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AbstractThe low temperature process of cold dew wind (from September 19 to 27 in 2011) for late rice production was dynamically monitored by using CLDAS temperature, combined with the background information of rice cultivation from multisource satellite database together with an reference to the monitoring indexes of cold dew wind disaster to verify the precision of CLDAS data, so as to provide a reference for monitoring chilling damage caused by cold dew wind in late rice production in Guangxi. The results showed that the cold wind dew caused heavy damage to an area of 3 159.76 km2, moderate damage to an area of 559.77 km2 and light damage to an area of 2 452.14 km2. The correlation coefficients between CLDAS inversion temperature and actual temperature of 12 verification meteorological stations were all larger than 0.93, and the difference in daily average temperature was 0.3 ℃. The time difference between maximum and minimum temperature provided by CLDAS and corresponding actual temperature from 12 meteorological stations was less than 1 h. The temperature data provided by CLDAS was in accordance with actual temperature data. With an advantage of rapidly, minutely and accurately monitoring the grade distribution of local cold dew wind disaster for late rice, CLDAS can be used in monitoring cold dew wind in late rice production in Guangxi.
Key wordsCold dew wind; Late rice; CLDAS; Remote sensing; Guangxi
Received: September 20, 2018Accepted: January 5, 2019
Supported by the National Agricultural Science and Technology Achievements Transformation Project of China (2014GB2E100281); the Science and Technology Key R&D Program of Guangxi (Guike AB17195037).
Yanli CHEN (1982-), female, P. R. China, senor engineer, master, devoted to research about agricultural remote sensing application, associate researcher, devoted to research about pear cultivation and breeding, Email: cyl0505@sina.com.
* Corresponding author. Yan HE (1967-), female, P. R. China, senor engineer, demoted to research about agricultural meteorological monitoring, early warning and assessment, Email: heyan_gx@163.com.
Cold dew wind is a kind of lowtemperature cold damage caused by the cold air intrusion in autumn, which can bring about obvious decrease in temperature, thereby reducing rice production. It is also one of the main disaster factors in the growth period of southern late rice. Guangxi belongs to the subtropical monsoon climate zone with abundant climatic resources and suitable for rice growth. It is one of the main producing areas of doubleseason rice in China. However, under the influence of complex geographical topography and monsoons in Guangxi, the period before and after the Cold Dew in autumn is the key period for the heading and flowering of late rice, when the daily average temperature falling below 22 ℃ for 2 or more consecutive days can result in vacant shells, unfilled grains and even yield reduction of late rice. The temperature reduction is generally accompanied by northerly winds, commonly known as cold dew wind, and cold dew wind is related to cold air activity. When the north strong cold air goes south and the cold air stays in the south for a long time, it is most likely to cause cold dew wind (low temperature cold damage) disasters. This meteorological disaster weather has become one of the main factors restricting the high and stable yield of late rice in Guangxi［1］, and there is still no effective preventive measure for this disaster. Therefore, the study on the monitoring and early warning technologies for cold dew wind and low temperature cold damage to rice is of important significance to ensure food safety production in southern China. At present, low temperature chilling damage monitoring mainly includes singlepoint simulation test, remote sensing technology and GIS technology［1］. Among them, the singlepoint simulation test has been carried out on rice［2-4］ and corn［5-7］, but the results have certain differences from the actual conditions due to the small sample size, the large number of climate indicators and the interactions between various factors. Remote sensing technology monitors the cold damage through the inversion of vegetation index and land surface temperature. Many scholars have used the normalized index of remote sensing inversion to monitor cotton cold damage［8］, corn and wheat frost［9-10］, and the accuracy of low temperature change by inversion of surface temperature is high with the error generally less than 1 ℃［11-13］. However, the influence of cloudy and rainy weather makes it easy to cause remote sensing data missing, and it is hard to ensure the