论文标题

高精度的短期PWV操作预测在VLT和天空背景的视角

High accuracy short-term PWV operational forecast at the VLT and perspectives for sky background forecast

论文作者

Turchi, A., Masciadri, E., Pathak, P., Kasper, M.

论文摘要

在本文中,我们介绍了有史以来通过将自回归(AR)技术应用于可沉淀的水蒸气(PWV)获得的第一个结果。该研究是在非常大的望远镜上进行的。最近已提出该AR技术在短时间(长达几个小时)的大气和星形气候参数中提供预测,通过在下午早些时候提供的“标准预测”方面取得更好的表现。 AR方法使用感兴趣参数的实时测量值来改善使用大气模型进行的预测。我们在这里使用了LHATPRO提供的测量值,LHATPRO是一种辐射计,可连续测量VLT处的PWV。在将1H的AR预测与标准预测进行比较时,我们观察到$ \ sim $ 8(即$ \ sim $ 800%)的增益系数在预测准确性方面。在PWV $ \ LEQ $ 1毫米范围内,这对于红外天文应用至关重要,预测的RMSE仅为几百毫米(0.04毫米)的顺序。因此,我们证明了AR技术为对PWV敏感的所有工具提供了VLT科学运营的重要好处。此外,我们展示了预测PWV的这种能力如何也可以预测红外范围的天空背景(对METIS极为吸引人)。我们通过将这种方法应用于ESO和突破性计划支持的近项目(Alpha CEN地区的新地球)来量化这种能力。

In this paper we present the first results ever obtained by applying the autoregressive (AR) technique to the precipitable water vapour (PWV). The study is performed at the Very Large Telescope. The AR technique has been recently proposed to provide forecasts of atmospheric and astroclimatic parameters at short time scales (up to a few hours) by achieving much better performances with respect to the 'standard forecasts' provided early afternoon for the coming night. The AR method uses the real-time measurements of the parameter of interest to improve the forecasts performed with atmospherical models. We used here measurements provided by LHATPRO, a radiometer measuring continuously the PWV at the VLT. When comparing the AR forecast at 1h to the standard forecast, we observe a gain factor of $\sim$ 8 (i.e. $\sim$ 800 per cent) in terms of forecast accuracy. In the PWV $\leq$ 1 mm range, which is extremely critical for infrared astronomical applications, the RMSE of the predictions is of the order of just a few hundredth of millimetres (0.04 mm). We proved therefore that the AR technique provides an important benefit to VLT science operations for all the instruments sensitive to the PWV. Besides, we show how such an ability in predicting the PWV can be useful also to predict the sky background in the infrared range (extremely appealing for METIS). We quantify such an ability by applying this method to the NEAR project (New Earth in the Alpha Cen region) supported by ESO and Breakthrough Initiatives.

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