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Moisture Interchange between Clouds and Environment
in a Tropical Atmosphere
Carlos S. López Carrillo
Submitted in Partial Fulfillment of the Requirements
for the Degree of
Doctor of Philosophy
New Mexico Tech
Socorro, New Mexico
To Julieta, Lucio, and Damián
The best children no father could have.
In this work a theory for moisture interchange between
cloud systems and their environment in the tropical atmosphere is developed.
Data collected during the intensive operation period of TOGA-COARE
(Tropical Ocean and Global Atmosphere-Coupled Ocean-Atmosphere Response
Experiment) is then used to study, on a case-by-case basis, the nature
of this interchange for different convective regimes.
The kinematic characteristics of the studied systems for each of the
ten cases are synthesized from Doppler measurements made by the two
National Oceanic and Atmospheric Administration WP-3D aircraft, while
the environmental conditions were retrieved from balloon soundings made
nearby the studied region.
For this ten-case sample, a strong correlation between system-top height and
tropospheric moisture (in the layer between 1 and 10 km) is found.
The analysis indicates that it is tropospheric moisture which is
controlling the height of the clouds and not vice-versa. It is found
that the role of small clouds is to moisten the environment while deep
convective regimes dry their environment.
At the end of the long period of time, that the making of a
dissertation spans, it is good to look
back and see the team of people that had helped you, so you can
accomplish this goal. It is good to know that one is not alone.
At this point, I would like to thank some of the many people that had
helping me in various ways.
I want to thank the guidance and support that I received
from my adviser Dr. David J. Raymond, who expended with me many hours
discussing how convection works in general, and in particular over
the tropical regions. I also want to thank the confidence deposited
in me by Dr. Odon Sanchez, who first told me about the research
opportunities in atmospheric sciences, and for his support that
allow me to pursue further graduate studies in this area.
I'm grateful to the members of my committee: Drs. Kenneth R.
Mischwaner, Steve Schaffer, and Ken Eack for their prompt
review of the manuscript and the suggestions they made to
improve it. I particularly want to thank my fellow student
Clifton Murray for proof reading the many versions of the manuscript,
which considerably improved the way it was written.
Special thanks goes to Sandy Kieft whose mastery and efficiency of
administrative matters, took lots of worries from my head.
A good part of this work could not be possible with out
the data provided by John Daugherty from NOAA/NSSL.
Most of the data analysis was made using the in-house
CANDIS software pioneered by David J. Raymond and further
developed by many students here at New Mexico Tech. I also
benefited from powerful packages such as Rlab
by Ian Searle, and Gri by Dan E. Kelley. All my work was done on
a Linux-debian platform.
I especially want to thank my source of continuous inspiration
since I remember - my mother, who instilled in me her strong
work ethic. My children, I have to thank no only for being a
source of inspiration for me, but also for being so patient with me
and give up much of our precious time together.
From all people that had helped me, there is one for who
I can hardly express my gratitude, for supporting me
in so many ways, for being the source of energy and joy that
keep me going ... Thank You, Chata - my wife.
This work was supported by the following National Science
ATM-9311735, ATM-9413289, ATM-9616290, and ATM-0082612.
- List of Figures
- List of Tables
- Part : Introduction
- I. Fundamental Equations
- 1. Multicomponent fluids
- 2. Standard techniques
- 2.1 Budget balance
- 2.2 Standard fixed-control-volume technique
- 3. Governing equations
- 3.1 Mass Continuity
- 3.2 Dry air
- 3.3 Individual components of water substance
- 3.4 Total water substance
- 3.5 Total Mass
- 3.6 Linear Momentum equation
- 3.7 Total energy equation
- 3.8 Entropy
- 4. Explicit relationships
- 4.1 Internal energy
- 4.2 Kinetic energy
- 4.3 Potential energy
- 4.4 Bernoulli function
- 4.5 Entropy
- 5. Tendency equations
- 5.1 Water substance
- 5.2 Total energy tendency
- 5.3 Entropy tendency
- 5.4 Getting rid of precipitation
- 6. Moistening and drying tendency equations
- II. Data Analysis &
- 7. Data Sources
- 8. Soundings
- 9. Mass Fluxes
- 10. System Top and Tropospheric Moisture
- 11. Lateral Export
- Part : Conclusion
- A. Clear air sounding profiles
- A.1 Moist energy
- A.2 Moist Bernoulli function
- A.3 Moist entropy
- A.4 Measurement Error
- B. Radar observations
- B.1 Radar measurements in meteorology
- B.2 Doppler Radar measurements
- B.3 Airborne Doppler Radar
- B.3.1 Scanning strategy -- FAST
- B.3.2 Trajectory strategies
- B.4 Wind field synthesis
- C. Covariance Calculations
- D. Divergence - Column Correction
List of Figures
- Sketch of a typical control volume used in this work.
- This figure shows the area studied during field phase of TOGA-COARE...
