Radio blackout (R) scale

data/solar_conditions.py

@@ -5,7 +5,7 @@ from dataclasses import dataclass
 # Each threshold-based table is a list of (min_value, description) pairs in descending order;
 # the first entry whose threshold the value meets or exceeds is used.
 
-BLACKOUT_DESCRIPTIONS = {
+XRAY_CLASS_DESCRIPTIONS = {
     "X": "Wide area HF radio blackout across sunlit side",
     "M": "Occasional loss of HF communications on sunlit side",
     "C": "Low absorption of HF signals on sunlit side",
@@ -71,6 +71,28 @@ ELECTRON_FLUX_DESCRIPTIONS = [
 ]
 
 
+def _xray_blackout_scale(xray):
+    """Return the NOAA Radio Blackout scale number (R0-R5) for the given X-ray flux class string
+    (e.g. "M4.5", "X12")."""
+
+    if not xray or len(xray) < 2:
+        return 0
+    letter = xray[0].upper()
+    try:
+        number = float(xray[1:])
+    except ValueError:
+        return 0
+    if letter == 'M':
+        return 1 if number < 5 else 2
+    if letter == 'X':
+        if number < 10:
+            return 3
+        if number < 20:
+            return 4
+        return 5
+    return 0
+
+
 def _lookup_by_threshold(value, table, default=None):
     """Return the description from a threshold table for the given numeric value.
     The table is a list of (min_value, description) pairs in descending order."""
@@ -108,7 +130,7 @@ class SolarConditions:
     # K-index (3-hour geomagnetic activity)
     k_index: int = None
     # X-ray flux class, e.g. "B2.3", "C1.0"
-    x_ray: str = None
+    xray: str = None
     # Proton flux
     proton_flux: int = None
     # Electron flux
@@ -141,8 +163,10 @@ class SolarConditions:
     blackout_forecast_r3_or_greater: dict = None
 
     # Derived values (populated by infer_descriptions())
-    # HF radio blackout risk description, derived from x_ray
-    blackout_desc: str = None
+    # HF radio blackout risk description, derived from xray
+    xray_desc: str = None
+    # HF radio blackout scale number (R0-R5), derived from xray
+    radio_blackout_scale: int = None
     # Solar radiation storm level description, derived from proton_flux
     proton_flux_desc: str = None
     # Solar radiation storm scale number (S0-S5), derived from proton_flux
@@ -159,10 +183,9 @@ class SolarConditions:
     def infer_descriptions(self):
         """Populate derived text description fields from the current numeric/raw field values."""
 
-        # blackout_desc: use the X-ray flux class letter (first character of x_ray)
-        if self.x_ray and len(self.x_ray) > 0:
-            self.blackout_desc = BLACKOUT_DESCRIPTIONS.get(self.x_ray[0].upper())
-
+        if self.xray and len(self.xray) > 0:
+            self.xray_desc = XRAY_CLASS_DESCRIPTIONS.get(self.xray[0].upper())
+            self.radio_blackout_scale = _xray_blackout_scale(self.xray)
         self.proton_flux_desc = _lookup_by_threshold(self.proton_flux, PROTON_FLUX_DESCRIPTIONS)
         self.solar_storm_scale = _lookup_by_threshold(self.proton_flux, SOLAR_STORM_SCALES)
         self.geomag_storm_desc = _lookup_by_threshold(self.k_index, GEOMAG_STORM_DESCRIPTIONS)