The temporal and spatial variations of surface latent heat flux (SLHF) before and after the Mw9.0 earthquake that occurred on the west coast of Sumatra, Indonesia on 26 December 2004 are summarized. It is found that b...The temporal and spatial variations of surface latent heat flux (SLHF) before and after the Mw9.0 earthquake that occurred on the west coast of Sumatra, Indonesia on 26 December 2004 are summarized. It is found that before the earthquake significant SLHF anomalies occurred at the epicentral area and its vicinity. The largest SLHF anomaly oc- curred on the subduction zone in the middle part of Burma micro-plate, where the middle part of the rup- ture zone is located and the aftershocks are concen- trated. The developments of the anomaly involved growing of the anomaly from small to large and spreading of the anomaly from disordered to con- centrated. The anomaly began to occur on the east extensional boundary of the Burma micro-plate and its adjacent oceanic basin, and then propagated to the west compressive boundary, where the subduc- tion zone exists. Finally, the anomaly disappeared after the main shock. The seismic source is consid- ered to be a dissipation system. The increase of stress prior to an earthquake may enhance the ex- change of energy and material between the seismic source system and the outer system, resulting in the increase of the rate of energy exchange between sea surface and atmosphere, which is believed to be the main reason of the generation of SLHF anomaly.展开更多
The temporal and spatial variations of the ten-day mean surface latent heat flux (TMLH) have been analyzed in this paper based on the data of NCEP from January of 1979 to December of 1995 in the South China Sea (SCS) ...The temporal and spatial variations of the ten-day mean surface latent heat flux (TMLH) have been analyzed in this paper based on the data of NCEP from January of 1979 to December of 1995 in the South China Sea (SCS) monsoon region. It is found that there exist maximum centers of TMLH standard deviation in the northwest Indochina and the Indian Peninsula as well as the western Pacific, SCS, the Indian Ocean and the Bay of Bengal, and their locations and strengths change significantly during the period of SCS monsoon onset. A positive zonal deviation of TMLH occurs first in the Indochina Peninsula, apparently earlier than that in the Indian Peninsula. The appearance of maximum positive zonal deviations of TMLH approximately coincides with the summer monsoon onset. Over the Indochina and Indian Peninsulas, the TMLH increases gradually with a small amplitude of variation before the onset of summer monsoon, and the rate of increase is significantly enhanced after the onset of the monsoon; whereas over the ocean, TMLH decreases before the monsoon onset, varies little during the period of monsoon and increases gradually after the ending of monsoon. Therefore, it seems that the surface latent heat flux plays an important role in the maintenance of the summer monsoon, and its variation is an phenomenon accompanying the onset of summer monsoon.展开更多
By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 M S 7.1 New Zealand earthquake, an isolated SLHF positive anomaly ...By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 M S 7.1 New Zealand earthquake, an isolated SLHF positive anomaly on Aug. 1, 2010 was found with a high value of about 160 W/m 2 to the northeast of the epicenter. Historical data, background pixels, and wavelet transforms of time series were comprehensively analyzed to study the spatiotemporal features of the SLHF anomaly. After removing the influences of wind speed and cloud cover, the key factor leading to local SLHF anomalies is the surface temperature increment. Combined with GPS displacement observations and tectonic settings, we determined that the physical mechanism of the SLHF anomaly could possibly be attributed to hot underground materials related to high-temperature and high-pressure upwelling from the deep crust and mantle along the nearby subduction zone, thereby explaining the local temperature increment to the northeast of the epicenter, as well as in the center of the North Island and the southwest of the South Island. Furthermore, it changed the specific humidity between the ground and surface air, causing the local SLHF increment.展开更多
