SUPPLEMENTAL FIGURES
Fig. S1. The annual mean MODIS cloud fraction after applying the 87% threshold filter (shading) and
the contours of the annual mixed phase and ice cloud frequency (%) for each region.
Fig. S2. Mean merged-IR total cloud fraction (left column), MODIS total cloud fraction without the
transfer standard applied (center column), and the difference between the two (IR – MODIS; right
column) at night in the (top row) NE Pacific, (middle row) SE Pacific, and (bottom row) SE Atlantic.
Data were aggregated from approximately 5000 MODIS overpasses from 2003-2010. The merged-IR
data were taken from the 30-min scene closest to each MODIS nighttime (~2230 and 0130 LT)
overpass. The solid lines in the left and center columns delineate the regions of merged-IR data that
do not contain an obvious zenith angle correction error and where MODIS cloud top temperatures
colder than 273 K occur less than 35% of the time. In the right column black lines outline the areas
used in our quantitative analyses. This is the same as Fig. 11 in the paper except using unfiltered
MODIS cloud fraction data.
Fig. S3. As in Fig. S2 except for the MODIS daytime (~1130 and 1330 LT) overpasses. This is the
same as Fig. 12 in the paper except using unfiltered MODIS cloud fraction data.
Fig. S4. NE Pacific - The mean cloud fraction during the night (left column), during the day (center
column), and the difference between the two (right column). In the top row we show the MODIS cloud
fractions without applying the 87% transfer standard, the middle row is the MODIS cloud fractions
after applying the transfer standard, and the bottom row is the merged-IR cloud fractions.
Fig. S5. As in Fig. S4 except for in the SE Pacific.
Fig. S6. As in Fig. S4 except for in the SE Atlantic.
Fig. S7. NE Pacific - The mean MODIS (top row) and merged-IR (bottom row) total cloud fraction for
each of the four seasons (columns). MODIS pixels with fractional cloudiness greater than 0.87 are
classified as cloud in the raw MODIS swaths before calculating cloud fraction to create a more direct
comparison. The merged-IR data is taken only from times of a corresponding MODIS overpass. The
solid line indicates regions of merged-IR data without the zenith angle correction error and where
cloud top temperatures colder than 273 K occur less than 35% of the time.
Fig. S8. As in Fig. S7 except for in the SE Pacific.
Fig. S9. As in Fig. S7 except for in the SE Atlantic.
Fig. S10. NE Pacific - (left column) The season in which the highest seasonal mean cloud fraction
occurred, (center column) the season in which the lowest seasonal mean cloud fraction occurred, and
(right column) the difference in mean cloud fraction between the maximum and minimum seasons.
Results found using the filtered MODIS cloud fractions are in the top row while results found using the
merged-IR cloud fractions are in the bottom row.
Fig. S11. As in Fig. S10 except for in the SE Pacific.
Fig. S12. As in Fig. S10 except for in the SE Atlantic.
Fig. S13. NE Pacific - (top row) The seasonal mean merged-IR cloud fraction and (bottom row) the
amplitude of the diurnal cycle for each season.
Fig. S14. As in Fig. S13 except for in the SE Pacific.
Fig. S15. As in Fig. S13 except for in the SE Atlantic.
Fig. S16. NE Pacific - Distributions of cloud fraction (y-axis) during the daylight hours conditioned on
cloud fraction at dawn (0500-0600 LT) for the maximum (top row; Mar-Apr-May) and minimum
(bottom row; Sep-Oct-Nov) cloudiness season. Distributions of mean cloud fractions are shown for 3h time windows. Starting dawn cloud fractions are: (far left column) greater than 95%, (center left
column) between 75-95%, (center right column) between 50-75%, and (far right column) less than
50%. For each distribution, the filled circle shows the mean value and the open square shows the
median value. Total sample size (N) and sample fraction (%) are given in each panel. In some places
the plots are blank due to a lack of samples with which to create a distribution.
Fig. S17. As in Fig. S16 except for in the SE Pacific where the maximum cloudiness season is SepOct-Nov and the minimum cloudiness season is Dec-Jan-Feb.
Fig. S18. As in Fig. S16 except for in the SE Atlantic where the maximum cloudiness season is SepOct-Nov and the minimum cloudiness season is Mar-Apr-May.
ANIMATIONS
“Max_Season_Diurnal_Cycle_of_Cloud_Fraction.mp4”
Hourly mean merged-IR cloud fraction across the diurnal cycle during the maximum cloudiness
season in the (upper left) NE Pacific [Mar-Apr-May], (lower left) SE Pacific [Sep-Oct-Nov], and (lower
right) SE Atlantic [Sep-Oct-Nov]. The local solar time for each 1-h window is indicated in the upper
right corner of the figure. Data were aggregated from 2003-2010 and each 1-h period contains
approximately 1500 scenes.
“Min_Season_Diurnal_Cycle_of_Cloud_Fraction.mp4”
Hourly mean merged-IR cloud fraction across the diurnal cycle during the minimum cloudiness
season in the (upper left) NE Pacific [Sep-Oct-Nov], (lower left) SE Pacific [Dec-Jan-Feb], and (lower
right) SE Atlantic [Mar-Apr-May]. The local solar time for each 1-h window is indicated in the upper
right corner of the figure. Data were aggregated from 2003-2010 and each 1-h period contains
approximately 1500 scenes.
“SEP_Maps_yyyymmdd_hhmm_to_ yyyymmdd_hhmm _UTC.mp4”
Animations of the (left column) merged-IR brightness temperature, (center column) cloud mask
derived using our IR-based methodology, and (right column) the GOES visible albedo in the SE
Pacific. Animations span across the times given in the movie name and the time for each frame in the
movie is indicated in the bottom center column.