SPWV-H: A Spatially-enhanced Vertical Adjustment Model for Global Precipitable Water Vapor

<b>SPWV-H</b> is a MATLAB-based computational model designed for estimating global precipitable water vapor (PWV) based on a spatially-enhanced vertical adjustment approach. The model interpolates PWV values from surface grid data, accounting for height-dependent variations and geographic location. By integrating both exponential interpolation and cubic polynomial adjustments, this model allows for accurate estimations of PWV across different altitudes and latitudes.Key Features:<b>Grid-based Interpolation</b>: The model uses surface grid data from three distinct datasets (SPWV-H1, SPWV-H2, SPWV-H3) to estimate PWV values.<b>Vertical Adjustment</b>: Implements an exponential model for height-based interpolation and applies a cubic polynomial correction for low-latitude regions where no land is present.<b>Fourier-based Time Variability</b>: The model incorporates Fourier terms based on the day of year (DOY) to account for annual and semi-annual PWV cycles, making it suitable for time-series analysis.<b>Geographic Flexibility</b>: PWV estimates are adjusted for different geographic regions, with special consideration for low-latitude zones (between -30° and 30° latitude).Applications:<b>Climate Studies</b>: Useful for analyzing water vapor variations over time and space, especially in the context of climate change and atmospheric water cycle studies.<b>Weather and Climate Modeling</b>: Enhances numerical weather prediction models by providing accurate vertical PWV profiles.<b>Hydrological Studies</b>: Can be used to estimate water vapor contributions to precipitation and soil moisture in regional hydrological models.Requirements:<b>MATLAB</b> (Version R2016b or later).Data files for the three SPWV grid datasets (<code>SPWV-H1.txt</code>, <code>SPWV-H2.txt</code>, <code>SPWV-H3.txt</code>).How to Use:<b>Load Grid Data</b>: The model requires pre-processed grid data that contains surface-level PWV values and geographic coordinates (latitude, longitude, height).<b>Set Initial Parameters</b>: Define input parameters such as the beginning and ending height (in km), the initial PWV value (in mm), latitude, longitude, and day of the year (DOY).<b>Run the Model</b>: Call the <code>PWV_Interpolation_Model.m</code> script, which applies the vertical adjustment and spatial interpolation to compute the PWV for specified regions and heights.Citation:Yang, H., Ferreira, V., He, X., Zhan, W., Wang, X., Ji, S., 2025. Spatially enhanced interpolating vertical adjustment model for precipitable water vapor. J. Geod. 99, 12. https://doi.org/10.1007/s00190-025-01936-8