Atlantic Tropical Studies
and airborne sampling strategies
Advantages of Caribbean Location for Studying
Clouds and their interactions with Dust
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Tropical maritime convective clouds are less complex to study than
convective clouds found over mid latitudes and the continents. They have
less day-to-day variations in stability, wind shear, cloud base height, etc.
The Caribbean is subject to regular episodic incursions of dust from Africa,
which provides an injection of suspected ice nuclei—an ideal natural
experiment to test the effects of dust on the development of precipitation.
The Caribbean provides access to a wide range of tropical clouds of different
sizes, including tropical cyclones, an important class of storms for which ice
formation is of interest.
The maritime environment of the Caribbean, during non dust events, is
similar to many other tropical maritime regions, so the results will have
application to our understanding of maritime tropical storms, which are of
particular interest to understanding climate.
Tropical convection is less of a concern for aircraft safety. Tropical
convection in the temperatures of interest (+5 to -30) is less likely to contain
hail or hazardous updrafts and downdrafts that are a major concern for
aircraft safety, compared to storms found in mid latitude continental
locations.
The RICO project (December—Januray 2004-5) will have provided logistic
experience in this area (Antigua).
Monthly Mean Dust Aerosol mass
concentration (ug m-3)
Dust Climatology from Africa is pretty well documented.
18.00
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
Jan
Feb
Mar
Apr
May Jun
Jul
Aug Sep
Oct
Nov Dec
Monthly mean dust aerosol concentrations at Miami, 1989-1996. From Prospero,
J.M., 1999: Long-term measurements of the transport of African mineral dust to the
southeastern United States: Implications for regional air quality. JGR Vol 104, No
D13, 15917-15927.
Some objectives of an ice study in
the tropical-subtropical Atlantic
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Document microphysical structure
of clouds in dusty and non dusty
conditions
Follow ice development in tops of
growing cu.
Document profiles of liquid water
and examine relationship with
updraft, entrainment, ice
characteristics, temperature, etc.
Evaluate the importance of RimeSplintering vs primary ice
Fill in missing gaps in Hurricane
microphysics
Example of possible individual cloud sampling strategy
In cloud leg
Radar+Lidar Leg
In cloud leg
Radar+Lidar Leg
One-aircraft, example of Radar+ in situ sampling.
Hurricane Penetrations
• Strong storms:
Sample outer
rainbands at various
altitudes (-5 to -25 C),
working part way
towards core
• Sample weaker,
organized regions
associated with
easterly waves, below
hurricane strength.
Possibilities
• Share same set of airborne instruments for
Atlantic or Pacific Dust/Cloud study
• Region of interest is within 1 day of Boulder (e.g.
Boulder to Hawaii, or Boulder to Antigua)
– Need plume mapping strategy
– Tie airborne sampling in with model predictions 24 hrs
in advance (flight guidance and model validation)
– Possible cross region flight (e.g. Antigua to Cape
Verde) with 1 to 3 hours sampling deviation
(depending on altitude). Use endpoints or midpoints
(e.g. Midway) as possible regions of interest in certain
plume conditions.