Review of tropospheric temperature, absolute humidity and integrated water vapour from the HAMSTRAD radiometer installed at Dome C, Antarctica, 2009–14

AbstractThe HAMSTRAD (H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) instrument is a microwave radiometer installed at Dome C (Antarctica, 75°06'S, 123°21'E, 3233 m a.m.s.l.) dedicated to the tropospheric measurements of temperature, absolute humidity and integrated water vapour (IWV). The aim of the present paper is to review the entire HAMSTRAD dataset from 2009 to 2014 with a 7-minute integration time from 0 to 10 km by comparison with coincident radiosondes launched at 12h00 UTC at Dome C. Based upon an extensive evaluation of biases and time correlation coefficients (r), we can state: i) IWV is of excellent quality (r>0.98) and can be used without retrieving significant bias, ii) temperature is suitable for scientific analyses over 0–10 km with a high time correlation with radiosondes (r>0.80) and iii) absolute humidity is suitable for scientific analyses over 0–4 km with a moderate time correlation against radiosondes (r>0.70). The vertical distribution of temperature (0–10 km) and absolute humidity (0–4 km) is subject to biases that need to be removed if the analyses require the use of vertical profiling. The HAMSTRAD dataset is provided in open access to the scientific community.

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Statistical analyses and correlation between tropospheric temperature and humidity at Dome C, Antarctica

Antarctic Science ◽

10.1017/s0954102013000564 ◽

2013 ◽

Vol 26 (3) ◽

pp. 290-308 ◽

Cited By ~ 4

Author(s):

P. Ricaud ◽

F. Carminati ◽

Y. Courcoux ◽

A. Pellegrini ◽

J.-L. Attié ◽

...

Keyword(s):

Water Vapour ◽

Pearson Correlation ◽

Microwave Radiometer ◽

Weather Forecast ◽

Tropospheric Temperature ◽

Infrared Sensors ◽

Atmospheric Infrared Sounder ◽

Medium Range Weather Forecast ◽

Integrated Water Vapour ◽

Highly Correlated

AbstractThe Dome C (Concordia) station in Antarctica (75°06′S, 123°21′E, 3233 m above mean sea level) has a unique opportunity to test the quality of remote-sensing measurements and meteorological analyses because it is situated well inside the Eastern Antarctic Plateau and is less affected by local phenomena. Measurements of tropospheric temperature and water vapour (H2O) together with the integrated water vapour (IWV) performed in 2010 are statistically analysed to assess their quality and to study the yearly correlation between temperature and H2O over the entire troposphere. The statistical tools include yearly evolution, seasonally-averaged mean and bias, standard deviation and linear Pearson correlation. The datasets are made of measurements from the ground-based microwave radiometer H2O Antarctica Microwave Stratospheric and Tropospheric Radiometer (HAMSTRAD), radiosonde, in situ sensors, the space-borne infrared sensors Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp-A platform and the Atmospheric InfraRed Sounder (AIRS) on the Aqua platform, and the analyses from the European Centre for Medium-Range Weather Forecast (ECMWF). Despite some obvious biases within all these datasets, our study shows that temperature and IWV are generally measured with high quality whilst H2O measurement quality is slightly worse. The AIRS and IASI measurements do not have the vertical resolution to correctly probe the lowermost troposphere, whilst HAMSTRAD loses sensitivity in the upper troposphere-lower stratosphere. Within the entire troposphere over the whole year, it is found that the time evolution of temperature and H2O is highly correlated (> 0.8). This suggests that, in addition to the variability of solar radiation producing an obvious diurnal cycle in the planetary boundary layer in summer and an obvious seasonal cycle over the year, the H2O and temperature intra-seasonal variabilities are affected by the same processes, e.g. related to the long-range transport of air masses.

