Evaluation of the Long-term Performance of Microwave Radiation Imager Onboard Chinese Fengyun Satellites

Accurate brightness temperature(BT)is a top priority for retrievals of atmospheric and surface parameters.Microwave Radiation Imagers(MWRIs)on Chinese Fengyun-3(FY-3)serial polar-orbiting satellites have been providing abundant BT data since 2008.Much work has been done to evaluate short-term MWRI observations,but the long-term performance of MWRIs remains unclear.In this study,operational MWRI BTs from 2012–19 were carefully examined by using simultaneous Advanced Microwave Scanning Radiometer 2(AMSR2)BTs as the reference.The BT difference between MWRI/FY3B and AMSR2 during 2012–19 increased gradually over time.As compared with MWRI/FY3B BTs over land,those of MWRI/FY3D were much closer to those of AMSR2.The ascending and descending orbit difference for MWRI/FY3D is also much smaller than that for MWRI/FY3B.These results suggested the improvement of MWRI/FY3D over MWRI/FY3B.A substantial BT difference between AMSR2 and MWRI was found over water,especially at the vertical polarization channels.A similar BT difference was found over polar water based on the simultaneous conical overpassing(SCO)method.Radiative transfer model simulations suggested that the substantial BT differences at the vertical polarization channels of MWRI and AMSR2 over water were partly contributed by their difference in the incident angle;however,the underestimation of the operational MWRI BT over water remained a very important issue.Preliminary assessment of the operational and recalibrated MWRI BT demonstrated that MWRI BTs were substantially improved after the recalibration,including the obvious underestimation of the operational MWRI BT at the vertical polarization channels over water was corrected,and the time-dependent biases were reduced.

Evaluating performance dependency of a geomorphologic instantaneous unit hydrograph-based hydrological model on DEM resolution

The digital elevation model(DEM)is a type of model that has been widely used in terrain analysis and hydrological modeling.DEM resolution influences the hydrological and geomorphologic features of delineated catchments and consequently affects hydrological simulations.This study investigated the impacts of DEM resolution on the performance of the XAJ-GIUH hydrological model,a model coupling the widely used Xinanjiang(XAJ)hydrological model with the geomorphologic instantaneous unit hydrograph(GIUH),in flood simulations in small and medium-sized catchments.To test the model performance,the model parameters were calibrated at a fine DEM resolution(30 m)and then directly transferred to the simulation runs using coarser DEMs.Afterwards,model recalibration was conducted at coarser DEM resolutions.In the simulation runs with the model parameters calibrated at the 30-m resolution,the DEM resolution slightly affected the overall shape of the simulated flood hydrographs but presented a greater impact on the simulated peak discharges in the two study catchments.The XAJ-GIUH model consistently underestimated the peak discharges when the DEM resolution became coarser.The qualified ratio of peak simulations decreased by 35%when the DEM resolution changed from 30 m to 600 m.However,model recalibration produced comparable model per-formances when DEMs with different resolutions were used.This study showed that the impact of DEM resolution on model performance can be mitigated by model recalibration to some extent,if the DEM resolution is not too coarse.

Update on Fengyun Meteorological Satellite Program and Development

China began to develop its meteorological satellite program since 1969.With 50-years’growing,there are 17 Fengyun(FY)meteorological satellites launched successfully.At present,seven of them are in orbit to provide the operational service,including three polar orbiting meteorological satellites and four geostationary meteorological satellites.Since last COSPAR report,no new Fengyun satellite has been launched.The information of the on-orbit FY-2 series,FY-3 series,and FY-4 series has been updated.FY-3D and FY-2H satellites accomplished the commission test and transitioned into operation in 2018.FY-2E satellite completed its service to decommission in 2019.The web-based users and Direct Broadcasting(DB)users keep growing worldwide to require the Fengyun satellite data and products.A new Mobile Application Service has been launched to Fengyun users based on the cloud technology in 2018.In this report,the international and regional co-operations to facilitate the Fengyun user community have been addressed especially.To strengthen the data service in the Belt and Road countries,the Emergency Support Mechanism of Fengyun satellite(FY_ESM)has been established since 2018.Meanwhile,a Recalibrating 30-years’archived Fengyun satellite data project has been founded since 2018.This project targets to generate the Fundamental Climate Data Record(FCDR)as a space agency response to the Global Climate Observation System(GCOS).At last,the future Fengyun program up to 2025 has been introduced as well.

Age Recalibration of the Xiaofeng Dykes, South China, and Its Implications for True Polar Wander at ～820 Ma

Paleomagnetism of the Neoproterozoic Xiaofeng dykes exposed in the Three Gorges region of Hubei Province bear important implications for the paleogeography of the South China block(SCB).New high-precision U-Pb

Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications

TheΛseparation energy forΛhypernuclei,denoted BΛ,measured in 1967,1968,and 1973 are recalibrated using the current best estimates of the mass of particles and nuclei.The recalibrated BΛare systematically larger(except in the case ofΛ~6He)than the originally published values by about 100 keV.The effect of this level of recalibration is very important for light hypemuclei,especially for the hypertriton.The early BΛvalues measured in1967,1968,and 1973 are widely used in theoretical research,and the new results provide better constraints for the conclusions of such studies.