Summary of the GHRSST Joint Workshop Melbourne discussion on the Argo near- surface temperature measurements Andrea Kaiser-Weiss, Gary Wick, Carol-Anne Clayson, Sandra Castro 1 Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

GHRSST XII Edinburgh 2011: “The near-surface measurements from Argo profiling floats provide a new data set that is highly valuable for independent validation of SST retrievals, models and analyses. Thus the GHRSST Science Team recommends that these data are reserved for independent validation.“ Melbourne Workshop 2012: “GHRSST would use as many as near-surface profiles as possible, both pumped and un-pumped, with a vertical resolution as high as possible. There is value in detecting near-surface temperature profiles, even if the absolute accuracy might be degraded.” 2 Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

Diurnal warming effects W m -2 June 1, 2006 Diurnal warming (DW) impacts convection as well as heat and moisture fluxes on a seasonal – intra- seasonal (MJO, ENSO) and climate scale. Model parameterisation for DW is required as physics are not resolved. The likelihood of Argo floats observing DW is much higher than that of dedicated short-term measurement campaigns. 3Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

Modelled (deeper) diurnal warm layers to be verified with Argo: afternoon temperature profiles light winds (3.0 m/s) Modelled Diurnal Warming: 4Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

Coloured profiles show evolution over 6 hours Calm winds (0.5 m/s) Modelled (shallow) diurnal warm layers to be verified by Argo: There are almost no in situ measurements covering significant warming cases, i.e., in excess of 3K. Modelled Diurnal Warming: 5Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

Validation of GHRSST Level 4 products GHRSST L4 foundation SST are not directly observed by satellites. Argo NST profiles could potentially provide independent verification. Foundation temperature anomaly against climatological mean (GHRSST Multi-Product Ensemble, copyright UK Metoffice). Current studies suggesting value of Argo NST – more data close to surface would significantly increase this value. 6Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

Accuracy Accuracy requirement for learning more about diurnal warming is not stringent. The vertical resolution would be required as high as possible. Sensor uncertainties can be dealt with by normalizing with the surface pressure reading. Previous studies (Steve Riser, Jon Turton) suggest that the accuracy of the un-pumped data is sufficient for our requirements. 7 Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012

GHRSST use of Argo NST GHRSST would use (1) continuously pumped measurements and (2) un-pumped measurements, from 10m to as close to the surface as possible and with a vertical resolution as high as possible. Expected benefits from the global coverage and the significant sample of profiles Argo could provide: Parametrization of diurnal warming models, verification of satellite observations of diurnal warming Independent verification of SST foundation (GHRSST L4 products) Determination of stability of climate data records 8Joint Workshop on Tropical Warm Pool and High Latitude SST Issues, Melbourne, Australia 5 – 9 March 2012