The Vaisala Reference Radiosonde Program: First Results and Future Plans

Transcription

1 The Vaisala Reference Radiosonde Program: First Results and Future Plans Presentation in the NMM 2010, Helsinki, Finland, 9 June2010 Heikki Turtiainen, Hans von Bagh, Hannu Jauhiainen, Terhi Lehtola, Johanna Lentonen, Petteri Survo, Veli-Pekka Viitanen Vaisala Oyj, Helsinki, Finland Walter F. Dabberdt Vaisala Inc, Boulder, Colorado

2 Presentation outline Vaisala Reference Radiosonde Program overview RR01 radiosonde prototype First sounding results Next steps Page 2 / Vaisala

3 Vaisala Reference Radiosonde Program Vaisala is committed to research on climate change by providing the best possible tools for the meteorological community. In January 2009 Vaisala launched a program to develop an operational reference-grade radiosonde for climate studies and other applications where enhanced radiosonde performance is required (especially the GRUAN network). The development will be done in close collaboration with the international scientific community. Page 3 / Vaisala

4 Vaisala Reference Radiosonde Program The program will concentrate first on upperair measurements of humidity, the most abundant and most important greenhouse gas in the earth's atmosphere. The first version of the operational reference radiosonde uses a new advanced capacitive DRYCAP humidity sensor. Page 4 / Vaisala

5 Reference Radiosonde Program Status report 2012 Program launch AMS 2009 Status report AMS 2010 Status report 2011 Phase B - DRYCAP sensor module further development Phase A - First prototype of the Reference Radiosonde: RR01 Phase C Phase D Phases C, D... Input needed from the scientific community to define the goals! appr. 5 years OPERATIONAL REFERENCE RADIOSONDE Page 5 / Vaisala

6 Extremely sensitive DRYCAP humidity sensor Advanced capacitive sensor based on Vaisala DRYCAP technology, originally developed for measuring ultra-dry gases in industrial applications. Primary measurand is water vapour pressure (Pw), which is then converted to frostpoint temperature. Highly sensitive sensor material enables humidity measurements in upper troposhere and lower stratosphere: measuring range from -30 to -90 C frostpoint temperature. Sensor is operated at constant temperature above the ambient, resulting in faster response time, improved accuracy (no need for temperature correction) and simple calibration process. On-flight autocalibration procedure removes drift. Calibrated against a chilled mirror with traceability down to -90 C Page 6 / Vaisala

7 First experiments with an early prototype of the DRYCAP humidity sensor RS92 radiosonde sensors DRYCAP humidity sensor Page 7 / Vaisala

8 Page 8 / Vaisala First test soundings in FMI Sodankylä Observatory, July 2007

9 height (m) Test sounding in Sodankylä, 17 July 2007 Drycap (APS) and CFH data expressed as frostpoint temperature CFH Drycap (APS) T ambient T ( C) Page 9 / Vaisala

10 Sodankylä flight tests: technical feasibility verified Consistent stratospheric humidity measurement down to -92 C frost point. Low noise Small deviation against the Cryogenic Frostpoint Hygrometer (CFH), within 1 K in most part of the sounding Page 10 / Vaisala

11 DRYCAP humidity sensor performance in the LUAMI Campaign, DWD Lindenberg Page 11 / Vaisala

12 Tfp ( C) LUAMI flight at 12 Nov 2008, 10: CFH Drycap (APS) T ambient Time (min) Page 12 / Vaisala

13 In the LUAMI campaign DRYCAP humidity sensor performed consistently, with a slight positive difference compared to CFH Encouraging results especially in the stratosphere, where the sensor gave monotonically decreasing frost point temperatures with small variance. No temperature dependence observed. Four of the 13 soundings, made during rain of fog, showed large deviations. Suspected reason is "moisture contamination" (wetting or condensation, and consequent formation of ice on the sensor shield or nearby surfaces in the lower atmosphere). In the stratosphere, the accumulated ice begins to evaporate, causing observation error. Compared to CFH, DRYCAP humidity sensor showed on the average appr. 2 C higher frostpoint temperatures. Page 13 / Vaisala

14 Program progress RR01 production prototype designed DRYCAP sensor module (RRD100) electronics updated Calculation algorithms refined Sonde mechanics designed Production calibration process developed Post-processing software designed Systematic field testing and evaluation started (first RR01 vs CFH comparisons done in Sodankylä December 2009) RS92 and RR01 metadata pages datacontinuity.html ons/referenceradiosondeprogram.html Page 14 / Vaisala

15 RR01: the first version of the Reference Radiosonde Goal: easy to use, reasonable cost reference grade sonde to enable frequent, operational climatological soundings. DRYCAP humidity sensor for upper tropospheric and stratospheric humidity measurements RS92 sensors for pressure, temperature and tropospheric humidity RS92 GPS wind finding Ground equipment: Vaisala DigiCora + post-processing PC software package Availability: prototypes for evaluation to research partners during 2010 Page 15 / Vaisala

16 Tfp ( C) RR01 vs CFH sounding test, Sodankylä 12 Dec 2009 (daylight sounding)- expressed as frostpoint temperatures RR01 CFH T ambient time (min) Page 16 / Vaisala

17 Testing continued in the LAPBIAT2 campaign, Sodankylä January March Results to be presented in the TECO 2010 conference Page 19 / Vaisala

18 Next steps: testing and development continues to optimize the design and enhance performance Field testing continues with the research partners (FMI, NCAR). Optimization of the mechanical design (especially the sensor shield) to remove the observed moisture contamination effect and achieve allweather capability. Trimming of the on-flight autocalibration algorithms. Participation in the WMO Radiosonde Intercomparison in Yangjiang, China (July 2010), Scientific Sounding Instrument (SSI) group. Development of higher volume production capability. Page 20 / Vaisala

19 Summary The Vaisala reference radiosonde (RR01) has entered the prototype phase. RR01 is based on Vaisala RS92 radiosonde sensors and DRYCAP sensor technology, capable of measuring extremely low humidity levels. The first sounding tests show that measurement accuracy and repeatability are at a high level when verified against the cryogenic frostpoint hygrometer (CFH). Compared to current reference grade instruments RR01 will be considerably easier to operate and less expensive, thus enabling more frequent climatological soundings. Vaisala, together with its research partners is continuing the development of RR01, aiming to make it widely available during Page 21 / Vaisala

20 More info: /referenceradiosondeprogram.html Thank You! Page 22 / Vaisala