scholarly journals Humidity observations in the Arctic troposphere over Ny-Ålesund, Svalbard based on 15 years of radiosonde data

2007 ◽  
Vol 7 (10) ◽  
pp. 2721-2732 ◽  
Author(s):  
R. Treffeisen ◽  
R. Krejci ◽  
J. Ström ◽  
A. C. Engvall ◽  
A. Herber ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Low Temperatures ◽  
The Arctic ◽  
Radiosonde Data ◽  
Radiative Balance ◽  
Seasonal Behaviour ◽  
Humidity Measurements ◽  
Characteristic Features ◽  
Humidity Profiles

Abstract. Water vapour is an important component in the radiative balance of the polar atmosphere. We present a study covering fifteen years of data of tropospheric humidity profiles measured with standard radiosondes at Ny-Ålesund (78°55' N 11°52' E) during the period from 1991 to 2006. It is well-known that relative humidity measurements are less reliable at low temperatures when measured with standard radiosondes. The data was corrected for errors and used to determine key characteristic features of the vertical and temporal relative humidity evolution in the Arctic troposphere over Ny-Ålesund. We present frequencies of occurrence of ice-supersaturation layers in the troposphere, their vertical span, temperature and statistical distribution. Supersaturation with respect to ice shows a clear seasonal behaviour. In winter, (October–February) it occurred in 19% of all cases and less frequently in spring (March–May 12%), and summer (June–September, 9%). Finally, the results are compared with findings from the SAGE II satellite instrument on subvisible clouds.

scholarly journals Humidity observations in the Arctic troposphere over Ny-Ålesund, Svalbard based on 14 years of radiosonde data

2007 ◽  
Vol 7 (1) ◽  
pp. 1261-1293 ◽  
Author(s):  
R. Treffeisen ◽  
R. Krejci ◽  
J. Ström ◽  
A. C. Engvall ◽  
A. Herber ◽  
...  
Keyword(s):  
Relative Humidity ◽  
The Arctic ◽  
Radiosonde Data ◽  
Cold Temperatures ◽  
Radiative Balance ◽  
Seasonal Behaviour ◽  
Humidity Measurements ◽  
Characteristic Features ◽  
Frequency Occurrence ◽  
Humidity Profiles

Abstract. Water vapour is an important component in the radiative balance of the polar atmosphere. We present a study covering fourteen-years of data of tropopsheric humidity profiles measured with standard radiosondes at Ny-Ålesund (78°55' N 11°52' E) during the period from 1991 to 2005. It is well known that relative humidity measurements are less reliable at cold temperatures when measured with standard radiosondes. The data were corrected for errors and used to determine key characteristic features of the vertical and temporal RH evolution in the Arctic troposphere over Ny-Ålesund. We present frequency occurrence of ice-supersaturation layers in the troposphere, their vertical span, temperature and statistical distribution. Supersaturation with respect to ice shows a clear seasonal behaviour. In winter (October–February) it occurred in 22% of all cases and less frequently in spring (March–May 13%), and summer (June–September, 10%). The results are finally compared with findings from the SAGE II satellite instrument on subvisible clouds.

scholarly journals Tropospheric water vapour and relative humidity profiles from lidar and microwave radiometry

2014 ◽  
Vol 7 (5) ◽  
pp. 1201-1211 ◽  
Author(s):  
F. Navas-Guzmán ◽  
J. Fernández-Gálvez ◽  
M. J. Granados-Muñoz ◽  
J. L. Guerrero-Rascado ◽  
J. A. Bravo-Aranda ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Microwave Radiometer ◽  
Radiosonde Data ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Night Time ◽  
New Approach ◽  
Lidar Measurements ◽  
Humidity Profiles

Abstract. In this paper, we outline an iterative method to calibrate the water vapour mixing ratio profiles retrieved from Raman lidar measurements. Simultaneous and co-located radiosonde data are used for this purpose and the calibration results obtained during a radiosonde campaign in summer and autumn 2011 are presented. The water vapour profiles measured during night-time by the Raman lidar and radiosondes are compared and the differences between the methodologies are discussed. Then, a new approach to obtain relative humidity profiles by combination of simultaneous profiles of temperature (retrieved from a microwave radiometer) and water vapour mixing ratio (from a Raman lidar) is addressed. In the last part of this work, a statistical analysis of water vapour mixing ratio and relative humidity profiles obtained during 1 year of simultaneous measurements is presented.

scholarly journals Inter-Comparison of AIRS Temperature and Relative Humidity Profiles with AMMA and DACCIWA Radiosonde Observations over West Africa

