IASI temperature and water vapor retrievals – error assessment and validation

Abstract

Abstract. The METOP-A satellite Infrared AtmosphericSounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze.

The MUSICA MetOp/IASI H<sub>2</sub>O and δD products: characterisation and long-term comparison to NDACC/FTIR data

“…7 for all three FTIR measurement sites and three different altitudes. The altitudes are selected according to the comparability estima- The good agreement observed here is consistent with previous studies that compared IASI H 2 O profile products to meteorological radiosonde data (Pougatchev et al, 2009;Schneider and Hase, 2011a;August et al, 2012). …”

“…The good agreement observed here is in consistency with previous studies that compared IASI H 2 O profile products to meteorological radiosonde data (Pougatchev et al, 2009;Schneider and Hase, 2011a;August et al, 2012). The solid lines in the right panel of Figure 6 depicts the comparability values diag(S c )/ diag(S a ) for product type 2, i. e., S c is calculated according to Eq.…”

Comparison of IASI water vapor retrieval with H<sub>2</sub>O-Raman lidar in the framework of the Mediterranean HyMeX and ChArMEx programs

“…Moreover, few validations are available in the scientific literature. Pougatchev et al (2009) used rawindsounding measurements to assess the error covariance matrix needed for the inversion algorithm. Masiello et al (2013) argue that lidar measurements are excellent candidates for the validation of spaceborne sensors.…”

Observation of tropospheric δD by IASI over western Siberia: comparison with a general circulation model

“…We modify the temperature profiles of 0.5 % at each level. This perturbation is larger than the uncertainties found in Pougatchev et al (2009). Differences between the origi- …”