ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 48,Issue 10,2022 Table of Contents
2022, 48(10):1217-1229.
DOI: 10.7519/j.issn.1000-0526.2022.051701
Abstract:
The ratio of transpiration to evapotranspiration (T/ET) is a key parameter to illustrate the role of vegetation in controlling water loss in terrestrial systems. Quantifying evapotranspiration and its components is a key to understand the dynamics and mechanism of evapotranspiration and it is the basis for studying the eco-hydrological process. This paper reviews the research progress of T/ET quantification methods (measurement methods and model methods), T/ET results in different ecosystems and their driving mechanisms (climate change and vegetation cover). The methods are introduced in T/ET observation and simulation developed at home and aboard, and the results of different methods are compared. The values of T/ET are described in four types of terrestrial ecosystems, including forest, grassland, wetland and farmland. There are significant differences in T/ET in the same or even in the different ecosystems, which are mainly due to the differences in ecosystem types, spatial and temporal scales, selection of data set, observation and simulation methods. The main driving mechanisms of T/ET included vegetation type, vegetation cover, climate factors and soil factors. In the future, uncertainty studies around different quantification methods of T/ET, changing patterns and driving mechanisms of T/ET in different terrestrial ecosystems will be emphasized.
The ratio of transpiration to evapotranspiration (T/ET) is a key parameter to illustrate the role of vegetation in controlling water loss in terrestrial systems. Quantifying evapotranspiration and its components is a key to understand the dynamics and mechanism of evapotranspiration and it is the basis for studying the eco-hydrological process. This paper reviews the research progress of T/ET quantification methods (measurement methods and model methods), T/ET results in different ecosystems and their driving mechanisms (climate change and vegetation cover). The methods are introduced in T/ET observation and simulation developed at home and aboard, and the results of different methods are compared. The values of T/ET are described in four types of terrestrial ecosystems, including forest, grassland, wetland and farmland. There are significant differences in T/ET in the same or even in the different ecosystems, which are mainly due to the differences in ecosystem types, spatial and temporal scales, selection of data set, observation and simulation methods. The main driving mechanisms of T/ET included vegetation type, vegetation cover, climate factors and soil factors. In the future, uncertainty studies around different quantification methods of T/ET, changing patterns and driving mechanisms of T/ET in different terrestrial ecosystems will be emphasized.
2022, 48(10):1230-1241.
DOI: 10.7519/j.issn.1000-0526.2022.040102
Abstract:
Based on the surface historical observation data, the statistical analysis of the snow to liquid ratio of the typical winter snowfall events in China is conducted. Then the snow to liquid ratio and fresh snowfall depth forecast models are built using the Cobb method, ECMWF IFS model forecast and the gridded precipitation and its type grid forecast from the National Meteorological Centre. The statistical analysis shows that the snow to liquid ratio in the snowfall events in China is widely distributed, with a minimum of 0.3∶1 and a maximum of 100∶1. Only about 4% of the snow to liquid ratio records are 10∶1. The snow to liquid ratio has obvious regional and seasonal characteristics. The snow to liquid ratios in Xinjiang, eastern Northwest China, North China and Northeast China are larger than those in other regions. The snow to liquid ratio in winter is larger than that in spring and autumn. Based on the modified Cobb method, which can identify the cloud according to topography, the snow to liquid ratio is firstly constructed based on the statistical relationship between the temperature in the cloud and the snow to liquid ratio and the related vertical velocity. The snow to liquid ratio and fresh snowfall depth forecasted by modified Cobb method can reflect the spatial characteristics of the actual snow to liquid ratio in the precipitation process, compared with the original Cobb method. The fresh snowfall depth forecast performance is obtained by combining the snow to liquid ratio forecast model and the National Meteorological Centre’s gridded snowfall forecast and it significantly improves the fresh snowfall depth forecast compared with that by the ECMWF IFS model. In particular, the ability to predict fresh snowfall depth over 20 cm has been significantly improved, and the TS score increase rate of the fresh snowfall depth forecast built in this paper relative to that by the ECMWF IFS model is basically over 10%. At present, this technology has been applied in the National Meteorological Center, providing strong support for winter snowfall forecasting.
