Validation of Atmospheric Absorption Models within the 20–60 GHz Band by Simultaneous Radiosonde and Microwave Observations: The Advantage of Using ECS Formalism

Abstract

The precise calculation of atmospheric absorption in a microwave band is highly important for atmospheric remote-sensing with ground-based and satellite-borne radiometers, as it is a key element in procedures for temperature, humidity or trace gas concentration retrieval. The accuracy of the absorption model directly affects the accuracy of the retrieved information and reliability of the resulting forecasts. In this study, we analyze the difference between observed and simulated microwave spectra obtained from more than four years of microwave and radiosonde observations over Nizhny Novgorod (56.2°N, 44°E). We focus on zenith-measured microwave data in the 20–60 GHz frequency range in clear-sky conditions. The use of a conventional absorption model in simulations leads to a significant difference in frequency channels within the 51–54 GHz range, while calculations employing a more accurate model based on the Energy Corrected Sudden (ECS) formalism for molecular oxygen absorption reduces the difference several-fold.

The Non-Thermal Radio Emissions of the Solar Transition Region and the Proposal of an Observational Regime

“…However, we still plan to install a temperature-controlling system in the receiving system to minimize the impact of environmental temperature changes on observations. Additionally, we will also consider the corrections of atmospheric absorption by using an atmospheric absorption model [57][58][59]. Table 3 lists the main parameters of the test-SUBMS.…”

“…Using the Y factor method with T hot from noise input and T cold from cold sky Atmospheric Absorption correction Using an atmospheric absorption model [58,59] The calibration of both the space-based SUBMS and the ground-based test-SUMBS will be carried out by using the relative calibrating method [57], and the reference source will be the cold sky and a known constant noise source.…”

A Microwave Radiometer Residual Inversion Neural Network Based on a Deadband Conditioning Model

“…k a is the sum of oxygen and water vapor absorption coefficients, in the formula T B (0) denotes the brightness temperature of all microwave radiation over the surface, r denotes the altitude, T(r) denotes the atmospheric temperature at altitude τ(0,r) denotes the optical thickness from altitude r to the ground. The first term on the right indicates the data after the attenuation of the cosmic background radiation brightness temperature, and the second term indicates the cumulative sum of all the thin atmospheric layers of microwave radiation brightness temperature above the Earth's surface reaching the Earth's surface after the attenuation [14].…”