Optical Turbulence Characterization at LAMOST Site: Observations and Models

TL;DR

This study characterizes atmospheric optical turbulence at the LAMOST site using measurements and models, providing key parameters for high-resolution astronomy and comparing results with other observatories.

Contribution

It combines observational data with WRF model predictions to comprehensively assess optical turbulence parameters at LAMOST, a novel integrated approach.

Findings

Median seeing around 1.07 arcsec across methods

Vertical turbulence profiles obtained with SSS

Model predictions closely match observational measurements

Abstract

Atmospheric optical turbulence seriously limits the performance of high angular resolution instruments. An 8-night campaign of measurements was carried out at the LAMOST site in 2011, to characterize the optical turbulence. Two instruments were set up during the campaign: a Differential Image Motion Monitor (DIMM) used to measure the total atmospheric seeing, and a Single Star Scidar (SSS) to measure the vertical profiles of the turbulence C_n^2(h) and the horizontal wind velocity V(h). The optical turbulence parameters are also calculated with the Weather Research and Forecasting (WRF) model coupled with the Trinquet-Vernin model, which describes optical effects of atmospheric turbulence by using the local meteorological parameters. This paper presents assessment of the optical parameters involved in high angular resolution astronomy. Its includes seeing, isoplanatic angle, coherence time, coherence etendue, vertical profiles of optical turbulence intensity _n^2(h)$ and horizontal wind speed V(h). The median seeing is respectively 1.01 arcsec, 1.17 arcsec and 1.07arcsec as measured with the DIMM, the SSS and predicted with WRF model. The history of seeing measurements at the LAMOST site are reviewed, and the turbulence measurements in this campaign are compared with other astronomical observatories in the world.