The status and development proposal of carbon sources and sinks monitoring satellite system

In order to mitigate global warming,the international communities actively explore low-carbon and green development methods.According to the Paris Agreement that came into effect in 2016,there will be a global stocktaking plan to carry out every 5 years from 2023 onwards.In September 2020,China proposed a"double carbon"target of carbon peaking before 2030 and carbon neutrality before 2060.Achieving carbon peaking and carbon neutrality goals requires accurate carbon emissions and carbon absorptions.China’s existing carbon monitoring methods have insufficient detection accuracy,low spatial resolution,and narrow swath,which are difficult to meet the monitoring requirement of carbon sources and sinks monitoring.In order to meet the needs of carbon stocktaking and support the monitoring and supervision of carbon sources and sinks,it is recommended to make full use of the foundation of the existing satellites,improve the detection technical specifications of carbon sources and sinks monitoring measures,and build a multi-means and comprehensive,LEO-GEO orbit carbon monitoring satellite system to achieve higher precision,higher resolution and multi-dimensional carbon monitoring.On this basis,it is recommended to strengthen international cooperation,improve data sharing policy,actively participate in the development of carbon retrieval algorithm and the setting of international carbon monitoring standards,establish an independent and controllable global carbon monitoring and evaluation system,and contribute China’s strength to the global realization of carbon peaking and carbon neutrality.

The impacts of modeling global CO2 concentrations with GEOS-Chem using different ocean carbon fluxes

The rise in atmospheric carbon dioxide(C02)concentrations caused by human activities is leading to global climate change,which poses a threat to human development and survival.This study analyzed the distribution of the ocean carbon flux with interannual changes and compared it with the climatological ocean carbon flux to deepen our understanding of carbon sources and sinks.To simulate global CO2 concentrations for the years2008-2010,the ocean carbon flux with interannual changes and the climatological ocean carbon flux were used to drive the GEOS-Chem model,an atmospheric chemical transport model.The simulated values were compared with the CO2 concentrations at nine observation stations to explore the influence of interannual changes in the ocean carbon fluxes on the simulated CO2 concentrations.The authors found that the difference between the two simulation results was greater in the Southern Hemisphere all year,and the difference in autumn was the largest.Compared with the observations,the simulated CO2 concentration of the ocean carbon flux with interannual changes is closer to the observations,indicating that this simulation is more accurate.

Modulation of land-sea thermal contrast on the energy source and sink of tropical cyclone activity and its annual cycle

In general,the tropical cyclone(TC) activity is considered to be influenced by the heat content of underlying ocean,vertical shear of horizontal wind,vorticity in the low troposphere,moisture in the troposphere,and favorable condition for deep convection development.However,these factors by nature merely present the internal factors of either atmosphere or ocean which influence the TC activity.In fact,the energy budget of the Earth system and its variation,modulated by the land-sea thermal contrast,are the intrinsic reasons responsible for the variation of TC activity.Here we investigate the modulation of diabatic heating distribution associated with the land-sea thermal contrast on the distribution of TC activity energy source and sink as well as the seasonality.An accumulated energy increment index(AEI) is defined using the TC best track data,and the energy sources and sinks of TC activity are then diagnosed effectively and practically according to the distribution of AEI.Results show that the thermal contrast of land and ocean is the primary reason for asymmetric distribution of TC activity about the Equator as well as the zonally asymmetric distribution of TC activity.The energy sources of TC activity are dominated by condensation heating of deep convection or double-dominant heating,which includes the condensation heating and cooling of longwave radiation(LO),while the sink areas are dominated by LO.The large scale diabatic heating associated with land-sea thermal contrast results in more favorable conditions for TC activity over the west part of oceans than those over the east parts.Moreover,the intensity of interaction of different diabatic heating over the west and east parts of ocean is also affected by the zonal scale of the oceans,which induces the difference of TC activity over the western North Pacific(WNP) and North Atlantic(ATL).The favorable westerlies and anticyclonic vertical shear associated with the tropical zonally asymmetric diabatic heating also contribute to the most intense TC activity over the WNP.The variation of large scale diabatic heating modulates the annual cycle of TC energy sources and sinks.In particular,the annual cycle over the WNP is the most typical one among the three basins(the WNP,the south Indian Ocean,and western South Pacific) that are characterized by the meridional shift of the energy sources and sinks.However,sources over the eastern North Pacific tend to extend westward and withdraw eastward associated with the variation of LO,while over the ATL,sources always merge from small pieces into a big one as the different diabatic heating over its west and east parts interacts with each other.Over the boreal Indian Ocean,the subcontinental scale land-sea heating contrast modifies the large scale circulation,and consequently contributes to the bimodal annual cycle of TC activity.In summary,TC activities are closely related to the interaction among various components of the climate system more than the atmosphere and ocean.

Numerical Study on Microphysical Processes of Two Different Snowfall Cases in Northern China

In this paper, two snowfall cases under different weather conditions in northern China are simulated by using the meso scale model MM5. Two-way nesting structure of domains is designed for each case. Among the explicit schemes of MM5, the Reisner graupel scheme is selected to describe the microphysical process. The simulated snow-bands of two cases are basically consistent with observations. The simulated results of microphysical processes are mainly discussed. The hydrometeors and their sources and sinks under different weather backgrounds are described. The feedback effects of microphysical processes on the thermal and dynamic processes are also discussed. Method that outputs the accumulative sources and sinks per hour is used to analyze the distribution characteristics of hydrometeors during the strongest snowfall period. Two sensitivity tests （called heat test and drag test） are conducted to examine the effects of microphysical processes on cloud produced by the latent heat and drag force. Results have shown that the distribution of particles has a close relation with temperature. The temperature of Beijing snowfall is under 0℃ and there exist vapor and solid phase particles, while Liaoning snowfall has vapor, liquid, and solid phase particles due to the warm temperature. The distribution of these particles is not the same at different development stages. From the analyses of the characteristics of sources and sinks, it is found that snow is mainly produced by the deposition and accretion with ice. Cloud water is crucial to graupel. The melting of ice-phase particles enhances the rain production. The results of heat tests and drag tests reveal that the microphysical processes have interacted with the dynamic and thermal processes. Latent heat release of hydrometeors feeds back positively on snowfall while the drag force not. At last, comparisons of simulated results have been done between the two different kinds of snowfall cases. The microphysical processes of Liaoning snowfall case is more complicated than those of Beijing snowfall case. The values of the cloud variables are larger and the interactions between the microphysical processes and the thermal and dynamic processes of Liaoning snowfall case are stronger than those of Beijing snowfall case.