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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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https://doi.org/10.5194/amt-2017-176
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
31 Jul 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Measurement Techniques (AMT).
Uncertainty Characterization of HOAPS-3.3 Latent Heat Flux Related Parameters
Julian Kinzel1, Marc Schröder1, Karsten Fennig1, Axel Andersson2, and Rainer Hollmann1 1Satellite-Based Climate Monitoring, Deutscher Wetterdienst, Frankfurter Strasse 135, 63067 Offenbach, Germany
2Marine Data Center, Deutscher Wetterdienst, Bernhard-Nocht-Straße 76, 20359 Hamburg, Germany
Abstract. Latent heat fluxes (LHF) are one of the main contributors to the global energy budget. As the density of LHF measurements over the global oceans is generally poor, the potential of remotely sensed LHF for meteorological applications is enormous. However, to date none of the available satellite products include estimates of systematic, random retrieval, and sampling uncertainties, all of which are essential for assessing their quality. Here, this challenge is taken on by applying regionally independent multi-dimensional bias analyses to LHF-related parameters (wind speed U, near-surface specific humidity qa, and sea surface saturation specific humidity qs) of the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite (HOAPS) climatology. In connection with multiple triple collocation analyses, it is demonstrated how both instantaneous (gridded) uncertainty measures may be assigned to each pixel (grid box). A high-quality in situ data archive including buoys and selected ships serves as the ground reference. Results show that systematic LHF uncertainties range between 15–50 W m-2 with a global mean of 25 W m-2. Local maxima are mainly found over the subtropical ocean basins as well as along the western boundary currents. Investigations indicate that contributions by qa (U) to the overall LHF uncertainty are in the order of 60 % (25 %). From an instantaneous point of view, random retrieval uncertainties are specifically large over the subtropics with a global average of 37 W m-2. In a climatological sense, their magnitudes become negligible, as do respective sampling uncertainties. Time series analyses show footprints of climate events, such as the strong El Niño during 1997/98. Regional and seasonal analyses suggest that largest total (i.e., systematic + instantaneous random) LHF uncertainties are seen over the Gulf Stream and the Indian monsoon region during boreal winter. In light of the uncertainty measures, the observed continuous global mean LHF increase up to 2009 needs to be treated with caution. First intercomparisons to other LHF climatologies (in situ, satellite) reveal overall resemblance with few, yet distinct exceptions.

Citation: Kinzel, J., Schröder, M., Fennig, K., Andersson, A., and Hollmann, R.: Uncertainty Characterization of HOAPS-3.3 Latent Heat Flux Related Parameters, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-176, in review, 2017.
Julian Kinzel et al.
Julian Kinzel et al.
Julian Kinzel et al.

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Short summary
Latent heat fluxes (LHF) play a major role in the climate system. Over open ocean, they are increasingly observed by satellite instruments. To access their quality, this research focuses on thorough uncertainty analysis of all LHF-related variables of the HOAPS satellite climatology, in parts making use of novel analysis approaches. Results indicate climatological LHF uncertainies up to 50 W m-2, whereby underlying specific humidities tend to be more uncertain than contributing wind speeds.
Latent heat fluxes (LHF) play a major role in the climate system. Over open ocean, they are...
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