Based on the surface historical observation data, the statistical analysis of the snow to liquid ratio of the typical winter snowfall events in China is conducted. Then the snow to liquid ratio and fresh snowfall depth forecast models are built using the Cobb method, ECMWF IFS model forecast and the gridded precipitation and its type grid forecast from the National Meteorological Centre. The statistical analysis shows that the snow to liquid ratio in the snowfall events in China is widely distributed, with a minimum of 0.3∶1 and a maximum of 100∶1. Only about 4% of the snow to liquid ratio records are 10∶1. The snow to liquid ratio has obvious regional and seasonal characteristics. The snow to liquid ratios in Xinjiang, eastern Northwest China, North China and Northeast China are larger than those in other regions. The snow to liquid ratio in winter is larger than that in spring and autumn. Based on the modified Cobb method, which can identify the cloud according to topography, the snow to liquid ratio is firstly constructed based on the statistical relationship between the temperature in the cloud and the snow to liquid ratio and the related vertical velocity. The snow to liquid ratio and fresh snowfall depth forecasted by modified Cobb method can reflect the spatial characteristics of the actual snow to liquid ratio in the precipitation process, compared with the original Cobb method. The fresh snowfall depth forecast performance is obtained by combining the snow to liquid ratio forecast model and the National Meteorological Centre’s gridded snowfall forecast and it significantly improves the fresh snowfall depth forecast compared with that by the ECMWF IFS model. In particular, the ability to predict fresh snowfall depth over 20 cm has been significantly improved, and the TS score increase rate of the fresh snowfall depth forecast built in this paper relative to that by the ECMWF IFS model is basically over 10%. At present, this technology has been applied in the National Meteorological Center, providing strong support for winter snowfall forecasting.
HOU Shumei
,
LI Yuwei
,
ZHANG Peng
,
ZHU Xiaoqing
,
GAO Rongzhen
,
ZHANG Yongjing
,
MEI Chanjuan
,
SHI Lei
,
ZHU Yiqing
2022, 48(10):1242-1256.
DOI: 10.7519/j.issn.1000-0526.2022.041801
Abstract:
The thunderstorm gale as powerful as grade (10-13) overturned a fishing ship along the Shandong Coast on 29 April 2021. The causes of this thunderstorm gale process are investigated in this paper based on the data of Doppler weather radar and densely-distributed automatic weather station, ERA5 reanalysis data and the conventional observation data. The results show that the cold and dry air coming from northwest behind the northeast China cold vortex superimposed the lower-level warm ridge, and the strong potential instability stratification and vertical wind shear provided favorable environmental conditions for this severe convection weather. Under the influence of the strong upper-level northwest steering currents, the advection of both the Qingdao thunderstorm and the gust front were fast, and the angular momentum of downdraft was increased due to momentum downward-transporting. The gust front lasted for a long time and moved fast, directly causing thunderstorm gale of grade 10-13 to hit the places it passed through. Dry air in the middle-low troposphere and evaporative cooling of upper-level hydrometeor during its falling process, formed a cold pool with thickness up to 120 hPa near the ground. Allobaric wind formed between the pressurization area at the rear of the large-scale cyclone superimposed with the small-scale cold pool and the decompression area of the cyclone. Density currents between the cold pool and warm ridge in Rizhao superimposed with allobaric wind led to enhancement of surface wind. Considering the orientation of the pressure gradient changed after the high pressure cold-core entering sea. Wind direction became rotated so that the risk of fishing boat overturning increased. The evaporation, gradient of the frontal zone, intensity of density flow and superposition effect of the multi-scale weather system over Rizhao, were all stronger than those in Qingdao, so that the thunderstorm gales above grade 10 in Rizhao City, which lay on the edge of Qingdao thunderstorm, had a greater power and scope than those in Qingdao City, that was affected by the main body of the thunderstorm.
The thunderstorm gale as powerful as grade (10-13) overturned a fishing ship along the Shandong Coast on 29 April 2021. The causes of this thunderstorm gale process are investigated in this paper based on the data of Doppler weather radar and densely-distributed automatic weather station, ERA5 reanalysis data and the conventional observation data. The results show that the cold and dry air coming from northwest behind the northeast China cold vortex superimposed the lower-level warm ridge, and the strong potential instability stratification and vertical wind shear provided favorable environmental conditions for this severe convection weather. Under the influence of the strong upper-level northwest steering currents, the advection of both the Qingdao thunderstorm and the gust front were fast, and the angular momentum of downdraft was increased due to momentum downward-transporting. The gust front lasted for a long time and moved fast, directly causing thunderstorm gale of grade 10-13 to hit the places it passed through. Dry air in the middle-low troposphere and evaporative cooling of upper-level hydrometeor during its falling process, formed a cold pool with thickness up to 120 hPa near the ground. Allobaric wind formed between the pressurization area at the rear of the large-scale cyclone superimposed with the small-scale cold pool and the decompression area of the cyclone. Density currents between the cold pool and warm ridge in Rizhao superimposed with allobaric wind led to enhancement of surface wind. Considering the orientation of the pressure gradient changed after the high pressure cold-core entering sea. Wind direction became rotated so that the risk of fishing boat overturning increased. The evaporation, gradient of the frontal zone, intensity of density flow and superposition effect of the multi-scale weather system over Rizhao, were all stronger than those in Qingdao, so that the thunderstorm gales above grade 10 in Rizhao City, which lay on the edge of Qingdao thunderstorm, had a greater power and scope than those in Qingdao City, that was affected by the main body of the thunderstorm.
2022, 48(10):1257-1269.
