Transcript A Real-Time Analysis of Daily Precipitation Over South Asia

Diurnal Cycle
of Cloud and Precipitation Associated
with
the North American Monsoon System
Pingping Xie,
Yelena Yarosh, Mingyue Chen,
Robert Joyce, John Janowiak, and Phillip A. Arkin
Objective:
 To
examine the diurnal cycle of
cloudiness and precipitation
over the NAME domain using
the GOES IR and CMORPH
precipitation data
Target Area and Period:
Target Area:
•
Mexico
22oN – 32oN;
(circulation patterns south of 22oN seem different)
Target Period:
•
Warm Season 2003
May 1 – Oct. 31, 2003
Precipitation Data:
 CMORPH (Joyce et al. 2004)
 Precipitation estimates based on
satellite observations;
 Original CMORPH data produced on
a resolution of 30-min / 8-km over the
globe;
 3-hourly mean precipitation calculated
on 0.25o lat/lon grid in this work;
Cloudiness Data [1]:
 GOES Full Resolution IR data
(Janowiak et al. 2001);
 Surface / cloud top temperature on a
resolution of 30-min / 4-km;
 Fractional coverage of clouds colder
than 215K, 235K, and 255K is
calculated on a resolution of 3-hourly /
0.25o lat/lon;
Cloudiness Data [2]:
 Clouds are classified into 3 kinds for
convenience purpose:
 Low Clouds:
 Middle Clouds:
 High Clouds:
255K – 235K
235K – 215K
<215K
 Cloudiness is shown in percentage (%).
Mean Precipitation and Topography
Heavy rainfall is
observed over
both the west and
east coasts of
Mexico
Mean Precipitation and Cloudiness
Low
Clouds
Middle
Clouds
High
Clouds
Precip.
[mm/day]
Clouds have wider and smooth distribution than precipitation;
There is an east-west shift in the maximum positions;
3-Hourly Mean Precipitation

Precipitation starts
at morning time;
 It reaches
maximum in late
afternoon;
 Diurnal cycle over
the west and east
coasts is in phase;
3-Hourly Mean Low Clouds [235K-255K]

The maximum
amount of low
clouds appears ~3
hours later than that
for the precipitation
3-Hourly Mean Mid Clouds [215K-235K]

The diurnal cycle
of middle and high
clouds is basically
in phase with that
of the
precipitation;
Diurnal Cycle of Cloudiness and
Precipitation Relative to the Mountain


Mean values are calculated
over a latitude band 22oN –
32oN, relative to the
mountain ridge;
Cloud / precip. Starts over
high elevation in the
morning, moves toward
coast as it reaches
maximum;
 High clouds are located
over west of low clouds
Mean Diurnal

[22oN-32oN; 5o W/E to the Ridge]
Diurnal cycle of low clouds has a flatter tail than
that for the high/middle clouds and the precip.
Summary:
 Cloud
and precipitation start from higher
elevation in the morning, move toward the
coast as they reach the maximum in late
afternoon;
 The
position of maximum higher clouds is
located west to that for the lower clouds;
 All
data used here are available to NAME
scientists;
Future Work:

Differences in diurnal cycle for different months in
a monsoon season;
 Year-to-year variations;
 Diurnal cycle for regions south of 22oN;
 3-D structure of diurnal cycle of precipitation
using TRMM data;
 Connection to large-scale circulation patterns of
intraseasonal to interannual time scales;
 Relation to findings by other NAME scientists;
3-Hourly Mean Amount of High Clouds
East-West Section
of Mean cloudiness / Precipitation