-") 43rd Aerospace Sciences Meeting and Exhibit Conference AIAA-200S-02S9 10-14 January 2005, Reno, Nevada TAMDAR Sensor Validation in 2003 AIRS II Taumi. S. Dani els' and John J. Murrai NASA Langley Research Center, Hampton, Virginia, 23681 Mark V. A nd erso n ~ , D a ni e l J. Mulall y§, Kri topher R. Jensen" AirDat, LLC. , Evergreen, Co lorado, 80439 Cedric A. Graingertt and David J. Delene** University of No rth Dakota, Grand Forks, North Dakota, 58202 This study entails an assessment of T AMDAR in situ temperature, relative humidity and winds sensor data from seven flights of the UND Citation II. These data are undergoing rigorous assessment to determine their viability to significantly augment domestic Meteorological Data Communications Reporting System (MDCRS) and the international Aircraft Meteorological Data Reporting (AMDAR) system observational databases to improve the performance of regional and global numerical weather prediction models. NASA Langley Research Center participated in the Second AUiance Icing Research Study from November 17 to December 17, 2003. TAMDAR data taken during this period is compared with validation data from the UND Citation. The data indicate acceptable performance of the T AMDAR sensor when compared to measurements from the UND Citation research instruments. I. INTRODUCTION HE Tropospheric Airborne Meteorological Data Reporting (TAMDAR) sensor is designed to mea ure winds, T temperature, humidity, turbul ence and icing from regional commercial aircraft'. AirDat, LLC, developed th e 2 sensor under contract for NASA . A system of TAMDAR sensors and data lin ks on a suffi cient number of aircraft woul d provide hi gh temporal- and spati al-resolution wind and temperature data in the lower troposphere. Such a system has the potenti al to substantiall y improve weather fo recasting. Moreover, the hi gh-resolution hu midi ty data produced by T AMDAR is unprecedented, and may provide substantial benefits. The meteorological community i keenly in terested in additional observati ons of the lower troposphere and in parti cul ar moisture data as 3 evidenced by the Ameri can Meteorological Society Statement . The University of North Dakota (UND) Cessna Citati on II and the NASA ER-2 parti cipated fro m November 19 to December 14, 2003, a period of overl ap between two separate fie ld campaigns, the Second Alli ance Icing Research Study (AIRS II). AIRS II fli ghts were over Ottawa, Ontario and th e Mirabel Airport outs ide M ontreal, Quebec. To support the campaign, it was necessary to identi fy suitable cases for targeting, prov ide information on the location of sensitive areas, and have th e fac ilitie to control each observing system at short noti ce. Early morning 4 meteorological reports were used fo r daily aircraft routing. Additional informati on can be fo und on th e websites ,5. As part of the development process, the T AMDAR sensor has been tested in various ground-based facili ties and 6 on different atmospheric research aircraft . The subj ect of thi s report is va lidation of T AMDAR sensor usin g data other instruments install ed on the UND Citati on. Additional va lid ati on data came fro m GPS dropsondes (fTo m the UND Citation). In additi on, other data from two sounding instruments is used for compari son purposes . • Project Manager, Electromagnetics and Sensors Branch, NASA, MS-473, Hampton, VA 23681 t Atmospheric Scientist, Chemistry and Dynamic Branch, NAS A, MS-401B , Hampton, VA 2368 1 *Pres ident, AirDat LLC, 30746-410 Bryant Dr., Evergreen, CO, 80439 § Vice President, Ai rDat LLC, 30746-410 Bryant Dr. , Evergreen, CO, 80439 •• E ngineer, AirDat LLC, 30746-410 Bryant Dr., Evergreen, CO, 80439 tt Professor, Departme nt of Atmospheri c Sciences, UND, Grand Forks, ND, 58202 *~ Assistant Professor, Department of Atm ospheri c Sciences, UND, Grand Forks, ND, 58202 Ameri can In titute of Aeronautics and Astronautics II. ALLIANCE ICING RESEARCH STUDY II AIRS II objectives were to: a) develop techniques to remotely detect, di agnose and forecast hazard ous win te r conditions at airport , b) improve weather forecasts of aircraft icing conditions, c) improve characteri zation of the 7 aircraft icin g environment and d) improve our understanding of th e icing process and its effect on aircraft ,g In order to support th e AIRS II operati onal obj ecti ves, data was coll ected to: a) in vesti gate the conditi ons associated with supercooled large drop formation, b) determine conditions governing cl oud glaciati on, c) document the spatial di