WCRP and WWRP THORPEX YOTC (Year of Tropical Convection) Project, Single Parameter 6-Hourly Pressure Level Forecast Time Series, Transformed to a Regular 1600 by 800 (N400) Gaussian Grid

The realistic representation of tropical convection in our global atmospheric models is a long-standing grand challenge for numerical weather forecasts and global climate predictions. Our lack of fundamental knowledge and practical capabilities in this area leaves us disadvantaged in modeling and predicting prominent phenomena of the tropical atmosphere such as the ITCZ, ENSO, TBO, monsoons and their active or break periods, the MJO, subtropical stratus decks, near-surface ocean properties, easterly waves, tropical cyclones, bulk budgets of cloud microphysical quantities, and even the diurnal cycle. Furthermore, tropical weather and climate disturbances strongly influence stratospheric-tropospheric exchange as well as the extratropics, with the later mediated via poleward migration of synoptic systems or through initiating Rossby wave trains that can involve a range of processes and time scales.

To address the challenge of tropical convection, WCRP and WWRP/THORPEX propose a Year of coordinated observing, modeling and forecasting of organized tropical convection and its influences on predictability as a contribution to the United Nations Year of Planet Earth to complement the International Polar Year (IPY). This effort is intended to exploit the vast amounts of existing and emerging observations, the expanding computational resources and the development of new, high-resolution modeling frameworks, with the objective of advancing the characterization, diagnosis, modeling, parameterization and prediction of multiscale convective and dynamic interactions, including the two-way interaction between tropical and extra-tropical weather or climate. This activity and its ultimate success will be based on the coordination of a wide range of ongoing and planned international programmatic activities (e.g., GEWEX/CEOP/GCSS, AMY, EOS, GOOS), strong collaboration among the operational prediction, research laboratory and academic communities, and the construction of a comprehensive data base consisting of satellite data, in-situ data sets and global, high-resolution forecast and simulation model outputs relevant to tropical convection. The proposed timing, focus year approach and integrated framework of this effort is intended to leverage the most benefit from recent investments in Earth Science infrastructure as well as entrain a new generation of young scientists into tackling the outstanding problems in the field of weather and climate prediction.

It is recommended that potential users of YOTC peruse the Related RDA Datasets ds629.1-ds629.6 (please see below) which represent transformed versions of the raw ECMWF YOTC archive (ds629.0) by the Data Support Section. The transformed versions are archived on an N400 1600 by 800 regular Gaussian grid, starting from high resolution reduced Gaussian grids and spectral coefficients. In addition, horizontal winds have been added and computed from spectral vorticity and divergence.

在我国的全球大气模型中，热带对流的真实表征一直是数值天气预报和全球气候预测领域的一项长期重大挑战。我们在这一领域的根本知识和实践能力不足，导致我们在模拟和预测热带大气中的显著现象（如赤道辐合带、厄尔尼诺南方涛动、热带波动、季风及其活跃或中断期、季风振荡、副热带层积云层、近海表面海洋特性、东风波、热带气旋、云微物理量的大气收支以及昼夜更替等）时处于不利地位。此外，热带天气和气候扰动对平流层-对流层交换以及中纬度地区产生了强烈影响，后者通过天气系统的极地向迁移或通过引发罗斯贝波列而实现，这些波列涉及多种过程和时间尺度。

为应对热带对流的挑战，世界气候研究计划（WCRP）和世界气象研究计划/THORPEX提出了一项协调观测、模拟和预测有组织热带对流及其对可预测性影响的计划，作为联合国地球年（UN Year of Planet Earth）的贡献，以补充国际极地年（IPY）。这一努力旨在充分利用现有和新兴的观测数据、不断扩大的计算资源以及新开发的、高分辨率建模框架的发展，目标是推进多尺度对流和动力学相互作用的表征、诊断、建模、参数化和预测，包括热带与中纬度天气或气候之间的双向相互作用。这一活动和其最终成功将基于广泛进行中的和计划中的国际项目（例如，GEWEX/CEOP/GCSS、AMY、EOS、GOOS）的协调、操作预测、研究实验室和学术界之间的紧密合作，以及构建一个包含卫星数据、地面数据集以及与热带对流相关的全球、高分辨率预报和模拟模型输出的综合性数据库。这一努力的拟议时间、重点年份方法和综合框架旨在最大限度地发挥对地球科学基础设施最近投资的效益，并吸引新一代年轻科学家投身于解决天气和气候预测领域的突出问题。

建议YOTC的潜在用户查阅相关的RDA数据集ds629.1-ds629.6（请参见下文），这些数据集代表了数据支持部门对原始ECMWF YOTC存档（ds629.0）的转换版本。转换版本存档在N400 1600×800的规则高斯网格上，从高分辨率缩减高斯网格和谱系数开始。此外，已添加并计算了水平风，其由谱涡度和散度得出。