Tropospheric and Boundary-Layer Water Vapor Isotopes over the Boreal Forest and Mediterranean Sea: Validation of Aura Tropospheric Emission Spectrometer Retrievals of HDO and H2O

Water vapor and HDO retrievals from the Tropospheric Emission Spectrometer (TES) on the EOS Aura platform have been compared with nearly coincident in situ airborne measurements. These measurements were made with commercially available Picarro L2130-I isotopic water analyzers on aircraft platforms over in the Alaskan Boreal forest interior during summers of 2011 and 2012, as well as aircraft measurements over the Mediterranean Sea near Sicily in 2012. TES Transect special observations were utilized in these comparisons. The TES averaging kernels and a priori constraints have been applied to the in situ data, using water vapor constraint vectors from GMAO GEOS-5 analyses for Version Five (V005) of TES data. TES calculated errors are compared with the rms (root mean square) of scan-to-scan variability to assess how much of the variability is attributable to TES observation error. Spatial and temporal variations are assessed from the in situ aircraft measurements. Over Alaska, a significant portion of the scan-to-scan variability is due to this atmospheric heterogeneity and vertical mixing. This variability was not observed over the Mediterranean and suggest that the water vapor isotope flux (primarily transpiration) from the vegetated surface of the Boreal contributes to the vertical heterogeneity from the upper to the lower atmosphereof the troposphere. The TES V005 bias in HDO/H2O will be reported in this presentation.