Effects of ship wakes on ocean brightness and radiative forcing over ocean

• Published in: Geophysical research letters 2011-09, Vol.38 (17), p.n/a
• Main Authors: Gatebe, C. K., Wilcox, E., Poudyal, R., Wang, J.
• Format: Article
• Language: English
• Subjects: Aerodynamics; aircraft; Albedo; ARCTAS; Atmospheric sciences; bidirectional reflectance distribution function (BRDF); Climate; Climate change; Cloud Absorption Radiometer (CAR); Coastal zone; Earth; Earth sciences; Earth, ocean, space; Economics; Exact sciences and technology; Globalization; Greenhouse gases; Harbors; Human influences; Intergovernmental Panel on Climate Change; ocean albedo; Oceans; Radiation; Radiation measurement; Radiative forcing; Remote sensing; Scientific apparatus & instruments; Ships; Wakes
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2011GL048819

Changes in surface albedo represent one of the main forcing agents that can counteract, to some extent, the positive forcing from increasing greenhouse gas concentrations. Here, we report on enhanced ocean reflectance from ship wakes over the Pacific Ocean near the California coast, where we determined, based on airborne radiation measurements that ship wakes can increase reflected sunlight by more than 100%. We assessed the importance of this increase to climate forcing, where we estimated the global radiative forcing of ship wakes to be −(0.14 ± 50%) mWm−2 assuming a global distribution of 32331 ships of size ≥100000 gross tonnage. The forcing is smaller than the forcing of aircraft contrails (−0.007 to +0.02 Wm−2), but considering that the global shipping fleet has rapidly grown in the last five decades and this trend is likely to continue because of the need of more inter‐continental transportation as a result of economic globalization, we argue that the radiative forcing of wakes is expected to be increasingly important especially in harbors and coastal regions. Key Points Unique angular spectral radiance measurements of ship wake Albedo change caused by moving ships could have a bearing on climate forcing Human influence on ocean albedo is neglected in the current IPCC assessments