integrity of the time series data, which has become the biggest obstacle to the application of remote sensing technology. Because the temperature has a good correlation with the geographical factors such as longitude, latitude and altitude, GIS technology can be used to effectively monitor the occurrence and extent of cold damage in certain areas［14-16］. Zhang［17］ found that it could not meet the needs of practical application by using a single means to monitor low temperature cold damage, and it had become a new trend of combining the traditional method with the new technologies to monitor low temperature cold damage. China Meteorological Administration Land Data Assimilation System (CLDAS) is the only realtime operational system in the field of land surface data assimilation in China, which provides spacetime continuous atmospheric driving data like temperature, precipitation and radiation with high spatial resolution. The monitoring results in multiple regions show that it has high accuracy［18-19］, but it is rarely seen in the application of rice cold damage monitoring. Therefore, in this paper, the temperature change data of CLDAS was used, combined with the background information of remote sensing late rice planting, to monitor the typical cold dew wind weather process in Guangxi to verify the accuracy of CLDAS data, with the aim to provide references for the late rice production in Guangxi and the accurate monitoring as well as early warning and forecasting of cold dew wind low temperature cold damage weather. Materials and Methods
Data source
The background data of late rice planting in Guangxi in 2011 was provided by the Guaqngxi Institute of Meteorological Disaster Mitigation; CLDAS temperature data was provided by the National Meteorological Information Center of China; the local singlepoint temperature observation data of Guangxi was provided by the Meteorological Information Center of Guangxi Zhuang Autonomous Region.
Method
Selection of time and indicatorsSince daily average temperature is the main climate indicator affecting the normal heading, flowering and grouting of late rice, the time phase of September 19-27 was selected for obvious characteristics of cold dew wind weather of late rice in Guangxi to perform the evaluation of the accuracy of the daily average temperature data extracted by the CLDAS.
Data storage and image processingCLDAS data product covered the region of 0°-65° N, 60°-160° E in Asia, and the time resolution was 1 h with the spatial resolution of 0.062 5°×0.062 5°. With ECMWF as the background of temperature products, data storage and image processing were completed using ENVI 5.0 with the integration of multigrid 3dimensional variation technology with the observation data from the ground automatic meteorological stations.
Spatial distribution map plottingBased on the CLDAS temperature data, the spatial distribution map of daily average temperature ≤ 22.0 ℃ was plotted according to the monitoring index of late rice cold dew disaster, and CLDAS could monitor the regional temperature change on a hourbyhour, daybyday basis.
Cold dew wind disaster grade distribution map plottingThe duration of temperature ≤ 22.0 ℃ was summarized during the cold dew wind process from September 19 to 27, 2011 by using the CLDAS daybyday temperature spatial monitoring results. The grade distribution map of cold dew wind disaster for late rice was plotted by referring to the observed daily average temperature of cold dew wind disaster for late rice, combined with the background information of remote sensing rice planting in Guangxi［20-21］.
CLDAS temperature data accuracy verificationThe accuracy of CLDAS temperature data was verified with the coefficients and the differences of the hourbyhour temperature data from 12 meteorological stations on September 21, 2011 as the indicators, and scatter diagrams were made to directly reflect the accuracy.
Classification standard of cold dew wind disaster for late rice Due to the southward movement of strong cold air from the north, the temperature in Guangxi tends to decrease before and after the Cold Dew in September and October every year. If the temperature falls to a certain critical value, it can affect the normal heading, flowering and grouting of late rice, which can increase the empty shells and unfilled grins, finally resulting in yield reduction. Such phenomenon is commonly known as the cold dew wind weather, which is also a kind of disastrous weather. The cold dew wind weather for late rice is mainly monitored using daily average temperature as the indicator, which is also used as the standard to classify the disaster grades of cold dew wind weather (Table 1).