2020 ◽  
Vol 12 (16) ◽  
pp. 2631
Author(s):  
Marian Amoakowaah Osei ◽  
Leonard Kofitse Amekudzi ◽  
Craig R. Ferguson ◽  
Sylvester Kojo Danuor
Keyword(s):  
Relative Humidity ◽  
West Africa ◽  
Water Vapour ◽  
Radiosonde Data ◽  
Weather Information ◽  
Significant Difference ◽  
High Impact Weather ◽  
Mean Square Difference ◽  
June July ◽  
Humidity Profiles

The vertical profiles of temperature and water vapour from the Atmospheric InfraRed Sounder (AIRS) have been validated across various regions of the globe as an effort to provide a substitute for radiosonde observations. However, there is a paucity of inter-comparisons over West Africa where local convective processes dominate and radiosonde observations (RAOBs) are limited. This study validates AIRS temperature and relative humidity profiles for selected radiosonde stations in West Africa. Radiosonde data were obtained from the AMMA and DACCIWA campaigns which spanned 2006–2008 and June–July 2016 respectively and offered a period of prolonged radiosonde observations in West Africa. AIRS performance was evaluated with the bias and root mean square difference (RMSD) at seven RAOB stations which were grouped into coastal and inland. Evaluation was performed on diurnal and seasonal timescales, cloud screening conditions and derived thunderstorm instability indices. At all timescales, the temperature RMSD was higher than the AIRS accuracy mission goal of ±1 K. Relative humidity RMSD was satisfactory with deviations <20% and <50% for both lower and upper troposphere respectively. AIRS retrieval of water vapour under cloudy and cloud-free conditions had no significant difference whereas cloud-free temperature was found to be more accurate. The seasonal evolution of some thunderstorm convective indices were also found to be comparable for AIRS and RAOB. The ability of AIRS to capture the evolution of these indices imply it will be a useful dataset for the African Science for Weather Information and Forecasting Techniques (SWIFT) high impact weather studies.

scholarly journals Tropospheric water vapour and relative humidity profiles from lidar and microwave radiometry

2013 ◽  
Vol 6 (6) ◽  
pp. 10481-10510
Author(s):  
F. Navas-Guzmán ◽  
J. Fernández-Gálvez ◽  
M. J. Granados-Muñoz ◽  
J. L. Guerrero-Rascado ◽  
J. A. Bravo-Aranda ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Microwave Radiometer ◽  
Radiosonde Data ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
New Approach ◽  
Lidar Measurements ◽  
One Year ◽  
Humidity Profiles

Abstract. In this paper, we outline an iterative method to calibrate the water vapour mixing ratio profiles retrieved from Raman lidar measurements. Simultaneous and co-located radiosonde data are used for this purpose and the calibration results obtained during a radiosonde campaign performed in Summer and Autumn 2011 are presented. The water vapour profiles measured during nighttime by the Raman lidar and radiosondes are compared and the differences between the methodologies are discussed. Moreover, a new approach to obtain relative humidity profiles by combination of simultaneous profiles of temperature (retrieved from a microwave radiometer) and water vapour mixing ratio (from a Raman lidar) is addressed. In the last part of this work, a statistical analysis of water vapour mixing ratio and relative humidity profiles obtained during one year of simultaneous measurements is presented.

scholarly journals Índices termodinâmicos durante a campanha GOAmazon2014/5 e comparação com dados da reanálise ERA-Interim

2020 ◽  
Vol 42 ◽  
pp. e19
Author(s):  
Matheus Tolentino da Silva ◽  
Henrique De Melo Jorge Barbosa ◽  
Theotonio Mendes Pauliquevis Júnior
Keyword(s):  
Relative Humidity ◽  
Dry Season ◽  
Amazon Rainforest ◽  
Cloud Formation ◽  
Radiosonde Data ◽  
Radiative Balance ◽  
Thermodynamic Conditions ◽  
The Difference ◽  
Seasonal Analysis ◽  
Humidity Profiles

The thermodynamic indexes LCL, LFC, CINE and CAPE characterize atmospheric instability, and allow the study of cloud formation and convection, important phenomena for the hydrologic cycle and the radiative balance. For this reason, this work makes a seasonal analysis of these thermodynamic indexes computed from radiosondes released during the GOAmazon2014/5 experiment. A comparison was made with ERA-Interim reanalysis for both these indexes and the temperature and relative humidity profiles. Analysis of radiosonde data shows that the median vertical profile of relative humidity in the dry season was lower in 2015 when compared to 2014, resulting in higher LCL (~50 hPa at 18 Z) and lower CAPE (~50% lower). The difference stems from a more severe dry season in 2015 when compared with 2014. The comparison with the reanalysis reveals that modeled LCL values are only compatible with observed ones at 18 Z (mean bias -10 hPa). On the other hand, CAPE values are always incompatible (mean bias -750 j/kg). Results indicate that ERA Interim poorly represents the thermodynamic conditions over the Amazon rainforest.

