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Nudging is used when the aim of simulations is to reproduce the meteorology as close to reality as possible, for example when analyzing field campaigns or station data. Physics-side nudging is described in more detail herein the CAM User's Guide, Section 9.6. The default meteorology used is 3-hourly MERRA2 files on 32 levels. The power of physics-side nudging is we can choose to separately nudge different parameters (U, V, T, Q, PS) in different parts of the atmosphere, and for a set time range. The default set-up is to include zero nudging of surface pressure (PS) and specific humidity (Q), and nudge all other parameters (T, U, V) by the same amount everywhere (nudge_{x}coef = 0.06, nudge_{x}prof = 1). We recommended some updates to default values to improve model stability and performance:
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Note2: The default nudging coefficient of 0.06 is equivalent to 50-hour (or 1%) relaxation when used with using 3-hour meteorology. We recommend changing the default nudging coefficient for U, V and T to an intermediate value such as 0.25 (12 hour relaxation using 3-hour meteorology), adjusting other nudging parameters is recommended for advanced users. See the CAM User's Guide for information on additional parameters, in the Namelist Values table.
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&nudging_nl nudge_ucoef = 0.25 nudge_uprof = 1 nudge_vcoef = 0.25 nudge_vprof = 1 nudge_tcoef = 0.25 nudge_tprof = 1 nudge_pscoef = 0.00 nudge_psprof = 0 nudge_qcoef = 0.00 nudge_qprof = 0 / |
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