The 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.
The Sub‐Millimetre Radiometer (SMR) on board the Odin satellite, launched on 20 February 2001, observes key species with respect to stratospheric chemistry and dynamics such as O3, ClO, N2O, and HNO3 ...using two bands centered at 501.8 and 544.6 GHz. We present the adopted methodology for level 2 processing and the achieved in‐orbit measurement capabilities of the SMR radiometer for these species in terms of altitude range, altitude resolution, and measurement precision. The characteristics of the relevant level 2 data versions, namely version 1.2 of the operational processor as well as versions 222 and 223 of the reference code, are discussed and differences are evaluated. An analysis of systematic retrieval errors, resulting from spectroscopic and instrumental uncertainties, is also presented.
Validation results from a comparison between Measurement Of Pollution In The Troposphere (MOPITT) V5 Near InfraRed (NIR) carbon monoxide (CO) total column measurements and Measurement of Ozone and ...Water Vapour on Airbus in-service Aircraft (MOZAIC)/In-Service Aircraft for a Global Observing System (IAGOS) aircraft measurements are presented. A good agreement is found between MOPITT and MOZAIC/IAGOS measurements, consistent with results from earlier studies using different validation data and despite large variability in MOPITT CO total columns along the spatial footprint of the MOZAIC/IAGOS measurements. Validation results improve when taking the large spatial footprint of the MOZAIC/IAGOS data into account. No statistically significant drift was detected in the validation results over the period 2002–2010 at global, continental and local (airport) scales. Furthermore, for those situations where MOZAIC/IAGOS measurements differed from the MOPITT a priori, the MOPITT measurements clearly outperformed the MOPITT a priori data, indicating that MOPITT NIR retrievals add value to the MOPITT a priori. Results from a high spatial resolution simulation of the chemistry-transport model MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) showed that the most likely explanation for the large MOPITT variability along the MOZAIC-IAGOS profile flight path is related to spatio-temporal CO variability, which should be kept in mind when using MOZAIC/IAGOS profile measurements for validating satellite nadir observations.
Ozone is a tropospheric pollutant and plays a key role in determining the air quality that affects human wellbeing. In this study, we compare the capability of two hypothetical grating spectrometers ...onboard a geostationary (GEO) satellite to sense ozone in the lowermost troposphere (surface and the 0–1 km column). We consider 1 week during the Northern Hemisphere summer simulated by a chemical transport model, and use the two GEO instrument configurations to measure ozone concentration (1) in the thermal infrared (GEO TIR) and (2) in the thermal infrared and the visible (GEO TIR+VIS). These configurations are compared against each other, and also against an ozone reference state and a priori ozone information. In a first approximation, we assume clear sky conditions neglecting the influence of aerosols and clouds. A number of statistical tests are used to assess the performance of the two GEO configurations. We consider land and sea pixels and whether differences between the two in the performance are significant. Results show that the GEO TIR+VIS configuration provides a better representation of the ozone field both for surface ozone and the 0–1 km ozone column during the daytime especially over land.
The HAMSTRAD (H
2
O Antarctica Microwave Stratospheric and Tropospheric Radiometers) microwave radiometer operating at 60 GHz (oxygen line, thus temperature) and 183 GHz (water vapour line) has been ...permanently deployed at the Dome C station, Concordia, Antarctica 75°06′S, 123°21′E, 3,233 m above mean sea level in January 2010 to study long-term trends in tropospheric absolute humidity and temperature. The great sensitivity of the instrument in the lowermost troposphere helped to characterize the diurnal cycle of temperature and H
2
O from the austral summer (January 2010) to the winter (June 2010) seasons from heights of 10 to 200 m in the planetary boundary layer (PBL). The study has characterized the vertical resolution of the HAMSTRAD measurements: 10–20 m for temperature and 25–50 m for H
2
O. A strong diurnal cycle in temperature and H
2
O (although noisier) has been measured in summertime at 10 m, decreasing in amplitude with height, and phase-shifted by about 4 h above 50 m with a strong H
2
O–temperature correlation (>0.8) throughout the entire PBL. In autumn, whilst the diurnal cycle in temperature and H
2
O is less intense, a 12-h phase shift is observed above 30 m. In wintertime, a weak diurnal signal measured between 10 to 200 m is attributed to the methodology employed, which consists of monthly averaged data, and that combines air masses from different origins (sampling effect) and not to the imprint of the null solar irradiation. In situ sensors scanning the entire 24-h period, radiosondes launched at 2000 local solar time (LST) and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at 0200, 0800, 1400 and 2000 LST agree very well with the HAMSTRAD diurnal cycles for temperature and relatively well for absolute humidity. For temperature, HAMSTRAD tends to be consistent with all the other datasets but shows a smoother vertical profile from 10 to 100 m compared to radiosondes and in-situ data, with ECMWF profiles even smoother than HAMSTRAD profiles, and particularly obvious when moving from summer to winter. For H
2
O, HAMSTRAD measures a much moister atmosphere compared to all the other datasets with a much weaker diurnal cycle at 10 m. Our study has helped characterize the time variation of the PBL at Dome C with a top around 200 m in summertime decreasing to 30 m in wintertime. In summer, from 2000 to 0600 LST a stable layer is observed, followed by a well-mixed layer the remaining time, while only a nocturnal stable layer remains in winter. In autumn, a daytime convective layer shallower than the nocturnal stable layer develops.
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