center was located towards Asia and stronger than usual. The circulation at middle-high latitudes of the Eurasia showed a three-wave pattern, and the East Asian trough was shallow. The Western Pacific subtropical high was stronger than the climatological normal, while the Bay of Bengal trough was equal to usual. Cold airs that affected China were generally frequent but not strong, causing a significant warming in most areas in March. The monthly mean temperature was 6.1℃, higher than normal (4.1℃) by 2℃, and the highest temperature observed at 58 stations broke the historical extreme values. In addition, weak cold air frequently penetrated southwards and cooperated with the activities of the Bay of Bengal trough, resulting in continuous rainy weather in southern China. The monthly mean precipitation amount across China was 35.0 mm, more than the normal by 18.4%. Three nationwide strong cold air processes happened in this month. Under the warmer background in the previous period, 91 stations experienced daily extreme drops in temperature. There were seven rainfall processes in the southern region, three of which were accompanied by obvious severe convective weather. Several provinces were attacked by severe thunderstorms and hail disaster. In addition, four sand-dust weather events occurred in northern China, while severe droughts were found in the east of Sichuan, southern Shaanxi and Yunnan provinces.
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ISSN:1000-0526 CN:11-2282/P