An Analysis of Alternatives for the COSMIC-2 Constellation in the Context of Global Observing System Simulation Experiments

The success of the six-satellite Constellation for Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission in improving global weather forecasts at NOAA motivated the U.S. to develop, in partnership with Taiwan, the follow-on COSMIC-2 mission, a twelve-satellite constellation to be originally deployed in two launches. The first six satellites (COSMIC-2A) at 24-degree inclination are expected to be deployed in late 2018 in a low-inclination orbit for dense equatorial coverage. The second six (COSMIC-2B) were to be deployed at a later time in a high inclination (polar) orbit to provide global coverage. However, the U.S. and Taiwan recently decided to not move forward with the second launch of COSMIC-2. COSMIC-2A is expected to provide ~6,000 RO profiles/day, with better instrument performance than COSMIC, particularly in the tropical latitudes. Most relevant to current operational NWP, RO soundings from COSMIC-2 are expected to penetrate deeper into the lower moist tropical troposphere due to an improved RO receiver and larger antennas with higher signal-to-noise-ratio.

Prior to the decision to not move forward with the launch of the COSMIC-2B receiving satellites, NOAA conducted a series of tradeoff studies in the design and configuration of COSMIC-2B to evaluate possible alternates to the originally proposed polar component of the mission. In particular, the number of RO soundings and their accuracy and spatial coverage were investigated. These experiments used the state-of-the-art global OSSE system with a 7-km-resolution, non-hydrostatic nature run generated by NASA/GAMO, and a lower resolution version of the 2015-year NCEP’s operational suite. During this presentation, the design and most relevant results from these OSSEs will be discussed.