Daily Total Column Ozone (TCO) measurements compiled from Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instruments (OMI) were used to analyze the global and hemispherical TCO interannual variations. Tw...Daily Total Column Ozone (TCO) measurements compiled from Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instruments (OMI) were used to analyze the global and hemispherical TCO interannual variations. Two periods of TCO measurements were analyzed separately covering full years. For the 1978-1994 period, the TCO showed a global decade decrease rate of 13.45 DU (about -4.3%). For the Northern Hemisphere(NH) the decade decrease rate was of 12.96 DU (-4.0%), while in the Southern Hemisphere (SH) was of 13.57 DU (-4.5%). These decreases in ozone trends, using the totality of TOMS and OMI satellite measurements, are greater than those reported in literature. The 1998-2014 period global TCO decade decrease rate was of 1.56 DU, corresponding 0.94 DU and 0.138 DU for the NH and SH, respectively. The global TCO variations must show a double annual periodicity, the first one with maxima in March due to the Northern Hemisphere (NH) and the second one during September due to the Southern Hemisphere (SH). However, the maxima due to SH TCO interannual variations have gradually vanished. A disturbance in the SH TCO interannual variations has appeared since 1980;graphically the periodicity brakes down and transforms to a double peak from 1985 and on. This effect can be attributed to the hemispheric impact of the ozone hole at the South Pole. Between October 1, 2004 and December 14, 2005 TOMS and OMI have recorded this disturbance unequivocally. We conclude that the disturbance in SH TCO has an irreversible character.展开更多
This paper uses Dobson spectrometer total ozone data,Total Ozone Mapping Spectrometer(TOMS) data and radiosonde reports from Kunming,which is located in southwest China,from 1980 to 2008 to analyze the total ozone-cli...This paper uses Dobson spectrometer total ozone data,Total Ozone Mapping Spectrometer(TOMS) data and radiosonde reports from Kunming,which is located in southwest China,from 1980 to 2008 to analyze the total ozone-climate relationship.The total ozone decadal long-term trend and abrupt change were studied using enhanced Dobson data whose missing data were amended by the TOMS data.Stepwise linear regression was used for the selection of the key factors that influence total ozone,including temperatures,geopotential heights,depressions of the dew point,wind velocities,and total solar radiation.The relationship between the selected factors and total ozone was analyzed using the methods of stepwise regression and partial least squares regression(PLSR).Results showed that although the PLSR method was slightly better and more reasonable to study the relationship than stepwise regression,while the two regression results were only slightly different.It was also suggested that local climate,especially local circulation and temperature,were important for the variations in total ozone,and the local climate could almost linearly explain 80% of the variance of total ozone.The relationship also indicated that the abrupt change of total ozone in the year 1994 may be related to abrupt local climate change.展开更多
In this paper the grid data of total ozone mapping spectrograph (TOMS) installed on Nimbus 7 satellite (1978 to 1994) was used and the spatial and temporal distribution of total ozone over China was analyzed. The res...In this paper the grid data of total ozone mapping spectrograph (TOMS) installed on Nimbus 7 satellite (1978 to 1994) was used and the spatial and temporal distribution of total ozone over China was analyzed. The research indicates that the Qinghai Tibet Plateau destroyed the latitudinal distribution of total ozone of China and the low value closed center emerged over Qinghai Tibet Plateau. Long time change trends of seasonal total ozone of Qinghai Tibet Plateau are provided. It shows that the most obvious decrease of total ozone occurs in winter (Jan.), then in summer (Jul.), the relevant slow change occurs in autumn (Oct.) and spring (Apr.).展开更多
