From d9f8decbd2b0424b0e0b1e028a6857427110e3d9 Mon Sep 17 00:00:00 2001
From: Since <ax20yhum@cip.cs.fau.de>
Date: Sun, 19 Mar 2017 22:08:07 +0100
Subject: [PATCH] Allow various Z-R relationships
---
conversion.go | 26 ++++++++++++++++++++------
conversion_test.go | 4 ++--
2 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/conversion.go b/conversion.go
index ea0a541..1e63325 100644
--- a/conversion.go
+++ b/conversion.go
@@ -10,16 +10,30 @@ type DBZ float64
// Raw radar video processor value.
type RVP6 float64
+// Z-R relationship mathematically expressed as Z = a * R^b
+type ZR struct {
+ A float64
+ B float64
+}
+
+// Common Z-R relationships
+var (
+ Aniol80 = ZR{256, 1.42} // operational use in germany, described in [6]
+ Doelling98 = ZR{316, 1.50} // operational use in switzerland
+ JossWaldvogel70 = ZR{300, 1.50}
+ MarshallPalmer55 = ZR{200, 1.60} // operational use in austria
+)
+
// PrecipitationRate returns the estimated precipitation rate in mm/h for the given
-// reflectivity factor. The used Z-R relation is described in [6].
-func (z DBZ) PrecipitationRate() float64 {
- return math.Pow(math.Pow(10, float64(z)/10)/256, 1/1.42)
+// reflectivity factor and Z-R relationship.
+func (z DBZ) PrecipitationRate(relation ZR) float64 {
+ return math.Pow(math.Pow(10, float64(z)/10)/relation.A, 1/relation.B)
}
// Reflectivity returns the estimated reflectivity factor for the given precipitation
-// rate (mm/h). The used Z-R relation is described in [6].
-func Reflectivity(rate float64) DBZ {
- return DBZ(10 * math.Log10(256*math.Pow(rate, 1.42)))
+// rate (mm/h) and Z-R relationship.
+func Reflectivity(rate float64, relation ZR) DBZ {
+ return DBZ(10 * math.Log10(relation.A*math.Pow(rate, relation.B)))
}
// ToDBZ converts the given radar video processor values (rvp-6) to radar reflectivity
diff --git a/conversion_test.go b/conversion_test.go
index 007c8ec..8f29d45 100644
--- a/conversion_test.go
+++ b/conversion_test.go
@@ -19,8 +19,8 @@ func TestConversion(t *testing.T) {
for _, test := range testcases {
dbz := test.rvp.ToDBZ()
- zr := dbz.PrecipitationRate()
- rz := Reflectivity(zr)
+ zr := dbz.PrecipitationRate(Aniol80)
+ rz := Reflectivity(zr, Aniol80)
rvp := dbz.ToRVP6()
if dbz != test.dbz {
--
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