Table 1Classification standard of cold dew wind disaster for late rice production in Guangxi
VarietyDaily average temperature∥℃
Duration of disaster grade∥d
Light Moderate Heavy
Hybrid rice≤223-56-7≥8
Indica rice≤213-56-7≥8
Japonica rice≤ 203-56-7≥8
Results and Analysis
Cold dew wind disaster situation
Affected by strong cold air, multiple cities and counties in northern Guangxi suffered the severe cold dew wind weather disasters from September 19 to 27, 2011. As shown in Fig. 1, the temperature began to decrease throughout Guangxi from September 19, and the regions with temperature ≤ 22.0 ℃ enlarged from northeast to southwest on September 20. The temperature rose in some of the southern regions on September 21, and most regions in northern Guangxi had the temperature back to normal on September 25. On September 26, the temperature dropped to below 22.0 ℃ again in most areas of Guilin, Liuzhou, Laibin, Nanning and Chongzuo. On September 27, most regions in Guangxi had the temperature back to normal except counties of Napo, Jingxi and Lingyun.
Cold dew wind disaster grade distribution and area
As shown in Fig. 2, the total disasterstricken area of late rice was 3 159.76 km2 in the process of cold dew wind weather in Guangxi from September 19 to 27, 2011. The heavystricken area was 147.85 km2, mainly in Quanzhou County (102.75 km2), Lingui County (18.09 km2) and Guanyang County (11.55 km2); the moderatestricken area was 559.77 km2, and the affected area of Quanzhou County was the largest (221.78 km2), followed by Lingui County (64.98 km2); the lightstricken area was 2 452.14 km2, and the stricken area in Laibin County was over 200 km2, while the total stricken area exceeded 100 km2 in Shanglin County and Binyang County, Liucheng County, Luzhai County, Heping City and Hele County.
Fig. 1Spatial distribution of daily average temperature ≤22 ℃ in Guangxi from September 19 to 27 in 2011
Agricultural Biotechnology2019
Accuracy of temperature data provided by CLDAS
As shown in Fig. 3, the verification results showed that the CLDAS inversion temperature data had high accuracy, and the correlation coefficient with the actual temperature data from each station was greater than 0.93 with the difference value of -0.1, average difference of 0.3 ℃. However, the occurrence time of CLDAS maximum temperature and minimum temperature was different from the actual temperature data of some stations, some advanced and some postponed, but the time difference was less than 1 h, indicating that CLDAS monitoring temperature data had high accuracy.
Application verification
In October 2016, some areas in northcentral Guangxi were affected by cold air and exposed to cold dew wind weather. From October 2 to 21, the cold dew wind weather lasted for 3 to 20 d in various regions, and heavy cold dew wind weather conditions lasted over 7 d in the counties (cities) like Ziyuan, Quanzhou, Guanyang, Xingan, Nandan, Leye, Xilin, Longlin and Jinxiu of Guangxi (Fig. 4). The actually monitored temperature data was consistent with the temperature data variation provided by CLDAS. In addition to high accuracy, the temperature data provided by CLDAS also had the advantage of fast and detailed understanding of the
Fig. 2Grade distribution of cold dew wind disaster for late rice in Guangxi from September 19 to 27 in 2011
grade distribution of cold dew wind for late rice production, providing bases and early warning scheme for monitoring the effects of
Fig. 3Scatter diagram of correlation coefficients between CLDAS inversion temperature and actual temperature in different meteorological stations in Guangxi
cold dew wind low temperature cold damage on the local late rice production in Guangxi. Therefore, CLDAS could be used for cold dew wind weather monitoring of late rice production in Guangxi.
