This paper describes a new radiation scheme ecRad for use both in the model of the European Centre for Medium‐Range Weather Forecasts (ECMWF), and off‐line for noncommercial research. Its modular structure allows the spectral resolution, the description of cloud and aerosol optical properties, and the solver, to be changed independently. The available solvers include the Monte Carlo Independent Column Approximation (McICA), Tripleclouds, and the Speedy Algorithm for Radiative Transfer through Cloud Sides (SPARTACUS), the latter which makes ECMWF the first global model capable of representing the 3‐D radiative effects of clouds. The new implementation of the operational McICA solver produces less noise in atmospheric heating rates, and is 41% faster, which can yield indirect forecast skill improvements via calling the radiation scheme more frequently. We demonstrate how longwave scattering may be implemented for clouds but not aerosols, which is only 4% more computationally costly overall than neglecting longwave scattering and yields further modest forecast improvements. It is also shown how a sequence of radiation changes in the last few years has led to a substantial reduction in stratospheric temperature biases.

中文翻译：

---

ECMWF模型的灵活高效的辐射方案

本文介绍了一种新的辐射方案ecRad，该方案既可用于欧洲中型天气预报中心（ECMWF）的模型，也可用于非商业研究的离线模型。它的模块化结构允许独立更改光谱分辨率，云和气溶胶光学特性的描述以及求解器。可用的求解器包括蒙特卡洛独立列近似（McICA），三重云，以及通过云侧进行辐射传递的快速算法（SPARTACUS），后者使ECMWF成为第一个能够表示云的3D辐射效应的全局模型。可操作的McICA求解器的新实现在大气加热速率中产生的噪声较小，并且速度提高了41％，这可以通过更频繁地调用辐射方案来间接提高预测技能。我们演示了如何对云实施长波散射，而不是对气溶胶实施长波散射，与忽略长波散射相比，这在总体上仅比忽略长波散射高4％的计算成本，并产生了适度的预报改进。还显示了最近几年中辐射序列的变化如何导致平流层温度偏差的显着降低。