DOI: 10.7519/j.issn.1000-0526.2022.013001
Abstract:
Under the similar atmospheric circulation backgrounds, the precipitation characteristics along the coast of Guangdong on 2 and 3 June 2020 are quite different, so the mechanism is worthy of deeply exploring. Based on ERA5 reanalysis data, wind profile radar products and observation data, we comparatively analyze the differences of precipitation, atmospheric circulation and physical quantity field in the warm sector of western Guangdong coast in the two days. Besides, we also discuss the trigger and maintenance mechanism of the double low-level jets for the precipitation in the warm sector of the region. The main conclusions are as follows. The low-level southwest jet axis was located in eastern part of Guangxi, the boundary layer southerly jet over the northwest of the South China Sea strengthened at night and its front side reached the coast of western Guangdong, maintaining for a long time. Under such a condition, the dynamic convergence and uplift caused by the convergence of wind speed in the front of the boundary layer southerly jet and the blocking effect of the coastal terrain of western Guangdong on the southward flow were conducive to the occurrence of convection in this area. At the same time, the existence and maintenance of cold pool favored the development and maintenance of rainstorm in the coastal warm sector of western Guangdong. When the low-level jet was significantly strengthened, expanding to the east and retracting to the north, and the boundary layer jet turned to the southwest extending to the north of the Pearl River Delta, the condition is not beneficial to the triggering and development of convection in the west coast of Guangdong.
Under the similar atmospheric circulation backgrounds, the precipitation characteristics along the coast of Guangdong on 2 and 3 June 2020 are quite different, so the mechanism is worthy of deeply exploring. Based on ERA5 reanalysis data, wind profile radar products and observation data, we comparatively analyze the differences of precipitation, atmospheric circulation and physical quantity field in the warm sector of western Guangdong coast in the two days. Besides, we also discuss the trigger and maintenance mechanism of the double low-level jets for the precipitation in the warm sector of the region. The main conclusions are as follows. The low-level southwest jet axis was located in eastern part of Guangxi, the boundary layer southerly jet over the northwest of the South China Sea strengthened at night and its front side reached the coast of western Guangdong, maintaining for a long time. Under such a condition, the dynamic convergence and uplift caused by the convergence of wind speed in the front of the boundary layer southerly jet and the blocking effect of the coastal terrain of western Guangdong on the southward flow were conducive to the occurrence of convection in this area. At the same time, the existence and maintenance of cold pool favored the development and maintenance of rainstorm in the coastal warm sector of western Guangdong. When the low-level jet was significantly strengthened, expanding to the east and retracting to the north, and the boundary layer jet turned to the southwest extending to the north of the Pearl River Delta, the condition is not beneficial to the triggering and development of convection in the west coast of Guangdong.
2022, 48(10):1270-1280.
DOI: 10.7519/j.issn.1000-0526.2022.042601
Abstract:
Based on the observation data of Ka band scanning millimeter-wave radar and automatic weather station, the sea fog remote sensing experiment was carried out in coastal area of Pingtan, Fujian Province. The characteristics of six sea fog processes that occurred from May 2020 to March 2021 were analyzed, and visibility inversion in fog area was carried out based on millimeter-wave radar. The results showed that the millimeter-wave radar can effectively detect the horizontal distribution and vertical structure of sea fog, and can be used to monitor the evolution of sea fog. In the flourishing stage of sea fog, the reflectivity factor of millimeter-wave radar shows a strong filamile-like echo structure extending from the top of fog layer to the surface. The radar reflectivity factor of sea fog is negatively correlated with the forward-scatter visibility, but for each sea fog process, the relation between the radar reflectivity factor and the forward-scatter visibility does not follow a clear general equation. The radar reflectivity factor of sea fog is concentrated in the range from -30 dBz to -10 dBz, and the frequency histogram accords with normal distribution. The echo of fog area is uniform on the whole, but the dynamic range of reflectivity factor is large in fog generation and dissipation stage, while the dynamic range is small in fog persistence stage. The retrieved visibility by millimeter-wave radar and the forward-scatter visibility have relatively consistent fluctuations, which could reflect the change of visibility in fog area, but different cases present different features.
Based on the observation data of Ka band scanning millimeter-wave radar and automatic weather station, the sea fog remote sensing experiment was carried out in coastal area of Pingtan, Fujian Province. The characteristics of six sea fog processes that occurred from May 2020 to March 2021 were analyzed, and visibility inversion in fog area was carried out based on millimeter-wave radar. The results showed that the millimeter-wave radar can effectively detect the horizontal distribution and vertical structure of sea fog, and can be used to monitor the evolution of sea fog. In the flourishing stage of sea fog, the reflectivity factor of millimeter-wave radar shows a strong filamile-like echo structure extending from the top of fog layer to the surface. The radar reflectivity factor of sea fog is negatively correlated with the forward-scatter visibility, but for each sea fog process, the relation between the radar reflectivity factor and the forward-scatter visibility does not follow a clear general equation. The radar reflectivity factor of sea fog is concentrated in the range from -30 dBz to -10 dBz, and the frequency histogram accords with normal distribution. The echo of fog area is uniform on the whole, but the dynamic range of reflectivity factor is large in fog generation and dissipation stage, while the dynamic range is small in fog persistence stage. The retrieved visibility by millimeter-wave radar and the forward-scatter visibility have relatively consistent fluctuations, which could reflect the change of visibility in fog area, but different cases present different features.
