Last Update : 21 April 2017
H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers
|Coordinateur||Philippe Ricaud (CNRM, CNRS UMR 3589)|
|Correspondant CNRM||Philippe Ricaud|
|Site Internet du projet||HAMSTRAD|
The aim of the HAMSTRAD (H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) project is to measure the trends in water vapour and temperature profiles from the lower part of the troposphere to the lower part of the stratosphere and their links with climate change. The HAMSTRAD radiometer is a genuine state-of-the-art microwave instrument dedicated for the detection of 1) the 60-GHz oxygen line to measure tropospheric temperature profile, and 2) the 183-GHz water vapour line to get tropospheric H2O. In January 2009, HAMSTRAD did work for 12 days outdoors at Dome C but was powered down by the end of the campaign since the shelter was not completely finished. The radiometer has been definitively deployed inside a dedicated shelter in January 2010 and is working since then. Unfortunately, in June 2011, the noise diode associated to the 183-GHz receiver (H2O channels), enabling the internal calibration, failed that also affected the 60-GHz receiver (temperature channels). Thus H2O and temperature measurements were not available since that date. In January 2012, the noise diode has been changed. The instrument has been working nominally since February 2012. Liquid Nitrogen calibration is performed one or twice per year (summer/winter periods). The instrument is fully automated and data are sent to France on a daily basis.
The instrument measures absolute humidity and temperature from the surface to about 10 km altitude, together with integrated water vapour (IWV), with a time resolution of about 7 minutes. Data recorded from 2009 to 2014 have been intensively analyzed and scientific results have been published. A new parameter (LWP = Liquid Water Path) is retrieved since 2013, and should be sensitive to the presence of clouds above the station. This parameter will need to be validated against measurements from other instruments at the station. A detailed presentation of the HAMSTRAD radiometer together with all the validation and scientific studies performed with the HAMSTRAD measurements are listed in the section 5, References.
By considering the HAMSTRAD measurements performed from 2009 to 2014 and other data sets e.g. in situ, radiosondes, satellite, lidar, meteorological analyses, backtrajectories, mesoscale models, we have already studied i) the strengths and weaknesses of this instrument by calculating biases and correlations, and ii) the different processes occurring in the Antarctic troposphere : 1) diurnal variability of temperature and H2O in the planetary boundary layer, 2) seasonal variability of temperature and H2O in the planetary boundary layer and in the free troposphere linked to the origin of air masses (dry and cold periods associated with Antarctic origin of air masses whilst less dry and less cold periods associated with oceanic origin of air masses), 3) temperature vs. H2O correlation along the vertical from the lowermost to the middle troposphere, 4) episodes of clouds and diamond dusts above the station.
Based upon previous studies, we can infer three recommendations regarding the use of HAMSTRAD data. 1) HAMSTRAD IWV measurements from 2009 to 2014 are of excellent quality (r > 0.98) and can be used without retrieving any bias. These 7-minute time resolution data are suitable for scientific analysis considering both an absolute comparison (in unit kg m-2) and a relative time evolution of this parameter (e.g. a temporal anomaly). 2) HAMSTRAD temperature measurements are suitable for scientific analyses over the range 0-10 km with a high correlation (r > 0.80) with radiosondes. The time evolution of this parameter over the period 2009-2014 with a 7-min resolution is meaningful. Nevertheless, the vertical distribution of temperature from 0 to 10 km is subject to biases that need to be removed if the scientific analyses require the use of vertical profiling. 3) HAMSTRAD absolute humidity measurements are suitable for scientific analyses over the range 0-4 km. Above 4 km, both the amount of H2O dramatically decreases and the instrument loses sensitivity. The time evolution of this parameter over the period 2009-2014 and over the range 0-4 km with a 7-min resolution is meaningful (r > 0.70). Nevertheless, the vertical distribution of absolute humidity from 0 to 4 km is subject to biases that need to be removed if the scientific analyses require the use of vertical profiling.
In the Table 1, we list all the measurements performed by HAMSTRAD on a yearly basis since 2011. They are all available in ASCII and binary IDL SAV formats except the biases in ASCII only. For one considered year, accessible are : temperature (K), absolute humidity (H2O, g m-3), IWV (kg m-2) and LWP (g m-2) [only in 2013-2016] on a 7-minute integration time, in seconds from 1st of January. Yearly-average temperature and absolute humidity bias profiles are given in K and g m-3, respectively (not yet available for the year 2016). Heights are in km above surface. The retrieval vertical grid is set to 39 levels, namely at 0, 10, 30, 50, 75, 100, 125, 150, 200, 250, 325, 400, 475, 550, 625, 700, 800, 900, 1000, 1150, 1300, 1450, 1600, 1800, 2000, 2200, 2500, 2800, 3100, 3500, 3900, 4400, 5000, 5600, 6200, 7000, 8000, 9000, and 10000 m.
Table 1. List of the files containing the HAMSTRAD measurements performed at Dome C for the years 2009-2016
The access to the HAMSTRAD data set is open to the scientific community. Please consider sending an email to the Principal Investigator, Philippe Ricaud (firstname.lastname@example.org) to let him know the purpose of your study. When publishing results containing HAMSTRAD data, you can include his name in the author list and/or add the following acknowledgment sentence :
The HAMSTRAD programme (910) has been funded by the Institut National des Sciences de l’Univers (INSU)/Centre National de la Recherche Scientifique (CNRS), the Institut polaire français Paul-Emile Victor (IPEV), Météo-France and the Centre National d’Etudes Spatiales (CNES).
