Figure 16. JJA diurnal cycle of precipitation as a function of local solar time in a 10-year S-SHiELD climate integration with the MLO nudged towards climatological SSTs, and from days 6–10 of three years of 13-km SHiELD hindcasts (initialized every five days), compared to TRMM 2011-2018 observations. Means are given in the legends as mm/day.
Hagos et al. (2016) found that the diurnal cycle of cloudiness and precipitation plays a key role in the propagation of the MJO through the Maritime Continent. Since S-SHiELD has considerably better diurnal cycles of precipitation and temperature over land, especially over tropical land, than do most climate models, we might expect that this improved representation of the diurnal cycle may be contributing to the improved representation of the MJO seen above.
4 Conclusion and Prospects
We have developed the SHiELD modeling system as a research tool to demonstrate new capabilities of the FV3 Dynamical Core and of our physical parameterizations, develop new ideas in atmospheric prediction modeling, and to explore processes and phenomena within the atmosphere. Since late 2015 when FV3 was first coupled to the then-operational GFS Physics Driver we have developed SHiELD into a promising vehicle for improving the prediction and understanding of atmospheric phenomena. SHiELD also demonstrates the potential and viability of unified modeling in which there is a single modeling system with one codebase, one executable, one preprocessor, one set of runscripts, and one set of post-processing tools. This greatly simplifies the modeling suite and allows improvements to be exchanged between configurations.
The fundamental characteristics of SHiELD compared to previous-generation and existing operational models are documented in this and other publications. For some applications we have previously demonstrated capabilities similar to that of existing modeling systems, such as severe-storm prediction in C-SHiELD (Harris et al 2019) and tropical cyclone intensity prediction in T-SHiELD (Hazelton et al 2018a,b). We have shown significant improvements over existing models, especially over existing global models, for large-scale and hurricane prediction skill in 13-km SHiELD (Zhou et al 2019, Chen et al 2019a), and the diurnal cycle and MJO prediction in S-SHiELD. We have even shown entirely new possibilities for prediction modeling, such as skillful hurricane intensity forecasts in 13-km SHiELD (Chen et al. 2019b), and the possibility of medium-range convective-scale prediction in C-SHiELD.