# Presentation: 125603

##     The Variety of New Commercial Aircraft Sensors

**    ****for Weather, Climate, and Air Quality Applications:**
**	****                ****Accuracy and Use**

**                                 ****Dr. Rex J. Fleming**
**                               ****SpectraSensors, Inc.**
**                                   ****May 16, 2006**

## Time is right for a paradigm shift in observations for atmospheric science

** ****	****Observational accuracy has not kept pace with ****	****advances in computers and modeling/analysis ****	****capabilities**
** ****	****Platforms that ****move**** on our planet can **_**potentially**_** make ****	****enormous contributions with ****continuous measurements ****	****in space/time.**
** ****	****If measurements are **_**extremely accurate,**_** then valuable ****	****in their own right and make satellite data (conventional ****	****or GPS related) more valuable (via Kalman filter, 4DDA,             **
**      ****or other optimization methods)**

**Time is right for a paradigm shift in observations for atmospheric science**

## “Accurate” Environmental Data will Escalate in Value over Time 

-  **	****Weather and climate already impact about 1/7 of a 7 ****	****trillion dollar USA economy**
-  **	****Consider growth in 7 major socioeconomic areas:**
**  ****Energy: largest single issue for USA and the world**
**  ****Water: fresh water is 2****nd**** largest issue for society**** **
**  ****Food: average population increase only 1.1%/yr vs 1.7% past 30 yr**
**  ****Transportation: major growth area (aviation impact already huge****)**
**  ****Weather impacts: (human health, safety, etc) vs 1.1% pop. growth**
**  ****Climate change (global warming uncertainty vs energy conflict)**
**  ****Construction and other: Population growth 1.1%/year**
-  	**Value of ****“accurate”**** environmental data will double ****	****approximately every 6-8 years in future.**

## Commercial Aircraft create a paradigm shift in atmospheric

**observations – for the benefit of aviation and society**

**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; little information from cloud winds**
**Commercial aircraft****:**** space/ time coverage from moving platforms**
**provide unique data blend that helps merges all these data sets**
**into 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**
**The Next Generation Air Transportation System (NGATS) will depend**
**on the aircraft measurements (commercial & possibly general aviation)**

## This Presentation Covers Three types of Sensors (all same architecture)

**2****nd**** generation Water Vapor Sensing System (WVSS-II)**
**   ****-- WVSS-II (current for commercial jets) in USA and Europe**
**   ****-- WVSS-III for turboprop a/c and ****all mobile**** ****platforms ****below 25,000 ft**
**   ****-- ****Modified WVSS-II**** for upper troposphere and stratospheric **
**       ****research (Herriott cell inside; same size, but more expensive)**
**Mobile Temperature Sensor (MTS)**** for better temperature from a/c and**
**other mobile platforms**
**Quantum cascade (QC) lasers**** for atmospheric trace gases**

## Emergence of mobile platforms [commercial aircraft (jets and 

**turboprops), helicopters, unmanned  aerial vehicles (UAVs), etc.]**
**driven by:**
**Convenience – mesoscale coverage in USA, over ocean with satellite**
**                           ****communications, difficult/dangerous regions via UAVs**
**Sensor accuracy – dramatic turn for the better with new technology**
**Demand for more accurate data – socioeconomic demand is**
**                                                           ****accelerating  **