利用1981—2015年ERA-Interim再分析资料和青海省43个观测站气象资料,采用气象经验正交函数分解(EOF)、相关分析法及合成分析等方法,对青藏高原(以下简称高原) 5—10月地表潜热通量的时空分布特征及其与青海省同期降水之间的关系进行了...利用1981—2015年ERA-Interim再分析资料和青海省43个观测站气象资料,采用气象经验正交函数分解(EOF)、相关分析法及合成分析等方法,对青藏高原(以下简称高原) 5—10月地表潜热通量的时空分布特征及其与青海省同期降水之间的关系进行了分析,结果表明:(1)高原地表潜热通量第1模态空间分布主要呈现高原东西部变化不一致的特征,青海东北部、高原西部和南部地区表现为正异常,其余地区为负异常;第1模态时间系数呈现显著下降趋势,并以2001年为界,前正后负,表明青海东北部及高原西部和南部地表潜热通量在2001年以前(后)增加(减少)。(2)高原地表潜热通量与青海省东北部降水存在显著的负相关关系,当高原地表潜热通量增加(减少)时,青海省东北部降水减少(增加)。(3)将通过0. 1显著性检验的区域作为研究二者之间关系的关键区(35. 0°～38. 5°N,98°～103. 0°E),以1个标准差为依据,挑选潜热通量高值年和低值年。结果表明,关键区内地表潜热通量在近35 a表现为显著下降的趋势,潜热通量高值年关键区降水增加,潜热通量低值年关键区东北部降水减少,其余地区降水增加,且在南部存在大于60 mm正异常中心;在潜热通量高(低)值年,关键区位势偏低(高),风速偏大(小),关键区南部水汽辐合较弱(强)。通过分析100 hP a南亚高压中心强度与300 hP a温度场,在地表潜热通量异常偏高(低)年,南亚高压强度略低(高),300 hP a暖中心略低(高),且南亚高压初上(撤离)高原较早。展开更多
Using data from the National Center for Environmental Prediction （NCEP）, the paper analyzed the surface latent heat flux （SLHF） variations for five inland earthquakes occurred in some lake area, moist area and ari...Using data from the National Center for Environmental Prediction （NCEP）, the paper analyzed the surface latent heat flux （SLHF） variations for five inland earthquakes occurred in some lake area, moist area and arid area of China during recent years. We used the SLHF daily and monthly data to differentiate the global and seasonal variability from the transient local anomalies. The temporal scale of the observed variations is 1-2 months before and after the earthquakes, and spatial scale is about 10°×10°. The result suggests that the SLHFs adjacent the epicenters all are anomalous high value （〉μ＋2σ） 8-30 days before the shocks as compared with past several years of data. Different from the abnormal meteorological phenomenon, the distribution of the anomalies was isolated and local, which usually occurred in the epicenter and its adjacent area, or along the fault lines. The increase of SLHF was tightly related with the season which the earthquake occurs in; the maximal （125 W/m^2, Pu＇er earthquake） and minimal （25 W/m^2, Gaize earthquake） anomalies were in summer and winter, respectively. The abundant surface water and groundwater in the epicenter and its adjacent region can provide necessary condition for the change of SLHF. To further confirm the reliability of SLHF anomaly, it is necessary to explore its physical mechanism in depth by more earthquake cases.展开更多
利用NCAR/NCEP1948年1月-2002年12月共55 a 660个月的地表感热通量和地表潜热通量以及其它气象场的月平均再分析资料,计算了期间5-6月平均的南海夏季风湿位涡强度指数。由标准化的湿位涡强度指数距平的年际变化曲线,选择距平值大于0.5...利用NCAR/NCEP1948年1月-2002年12月共55 a 660个月的地表感热通量和地表潜热通量以及其它气象场的月平均再分析资料,计算了期间5-6月平均的南海夏季风湿位涡强度指数。由标准化的湿位涡强度指数距平的年际变化曲线,选择距平值大于0.5的年份为季风爆发的强年,距平值小于-0.5的年份为季风爆发的弱年,对强、弱年东亚及其周边地区的地表潜热通量(LHF)距平、地表感热通量(SHF)距平以及海平面气压(SLP)距平的分布特征进行了合成分析。结果表明,在南海夏季风爆发强年和弱年,其前期冬春季的地表潜热通量、感热通量以及海平面气压场的距平分布有很大不同,前冬的差别更为明显。冬季,LHF和SHF在强、弱年的主要差异在海洋上和近海地区,尤其是西太平洋沿岸,合成距平呈现沿海岸线的东北-西南向的带状分布,强年沿岸为正距平,弱年为负距平。LHF和SHF标准化距平叠加之和有同样的区域分布特征。这种强、弱年的距平分布差异,与低层风场在强、弱年的不同有密切关系,强年东亚冬季风偏强,弱年则反之。强、弱年SLP在前冬的距平差异,验证了上述结论。展开更多
潜热通量产品的验证与分析对于研究气候变化及能量循环具有重要意义。全球陆表高分辨率蒸散产品(high resolution global lAnd surface evapotranspiration product,Hi-GLASS ET)融合了5种传统蒸散算法,能够生产出较高精度的陆表潜热通...潜热通量产品的验证与分析对于研究气候变化及能量循环具有重要意义。全球陆表高分辨率蒸散产品(high resolution global lAnd surface evapotranspiration product,Hi-GLASS ET)融合了5种传统蒸散算法,能够生产出较高精度的陆表潜热通量产品,但目前没有针对此产品的验证研究。利用Ameriflux通量观测站点的潜热通量观测值与相应的Hi-GLASS陆表潜热通量产品估算值进行对比,获取多组有效验证数据。验证结果显示,所选站点实际观测值与产品估算值的决定系数(R 2)为0.6,均方根误差(RMSE)为34.4 W/m^(2),平均偏差(Bias)为-13.4 W/m^(2),克林-古普塔效率(Kling-Gupta efficiency,KGE)为0.49,Hi-GLASS潜热通量产品具有较高的精度,算法的拟合结果较好;此外,空间分布也表明Hi-GLASS陆表潜热通量产品符合正常的自然规律。由于数据获取的局限性,仅采用了美国地区18个站点数据对产品进行验证,在其他地区仍需进一步验证。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40372131)the Key Projects Required by National 10th Five-year Plan(Grant No.2004BA601B01-02-02)the National High-tech"863"Project(Grant No.2003AA134060).
