diff --git a/src/adsb/concat_parquet_to_final.py b/src/adsb/concat_parquet_to_final.py
new file mode 100644
index 0000000..669a6ae
--- /dev/null
+++ b/src/adsb/concat_parquet_to_final.py
@@ -0,0 +1,29 @@
+from pathlib import Path
+import polars as pl
+
+OUTPUT_DIR = Path("./data/output")
+
+compressed_dir = OUTPUT_DIR / "compressed"
+date_dirs = sorted(p for p in compressed_dir.iterdir() if p.is_dir())
+if not date_dirs:
+    raise FileNotFoundError(f"No date folders found in {compressed_dir}")
+
+start_date = date_dirs[0].name
+end_date = date_dirs[-1].name
+parquet_files = []
+for d in date_dirs:
+    parquet_files.extend(sorted(d.glob("*.parquet")))
+
+if not parquet_files:
+    raise FileNotFoundError("No parquet files found in compressed subfolders")
+
+frames = [pl.read_parquet(p) for p in parquet_files]
+df = pl.concat(frames, how="vertical", rechunk=True)
+
+df = df.sort(["time", "icao"])
+output_path = OUTPUT_DIR / f"openairframes_adsb_{start_date}_{end_date}.parquet"
+print(f"Writing combined parquet to {output_path} with {df.height} rows")
+df.write_parquet(output_path)
+csv_output_path = OUTPUT_DIR / f"openairframes_adsb_{start_date}_{end_date}.csv"
+print(f"Writing combined csv to {csv_output_path} with {df.height} rows")
+df.write_csv(csv_output_path)
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