## Water vapor from mobile platforms

## History: WVSS-I

**Results and why RH by thin film rejected: ****www.joss.ucar.edu/wvss/**** **

## Why WVSS-I (RH sensor) Abandoned by FAA and NOAA/OGP

**4 years of  flight tests with UPS [Vaisala thin film sensor–best of radiosondes**
** – ****has following known problems in measuring relative humidity (RH)]**
**  ****-- difficult to calibrate at very low and high RH values**
**  ****-- calibration changes over time**
**  ****-- sensor response time is very slow at cold temperatures**
**  ****-- sensor reads well over 100% when wet; cosmetic fix;  takes time to dry**
**Mach effect on aircraft bad for RH measurement (****not for mixing ratio or dew pt.)**
**  ****-- amplifies sfc random error (5%) by factor: (3) for turboprops (17) for jets**
**Found large changes between aircraft to aircraft over time**
**  ****-- limitation of thin film – each manufactured lot is different, and within each lot**
**         ****each radiosonde has to be calibrated individually**
**  ****-- results show average lifetime 6 months (based upon loss of sensitivity**
**         ****at upper levels)**
**European Project MOSAIC (Measurement of Ozone by Airbus In-service Aircraft)**
**  ****-- 10 year effort of**** recording**** ozone and water vapor (using Vaisala thin film**
**         ****sensor) produced over 2500 over-ocean flights with 140,000 hours of data**
**  ****-- had to recalibrate the Vaisala sensor every month (Herman Smit, Germany) **

## Error analysis: Mach Number Effect

- z:/fleming/vgraphs/Error analysis.ppt

**If Mach #  =  0.8,   T****s****  =  -60C  =  213.15K**
**then:**
**	****T****probe**** = T****static**** (1 + 0.2M ****2****)  =  T****static**** (1.128)  =  240.43**
**	****P****probe**** = P****static**** (1 + 0.2M ****2****) ****3.5****  =  P****s**** ****(1.524)**
**and:**
**	****e****s, s ****(213.15)  =  1.76**
**	****e****s, p ****(240.43)  =  38.41**
**and from   RH****static****  =  RH****probe****  (e****s,probe**** / e****s,static**** ) (P****static ****/ P****probe**** )****   **
**RH****static**** / RH****probe**** = ****(e****s, probe****/e****s, static****)**** ****(P****static****/P****probe****)**
**	****	**** ****= ****(38.41/1.76****) / (****1.524****) = ****14.32**

## Slide 11

## Slide 12

## I = I0 exp ( - σ n L )

**I ****= intensity at detector**
** **
**I****0**** = initial intensity****	****	****	**
**σ**** ****n L = absorbance**
**          ****= ****α**** **

**WVSS-II Sensor Technology: absorption spectroscopy – transmission**
**          ****of ****laser light**** through absorbing gas ( diode laser @ 1.37 micron)**

**I = I****0**** exp ( - ****σ**** n L**** ****)**

**I****0**

**n = number density of gas**
**L = path length**
**σ**** = molecular absorbing cross**
**       ****section = ****σ**** ( ****μ**** P T )**
** **

**I**

## Photo: WVSS-II Air Sampler

## WVSS-II on UPS B-757

**Figure 2.  Cross section of complete sampler**

**Turbulence enhancer **

**Cylindrical sampling tube**

**Inertial separator (inside, see Fig. 3)**

**Aircraft skin**

**8.89 cm**

**24 cm**

## Installed System Photos

- WVSS-II Air Sampler

- Open Path Sensor

## NOAA P3 Flight Profile

## NOAA P3 Center Flight Section

- Chilled mirror overshoots

## WVSS-II on UPS B-757

**  ****Diode laser, 20 year life, telecommunications standard**
**  ****System weight (electronics box, cables, air sampler) < 7 lbs**
**  ****Overall Box Dimensions 5.0” x 9.0” x 3.1”**

## Key Events in Operational WVSS-II Product History

**FAA Certification for B-757 cargo aircraft                           12/04**
**UPS installation of 25 units                                        3/05 to 6/05**
**Early results (all on internet in real time)**
**  ****-- 3 of 4 errors proven fixed on subsequent installations**
**  ****-- 4****th**** error fix proven in lab (being certified)– heated hose**
**  ****-- all units retrofitted after certification **
**WVSS-II vs radiosonde in U. of Wisconsin tests                  6/05**
**  ****-- conducted by W. Feltz and R. Petersen**
**Six units shipped to Germany for A320  certification          3/06**
**Airbus visit to SpectraSensors for final evaluation             ****5/06**
**  ****-- European AMDAR requested Airbus consider the **
**     ****WVSS-II for all Airbus aircraft (considerable exchange)**
**  ****-- visit by Airbus staff for final check of manufacturing**
**     ****ability, quality control, and meeting schedules for deliveries**

