From WRF output file,

I find 3 variables related to the precipitation (unit: mm)

1. Precipitation

  • variable name: pr
  • unit:$kg/(m^{2}s^1)$
  • variable: RAINC+RAINNC
  • comments: $dt(RAINC+RAINNC)/DT$

2. Max hourly precipitation rate

  • variable name: prhmax
  • unit:$kg/(m^{2}s^1)$
  • variable: RAINC, RAINNC or RAINMAX1Hclwrf
  • comments: $MAX(dtsum()/DT)$

3. Convective precipitation

  • variable name: prc
  • unit:$kg/(m^{2}s^1)$
  • variable: RAINC
  • comments: $d_t(RAINC)/DT $

My task:

Summarize the amount of days which precipitation > 0.254 mm

What variable should I use for further analysis?

Any advice would be appreciated.


1 Answer 1


Use (1) Precipitation, as it is the sum of convective and non-convective precipitation, integrate it over one day, voilà.

converting [$kg/(m^2 s)$] (precip): $$ precip [kg/(m^2 s)] \cdot dt [s] \cdot \frac{1}{ \rho_w [kg/(m^3)]} \cdot 1000 [mm/m] = total\_precip [mm]$$

where $\rho_w$ is the density of water.

Practically the last two factors cancel.

  • $\begingroup$ Thanks for your reply. I have known the meaning of sum RAINS & RAINNS. But you answer let me know why the units change to $mm$. That's very helpful! $\endgroup$ Mar 26, 2016 at 11:09

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