- Relative location between sounding and the aircraft target area
for the case of January 16, 1993. The system was moving toward the
east. The background shading is the infrared brightness temperature
from the GMS-4 Japanese satellite taken at 2315 UTC. Infrared
temperatures are in degrees Celsius. The dashed polygon represents
the intensive flux array(IFA), while the target area is enclosed by
the rectangle. The aircraft path (thin-solid line) reached the target
area approximately at 2300 UTC. The sounding was launched at 2302 UTC
by the Shiyan 3 (solid diamond at the most right corner of the
IFA and ahead of the system).
- Interpolation grid for the cases presented here. The vertical
height is always 20 km and the horizontal dimensions vary from
case to to case in order to acomodate all radar data collected
during the period of interest.
- Histogram of Cartesian speeds for the case of December 15, 1992.
This case corresponds to a deep convective system. All speeds
from grid points where large geometrical errors (greater than 1
- see text) were not included in the histogram.
- This figure shows the average vertical mass flux for the ten
case studies examined here. They are grouped according to
environmental moisture and cloud top height. Cases on the left
panel correspond to small systems in dry environments. Tall
systems in dry environments are in the central panel while tall
systems in a moist environment are in the right panel.
- Vertical variation of the saturation deficits defined as the
differences between saturated and environmental moist energy
(left), moist entropy (center), and specific humidity (right),
for all missions in this study.
- Correlation between system-top height and three measures of
tropospheric moisture: In the left panel the moisture is represented
by the moist-energy saturation deficit, in the central by the
moist-entropy saturation deficit, and in the right by the
specific-humidity saturation deficit. In each case the saturation
deficit is average over a layer extending from 1 to 10 km. The
corresponding correlation coefficients for each case are given at
the top of each panel.
- Average detrained mass flux for the ten case studies examined
here, grouped according to environmental moisture and cloud top
height. Cases in the left panel correspond to small systems in dry
environments. Tall systems in dry environments are in the central
panel; deep systems in a moist environment are in the right panel.
- Sketch of a radar ray showing one gate.
- Range-ambiguous echos. The nth transmitted pulse and its echos
are crosshatched. This example assumes that the larger echo at delay
is unambiguous in range but the smaller echo, at delay ...
(Figure taken from, Doviak (1984), pg. 45])
- Signals at three different Doppler frequencies that yield ,
when sampled, the same set of data. These Doppler frequencies are
aliases of each other.(figure taken from, Doviak (1984) pg. 45])
- Fore/Aft scanning technique (FAST)
- Horizontal pseudo-dual Doppler coverage for tail Doppler
radar using the fore/aft scanning technique(FAST).
- Examples of aircraft trajectories used during TOGA-COARE
to survey convective systems. Panel (a) shows a so-called ``stack''
flown by WP3-42 on February 1, 1993. Panel (b) shows part of the
mission flown by WP3-43 (dashed) and WP3-42 (solid) on December
12, 1992. The segments were time-coordinated to allow for a more
dense sampling. This sampling geometry performed by two aircraft
in FAST mode is called quad-Doppler.
- Radial velocity measurements inside a grid volume. The spheres
represent radar-sample volumes (i.e. gates). Arrows at the corners
represent the interpolated wind velocities.
- Horizontal wind velocities assuming zero vertical particle
velocity for the case of December 15, 1992, surveyed by the WP3-42
during TOGA-COARE. The velocities are Earth-relative, but they are
shown in the storm reference frame.
(a) All velocities inferred.
(b) Locations where the amplification factors are bigger than 1.
(c) Velocities associated with the locations shown in panel (b).
(d) Velocities that remain after thresholding out points where the
amplification factors are larger than one.
List of Tables
- Information about the data sources used in this work.
The following are the meanings of the labels.
BS = Balloon sounding: SH = R/V Shiyan 3 ;
MW = R/V Moana Wave ; XY = R/V Xiangyanghong 5 ;
KP = Kapingamarangi. ACR = radar data:
BWP means both WP-3D aircraft. AD = Average distance between
soundings and aircraft target area.
LT = Balloon launching time;
RTI = selected time intervals for Doppler analysis in each mission.
The Cartesian components of the system velocity were calculated from
the values reported in, Kingsmill and Houze (1999)] - they are positive
in the east and north directions.
- The constants in this table were arbitrarily chosen. Other
constants used but not listed here, such as the latent heat at the
reference points and the heat capacities, were taken from, Emanuel (1994).
- Ttop is the temperature at the top of the control cylinder ....
- For each mission, the moisture in the environment is estimated using
sounding data ...
- The first column shows the layer over which the
average of the corresponding saturation deficit was taken. The rest of
the columns show the correlation coefficient for each correlation.
- Convective contributions to the budgets of moist energy (ME) and moist
entropy (MS), respectively. The implied role of the convective system over
its environment according to the analysis presented in chapter is also listed.
Carlos Lopez Carrillo