Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites

Abstract

The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched aboard the Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. A comprehensive set of remote sensing algorithms for the retrieval of cloud physical and optical properties have enabled over twelve years of continuous observations of cloud properties from Terra and over nine years from Aqua. The archived products from these algorithms include 1 km pixel-level (Level-2) and global gridded Level-3 products. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. Results include the latitudinal distribution of cloud optical and radiative properties for both liquid water and ice clouds, as well as latitudinal distributions of cloud top pressure and cloud top temperature. MODIS finds the cloud fraction, as derived by the cloud mask, is nearly identical during the day and night, with only modest diurnal variation. Globally, the cloud fraction derived by the MODIS cloud mask is ~67%, with somewhat more clouds over land during the afternoon and less clouds over ocean in the afternoon, with very little difference in global cloud cover between Terra and Aqua. Overall, cloud fraction over land is ~55%, with a distinctive seasonal cycle, whereas the ocean cloudiness is much higher, around 72%, with much reduced seasonal variation. Cloud top pressure and temperature have distinct spatial and temporal patterns, and clearly reflect our understanding of the global cloud distribution. High clouds are especially prevalent over the northern hemisphere continents between 30° and 50°. Aqua and Terra have comparable zonal cloud top pressures, with Aqua having somewhat higher clouds (cloud top pressures lower by 100 hPa) over land due to afternoon deep convection. The coldest cloud tops (colder than 230 K) generally occur over Antarctica and the high clouds in the tropics (ITCZ and the deep convective clouds over the western tropical Pacific and Indian sub-continent). The cold clouds over the Sahara, though infrequent, are generally high, thin cirrus.The cloud effective particle radius of liquid water clouds is significantly larger over ocean (mode 12-13 µm) than land (mode 10-11 µm), consistent with the variation in hydroscopic aerosol concentrations that provide cloud condensation nuclei necessary for cloud formation. We also find the effective radius to be 2-3 µm larger in the southern hemisphere than the northern hemisphere, likely reflecting differences in sources of cloud condensation nuclei.

Measurement Performance Assessment of Future Space-Borne Doppler Wind Lidar for Numerical Weather Prediction

“…It is important to discuss the seasonal dependency of our results. For example, CALIOP data show seasonal and geographical features of aerosol loads (Winker et al 2013), and MODIS also suggest seasonal and terrestrial contrasts of cloud fraction (King et al 2013). The measurement performance related to SNR can vary with the aerosol concentration and the probability of occurrence of clouds.…”

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

“…The r ei is retrieved for the same sample although retrievals with QC = 2 are not included. Kahn et al (2015) describe pixel-level comparisons between AIRS and MODIS ice cloud properties and show that overlapping sensitivity for both τ i and r ei is observed for optically thicker pixels containing four positive ice phase tests with spatial maps resembling those described in King et al (2013).…”

“…The well-documented (Wylie et al, 2005;King et al, 2013;Stubenrauch et al, 2013) spatial distributions of ice clouds with maxima in the tropics and extratropical storm tracks and minima in the subtropical gyres are shown in Fig. 1.…”

Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 2: Variability and characteristic differences under near-pristine, biomass burning, and long-range transport conditions

“…The obtained Aqua and Terra time series were averaged. Note that cloud cover strongly depends on the spatial resolution of the instrument as outlined in King et al (2013).…”

“…-Cloud droplet effective radius, re, is calculated from the products measured from the MODIS instrument on Since re varies with vertical cloud development and total CCN abundance, we filtered the re data by cloud top temperature (King et al, 2013). …”