stribution of ice crystal s and supercooled water and th e conditions under which they co-exist, and d) veri fy the response of remote sensors to various cl oud particles, and determine how thi s can be ex pl oited to re motely determine cl oud compositi on. III. AIRCRAFT INSTRUMENTATION For th e AIRS II fli ghts, th e three main aircraft, the NRC Convair 580, the NASA Twin Otter, and the NCAR C 130 were j oined by the UND Citati on. Icing fli ght confi gurati ons typi call y consisted of the three main aircraft in fli ght pattern s near the Mirabel site. Data from the three main aircraft are not pre ented here and are onl y menti oned fo r completeness. However, data from T AMDAR sensor and th e UND Citati on instruments is pre ented. The UND Citati on aircraft is instrumented for in-situ cl oud phys ics research. For thi s fi eld campaign the T AMDAR sensor pac kage was installed on th e fu selage near th e ship 's pitot probe. In addition, th e aircraft was equipped to deploy NCAR GPS dropsondes. The NASA ER-2 carried the NAST-I instrument. The temperature sounding data were retrieved fro m NAST-I 9 in frared hyperspectral radi ances . NAST-I data were searched for th e locati on where and time when the ER-2 and th e Citation were coll ocated within a delta Latitude <= 0.05°, delta Longitude <=0.05°, and delta time <= 5 min. Mean values for temperature of NAST-I retri evals within the matching cri teri a are computed and reported as NAST­ I temperature data. The temperature accuracy fo r the T AMDAR sensor is ± I 0c. To veri fy this value, a comparison to UND Citati on Rosemount Model 102 Probe sensor data over th e peri od of interest and al so over the entire day's fli ght is made. The Rosemount sen or accuracy is 0.5°C. Both TAMDAR and Rosemount data are corrected for dynami c heating. The T AMDAR sensor has two independent RH sensors, Honeywell HIH seri es thin film capacitive types. As both were reporting very similar values, onl y data from one is used for thi s compari so n. The reported RH accuracy is +/- 5% for temperatures down to O°C and below airspeed of Mach 0.4. Above Mach 0.4 th e RH accuracy i +/­ ] 0%. A lack of calibrati on data below O°C fo rces an extrapolati on of the ava il abl e calibration data. While thi s is probabl y valid down to about -40°C, significant measurement differences will be apparent at the lower temperature extremes. With actual calibrati on data at the lower temperatures, the TAMDAR sensor values for relati ve humidity would be in line with the +/- 5% accuracy. To verify the T AMDAR RH values, a compari on to UND Citati on relati ve humidity data is made. There were two sources of relati ve humidity data on the UND Citati on, a tunabl e di ode laser instrument and an EG&G dew point hygrometer. Unfo rtunately, post campaign data analys is revealed th at both these instruments were mi scalibrated. Anoth er source of verifi cati on is GPS drop onde data. The initial dropsonde values fo r relative humidity are often reported about 60-75 seconds after launch. The values used in thi s paper were converted to Figure 1. November 24, 2003 Flight Track. relati ve humidity with respect to ice using the Hyland lO and Wexler formulation . The T AMDAR sensor computes wind peed and directi on from measured airspeed, aircraft (UND Citati on) magneti c heading, and GPS ground track. TAMDAR wind vector magnitude accuracy is +/-3.08 mls (+/- 6 kn ots). To veri fy thi s value, a comparison to UND Citation nose probe sensor winds is made. IV. CASE STUDIES For each case study, a description of the fli ght confi gurati on is fo llowed by comparison data. T AMDAR data is validated against the UND Citati on data and compared to sounding data from dropsondes (if avail abl e). 2 Ameri can Institute of Aeronauti cs and Astronauti cs A. November 24, 2003 Case Study On this date, the UND Citation flew an icing mi ss ion as shown in Fig. 1. A cold fron t was approaching the Mirabel area from the we t that was expected to produce signifi cant icing during the evening and early morning hours of the fol lowing day. The Citation was to position in Ottawa with th e expectati on of flying an early morning mission during the icing event on Tuesday, November 25. The Citation fl ew past Ottawa to penetrate the frontal zone and to measure the cloud mi crophysics before the sy tern reached Ottawa. The aircraft took off from Bangor, ME at 1808 UTC and flew through the frontal zone to Lond on, Ontario. Cloud microphysic data were collected at several temperature levels in the fro ntal system.