Radiometric calibration is a procedure to obtain at-sensor radiance from digital number records. Accurately calibrated radiation is critical in retrieving brightness temperatureand Land Surface Temperature（LST）. Uncertainty in radiometric calibration typically becomes increasingly obvious because of the decay of the sensor during in-orbit operation. In practice, radiometriccalibration is determined by calibration parameters. In this study, radiometric calibration of the HJ-1B thermal channel and the effects of calibration uncertainty on LST retrieval are investigated.A sensitivity model based on the radiative transfer model is proposed to assess the effects of radiometric calibration on LST retrieval.The calibration parameters for HJ-1B imagery are not updated in a timely manner（always annually）; this lack of timeliness inevitably results in errors in radiometric calibration. Therefore, two methods are proposed for two specific cases to estimate radiation properly. These two methods are linear interpolation and linear extrapolation.The sensitivity model shows that in terms of the numerical value, the ratio of radiometric calibration deviation to the LST error is approximately 1:11. Under a moderate condition, a 0.1（W·m–2·sr–1·μm–1） uncertainty in radiometric calibration may result in an error of 1.1 K in the final LST result. Simulations based on the calibration parameters of the HJ-1B thermal channel are conducted. The errors in radiometric calibration result from the improper selection of calibration parameters. Generally, even the calibration differences between two neighboring years are considered. The mean absolute errors of LST that approximate 1.0—2.0 K and highly significant LST errors（larger than 5.0K） could be obtained under poor conditions. Case studies show that the calibration parameters in the header file of the HJ-1B imagery are always the parameters updated in the previous year or even two years ago. The calibration parameters for the HJ-1B thermal channel have not been updated since 2012. Thus, two estimation methods based on linear models are proposed to obtain radiometric calibration properly. A case study illustrates that under the current situation, the proposed estimation methods are simple but effective. Therefore, they are recommended to general users as references and for application.The calibration parameters in the header file of the HJ-1B imagery are always not updated timely and frequently. Thus, uncertainty in the radiometric calibration of the HJ-1B thermal channel is inevitable. The LST errors resulting from radiometric calibration uncertainty are influenced by several factors, including surface characteristics（i.e., temperature and emissivity） and atmospheric conditions. The actual effects depend on seasonal and regional variations, which emphasize the challenge of accurately obtaining LST from the HJ-1B thermal channel. Two methods are proposed and assessed for the radiometric calibration of the HJ-1B thermal channel. Although the estimation methods are generally acceptable because of their simplicity and effectiveness, additional efforts are required to clarify the actual performance of the sensor. General users should consider radiometric calibration uncertainty in quantitative applications of the HJ-1B thermal imagery.

radiometric calibration;thermal remote sensing;land surface temperature;sensitivity;HJ-1B