Simple method to estimate the optical turbulence over snow and ice

Monthly Notices of the Royal Astronomical Society

Wang

et al. 2022

In Antarctica, excellent astronomical observing conditions have been measured at Dome A during nighttime (or polar winter). This study investigates the performance of the Polar-optimized version of the Weather Research and Forecasting (Polar WRF, PWRF hereafter) for simulating the night-time astronomical seeing at Dome A. The seeing values were estimated by a seeing model, which used the PWRF-simulated wind speed and temperature as inputs. And three methods to obtain the boundary layer height in the seeing model have been examined. The estimated seeing agrees well with 50-day measurements from the KunLun Differential Image Motion Monitor at Dome A during the nighttime of 2019; the correlation coefficients range from 0.62 to 0.71. The PWRF-simulated meteorological parameters indicate that, low wind speed and strong temperature inversion (when a large gradient Richardson number always occurs) near the ground can lead to good seeing condition. The results suggest that the PWRF model could be a reliable tool for scheduling observational astronomy at Dome A during nighttime.

Simulating the night-time astronomical seeing at Dome A using Polar WRF

Monthly Notices of the Royal Astronomical Society

Wang

et al. 2022

Model for estimating the astronomical seeing at Dome A, Antarctica

Han

et al. 2021

Opt. Express

A model for estimating astronomical seeing at Kunlun Station (Dome A, Antarctica) is proposed. This model is based on the Tatarskii equation, using the wind shear and temperature gradient as inputs, and a seeing model depending directly on the weather data is provided. The seeing and near-ground weather data to build and validate the proposed seeing model were measured at Dome A during the summer of 2019. Two calculation methods were tested from the measured weather data relating the wind shear and temperature gradient to a combination of the two levels for the boundary layer. Both methods performed well, with correlation coefficients higher than 0.77. The model can capture the main seeing trends in which the seeing becomes small when weak wind speed and strong temperature inversion occur inside the boundary layer.

Estimating the astronomical seeing above Dome A using Polar WRF based on the Tatarskii equation

Han

et al. 2021

Opt. Express

A seeing model based on the Tatarskii equation, which uses wind shear and temperature gradient as inputs, has been proposed for Dome A in our previous study. It has been shown that the seeing was correctly reproduced statistically. In this paper, in order to investigate the ability of the Polar version of the Weather Research and Forecasting (PWRF) model to forecast the seeing, we have tried three different PWRF-simulated wind shear and temperature gradient combinations of two levels for the near-ground. The three combinations all give good performance with the correlation coefficients being higher than 0.75, when compared with the seeing measured by the Kunlun Differential Image Motion Monitor at Dome A during the summer of 2019. Besides this, the gradient Richardson number (Ri), which was also simulated by the PWRF model, basically behaved as expected as the Ri is generally large when the measured seeing is small. These results suggest that the PWRF model can be used to forecast the astronomical seeing above Dome A.