Fig. 4Grade distribution of cold dew wind for late rice production in Guangxi from October 2 to 21 in 2016
Conclusion and Discussion
The low temperature process of cold dew wind from September 19 to 27, 2011 for late rice production was dynamically monitored by using CLDAS temperature, combined with the background information of rice cultivation from multisource satellite database together with an reference to the monitoring indexes of cold dew wind disaster. The results showed the cold wind dew caused heavy damage to an area of 3 159.76 km2, moderate damage to an area of 559.77 km2 and light damage to an area of 2 452.14 km2. The correlation coefficients between CLDAS inversion temperature and actual temperature of 12 verification meteorological stations were all larger than 0.93, and the difference in daily average temperature was 0.3 ℃ with the difference ranging from -0.1-0.8 ℃. The time difference between maximum and minimum temperature provided by CLDAS and corresponding actual temperature from 12 meteorological stations was less than 1 h. The temperature data provided by CLDAS was in accordance with actual temperature data. With an advantage of rapidly, minutely and accurately monitoring the grade distribution of local cold dew wind disaster for late rice, CLDAS can be used in monitoring cold dew wind in late rice production in Guangxi. References
［1］ HE Y, LI Z, XU SH, et al. Application of GIS in monitoring and early warning of cold damage to rice in Guangxi［J］. Journal of Catastrophology, 2012, 27(1): 68-72.
［2］ LI DM, YU XM, WANG HC. Study on some mechanism and identification of chilling injury in rice at flowering stage［J］. Scientia Agricultura Sinica, 1986, 19(2): 12-17.
［3］ HU F. The meteorological index and mechanism of chilling injury at the blooming stage of rice［J］. Scientia Agricultura Sinica, 1981, 14(2): 60-64.
［4］ GAO SH. Dynamic monitoring of delayed chilling damage in corn［J］. Journal of Natural Disasters, 2003, 12(2): 117-121.
［5］ MA SQ, WANG Q, LUO XL. Effect of climate change maize (Zea mays) growth and yield based on stage sowing［J］. Acta Ecologica Sinica, 2008, 28(5): 2131-2139.
［6］ WANG Q, MA SQ, GUO JP, et al. Effect of temperature change on maize growth rate in Northeast China［J］. Modern Agricultural Science and Technology, 2011 (7): 46-48.
［7］ LIN HR, LI ZC, ZHOU QB, et al. Monitoring forest disaster of cotton based on difference of vegetation index and canopy temperature by remote sensing［J］. Cotton Science, 2009, 21(4): 284-289.
［8］ ZHANG XY, CHEN YY, SU ZS, et al. A study on monitoring frost of main crop in the area of Ningxia by using remote sensing［J］. Remote Sensing Technology and Application, 2001, 16(1): 32-36.
［9］ ZHANG XF, CHEN HL, ZHENG YF, et al. Monitoring the freezing injury of winter wheat by remote sensing［J］. Journal of Nanjing Institute of Meteorology, 2006, 29(1): 94-100.
［10］ JI SQ, ZHANG YS, GUAN DX, et al. Remote sensing monitoring on crop chilling damage and meteorological prediction［J］. Journal of Shenyang Agricultural University, 1998 (1): 16-20.
［11］ MAO K, TANG H, CHEN Z, et al. A splitwindow algorithm for retrieving landsurface temperature from ASTER data［J］. Remote Sensing Information, 2006, 58(5): 7-11.
［12］ ZHANG JH, LI X, YAO FM, et al. The progress in retrieving land surface temperature based on thermal infrared and microwave remote sensing technologies［J］. Spectroscopy and Spectral Analysis, 2009, 29(8): 2103-2107.
［13］ GUO XL, WANG LG, QIU JJ, et al. An analysis of cold damage on rice in Northeast China based on GIS［J］. Acta Agriculturae Universitatis Jiangxiensis (Natural Science Edition), 2009, 31(3): 494-498.
［14］ HE Y, LI Z, XU SH, et al. Application of GIS in the monitoring and early warning of cold damage to rice in Guangxi［J］. Journal of Catastrophology, 2012, 27(1): 68-72. ［15］ HE Y, LI Z, ZHONG SQ, et al. The construction of cold damage models of late rice for spatial analysis and zoning in Guangxi［J］. Geographical Research, 2010 (6): 1037-1044.
［16］ TAN YJ, ZHANG JH, YAO FM, et al. Monitoring and simulation forecasting on crop chilling damage in China: research progress［J］. Chinese Journal of Ecology, 2013, 32(7): 1920-1927.
