Ground-Based Microwave Radiometer Calibration: an Overview

ABSTRACT This paper intends to briefly present some basic concepts on the microwave radiometry and radiometer calibration research in remote sensing applications and demonstrate results and analysis of the cryogenic calibration of a microwave ground-based radiometer currently deployed in scientific campaigns in Brazil. The equipment described in this text operates at 22 - 30 GHz and at 51 - 59 GHz frequency ranges and uses as the calibration standard a target cooled by liquid nitrogen. Since an accurate calibration (with observation errors below 0.5 K) is important to provide confidence in the retrieval of vertical temperature and humidity profiles, this work aims also to comment on some effects of the errors in calibration procedure on the atmospheric parameters of interest.

摘要 本文简要介绍了遥感应用中微波辐射测量（microwave radiometry）与辐射计定标（radiometer calibration）研究的基本概念，并展示了当前部署于巴西科学考察任务中的地面微波辐射计（microwave ground-based radiometer）的低温定标（cryogenic calibration）结果与分析。本文所述设备工作于22~30 GHz与51~59 GHz两个频段，采用液氮冷却的定标靶标作为定标标准。鉴于精准定标（观测误差低于0.5 K）可为大气垂直温度与湿度廓线的反演提供可靠性保障，本文还探讨了定标流程中的误差对所关注大气参数的若干影响。