Two statistical validation methods were used to evaluate the confidence level of the Total Column Ozone (TCO) measurements recorded by satellite systems measuring simultaneously, one using the normal distribution and ...Two statistical validation methods were used to evaluate the confidence level of the Total Column Ozone (TCO) measurements recorded by satellite systems measuring simultaneously, one using the normal distribution and another using the Mann-Whitney test. First, the reliability of the TCO measurements was studied hemispherically. While similar coincidences and levels of significance > 0.05 were found with the two statistical tests, an enormous variability in the levels of significance throughout the year was also exposed. Then, using the same statistical comparison methods, a latitudinal study was carried out in order to elucidate the geographical distribution that gave rise to this variability. Our study reveals that between the TOMS and OMI measurements in 2005 there was only a coincidence in 50% of the latitudes, which explained the variability. This implies that for 2005, the TOMS measurements are not completely reliable, except between the -50° and -15° latitude band in the southern hemisphere and between +15° and +50° latitude band in the northern hemisphere. In the case of OMI-OMPS, we observe that between 2011 and 2016 the measurements of both satellite systems are reasonably similar with a confidence level higher than 95%. However, in 2017 a band with a width of 20° latitude centered on the equator appeared, in which the significance levels were much less than 0.05, indicating that one of the measurement systems had begun to fail. In 2018, the fault was not only located in the equator, but was also replicated in various bands in the Southern Hemisphere. We interpret this as evidence of irreversible failure in one of the measurement systems.展开更多
The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI （Ozone Monitoring Instrument Aerosol Index） data during 2005-007. The...The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI （Ozone Monitoring Instrument Aerosol Index） data during 2005-007. The results show that there is a high correla- tion of At （the correlation coefficients are as high as 0.83 in March, 0.62 in April and 054 in May） between the Mongolia Gobi Desert and the west coast region of the United States （40°-50°N, 120°- 130°W）, indicating a strong source-receptor area relationship. Through calculating the lag correlation coefficient of the dust propagation time, we determined that the dust propagation lime fi＇om the Mongolia Gobi Desert to the west coast of the United States is about 6-7 days at the 99% confidence level.展开更多
Using the Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical depth （AOD） at 500 nm data from 1980 to 2001 in north China, the spatial and temporal variations of AOD were examined. Seasonal AODs in Tak...Using the Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical depth （AOD） at 500 nm data from 1980 to 2001 in north China, the spatial and temporal variations of AOD were examined. Seasonal AODs in Taklimakan Desert were 0.69 and 0.44 in spring and summer, respectively, which were mainly due to frequent occurrences of dust events in this region. Dust activities in spring also led to high aerosol loading in Gobi Desert and in northeast China where spring AODs were 0.33 and 0.29, respectively. Heavily impacted by events such as volcano eruption, forest fires and extraordinary dust storms, AODs showed large inter-annual variations. A decreasing tendency in AOD was observed in north China during 1980-1991, though a reverse tendency was revealed during 1997-2001, especially for spring AOD in northeast China. Further study is required to figure out how much human activities have contributed to the AOD tendency in north China.展开更多
文摘Daily Total Column Ozone (TCO) measurements compiled from Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instruments (OMI) were used to analyze the global and hemispherical TCO interannual variations. Two periods of TCO measurements were analyzed separately covering full years. For the 1978-1994 period, the TCO showed a global decade decrease rate of 13.45 DU (about -4.3%). For the Northern Hemisphere(NH) the decade decrease rate was of 12.96 DU (-4.0%), while in the Southern Hemisphere (SH) was of 13.57 DU (-4.5%). These decreases in ozone trends, using the totality of TOMS and OMI satellite measurements, are greater than those reported in literature. The 1998-2014 period global TCO decade decrease rate was of 1.56 DU, corresponding 0.94 DU and 0.138 DU for the NH and SH, respectively. The global TCO variations must show a double annual periodicity, the first one with maxima in March due to the Northern Hemisphere (NH) and the second one during September due to the Southern Hemisphere (SH). However, the maxima due to SH TCO interannual variations have gradually vanished. A disturbance in the SH TCO interannual variations has appeared since 1980;graphically the periodicity brakes down and transforms to a double peak from 1985 and on. This effect can be attributed to the hemispheric impact of the ozone hole at the South Pole. Between October 1, 2004 and December 14, 2005 TOMS and OMI have recorded this disturbance unequivocally. We conclude that the disturbance in SH TCO has an irreversible character.
