Corrections — Tokyo Temp

Our Correction Policy

We believe in transparency about our mistakes. When we discover an error in our published data, analysis, or writing, we correct it promptly and record the correction on this page with the date of discovery and the nature of the error. We do not silently edit our content. If you believe you have found an error in our work, please contact us with the details and we will investigate.

Published Corrections

Correction — March 15, 2024

Error: The August 2023 asphalt surface temperature reading of 67°C reported on the Urban Materials page was incorrect. The actual measured value was 64.3°C. The 67°C figure resulted from a calibration drift in our IR camera that was not detected until the post-survey calibration check.

Correction: The text has been updated to state 64.3°C. The 2.7°C overestimate did not affect any of our thermal lag calculations, which use air temperature data from fixed sensors, not surface temperature readings.

Impact: Low. The corrected value does not change any conclusions about the relative thermal performance of asphalt vs. other surfaces.

Correction — February 2, 2024

Error: The specific heat capacity of asphalt listed in the Urban Materials essay was stated as 850 J/kg·K. The correct value for typical Tokyo road asphalt is 920 J/kg·K. The 850 J/kg·K figure was a typographical error carried over from an early draft that confused asphalt with a different paving material.

Correction: The value has been updated to 920 J/kg·K throughout the site. The thermal mass index calculation for asphalt has been recalculated and remains at 92/100.

Impact: Low. The corrected value strengthens rather than weakens our argument about asphalt's high thermal storage capacity.

Correction — November 20, 2023

Error: The ward comparison table on the District Delay page originally listed Nerima Ward's thermal lag as 24 days. The correct value, based on our 2021–2023 cross-correlation analysis, is 22 days. The 24-day figure was from a preliminary analysis using incomplete 2021 data.

Correction: The table has been updated with the correct value of 22 days. Nerima remains the ward with the lowest thermal lag in the 23-ward set.

Impact: Low. The ranking of wards by lag is unchanged.

Correction — September 8, 2023

Error: An earlier version of the Seasonal Shift essay stated that the Tokyo Fire Department reported 3,200 heat stroke transports in September 2022. The correct figure is 2,847 transports. The 3,200 figure included August data that was accidentally included in the September tally due to a spreadsheet sorting error on our part.

Correction: The text and any associated analysis have been updated with the correct figure of 2,847. The conclusion — that September heat illness risk is comparable to August — remains valid.

Impact: Moderate. The error overstated September 2022 cases by 12.4%.

Correction — July 12, 2023

Error: The building coverage percentage for Minato Ward was listed as 48% in the District Delay comparison table. The correct figure from the Tokyo Metropolitan Government GIS data is 44%. The 48% figure was a transposition error from Shinjuku Ward's entry.

Correction: The table has been updated with the correct value of 44%. Minato's lag estimate of 29 days was calculated using the correct coverage data and is unaffected.

Impact: Low. The correction improves the accuracy of the building-lag regression but does not change the regression coefficient significantly.

Correction — April 3, 2023

Error: The Seasonal Lag essay originally stated that the cross-correlation coefficient for Chiyoda Ward was r = 0.97. The correct value is r = 0.94. The 0.97 figure came from a preliminary calculation that used unnormalized data, producing an inflated correlation.

Correction: All references to the Chiyoda correlation coefficient have been updated to 0.94. The confidence interval has been recalculated as 32–36 days (previously stated as 33–35 days).

Impact: Moderate. The corrected correlation is still very strong, but the precision of the lag estimate is slightly reduced.

Clarification — January 10, 2023

Issue: Several readers asked whether our thermal lag calculation accounts for the effect of the Pacific Ocean on Tokyo's temperature patterns. The original Data Sources page did not explicitly address this.

Clarification: Our cross-correlation method captures all temperature variability, including maritime influences. However, we do not explicitly separate oceanic thermal inertia from urban thermal lag in our published analysis. Coastal wards (Minato, Koto, Shinagawa) have lower lag partly due to maritime moderation, but our regression model attributes this effect to water surface coverage rather than oceanic heat transport. We have added a paragraph to the Data Sources page clarifying this limitation.

Impact: This is a clarification of methodology, not a correction of fact. No data values were changed.

How We Handle Corrections

When we discover an error, we follow this procedure:

1. Verify: We independently verify the error using our raw data and analysis code before making any changes.

2. Correct: We update the affected content on the website with the accurate information.

3. Document: We add an entry to this Corrections page with the date, the nature of the error, the correction made, and our assessment of the impact on our conclusions.

4. Notify: For significant corrections (those that change a numerical value by more than 10% or affect a core conclusion), we note the correction at the top of the affected page for 30 days.

5. Archive: We maintain a version history of all significant corrections for future reference.

Reporting Errors

If you believe you have found an error in our data, analysis, or writing, please email us at research@tokyo-temp.com with the subject line "Error Report." Include the page where you found the error, the incorrect text or value, what you believe the correct value should be, and your source or reasoning. We aim to acknowledge all error reports within 48 hours and resolve them within 14 days.

We credit external error reporters by name on this page unless they request anonymity. We are grateful to everyone who helps us improve the accuracy of our work.