摘要：Radiosonde measurementsfrom the 1930s to present give unique information on the distribution andvariability of water vapor in the troposphere. The sounding data from theIntegrated Global Radiosonde Archive (IGRA) Version 2 are examined here untilthe end of 2016, aiming to describe the completeness of humidity observations(simultaneous measurements of pressure, temperature, and humidity) indifferent times and locations. Upon finding the stations with anon-negligible number of radiosonde observations in their period of record,thus removing pilot-balloon stations from IGRA, the selected set (designatedIGRA-RS) comprises 1723 stations, including 1300 WMO stations, of which 178belong to the current GCOS Upper-Air Network (GUAN) and 16 to the GCOSReference Upper-Air Network (GRUAN). Completeness of humidity observationsfor a radiosonde station and a full year is herein defined by five basicparameters: number of humidity soundings, fraction of days with humiditydata, average vertical resolution, average atmospheric pressure and altitudeat the highest measuring level, and maximum number of consecutive dayswithout data. The observations eligible for calculating precipitable watervapor – i.e., having adequate vertical sampling between the surface and500hPa – are particularly studied. The present study presents the globalcoverage of humidity data and an overall picture of the temporal and verticalcompleteness parameters over time. This overview indicates that the number ofradiosonde stations potentially useful for climate studies involving humiditydepends not only on their record length, but also on the continuity,regularity, and vertical sampling of the humidity time series. Additionally,a dataset based on IGRA is described with the purpose of helping climate andenvironmental scientists to select radiosonde data according to variouscompleteness criteria – even if differences in instrumentation and observingpractices require extra attention. This dataset consists of two main subsets:(1) statistical metadata for each IGRA-RS station and year within the periodof record; and (2) metadata for individual observations from each station.These are complemented by (3) a list of the stations represented in the wholedataset, along with the observing periods for humidity (relative humidity ordew-point depression) and the corresponding counts of observations. Thedataset is to be updated on a 2-year basis, starting in 2019, and isavailable at https://doi.org/10.5281/zenodo.1332686.
