Figure data, plotting code, and RHtestsV4 configuration parameters for "Unaccounted instrumental changes caused apparent early 21st century land surface relative humidity sharp decline"

This deposit contains the figure-plotting data, plotting scripts, and RHtestsV4/PMTred homogenization configuration parameters used in the manuscript “Unaccounted instrumental changes caused apparent early 21st century land surface relative humidity sharp decline” (under review at Science Advances).

The manuscript homogenizes HadISD land-station relative humidity records using the reference-series Penalized Maximal T-test method implemented in RHtestsV4/PMTred. Breakpoints are detected from observation-minus-reference difference series, with sparse-input 20CRv3 reanalysis used as the reference series. The homogenized record shows that the widely reported early-21st-century decline in global land relative humidity is largely attributable to instrumental inhomogeneity associated with the transition from psychrometers to capacitive humidity sensors.

This deposit includes:
(1) processed data arrays used to generate all main-text and supplementary figures;
(2) Python plotting scripts based on matplotlib/cartopy to reproduce the figures without downloading the original raw datasets; and
(3) RHtestsV4/PMTred configuration files and parameter settings used for the homogenization procedure.