Satellite climatology of cloud liquid water path over the Southeast Pacific between 2002 and 2009

Abstract. Spatial and temporal variability of liquid water path (LWP) over the southeast Pacific is described using LWP observations made by four satellite microwave radiometers (Advanced Microwave Scanning Radiometer on EOS-Aqua (AMSR-E), Tropical Rainfall Measuring Mission Microwave Imager (TMI), and the Special Sensor Microwave Imager (SSM/I) F13 and F15 satellites) for the 7-yr period June 2002–May 2009. This study quantifies seasonal and interannual variability of the LWP and LWP diurnal and semi-diurnal cycles at 30-day intervals during the 7-yr analysis period. The LWP field shows considerable spatial and seasonal variability throughout the southeast Pacific, particularly associated with the southern branch of the Intertropical Convergence Zone (SITCZ) and the Southeast Pacific Convergence Zone (SPCZ). Two distinct annual cycles of LWP are apparent, both of which peak during the austral autumn. One is associated with an active phase of the SITCZ, while the other is associated with increased LWP in the SITCZ, SPCZ, and near coastal zones, and decreased LWP elsewhere. Consistent with previous observations, the LWP diurnal cycle peaks during the early morning and has the largest amplitude in a broad region near 85° W, 20° S. The amplitude of the LWP diurnal cycle exhibits a strong annual cycle which peaks during the austral summer. A secondary annual cycle in the LWP diurnal cycle amplitude peaks during the austral autumn south of 20° S and is a minimum within a zonal band between 8° S and 20° S. Finally, although this satellite combination barely resolves semi-diurnal LWP variability, it is shown that a statistically significant semi-diurnal cycle of LWP occurs off Peru and northern Chile, consistent with previous analyses. The amplitude of the LWP semidiurnal cycle tends to peak during the austral spring.