---
title: "Qc Report Endpoint"
method: GET
path: "/api/qc-report"
tags: ["Validation and QC"]
---

# Qc Report Endpoint

`GET /api/qc-report`

## Request

- Base URL: `https://epw.tools`
- URL: `https://epw.tools/api/qc-report`
- Auth: none declared

Compare a location's measured data against ERA5 and MERRA-2 reanalysis.

Both reanalysis products are free and require no API key:
  • ERA5:    via Open-Meteo archive API (non-commercial free tier)
  • MERRA-2: via NASA POWER API (unrestricted public access)

The endpoint returns chart-ready JSON including:
  - Monthly mean temperatures for station, ERA5, MERRA-2
  - 24-hour diurnal cycle comparison
  - Monthly bias  (station − reanalysis)
  - Statistical summary (bias, RMSE, R²) per reanalysis
  - A scatter sample of station vs ERA5 (≤ 500 points)
  - Quality flags if anomalies are detected

If ``station_id`` is supplied, the nearest NOAA ISD record for that station
in ``year`` is fetched and used as the station time series.  Without it,
only the reanalysis summaries are returned with no comparison statistics.

## Query parameters

- `lat` number, required: Latitude in decimal degrees
- `lon` number, required: Longitude in decimal degrees
- `year` integer, required: Calendar year to analyse (e.g. 2023)
- `station_id` string, nullable: ICAO / WMO station ID whose ISD data is fetched for comparison

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/epw/apis/epw-tools-api.md) · [All operations](https://skmtc.dev/epw/apis/epw-tools-api/llms.txt) · [OpenAPI document](https://skmtc.dev/epw/apis/epw-tools-api/revisions/e6b60fc7a6d7?raw)