GHCNh User Guide

Comprehensive user guide for the GHCNh Explorer, detailing how to navigate the map, filter stations, and visualize hourly climate data.

Access the Application: Return to Explorer

1. Introduction

The GHCNh Explorer is an interactive dashboard for exploring Global Historical Climatology Network hourly (GHCNh) data. It allows you to visualize detailed weather records from thousands of stations worldwide, including temperature, precipitation, wind, and pressure data.

2. Global Navigation (Sidebar)

The sidebar on the left controls the global view of the application.

• Select Country: Filter the displayed stations by country. Leave empty to see all stations.
• Select Date Selection: Define the “Global Window” for analysis.
  • Max Window: The range is limited to 366 days to ensure performance with high-resolution hourly data.
  • Smart Sliding:
    • Dragging the Start Date backward moves the entire window back (Anchor Start).
    • Dragging the End Date forward moves the entire window forward (Anchor End).
• Download Stations: Exports a CSV list of all currently visible stations (filtered by country/bounds).

Try it out: Explore Tokyo Data

To see a great example of historical data from Asia: 1. In Select Country, choose Japan. 2. On the map or in the Stations Info table, look for TOKYO (ID: JAI0000RJTD). 3. Select it to see a rich dataset of temperature, pressure, and precipitation.

3. Main Navigation Tabs

The application features three main tabs at the top:

Map View

Application Map View

The default view is an interactive map showing available weather stations.

• Blue Dots: Represent stations available within your selected filters.
• Selection: Click any blue dot to select a station.
  • Red Highlight: The selected station is highlighted with a red ring.
  • Persistence: Note that even if you change global filters (like the date range) that might hide the station from the general list, the selected station remains highlighted so you never lose your place.

Stations Info

A tabular listing of all available stations. This view is useful for browsing the full station catalog.

• Double-Click: Double-click any row to load that station’s data and navigate directly to the Dashboard.

Dashboard

Dashboard View

The Dashboard displays detailed data for a selected station. It only becomes active after selecting a station from the map or double-clicking a row in the Stations Info table.

Dashboard Header

• Station Info: Name, ID, Country, Elevation, and Data Period.
• Export CSV: Download the parsed data for the currently viewed period.

Dashboard Sub-Tabs

The Dashboard contains two sub-tabs:

1. Plots: Specialized visualization tabs for different weather parameters:
   • Overview: A comprehensive 5-panel timeline showing Temperature & Dew Point, Wind Speed & Gusts, Pressure (MSL & Station), Relative Humidity, and Visibility.
   • Precipitation: Stacked bar charts showing precipitation accumulations across different intervals (1h, 3h, 6h, 24h).
   • Wind: A Wind Rose diagram showing the frequency distribution of wind speed and direction.
   • Weathergami: A heatmap of Daily Max vs. Daily Min temperatures, visualizing the station’s climate signature.
   • Diurnal: Shows the daily temperature cycle with median hourly temperature (red line) and individual daily traces (grey lines).
2. Data: Provides raw data access with nested tabs for different resolutions.
   • Hourly: The detailed hour-by-hour dataset with an Export Hourly CSV button.
   • Daily: A generated daily summary table with an Export Daily CSV button.

4. Parameter Reference

The following tables list the parameters available in the GHCNh Explorer for each resolution. These parameters correspond to the column names in the exported CSV files.

Hourly Parameters

Column Name	Definition	Unit
datetime	Observation Timestamp	UTC
temp	Air Temperature	°C
dew_point	Dew Point Temperature	°C
rh	Relative Humidity	%
precip	Precipitation (1h)	mm
precip_3h … precip_24h	Precipitation Accumulations	mm
wind_speed	Wind Speed	m/s
wind_dir	Wind Direction	degrees
wind_gust	Wind Gust	m/s
pressure	Sea Level Pressure	hPa
station_pressure	Station Level Pressure	hPa
altimeter	Altimeter Setting	hPa
vis	Visibility	m
wet_bulb	Wet Bulb Temperature	°C
snow_depth	Snow Depth	cm
sky_cover_1 … sky_cover_3	Sky Cover Layers	oktas
sky_baseht_1 … sky_baseht_3	Cloud Base Height	m
pres_wx_mw1 … pres_wx_mw3	Present Weather (Manual)	Code
pres_wx_au1 … pres_wx_au3	Present Weather (Auto)	Code
pres_wx_aw1 … pres_wx_aw3	Present Weather (Auto - Recent)	Code

Daily Parameters

Column Name	Definition	Unit
date	Date	YYYY-MM-DD
Tavg	Average Temperature	°C
Tmax	Maximum Temperature	°C
Tmin	Minimum Temperature	°C
Precip_Sum	Total Precipitation	mm
Wind_Max	Maximum Hourly Wind Speed	m/s
RH_Avg	Average Relative Humidity	%
Pavg	Average Pressure	hPa
Vis_Avg	Average Visibility	m

5. Direct Data Access

Advanced users can download the full historical raw data (Pipe Separated Values - .psv) directly from the NOAA NCEI repository.

• Base URL: https://www.ncei.noaa.gov/oa/global-historical-climatology-network/hourly/access/by-station/
• File Naming Convention: GHCNh_<Station_ID>_por.psv

Finding Station IDs

You can find the Station ID for any location in the Stations Info tab of the application, or by downloading the station list CSV.

Example: To download the data for TOKYO (ID: JAI0000RJTD): https://www.ncei.noaa.gov/oa/global-historical-climatology-network/hourly/access/by-station/GHCNh_JAI0000RJTD_por.psv