［17］ ZHANG C. CLDAS: the application in regionalization model of climate suitability index［J］. Chinese Agricultural Science Bulletin, 2017, 33(1): 120-127.
［18］ ZHANG C, WU GZ, SONG HQ, et al. Method for spatializing temperature suitability index based on CLDAS［J］. Meteorological Science and Technology, 2017, 45 (3): 555-560.
［19］ ZHONG SQ, MO JF, CHEN YL, et al. Study on rice identification technology using HJ1B data［J］. Remote Sensing Technology and Applications, 2010, 25(4): 464-468.
［20］ CHEN YL, MO WH, MO JF, et al. Objectoriented classification for the extraction of rice planting area in South China［J］. Remote Sensing Technology and Application, 2011, 26(2): 163-168.
［21］ ZHONG SQ, MO JF, MO WH, et al. Extraction and applications of remote sensing background information in Guangxi［J］. Journal of Meteorological Research and Application, 2010, 31(3): 44-49.
Key wordsCold dew wind; Late rice; CLDAS; Remote sensing; Guangxi
Received: September 20, 2018Accepted: January 5, 2019
Supported by the National Agricultural Science and Technology Achievements Transformation Project of China (2014GB2E100281); the Science and Technology Key R&D Program of Guangxi (Guike AB17195037).
Yanli CHEN (1982-), female, P. R. China, senor engineer, master, devoted to research about agricultural remote sensing application, associate researcher, devoted to research about pear cultivation and breeding, Email: cyl0505@sina.com.
* Corresponding author. Yan HE (1967-), female, P. R. China, senor engineer, demoted to research about agricultural meteorological monitoring, early warning and assessment, Email: heyan_gx@163.com.
Cold dew wind is a kind of lowtemperature cold damage caused by the cold air intrusion in autumn, which can bring about obvious decrease in temperature, thereby reducing rice production. It is also one of the main disaster factors in the growth period of southern late rice. Guangxi belongs to the subtropical monsoon climate zone with abundant climatic resources and suitable for rice growth. It is one of the main producing areas of doubleseason rice in China. However, under the influence of complex geographical topography and monsoons in Guangxi, the period before and after the Cold Dew in autumn is the key period for the heading and flowering of late rice, when the daily average temperature falling below 22 ℃ for 2 or more consecutive days can result in vacant shells, unfilled grains and even yield reduction of late rice. The temperature reduction is generally accompanied by northerly winds, commonly known as cold dew wind, and cold dew wind is related to cold air activity. When the north strong cold air goes south and the cold air stays in the south for a long time, it is most likely to cause cold dew wind (low temperature cold damage) disasters. This meteorological disaster weather has become one of the main factors restricting the high and stable yield of late rice in Guangxi［1］, and there is still no effective preventive measure for this disaster. Therefore, the study on the monitoring and early warning technologies for cold dew wind and low temperature cold damage to rice is of important significance to ensure food safety production in southern China. At present, low temperature chilling damage monitoring mainly includes singlepoint simulation test, remote sensing technology and GIS technology［1］. Among them, the singlepoint simulation test has been carried out on rice［2-4］ and corn［5-7］, but the results have certain differences from the actual conditions due to the small sample size, the large number of climate indicators and the interactions between various factors. Remote sensing technology monitors the cold damage through the inversion of vegetation index and land surface temperature. Many scholars have used the normalized index of remote sensing inversion to monitor cotton cold damage［8］, corn and wheat frost［9-10］, and the accuracy of low temperature change by inversion of surface temperature is high with the error generally less than 1 ℃［11-13］. However, the influence of cloudy and rainy weather makes it easy to cause remote sensing data missing, and it is hard to ensure the integrity of the time series data, which has become the biggest obstacle to the application of remote sensing technology. Because the temperature has a good correlation with the geographical factors such as longitude, latitude and altitude, GIS technology can be used to