A high-quality hourly, daily and monthly solar irradiance dataset in China during 1981-2014 based on MERRA-2 Reanalysis products

<b>A high-quality hourly, daily and monthly solar irradiance dataset in China during 1981-2014</b><b> based on MERRA-2 Reanalysis products</b>Wenmin Qin¹, Lunche Wang¹, Ming Zhang¹, Lan Feng¹, Yulong Zhong¹, Qiqi Zhu¹，Hejin Fang¹, Hong Cai¹, Chao Yang²¹Hubei Key Laboratory of Critical Zone Evolution, School of Geography and Information Engineering, China University of Geosciences, Wuhan 430074, China;² Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;Corresponding author: Wenmin Qin, Hubei Key Laboratory of Critical Zone Evolution, School of Geography and Information Engineering, China University of Geosciences, Lumo road 388, Hongshan District, Wuhan 430074, China; Tel.: [phone]; E-mail: [e-mail].<b>Abstract: </b>Solar irradiance (SI) is the main driving factor contributing to climate change and energy balance between the land and atmosphere. High-quality records of global solar irradiance (GHI), direct normal irradiance (DNI) and diffuse solar irradiance (DIF) are of vital importance for solar applications, but the solar radiation observations are sparse around the world. As an alternative, numerous SI reanalysis data in grid format have been developed in regional and global scales. Among them, the MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2) products could provide high quality SI records with acceptable accuracy and long temporal ranges. This study attempted to improve the accuracy of GHI records derived from MERRA-2 products, and to generate grid DNI and DIF datasets for all-sky conditions over mainland China during 1981-2014, based on the REST2 model and cloud transmittance estimates combining sunshine observations. The results indicate that the estimated GHI values (GHInew) show higher agreements with GHI measurement at 17 CMA (China meteorological administrations) stations than that for the GHI records derived from MERRA-2 products (MERRA-2 GHI). Then, grid GHI, DNI and DIF datasets (0.50° (lat) *0.625° (lon)) throughout China were constructed. The results indicated that the MERRA-2 GHI records may overestimate the GHI values over mainland China. The grid GHI, DNI and DIF dataset generated in this study can assist in numerous solar studies and applications.<br><br><br>Correspondence to: qin wenmin ([e-mail])

1981-2014年中国区域基于MERRA-2再分析产品的高质量逐时、逐日及逐月太阳辐照度数据集

秦文敏¹，王伦澈¹，张明¹，冯兰¹，钟玉龙¹，朱琪琪¹，方和进¹，蔡宏¹，杨超²

¹中国地质大学（武汉）地理与信息工程学院，关键带演化湖北省重点实验室，武汉 430074，中国；²中国科学院测量与地球物理研究所，武汉 430077，中国；

通讯作者：秦文敏，中国地质大学（武汉）地理与信息工程学院关键带演化湖北省重点实验室，武汉市洪山区鲁磨路388号，430074，中国；电话：[phone]；电子邮箱：[e-mail].

**摘要：** 太阳辐照度（Solar Irradiance, SI）是驱动气候变化、维持陆-气能量平衡的核心因子。全球水平辐照度（Global Horizontal Irradiance, GHI）、直接法向辐照度（Direct Normal Irradiance, DNI）与散射太阳辐照度（Diffuse Solar Irradiance, DIF）的高质量观测记录对太阳能利用具有至关重要的意义，但全球范围内的太阳辐射观测站点分布极为稀疏。作为替代方案，学界已在区域及全球尺度开发了诸多格点形式的太阳辐照度再分析数据。其中，MERRA-2（Modern-Era Retrospective Analysis for Research and Applications, 版本2）产品可提供精度可靠、时间跨度较长的高质量太阳辐照度记录。本研究基于REST2模型与结合日照观测的云透射率估算方法，旨在提升MERRA-2产品衍生的全球水平辐照度记录精度，并生成1981-2014年中国全域全天空条件下的格点直接法向辐照度与散射太阳辐照度数据集。结果显示，相较于MERRA-2产品衍生的全球水平辐照度记录（MERRA-2 GHI），本研究估算的全球水平辐照度（GHI_new）与中国气象局（China Meteorological Administrations, CMA）17个站点的实测全球水平辐照度吻合度更高。随后，本研究构建了覆盖全国的格点全球水平辐照度、直接法向辐照度与散射太阳辐照度数据集（0.50°（纬度）×0.625°（经度））。结果表明，MERRA-2全球水平辐照度记录对中国全域的全球水平辐照度存在高估现象。本研究生成的格点全球水平辐照度、直接法向辐照度与散射太阳辐照度数据集可助力各类太阳能相关研究与应用。

通讯作者：秦文敏（[e-mail]）