文摘The temporal and spatial variations of surface latent heat flux (SLHF) before and after the Mw9.0 earthquake that occurred on the west coast of Sumatra, Indonesia on 26 December 2004 are summarized. It is found that before the earthquake significant SLHF anomalies occurred at the epicentral area and its vicinity. The largest SLHF anomaly oc- curred on the subduction zone in the middle part of Burma micro-plate, where the middle part of the rup- ture zone is located and the aftershocks are concen- trated. The developments of the anomaly involved growing of the anomaly from small to large and spreading of the anomaly from disordered to con- centrated. The anomaly began to occur on the east extensional boundary of the Burma micro-plate and its adjacent oceanic basin, and then propagated to the west compressive boundary, where the subduc- tion zone exists. Finally, the anomaly disappeared after the main shock. The seismic source is consid- ered to be a dissipation system. The increase of stress prior to an earthquake may enhance the ex- change of energy and material between the seismic source system and the outer system, resulting in the increase of the rate of energy exchange between sea surface and atmosphere, which is believed to be the main reason of the generation of SLHF anomaly.
基金Supported by the National Natural Science Foundation of China under the grants 49735170.
文摘The temporal and spatial variations of the ten-day mean surface latent heat flux (TMLH) have been analyzed in this paper based on the data of NCEP from January of 1979 to December of 1995 in the South China Sea (SCS) monsoon region. It is found that there exist maximum centers of TMLH standard deviation in the northwest Indochina and the Indian Peninsula as well as the western Pacific, SCS, the Indian Ocean and the Bay of Bengal, and their locations and strengths change significantly during the period of SCS monsoon onset. A positive zonal deviation of TMLH occurs first in the Indochina Peninsula, apparently earlier than that in the Indian Peninsula. The appearance of maximum positive zonal deviations of TMLH approximately coincides with the summer monsoon onset. Over the Indochina and Indian Peninsulas, the TMLH increases gradually with a small amplitude of variation before the onset of summer monsoon, and the rate of increase is significantly enhanced after the onset of the monsoon; whereas over the ocean, TMLH decreases before the monsoon onset, varies little during the period of monsoon and increases gradually after the ending of monsoon. Therefore, it seems that the surface latent heat flux plays an important role in the maintenance of the summer monsoon, and its variation is an phenomenon accompanying the onset of summer monsoon.
基金supported by the National Basic Research Program of China (2011CB707102)the Fundamental Research Funds for the Central Universities (2010YD01)the Program of Scientific and Technological Cooperation Between Italy and China (SAGA-4-EPR)
文摘By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 M S 7.1 New Zealand earthquake, an isolated SLHF positive anomaly on Aug. 1, 2010 was found with a high value of about 160 W/m 2 to the northeast of the epicenter. Historical data, background pixels, and wavelet transforms of time series were comprehensively analyzed to study the spatiotemporal features of the SLHF anomaly. After removing the influences of wind speed and cloud cover, the key factor leading to local SLHF anomalies is the surface temperature increment. Combined with GPS displacement observations and tectonic settings, we determined that the physical mechanism of the SLHF anomaly could possibly be attributed to hot underground materials related to high-temperature and high-pressure upwelling from the deep crust and mantle along the nearby subduction zone, thereby explaining the local temperature increment to the northeast of the epicenter, as well as in the center of the North Island and the southwest of the South Island. Furthermore, it changed the specific humidity between the ground and surface air, causing the local SLHF increment.