2022, 48(10):1281-1291.
DOI: 10.7519/j.issn.1000-0526.2022.032401
Abstract:
In this paper, the correlation between air pollution and meteorological elements and the configuration of high- and low-altitude weather systems in Jinan City is discussed, a synoptic conceptual model of Jinan air pollution is formed, and the effects of cold air processes of different intensities on the generation and elimination of air pollutants in Jinan City are studied. The results show that during 2016-2018 more than 75% of PM2.5 pollution episodes in Jinan City occurred in the surface uniform pressure field. If the occurrence probability of each weather pattern was equal, the surface weather pattern with the highest occurrence probability of pollution episodes was the inverted trough pattern (>55%), followed by the uniform pressure field pattern (26.8%). Moreover, there was a more than 25% occurrence probability of PM2.5 pollution when the 500 hPa circulation was controlled by such weather systems, i.e., the ridge, straight westerlies, anticyclone, behind the trough and in front of the trough. The circulation configuration at upper and lower levels with the greatest probability of PM2.5 pollution (>50%) in Jinan City was the type of the surface inverted trough and behind the upper-level trough, followed by the type of the surface inverted trough and the upper-level straight westerlies, and the type of the surface uniform pressure field and behind the upper-level trough. For the average, the mixed layer height was below 1000 m during PM2.5 pollution episodes and was less than 800 m under heavy pollution. During pollution periods, the average relative humidity is 65%±20%, and the average temperature was 6℃±1℃. The effect of cold air with different intensities on the pollutant episodes was complex. The stronger cold air (ΔT24 h>4.3℃, Δp24 h>4.74 hPa) with a certain duration, such as the northerly wind greater than 3.5 m·s-1 lasting more than 9.6 h, can remove pollutants completely. The slightly weaker cold air may be beneficial to reduce pollutant concentration. However, the weak cold air with a lower northerly wind speed may instead increase the pollutant concentration due to the transport of pollutants.
In this paper, the correlation between air pollution and meteorological elements and the configuration of high- and low-altitude weather systems in Jinan City is discussed, a synoptic conceptual model of Jinan air pollution is formed, and the effects of cold air processes of different intensities on the generation and elimination of air pollutants in Jinan City are studied. The results show that during 2016-2018 more than 75% of PM2.5 pollution episodes in Jinan City occurred in the surface uniform pressure field. If the occurrence probability of each weather pattern was equal, the surface weather pattern with the highest occurrence probability of pollution episodes was the inverted trough pattern (>55%), followed by the uniform pressure field pattern (26.8%). Moreover, there was a more than 25% occurrence probability of PM2.5 pollution when the 500 hPa circulation was controlled by such weather systems, i.e., the ridge, straight westerlies, anticyclone, behind the trough and in front of the trough. The circulation configuration at upper and lower levels with the greatest probability of PM2.5 pollution (>50%) in Jinan City was the type of the surface inverted trough and behind the upper-level trough, followed by the type of the surface inverted trough and the upper-level straight westerlies, and the type of the surface uniform pressure field and behind the upper-level trough. For the average, the mixed layer height was below 1000 m during PM2.5 pollution episodes and was less than 800 m under heavy pollution. During pollution periods, the average relative humidity is 65%±20%, and the average temperature was 6℃±1℃. The effect of cold air with different intensities on the pollutant episodes was complex. The stronger cold air (ΔT24 h>4.3℃, Δp24 h>4.74 hPa) with a certain duration, such as the northerly wind greater than 3.5 m·s-1 lasting more than 9.6 h, can remove pollutants completely. The slightly weaker cold air may be beneficial to reduce pollutant concentration. However, the weak cold air with a lower northerly wind speed may instead increase the pollutant concentration due to the transport of pollutants.
2022, 48(10):1292-1302.
