scholarly journals Validation of middle atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C

2013 ◽  
Vol 6 (1) ◽  
pp. 1311-1359 ◽  
Author(s):  
B. Tschanz ◽  
C. Straub ◽  
D. Scheiben ◽  
K. A. Walker ◽  
G. P. Stiller ◽  
...  
Keyword(s):  
Water Vapour ◽  
Random Error ◽  
Microwave Radiometer ◽  
Incident Radiation ◽  
Temporal Variations ◽  
The Arctic ◽  
Atmospheric Water ◽  
Data Set ◽  
Atmospheric Water Vapour ◽  
Measurement Campaigns

Abstract. Middle atmospheric water vapour can be used as a tracer for dynamical processes. It is mainly measured by satellite instruments and ground-based microwave radiometers. Ground-based instruments capable of measuring middle atmospheric water vapour are sparse but valuable as they complement satellite measurements, are relatively easy to maintain and have a long lifetime. MIAWARA-C is a ground-based microwave radiometer for middle atmospheric water vapour designed for use on measurement campaigns for both atmospheric case studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1 (v1.1) is set up in a way to provide a consistent data set even if the instrument is operated from different locations on a campaign basis. The sensitive altitude range for v1.1 extends from 4 hPa (37 km) to 0.017 hPa (75 km). MIAWARA-C measures two polarisations of the incident radiation in separate receiver channels and can therefore provide two independent measurements of the same air mass. The standard deviation of the difference between the profiles obtained from the two polarisations is in excellent agreement with the estimated random error of v1.1. In this paper, the quality of v1.1 data is assessed during two measurement campaigns: (1) five months of measurements in the Arctic (Sodankylä, 67.37° N/26.63° E) and (2) nine months of measurements at mid-latitudes (Zimmerwald, 46.88° N/7.46° E). For both campaigns MIAWARA-C's profiles are compared to measurements from the satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS and SOFIE are presented for the Arctic and to the ground-based radiometer MIAWARA for the mid-latitudinal campaign. In general all intercomparisons show high correlation coefficients, above 0.5 at altitudes above 45 km, confirming the ability of MIAWARA-C to monitor temporal variations on the order of days. The biases are generally below 10% and within the estimated systematic uncertainty of MIAWARA-C. No consistent wet or dry bias is identified for MIAWARA-C. In addition, comparisons to the reference instruments indicate the estimated random error of v1.1 to be a realistic measure of the random variation on the retrieved profile.

scholarly journals Validation of middle-atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C

2013 ◽  
Vol 6 (7) ◽  
pp. 1725-1745 ◽  
Author(s):  
B. Tschanz ◽  
C. Straub ◽  
D. Scheiben ◽  
K. A. Walker ◽  
G. P. Stiller ◽  
...  
Keyword(s):  
Water Vapour ◽  
Random Error ◽  
Microwave Radiometer ◽  
Incident Radiation ◽  
Temporal Variations ◽  
The Arctic ◽  
Atmospheric Water ◽  
Random Measurement Error ◽  
Data Set ◽  
Atmospheric Water Vapour

