Near-infrared thermal emissivity from ground based atmospheric dust measurements at ORM

TL;DR

This study analyzes atmospheric dust at ORM using particle counters and estimates its impact on near-infrared sky brightness, finding dust contribution is generally minor but varies seasonally.

Contribution

It introduces a method to estimate aerosol emissivity's effect on NIR sky brightness from ground-based measurements.

Findings

Dust levels are higher in Spring than Summer.

Dust contributes up to 10% of NIR sky brightness during dusty days.

Dust emission impact on NIR background is generally negligible.

Abstract

We present an analysis of the atmospheric content of aerosols measured at Observatorio del Roque de los Muchachos (ORM; Canary Islands). Using a laser diode particle counter located at the Telescopio Nazionale Galileo (TNG) we have detected particles of 0.3, 0.5, 1.0, 3.0, 5.0 and 10.0 um size. The seasonal behavior of the dust content in the atmosphere is calculated. The Spring has been found to be dustier than the Summer, but dusty conditions may also occur in Winter. A method to estimate the contribution of the aerosols emissivity to the sky brightness in the near-infrared (NIR) is presented. The contribution of dust emission to the sky background in the NIR has been found to be negligible comparable to the airglow, with a maximum contribution of about 8-10% in the Ks band in the dusty days.