Ricaud, P., Bazile, E., del Guasta, M., Lanconelli, C., Grigioni, P., and Mahjoub, A. : Genesis of diamond dust, ice fog and thick cloud episodes observed and modelled above Dome C, Antarctica, Atmos. Chem. Phys., 17, 5221-5237, doi:10.5194/acp-17-5221-2017, 2017.
Angot, H., Magand, O., Helmig, D., Ricaud, P., Quennehen, B., Gallée, H., Del Guasta, M., Sprovieri, F., Pirrone, N., Savarino, J., and Dommergue, A. : New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale, Atmos. Chem. Phys., 16, 8249-8264, doi:10.5194/acp-16-8249-2016, 2016.
Ricaud, P., P. Grigioni, R. Zbinden, J.-L. Attié, L. Genoni, A. Galeandro, L. Moggio, S. Montaguti, I. Petenko and P. Legovini : Review of Tropospheric Temperature, Absolute Humidity and Integrated Water Vapour from the HAMSTRAD Radiometer installed at Dome C (Antarctica) over the period 2009-2014, Antarctic Science, 27, 598-616, 2015. doi:10.1017/S0954102015000334, 2015.
Ricaud, P., Carminati, F., Courcoux, Y., Pellegrini, A., Attié, J.-L., El Amraoui, L., Abida, R., Genthon, C., August, T. and Warner, J. : Statistical Analyses and Correlation between Tropospheric Temperature and Humidity at Dome C, Antarctica, Antarctic Science, 26, 290 – 308. doi:10.1017/S0954102013000564, 2014.
Ricaud, P. : Variabilités de la vapeur d’eau et de la température troposphérique au Dôme C (station Concordia), Antarctique. Partie I : l’instrument Hamstrad, La Météorologie, 84, 15-28, doi:10.4267/2042/53184, 2014.
Ricaud, P. : Variabilités de la vapeur d’eau et de la température troposphérique mesurées par le radiomètre micro-onde HAMSTRAD au Dôme C, Antarctique. Partie II : Résultats scientifiques, La Météorologie, 85, 35-46, doi:10.4267/2042/53749, 2014.
Ricaud, P., Carminati, F., Attié, J.-L., Courcoux, Y., Rose, T., Genthon, C., Pellegrini, A., Tremblin, P. and August, T. : Quality Assessment of the First Measurements of Tropospheric Water Vapour and Temperature by the HAMSTRAD Radiometer over Concordia Station, Antarctica. IEEE Transactions on Geoscience and Remote Sensing, 51, 3217–3239, doi:10.1109/TGRS.2012.2225627, 2013.
Sims, G., M. C. B. Ashley, X. Cui, J. R. Everett, L. Feng, X. Gong, S. Hengst, Z. Hu, C. Kulesa, J. S. Lawrence, D. M. Luong-Van, P. Ricaud, Z. Shang, J. W. V. Storey, L. Wang, H. Yang, J. Yang, X. Zhou, and Z. Zhu : Precipitable Water Vapor above Dome A, Antarctica, Determined from Diffuse Optical Sky Spectra, Publications of the astronomical society of the pacific, 124(911), 74-83, 2012.
Ricaud, P., Genthon, C., Durand, P., Attié, J.-L., Carminati, F., Canut, G., Vanacker, J.-F., Moggio, L., Courcoux, Y., Pellegrini, A. and Rose, T. : Summer to Winter Diurnal Variabilities of Temperature and Water Vapour in the lowermost troposphere as observed by the HAMSTRAD Radiometer over Dome C, Antarctica. Boundary-Layer Meteorology, 143, 227–259, doi:10.1007/s10546-011-9673-6, 2012.
Tremblin, P., Minier, V., Schneider, N., Durand, G.Al., Ashley, M.C.B., Lawrence, J.S., Luong-van, D.M., Storey, J.W.V., Durand, G.An., Reinert, Y., Veyssiere, C., Walter, C., Ade, P., Calisse, P.G., Challita, Z., Fossat, E., Sabbatini, L., Pellegrini, A., Ricaud, P. and Urban, J. : Site testing for submillimetre astronomy at Dome C in Antarctica. Astronomy and Astrophysics, 535, doi:10.1051/0004-6361/201117345, 2011.
Ricaud, P., Gabard, B., Derrien, S., Chaboureau, J.-P., Rose, T., Mombauer, A. and Czekala, H. : HAMSTRAD-Tropo, A 183-GHz Radiometer Dedicated to Sound Tropospheric Water Vapour Over Concordia Station, Antarctica. IEEE Transactions on Geoscience and Remote Sensing, 48, 1365–1380, doi:10.1109/TGRS.2009.2029345, 2010.
Ricaud, P., Gabard, B., Derrien, S., Attié, J.-L., Rose, T. and Czekala, H. : Validation of Tropospheric Water Vapour as Measured by the 183-GHz HAMSTRAD Radiometer Over the Pyrennees Mountains, France. IEEE Transactions on Geoscience and Remote Sensing, 48, 2189–2203, 2010.