CloudSat views the Asian
summer monsoon
an opportunistic data celebration
Brian Mapes
University of Miami
CloudSat
 3 mm wavelength radar, nadir pointing
– Sees cloud and precipitation
 attenuation in heavy rain
 5 mm/h obscures surface
 Nadir “curtain” sampling
– Vertical (range) sampling 250m
– Horizontal (along track) sampling 1.1 km
– Twice daily (1am, 1pm local time)
 Flying since June 2006
– here examine JJAS 2006 data in Asian region
CloudSat and the A-Train
CloudSat measurements
within a few minutes of all
other A-train observations
Opportunism
 spotty / sparse sampling
(nadir ‘curtain’ only)
 Encourages unbiased (whole
dataset !) analysis
 1pm and 1am LST only
 Part of the A-train
 radar reflectivity is a hard
to interpret physical
measurement
 Rich in information accurate, large dynamic
range - retrievals will come
 Attenuation; surface clutter
issues at low levels
 FIRST global profiles !!!
Cloud top is best meas.
Cloud tops >1km are fine.
CloudSat – Measured Return Power
Cloud Mask (20-40 = “yes”)
cloud
This analysis based on cloud objects
 A contiguous region (in the vertical slice) where
cloud mask = “yes”
 Each has a bundle of attributes
– mean lat, mean lon, time, top, thickness, width,
lowest and highest altitude of surface underneath,
etc. etc.
 Each is collection of pixels (3-1000’s of
them)
 accessible using cloud ID #
 example (a complicated one):
top
thk = NPIX/width
width
All JJAS 2006 cloud centroids
First condsider
all JJAS 2006
clouds centered in
10-15N, 75-80E
Define 7 tropical cloud object types
 Joint histogram of top height & thickness
– First: all clouds 15N-15S (as a global backdrop)
0 High thin
2 middle
thin
4 low
thin
1 Deep (High Thick)
3 mid-top
Thick
Low top but tall/thick or drizzling
(5: >10km wide) ( 6: <10km wide)
JJAS 2006 day and night clouds over S. India
~ true aspect ratio
20 km layers
day
One night cloud 350 km wide
night
low-dBZ high clouds
Joint
histograms of
pixel-wise
z & dBZ
pos. anomalies
(mean histogram &
more later)
low-dBZ low clouds
high-dbZ (and raining)
middle clouds
Beyond South India
1. ASM pattern & profile of cloud objects
by cloud top altitude
2. Natural cloud “types”
3. Drill down to pixels (z - dBZ joint hists.)
4. Contrasts




ocean - coast - land
lowland - slope - plateau (over E & W Tibet)
day - night
East Asia vs. South Asia (Bin Wang request)
5. Dynamical variations
 MISO from Sep. 2006
JJAS OLR climatology
JJAS OLR climatology
7
3
8
4
1
9
5
6
2
0
JJAS 2006 CloudSat-sampled cloud volume
7
8
3
4
1
9
5
6
2
0
Latitude vs. top-height distribution
whole monsoon (40E-160E)
tropical deep
plateau,
midlat.
midlat.
middle tops
low-top clouds
0 (SH)
1,2 (Eq.)
in subtropics
3,4,5,6
(NIO, SCS, Phil.)
7,8,9
Tibet, E.Asia
JJAS 2006 CloudSat-sampled cover (area)
(S Asia: middle-topped clouds enhanced)
7
3
8
4
1
Lon vs. cloudtop
distribution
9
5
6
2
0
Beyond South India
1. ASM pattern & profile of cloud objects
by cloud object top altitude
2. Natural cloud “types”
3. Drill down to pixels (z - dBZ joint hists.)
4. Contrasts
 ocean - coast - land
 lowland - slope - plateau (over E & W Tibet)
 day - night
5. Dynamical variations
 MISO from Sep. 2006
Joint histogram of top height & thickness
– First: all clouds 15N-15S, Jun06 - Feb07
 (as a global backdrop)
0 High thin
2 middle
thin
4 low
thin
1 Deep (High Thick)
3 mid-top
Thick
Low top but tall/thick or drizzling
(5: >10km wide) ( 6: <10km wide)
Define 7 tropical cloud object types
 Joint histogram of top height & thickness
– First: all clouds 15N-15S (as a global backdrop)
0 High thin
2 middle
thin
4 low
thin
1 Deep (High Thick)
3 mid-top
Thick
Low top but tall/thick or drizzling
(5: >10km wide) ( 6: <10km wide)
Midlevel clouds: a bimodal population
in global tropics
5-6
km
7-8
km
0C
well above melting level...