## Simple Optical Layout of WVSS-II H2O Sensor

- Laser

- Detector

**Simple Optical Layout of WVSS-II H2O Sensor**
**                         ****(not to scale)**

- Mirror

- Thermal Block

- 12 cm each way

**24 cm optical absorption pathlength for measurements**

**Note that there is a 0.5 cm path within optical head**

## 1st Hardware change: Remove leak in optical head

**First 11 aircraft carried surface water vapor aloft**
**Problem identified and solution found:**
** ****-- profile comparison with radiosondes great, but some a/c always had 100%**
**     ****RH in upper trop. ****(most distressing**** because every decision has been driven**
**     ****to obtain accuracy in this very poorly measured portion of the atmosphere).**
** ****-- connector to back of optical head was ****not truly hermetic**** allowing vapor**
**     ****behind a 1.0 cm path (compared to true measurement over a 24 cm path).**
** ****-- ****natural gas water vapor sensors of SSI**** have better connector and ****4X**** **
**     ****more desiccant**** ****in optical head (field proven ****3+ years of lifetime****)**
** ****-- solution two fold: source found for ****true hermetic versions of same**** ****connector**
**     ****(****tests indicate desiccant would last 200 years****) and simple design changes**
**      ****in optical head allow ****6X more desiccant****.**

## 2nd hardware change required: heated hoses 

**Had debate three years ago about descent into very warm and humid**
** ****conditions – would condensation be an impact (system or data) ?**
**Impact issue was more about the system rather than the data**
** ****-- heated hose was considered rather more complicated and system**
**     ****would flush any water on next ascent taxi**
** ****-- ****now appears that the condensation does pull sufficient water vapor**
**     ****from the air sample to lower the mixing ratio (despite the fact that**
**     ****2500 Joules per gram of water are released as heat to help reduce the **
**     ****condensation).**
**Solution is same easy solution used by Randy May for NASA: **
**same company makes heated hoses with a controller.**
**Circuit keeps measurement cell at 35 C.**

## Slide 24

## Slide 25

## Slide 26

## Summary of European Activity Concerning WVSS-II

**The**** ****German Weather Service working with Lufthansa and Airbus will fund the certification of the A320 family of a/c (A319, A320, A321)**
**The first 10 WVSS-II units will go on new A320 aircraft to be delivered to Lufthansa (5), Air New Zealand (1) Jet Star –Australia (2), and South African Airlines (2)**
**Herman Smit (scientist with MOSAIC project has been testing the WVSS-II Electronics box in his lab – if they like, they will certify for A340 and put on 6-8 MOSAIC aircraft**
**The European AMDAR group has asked Airbus to consider the WVSS-II as an optional product for all of their aircraft (they have come to SpectraSensors with detailed questions and are still evaluating)**

**Summary of European Activity Concerning WVSS-II**

## Temperature from mobile platforms

## Commercial Aircraft measurements of atmospheric temperature

**8 years ago I first heard about problem – Qantas B-747 (3 sensors)**
**4 years ago I began thinking about the problem – subliminally**
**2 years ago I solved problem ,conceptually, and verified via**
**     ****complex simulations that it would work**
**6 months ago Randy May and I proved the concept at the U. of**
**     ****Washington wind tunnel **
**While I believe the solution is proven by wind tunnel results and **
**     ****simulations, ****you and others will believe it only after actual flight**
**     ****tests in the next 6-8 months – of course!**
**Today, you will hear some detail, not all; fully patent protected**

## Commercial Aircraft measurements of atmospheric temperature

**Commercial Aircraft measurements of atmospheric temperature**
**   ****TT = TS ( 1 + 0.2 M**** 2**** )                         Measurements are:**
**Indirect:  avionics measure TT not TS (which we want)**
**Affected by heated probe: outside a/c skin boundary layer, therefore**
**    ****FAA requires the Total Air Temperature (TAT) probe be heated**
**Intrusive: measurement affected by environment over time**
**--------------------------------------------------------------------------------------------**
**Solution:  Measure TS directly**
**Measure TS within boundary layer (no heater); isolate effect of friction**
**   ****and model that effect via singular value decomposition (SVD)**
**Imbed sensors (2) within walls (5/1000 of inch) protected from**
** ****environment**