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Tropospheric water vapour above Switzerland over the last 12 years

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-5975-2009 ◽

2009 ◽

Vol 9 (16) ◽

pp. 5975-5988 ◽

Cited By ~ 28

Author(s):

J. Morland ◽

M. Collaud Coen ◽

K. Hocke ◽

P. Jeannet ◽

C. Mätzler

Keyword(s):

Time Series ◽

Water Vapour ◽

Grid Point ◽

Microwave Radiometer ◽

Regional Scale ◽

Seasonal Trends ◽

Climate Change Effects ◽

Integrated Water Vapour ◽

Mountain Weather

Abstract. Integrated Water vapour (IWV) has been measured since 1994 by the TROWARA microwave radiometer in Bern, Switzerland. Homogenization techniques were used to identify and correct step changes in IWV related to instrument problems. IWV from radiosonde, GPS and sun photometer (SPM) was used in the homogenisation process as well as partial IWV columns between valley and mountain weather stations. The average IWV of the homogenised TROWARA time series was 14.4 mm over the 1996–2007 period, with maximum and minimum monthly average values of 22.4 mm and 8 mm occurring in August and January, respectively. A weak diurnal cycle in TROWARA IWV was detected with an amplitude of 0.32 mm, a maximum at 21:00 UT and a minimum at 11:00 UT. For 1996–2007, TROWARA trends were compared with those calculated from the Payerne radiosonde and the closest ECMWF grid point to Bern. Using least squares analysis, the IWV time series of radiosondes at Payerne, ECMWF, and TROWARA showed consistent positive trends from 1996 to 2007. The radiosondes measured an IWV trend of 0.45±0.29%/y, the TROWARA radiometer observed a trend of 0.39±0.44%/y, and ECMWF operational analysis gave a trend of 0.25±0.34%/y. Since IWV has a strong and variable annual cycle, a seasonal trend analysis (Mann-Kendall analysis) was also performed. The seasonal trends are stronger by a factor 10 or so compared to the full year trends above. The positive IWV trends of the summer months are partly compensated by the negative trends of the winter months. The strong seasonal trends of IWV on regional scale underline the necessity of long-term monitoring of IWV for detection,understanding, and forecast of climate change effects in the Alpine region.

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Water vapour retrieval using the Precision Solar Spectroradiometer

Atmospheric Measurement Techniques ◽

10.5194/amt-11-1143-2018 ◽

2018 ◽

Vol 11 (2) ◽

pp. 1143-1157 ◽

Cited By ~ 4

Author(s):

Panagiotis-Ioannis Raptis ◽

Stelios Kazadzis ◽

Julian Gröbner ◽

Natalia Kouremeti ◽

Lionel Doppler ◽

...

Keyword(s):

Water Vapour ◽

Single Channel ◽

Microwave Radiometer ◽

Coefficient Of Determination ◽

High Temporal Resolution ◽

Spectral Approach ◽

Spectral Measurements ◽

Data Set ◽

Integrated Water Vapour ◽

Relative Differences

Abstract. The Precision Solar Spectroradiometer (PSR) is a new spectroradiometer developed at Physikalisch-Meteorologisches Observatorium Davos – World Radiation Center (PMOD–WRC), Davos, measuring direct solar irradiance at the surface, in the 300–1020 nm spectral range and at high temporal resolution. The purpose of this work is to investigate the instrument's potential to retrieve integrated water vapour (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV: the first one uses single-channel and wavelength measurements, following a theoretical water vapour high absorption wavelength, and the second one uses direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year data set, consisting of an AERONET sun-photometer Cimel CE318, a Global Positioning System (GPS), a microwave radiometer profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods and instruments was achieved using the 946 nm channel, while for the spectral approach the 934–948 nm window was used. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R2) being in the region of 0.87–0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R2 in the region of 0.96–0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08–0.30 cm and only in extreme cases would reach up to 15 %.

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Tropospheric water vapour above Switzerland over the last 12 years

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-7239-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 7239-7271 ◽

Cited By ~ 3

Author(s):

J. Morland ◽

M. Collaud Coen ◽

K. Hocke ◽

P. Jeannet ◽

C. Mätzler

Keyword(s):

