Tonga Subnational Rainfall: Dekadal Totals, Anomalies, and Forecasts

Tonga subnational rainfall indicators provided by the World Food Programme (WFP) feature dekadal (10-day) totals and anomalies derived from CHIRPS satellite imagery. The data covers administrative units identified by Pcodes and includes both historical averages and short-term forecasts updated six times monthly. It tracks precipitation across 10-day, 1-month, and 3-month windows to monitor climate deviations.

Use Cases

• Drought assessment using the 3-month rainfall anomaly (r3q) to identify subnational moisture stress
• Agricultural cycle monitoring by comparing current 10-day rainfall (rfh) against the long-term average (rfh_avg)
• Climate trend analysis using the type column to filter for final validated observations versus forecasts

Strengths

• Standardized Pcode references for administrative units
• Includes pixel count metadata (n_pixels) for data quality assessment
• Provides both historical averages and short-term forecasts in a single schema

Limitations

• Satellite-derived estimates may deviate from local rain gauge data
• 10-day temporal resolution precludes daily weather analysis
• Data status transitions from forecast to final, requiring users to manage version updates

Provenance

Source

World Food Programme (WFP) using CHIRPS v2 and CHIRPS-GEFS

Collection Method

Satellite imagery (CHIRPS) integrated with in-situ station data and short-term forecasts

Freshness

Updated six times per month on the 1st, 6th, 11th, 16th, 21st, and 26th.

Geography

Tonga