## Four Requirements for a Successful Flush Mounted

**                            ****Temperature Sensor**

**Location on fuselage with reasonably laminar flow**
**Sensor housing thermally shielded with insulating gaskets**
**   ****(from external heat source (sun) and internal heat sources)**
**Friction effects (thus isolated with above shielding) produce**
** ****temperature increase modeled with a polynomial in Mach Number:**
**                   ****Δ****T****F**** = A****1**** + A****2**** M + A****3**** M****2**** + A****4**** M****3**
**Model parameters (A****K****)  determined from powerful Singular Value**
**  ****Decomposition and additional optimizing proprietary software****         **

## Slide 32

## Problems with TAT probes  (Our fixes)

**Accuracy ****(0.3 is expected error: 2 to 3 times better)**
**at best, 0.6 to 0.8****o accurate**
**large variability seen (random errors and biases)**
**changing calibration (birds, other factors)**
**Probe heater  ****(no heater required)**
**largest failure mode = delay time, repair costs**
**limits temperature accuracy**
**Probe drag    ****(far less drag)**
**additional fuel costs = approximately $3M per year for 8000 aircraft in USA**
**Probe’s radar cross section  ****(far less cross section)**

**Military already seeking flush mounted versions of TAT and pitot tube**

##                             TT = TS ( 1 + 0.2 M 2 )

**       ****TT = TAT    TS = SAT   TM = measured total temperature   TR = recovery temp**

**                            ****TT = TS ( 1 + 0.2 M ****2**** )**
**Extreme: long term effects of rain, snow, hail, icing can damage sensor**

**   ****Figure from Rosemount (BF Goodrich) Technical Report 5755, Rev B, 1990**

**Possible errors:**
**Probe heater**
**Correction factor**
**Slow time response**
**Self heating (I****2**** R )**
**Extreme**** environment**

## WVSSII Installation at 

**WVSSII Installation at **
**United Parcel Service Maintenance Facility**

**Photo Credit:** UPS Dispatch
**Contact for Usage:**  Randy Baker/UPS; Email:  air1rtb@ups.com

## UCAR Patented Mobile Temperature Sensor (MTS)

**Thermal shielding (insolating gaskets) above and below T sensor area**

## Slide 37

## Slide 38

## Slide 39

## Slide 40

## Slide 41

## Slide 42

## Slide 43

##         Atmospheric trace gases

**         ****from mobile platforms**

## Slide 45

## Diode lasers and quantum cascade (QC) lasers for various trace gases

**Air quality (regional and global pollution) and climate change**
**   ****QC lasers invented in 1994**
**   ****these are very small lasers (smaller than diode laser)**
**   ****key is operation at room temperature in continuous  wave (cw) mode**
**   ****prices are still coming down**

## Diode lasers or QC lasers for atmospheric trace gases

**Same architecture as WVSS-II**
**   ****-- ****same air sampler****; 1.37 ****μ****m replaced with longer wavelength laser**
**   ****-- single path or multiple path (Herriott cell) depending on species**
**   ****-- internal Systems Electronic Box (SEB) about same size**
**   ****-- higher price  than WVSS-II (function of  laser costs)**
**Initial products design for CO****2**** and O****3**** [****α**** = 1 x 10****-4  ****accuracy = 5%]**
-           ** ****Feature    **                          ** ozone (9.2 ****μ****m)****    Carbon dioxide (2.7 ****μ****m)**
**  ****minimum detectable signal          0.01 ppmv              0.1 to 0.5 ppmv**
**  ****maximum detectable signal            10 ppmv           1000 ppmv **
**  ****path length (in centimeters)                600                       24**
**  ****measured precision                 2% or 0.01 ppmv     1% or 0.1 to 0.5 ppmv**