Water Vapour ◽

Grid Point ◽

Microwave Radiometer ◽

Negative Trend ◽

Positive Trend ◽

Significant Positive Trend ◽

Significant Negative Trend ◽

Integrated Water Vapour ◽

Weather Stations ◽

Homogenisation Process

Abstract. Integrated Water vapour (IWV) has been measured since 1994 by the TROWARA microwave radiometer in Bern, Switzerland. Homogenization techniques were used to identify and correct step changes in IWV related to instrument problems. IWV from radiosonde, GPS and SPM was used in the homogenisation process as well as the IWV differences calculated between mountain and valley weather stations. The average IWV of the homogenised TROWARA time series was 14.4 mm over the 1996–2007 period, with maximum and minimum monthly average values of 22.4 mm and 8 mm occurring in August and January, respectively. A weak diurnal cycle in TROWARA IWV was detected with an amplitude of 0.32 mm, a maximum at 21:00 UT and a minimum at 11:00 UT. For 1996–2007, TROWARA trends were compared with those calculated from the Payerne radiosonde and the closest ECMWF grid point to Bern. The radiosonde midnight trend of +0.087 (standard error 0.046) mm/y was significant at the 90% level. The radiosonde trend for all measurement times, +0.098 (0.061) mm/y, and the TROWARA midday trends, 0.068 (0.043) mm/y, were significant at the 89% level. Seasonal Mann Kendall analysis revealed a significant positive trend in July of +0.19 (0.14) to +0.34 (0.25) mm/y for all three datasets. In December, the Payerne radiosonde showed a non-significant negative trend of −0.12 (0.13) mm/y, whilst ECMWF and TROWARA indicated a significant negative trend of −0.20 (0.14) and −0.36 (0.24) mm/y, respectively.

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Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

Atmospheric Measurement Techniques ◽

10.5194/amt-10-4521-2017 ◽

2017 ◽

Vol 10 (11) ◽

pp. 4521-4536 ◽

Cited By ~ 6

Author(s):

Yana A. Virolainen ◽

Yury M. Timofeyev ◽

Vladimir S. Kostsov ◽

Dmitry V. Ionov ◽

Vladislav V. Kalinnikov ◽

...

Keyword(s):

Quality Assessment ◽

Water Vapour ◽

Measurement Errors ◽

Microwave Radiometer ◽

Reference Method ◽

Atmospheric Conditions ◽

Assessment Protocol ◽

Clear Sky ◽

Integrated Water Vapour ◽

Sky Conditions

Abstract. The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

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A multi-instrument comparison of integrated water vapour measurements at a high latitude site

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-10925-2012 ◽

2012 ◽

Vol 12 (22) ◽

pp. 10925-10943 ◽

Cited By ~ 37

Author(s):

S. A. Buehler ◽

S. Östman ◽

C. Melsheimer ◽

G. Holl ◽

S. Eliasson ◽

...

Keyword(s):

Water Vapour ◽

Microwave Radiometer ◽

Reanalysis Data ◽

Data Set ◽

Lower Altitude ◽

Integrated Water Vapour ◽

Ftir Spectrometer ◽

The Impact ◽

Instrument Comparison ◽

Temporal Coverage

Abstract. We compare measurements of integrated water vapour (IWV) over a subarctic site (Kiruna, Northern Sweden) from five different sensors and retrieval methods: Radiosondes, Global Positioning System (GPS), ground-based Fourier-transform infrared (FTIR) spectrometer, ground-based microwave radiometer, and satellite-based microwave radiometer (AMSU-B). Additionally, we compare also to ERA-Interim model reanalysis data. GPS-based IWV data have the highest temporal coverage and resolution and are chosen as reference data set. All datasets agree reasonably well, but the ground-based microwave instrument only if the data are cloud-filtered. We also address two issues that are general for such intercomparison studies, the impact of different lower altitude limits for the IWV integration, and the impact of representativeness error. We develop methods for correcting for the former, and estimating the random error contribution of the latter. A literature survey reveals that reported systematic differences between different techniques are study-dependent and show no overall consistent pattern. Further improving the absolute accuracy of IWV measurements and providing climate-quality time series therefore remain challenging problems.

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Quality assessment of integrated water vapour measurements at St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

10.5194/amt-2017-135 ◽

2017 ◽

Author(s):

Yana A. Virolainen ◽

Yury M. Timofeyev ◽

Vladimir S. Kostsov ◽

Dmitry V. Ionov ◽

Vladislav V. Kalinnikov ◽

...

Keyword(s):

Quality Assessment ◽

Water Vapour ◽

Measurement Errors ◽

Microwave Radiometer ◽

Satellite System ◽

Data Sets ◽

Atmospheric Conditions ◽

Assessment Protocol ◽

Integrated Water Vapour ◽

Global Navigation Satellite

Abstract. The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by Fourier-transform infrared spectrometer Bruker 125 HR (FTIR), microwave radiometer RPG-HATPRO (MW) and global navigation satellite system receiver Novatel ProPak-V3 (GPS) at St. Petersburg site between August 2014 and October 2016. Generally, all three techniques agree well with each other and therefore are suitable for monitoring IWV values at St. Petersburg site. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.33 ± 0.03 mm (2.0 ± 0.3 %), 0.54 ± 0.03 mm (4.5 ± 0.3 %), and 0.76 ± 0.04 mm (6.3 ± 0.7 %) for FTIR, GPS and MW methods, respectively. We conclude that accurate spatial and temporal matching of different IWV measurements is necessary for achieving the better agreement between various methods for IWV monitoring.

