Decomposition of the large-scale atmospheric state driving downscaling: a perspective on dynamical downscaling for regional climate study

Progress in Earth and Planetary Science

Table 1 Possible large-scale states driving downscaling with reanalysis and GCM simulations in present and future climates

Perturbation	A ^′	Gp′	Gf′
Climatology
〈A〉	A	G_p−{G_p,A}
(=〈A〉+{A,A})	〈A〉+{A,A}+A^′	\(\langle A\rangle +\{A,A\}+G_{p}^{\prime }\)	\(\langle A\rangle +\{A,A\}+G_{f}^{\prime }\)
	Present DDS (reanalysis)	Present Unbiased-DS
〈G_p〉		G _p
(=〈A〉+{G_p,A})	〈A〉+{G_p,A}+A^′	\(\langle A\rangle +\{G_{p},A\}+G_{p}^{\prime }\)	\(\langle A\rangle +\{G_{p},A\}+G_{f}^{\prime }\)
		Present DDS (GCM)
〈UG_f〉	A+{G_f,G_p}		G_f−{G_p,A}
(=〈A〉+{G_f,G_p})	〈A〉+{G_f,G_p}+A^′	\(\langle A\rangle +\{G_{f},G_{p}\}+G_{p}^{\prime }\)	\(\langle A\rangle +\{G_{f},G_{p}\}+G_{f}^{\prime }\)
	Pseudo-Clim-DS		Future Unbiased-DS
〈G_f〉		G_p+{G_f,G_p}	G _f
(=〈A〉+{G_f,A})	〈A〉+{G_f,A}+A^′	\(\langle A\rangle +\{G_{f},A\}+G_{p}^{\prime }\)	\(\langle A\rangle +\{G_{f},A\}+G_{f}^{\prime }\)
		ATC-Pseudo-Clim-DS	Future DDS

The top, middle, and bottom rows in each cell represent the original form, decomposition form, and corresponding downscaling method, respectively. The climatology and perturbation of a state are represented by 〈〉 and prime, respectively, and the climate difference by { }