Knowland K E, Keller C A, Wales P A, Wargan K, Coy L, Johnson M S, Liu J, Lucchesi R A, Eastham S D, Fleming E, Liang Q, Leblanc T, Livesey N J, Walker K A, Ott L E, Pawson S
Universities Space Research Association (USRA)/GESTAR Columbia MD USA.
NASA Goddard Space Flight Center (GSFC) Global Modeling and Assimilation Office (GMAO) Greenbelt MD USA.
J Adv Model Earth Syst. 2022 Jun;14(6):e2021MS002852. doi: 10.1029/2021MS002852. Epub 2022 Jun 7.
The NASA Goddard Earth Observing System (GEOS) Composition Forecast (GEOS-CF) provides recent estimates and 5-day forecasts of atmospheric composition to the public in near-real time. To do this, the GEOS Earth system model is coupled with the GEOS-Chem tropospheric-stratospheric unified chemistry extension (UCX) to represent composition from the surface to the top of the GEOS atmosphere (0.01 hPa). The GEOS-CF system is described, including updates made to the GEOS-Chem UCX mechanism within GEOS-CF for improved representation of stratospheric chemistry. Comparisons are made against balloon, lidar, and satellite observations for stratospheric composition, including measurements of ozone (O) and important nitrogen and chlorine species related to stratospheric O recovery. The GEOS-CF nudges the stratospheric O toward the GEOS Forward Processing (GEOS FP) assimilated O product; as a result the stratospheric O in the GEOS-CF historical estimate agrees well with observations. During abnormal dynamical and chemical environments such as the 2020 polar vortexes, the GEOS-CF O forecasts are more realistic than GEOS FP O forecasts because of the inclusion of the complex GEOS-Chem UCX stratospheric chemistry. Overall, the spatial patterns of the GEOS-CF simulated concentrations of stratospheric composition agree well with satellite observations. However, there are notable biases-such as low NO and HNO in the polar regions and generally low HCl throughout the stratosphere-and future improvements to the chemistry mechanism and emissions are discussed. GEOS-CF is a new tool for the research community and instrument teams observing trace gases in the stratosphere and troposphere, providing near-real-time three-dimensional gridded information on atmospheric composition.
美国国家航空航天局戈达德地球观测系统（GEOS）成分预报（GEOS-CF）近乎实时地向公众提供大气成分的近期估算值和5天预报。为此，GEOS地球系统模型与GEOS-化学对流层-平流层统一化学扩展（UCX）相耦合，以呈现从地表到GEOS大气层顶部（0.01百帕）的成分。描述了GEOS-CF系统，包括对GEOS-CF中GEOS-化学UCX机制所做的更新，以改进对平流层化学的呈现。针对平流层成分，与气球、激光雷达和卫星观测数据进行了比较，包括臭氧（O）以及与平流层O恢复相关的重要氮和氯物种的测量。GEOS-CF将平流层O向GEOS前向处理（GEOS FP）同化的O产品进行调整；因此，GEOS-CF历史估算中的平流层O与观测结果吻合良好。在异常的动力和化学环境（如2020年的极地涡旋）中，由于纳入了复杂的GEOS-化学UCX平流层化学，GEOS-CF的O预报比GEOS FP的O预报更符合实际情况。总体而言，GEOS-CF模拟的平流层成分浓度的空间模式与卫星观测结果吻合良好。然而，存在明显偏差，如极地地区的NO和HNO较低，以及整个平流层的HCl普遍较低，并讨论了未来对化学机制和排放的改进。GEOS-CF是研究界和观测平流层和对流层微量气体的仪器团队的一种新工具，提供关于大气成分的近乎实时的三维网格化信息。