DOI: 10.7519/j.issn.1000-0526.2022.050502
Abstract:
In this study, based on the methods for object-based vertification and neighborhood, the hourly precipitation data from the CMADaas （China Meteorological Administration Data as a server）, the forecast performances of three numerical models during the main flood seasons from 2019 to 2020 in Liaoning Province are investigated. The three models are the Shanghai Numerical Prediction Model of China Meteorological Administration (CMA-SH9), the Mesoscale Weather Numerical Prediction System of China Meteorological Administration (CMA-MESO) and the Rapid-Refresh Multi-Scale Analysis and Prediction System-Northeast China Model of China Meteorological Administration (CMA-DB). The results show that even for the kilometer-scale or near-kilometer-scale models, there are still obvious deviations in the forecast of the heavy rainfall area (12 h cumulative rainfall ≥ 50 mm) within the 36 h lead time. The ratio of overlapping area between the forecasted and observed heavy rainfall areas is generally less than 10% of the total area, and in individual cases the value is close to 20%, such as the forecast of CMA-MESO on cyclone-type precipitation processes. The deviation of rainfall area results in a high missing alarm rate (MAR) (generally around 75%, and the MAR of the CMA-MESO is 10%-20% lower than that). The MAR of heavy precipitation forecast for the rear of high-pressure type precipitation exceeds 80%. Besides, the deviation of heavy rainfall area also results in a higher false alarm rate (FAR). For the forecast of short-term heavy rainfall (1 h rainfall ≥ 20 mm), by analyzing the mean values of the statistical indexes within 12 h forecast lead time, we find that the average percentage of detection is below 10%, with the maximum value being only 9.2%. The average FAR is 58.7%. Among the three types of rainfall processes, the model has the poorest performance in the forecast of short-term heavy rainfall in typhoon-type rainfall processes.
In this study, based on the methods for object-based vertification and neighborhood, the hourly precipitation data from the CMADaas （China Meteorological Administration Data as a server）, the forecast performances of three numerical models during the main flood seasons from 2019 to 2020 in Liaoning Province are investigated. The three models are the Shanghai Numerical Prediction Model of China Meteorological Administration (CMA-SH9), the Mesoscale Weather Numerical Prediction System of China Meteorological Administration (CMA-MESO) and the Rapid-Refresh Multi-Scale Analysis and Prediction System-Northeast China Model of China Meteorological Administration (CMA-DB). The results show that even for the kilometer-scale or near-kilometer-scale models, there are still obvious deviations in the forecast of the heavy rainfall area (12 h cumulative rainfall ≥ 50 mm) within the 36 h lead time. The ratio of overlapping area between the forecasted and observed heavy rainfall areas is generally less than 10% of the total area, and in individual cases the value is close to 20%, such as the forecast of CMA-MESO on cyclone-type precipitation processes. The deviation of rainfall area results in a high missing alarm rate (MAR) (generally around 75%, and the MAR of the CMA-MESO is 10%-20% lower than that). The MAR of heavy precipitation forecast for the rear of high-pressure type precipitation exceeds 80%. Besides, the deviation of heavy rainfall area also results in a higher false alarm rate (FAR). For the forecast of short-term heavy rainfall (1 h rainfall ≥ 20 mm), by analyzing the mean values of the statistical indexes within 12 h forecast lead time, we find that the average percentage of detection is below 10%, with the maximum value being only 9.2%. The average FAR is 58.7%. Among the three types of rainfall processes, the model has the poorest performance in the forecast of short-term heavy rainfall in typhoon-type rainfall processes.
2022, 48(10):1303-1311.
DOI: 10.7519/j.issn.1000-0526.2022.062001
Abstract:
In this paper, we set a full irrigation test for winter wheat at different growth stages from the getting-up to the grain filling, that is, the full irrigating treatment is carried out in the getting-up stage (T1), the getting-up and jointing stages (T2), and the earing-up and grain filling stages (T3), respectively. The whole process from soil water saturation to drought in natural state is simulated, and the effects of persistent water stress on photosynthesis and yield of winter wheat are studied by taking full irrigating treatment at each growth stage from the getting-up to the filling stages as a control (CK）, so as to provide a reference for selecting a good irrigation timing in the spring farmland of winter wheat. The results show that the chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci) of flag leaves of wheat all decrease under persistent water stress, and the diurnal variation peak of photosynthesis appears earlier to different extents. At the three stages of T1, T2 and T3, the Tr and Ci of wheat treated by sufficient irrigation at T1, T2 and T3 are significantly different from those of CK at different growing stages, but there is no significant difference between the treatments of T1, T2 and T3 at the mid-filling stage. The chlorophyll content, Pn and Gs are reduced more significantly in the treatment of SPAD at the grain-filling than in the treatment of continuous water stress only at T2, even after the treatment of continuous water stress at T3. Winter wheat is subjected to persistent water stress at T3, which could result in the most obvious decrease in spike number and grain number per spike, and has the greatest effect on the yield of winter wheat.
In this paper, we set a full irrigation test for winter wheat at different growth stages from the getting-up to the grain filling, that is, the full irrigating treatment is carried out in the getting-up stage (T1), the getting-up and jointing stages (T2), and the earing-up and grain filling stages (T3), respectively. The whole process from soil water saturation to drought in natural state is simulated, and the effects of persistent water stress on photosynthesis and yield of winter wheat are studied by taking full irrigating treatment at each growth stage from the getting-up to the filling stages as a control (CK）, so as to provide a reference for selecting a good irrigation timing in the spring farmland of winter wheat. The results show that the chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci) of flag leaves of wheat all decrease under persistent water stress, and the diurnal variation peak of photosynthesis appears earlier to different extents. At the three stages of T1, T2 and T3, the Tr and Ci of wheat treated by sufficient irrigation at T1, T2 and T3 are significantly different from those of CK at different growing stages, but there is no significant difference between the treatments of T1, T2 and T3 at the mid-filling stage. The chlorophyll content, Pn and Gs are reduced more significantly in the treatment of SPAD at the grain-filling than in the treatment of continuous water stress only at T2, even after the treatment of continuous water stress at T3. Winter wheat is subjected to persistent water stress at T3, which could result in the most obvious decrease in spike number and grain number per spike, and has the greatest effect on the yield of winter wheat.