effectively monitor the occurrence and extent of cold damage in certain areas［14-16］. Zhang［17］ found that it could not meet the needs of practical application by using a single means to monitor low temperature cold damage, and it had become a new trend of combining the traditional method with the new technologies to monitor low temperature cold damage. China Meteorological Administration Land Data Assimilation System (CLDAS) is the only realtime operational system in the field of land surface data assimilation in China, which provides spacetime continuous atmospheric driving data like temperature, precipitation and radiation with high spatial resolution. The monitoring results in multiple regions show that it has high accuracy［18-19］, but it is rarely seen in the application of rice cold damage monitoring. Therefore, in this paper, the temperature change data of CLDAS was used, combined with the background information of remote sensing late rice planting, to monitor the typical cold dew wind weather process in Guangxi to verify the accuracy of CLDAS data, with the aim to provide references for the late rice production in Guangxi and the accurate monitoring as well as early warning and forecasting of cold dew wind low temperature cold damage weather. Materials and Methods
Data source
The background data of late rice planting in Guangxi in 2011 was provided by the Guaqngxi Institute of Meteorological Disaster Mitigation; CLDAS temperature data was provided by the National Meteorological Information Center of China; the local singlepoint temperature observation data of Guangxi was provided by the Meteorological Information Center of Guangxi Zhuang Autonomous Region.
Method
Selection of time and indicatorsSince daily average temperature is the main climate indicator affecting the normal heading, flowering and grouting of late rice, the time phase of September 19-27 was selected for obvious characteristics of cold dew wind weather of late rice in Guangxi to perform the evaluation of the accuracy of the daily average temperature data extracted by the CLDAS.
Data storage and image processingCLDAS data product covered the region of 0°-65° N, 60°-160° E in Asia, and the time resolution was 1 h with the spatial resolution of 0.062 5°×0.062 5°. With ECMWF as the background of temperature products, data storage and image processing were completed using ENVI 5.0 with the integration of multigrid 3dimensional variation technology with the observation data from the ground automatic meteorological stations.
Spatial distribution map plottingBased on the CLDAS temperature data, the spatial distribution map of daily average temperature ≤ 22.0 ℃ was plotted according to the monitoring index of late rice cold dew disaster, and CLDAS could monitor the regional temperature change on a hourbyhour, daybyday basis.
Cold dew wind disaster grade distribution map plottingThe duration of temperature ≤ 22.0 ℃ was summarized during the cold dew wind process from September 19 to 27, 2011 by using the CLDAS daybyday temperature spatial monitoring results. The grade distribution map of cold dew wind disaster for late rice was plotted by referring to the observed daily average temperature of cold dew wind disaster for late rice, combined with the background information of remote sensing rice planting in Guangxi［20-21］.
CLDAS temperature data accuracy verificationThe accuracy of CLDAS temperature data was verified with the coefficients and the differences of the hourbyhour temperature data from 12 meteorological stations on September 21, 2011 as the indicators, and scatter diagrams were made to directly reflect the accuracy.
Classification standard of cold dew wind disaster for late rice Due to the southward movement of strong cold air from the north, the temperature in Guangxi tends to decrease before and after the Cold Dew in September and October every year. If the temperature falls to a certain critical value, it can affect the normal heading, flowering and grouting of late rice, which can increase the empty shells and unfilled grins, finally resulting in yield reduction. Such phenomenon is commonly known as the cold dew wind weather, which is also a kind of disastrous weather. The cold dew wind weather for late rice is mainly monitored using daily average temperature as the indicator, which is also used as the standard to classify the disaster grades of cold dew wind weather (Table 1).