Abstract. Middle atmospheric water vapour can be used as a tracer for dynamical processes. It is mainly measured by satellite instruments and ground-based microwave radiometers. Ground-based instruments capable of measuring middle-atmospheric water vapour are sparse but valuable as they complement satellite measurements, are relatively easy to maintain and have a long lifetime. MIAWARA-C is a ground-based microwave radiometer for middle-atmospheric water vapour designed for use on measurement campaigns for both atmospheric case studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1 (v1.1) is set up in a such way as to provide a consistent data set even if the instrument is operated from different locations on a campaign basis. The sensitive altitude range for v1.1 extends from 4 hPa (37 km) to 0.017 hPa (75 km). For v1.1 the estimated systematic error is approximately 10% for all altitudes. At lower altitudes it is dominated by uncertainties in the calibration, with altitude the influence of spectroscopic and temperature uncertainties increases. The estimated random error increases with altitude from 5 to 25%. MIAWARA-C measures two polarisations of the incident radiation in separate receiver channels, and can therefore provide two measurements of the same air mass with independent instrumental noise. The standard deviation of the difference between the profiles obtained from the two polarisations is in excellent agreement with the estimated random measurement error of v1.1. In this paper, the quality of v1.1 data is assessed for measurements obtained at two different locations: (1) a total of 25 months of measurements in the Arctic (Sodankylä, 67.37° N, 26.63° E) and (2) nine months of measurements at mid-latitudes (Zimmerwald, 46.88° N, 7.46° E). For both locations MIAWARA-C's profiles are compared to measurements from the satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS and SOFIE are presented for the Arctic and to the ground-based radiometer MIAWARA for the mid-latitude campaigns. In general, all intercomparisons show high correlation coefficients, confirming the ability of MIAWARA-C to monitor temporal variations of the order of days. The biases are generally below 13% and within the estimated systematic uncertainty of MIAWARA-C. No consistent wet or dry bias is identified for MIAWARA-C. In addition, comparisons to the reference instruments indicate the estimated random error of v1.1 to be a realistic measure of the random variation on the retrieved profile between 45 and 70 km.

scholarly journals Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies

2016 ◽  
Vol 34 (7) ◽  
pp. 623-639 ◽  
Author(s):  
Clara Eugenia Bianchi ◽  
Luciano Pedro Oscar Mendoza ◽  
Laura Isabel Fernández ◽  
María Paula Natali ◽  
Amalia Margarita Meza ◽  
...  
Keyword(s):  
South America ◽  
Water Vapour ◽  
Weather Prediction ◽  
High Rate ◽  
Atmospheric Water ◽  
Total Delay ◽  
Data Set ◽  
Atmospheric Water Vapour ◽  
Climate Studies

Abstract. Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

The distribution and transport of atmospheric water vapour over the Arctic Basin

1995 ◽  
Vol 15 (7) ◽  
pp. 709-727 ◽  
Author(s):  
Mark C. Serreze ◽  
Mark C. Rehder ◽  
Roger G. Barry ◽  
Jonathan D. Kahl ◽  
Nina A. Zaitseva
Keyword(s):  
Water Vapour ◽  
Arctic Basin ◽  
The Arctic ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour

scholarly journals Retrieval of total water vapour in the Arctic using microwave humidity sounders

2018 ◽  
Vol 11 (4) ◽  
pp. 2067-2084 ◽  
Author(s):  
Raul Cristian Scarlat ◽  
Christian Melsheimer ◽  
Georg Heygster
Keyword(s):  
Water Vapour ◽  
Open Water ◽  
The Arctic ◽  
Measured Signal ◽  
Physical Analysis ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour ◽  
Microwave Emissivity ◽  
Spatial Coverage ◽  
Microwave Radiometers

Abstract. Quantitative retrievals of atmospheric water vapour in the Arctic present numerous challenges because of the particular climate characteristics of this area. Here, we attempt to build upon the work of Melsheimer and Heygster (2008) to retrieve total atmospheric water vapour (TWV) in the Arctic from satellite microwave radiometers. While the above-mentioned algorithm deals primarily with the ice-covered central Arctic, with this work we aim to extend the coverage to partially ice-covered and ice-free areas. By using modelled values for the microwave emissivity of the ice-free sea surface, we develop two sub-algorithms using different sets of channels that deal solely with open-ocean areas. The new algorithm extends the spatial coverage of the retrieval throughout the year but especially in the warmer months when higher TWV values are frequent. The high TWV measurements over both sea-ice and open-water surfaces are, however, connected to larger uncertainties as the retrieval values are close to the instrument saturation limits.This approach allows us to apply the algorithm to regions where previously no data were available and ensures a more consistent physical analysis of the satellite measurements by taking into account the contribution of the surface emissivity to the measured signal.