2022, 48(10):1312-1320.
DOI: 10.7519/j.issn.1000-0526.2022.080501
Abstract:
Based on monthly precipitation data of three meteorological stations in the eastern pamirs during the past 58 years (1961-2018), this paper uses innovative trend analysis (ITA), Mann-Kendall (M-K) nonparametric test and Sen’s slope estimation method to analyze the variation trend of precipitation in the eastern Pamirs. The results show that the results obtained by the three methods are highly consistent. In recent years, the precipitation in the eastern pamirs has an increasing trend. According to Sen’s slope estimation method, 69.44% shows an increasing trend of precipitation, and 11.11% shows a decreasing trend. The precipitation increases in 75% of the months and decreases in 22.22% of the months by M-K method. According to ITA analysis, precipitation increases in 94.44% of the months and decreases in 5.56% of the months. However, there are also differences among the three methods in the analysis process. For example, the most obvious difference is that the β value of Tashkogan meteorological station in five months by using Sen’s slope estimation method is 0, indicating no trend of change, which is significantly different from the results of the other two methods. ITA and M-K methods can distinguish the trend of time series more accurately, and are almost not affected by outliers. In addition, ITA method has the strongest significance trend, followed by M-K method, and Sen’s slope estimation performance is relatively general. The ITA analysis has passed the 0.10 significance level test in 〖JP2〗63.89% of the months and M-K has passed the 0.10 significance level test in 25% of the months. Compared with the traditional analysis method, ITA has the advantage that it can give the range and trend of increase or decrease of different levels of precipitation in different months. Therefore, ITA can effectively identify the hidden micro trend that cannot be determined by the traditional test, and is more helpful to analyze the change trend of hydrometeorological data series.〖JP〗
Based on monthly precipitation data of three meteorological stations in the eastern pamirs during the past 58 years (1961-2018), this paper uses innovative trend analysis (ITA), Mann-Kendall (M-K) nonparametric test and Sen’s slope estimation method to analyze the variation trend of precipitation in the eastern Pamirs. The results show that the results obtained by the three methods are highly consistent. In recent years, the precipitation in the eastern pamirs has an increasing trend. According to Sen’s slope estimation method, 69.44% shows an increasing trend of precipitation, and 11.11% shows a decreasing trend. The precipitation increases in 75% of the months and decreases in 22.22% of the months by M-K method. According to ITA analysis, precipitation increases in 94.44% of the months and decreases in 5.56% of the months. However, there are also differences among the three methods in the analysis process. For example, the most obvious difference is that the β value of Tashkogan meteorological station in five months by using Sen’s slope estimation method is 0, indicating no trend of change, which is significantly different from the results of the other two methods. ITA and M-K methods can distinguish the trend of time series more accurately, and are almost not affected by outliers. In addition, ITA method has the strongest significance trend, followed by M-K method, and Sen’s slope estimation performance is relatively general. The ITA analysis has passed the 0.10 significance level test in 〖JP2〗63.89% of the months and M-K has passed the 0.10 significance level test in 25% of the months. Compared with the traditional analysis method, ITA has the advantage that it can give the range and trend of increase or decrease of different levels of precipitation in different months. Therefore, ITA can effectively identify the hidden micro trend that cannot be determined by the traditional test, and is more helpful to analyze the change trend of hydrometeorological data series.〖JP〗
DI Jingyue
,
XU Fengwen
,
LI Huanlian
,
LI Yumei
,
ZHANG Guoping
,
CHEN Chunli
,
FANG Zhiwei
,
BAO Hongjun
2022, 48(10):1321-1332.
DOI: 10.7519/j.issn.1000-0526.2022.072202
Abstract:
Geological hazards such as landslides and debris flows are usually caused by severe precipitation directly, so analyzing the correlation between geological hazards and severe precipitation is of great significance. In this paper, four continuous severe rainfall processes in July 2020 responsible for geological disaster events in Enshi Autonomous Prefecture, southwestern Hubei Province are analyzed, the relationships between rainfall intensity and duration are investigated, and the geological disasters and the disaster-caused background in recent years are compared. Based on the potential dangerous 〖JP2〗degree and regional vulnerability 〖JP〗degree of geological disasters and combined with multi-source quantitative precipitation estimation (QPE) with 5 km spatial resolution and 24 h temporal resolution, the land-surface hydrological model is driven to simulate the runoff and soil moisture characteristics during the disaster process. The causes of cluster-occurring geological disasters induced by the fourth rainfall process from 15 to 19 July are emphatically analyzed. The results reveal that most areas of Enshi Autonomous Prefecture are of high potential dangerous degree but have low degree of vulnerability. The rainfall processes with accumulated precipitation over 100 mm, daily accumulated rainfall over 50 mm, or hourly rainfall with 10-30 mm can possibly trigger geological disasters in this region. The land-surface hydrological simulation can better represent the occurrence and development of disasters, while the I-D curve established in this paper can be used as an indicator for early warning in the concerned area.
