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P182; 根据ACE／ULEIS卫星数据，确定了2007?05—2010?01太阳活动极小期内的3个独立富3 He 太阳高能粒子（ SEP ）事件，并结合 STEREO 双星对相同事件的观测数据，研究了事件中电子的经向分布特征。结果表明：由耀斑引起的3个独立SEP 事件，电子的经向分布宽度可达到130°。计算表明，携带电子传播的日面波传播速度差异显著，电子的此类经向分布很可能是由于其在日面横向扩散所致。当观测点磁力线足点位于耀斑源区东侧时，电子的日面扩散速度更快。

合成孔径雷达差分干涉(InSAR)测量技术是最近30年来发展迅速的空间对地观测技术。相对传统测量技术,该技术具有精度高、覆盖范围广、不受天气状况影响等优势,已在区域性沉降监测、灾害监测评估、能源资源勘查等非常广阔的领域展现了它的应用潜力。SAR卫星影像质量不够高是制约该技术精度提升和应用范围扩展的一大因素。

Satellite observations of atmospheric CO2 are able to truly capture the variation of global and regional CO2 concentration. The model simulations based on atmospheric transport models can also assess variations of atmospheric CO2 concentrations in a continuous space and time, which is one of approaches for qualitatively and quantitatively studying the atmospheric transport mechanism and spatio-temporal variation of atmospheric CO2 in a global scale. Satellite observations and model simulations of CO2 offer us two different approaches to understand the atmospheric CO2. However, the difference between them has not been comprehensively compared and assessed for revealing the global and regional features of atmospheric CO2. In this study, we compared and assessed the spatio-temporal variation of atmospheric CO2 using two datasets of the column-averaged dry air mole fractions of atmospheric CO2（XCO2） in a year from June 2009 to May 2010, respectively from GOSAT retrievals（V02.xx） and from Goddard Earth Observing System-Chemistry（GEOS-Chem）, which is a global 3-D chemistry transport model. In addition to the global comparison, we further compared and analyzed the difference of CO2 between the China land region and the United States（US） land region from two datasets, and demonstrated the reasonability and uncertainty of satellite observations and model simulations. The results show that the XCO2 retrieved from GOSAT is globally lower than GEOS-Chem model simulation by 2 ppm on average, which is close to the validation conclusion for GOSAT by ground measures. This difference of XCO2 between the two datasets, however, changes with the different regions. In China land region, the difference is large, from 0.6 to 5.6 ppm, whereas it is 1.6 to 3.7 ppm in the global land region and 1.4 to 2.7 ppm in the US land region. The goodness of fit test between the two datasets is 0.81 in the US land region, which is higher than that in the global land region（0.67） and China land region（0.68）. The analysis results further indicate that the inconsistency of CO2 concentration between satellite observations and model simulations in China is larger than that in the US and the globe. This inconsistency is related to the GOSAT retrieval error of CO2 caused by the interference among input parameters of satellite retrieval algorithm, and the uncertainty of driving parameters in GEOS-Chem model.

Long-term highly accurate surface soil moisture data of TP （Tibetan Plateau） are important to the research of Asian monsoon and global atmospheric circulation. However, due to the sparse in-situ networks, the lack of soil moisture observations has se- riously hindered the progress of climate change researches of TP. Based on the Dual-Channel soil moisture retrieval algorithm and the satellite observation data of AMSR-E （Advanced Microwave Scanning Radiometer for EOS）, we have produced the surface soil moisture data of TP from 2003 to 2010 and analyzed the seasonal characteristic of the soil moisture spatial distri- bution and its multi-year changing trend in area of TP. Compared to the in-situ observations, the accuracy of the soil moisture retrieved by the proposed algorithm is evaluated. The evaluation result shows that the new soil moisture product has a better accuracy in the TP region than the official product of AMSR-E. The spatial distribution of the annual mean values of soil moisture and the seasonal variations of the monthly-averaged soil moisture are analyzed. The results show that the soil mois- ture variations in space and time are consistent with the precipitation distribution and the water vapor transmission path in TP. Based on the new soil moisture product, we also analyzed the spatial distribution of the changing trend of multi-year soil moisture in TP. From the comparisons with the precipitation changing trend obtained from the meteorological observation sites in TP, we found that the spatial pattern of the changing trend of soil moisture coincides with the precipitation as a whole.

Atmospheric SO_2 has a significant impact on the urban environment and global climate. Band Residual Difference Algorithm（BRD） and Differential Optical Absorption Spectroscopy（DOAS） were used respectively by NASA and ESA science team to derive SO_2 columns from satellite observations, but there are few studies on the comparison and validation of BRD and DOAS SO_2 retrievals under the same observation conditions. In this study, the radiative transfer model SCIATRAN was firstly used to validate the accuracies of BRD and DOAS SO_2 retrievals, and analyse the uncertainty of SO_2 retrieval caused by band selection,O_3 absorption, aerosol, surface reflectance, solar and viewing zenith angle. Finally, BRD and DOAS algorithms were applied to the same radiances from satellite observations, and comparisons of BRD and DOAS SO_2 retrievals were conducted over volcanic eruption and North China. Results show that, for the case with low SO_2 columns, BRD SO_2 retrievals have higher retrieval accuracy than DOAS, but typical seasonal variation with high SO_2 column in winter and low in summer can be more clearly discernible in DOAS SO_2 retrievals than BRD from satellite observations. For the case with high SO_2 columns, the differences between BRD（310.8–314.4 nm） and DOAS（315–327 nm） retrievals are large, and the value and accuracy of BRD（310.8–314.4 nm） SO_2 retrievals are lower than those of DOAS（315–327 nm） retrievals. Compared with the SO_2 inputs in forward model, both BRD（310.8–314.4 nm） and DOAS（315–327 nm） SO_2 retrievals are underestimated for the case with high SO_2 columns. The selection of wavelength range can significantly affect the accuracy of SO_2 retrieval. The error of BRD SO_2 retrieval from 310.8–314.4 nm is lower than other bands in the ultraviolet spectral region（306–327 nm）. The increase of wavelength in the ultraviolet spectral region306–330 nm can reduce the underestimation of DOAS SO_2 retrievals in the case of high SO_2 column, but slight overestimation of SO_2 retrieval is found from the 315–327 nm range in the case of low SO_2 column. The values of BRD and DOAS SO_2 retrieval decrease with atmospheric O_3 column and aerosol optical depth increasing, but increase with surface reflectance increasing. Large solar zenith angle and viewing zenith angle can introduce more errors to the BRD and DOAS SO_2 retrievals. This study is important for the improvement of retrieval algorithm and the application of SO_2 products from satellite observations.