Table 1Classification standard of cold dew wind disaster for late rice production in Guangxi
VarietyDaily average temperature∥℃
Duration of disaster grade∥d
Light Moderate Heavy
Hybrid rice≤223-56-7≥8
Indica rice≤213-56-7≥8
Japonica rice≤ 203-56-7≥8
Results and Analysis
Cold dew wind disaster situation
Affected by strong cold air, multiple cities and counties in northern Guangxi suffered the severe cold dew wind weather disasters from September 19 to 27, 2011. As shown in Fig. 1, the temperature began to decrease throughout Guangxi from September 19, and the regions with temperature ≤ 22.0 ℃ enlarged from northeast to southwest on September 20. The temperature rose in some of the southern regions on September 21, and most regions in northern Guangxi had the temperature back to normal on September 25. On September 26, the temperature dropped to below 22.0 ℃ again in most areas of Guilin, Liuzhou, Laibin, Nanning and Chongzuo. On September 27, most regions in Guangxi had the temperature back to normal except counties of Napo, Jingxi and Lingyun.
Cold dew wind disaster grade distribution and area
As shown in Fig. 2, the total disasterstricken area of late rice was 3 159.76 km2 in the process of cold dew wind weather in Guangxi from September 19 to 27, 2011. The heavystricken area was 147.85 km2, mainly in Quanzhou County (102.75 km2), Lingui County (18.09 km2) and Guanyang County (11.55 km2); the moderatestricken area was 559.77 km2, and the affected area of Quanzhou County was the largest (221.78 km2), followed by Lingui County (64.98 km2); the lightstricken area was 2 452.14 km2, and the stricken area in Laibin County was over 200 km2, while the total stricken area exceeded 100 km2 in Shanglin County and Binyang County, Liucheng County, Luzhai County, Heping City and Hele County.
Fig. 1Spatial distribution of daily average temperature ≤22 ℃ in Guangxi from September 19 to 27 in 2011
Agricultural Biotechnology2019
Accuracy of temperature data provided by CLDAS
As shown in Fig. 3, the verification results showed that the CLDAS inversion temperature data had high accuracy, and the correlation coefficient with the actual temperature data from each station was greater than 0.93 with the difference value of -0.1, average difference of 0.3 ℃. However, the occurrence time of CLDAS maximum temperature and minimum temperature was different from the actual temperature data of some stations, some advanced and some postponed, but the time difference was less than 1 h, indicating that CLDAS monitoring temperature data had high accuracy.
Application verification
In October 2016, some areas in northcentral Guangxi were affected by cold air and exposed to cold dew wind weather. From October 2 to 21, the cold dew wind weather lasted for 3 to 20 d in various regions, and heavy cold dew wind weather conditions lasted over 7 d in the counties (cities) like Ziyuan, Quanzhou, Guanyang, Xingan, Nandan, Leye, Xilin, Longlin and Jinxiu of Guangxi (Fig. 4). The actually monitored temperature data was consistent with the temperature data variation provided by CLDAS. In addition to high accuracy, the temperature data provided by CLDAS also had the advantage of fast and detailed understanding of the
Fig. 2Grade distribution of cold dew wind disaster for late rice in Guangxi from September 19 to 27 in 2011
grade distribution of cold dew wind for late rice production, providing bases and early warning scheme for monitoring the effects of
Fig. 3Scatter diagram of correlation coefficients between CLDAS inversion temperature and actual temperature in different meteorological stations in Guangxi
cold dew wind low temperature cold damage on the local late rice production in Guangxi. Therefore, CLDAS could be used for cold dew wind weather monitoring of late rice production in Guangxi.