Estimation of fine-scale relative humidity profiles: an issue for understanding the atmospheric water cycle

2020 ◽  
Author(s):  
Veronique Michot ◽  
Helene Brogniez ◽  
Mathieu Vrac ◽  
Soulivanh Thao ◽  
Helene Chepfer ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Quantile Regression ◽  
Water Vapour ◽  
Climate Models ◽  
Water Cycle ◽  
Skill Score ◽  
Horizontal Resolution ◽  
Atmospheric Water ◽  
Global Knowledge ◽  
Humidity Profiles

&lt;p&gt;The multi-scale interactions at the origin of the links between clouds and water vapour are essential for the Earth's energy balance and thus the climate, from local to global. Knowledge of the distribution and variability of water vapour in the troposphere is indeed a major issue for the understanding of the atmospheric water cycle. At present, these interactions are poorly known at regional and local scales, i.e. within 100km, and are therefore poorly represented in numerical climate models. This is why we have sought to predict cloud scale relative humidity profiles in the intertropical zone, using a non-parametric statistical downscaling method called quantile regression forest. The procedure includes co-located data from 3 satellites: CALIPSO lidar and CloudSat radar, used as predictors and providing cloud properties at 90m and 1.4km horizontal resolution respectively; SAPHIR data used as a predictor and providing relative humidity at an initial horizontal resolution of 10km. Quantile regression forests were used to predict relative humidity profiles at the CALIPSO and CloudSat scales. These predictions are able to reproduce a relative humidity variability consistent with the cloud profiles and are confirmed by values of coefficients of determination greater than 0.7, relative to observed relative humidity, and Continuous Rank Probability Skill Score between 0 and 1, relative to climatology. Lidar measurements from the NARVAL 1&amp;2 campaigns and radiosondes from the EUREC4A campaigns were also used to compare Relative Humidity profiles at the SAPHIR scale and at the scale of forest regression prediction by quantile regression.&lt;/p&gt;

Application of a Transient Method for Investigation of Water Vapour Transport Properties of Autoclaved Aerated Concrete

2015 ◽  
Vol 824 ◽  
pp. 95-99
Author(s):  
Jaromír Žumár ◽  
Zbyšek Pavlík ◽  
Robert Černý
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Inverse Analysis ◽  
Water Vapour Permeability ◽  
Diffusion Experiment ◽  
Transient Method ◽  
Vapour Permeability ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Humidity Profiles

An application of a transient method for investigation of water vapour permeability of autoclaved aerated concrete is presented in the paper. Relative humidity profiles along the longitudinal axis of the rod shaped sample are measured using a transient arrangement of a diffusion experiment. Using an inverse analysis of experimentally accessed relative humidity profiles, water vapour permeability of studied material is calculated as function of relative humidity. In the inverse analysis, the Boltzmann-Matano treatment is used as the most straightforward way to the solution of inverse problems to parabolic water vapour diffusion equation.

scholarly journals A semiempirical error estimation technique for PWV derived from atmospheric radiosonde data

2016 ◽  
Vol 9 (9) ◽  
pp. 4759-4781 ◽  
Author(s):  
Julio A. Castro-Almazán ◽  
Gabriel Pérez-Jordán ◽  
Casiana Muñoz-Tuñón
Keyword(s):  
Water Vapour ◽  
Sampling Error ◽  
Precipitable Water ◽  
Semiempirical Method ◽  
The Arctic ◽  
Radiosonde Data ◽  
Optimum Number ◽  
Precipitable Water Vapour ◽  
Water Vapour Content ◽  
Covariance Components

