RADOLAN scale factor for RW product?

Corrections/Data Quality
1

Hello everyone,

I have converted RADOLAN data to xarray dataset.

dataset = xr.open_dataset('C:/Users/v-sandeepa/Desktop/Personal/Thesis/2022.nc')

dataset
Out[8]: 
<xarray.Dataset>
Dimensions:  (time: 8760, y: 254, x: 256)
Coordinates:
  * time     (time) datetime64[ns] 2022-01-01T00:50:00 ... 2022-12-31T23:50:00
  * y        (y) float64 -4.171e+06 -4.17e+06 ... -3.919e+06 -3.918e+06
  * x        (x) float64 8.904e+04 9.004e+04 9.104e+04 ... 3.43e+05 3.44e+05
Data variables:
    RW       (time, y, x) float32 ...
Attributes:
    radarid:         10000
    formatversion:   3
    radolanversion:  2.29.1
    radarlocations:  ['asb', 'boo', 'ros', 'hnr', 'umd', 'pro', 'ess', 'fld',...
    moduleflag:      1

rw_variable = dataset['RW']

rw_variable
Out[10]: 
<xarray.DataArray 'RW' (time: 8760, y: 254, x: 256)>
[569610240 values with dtype=float32]
Coordinates:
  * time     (time) datetime64[ns] 2022-01-01T00:50:00 ... 2022-12-31T23:50:00
  * y        (y) float64 -4.171e+06 -4.17e+06 ... -3.919e+06 -3.918e+06
  * x        (x) float64 8.904e+04 9.004e+04 9.104e+04 ... 3.43e+05 3.44e+05
Attributes:
    valid_min:      0
    valid_max:      4095
    standard_name:  rainfall_rate
    long_name:      RW
    unit:           mm h-1
    grid_mapping:   spatial_ref

# Group the data by time and calculate the mean along x and y dimensions
grouped_data = rw_variable.groupby("time").mean(dim=('x', 'y'))

grouped_data
Out[11]: 
<xarray.DataArray 'RW' (time: 8760)>
array([0.13057493, 0.16935617, 0.16515529, ...,        nan,        nan,
              nan], dtype=float32)
Coordinates:
  * time     (time) datetime64[ns] 2022-01-01T00:50:00 ... 2022-12-31T23:50:00
Attributes:
    valid_min:      0
    valid_max:      4095
    standard_name:  rainfall_rate
    long_name:      RW
    unit:           mm h-1
    grid_mapping:   spatial_ref

# Calculate the sum of precipitation for the entire year
yearly_precipitation_2022 = grouped_data.sum(dim='time')

yearly_precipitation_2022
Out[13]: 
<xarray.DataArray 'RW' ()>
array(2064.6753, dtype=float32)

From the above line, we can say annual precipitation for 2022 according to the code is 2064.7mm.

However, according to this [Annual rainfall of German federal states in 2022](Rainfall in Germany by season and annual average by year, month and land, federated state (ru-geld.de)) , annual rainfall is only 435mm.

I am wondering why there is so much difference. Is there any scale factor for RADOLAN data set? Seeking the help of experts @kmuehlbauer @mgrover1

Thanks in advance
sandeep