Japan Subnational Dekadal Rainfall Indicators and Anomalies

Dekadal rainfall indicators for Japan's subnational units include 10-day, 1-month, and 3-month precipitation totals, anomalies, and long-term averages. Produced by the World Food Programme using CHIRPS v2 satellite imagery and CHIRPS-GEFS forecasts, the data is updated six times monthly to transition from initial forecasts to final observations.

Use Cases

• Assessing localized drought severity by analyzing the 3-month rainfall anomaly percentage (`r3q`) for specific subnational units
• Predicting upcoming moisture availability for crop cycles using the 10-day rainfall forecast (`rfh`) filtered by the `type` column
• Evaluating historical climate deviations by comparing current 1-month rolling aggregations (`r1h`) against their long-term averages (`r1h_avg`)

Strengths

• Standardized spatial referencing using WFP Pcodes for subnational administrative units
• Multi-stage data lifecycle tracking through 'forecast', 'preliminary', and 'final' status in the `type` column
• Includes pixel count metadata (`n_pixels`) to indicate the data density used for each subnational aggregate

Limitations

• Satellite-based CHIRPS data may exhibit biases in mountainous regions compared to dense local gauge networks
• The 10-day dekadal temporal resolution prevents analysis of specific daily extreme weather events

Provenance

Source

World Food Programme (WFP)

Collection Method

Satellite imagery and in-situ station data aggregation

Freshness

Updated six times per month

Geography

Japan