Monsoon cloud object types
 Joint histogram of top height & thickness
– All 10 monsoon regions pooled, JJAS
0-High layers
2-Middle
layers
4-Low
layers
1-Deep
3-Mid-top
towers
Low top but tall/thick or drizzling
(5: >10km wide) ( 6: <10km wide)
Monsoon cloud object types
 Joint histogram of top height & thickness
– All 10 monsoon regions pooled, JJAS
0-High layers
2-Middle
layers
4-Low
layers
1-Deep
3-Mid-top
towers
Low top but tall/thick or drizzling
(5: >10km wide) ( 6: <10km wide)
7
9
8
Cloud volume
by cloud type
6
2 times of day
(E. India)
(W. India)
3
5
4
Land only
1
am Deep
(W. India)
2
1 convection
1pm
0
7
8
3
1
4
9
5
6
2
0
Beyond South India
1. ASM pattern & profile of cloud objects
by cloud object top altitude
2. Natural cloud object “types”
3. Drill down to pixels (z - dBZ joint hists.)
4. Contrasts
 ocean - coast - land
 lowland - slope - plateau (over E & W Tibet)
 day - night
5. Dynamical variations
 MISO from Sep. 2006
Joint histogram of dBZ and z
all pixels in all JJAS 2006 monsoon clouds
Most frequent cloud: -25 dBZ at 13 km
sensitivity (instrumental)
z (km)
tropopause (a true Earth phenomenon)
Minimum of frequency
in middle of
measurement space
clutter (instrumental)
Reflectivity (dBZe)
rain atten.
multiple scat.
(instrumental)
Integrate over dBZ ->
cloudiness profile
Histogram enhancements associated with
pixels in each of the 7 cloud types
Hightop-thick
Hightop-thin
Heavy rain
attenuates
Lowtop-thin
Midtop-thick
Midtop-thin
rain
Low-thick-wide
rain
Low-thick-narrow Colors show positive
anomalies (relative to
all-monsoon cloud
pool) of normalized
rain
probability density
Beyond South India
1. ASM pattern & profile of cloud objects
by cloud object top altitude
2. Natural cloud object “types”
3. Drill down to pixels (z - dBZ joint hists.)
4. Contrasts
 geographic boxes
 ocean - coast - land
 day - night
5. Dynamical variations
 MISO from Sep. 2006
open contours
all-monsoon mean
7
8
3
Joint Histograms for boxes
4
1
9
5
6
2
0
open contours =
all-monsoon mean
colors =
enhanced normalized frequency
Normalized PD Anomalies >0
7
8
3
4
1
9
5
6
2
0
sea-coast-land in monsoon tropics
(zones 1-6)
Sea
Coast
Land
Day vs. night clouds over land
low-dBZ high clouds
Recall -South India box
low-dBZ low clouds
high-dbZ (and raining)
middle clouds
All day and night clouds over S. India
20 km layers
East Asia
(hT type,
sea, nite)
“more frontal”?
Bin Wang
special
request
BoB
(hT type,
sea, nite)
“more convective”?
EA vs.
tropical
monsoon
seas
Beyond South India
1. ASM pattern & profile of cloud objects
by cloud object top altitude
2. Natural cloud object “types”
3. Drill down to pixels (z - dBZ joint hists.)
4. Contrasts
 geographic boxes
 day - night
5. Dynamical variations
 MISO from Sep. 2006
 compare to BoB Onset 1999 (JASMINE)
Clouds in a monsoon ISO
define a fixed grid on 60-90E OLR time-lat section
1 mo
30N
30N
Sep. 2006
20S
20S
Figure 1: Outgoing Longwave Radiation (OLR),
averaged over 60-90E, contoured in time (15 Jun Π5 Nov) vs.
latitude (20S - 30N) space. Contours at [220, 200, 180] W m-2.
front: 581 clouds,
614954 pixels
Clouds
in front
sorted
by top
height
true
aspect
ratio
Clouds in after category
sorted by top height
after: 296 clouds, 106883 pixels
cf. front: 581 clouds, 614744 pixels
Front vs. After
 Normalized joint
histograms of dBZ
and z of pixels
(log color scale)
Compare to
JASMINE
shipborne
cloud radar
cf. shipborne CPR
sen
May
atten
1999
sen
atten
active
pre-onset
JASMINE
Bay of
Bengal
courtesy P. Zuidema
sum joint histograms for each MISO
phase over dBZ dimension
=>
Cloud fraction profiles across MISO
Cloud Fraction
front
MISO-relative time (3.5 day bins)
after
Dynamical data & deductions
1. ∂/∂t (cloud volume)  ∂/∂p (mass flux) ?
2. CloudSat rad. heating product
3. ECMWF met. interpolated to each pixel
front
MISO-relative time (3.5 day bins)
after
Findings
 CloudSat is good (despite its badnesses)
 Cloud object library is a convenient approach
– can drill down to pixels as needed
 Tropical clouds fall into types (modes of distributions)
 Monsoon clouds are diverse
– low clouds in SIO
– deep convection over tropics
 progressively deeper from Arabian Sea -> BoB -> SCS -> Phil. Sea
– middle clouds enhanced over S. Asian longitudes
 enhanced at night over land, raining
– East Asian clouds (cb systems over sea have lower tops)
 Sep. 2006 MISO cloud structure is tilted
– in an unsurprising manner, but nice to see
Cloud volume distribution in
horizontal size vs. top height space
(all 15N-15S clouds)
7
8
3
4
1
9
5
6
2
0
years since 1-1-2006
One equatorial MJO in
our database so far