Fig. 4Grade distribution of cold dew wind for late rice production in Guangxi from October 2 to 21 in 2016
Conclusion and Discussion
The low temperature process of cold dew wind from September 19 to 27, 2011 for late rice production was dynamically monitored by using CLDAS temperature, combined with the background information of rice cultivation from multisource satellite database together with an reference to the monitoring indexes of cold dew wind disaster. The results showed the cold wind dew caused heavy damage to an area of 3 159.76 km2, moderate damage to an area of 559.77 km2 and light damage to an area of 2 452.14 km2. The correlation coefficients between CLDAS inversion temperature and actual temperature of 12 verification meteorological stations were all larger than 0.93, and the difference in daily average temperature was 0.3 ℃ with the difference ranging from -0.1-0.8 ℃. The time difference between maximum and minimum temperature provided by CLDAS and corresponding actual temperature from 12 meteorological stations was less than 1 h. The temperature data provided by CLDAS was in accordance with actual temperature data. With an advantage of rapidly, minutely and accurately monitoring the grade distribution of local cold dew wind disaster for late rice, CLDAS can be used in monitoring cold dew wind in late rice production in Guangxi. References
［1］ HE Y, LI Z, XU SH, et al. Application of GIS in monitoring and early warning of cold damage to rice in Guangxi［J］. Journal of Catastrophology, 2012, 27(1): 68-72.
［2］ LI DM, YU XM, WANG HC. Study on some mechanism and identification of chilling injury in rice at flowering stage［J］. Scientia Agricultura Sinica, 1986, 19(2): 12-17.
［3］ HU F. The meteorological index and mechanism of chilling injury at the blooming stage of rice［J］. Scientia Agricultura Sinica, 1981, 14(2): 60-64.
［4］ GAO SH. Dynamic monitoring of delayed chilling damage in corn［J］. Journal of Natural Disasters, 2003, 12(2): 117-121.
［5］ MA SQ, WANG Q, LUO XL. Effect of climate change maize (Zea mays) growth and yield based on stage sowing［J］. Acta Ecologica Sinica, 2008, 28(5): 2131-2139.
［6］ WANG Q, MA SQ, GUO JP, et al. Effect of temperature change on maize growth rate in Northeast China［J］. Modern Agricultural Science and Technology, 2011 (7): 46-48.
［7］ LIN HR, LI ZC, ZHOU QB, et al. Monitoring forest disaster of cotton based on difference of vegetation index and canopy temperature by remote sensing［J］. Cotton Science, 2009, 21(4): 284-289.
［8］ ZHANG XY, CHEN YY, SU ZS, et al. A study on monitoring frost of main crop in the area of Ningxia by using remote sensing［J］. Remote Sensing Technology and Application, 2001, 16(1): 32-36.
［9］ ZHANG XF, CHEN HL, ZHENG YF, et al. Monitoring the freezing injury of winter wheat by remote sensing［J］. Journal of Nanjing Institute of Meteorology, 2006, 29(1): 94-100.
［10］ JI SQ, ZHANG YS, GUAN DX, et al. Remote sensing monitoring on crop chilling damage and meteorological prediction［J］. Journal of Shenyang Agricultural University, 1998 (1): 16-20.
［11］ MAO K, TANG H, CHEN Z, et al. A splitwindow algorithm for retrieving landsurface temperature from ASTER data［J］. Remote Sensing Information, 2006, 58(5): 7-11.
［12］ ZHANG JH, LI X, YAO FM, et al. The progress in retrieving land surface temperature based on thermal infrared and microwave remote sensing technologies［J］. Spectroscopy and Spectral Analysis, 2009, 29(8): 2103-2107.
［13］ GUO XL, WANG LG, QIU JJ, et al. An analysis of cold damage on rice in Northeast China based on GIS［J］. Acta Agriculturae Universitatis Jiangxiensis (Natural Science Edition), 2009, 31(3): 494-498.
［14］ HE Y, LI Z, XU SH, et al. Application of GIS in the monitoring and early warning of cold damage to rice in Guangxi［J］. Journal of Catastrophology, 2012, 27(1): 68-72. ［15］ HE Y, LI Z, ZHONG SQ, et al. The construction of cold damage models of late rice for spatial analysis and zoning in Guangxi［J］. Geographical Research, 2010 (6): 1037-1044.
［16］ TAN YJ, ZHANG JH, YAO FM, et al. Monitoring and simulation forecasting on crop chilling damage in China: research progress［J］. Chinese Journal of Ecology, 2013, 32(7): 1920-1927.
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