RAINRATE hack

[JordanLaserGit]

Currently forcingprocessor contains a poor hack to calculate precip_rate for NextGen. RAINRATE should be converted in a physically consistent way.

nwm_variables = [
    "U2D",
    "V2D",
    "LWDOWN",
    "RAINRATE",
    "RAINRATE",
    "T2D",
    "Q2D",
    "PSFC",
    "SWDOWN",
]

global ngen_variables
ngen_variables = [
    "UGRD_10maboveground",
    "VGRD_10maboveground",
    "DLWRF_surface",
    "APCP_surface",
    "precip_rate",  # HACK RAINRATE * 3600
    "TMP_2maboveground",        
    "SPFH_2maboveground",
    "PRES_surface",
    "DSWRF_surface",
] 

[JordanLaserGit]

It looks like we need to implement the code recommended here:
NOAA-OWP/ngen#302
and here:
NOAA-OWP/ngen#509

def rho(temp): 
    """
        Calculate water density at temperature
    """
    return 999.99399 + 0.04216485*temp - 0.007097451*(temp**2) + 0.00003509571*(temp**3) - 9.9037785E-8*(temp**4) 

And

def aorc_as_rate(dataFrame):
    """
        Convert kg/m^2 -> m/s
    """
    if isinstance(dataFrame.index, pd.MultiIndex):
        interval = pd.Series(dataFrame.index.get_level_values(0))
    else:
        interval = pd.Series(dataFrame.index)
    interval = ( interval.shift(-1) - interval ) / np.timedelta64(1, 's')
    interval.index = dataFrame.index
    precip_rate = ( dataFrame['APCP_surface'].shift(-1) / dataFrame['TMP_2maboveground'].apply(rho) ) / interval
    precip_rate.name = 'precip_rate'
    return precip_rate

[jameshalgren]

@chp2001 -- something you could do?
@JoshCu

[arpita0911patel]

@bduwuri

[JordanLaserGit]

Coming back to this issue... it looks like the rain rate hack was removed.

However, the current implementation just reads the variables directly (without any physical transformation... which is still bad and should be addressed.
Variables defined here.
Conversion can be inserted here or else where if appropriate.

[JordanLaserGit]

Development on forcingprocessor has moved to https://github.com/CIROH-UA/forcingprocessor/tree/main