## What is driving the need for more accuracy?

**   ****An evolving, complex, global society –**
**   ****where all inhabitants are striving to raise**
**   ****their standard of living**

## “Accurate” Atmospheric Monitoring Data 

-  	Consider growth in 7 major socioeconomic areas
-  **Energy: largest single issue for USA and world (see charts)**
** ****Water: second largest issue for society (see chart)**
** ****Food: not as serious as before (see chart)**
** ****Transportation: major growth area (see chart)**
-  Weather impacts (human health, safety, etc) vs 1.1% pop. growth
-  Climate change (global warming uncertainty vs energy conflict)
-  Construction: population growth 1% per year for several decades
-  	**Value of “accurate” environmental data will double ****	****approximately every 6-8 years in future.**

**“****Accurate” Atmospheric Monitoring Data **
**will escalate in value over time**

## Next Generation Air Transportation System (NGATS):  Projected demand

**Next Generation Air Transportation System (NGATS):  Projected demand**
**   ****120 million additional international passengers are expected by 2025**
**   ****one billion expected in US air space by 2015**
**   ****passenger demand will double or triple by 2025; cargo will triple**
**   ****speed and predictability of air transportation has businesses depending**
**   ****upon just in time air shipments for production efficiency and for keeping**
**   ****inventory costs low – improving our standard of living****)**
**   ****doing nothing will cost consumers $30 billion annually**
**Importance to United States**
**   ****civil aviation products and services generate a significant surplus for US**
**      ****trade accounts**
**   ****contribute to the $100 billion a year tourism from abroad**
**   ****air transportation has spawned a highly technical work force**
**   ****aviation technologies, products, and services underpin the advanced**
**   ****capabilities of our national defense and homeland security **

## The Next Generation Air Transportation System

**The affordability of fossil fuels**
**The emergence of new markets in Asia that drive air transportation development**
**The increased importance of timeliness (speed and predictability)**
**The continuing or increasing level of world tension**
**The health and environmental concerns pervading normal every day routine**
**  ****and the ****growing issue of aviation’s role in climate change**** **
**Variations in the above scenarios will drive major changes in the way air traffic **
**is managed, lead to more efficient and environmentally friendly vehicles, lead**
**to more ****point-to-point operations****, greater use of satellite and reliever airports,**
**and ****new types of aircraft**** in the National Airspace System:**
**5000 microjets employed by on-demand air taxi services by 2010; 13,500 by ’22**
**greater use of UAVs for many applications (e.g. forest fires, surveillance, etc)**

## Three areas demanding more accurate data

**Aviation industry****:  (water vapor and temperature)**
**      ****-- industry in trouble**** now**** (fuel costs have strong wx dependence)**
**      ****-- ****future ****problems with global climate change; “Aviation and the ...**
**Global climate change****: (water vapor, temperature, and trace gases)**
**     ****-- reducing uncertainties in ****timing**** and ****intensity**
**     ****-- more accurate temperatures in upper troposphere**
**     ****-- water vapor (loading and role in clouds and aerosols)**
**Global air quality****: ( 3-D pollution near cities & trace gas information)**
**     ****--  this application just beginning to resemble weather prediction**
**          ****in early days – need more3-D data from ****aircraft**** and satellite**

##                                       Concluding remarks

**You have heard some new technology coming from commercial aircraft**
**(and eventually used on  many other mobile platforms).**
**There are other technologies that have are also coming:**
**  ****Doppler lidar winds**
**  ****slant path water vapor metric from such aircraft**
**  ****a turbulence metric from commercial aircraft based upon GPS which**
**  ****contributes to a similar metric from ground sites  -- together making a**
**  ****national turbulence product available in real time (provisional patents **
**  ****for each component submitted by R. J. Fleming, Global Aerospace,LLC)**
**In all of these applications I would ask that you help push for the highest**
**possible accuracy – our scientific challenges demand no less.**