A study on the low-altitude clouds over the Southern Ocean using the DARDAR-MASK

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Huang, Yi, Siems, Steven T., Manton, Michael J., Protat, Alain, Delanoë, Julien
• Other Authors: Monash Weather and Climate (MWAC), Monash University Clayton, Centre for Australian Weather and Climate Research (CAWCR), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2012
• Subjects: DARDAR-MASK; Clouds; SO; MODIS; A-train; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Southern Ocean; Austral
• Online Access: https://hal.science/hal-00724011; https://hal.science/hal-00724011/document; https://hal.science/hal-00724011/file/2012JD017800.pdf; https://doi.org/10.1029/2012JD017800

International audience A climatology of the thermodynamic phase of the clouds over the Southern Ocean (40-65S,100-160E) has been constructed with the A-Train merged data product DARDAR-MASK for the four-year period 2006-2009 during Austral winter and summer. Low-elevation clouds with little seasonal cycle dominate this climatology, with the cloud-tops commonly found at heights less than 1km. Such clouds are problematic for the DARDAR-MASK in that the Cloud Profiling Radar (CPR) of CloudSat is unable to distinguish returns from the lowest four bins (heights up to 720 - 960m), and the CALIOP lidar of CALIPSO may suffer from heavy extinction. The CPR is further limited for all of the low-altitude clouds (tops below 3km) as they are predominantly in the temperature range from freezing to -20 C, where understanding the CPR reflectivity becomes difficult due to the unknown thermodynamic phase. These shortcomings are seen to flow through to the merged CloudSat-CALIPSO product. A cloud-top phase climatology comparison has been made between CALIPSO, the DARDAR-MASK and MODIS. All three products highlight the extensive presence of supercooled liquid water over the Southern Ocean, particularly during summer. The DARDAR-MASK recorded substantially more ice at cloud-tops as well as mixed phase in the low-elevation cloud-tops in comparison to CALIPSO and MODIS. Moving beneath the cloud-top, the DARDAR-MASK finds ice to be dominant at heights greater than 1 km, once the lidar signal is attenuated. The limitations demonstrated in this study highlight the enormous challenge that remains in better defining the energy and water budget over the Southern Ocean.