Spatial Distribution of CO2 Concentration over South America during ENSO Episodes by Using GOSAT Data

Carbon dioxide (CO2) is one of the most important greenhouse gases;its concentration and distribution have important implications on climate change. The El Ni?o Southern Oscillation (ENSO) is the Earth’s strongest climate fluctuation on inter-annual time scales and has global impacts. However, to date, there is no research on how ENSO affects the spatial distribution of CO2 concentration. In this study, we used spatial CO2 data from the ENVIronmentSATellite (ENVISAT) and the Greenhouse Gases Observing Satellite (GOSAT), the long duration monthly mean atmospheric CO2 from Mauna Loa Observatory, Multivariate ENSO Index (MEI) from Earth System Research Laboratory to analyze the way that ENSO affects spatial distribution of CO2 concentration in South America, which is affected by ENSO seriously. Our research revealed that monthly CO2 growth rate has a moderate, positive correlation relationship with MEI. We used geostatistics to predict and simulate the spatial distribution of CO2 and found that in south of 12°S, CO2 concentration of ENSO warm episode is lower than the one of ENSO cold and neutral episodes. ENSO impacts CO2 spatial distribution mainly in November, December, January and February;moderate-high concentration zone of ENSO warm episode more concentrates in the northern part of South America.

Vibration Effect and Damage Evolution Characteristics of Tunnel Surrounding Rock Under Cyclic Blasting Loading

Model test studies based on the similarity theory were conducted to investigate vibration effect and damage evolution characteristics of tunnel surrounding rock under push-type cyclic blasting excavation.The model was constructed with a ratio of 1∶15.By simulating the tunnel excavation of push-type cyclic blasting,the influence of the blasting parameter change on vibration effect was explored.The damage degree of tunnel surrounding rock was evaluated by the change of the acoustic wave velocity at the same measuring point after blasting.The relationship between the damage evolution of surrounding rock and blasting times was established.The research results show that：（1）In the same geological environment,the number of delay initiation is larger,the main vibration frequency of blasting seismic wave is higher,and the attenuation of high frequency signal in the rock and soil is faster.The influence of number of delay initiation on blasting vibration effect cannot be ignored;（2）Under push-type cyclic blasting excavation,there were great differences in the decreasing rates of acoustic wave velocity of the measuring points which have the same distance to the blasting region at the same depth,and the blasting damage ranges of surrounding rock were typically anisotropic at both depth and breadth;（3）When blasting parameters were basically kept as the same,the growth trend of the cumulative acoustic wave velocity decreasing rate at the measuring point was nonlinear under different cycle blasting excavations;（4）There were nonlinear evolution characteristics between the blasting cumulative damage（D）of surrounding rock and blasting times（n）under push-type cyclic blasting loading,and different measuring points had corresponding blasting cumulative damage propagation models,respectively.The closer the measuring point was away from the explosion source,the faster the cumulative damage extension.Blasting cumulative damage effect of surrounding rock had typically nonlinear evolution properties and anisotropic characteristics.

Analyzing CO_(2) concentration changes and their influencing factors in Indonesia by OCO-2 and other multi-sensor remote-sensing data

We used OCO-2 products and considered three factors that potentially affect CO_(2) concentration in Indonesia:sea surface temperature(SST),forest fires and vegetation.From 2014 to 2016,CO_(2) concentration in Indonesia showed a trend of increase,which is consistent with the global increase reported by the Greenhouse Gases Observing Satellite(GOSAT)Project.As an archipelago country,the results indicate that SST has a direct effect on the CO_(2) concentration in Indonesia.Their changing exhibits similar fluctuations;meanwhile,CO_(2) concentration and SST also presented positive correlation.In 2015,the number of fire hotspots suddenly increased to 140,699,because of occurrence of the worst forest fire.Due to special geographic conditions,forest fires did not induce CO_(2) concentration changes in Indonesia,but CO_(2) concentration in the corresponding islands showed a trend of increase.CO_(2) concentration increased in Kalimantan during the occurrence of forest fire in September–October 2014,and CO_(2) concentration increased in Kalimantan and Sumatra during the occurrence of forest fire in September–October 2015.Vegetation indices were stable and presented no correlation with CO_(2) concentration.This study demonstrated that OCO-2 is capable of monitoring CO_(2) concentration at a regional scale;additionally,an effective method for using OCO-2 Level 2 products is proposed.