基金supported by the National Basic Research Program of China (973 Program) under Grant 2009CB421406 the Chinese Academy of Sciences under Grant KZCX-YW-Q1-02
文摘This paper uses Dobson spectrometer total ozone data,Total Ozone Mapping Spectrometer(TOMS) data and radiosonde reports from Kunming,which is located in southwest China,from 1980 to 2008 to analyze the total ozone-climate relationship.The total ozone decadal long-term trend and abrupt change were studied using enhanced Dobson data whose missing data were amended by the TOMS data.Stepwise linear regression was used for the selection of the key factors that influence total ozone,including temperatures,geopotential heights,depressions of the dew point,wind velocities,and total solar radiation.The relationship between the selected factors and total ozone was analyzed using the methods of stepwise regression and partial least squares regression(PLSR).Results showed that although the PLSR method was slightly better and more reasonable to study the relationship than stepwise regression,while the two regression results were only slightly different.It was also suggested that local climate,especially local circulation and temperature,were important for the variations in total ozone,and the local climate could almost linearly explain 80% of the variance of total ozone.The relationship also indicated that the abrupt change of total ozone in the year 1994 may be related to abrupt local climate change.
文摘In this paper the grid data of total ozone mapping spectrograph (TOMS) installed on Nimbus 7 satellite (1978 to 1994) was used and the spatial and temporal distribution of total ozone over China was analyzed. The research indicates that the Qinghai Tibet Plateau destroyed the latitudinal distribution of total ozone of China and the low value closed center emerged over Qinghai Tibet Plateau. Long time change trends of seasonal total ozone of Qinghai Tibet Plateau are provided. It shows that the most obvious decrease of total ozone occurs in winter (Jan.), then in summer (Jul.), the relevant slow change occurs in autumn (Oct.) and spring (Apr.).
文摘Two statistical validation methods were used to evaluate the confidence level of the Total Column Ozone (TCO) measurements recorded by satellite systems measuring simultaneously, one using the normal distribution and another using the Mann-Whitney test. First, the reliability of the TCO measurements was studied hemispherically. While similar coincidences and levels of significance > 0.05 were found with the two statistical tests, an enormous variability in the levels of significance throughout the year was also exposed. Then, using the same statistical comparison methods, a latitudinal study was carried out in order to elucidate the geographical distribution that gave rise to this variability. Our study reveals that between the TOMS and OMI measurements in 2005 there was only a coincidence in 50% of the latitudes, which explained the variability. This implies that for 2005, the TOMS measurements are not completely reliable, except between the -50° and -15° latitude band in the southern hemisphere and between +15° and +50° latitude band in the northern hemisphere. In the case of OMI-OMPS, we observe that between 2011 and 2016 the measurements of both satellite systems are reasonably similar with a confidence level higher than 95%. However, in 2017 a band with a width of 20° latitude centered on the equator appeared, in which the significance levels were much less than 0.05, indicating that one of the measurement systems had begun to fail. In 2018, the fault was not only located in the equator, but was also replicated in various bands in the Southern Hemisphere. We interpret this as evidence of irreversible failure in one of the measurement systems.
基金funded by the Project 12ZB020 of the Education Department of Sichuan Province
文摘The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI （Ozone Monitoring Instrument Aerosol Index） data during 2005-007. The results show that there is a high correla- tion of At （the correlation coefficients are as high as 0.83 in March, 0.62 in April and 054 in May） between the Mongolia Gobi Desert and the west coast region of the United States （40°-50°N, 120°- 130°W）, indicating a strong source-receptor area relationship. Through calculating the lag correlation coefficient of the dust propagation time, we determined that the dust propagation lime fi＇om the Mongolia Gobi Desert to the west coast of the United States is about 6-7 days at the 99% confidence level.
基金The research is supported by the National Natural Science Foundation of China （Grant 40775009）；the National Basic Research Program of China （Grant 2006CB403706）.
文摘Using the Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical depth （AOD） at 500 nm data from 1980 to 2001 in north China, the spatial and temporal variations of AOD were examined. Seasonal AODs in Taklimakan Desert were 0.69 and 0.44 in spring and summer, respectively, which were mainly due to frequent occurrences of dust events in this region. Dust activities in spring also led to high aerosol loading in Gobi Desert and in northeast China where spring AODs were 0.33 and 0.29, respectively. Heavily impacted by events such as volcano eruption, forest fires and extraordinary dust storms, AODs showed large inter-annual variations. A decreasing tendency in AOD was observed in north China during 1980-1991, though a reverse tendency was revealed during 1997-2001, especially for spring AOD in northeast China. Further study is required to figure out how much human activities have contributed to the AOD tendency in north China.