Geological hazards such as landslides and debris flows are usually caused by severe precipitation directly, so analyzing the correlation between geological hazards and severe precipitation is of great significance. In this paper, four continuous severe rainfall processes in July 2020 responsible for geological disaster events in Enshi Autonomous Prefecture, southwestern Hubei Province are analyzed, the relationships between rainfall intensity and duration are investigated, and the geological disasters and the disaster-caused background in recent years are compared. Based on the potential dangerous 〖JP2〗degree and regional vulnerability 〖JP〗degree of geological disasters and combined with multi-source quantitative precipitation estimation (QPE) with 5 km spatial resolution and 24 h temporal resolution, the land-surface hydrological model is driven to simulate the runoff and soil moisture characteristics during the disaster process. The causes of cluster-occurring geological disasters induced by the fourth rainfall process from 15 to 19 July are emphatically analyzed. The results reveal that most areas of Enshi Autonomous Prefecture are of high potential dangerous degree but have low degree of vulnerability. The rainfall processes with accumulated precipitation over 100 mm, daily accumulated rainfall over 50 mm, or hourly rainfall with 10-30 mm can possibly trigger geological disasters in this region. The land-surface hydrological simulation can better represent the occurrence and development of disasters, while the I-D curve established in this paper can be used as an indicator for early warning in the concerned area.
2022, 48(10):1333-1342.
DOI: 10.7519/j.issn.1000-0526.2022.070102
Abstract:
Based on the observation data of the daily average temperature in Changsha from 1961 to 2020 and the development period of double cropping rice from 1996 to 2020, through the comparative analysis of the applicability of different statistical methods and different boundary temperatures, this paper optimizes the research method of safe growth period of double cropping indica rice and applies it to the longterm study of safe growth period of double cropping rice in Changsha. The results show that the continuous statistical method is adopted for the boundary temperature statistics. The air temperature of 8℃ is used as the sowing boundary temperature of early rice, and 22℃ as the full panicle boundary temperature of late rice. The number of days from the first day of 3 consecutive days when the air temperature ≥8℃ to the last day of 3 consecutive days when the air temperature ≥22℃ is used as the safe growth period of double cropping rice. These indices are suitable for the study on the safe growth period of double cropping rice in Changsha or other double cropping indica rice areas covered with plastic film. In Changsha Area, 80% of the guarantee rate ≥8℃ is on 21 March, and the sowing date with boundary temperature ≥8℃ is significantly ahead of schedule; the date of 80% guarantee rate of safe full heading of late rice is 9 September, and the safe full heading date is delayed but not obvious. The safe growth rate of double cropping rice is 80%, the number of days exceeded 179 d, and the safe growth period is prolonged significantly.
Based on the observation data of the daily average temperature in Changsha from 1961 to 2020 and the development period of double cropping rice from 1996 to 2020, through the comparative analysis of the applicability of different statistical methods and different boundary temperatures, this paper optimizes the research method of safe growth period of double cropping indica rice and applies it to the longterm study of safe growth period of double cropping rice in Changsha. The results show that the continuous statistical method is adopted for the boundary temperature statistics. The air temperature of 8℃ is used as the sowing boundary temperature of early rice, and 22℃ as the full panicle boundary temperature of late rice. The number of days from the first day of 3 consecutive days when the air temperature ≥8℃ to the last day of 3 consecutive days when the air temperature ≥22℃ is used as the safe growth period of double cropping rice. These indices are suitable for the study on the safe growth period of double cropping rice in Changsha or other double cropping indica rice areas covered with plastic film. In Changsha Area, 80% of the guarantee rate ≥8℃ is on 21 March, and the sowing date with boundary temperature ≥8℃ is significantly ahead of schedule; the date of 80% guarantee rate of safe full heading of late rice is 9 September, and the safe full heading date is delayed but not obvious. The safe growth rate of double cropping rice is 80%, the number of days exceeded 179 d, and the safe growth period is prolonged significantly.
2022, 48(10):1343-1353.
