From e594e381551c28437bae7869a09b3c1bbf906494 Mon Sep 17 00:00:00 2001
From: Yuxiang-Ren-HUB <165866978+Yuxiang-Ren-HUB@users.noreply.github.com>
Date: Fri, 7 Aug 2026 10:38:55 +0800
Subject: [PATCH 1/3] Fix get_nexrad_location mutating shared NEXRAD_LOCATIONS
 table

loc is a reference into the shared NEXRAD_LOCATIONS dict, not a copy.
Writing the feet->meters conversion back into loc["elev"] mutated the
table permanently, so a second call for the same station applied the
conversion again and silently corrupted the elevation.
---
 pyart/io/nexrad_common.py | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/pyart/io/nexrad_common.py b/pyart/io/nexrad_common.py
index 8b29470547..aee68235ec 100644
--- a/pyart/io/nexrad_common.py
+++ b/pyart/io/nexrad_common.py
@@ -26,11 +26,17 @@ def get_nexrad_location(station):
     """
     loc = NEXRAD_LOCATIONS[station.upper()]
 
-    # Convert from feet to meters for elevation units
-    loc["elev"] = loc["elev"] * 0.3048
-
-    return loc["lat"], loc["lon"], loc["elev"]
+    # Convert from feet to meters for elevation units. Read into a local
+    # variable and return a new value rather than writing back into
+    # loc["elev"] -- loc is a reference into the shared, module-level
+    # NEXRAD_LOCATIONS dict, so mutating it in place applied this
+    # conversion permanently. A second call for the same station then
+    # converted the already-converted value again, silently corrupting
+    # the elevation (e.g. KTLX: 1213 ft -> 369.72 m on the first call,
+    # then -> 112.7 m on the second).
+    elev_m = loc["elev"] * 0.3048
 
+    return loc["lat"], loc["lon"], elev_m
 
 # Locations of NEXRAD locations was retrieved from NOAA's
 # Historical Observing Metadata Repository (HOMR) on

From 0bb7da2f80573a304a0f85c9c1a888b1d564165a Mon Sep 17 00:00:00 2001
From: Yuxiang-Ren-HUB <165866978+Yuxiang-Ren-HUB@users.noreply.github.com>
Date: Fri, 7 Aug 2026 10:44:43 +0800
Subject: [PATCH 2/3] Add unit tests for nexrad_common location functions

Added unit tests for the nexrad_common module to verify location retrieval and stability across repeated calls.
---
 tests/io/test_nexrad_common.py | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 tests/io/test_nexrad_common.py

diff --git a/tests/io/test_nexrad_common.py b/tests/io/test_nexrad_common.py
new file mode 100644
index 0000000000..ff40d40fbe
--- /dev/null
+++ b/tests/io/test_nexrad_common.py
@@ -0,0 +1,29 @@
+"""Unit Tests for Py-ART's io/nexrad_common.py module."""
+
+import pytest
+
+from pyart.io import nexrad_common
+
+
+def test_get_nexrad_location_known_station():
+    lat, lon, elev = nexrad_common.get_nexrad_location("KTLX")
+    assert lat == pytest.approx(35.33306, abs=1e-3)
+    assert lon == pytest.approx(-97.2775, abs=1e-3)
+    # bundled table stores elevation in feet (1213 ft); function must
+    # return meters
+    assert elev == pytest.approx(1213 * 0.3048, abs=1e-6)
+
+
+def test_get_nexrad_location_repeated_calls_are_stable():
+    # Regression test: get_nexrad_location used to mutate the shared
+    # NEXRAD_LOCATIONS dict in place (loc["elev"] = loc["elev"] * 0.3048,
+    # where loc is a reference into the module-level table, not a copy).
+    # A second call for the same station then applied the feet->meters
+    # conversion again on top of the already-converted value, silently
+    # corrupting the elevation.
+    _, _, elev_first = nexrad_common.get_nexrad_location("KTLX")
+    _, _, elev_second = nexrad_common.get_nexrad_location("KTLX")
+    _, _, elev_third = nexrad_common.get_nexrad_location("KTLX")
+    assert elev_first == elev_second == elev_third
+    # and the underlying table itself must be untouched (still in feet)
+    assert nexrad_common.NEXRAD_LOCATIONS["KTLX"]["elev"] == 1213

From 80964eadf85d1a0276d6e6ee97fa91427f33fbdc Mon Sep 17 00:00:00 2001
From: rencheng <xiaoheibuku@gmail.com>
Date: Fri, 14 Aug 2026 08:33:00 +0800
Subject: [PATCH 3/3] Fix blank-line spacing to satisfy black

The previous commit left a single blank line between get_nexrad_location
and the following module-level comment block. Black requires two blank
lines after a top-level definition, so the Check Black job would have
failed once CI is allowed to run. No functional change.
---
 pyart/io/nexrad_common.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pyart/io/nexrad_common.py b/pyart/io/nexrad_common.py
index aee68235ec..6624a06878 100644
--- a/pyart/io/nexrad_common.py
+++ b/pyart/io/nexrad_common.py
@@ -38,6 +38,7 @@ def get_nexrad_location(station):
 
     return loc["lat"], loc["lon"], elev_m
 
+
 # Locations of NEXRAD locations was retrieved from NOAA's
 # Historical Observing Metadata Repository (HOMR) on
 # 2014-Mar-27. http://www.ncdc.noaa.gov/homr/