Abstract. Radiosonde measurements
from the 1930s to present give unique information on the distribution and
variability of water vapor in the troposphere. The sounding data from the
Integrated Global Radiosonde Archive (IGRA) Version 2 are examined here until
the end of 2016, aiming to describe the completeness of humidity observations
(simultaneous measurements of pressure, temperature, and humidity) in
different times and locations. Upon finding the stations with a
non-negligible number of radiosonde observations in their period of record,
thus removing pilot-balloon stations from IGRA, the selected set (designated
IGRA-RS) comprises 1723 stations, including 1300 WMO stations, of which 178
belong to the current GCOS Upper-Air Network (GUAN) and 16 to the GCOS
Reference Upper-Air Network (GRUAN). Completeness of humidity observations
for a radiosonde station and a full year is herein defined by five basic
parameters: number of humidity soundings, fraction of days with humidity
data, average vertical resolution, average atmospheric pressure and altitude
at the highest measuring level, and maximum number of consecutive days
without data. The observations eligible for calculating precipitable water
vapor – i.e., having adequate vertical sampling between the surface and
500 hPa – are particularly studied. The present study presents the global
coverage of humidity data and an overall picture of the temporal and vertical
completeness parameters over time. This overview indicates that the number of
radiosonde stations potentially useful for climate studies involving humidity
depends 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 and
environmental scientists to select radiosonde data according to various
completeness criteria – even if differences in instrumentation and observing
practices require extra attention. This dataset consists of two main subsets:
(1) statistical metadata for each IGRA-RS station and year within the period
of record; and (2) metadata for individual observations from each station.
These are complemented by (3) a list of the stations represented in the whole
dataset, along with the observing periods for humidity (relative humidity or
dew-point depression) and the corresponding counts of observations. The
dataset is to be updated on a 2-year basis, starting in 2019, and is
available at https://doi.org/10.5281/zenodo.1332686.
Development and Assessment of the Atmospheric Pressure Vertical Correction Model With ERA‐Interim and Radiosonde Data
