Characterising the properties of the atmospheric emission at Teide Observatory in the 10-20 GHz range with QUIJOTE data

TL;DR

This study characterizes atmospheric emission properties at Teide Observatory in the 10-20 GHz range using QUIJOTE data, improving atmospheric models and turbulence understanding for CMB research.

Contribution

It provides empirical atmospheric profiles and turbulence analysis at Teide Observatory, supporting future CMB experiments and atmospheric physics studies.

Findings

Water vapour density follows exponential decay with 1000 m half-height.

Median PWV is 3.3 mm during 2012-2018.

Atmospheric conditions are stable for 1-2 hours.

Abstract

QUIJOTE is a CMB experiment composed of two telescopes, QT1 and QT2, located at the Teide Observatory in Tenerife, Spain. The MFI instrument (2012-2018), installed on QT1, observed the sky at four frequency bands (11, 13, 17, and 19 GHz) with one degree angular resolution. Its successor, MFI2, began operations in 2024 and operates in the same bands. This paper has two main goals: first, to characterise the atmospheric conditions at Teide Observatory to improve existing models at these frequencies, and second, to empirically characterise atmospheric turbulence using QUIJOTE MFI and MFI2 observations. This work has implications for both atmospheric physics and CMB studies and can support future reanalyses of MFI data or the preparation of upcoming instruments such as the Tenerife Microwave Spectrometer. We used data from GPS antennas, the STELLA observatory, and radio soundings to derive median profiles and distributions of key atmospheric parameters for 2012-2018. MFI data were analysed to compute atmospheric structure functions at 17 and 19 GHz and to study the correlation properties of the atmospheric signal through cross-correlation between horns at the same frequency. MFI2 observations were used to estimate the atmospheric power spectrum and compare it with the structure function derived from MFI data. The water vapour density profile follows an exponential decay with a characteristic half-height of about 1000 m. Median PWV in 2012-2018 is 3.3 mm. For high PWV conditions, the structure function agrees with the Kolmogorov turbulence model. The slope of the power spectrum also matches the model prediction, within the frequency range limited by the outer scale and instrument noise. Finally, from the correlation function, we find that atmospheric conditions remain stable for about 1-2 hours.