Response of Growing Season Gross Primary Production to El Nino in Different Phases of the Pacific Decadal Oscillation over Eastern China Based on Bayesian Model Averaging

Gross primary production(GPP) plays a crucial part in the carbon cycle of terrestrial ecosystems.A set of validated monthly GPP data from 1957 to 2010 in 0.5°× 0.5° grids of China was weighted from the Multi-scale Terrestrial Model Intercomparison Project using Bayesian model averaging(BMA).The spatial anomalies of detrended BMA GPP during the growing seasons of typical El Nino years indicated that GPP response to El Nino varies with Pacific Decadal Oscillation(PDO) phases: when the PDO was in the cool phase,it was likely that GPP was greater in northern China(32°–38°N,111°–122°E) and less in the Yangtze River valley(28°–32°N,111°–122°E);in contrast,when PDO was in the warm phase,the GPP anomalies were usually reversed in these two regions.The consistent spatiotemporal pattern and high partial correlation revealed that rainfall dominated this phenomenon.The previously published findings on how El Nino during different phases of PDO affecting rainfall in eastern China make the statistical relationship between GPP and El Nino in this study theoretically credible.This paper not only introduces an effective way to use BMA in grids that have mixed plant function types,but also makes it possible to evaluate the carbon cycle in eastern China based on the prediction of El Nino and PDO.

Subdaily to Seasonal Change of Surface Energy and Water Flux of the Haihe River Basin in China: Noah and Noah-MP Assessment

The land surface processes of the Noah-MP and Noah models are evaluated over four typical landscapes in the Haihe River Basin(HRB) using in-situ observations. The simulated soil temperature and moisture in the two land surface models(LSMs) is consistent with the observation, especially in the rainy season. The models reproduce the mean values and seasonality of the energy fluxes of the croplands, despite the obvious underestimated total evaporation. Noah shows the lower deep soil temperature. The net radiation is well simulated for the diurnal time scale. The daytime latent heat fluxes are always underestimated, while the sensible heat fluxes are overestimated to some degree. Compared with Noah, Noah-MP has improved daily average soil heat flux with diurnal variations. Generally, Noah-MP performs fairly well for different landscapes of the HRB. The simulated cold bias in soil temperature is possibly linked with the parameterized partition of the energy into surface fluxes. Thus, further improvement of these LSMs remains a major challenge.

Sulfonated carbon dots modified IrO_(2)nanosheet as durable and high-efficient electrocatalyst for boosting acidic oxygen evolution reaction

Oxygen evolution reaction(OER)plays a crucial role in developing energy conversion and adjusting electronic structure of the electrocatalysts can effectively improve the catalytic activity and stability.However,it is a challenge to adjust the electronic structure on two-dimensional iridium dioxide nanosheets(IrO_(2)NS),which have the advantages of high atom utilization.Here,we regulate the surface properties of IrO_(2)NS through sulfonated carbon dots(SCDs)to promote the OER catalytic process.The catalyst IrO_(2)NS/SCDs-2 exhibited excellent catalytic activity with a lower overpotential of 180 mV than IrO_(2)NS(230 mV)at the current density of 10 mA·cm^(-2)in a 0.5 M H_(2)SO_(4) solution.And after 160 h of stability testing,the overpotential of IrO_(2)NS/SCDs-2 only decreased by 4 mV.Moreover,transient potential scanning test can visually demonstrate that the addition of SCDs improves the conductivity of the catalyst and increases the electron transfer rate.

Spatiotemporal variations of carbon flux and nitrogen deposition flux linked with climate change at the centennial scale in China

The spatial and temporal variations of the vegetation carbon flux in China from 1901 to 2005 were studied using the vegetation net primary production(NPP)values from seven Earth-system models.In addition,the temporal and spatial changes in the nitrogen deposition flux in China were studied using the NHx and NOy fluxes from 1901 to 2005.The relationship between changes in the carbon flux,nitrogen flux and climate was analyzed.The results show that(1)over the past 100 years,NPP in China has shown an upward trend.The average trend coefficient is 0.88 and the NPP distribution trend is generally low in the north and high in the south,with a gradual increase from the northwest to the southeast.Temperature,precipitation and radiation are all conducive to plant growth in the direction of the gradient.The correlation coefficients between the ensemble model mean NPP and temperature,precipitation,longwave radiation and shortwave radiation are 0.88,0.73,0.91 and 0.67,respectively.(2)In the past 100 years,the NHx and NOy fluxes in China have shown an upward trend,with trend coefficients of 0.98 and 0.98,respectively,which pass the 99.9%confidence level of the t-test.NHx and NOy fluxes are also generally low in the north and high in the south,with a gradual increase from the northwest to the southeast in a step-like pattern.(3)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and air temperature is similar,with only slight differences in values.The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and precipitation is similar in overall pattern,but the pattern is relatively complicated,with a positive-negative-positive-negative-positive pattern occurring across the monsoon region from north to south,and a negative-positive-negative-positive pattern occurring beyond the monsoon region from east to west.(4)The spatial distribution of the correlation coefficients between the NHx and NOy fluxes and NPP shows a generally consistent pattern,but the pattern is relatively uneven.The average distribution of the ensemble model mean is positive correlation in northeast China and southwest China,and alternating positive and negative correlation in other regions.