iMet Rawinsonde/Anasphere Liquid Water Sonde PIs: David J. Serke (1), Andrew Reehorst (2) and Michael King (2) (1) NCAR/RAL, 3050 Mitchell Lane, Boulder, CO, 80301, 303-497-8311, serke@ucar.edu (2) NASA Glenn Icing Branch, Cleveland, OH, 216-433-3938, Andrew.L.Reehorst@nasa.gov, Michael.C.King@nasa.gov 1.0 Data Set Overview Abstract: An improved version of the vibrating wire sensor, used to measure supercooled cloud liquid water content, was developed by Anasphere Inc. and tested during early 2012. The sensor works on the principle that supercooled liquid will freeze to the vibrating wire and reduce the frequency at a known rate proportional to the liquid water content as the sensor rises through the cloud attached to a weather balloon and radiosonde. The disposable Anasphere sensor interfaces with an InterMet Systems iMet radiosonde. This updated sensor reduces the weight of the instrument while updating the technology when compared to the preceding balloon-borne sensor that was developed in the 1980?s by Hill and Woffinden. The data gathered from this sensor are potentially important to detection of icing hazards to aircraft, validation of microphysical output from numerical models, and calibrating remote sensors measuring supercooled liquid water. Data time period: Four separate launches occurred on 1/9/2014 between 7 and 15 UTC Physical location: All launches occurred from the roof of the meteorology building on the campus of SUNY Oswego (LAT 43.455, LON -76.539) 2.0 Instrument Description Please see one of the following links for relevant information: http://www.sciencedirect.com/science/article/pii/S016980951400235X https://ams.confex.com/ams/21Applied17SMOI/webprogram/Paper247186.html 3.0 Data Collection and Processing The SLW sondes are attached to a standard iMET radiosonde and communicate the time and wire frequency through to the radiosonde transmitter as an additional data packet. The radiosonde data are recieved by a ground receiving station and collected by the NOAA 'SkySonde' Client. Data processing to arrive at SLW Content is described in detail in the 'Atmospheric Research' paper referenced above. 4.0 Data Format File naming convention: Files are named as {fc}{fl#}_{yyyy}{mm}{dd}.{fmt} where: fc = field campaign (ex: 'ow' for OWLeS) fl# = sonde flight number yyyy = year mm = month dd = day fmt = format example: ow001_20140109.csv Sample file header information: NOAA/GMD balloon flight data file SkySonde Client Version: 1.1.1.1 Balloon Flight Name: ow001 Attached Instruments: Radiosonde Station Name: SUN Station Latitude: 43.46 Station Longitude: -76.54 Station Altitude: 100.00 [m] Station Pressure: 1017.00 [mb] Station Temperature: -7.000 [deg C] Station Humidity: 60.000 [% RH] Radiosonde Serial Number / ID: 17327 Pressure/Altitude Source: iMet Radiosonde Solar Radiation Correction: Yes Each file has the following data fields in separate columns or comma separated: date [d-m-y GMT] time [h:m:s GMT] milliseconds seconds since midnight [GMT] elapsed minutes altitude (from iMet PTU) [km] iMet pressure [mb] iMet air temperature (corrected) [deg C] iMet air temperature (raw) [deg C] iMet humidity [RH %] iMet frostpoint [deg C] iMet internal temperature [deg C] iMet battery voltage [V] iMet theta [K] iMet temperature (of pressure sensor) [deg C] iMet temperature (of humidity sensor) [deg C] iMet ascent rate [m/s] iMet water vapor mixing ratio [ppmv] iMet total column water (gas phase) [mm] iMet total column water (liquid phase) [mm] GPS latitude GPS longitude GPS altitude [km] GPS num satellites GPS pressure [mb] GPS wind speed [m/s] GPS wind direction [deg] GPS ascent rate [m/s] GPS(X) east velocity [m/s] GPS(X) north velocity [m/s] GPS(X) up velocity [m/s] GPS time [h:m:s GMT] GPS heading from launch [deg] GPS elevation angle from launch [deg] GPS distance from launch [km] predicted landing latitude predicted landing longitude predicted time to landing [min] Anasphere SLW Frequency [Hz] Anasphere Supercooled Water Content [g/m^3] 5.0 Data Remarks * NOTE: The actual calculation of SLW is accomplished by taking the second to last data field (SLW Frequency' and running the calculation described in Equation 1 of the Serke et al. Atmospheric Research paper. The last data field named 'Anasphere Supercooled Water Content' is an earlier, preliminary value calculated on the fly within the SkySonde software and should not be considered the final product. Data quality: There are several isolated short periods or even just single data points where the frequency data is roughly 2 times the starting, uniced frequency (base frequency is ~ 44 Hz). These should be considered bad data and be filtered out. Anasphere says these points are a result of some internal resonance being reported through from the frequency pickup and is being addressed in upcoming sonde versions. They stress that in no way does this reporting issue affect the quality of surrounding data points and simply results in the unfortunate loss of these few points. Reading in data file: Try stripping out the header files and use some function like csvread or similar in Matlab. Contact Dave and he will provide some homemade Matlab code for ingesting and plotting these data! :) 6.0 References Serke, D., E. Hall, J. Bognar, A. Jodan, S. Abdo, K. Baker, T. Seitel, M. Nelson, R. Ware, F. McDonough, and M. Politovich, 2014: Supercooled liquid water content profiling case studies with a new vibrating wire sonde compared to a ground-based microwave radiometer. Atmospheric Research, doi: 10.1016/j.atmosres.2014.05.026. http://www.sciencedirect.com/science/article/pii/S016980951400235X Serke, D. J., M. C. King, R. Hansen, B. Geerts, S. M. Steiger, and J. Bognar, 2014: A New Supercooled Liquid Water Content Sonde Compared to Research Flight Data, presented at 17th Symposium on Meteorological Observation and Instrumentation, Denver, CO. https://ams.confex.com/ams/21Applied17SMOI/webprogram/Paper247186.html