TH score update: EXTREME HEAT

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Hazard Processing Method

• Data Source: 3 return periods (RP5, RP20, RP100) - WBGT temperature rasters
• Unit: WBGT °C (Wet Bulb Globe Temperature)
• Default Thresholds: RP-specific (not single value)
• Default Area Threshold: 30%

RP-Specific Temperature Thresholds:

• RP5 > 32°C = High hazard
• RP20 > 28°C = Medium hazard
• RP100 > 25°C = Low hazard

Workflow:

1. For each RP, calculate percentage of pixels > RP-specific threshold
2. Check if area ≥ area threshold %
3. Assign highest qualifying score based on hierarchy:
   • If RP5 qualifies → Score 3 (High)
   • Else if RP20 qualifies → Score 2 (Medium)
   • Else if RP100 qualifies → Score 1 (Low)
   • Else → Score 0 (No hazard)

Scoring Logic:

• Hierarchical: RP5 takes precedence over RP20, which takes precedence over RP100
• Only the highest qualifying RP determines the final score
• Standard value threshold parameter is hidden (RP-specific thresholds used instead)

Output Columns:

• RP5_mean, RP20_mean, RP100_mean: Mean temperatures per RP
• RP5_area_pct, RP20_area_pct, RP100_area_pct: Affected area percentages
• Hazard_score: Final score (0-3)

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Comparison

New score distribution: ADM2

New score distribution: URBAN

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Original (2019) vs. 2025 Update

Data Overview

• Original Dataset: 38,229 administrative regions (ADM2 level)
• 2025 Dataset: 39,370 administrative regions (ADM2 level)
• High-Quality Matches: 33,207 regions (90%+ matching confidence)
• Unmatched Original: 5,022 regions
• Unmatched 2025: 6,268 regions

Technical Notes

• Hazard ranks: -1 = N/A, 0 = Very Low, 1 = Low, 2 = Medium, 3 = High
• Original data used text codes (VLO, LOW, MED, HIG), converted to numeric for easier comparison (delta)
• Matching threshold: 90% similarity required for inclusion in analysis
• Medium-quality matches (70-90%) available in separate sheet for manual review

Matching Method

Fuzzy string matching using hierarchical location names (Country | Admin1 | Admin2).
Only high-quality matches (≥90% similarity) were used for hazard comparison.

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• Regions Compared: 29,628
• Agreement: 88.4% (26,185 unchanged) ✓ HIGH AGREEMENT
• Net Trend: Slight downgrades (3,023 downgrades vs 420 upgrades)
• Average Change: -0.79 ranks
• Most Stable: This hazard showed the highest consistency

Comment

The slight changes only reflect the boundaries update and the minor differences in approach compared to original.