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

2009 ◽  
Vol 9 (5) ◽  
pp. 1779-1793 ◽  
Author(s):  
N. Lamquin ◽  
K. Gierens ◽  
C. J. Stubenrauch ◽  
R. Chatterjee
Keyword(s):  
Relative Humidity ◽  
Satellite Observation ◽  
Correction Method ◽  
Radiosonde Data ◽  
Vertical Resolution ◽  
Atmospheric Infrared Sounder ◽  
Weather Forecasts ◽  
Clear Sky ◽  
Upper Tropospheric Humidity ◽  
One Year

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. The comparison with AIRS is made difficult because of the vertical resolution of the sounder and the impossibility to retrieve humidity for high cloudiness. Clear sky relative humidities show a rather good correlation whereas cloudy situations reflect more the effect of a dry bias for AIRS increasing with the relative humidity. The comparison with CALIPSO shows that the IFS predicts high relative humidity where CALIPSO finds high clouds, which supports the good quality of the ECMWF upper tropospheric cloud forecast. 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 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 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 Performance of the Vaisala RS80A/H and RS90 Humicap Sensors and the Meteolabor “Snow White” Chilled-Mirror Hygrometer in Paramaribo, Suriname

2006 ◽  
Vol 23 (11) ◽  
pp. 1506-1518 ◽  
Author(s):  
Gé Verver ◽  
Masatomo Fujiwara ◽  
Pier Dolmans ◽  
Cor Becker ◽  
Paul Fortuin ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Time Lag ◽  
Lower Troposphere ◽  
Upper Troposphere ◽  
Weather Forecasts ◽  
Snow White ◽  
Study Results ◽  
The Tropics ◽  
Humidity Profiles ◽  
Dry Bias

Abstract In climate research there is a strong need for accurate observations of water vapor in the upper atmosphere. Radiosoundings provide relative humidity profiles but the accuracy of many routine instruments is notoriously inadequate in the cold upper troposphere. In this study results from a soundings program executed in Paramaribo, Suriname (5.8°N, 55.2°W), are presented. The aim of this program was to compare the performance of different humidity sensors in the upper troposphere in the Tropics and to test different bias corrections suggested in the literature. The payload of each sounding consisted of a chilled-mirror “Snow White” sensor from Meteolabor AG, which was used as a reference, and two additional sensors from Vaisala, that is, either the RS80A, the RS80H, or the RS90. In total 37 separate soundings were made. For the RS80A a clear, dry bias of between −4% and −8% RH is found in the lower troposphere compared to the Snow White observation, confirming the findings in previous studies. A mean dry bias was found in the upper troposphere, which could be effectively corrected. The RS80H sensor shows a significant wet bias of 2%–5% in RH in the middle and upper troposphere, which has not been reported before. Comparing observations with RS80H sensors of different ages gives no indication of sensor aging or sensor contamination. It is therefore concluded that the plastic cover introduced by Vaisala to avoid sensor contamination is effective. Finally, the RS90 sensor yields a small but significant wet bias of 2%–3% below 7-km altitude. The time-lag error correction from Miloshevich et al. was applied to the Vaisala data, which resulted in an increased variability in the relative humidity profile above 9- (RS80A), 8- (RS80H), and 11-km (RS90) altitude, respectively, which is in better agreement with the Snow White data. The averaged Snow White profile is compared with the average profiles of relative humidity from the European Centre for Medium-Range Weather Forecasts (ECMWF). No significant bias is found in either the analyses or the forecasts. The correlation coefficient for the Snow White and ECMWF data between 200 and 800 hPa was 0.66 for the 36-h forecast and 0.77 for the analysis.

scholarly journals Global characteristics of the westward-propagating quasi-16-day wave with zonal wavenumber 1 and the connection with the 2012/2013 SSW revealed by ERA-Interim

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Wei Li ◽  
Chunming Huang ◽  
Shaodong Zhang
Keyword(s):  
Baroclinic Instability ◽  
Polar Vortex ◽  
Meridional Wind ◽  
Local Source ◽  
High Latitudes ◽  
Stratospheric Sudden Warming ◽  
Weather Forecasts ◽  
Zonal Wavenumber ◽  
Medium Range ◽  
One Year

