![Hier klicken, um den Treffer aus der Auswahl zu entfernen](images/unchecked.gif) |
Titel |
Systematic and random uncertainties of HOAPS-3.2 evaporation |
VerfasserIn |
Julian Kinzel, Karsten Fennig, Marc Schröder, Axel Andersson, Karl Bumke, Felix Dietzsch |
Konferenz |
EGU General Assembly 2015
|
Medientyp |
Artikel
|
Sprache |
Englisch
|
Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250104262
|
Publikation (Nr.) |
EGU/EGU2015-3681.pdf |
|
|
|
Zusammenfassung |
The German Research Foundation (DFG) funds the research programme ”FOR1740 –
Atlantic freshwater cycle“, which aims at analysing and better understanding the freshwater
budget of the Atlantic Ocean and the role of freshwater fluxes (evaporation minus
precipitation) in context of oceanic surface salinity variability.
It is well-known that these freshwater fluxes play an essential role in the global
hydrological cycle and thus act as a key boundary condition for coupled ocean-atmosphere
general circulation models.
However, it remains unclear as to how uncertain evaporation (E) and precipitation (P )
are. Once quantified, freshwater flux fields and their underlying total uncertainty (systematic
plus random) may be assimilated into ocean models to compute ocean transports and
run-off estimates, which in turn serve as a stringent test on the quality of the input
data.
The Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data
(HOAPS) (Andersson et al. (2010), Fennig et al. (2012)) is an entirely satellite-based
climatology, based on microwave radiometers, overcoming the lack of oceanic in-situ
records.
Its most current version, HOAPS-3.2, comprises 21 years (1987–2008) of pixel-level
resolution data of numerous geophysical parameters over the global ice-free oceans.
Amongst others, these include wind speed (u), near-surface specific humidity (q),
and sea surface temperature (SST). Their uncertainties essentially contribute to
the uncertainty in latent heat flux (LHF) and consequently to that of evaporation
(E).
Here, we will present HOAPS-3.2 pixel-level total uncertainty estimates of evaporation,
based on a full error propagation of uncertainties in u, q, and SST. Both systematic and
random uncertainty components are derived on the basis of collocated match-ups of satellite
pixels, selected buoys, and ship records. The in-situ data is restricted to 1995 until 2008 and
is provided by the Seewetteramt Hamburg as well as ICOADS Version 2.5 (Woodruff et al.
(2011)).
Apart from focusing on spatial uncertainty hotspots, we will furthermore highlight the
necessity of correcting the random error components with respect to collocation
and in-situ uncertainties. The latter procedure is predicated on triple collocation
analysis following O’Carroll et al. (2008), which allows for an error decomposition
to isolate the satellite-based uncertainties from those owing to the methodology. |
|
|
|
|
|