Facts on Water, Water Vapor, How to Measure Vapor on Commercial Aircraft, and It’s Impact On the Next Generation ATM System Dr. Rex J Fleming Global Aerospace,

Facts on Water, Water Vapor, How to Measure

Vapor on Commercial Aircraft, and It’s Impact

On the Next Generation ATM System

Dr. Rex J Fleming

Global Aerospace, LLC

January, 2009

Z:/fleming/vgraphs/Data Link.ppt

Atmospheric Water Vapor

• Enormous amount--on average, more water flows over dry state of Arizona than flows down Mississippi River

• Energetically important--volatile fuel

• Highly variable in space and time

• Currently poorly measured

• Important to aviation weather, storm prediction, atmospheric chemistry, global change

The Water Planet--But Fresh Water a Premium

Only 2.8% of water is fresh

Three-quarters of fresh water locked in ice caps and glaciers

No living thing can do without it!

200 gallons for loaf of bread

700 gallons for barrel of oil

2,600 gallons for one pound of beef

Today, 19 countries listed as “water scarce”

(<1,000 m3 (264,200 gal) available per person)

In next 30 years, 46 - 52 countries “water scarce” and 1 out of 3 people in this category

Other Interesting Facts about Water

60% of the human body is H2O

Water is nature’s chief solvent

One-half known elements in water; nutrients

Rise in plants of water solution of mineral salts, nitrates, phosphates, etc. (sap) is primarily driven by (i) evaporation from leaves (transpiration from above and (ii) capillary forces from below

• Giant redwoods pass a ton of water per day (for up to 2,000 years)

Energy Required for Changes “Upward”

(i) Ice Liquid 333 J/g-1

(ii) Liquid Vapor 2500 J/g-1*

(iii) Ice Vapor 2833 J/g-1

*Lw = Lo – L1T = 2500 at 0°C

= 2500 – L1T = 2257 at 100° C

Energy Calculations E = CPT + gz + Lq + K

CPT = (1 J g-1K-1)(293 K) = 293 J g-1

gz = (9.8 ms-2)(1000 m) = 10 J g-1

Lq = (2,500 J g-1)(2.0 x 10-2) = 50 J g-1

K = ½ V2(J/kg): (with V = 45 m/s) = 1 J g-1

CPT = (1 J g-1K-1)(205) = 205 J g-1

gz = (9.8 ms-2)(10 km) = 98 J g-1

Lq = (2,500 J g-1)(.2 x 10-2) = 5 J g-1

K = ½ V2(J/kg): (with V = 90 m/s, Jet core) = 4 J g-1

At 1 km

At 10km (~ 33,000 ft)

Note that change of water vapor to liquid releases 50 J g-1

Tornado impact in suburb of Oklahoma City(note wooden planks driven through side of car)

StabilityWarm air lighter than coldWet air lighter than dry

Mid level cold, dry air

Upper level jet

Low levelwarm, moistinflow

DFW

This situation caused $100M hail damage to American Airline fleet in Dallas Ft Worth airport in 1990’s.

Phenomena (Impacting Summary of Water Vapor on

Atmospheric Aviation in Terminal Area and En Route)

• Ceiling and Visibility (C&V)• Convection

– Microbursts– Thunderstorms– Severe thunderstorms with

hail

• Precipitation (type and amount)• Snow/Ice Storm (timing and

intensity• En route winds (mesoscale

impact)

• Air saturation• Stability of

atmosphere• Amount of water

available

• Amount of water available

• Water vapor fuels mesoscale convective systems

 Water Vapor Loading is a Key Issue for Global Warming

Radiosonde record suggests a very slight increase of IWV (can not trust radiosondes)

 Satellite record (NVAP predominantly satellite data) suggests

a very slight decrease (Record is short and uncertainties exist)

If IWV does not increase, then some indications suggest that doubling of carbon dioxide will lead to only 1/3 suggested

impact (0.5 to 1.5C vs 1.5 to 4.5) 

C o n c e p t u a l A t m o s p h e r i c O b s e r v i n g S y s t e m

L a n d

z : / f l e m i n g / v g r a p h s / C o n c e p t u a l O b s S y s . p p t

S e a

G r o u n d B a s e d r e m o t e s e n s i n g

S u r f a c e S t a t i o n s a n d / o r A i r p o r t

A i r c r a f t A s c e n t / D e s c e n t

G P S T o t a l C o l u m n W a t e r

A i r c r a f t E n r o u t e ( F l i g h t L e v e l )

R a d i o s o n d e s ( N e w a n d I m p r o v e d )

Commercial Aircraft create a paradigm shift in atmosphericobservations – for the benefit of society and aviation

Radiosondes: balloon launchs (2/day) have high vertical resolution; poor space and time resolution (500km, 1/day in many countries);do not serve high space /time requirements of aviation needs