Abstract. A semiempirical method for estimating the error and optimum number of sampled levels in precipitable water vapour (PWV) determinations from atmospheric radiosoundings is proposed. Two terms have been considered: the uncertainties in the measurements and the sampling error. Also, the uncertainty has been separated in the variance and covariance components. The sampling and covariance components have been modelled from an empirical dataset of 205 high-vertical-resolution radiosounding profiles, equipped with Vaisala RS80 and RS92 sondes at four different locations: Güímar (GUI) in Tenerife, at sea level, and the astronomical observatory at Roque de los Muchachos (ORM, 2300 m a.s.l.) on La Palma (both on the Canary Islands, Spain), Lindenberg (LIN) in continental Germany, and Ny-Ålesund (NYA) in the Svalbard Islands, within the Arctic Circle. The balloons at the ORM were launched during intensive and unique site-testing runs carried out in 1990 and 1995, while the data for the other sites were obtained from radiosounding stations operating for a period of 1 year (2013–2014). The PWV values ranged between ∼  0.9 and ∼  41 mm. The method sub-samples the profile for error minimization. The result is the minimum error and the optimum number of levels. The results obtained in the four sites studied showed that the ORM is the driest of the four locations and the one with the fastest vertical decay of PWV. The exponential autocorrelation pressure lags ranged from 175 hPa (ORM) to 500 hPa (LIN). The results show a coherent behaviour with no biases as a function of the profile. The final error is roughly proportional to PWV whereas the optimum number of levels (N0) is the reverse. The value of N0 is less than 400 for 77 % of the profiles and the absolute errors are always <  0.6 mm. The median relative error is 2.0 ±  0.7 % and the 90th percentile P90 = 4.6 %. Therefore, whereas a radiosounding samples at least N0 uniform vertical levels, depending on the water vapour content and distribution of the atmosphere, the error in the PWV estimate is likely to stay below ≈  3 %, even for dry conditions.

scholarly journals Evaluation of upper tropospheric humidity forecasts from ECMWF using AIRS and CALIPSO data

2008 ◽  
Vol 8 (5) ◽  
pp. 17907-17937 ◽  
Author(s):  
N. Lamquin ◽  
K. Gierens ◽  
C. J. Stubenrauch ◽  
R. Chatterjee
Keyword(s):  
Relative Humidity ◽  
Satellite Observation ◽  
Correction Method ◽  
Radiosonde Data ◽  
Atmospheric Infrared Sounder ◽  
Weather Forecasts ◽  
Medium Range ◽  
Upper Tropospheric Humidity ◽  
One Year ◽  
Humidity Profiles

Abstract. An evaluation of the upper tropospheric humidity from the European Centre of Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) is presented. We first make an analysis of the spinup behaviour of ice supersaturation in weather forecasts. It shows that a spinup period of at least 12 h is necessary before using forecast humidity data from the upper troposphere. We compare the forecasted upper tropospheric humidity with coincident relative humidity fields retrieved from the Atmospheric InfraRed Sounder (AIRS) and with cloud vertical profiles from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The analysis is made over one year, from October 2006 to September 2007, and we discuss how relative humidity and cloud features appear both in the IFS and in the observations. In a last part, we investigate the presence of ice supersaturation within low vertical resolution pressure layers by comparing the IFS outputs for high-resolution and low-resolution humidity profiles and by simulating the interpolation of humidity over radiosonde data. A new correction method is proposed and tested with these data.

scholarly journals Water vapour and ozone profiles in the midlatitude upper troposphere

2004 ◽  
Vol 4 (6) ◽  
pp. 8357-8379 ◽  
Author(s):  
G. Vaughan ◽  
C. Cambridge ◽  
L. Dean ◽  
A. W. Phillips
Keyword(s):  
Relative Humidity ◽  
Uniform Distribution ◽  
Water Vapour ◽  
Humidity Sensors ◽  
Upper Troposphere ◽  
Peltier Cooling ◽  
Snow White ◽  
Mirror Reflectivity ◽  
Upper Tropospheric Humidity ◽  
Humidity Profiles

Abstract. We present an investigation of upper tropospheric humidity profiles measured with a standard radiosonde, the Vaisala RS80-A, and a commercial frost-point hygrometer, the Snow White. Modifications to the Snow White, to enable the mirror reflectivity and Peltier cooling current to be monitored during flight, were found to be necessary to determine when the instrument was functioning correctly; a further modification to prevent hydrometeors entering the inlet was also implemented. From 23 combined flights of an ozonesonde, radiosonde and Snow White between September 2001 and July 2002, clear agreement was found between the two humidity sensors, with a mean difference of <2% in relative humidity from 2 to 10 km, and 2.2% between 10 and 13 km. This agreement required a correction to the radiosonde humidity, as described by Miloshevich et al. (2001). Using this result, the dataset of 324 ozonesonde/RS80-A profiles measured from Aberystwyth between 1991 and 2002 was examined to derive statistics for the distribution of water vapour and ozone. Supersaturation with respect to ice was frequently seen at the higher levels – 24% of the time in winter between 8 and 10 km. The fairly uniform distribution of relative humidity persisted to 120% in winter, but decreased rapidly above 100% in summer.

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