No abstract

Radio occultation (RO) is a powerful tool for remotely sensing the atmosphere, producing globally distributed soundings with high vertical resolution and high temperature retrieval accuracy, especially in the stratosphere. The spatial distribution of the soundings typically prevents the use of these measurements for studying atmospheric effects with small horizontal or temporal scales. However, careful arrangement of a dedicated RO constellation can yield sounding clusters useful for the tomographic reconstruction of internal gravity waves with horizontal wavelengths in the tens of kilometers. This paper presents occultation cluster quality metrics predictive of internal gravity wave tomographic reconstruction error and uses these metrics to compare the performance of two alternative RO constellation geometries, mutual orbit groups (MOG) and a spread in right ascension of the ascending node (RAAN). MOG constellations have better overall performance and yield more consistent cluster quality across all sampled latitudes, while RAAN-spread constellations have improved equatorial quality and a trend toward reduced quality at the edges of the latitude range. Additionally, analysis of clusters by latitude, ray azimuth, and quality is performed in order to examine the trends in the outlier best-and worst-performing clusters for each constellation type.

The Micro-Sized Microwave Atmospheric Satellite (MicroMAS-2A) is a 3U CubeSat that launched in January 2018 as a technology demonstration for future microwave sounding constellation missions, such as the NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission now in development. MicroMAS-2A has a miniaturized 1U 10-channel passive microwave radiometer with channels near 90, 118, 183, and 206 GHz for moisture and temperature profiling and precipitation imaging [4]. MicroMAS-2A provided the first CubeSat atmospheric vertical sounding data from orbit and to date is the only CubeSat to provide temperature and moisture sounding and surface imaging. In this paper, we analyze six segments of data collected from MicroMAS-2A in April 2018 and compare them to ERA5 reanalysis fields coupled with the Community Radiative Transfer Model (CRTM). This initial assessment of CubeSat radiometric accuracy shows biases relative to ERA5 with magnitudes ranging from 0.4 to 2.2 K (with standard deviations ranging from 0.7 to 1.2 K) for the four mid-tropospheric temperature channels and biases of 2.2 and 2.8 K (standard deviations 1.8 and 2.6 K) for the two lower tropospheric water vapor channels.