Satellites: global cloud images very useful, but profile data inaccurate; poor vertical resolution on T and q; almost no information on winds

Commercial aircraft: space/ time coverage from moving platformsprovide unique data blend that helps merges all these above data setsinto a unifying whole; winds and water vapor more accurate

15 countries have organized national commercial aircraft programs; 18 more countries have programs in various stages of implementation

Next Generation Air Transportation System (NextGen) will dependon the aircraft measurements (commercial & possibly general aviation)

Z:/fleming/vgraphs/Data Link.ppt

Weather Analysis, Prediction, Analysis Cycle

• Global weather prediction

(usually 12-hour cycle)

• Regional weather prediction

(sometimes 6-hour cycle)

• In USA area due to weather data

via ACARS– Three-hour cycle (June 1992)

– One-hour cycle (June 1998)

– still missing water vapor!

First NOAA/NCAR effort (WVSS-I) measured relative humidity usingradiosonde technology– air sampler too big, data not accurate enough!

(a) (b)

(c)

50000 55000 60000 65000 70000600

650

700

750

800

850

900

950

1000

1050

NOAA P3 072104

Static Pressure

Pre

ssu

re (

mb

ar)

UTC (Seconds)

Flight profile

64000 64500 65000 65500 66000 66500 67000

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

NOAA P3 072104

CM #1 CM #2 open path wvss-ii

H2O

(p

pm

v)

UTC (seconds)

Center flight section

Chilled mirror overshoots

Three consecutive aircraft launched 9 minutes apart with radiosondeThree consecutive aircraft launched 9 minutes apart vs radiosonde

The WVSS-II on UPS B-757

Third party test at Louisville KY (UPS Main Hub)

Overview Success in several NextGen operational concept tests has led to accelerating the pace – referred to as NowGen

Better a/c measurements and products are required for both: -- to help improve the required navigation performance -- to improve performance in new ATM operations

Michael Lewis (Director of Business Development for Boeing Advanced ATM) has this quote concerning NextGen:“required innovation already exists as a technology, weather prediction is currently not as good as it needs to be”

Show impact of improved a/c sensors on two NextGen ops

Reveal new method for identifying turbulence for aviation

Motivation for weather improvements

Giovanni Bisignani (CEO of IATA) claims: “ shaving one minute off each commercial flight would save 5.0 tonnes of CO2 emissions and $3.8 billion in fuel costs each year ”

Carbon taxes may begin in January 2010!

Weather product improvements have made substantialimpact in fuel costs in past

Further progress essential for NextGen! Will show specific examples of how a/c sensors help in NextGen operations of: -- “flow corridors” -- “choreographed ascent / descent”

Forecast wind errors as a function of pressure (from NOAA/FSL)

Model wind errors from a regional forecast model

Flow Corridors: long tubes or “bundles of near parallel 4DT assignments which achieve a very high traffic throughput

Corridors planned in advance; adjusted every 2 hours withaccurate wx forecasts for efficiency – use of jet stream winds,avoiding turbulence, convection [temp (T) & water vapor [q])

Results (update rate=20 sec, 3 m/s wind error): RNP = 0.49 nm(eliminating TAT T bias, 1.5 m/s wind error): RNP = 0.26 nm

Sudden corridor change [rapidly growth in enroute convectionor moderate to severe turbulence, loss of key terminal] could lead to massive delays, safety issues, etc.

Unlike havoc on highway where autos can come to a stop -- high density a/c traffic needs to be shuffled somewhere!

Choreographed Arrival/Departure (future plans)

Results (update rate=16 sec, 3 m/s wind error): RNP = 0.31 nm eliminating TAT T bias, 1.5 m/s wind error): RNP = 0.16 nm

Continuous descent approach (CDA) can occur in all weather conditions, with mixed fleets, and even at busy terminals!

However, need accurate wind, temp (T), and water vapor (q) from commercial aircraft in the greater (150 nm) terminal area for analysis and projection of convection: turbulence,thunderstorms, microbursts, and wake vortices

Airport terminals will have 4-D picture of terminal area (out to~ 150 nm radius) from forecast model with 5 min refresh rate

Forecast errors of RH as a function of pressure (from NOAA/FSL)

How does one predict convection and support aviation with this skill?

Time for action on two major activities

Accelerate accurate a/c measurements of winds, T, and q

Implement passive turbulence system; GPS receivers abound,but must be modified; need corporate partner to help initiate

Immediate benefit of less fuel use and less carbon emissionsEvolving benefits for NowGen and NextGen operationsReduce potential passenger’s personal anxiety about flying

These basic infrastructure improvements serve all of society(beyond aviation) and will help stimulate all economies (in the USA weather and climate impact 1/7 of GDP)

Carbon taxes could help fund all the above requirements