DOI: 10.7519/j.issn.1000-0526.2022.090401
Abstract:
Based on the meteorological observation data, NCEP/NCAR atmospheric reanalysis data and NOAA SST data, this paper analyzes the main climate characteristics and discusses the cause diagnosis in China in the spring of 2022 by using correlation and synthesis analysis methods. The results show that in spring 2022 (March-April-May, MAM), the process of monsoon rain belt in China is earlier generally. China experienced the warmest spring since 1961, with an average temperature reaching 12.1℃. The MAM precipitation averaged (154 mm) in China was close to normal, but the precipitation reached unprece-dentedly high values in Southwest China, showing distinguished spatial diversity. A northwest-southeast anomalous circulation pattern “―＋―” was formed in the middle-upper troposphere, which started from the north of Ural Mountains, via the Tibetan Plateau, and to the Indo-China Peninsula. Such pattern allowed the low-latitude anomalous easterly airflow to converge with southward northeast-northerly airflow in Southwest China, which further facilitated water vapor transport and intersection of cold and warm air, finally causing abnormally more precipitation in Southwest China in spring 2022. In addition, the La Ni〖AKn~D〗a event (autumn 2021 begins) acted as an important forcing factor for excessive spring precipitation in Southwest China. The sustained development of the La Ni〖AKn~D〗a in spring 2022 led to more typically anomalous circulation patterns than normal development, exacerbating the excessive precipitation in Southwest China.
Based on the meteorological observation data, NCEP/NCAR atmospheric reanalysis data and NOAA SST data, this paper analyzes the main climate characteristics and discusses the cause diagnosis in China in the spring of 2022 by using correlation and synthesis analysis methods. The results show that in spring 2022 (March-April-May, MAM), the process of monsoon rain belt in China is earlier generally. China experienced the warmest spring since 1961, with an average temperature reaching 12.1℃. The MAM precipitation averaged (154 mm) in China was close to normal, but the precipitation reached unprece-dentedly high values in Southwest China, showing distinguished spatial diversity. A northwest-southeast anomalous circulation pattern “―＋―” was formed in the middle-upper troposphere, which started from the north of Ural Mountains, via the Tibetan Plateau, and to the Indo-China Peninsula. Such pattern allowed the low-latitude anomalous easterly airflow to converge with southward northeast-northerly airflow in Southwest China, which further facilitated water vapor transport and intersection of cold and warm air, finally causing abnormally more precipitation in Southwest China in spring 2022. In addition, the La Ni〖AKn~D〗a event (autumn 2021 begins) acted as an important forcing factor for excessive spring precipitation in Southwest China. The sustained development of the La Ni〖AKn~D〗a in spring 2022 led to more typically anomalous circulation patterns than normal development, exacerbating the excessive precipitation in Southwest China.
2022, 48(10):1354-1360.
DOI: 10.7519/j.issn.1000-0526.2022.090701
Abstract:
The main characteristics of the general atmospheric circulation in July 2022 are that the polar vortex in the Northern Hemisphere was unipolar and slightly stronger than normal, the circulation in the mid-high latitude had a 4-wave pattern, and the western Pacific subtropical high was located more northern and western than normal. In July, the national average precipitation was 96.6 mm, 21% lower than normal, ranking the second lowest in the same period since 1961. The national average temperature was 23.2℃, 1.0℃ higher than normal, ranking the second highest in the same period in history since 1961. There were 6 regional heavy rain events in the month. The 1-7 July heavy precipitation process, which was triggered by typhoon landing as well as the interaction of the weakened low-pressure circulation and the westerly belt system, affected most of the central and eastern parts of China, and then the remaining 5 heavy precipitation events mainly affected the eastern part of the Northwest China, North China, Huanghuai Region and Northeast China. There were 3 typhoons born in July in total, which was less than normal. In July, there were two high-temperature weather processes, showing the characteristics of significant extreme, wide influence and long duration. Some parts of Sichuan Basin, Jiangnan Region, the eastern part of Northwest China, and Xinjiang experienced high-temperature weather above 40℃ with daily maximum temperature at many sites exceeding the historical extreme value for the same period.
The main characteristics of the general atmospheric circulation in July 2022 are that the polar vortex in the Northern Hemisphere was unipolar and slightly stronger than normal, the circulation in the mid-high latitude had a 4-wave pattern, and the western Pacific subtropical high was located more northern and western than normal. In July, the national average precipitation was 96.6 mm, 21% lower than normal, ranking the second lowest in the same period since 1961. The national average temperature was 23.2℃, 1.0℃ higher than normal, ranking the second highest in the same period in history since 1961. There were 6 regional heavy rain events in the month. The 1-7 July heavy precipitation process, which was triggered by typhoon landing as well as the interaction of the weakened low-pressure circulation and the westerly belt system, affected most of the central and eastern parts of China, and then the remaining 5 heavy precipitation events mainly affected the eastern part of the Northwest China, North China, Huanghuai Region and Northeast China. There were 3 typhoons born in July in total, which was less than normal. In July, there were two high-temperature weather processes, showing the characteristics of significant extreme, wide influence and long duration. Some parts of Sichuan Basin, Jiangnan Region, the eastern part of Northwest China, and Xinjiang experienced high-temperature weather above 40℃ with daily maximum temperature at many sites exceeding the historical extreme value for the same period.
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ISSN:1000-0526 CN:11-2282/P