4DVD visualization and delivery of the 20th century reanalysis data: methods and examples

Abstract

This paper describes the use of a web application system, called 4-Dimensional Visual Delivery (4DVD), to visualize and deliver climate data. The focus of this paper is on the monthly data from the NOAA-CIRES-DOE Twentieth Century Reanalysis (20CR) project Version 2c. The 20CR is a global model at a spatial resolution about 2° latitude-longitude. The temporal coverage is from January 1851 to December 2014. The monthly data include numerous climate variables, such as temperature, pressure, precipitation rate, zonal wind, meridional wind, albedo, and longwave radiation flux. We show how to use the 4DVD system to conveniently visualize, deliver, and analyze the 20CR data of these parameters on a globe or on a 2D latitude-longitude map. We analyze the temporal and spatial patterns of zonal wind and precipitation over Nino 4 region (5° N-5° S, 160° E-150° W). The monthly NASA Global Precipitation Climatology Project (GPCP) data are used to compare the results from 20CR. GPCP data used in this 4DVD application are defined on 2.5° latitude-longitude grid boxes from January 1979 to January 2019. The 4DVD figures successfully show the reverse of zonal wind direction from the east-to-west wind to the west-to-east wind on the grid box (2° S, 176° W) in the Nino 4 region during an El Nino event. The spectral analysis shows the annual and semi-annual cycles in the zonal wind data on this grid box. The GPCP data are used to support the analysis results of 20CR zonal data. The precipitation data over the grid box (1.25° S, 176.25° W) in the Nino 4 region show clear El Nino signals (persistent extreme precipitation more than 6 mm/day) and clear La Nina signals (persistent “dry” with near-zero precipitation). The spectral analysis of the precipitation data time series over this grid box shows no annual cycle.