APPENDIX B: SYNOPSIS OF SENSING NEEDS, STATE OF KNOWLEDGE,
STRENGTHS, AND WEAKNESSES
SENSING NEEDS
General
Characterization
1. Determine what characteristics of clouds are criti-
1. Good climatologies of icing conditions in all syn-
cal to flight from flight tests, tunnel tests, and nu-
optic situations.
merical models, in a spectrum of meteorological
2. Synoptic, continental, and global icing patterns
conditions from a wide variety of aircraft.
to determine system utility.
2. A meteorology-based icing intensity standard.
3. Fully characterize supercooled large droplet cli-
3. Determine the critical technical capabilities for a
matology.
remote-sensing system, such as range needed to
4. Characterize liquid-water content, drop size, and
observe through most icing conditions, scanning
temperature conditions in all icing synoptic situa-
rate/resolution, accuracy. Information needed is
tions.
primarily meteorological, but also operational.
5. Determine the variability of cloud characteristics
4. Weather forecasters and numerical models need
(such as liquid-water content, droplet size, and
downlinked objective, timely temperature, liquid-
temperature) within 3-D space (vertical and hori-
water content, and drop-size information that is
zontal).
accurate in position.
6. MVD or equivalent may not be acceptable
because they poorly represent "nonstandard" (i.e.,
STATE OF KNOWLEDGE
non-Gaussian) distributions of drop sizes
observed in clouds with drizzle drops.
Characterization
7. Drop-size distributions are often not correctly
1. 3-D organization of icing patches is poorly under-
represented by current instrumentation, and ice
stood with regard to usefulness of a remote-
crystals or drops can confuse sensing systems.
sensing system.
Better instrumentation is needed.
2. Range and scale of liquid-water content, drop size,
8. More research flights specifically planned to
and temperature variability is not well understood
measure information needed to characterize the
in 3-D space, especially at the submesoscale, and
icing environment with regard to remote-sensing
especially for supercooled large drops.
systems--with better instrumentation.
3. Climatology of supercooled large drops is poorly
9. Rework existing flight data.
understood.
10. Measure cloud microphysical properties and
4. Submesoscale, continental, and global scales of
resulting ice on aircraft with in-situ sensing sys-
aircraft icing are poorly understood.
tems to calibrate remote-sensing system dynam-
5. Drop-size distributions are not well characterized
ically.
by current instrumentation--especially for larger
11. Improve characterization of freezing rain aloft.
drops.
12. Characterize droplet temperature variations.
6. Ranges of liquid water content are reasonably well
13. Characterize mixed-phase clouds with tempera-
understood, but not in relation to drop size and
ture.
temperature.
7. Synoptic scale of icing is reasonably well under-
In-situ instrumentation
stood.
1. In-situ instruments with better dynamic range and
8. General climatologies of aircraft icing exist and
sensitivity.
are reasonably well understood.
2. Small, accurate, and inexpensive in-situ technol-
9. Research flight information exists that can be reanal-
ogies.
yzed at little cost for better characterization.
3. Improved SLD measurement instrumentation.
10. Characterization of freezing rain and freezing driz-
zle aloft poorly understood.
11. Characterization of temperature poorly understood.
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