Time series of Precipitable Water residuals (observed minus calculated from 2-m dew point temperature) for 2025-12-07 to 2025-12-08.

Description

The visualization presents a time series plot of residuals computed as observed PWATCLM (precipitable water in the atmospheric column) minus PWATCLM values calculated from 2-m dew point temperature (dpt2m) using the empirical exponential formula PWATCLM_calc = 10 × exp(0.1102 + 0.0614 × dpt2m). Over the period from 2025-12-07 00:00 to 2025-12-08 03:00 (10 data points at 3-hour intervals), residuals are consistently negative, ranging from -4.46 to -1.82, indicating systematic overestimation of PWATCLM by the formula. The residuals show temporal fluctuations, with the least negative value (-1.82) at 15:00 on December 7, potentially reflecting diurnal atmospheric variations, and more negative values during early morning hours. Linear regression between PWATCLM_calc (independent) and PWATCLM_obs (dependent) demonstrates strong linear agreement (R² = 0.87), but with a slope >1 and negative intercept, confirming both scale mismatch and offset. This suggests the formula captures much of the variability in PWATCLM driven by dew point temperature but requires bias correction for accurate application in models or forecasts.

Tags