Precursory specialties of apparent stresses in Yunnan earthquake series

On the basis of the assumption that ω^2 model accords with source displacement spectra, we have obtained the mathematical expressions for calculating apparent stresses of moderate-small shocks from low-frequency flat level and comer frequency. By using digital seismic records, apparent stress values are calculated for 823 moderate-small shocks of 4 earthquake series in Yunnan area following corrections for instrument response, propagation influence and site effect. The results show that for the 4 earthquake series in Yunnan area, apparent stress hints precursory information, which means that if a moderate-small shock occurs with apparent stress larger than 1 MPa in an earthquake series, a moderate-strong earthquake will occur afterwards; and if there is not moderate-small shock with apparent stress larger than 1 MPa after a moderate-strong event in an earthquake series, strong aftershock will not occur. The research also indicates that the average apparent stress value is 0.8 MPa in Yunnan area, therefore, apparent stress is not obviously related to seismic magnitude.

Retrieval of Outgoing Longwave Radiation from COMS Narrowband Infrared Imagery

Hourly outgoing longwave radiation （OLR） from the geostationary satellite Communication Oceanography Meteorological Satellite （COMS） has been retrieved since June 2010.The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels.This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm （OLR12.0 using the 12.0 μm channel） and three multiple-channel algorithms （OLR10.8＋12.0 using the 10.8 and 12.0 pm channels; OLR6.7＋10.8 using the 6.7 and 10.8 μm channels; and OLRAll using the 6.7,10.8,and 12.0 μm channels）.The COMS OLRs from these algorithms were validated with direct measurements of OLR from a broadband radiometer of the Clouds and Earth＇s Radiant Energy System （CERES） over the full COMS field of view [roughly （50°S-50°N,70°-170°E）] during April 2011.Validation results show that the root-mean-square errors of COMS OLRs are 5-7 W m-2,which indicates good agreement with CERES OLR over the vast domain.OLR6.7＋10.8 and OLRAll have much smaller errors （～ 6 W m-2） than OLR12.0 and OLR10.8＋12.0 （～ 8 W m-2）.Moreover,the small errors of OLR6.7＋10.8 and OLRAll are systematic and can be readily reduced through additional mean bias correction and/or radiance calibration.These results indicate a noteworthy role of the 6.7 μm water vapor absorption channel in improving the accuracy of the OLRs.The dependence of the accuracy of COMS OLRs on various surface,atmospheric,and observational conditions is also discussed.

Thermal based functional evaluation of urban park vegetation

An evaluation of the urban park vegetation was conducted by integrating airborne multispectral scanning system ( MSS ) thermal band data with meteorological. MSS data acquired in the morning and afternoon were utilized to assess the radiant energy budget of different ground cover types and its relationship with the surface types. The spatial distribution of surface temperature ( Ts ) and surface albedo ( A ) varied between different surfaces. However, the spatial variability of net radiation ( Rn ) was reduced by negative feedback of A Ts relationship. The Normalized Difference Vegetation Index ( NDVI ) had a negative correlation with Ts but positively correlated to Rn of the different surface types. Thermal response number ( TRN ), which expresses the dissipative behavior of radiant energy, correctly characterized each ground cover type according to the validated surface property. Forested and lawn covered sites had the highest TRN values consistent with their tendency to resist microclimatic change. The approach shows that by utilizing the MSS thermal signatures, we can relate the microenvironment processes to the biophysical character of each site offering an opportunity to diagnose site specific problems. The approach is proposed as a direct and easily adaptable method for monitoring the urban green park areas and for making objective decisions about their management.

Accurate Shortwave Radiation Simulation with a Two-Layer Aerosol Model in Xinjiang Region

To harness the rich solar energy resources in Xinjiang Region of Northwest China,this study tries to address the issue of lack of downward surface shortwave radiation(DSSR)observations and the need to improve the accuracy of satellite retrieval and numerical simulation of DSSR under varied sky and meteorological conditions.(1)A two-layer aerosol model specific to Xinjiang was developed to capture the vertical distributions of aerosols based on multiple data sources including lidar,GPS sounding,ground meteorological observations,and profiles from the ECMWF reanalysis version 5(ERA5)data.The results show that the ERA5/PBLH(planetary boundary layer height)and ERA5/ALH(aerosol layer height)could be used to establish the two-layer aerosol model and characterize the vertical distribution of aerosols in Xinjiang Region.(2)Using the Santa Barbara Discrete Atmospheric Radiative Transfer(SBDART)model,a localized inverse model of clear-sky DSSR was established.After parameter adjustment and using the optimal combination of input parameters for DSSR simulation together with the two-layer aerosol model,the model-simulated DSSR(DSSRSBD)under clear-sky conditions improved significantly compared to the initial results,with all fitting indices greatly improved.(3)In addition,the study demonstrated that the impact of the two-layer aerosol model on DSSR was more pronounced under dust conditions than clear-sky conditions.(4)Using the localized clear-sky DSSR inversion model and its required parameters,simulations were also conducted to capture the spatiotemporal distribution of DSSR under clear-sky conditions in Xinjiang from 2017 to 2019.The annual average DSSR_(SBD)under clear-sky conditions in Xinjiang during 2017–2019 was 606.78 W m^(-2),while DSSR from CERES(DSSR_(CER))under the same conditions was generally higher(703.95 W m^(-2)).(5)It is found that satellite remote sensing products experienced data loss in high-altitude snow areas,where numerical simulation technology could serve as a valuable complement.

Evaluation of Reprocessed Fengyun-3B Global Outgoing Longwave Radiation Data:Comparison with CERES OLR

Outgoing longwave radiation(OLR)at the top of the atmosphere(TOA)is a key parameter for understanding and interpreting the relationship between clouds,radiation,and climate interactions.It has been one of the operational products of the Fengyun(FY)meteorological satellites.OLR accuracy has gradually improved with advancements in satellite payload performance and the OLR retrieval algorithm.Supported by the National Key R&D Program Retrospective Calibration of Historical Chinese Earth Observation Satellite data(Richceos)project,a long-term OLR climate data record(CDR)was reprocessed based on the recalibrated Level 1 data of FY series satellites using the latest OLR retrieval algorithm.In this study,Fengyun-3B(FY-3B)’s reprocessed global OLR data from 2010 to 2018 were evaluated by using the Clouds and the Earth’s Radiant Energy System(CERES)global daily OLR data.The results showed that there was a high consistency between the FY-3B instantaneous OLR and CERES Single Scanner Footprint(SSF)OLR.Globally,between the two CDR datasets,the correlation coefficient reached 0.98,and the rootmean-square error(RMSE)was approximately 8-9 W m^(−2).The bias mainly came from the edge regions of the satellite orbit,which may be related to the satellite zenith angle and cloud cover distribution.It was shown that the longterm FY-3B OLR had temporal stability compared to CERES OLR long-term data.In terms of spatial distribution,the mean deviations showed zonal and seasonal characteristics,although seasonal fluctuations were observed in the differences between the two datasets.Effects of FY-3B OLR application to the South China Sea monsoon region and ENSO were demonstrated and analyzed,and the results showed that the seasonal deviation of FY-3B’s OLR comes mainly from the retrieval algorithm.However,it has little effect on the analysis of climate events.