> For the complete documentation index, see [llms.txt](https://eflow.gitbook.io/ffc-readme/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eflow.gitbook.io/ffc-readme/functional-flow-calculator/metrics/dry-season-low-flows/magnitude.md).

# Magnitude

## Definition

The magnitude of the dry season is calculated as the 50th and 90th percentile of the flows ranging from the start date of the dry season baseflow period until the start date of the wet season. This metric is measured in units of cfs.

## Steps

1. The timing of the start of the dry season baseflow period and the start of the wet season must first be calculated, and then passed into the calculation for the dry season baseflow magnitude.

   ```python
   def calc_summer_baseflow_durations_magnitude(flow_matrix, summer_start_dates, fall_flush_dates, fall_flush_wet_dates):
   ```
2. Identify the range of flow data corresponding to the start of the dry season baseflow period until the start of the wet season.

   ```python
   flow_data_wet = list(flow_matrix[su_date:,column_number]) + list(flow_matrix[:wet_date, column_number])
   ```
3. Calculate the dry season baseflow magnitude as the 10th percentile of flows ranging from the start of the dry season low flow period until the start of the wet season.

   ```python
   if not np.isnan(summer_start_date) and not np.isnan(fall_flush_wet_dates[column_number]):
      su_date = int(summer_start_date)
      wet_date = int(fall_flush_wet_dates[column_number])
   if not np.isnan(fall_flush_wet_dates[column_number]):
      flow_data_wet = list(flow_matrix[su_date:,column_number]) + list(flow_matrix[:wet_date, column_number])
   summer_50_magnitudes.append(np.nanpercentile(flow_data_wet, 50))
   summer_90_magnitudes.append(np.nanpercentile(flow_data_wet, 90))
   ```