Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of co...Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.展开更多
Sea ice deformation parameters are important for elucidation of the properties and characteristics of ice-ocean models.Observations of sea ice motion over 11.5 year period(November 1996–April 2008) are used to calcul...Sea ice deformation parameters are important for elucidation of the properties and characteristics of ice-ocean models.Observations of sea ice motion over 11.5 year period(November 1996–April 2008) are used to calculate ice motion divergence and shear rates, and thus, to construct total deformation rate(TDR) estimates with respect to spatial and temporal variability in the Arctic Ocean. Strong sea ice deformation signal(SDS) rates are identified when TDR>0.01 day^(-1), and very strong SDS events,when TDR>0.05 day^(-1). These calculations are based on measurements made by the RADARSAT-1 Geophysical Processer System(RGPS). Statistical analysis of the SDS data suggest the following features:(1) Mean SDS and the SDS probability distributions are larger in "low latitudes" of the Arctic Ocean(less than 80°N) than in "high latitudes"(above 80°N), in both summer and winter;(2) very high SDS probabilities distributions and mean SDS values occur in coastal areas, e.g. the East Siberian Sea, Chukchi Sea and Beaufort Sea;(3) areas with relatively low TDR values, in the range from 0.01 day^(-1) to 0.05 day^(-1), cover much of the Arctic Ocean, in summer and winter;(4) of the entire TDR dataset, 45.89% belong to SDS, with summer the SDS percentage, 59.06%,and the winter SDS percentage, 40.50%. Statistically, the summer mean SDS, SDS percentage and very strong SDS are larger than corresponding values in the winter for each year, and show slight increasing tendencies during the years from 1997 to 2007.These results suggest important constraints for accurate simulations of very strong SDS in ice-ocean models.展开更多
The characteristics of internal tides in the upper layer of the Luzon Strait are investigated on the basis of direct-observation current data recorded on April 25 and September 26, 2008 by an acoustic Doppler current ...The characteristics of internal tides in the upper layer of the Luzon Strait are investigated on the basis of direct-observation current data recorded on April 25 and September 26, 2008 by an acoustic Doppler current profiler. Spectral analysis and energy estimation show that the diurnals and semidiurnals carry most of the energy of internal tides. Values of the depth-integrated total energy E for the three frequency bands of diurnal, semidiurnal, and high frequencies are 31, 6.9, and 3.4 kJ. m, respectively. Near-inertial peaks are only present in the baroclinic component. The behavior of typical tidal frequencies （i.e., O1, K1, M2, MK3, and M4） and the near-inertial frequency is basically consistent with linear internal wave theory, which predicts E＋（ω）/E_（ω）=（ω-f）2/（ω＋f）2 at depths above 66 m, while not all prominent tidal components coincide well with the relation of the linear internal wave field at other depths. Examinations of depth structures of the baroclinic tides and temporal variations show that the surface tides and internal tides are both of mixed type, having diurnal inequality and spring-neap fortnight periods. The K1 and O1 tides have comparable cross- and along-shelf components, while the M2 and S2 tides propagate toward the shelf in the northern South China Sea as wave beams. The amplitude and phase of internal tides vary with time, but M2 and S2 tides appear to have structures dominated by the first mode, while the K1 and O1 tides resemble second-mode structures. The minor to major axis ratios are close to expected values of flω in the thermocline.展开更多
Global change now poses a severe threat to the survival and development of mankind.Large-scale,real-time,highly accurate Earth observation from space has become a key technology used to observe global change.China is ...Global change now poses a severe threat to the survival and development of mankind.Large-scale,real-time,highly accurate Earth observation from space has become a key technology used to observe global change.China is one of the most influential countries affecting and being affected by global change,yet it has no scientific satellite for global change research so far.Developing global change scientific satellites not only would meet an important demand of China,but also would be a valuable contribution to the world.By analyzing the mechanisms of space-based observation of variables sensitive to global change,this paper explores the concept of global change scientific satellites,and proposes a series of global change scientific satellites to establish a scientific observation system for global environmental change monitoring from space.展开更多
基金funded by the National Basic Research Program of China (Grant No. 2012CB956203)the Strategic Priority Research Program-Climate Change: Carbon Budget and Relevant Issues of the Chinese Academy of Sciences (Grant No. XDA05090101)the Climate Change Special Fund of the China Meteorological Administration: Atmospheric Water Vapor Changes in China and Its Causes (Grant No. CCSF201330)
文摘Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.