The summertime ozone valley over the Tibetan Plateau is formed by two influences,the Asian summer monsoon（ASM） and air column variations.Total ozone over the Tibetan Plateau in summer was ～33 Dobson units（DU） lower than zonal mean values over the ocean at the same latitudes during the study period 2005-2009.Satellite observations of ozone profiles show that ozone concentrations over the ASM region have lower values in the upper troposphere and lower stratosphere（UTLS） than over the non-ASM region.This is caused by frequent convective transport of low-ozone air from the lower troposphere to the UTLS region combined with trapping by the South Asian High.This offset contributes to a ～20-DU deficit in the ozone column over the ASM region.In addition,along the same latitude,total ozone changes identically with variations of the terrain height,showing a high correlation with terrain heights over the ASM region,which includes both the Tibetan and Iranian plateaus.This is confirmed by the fact that the Tibetan and Iranian plateaus have very similar vertical distributions of ozone in the UTLS,but they have different terrain heights and different total-column ozone levels.These two factors（lower UTLS ozone and higher terrain height） imply 40 DU in the lower-ozone column,but the Tibetan Plateau ozone column is only ～33 DU lower than that over the non-ASM region.This fact suggests that the lower troposphere has higher ozone concentrations over the ASM region than elsewhere at the same latitude,contributing ～7 DU of total ozone,which is consistent with ozonesonde and satellite observations.

For the Pearl River plume, the supercritical, distinct plume front appears in downwelling-favorable winds, which is easily observed due to the distinct boundary between the plume water and the ambient water. In this paper, in situ and satellite observations of a plume front are utilized to explore the Pearl River plume front properties under the downwelling-favorable winds. Field observations clearly show frontal structure, especially the two-layer structure in the plume water and the downward-motion of water in the frontal region. The Advanced Synthetic Aperture Radar （ASAR） images are also analyzed to unveil the plume front： there is a white stripe on the west side out of the river mouth under downwelling-favorable winds, which is identified as a supercritical plume front, and the width of the plume front is about 250 m. The normalized velocity gradient shows the intense velocity convergence in the front region. Also, analyses of ASAR images imply that the river discharge plays an important role in controlling the location and shape of the front.

In this research, we normalized the character- istics of ocean eddies by using satellite observation of the Sea Level Anomaly （SLA） data to determine the most typical shape of ocean eddies. This normalization is based on modified analytic functions with nonlinear optimal fitting. The most typical eddy is the Taylor vortex （~50%）, which exhibits a Gaussian-shaped exp（-r2） SLA and a vorticity distribution of （1-rZ）exp（-r2） as a function of the normalized radii r. The larger the amplitude of the eddy, the more likely the eddy is to be Gaussian-shaped. Furthermore, approximately 40% of ocean eddies are combinations of two Gaussian eddies with different parameters, but the composition of these types of eddies is more like a quadratic eddy than a Gaussian one. Only a small portion of oceanic eddies are pure quadratic eddies （ 〈 10%） with the same vorticity distribution as a Rankine vortex. We concluded that the Taylor vortex is a good approximation of the typical shape of ocean eddies.

Outflowing ion beams forming four successive inverted-V structures in the energy-time spectrograms of H^＋, He^＋, and O^＋ were observed at an altitude of 3.4 R_E by Cluster satellites travelling above the auroral acceleration region （AAR） in the southern hemisphere on February 14, 2001. Energization by negative U-shaped potential structures in the AAR is believed to be responsible for the formation of these outflowing ion inverted-V structures. Thus, utilizing the different motion properties of the three ion species, the altitude of the upper boundary of the AAR is estimated to be -11100 km. Moreover, based on multi-satellite observations, each of these U-shaped potential structures involved in this event crosses the latitudinal direction at -0.4°–1° invariantlatitude （ILAT）, moving poleward at an average speed of -0.2° ILAT per minute, before disappearing at -71.5° ILAT.

A strong urban heat island （UHI） appeared in a hot weather episode in Suzhou City during the period from 25 July to 1 August 2007. This paper analyzes the urban heat island characteristics of Suzhou City under this hot weather episode. Both meteorological station observations and MODIS satellite observations show a strong urban heat island in this area. The maximum UHI intensity in this hot weather episode is 2.2℃, which is much greater than the summer average of 1.0℃ in this year and the 37–year （from 1970 to 2006） average of 0.35℃. The Weather Research and Forecasting （WRF） model simulation results demonstrate that the rapid urbanization processes in this area will enhance the UHI in intensity, horizontal distribution, and vertical extension. The UHI spatial distribution expands as the urban size increases. The vertical extension of UHI in the afternoon increases about 50 m higher under the year 2006 urban land cover than that under the 1986 urban land cover. The conversion from rural land use to urban land type also strengthens the local lake-land breeze circulations in this area and modifies the vertical wind speed field.