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Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-6567-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 6567-6599 ◽

Cited By ~ 2

Author(s):

A. Foth ◽

H. Baars ◽

P. Di Girolamo ◽

B. Pospichal

Keyword(s):

Water Vapour ◽

Continuous Measurement ◽

Microwave Radiometer ◽

Calibration Method ◽

Calibration Factor ◽

Raman Lidar ◽

Clear Sky ◽

Lidar Measurements ◽

Integrated Water Vapour ◽

Good Agreement

Abstract. In this paper, we present a method to derive water vapour profiles from Raman lidar measurements calibrated by the integrated water vapour (IWV) from a collocated microwave radiometer during the intense observation campaign HOPE in the frame of the HD(CP)2 initiative. The simultaneous observation of a microwave radiometer and a Raman lidar allowed an operational and continuous measurement of water vapour profiles also during cloudy conditions. The calibration method provides results in a good agreement with conventional methods based on radiosondes. The calibration factor derived from the proposed IWV method is very stable with a relative uncertainty of 6%. This stability allows to calibrate the lidar even in the presence of clouds using the calibration factor determined during the closest in time clear sky interval. Based on the application of this approach, it is possible to retrieve water vapour profiles during all non-precipitating conditions. A statistical analysis shows a good agreement between the lidar measurements and collocated radiosondes. The relative biases amount to less than 6.7% below 2 km.

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A multi-instrument comparison of integrated water vapour measurements at a high latitude site

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-21013-2012 ◽

2012 ◽

Vol 12 (8) ◽

pp. 21013-21063 ◽

Cited By ~ 1

Author(s):

S. A. Buehler ◽

S. Östman ◽

C. Melsheimer ◽

G. Holl ◽

S. Eliasson ◽

...

Keyword(s):

Water Vapour ◽

Microwave Radiometer ◽

Reanalysis Data ◽

Data Set ◽

Lower Altitude ◽

Integrated Water Vapour ◽

Ftir Spectrometer ◽

The Impact ◽

Instrument Comparison ◽

Temporal Coverage

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Quantifying the value of redundant measurements at GCOS Reference Upper-Air Network sites

Atmospheric Measurement Techniques ◽

10.5194/amt-7-3813-2014 ◽

2014 ◽

Vol 7 (11) ◽

pp. 3813-3823 ◽

Cited By ~ 3

Author(s):

F. Madonna ◽

M. Rosoldi ◽

J. Güldner ◽

A. Haefele ◽

R. Kivi ◽

...

Keyword(s):

Time Series ◽

Water Vapour ◽

Global Climate ◽

Microwave Radiometer ◽

Raman Lidar ◽

Mutual Correlation ◽

Random Uncertainty ◽

Lidar Measurements ◽

Integrated Water Vapour ◽

Microwave Radiometers

Abstract. The potential for measurement redundancy to reduce uncertainty in atmospheric variables has not been investigated comprehensively for climate observations. We evaluated the usefulness of entropy and mutual correlation concepts, as defined in information theory, for quantifying random uncertainty and redundancy in time series of the integrated water vapour (IWV) and water vapour mixing ratio profiles provided by five highly instrumented GRUAN (GCOS, Global Climate Observing System, Reference Upper-Air Network) stations in 2010–2012. Results show that the random uncertainties on the IWV measured with radiosondes, global positioning system, microwave and infrared radiometers, and Raman lidar measurements differed by less than 8%. Comparisons of time series of IWV content from ground-based remote sensing instruments with in situ soundings showed that microwave radiometers have the highest redundancy with the IWV time series measured by radiosondes and therefore the highest potential to reduce the random uncertainty of the radiosondes time series. Moreover, the random uncertainty of a time series from one instrument can be reduced by ~ 60% by constraining the measurements with those from another instrument. The best reduction of random uncertainty is achieved by conditioning Raman lidar measurements with microwave radiometer measurements. Specific instruments are recommended for atmospheric water vapour measurements at GRUAN sites. This approach can be applied to the study of redundant measurements for other climate variables.

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