基金supported by the Global Change Research Program of China (Grant No. 2015CB953901)the National Key Research and Development Program of China (Grant No. 2016YFC1401007)the Canadian Program on Energy Research and Development (OERD), the Office of Naval Research (Code 322, “Arctic and Global Prediction”, Grant Number and Principal Investigator: William Perrie, Grant No. N00014-15-1-2611)
文摘Sea ice deformation parameters are important for elucidation of the properties and characteristics of ice-ocean models.Observations of sea ice motion over 11.5 year period(November 1996–April 2008) are used to calculate ice motion divergence and shear rates, and thus, to construct total deformation rate(TDR) estimates with respect to spatial and temporal variability in the Arctic Ocean. Strong sea ice deformation signal(SDS) rates are identified when TDR>0.01 day^(-1), and very strong SDS events,when TDR>0.05 day^(-1). These calculations are based on measurements made by the RADARSAT-1 Geophysical Processer System(RGPS). Statistical analysis of the SDS data suggest the following features:(1) Mean SDS and the SDS probability distributions are larger in "low latitudes" of the Arctic Ocean(less than 80°N) than in "high latitudes"(above 80°N), in both summer and winter;(2) very high SDS probabilities distributions and mean SDS values occur in coastal areas, e.g. the East Siberian Sea, Chukchi Sea and Beaufort Sea;(3) areas with relatively low TDR values, in the range from 0.01 day^(-1) to 0.05 day^(-1), cover much of the Arctic Ocean, in summer and winter;(4) of the entire TDR dataset, 45.89% belong to SDS, with summer the SDS percentage, 59.06%,and the winter SDS percentage, 40.50%. Statistically, the summer mean SDS, SDS percentage and very strong SDS are larger than corresponding values in the winter for each year, and show slight increasing tendencies during the years from 1997 to 2007.These results suggest important constraints for accurate simulations of very strong SDS in ice-ocean models.
基金supported by National Basic Research Program of China (Grant Nos. 2007CB816003, 2011CB403503)International Cooperative Project of the Ministry of Science and Technology of China (Grant No. 2006DFB21630)+1 种基金Key Project of the National Natural Science Foundation of China (Grant No. 40520140073)the Scientific Research Fund of the Second Institute of Oceanography, SOA (Grant Nos. JG1009, JG0711 and JT0702)
文摘The characteristics of internal tides in the upper layer of the Luzon Strait are investigated on the basis of direct-observation current data recorded on April 25 and September 26, 2008 by an acoustic Doppler current profiler. Spectral analysis and energy estimation show that the diurnals and semidiurnals carry most of the energy of internal tides. Values of the depth-integrated total energy E for the three frequency bands of diurnal, semidiurnal, and high frequencies are 31, 6.9, and 3.4 kJ. m, respectively. Near-inertial peaks are only present in the baroclinic component. The behavior of typical tidal frequencies （i.e., O1, K1, M2, MK3, and M4） and the near-inertial frequency is basically consistent with linear internal wave theory, which predicts E＋（ω）/E_（ω）=（ω-f）2/（ω＋f）2 at depths above 66 m, while not all prominent tidal components coincide well with the relation of the linear internal wave field at other depths. Examinations of depth structures of the baroclinic tides and temporal variations show that the surface tides and internal tides are both of mixed type, having diurnal inequality and spring-neap fortnight periods. The K1 and O1 tides have comparable cross- and along-shelf components, while the M2 and S2 tides propagate toward the shelf in the northern South China Sea as wave beams. The amplitude and phase of internal tides vary with time, but M2 and S2 tides appear to have structures dominated by the first mode, while the K1 and O1 tides resemble second-mode structures. The minor to major axis ratios are close to expected values of flω in the thermocline.
基金supported by National Basic Research Program of China(Grant No.2009CB723900)
文摘Global change now poses a severe threat to the survival and development of mankind.Large-scale,real-time,highly accurate Earth observation from space has become a key technology used to observe global change.China is one of the most influential countries affecting and being affected by global change,yet it has no scientific satellite for global change research so far.Developing global change scientific satellites not only would meet an important demand of China,but also would be a valuable contribution to the world.By analyzing the mechanisms of space-based observation of variables sensitive to global change,this paper explores the concept of global change scientific satellites,and proposes a series of global change scientific satellites to establish a scientific observation system for global environmental change monitoring from space.
