Abstract
Abstract. Linear temporal trends in cloud fraction over the extratropical oceans, observed by NASA's Multi-angle Imaging SpectroRadiometer (MISR) during the period from 2000 to 2013, are examined in the context of coincident European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data using a maximum covariance analysis. Changes in specific cloud types defined with respect to cloud-top height and cloud optical depth are related to trends in reanalysis variables. A pattern of reduced high-altitude optically thick cloud and increased low-altitude cloud of moderate optical depth is found to be associated with increased temperatures, geopotential heights, and anti-cyclonic flow over the extratropical oceans. These and other trends in cloud occurrence are shown to be correlated with changes in the El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the North Pacific index (NPI), and the Southern Annular Mode (SAM).
Highlights
Clouds play a fundamental role in Earth’s climate due to their effect on the planet’s radiative budget
Cloud fraction trends in each of the ocean basins shown in Fig. 1 are discussed in terms of the maximum covariance analysis (MCA) decomposition for that basin
We examine the time series associated with these two MCA modes and the Pacific–North American (PNA), Pacific Decadal Oscillation (PDO), and North Pacific index (NPI) in Fig. 5a and b
Summary
Clouds play a fundamental role in Earth’s climate due to their effect on the planet’s radiative budget. Marchand: Cloud responses to climate variability over the extratropical oceans to identify subtle changes in cloud fraction, especially for particular cloud types Authors of these previous studies recognized and used various approaches to account for limitations of the data (Evan et al, 2007; Bender et al, 2011; Norris and Evan, 2015). Marchand (2013) found that both the Multi-angle Imaging SpectroRadiometer (MISR) and the MODerate resolution Imaging Spectroradiometer (MODIS) data sets contain linear temporal trends in cloud fraction (for specific cloud types) in various regions between 2000 and 2010 These trends include (a) a decrease in mid-level clouds over the Southern Ocean (30–50◦ S and strongest over the South Pacific), (b) a decrease in high-level clouds and increase in low-level clouds over the North Pacific, and (c) an increase in cloud of moderate optical depth (1.3 < OD < 23) and an approximately compensatory reduction in cloud of high optical depth (OD > 23) over the extratropical oceans of both hemispheres. We examine correlations with known modes of climatic variability including the El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the SAM
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