文摘利用1981—2015年ERA-Interim再分析资料和青海省43个观测站气象资料,采用气象经验正交函数分解(EOF)、相关分析法及合成分析等方法,对青藏高原(以下简称高原) 5—10月地表潜热通量的时空分布特征及其与青海省同期降水之间的关系进行了分析,结果表明:(1)高原地表潜热通量第1模态空间分布主要呈现高原东西部变化不一致的特征,青海东北部、高原西部和南部地区表现为正异常,其余地区为负异常;第1模态时间系数呈现显著下降趋势,并以2001年为界,前正后负,表明青海东北部及高原西部和南部地表潜热通量在2001年以前(后)增加(减少)。(2)高原地表潜热通量与青海省东北部降水存在显著的负相关关系,当高原地表潜热通量增加(减少)时,青海省东北部降水减少(增加)。(3)将通过0. 1显著性检验的区域作为研究二者之间关系的关键区(35. 0°～38. 5°N,98°～103. 0°E),以1个标准差为依据,挑选潜热通量高值年和低值年。结果表明,关键区内地表潜热通量在近35 a表现为显著下降的趋势,潜热通量高值年关键区降水增加,潜热通量低值年关键区东北部降水减少,其余地区降水增加,且在南部存在大于60 mm正异常中心;在潜热通量高(低)值年,关键区位势偏低(高),风速偏大(小),关键区南部水汽辐合较弱(强)。通过分析100 hP a南亚高压中心强度与300 hP a温度场,在地表潜热通量异常偏高(低)年,南亚高压强度略低(高),300 hP a暖中心略低(高),且南亚高压初上(撤离)高原较早。
文摘Using data from the National Center for Environmental Prediction （NCEP）, the paper analyzed the surface latent heat flux （SLHF） variations for five inland earthquakes occurred in some lake area, moist area and arid area of China during recent years. We used the SLHF daily and monthly data to differentiate the global and seasonal variability from the transient local anomalies. The temporal scale of the observed variations is 1-2 months before and after the earthquakes, and spatial scale is about 10°×10°. The result suggests that the SLHFs adjacent the epicenters all are anomalous high value （〉μ＋2σ） 8-30 days before the shocks as compared with past several years of data. Different from the abnormal meteorological phenomenon, the distribution of the anomalies was isolated and local, which usually occurred in the epicenter and its adjacent area, or along the fault lines. The increase of SLHF was tightly related with the season which the earthquake occurs in; the maximal （125 W/m^2, Pu＇er earthquake） and minimal （25 W/m^2, Gaize earthquake） anomalies were in summer and winter, respectively. The abundant surface water and groundwater in the epicenter and its adjacent region can provide necessary condition for the change of SLHF. To further confirm the reliability of SLHF anomaly, it is necessary to explore its physical mechanism in depth by more earthquake cases.
文摘利用NCAR/NCEP1948年1月-2002年12月共55 a 660个月的地表感热通量和地表潜热通量以及其它气象场的月平均再分析资料,计算了期间5-6月平均的南海夏季风湿位涡强度指数。由标准化的湿位涡强度指数距平的年际变化曲线,选择距平值大于0.5的年份为季风爆发的强年,距平值小于-0.5的年份为季风爆发的弱年,对强、弱年东亚及其周边地区的地表潜热通量(LHF)距平、地表感热通量(SHF)距平以及海平面气压(SLP)距平的分布特征进行了合成分析。结果表明,在南海夏季风爆发强年和弱年,其前期冬春季的地表潜热通量、感热通量以及海平面气压场的距平分布有很大不同,前冬的差别更为明显。冬季,LHF和SHF在强、弱年的主要差异在海洋上和近海地区,尤其是西太平洋沿岸,合成距平呈现沿海岸线的东北-西南向的带状分布,强年沿岸为正距平,弱年为负距平。LHF和SHF标准化距平叠加之和有同样的区域分布特征。这种强、弱年的距平分布差异,与低层风场在强、弱年的不同有密切关系,强年东亚冬季风偏强,弱年则反之。强、弱年SLP在前冬的距平差异,验证了上述结论。
