Using microwave brightness temperature diurnal cycle to improve emissivity retrievals over land

► Using Ts in emissivity retrieval leads to large differences between day and night. ► We construct diurnal cycle of microwave brightness temperature. ► A PCA approach shows the spatial variation of TB diurnal cycle. ► Effective temperature is generated by adjusting TS based on diurnal cycle of TB. ► The proposed Teff anomalies reduce day-night emissivity differences.