A combined high resolution global TCWV product from microwave and near infrared imagers - COMBI

The global total column water vapour (TCWV) data record combines microwave and near-infrared
imager based TCWV over the ice-free ocean and over land, coastal ocean as well as sea-ice,
respectively. The data record relies on microwave observations from SSM/I, SSMIS, AMSR-E and
TMI, partly based on a fundamental climate data record (Fennig et al., 2020; Fennig et al.,
2017) and on near-infrared observations from MERIS (3rd reprocessing), MODIS-Terra (collection
6.1) and OLCI (1st reprocessing). Details of the retrieval are described in Andersson et al.
(2010) and ATBD HOAPS for the microwave imagers as well as in Lindstrot et al. (2012),
Diedrich et al. (2015) and ABTD NIR Level 2 for the near-infrared imagers. The water vapour of
the atmosphere is vertically integrated over the full column and given in units of kg/m². The
microwave and near-infrared data streams are processed independently and combined afterwards
by not changing the individual TCWV values and their uncertainties. The combined data record
has a spatial resolution of 0.5°x0.5° and 0.05°x0.05°, with the near-infrared based data being
averaged and the microwave-based data being oversampled to match the lower and higher spatial
resolution, respectively. The product is available as daily and monthly means and covers the
period July 2002 – December 2017.