scholarly journals Retrieval of Total Water Vapour in the Arctic Using Microwave Humidity Sounders

2017 ◽  
Author(s):  
Raul Cristian Scarlat ◽  
Christian Melsheimer ◽  
Georg Heygster
Keyword(s):  
Water Vapour ◽  
The Arctic ◽  
Measured Signal ◽  
Physical Analysis ◽  
Atmospheric Water ◽  
Satellite Measurements ◽  
Atmospheric Water Vapour ◽  
Microwave Emissivity ◽  
Satellite Microwave ◽  
Microwave Radiometers

Abstract. Quantitative retrievals of atmospheric water vapour in the Arctic are faced with numerous challenges because of the particular climate characteristics of this area. Here, we attempt to build upon the work of Melsheimer and Heygster (2008) to retrieve total atmospheric water vapour (TWV) in the Arctic from satellite microwave radiometers. While the above mentioned algorithm deals primarily with the ice-covered central Arctic, with this work we are aiming to extend the coverage to low ice cover and ice-free areas. By using modeled values for the microwave emissivity of the ice-free sea surface, we develop two sub-algorithms using different sets of channels that deal solely with open ocean areas. This approach allows us to apply the algorithm to regions where previously no data were available and ensures a more consistent physical analysis of the satellite measurements by taking into account the contribution of the surface emissivity to the measured signal.

scholarly journals Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

2017 ◽  
Vol 10 (8) ◽  
pp. 2851-2880 ◽  
Author(s):  
Dan Weaver ◽  
Kimberly Strong ◽  
Matthias Schneider ◽  
Penny M. Rowe ◽  
Chris Sioris ◽  
...  
Keyword(s):  
Water Vapour ◽  
Global Climate ◽  
Microwave Radiometer ◽  
Correlation Coefficients ◽  
High Arctic ◽  
Atmospheric Water ◽  
Canadian High Arctic ◽  
Solar Absorption ◽  
Atmospheric Water Vapour ◽  
Ftir Spectrometer

Abstract. Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences  ≤  1.0 kg m−2 and correlation coefficients  ≥  0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within −5.2 % of GRUAN and −6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

scholarly journals Intercomparison of atmospheric water vapour measurements in the Canadian high Arctic

2016 ◽  
Author(s):  
Dan Weaver ◽  
Kimberly Strong ◽  
Matthias Schneider ◽  
Penny M. Rowe ◽  
Chris Sioris ◽  
...  
Keyword(s):  
Water Vapour ◽  
Microwave Radiometer ◽  
Correlation Coefficients ◽  
High Arctic ◽  
Atmospheric Water ◽  
Canadian High Arctic ◽  
Solar Absorption ◽  
Atmospheric Water Vapour ◽  
Retrieval Technique ◽  
Good Agreement

Abstract. Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian high Arctic research site. Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform spectrometers (FTSs). Good agreement is observed between all combination of datasets, with correlation coefficients ≥ 0.90 showing high correlations. A variety of biases and calibration issues are revealed and discussed for all instruments. A new FTS dataset, resulting from the MUSICA (Multi-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique, is shown to offer accurate measurements of water vapour total columns; however, measurements show a small wet bias of approximately 6 %. A new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is also shown to provide accurate water vapour measurements, which usefully enables measurements to be taken during day and night (especially valuable during Polar Night). In addition, limited profile comparisons are conducted using radiosonde and ground-based FTS measurements. Results show MUSICA FTS profiles were within 15 % of radiosonde measurements throughout the troposphere.

Atmospheric water vapour processing

Waterlines ◽  
1993 ◽  
Vol 12 (2) ◽  
pp. 20-22 ◽  
Author(s):  
Roland Wahlgren
Keyword(s):  
Water Vapour ◽  
Atmospheric Water ◽  
Atmospheric Water Vapour
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