Semper et al. (2026) Sensitivity of Consecutive‐Dry‐Day Trends to Trace Loss in Matched Precipitation Archives

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: International Journal of Climatology
• Year: 2026
• Date: 2026-09-23
• Authors: Marc Semper, Manuel Curado, José F. Vicent, Jorge Olcina Cantos
• DOI: 10.1002/joc.70597

Research Groups

Not specified in the provided text.

Short Summary

This study evaluates how different data provider versions of the same precipitation gauges affect the Consecutive Dry Days (CDD) index, revealing that the inconsistent handling of trace precipitation can create artificial trends in drought duration.

Objective

• To determine whether different provider versions of the same physical gauge preserve the sequence of dry, wet, and missing observation states and to quantify the impact of trace precipitation loss on CDD trend calculations.

Study Configuration

• Spatial Scale: Global (24 countries, with specific focus on Spain and the GHCN-Daily network).
• Temporal Scale: Multi-year time series (specific date range not provided, but analyzed via trends in days yr$^{-1}$).

Methodology and Data

• Models used: Consecutive Dry Days (CDD) index; counterfactual degradation experiments (converting trace precipitation to missing values).
• Data sources: 8020 matched station-version pairs from various providers, including AEMET (Spain), ECA&D, and GHCN-Daily.

Main Results

• Mechanism of Error: Discrepancies in CDD are primarily driven by the loss of valid trace precipitation followed by spell-breaking gaps in the data.
• Regional Sensitivity: In Spain, the impact is most severe in arid regions, where 41.2% of the driest stations changed CDD trend classification between versions, compared to 17.6% in the wettest stations.
• Global Impact: A counterfactual analysis of GHCN-Daily data showed that degrading trace flags to missing values alters the CDD trend classification at 5.96% of stations globally.
• Non-stationarity: Trace reporting is not constant over time; 60.9% of trace-exposed stations show a significant trend in trace-day frequency, with 72.3% of those showing a decline.
• Quantitative Shift: These encoding choices can imprint directional shifts on fitted CDD trends of up to $\pm 0.24$ days yr$^{-1}$.

Contributions

The research highlights a critical source of observational uncertainty in precipitation-duration climatology, demonstrating that differences in archive processing and the treatment of trace precipitation can be erroneously interpreted as actual climatic changes in drought duration.

Funding

Not specified in the provided text.

Citation

@article{Semper2026Sensitivity,
  author = {Semper, Marc and Curado, Manuel and Vicent, José F. and Cantos, Jorge Olcina},
  title = {Sensitivity of Consecutive‐Dry‐Day Trends to Trace Loss in Matched Precipitation Archives},
  journal = {International Journal of Climatology},
  year = {2026},
  doi = {10.1002/joc.70597},
  url = {https://doi.org/10.1002/joc.70597}
}