The Polar Science Center Hydrographic Climatology (PHC) is a new global ocean climatology that merges the 1998 World Ocean Atlas (WOA98) with the Arctic Ocean Atlas (AOA). This dataset provides a high-quality description of the Arctic Ocean and its surroundings, including monthly, seasonal, and annual average products for temperature and salinity. The PHC was developed to address the need for a global gridded hydrography for climate modeling and analysis, especially as the role of the Arctic in global climate becomes more evident. The WOA98 dataset is sparse in the Arctic, with limited data available for winter and summer conditions. The AOA, created by the Environmental Working Group, provides gridded, interpolated data for the Arctic, including temperature and salinity. The PHC merges these datasets using optimal interpolation to create a unified global climatology. The AOA data were interpolated onto the WOA98 grid and adjusted to match the WOA98 format, ensuring minimal changes to the WOA98 outside the Arctic. The PHC includes a detailed description of the interpolation procedure, which involves defining a background field based on regional zonal averages and applying spatially varying correlation length scales and error variances. The error variances are set to reflect the reliability of the input data, with the WOA field having a higher variance than the AOA field in the Arctic region. The PHC results show improved representation of the Arctic Ocean compared to the WOA98, with corrected anomalies and more realistic salinity and temperature fields. The PHC provides a comprehensive view of the Arctic Ocean, including the convergence of relatively salty North Atlantic waters with relatively fresh North Pacific waters in the Arctic Ocean. The PHC is available on an internet website and includes a FORTRAN program for use with high-resolution models. The PHC is a valuable resource for climate research, providing a global climatology that includes the Arctic Ocean and its surroundings. Future work includes analyzing error variance across both WOA and AOA datasets and revisiting data merging techniques. The PHC is a community service to climate researchers and is available for download at an internet website.The Polar Science Center Hydrographic Climatology (PHC) is a new global ocean climatology that merges the 1998 World Ocean Atlas (WOA98) with the Arctic Ocean Atlas (AOA). This dataset provides a high-quality description of the Arctic Ocean and its surroundings, including monthly, seasonal, and annual average products for temperature and salinity. The PHC was developed to address the need for a global gridded hydrography for climate modeling and analysis, especially as the role of the Arctic in global climate becomes more evident. The WOA98 dataset is sparse in the Arctic, with limited data available for winter and summer conditions. The AOA, created by the Environmental Working Group, provides gridded, interpolated data for the Arctic, including temperature and salinity. The PHC merges these datasets using optimal interpolation to create a unified global climatology. The AOA data were interpolated onto the WOA98 grid and adjusted to match the WOA98 format, ensuring minimal changes to the WOA98 outside the Arctic. The PHC includes a detailed description of the interpolation procedure, which involves defining a background field based on regional zonal averages and applying spatially varying correlation length scales and error variances. The error variances are set to reflect the reliability of the input data, with the WOA field having a higher variance than the AOA field in the Arctic region. The PHC results show improved representation of the Arctic Ocean compared to the WOA98, with corrected anomalies and more realistic salinity and temperature fields. The PHC provides a comprehensive view of the Arctic Ocean, including the convergence of relatively salty North Atlantic waters with relatively fresh North Pacific waters in the Arctic Ocean. The PHC is available on an internet website and includes a FORTRAN program for use with high-resolution models. The PHC is a valuable resource for climate research, providing a global climatology that includes the Arctic Ocean and its surroundings. Future work includes analyzing error variance across both WOA and AOA datasets and revisiting data merging techniques. The PHC is a community service to climate researchers and is available for download at an internet website.