CLIVAR/SeaFlux
Description:
This special collection brings together recent research focused on understanding surface fluxes in high latitudes. Many of the papers evolved from presentations at a workshop on High-Latitude Surface Fluxes held in Boulder, Colorado, in March 2010. The workshop was jointly organized by SeaFlux and by the US CLIVAR Working Group on High-Latitude Surface Fluxes, and it was intended to gather a diverse group of researchers including specialists in both open-ocean and ice-covered high latitude regions, specialists in numerical weather prediction and reanalysis, as well as specialists in air-sea surface fluxes. The papers included here span a range of topics, ranging from assessments of the quality of in situ and remotely sensed flux fields in high-latitude regions to studies that consider aspects of the climate system that are affected by surface fluxes. Strong winds, rough seas, and icing conditions can make surface fluxes difficult to measure in high-latitude regions, and many of the studies included here highlight the fundamental challenges that will need to be addressed in order to improve estimates of high-latitude fluxes among ocean, atmosphere, and ice. The articles will be presented below as they are published, and will appear in either the Journal of Climate, the Journal of Physical Oceanography, or the Journal of Atmospheric and Oceanic Technology.
Collection coordinators:
Sarah Gille, Scripps Institution of Oceanography
Mark Bourassa, Florida State University
Carol Anne Clayson, Florida State University
CLIVAR/SeaFlux
Abstract
High-latitude ocean surface air temperature and humidity derived from intersatellite-calibrated High-Resolution Infrared Radiation Sounder (HIRS) measurements are examined. A neural network approach is used to develop retrieval algorithms. HIRS simultaneous nadir overpass observations from high latitudes are used to intercalibrate observations from different satellites. Investigation shows that if HIRS observations were not intercalibrated, then it could lead to intersatellite biases of 1°C in the air temperature and 1–2 g kg−1 in the specific humidity for high-latitude ocean surface retrievals. Using a full year of measurements from a high-latitude moored buoy site as ground truth, the instantaneous (matched within a half-hour) root-mean-square (RMS) errors of HIRS retrievals are 1.50°C for air temperature and 0.86 g kg−1 for specific humidity. Compared to a large set of operational moored and drifting buoys in both northern and southern oceans greater than 50° latitude, the retrieval instantaneous RMS errors are within 2.6°C for air temperature and 1.4 g kg−1 for specific humidity. Compared to 5 yr of International Maritime Meteorological Archive in situ data, the HIRS specific humidity retrievals show less than 0.5 g kg−1 of differences over the majority of northern high-latitude open oceans.
Abstract
High-latitude ocean surface air temperature and humidity derived from intersatellite-calibrated High-Resolution Infrared Radiation Sounder (HIRS) measurements are examined. A neural network approach is used to develop retrieval algorithms. HIRS simultaneous nadir overpass observations from high latitudes are used to intercalibrate observations from different satellites. Investigation shows that if HIRS observations were not intercalibrated, then it could lead to intersatellite biases of 1°C in the air temperature and 1–2 g kg−1 in the specific humidity for high-latitude ocean surface retrievals. Using a full year of measurements from a high-latitude moored buoy site as ground truth, the instantaneous (matched within a half-hour) root-mean-square (RMS) errors of HIRS retrievals are 1.50°C for air temperature and 0.86 g kg−1 for specific humidity. Compared to a large set of operational moored and drifting buoys in both northern and southern oceans greater than 50° latitude, the retrieval instantaneous RMS errors are within 2.6°C for air temperature and 1.4 g kg−1 for specific humidity. Compared to 5 yr of International Maritime Meteorological Archive in situ data, the HIRS specific humidity retrievals show less than 0.5 g kg−1 of differences over the majority of northern high-latitude open oceans.