AbstractWe analyze global characteristics of the westward-propagating quasi-16-day wave (Q16DW) with zonal wavenumber 1 (W1) in the troposphere and stratosphere using zonal wind, meridional wind, vertical velocity, temperature, geopotential, and potential vorticity data from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis during one year from December 2012 to November 2013. The amplitudes of the W1 Q16DW are larger in the stratosphere than in the troposphere, and remarkable amplitudes are found at middle and high latitudes in the Northern Hemisphere (NH). More detailed analyses on the temporal variation in the W1 Q16DW show that this wave is significantly enhanced during the 2012/2013 Stratospheric Sudden Warming (SSW) event, and the strong wave most likely provides additional forcing on the splitting of the displaced polar vortex. Analysis of the Eliassen–Palm flux (EP flux) and its divergence of the interaction between W1 Q16DW and quasi-stationary planetary waves with wavenumber 1 during the 2012/2013 SSW event reveals that it causes an upward heat flux and exerts a westward acceleration on the background winds, indicating that this interaction plays an important role in the eastward stratospheric jet reversal. Moreover, the wave is amplified in the occurrence region of barotropic and/or baroclinic instability, suggesting a local source of the growing W1 Q16DW during this SSW event.

scholarly journals NASA A-Train and Terra observations of the 2010 Russian wildfires

2011 ◽  
Vol 11 (17) ◽  
pp. 9287-9301 ◽  
Author(s):  
J. C. Witte ◽  
A. R. Douglass ◽  
A. da Silva ◽  
O. Torres ◽  
R. Levy ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Heat Wave ◽  
High Surface ◽  
Longwave Radiation ◽  
Cyclonic Circulation ◽  
Radiosonde Data ◽  
Ozone Monitoring Instrument ◽  
Atmospheric Infrared Sounder ◽  
Back Trajectories ◽  
Fire Activity

Abstract. Wildfires raged throughout western Russia and parts of Eastern Europe during a persistent heat wave in the summer of 2010. Anomalously high surface temperatures (35–41 °C) and low relative humidity (9–25 %) from mid-June to mid-August 2010 shown by analysis of radiosonde data from multiple sites in western Russia were ideal conditions for the wildfires to thrive. Measurements of outgoing longwave radiation (OLR) from the Atmospheric Infrared Sounder (AIRS) over western Russian indicate persistent subsidence during the heat wave. Daily three-day back-trajectories initiated over Moscow reveal a persistent anti-cyclonic circulation for 18 days in August, coincident with the most intense period of fire activity observed by Moderate Resolution Imaging Spectroradiometer (MODIS). This unfortunate meteorological coincidence allowed transport of polluted air from the region of intense fires to Moscow and the surrounding area. We demonstrate that the 2010 Russian wildfires are unique in the record of observations obtained by remote-sensing instruments on-board NASA satellites: Aura and Aqua (part of the A-Train Constellation) and Terra. Analysis of the distribution of MODIS fire products and aerosol optical thickness (AOT), UV aerosol index (AI) and single-scattering albedo (SSA) from Aura's Ozone Monitoring Instrument (OMI), and total column carbon monoxide (CO) from Aqua's Atmospheric Infrared Sounder (AIRS) show that the region in the center of western Russia surrounding Moscow (52°–58° N, 33°–43° E) is most severely impacted by wildfire emissions. Over this area, AIRS CO, OMI AI, and MODIS AOT are significantly enhanced relative to the historical satellite record during the first 18 days in August when the anti-cyclonic circulation persisted. By mid-August, the anti-cyclonic circulation was replaced with westerly transport over Moscow and vicinity. The heat wave ended as anomalies of surface temperature and relative humidity, and OLR disappeared. After 18 August the fire activity greatly diminished over western Russia and levels of the satellite smoke tracers returned to values typical of previous years.

Multivariate Minimum Residual Method for Cloud Retrieval. Part I: Theoretical Aspects and Simulated Observation Experiments

2014 ◽  
Vol 142 (12) ◽  
pp. 4383-4398 ◽  
Author(s):  
Thomas Auligné
Keyword(s):  
Three Dimensional ◽  
New Method ◽  
Cloud Detection ◽  
Atmospheric Infrared Sounder ◽  
Detection Scheme ◽  
Weather Forecasts ◽  
Independent Information ◽  
Medium Range ◽  
Minimum Residual ◽  
Infrared Radiances

Abstract A new method is presented for cloud detection and the retrieval of three-dimensional cloud fraction from satellite infrared radiances. This method, called multivariate minimum residual (MMR), is inspired by the minimum residual technique by Eyre and Menzel and is especially suitable for exploiting the large number of channels from hyperspectral infrared sounders. Its accuracy is studied in a theoretical framework where the observations and the numerical model are supposed perfect. Of particular interest is the number of independent information that can be found on the cloud according to the number of channels used. The technical implementation of the method is also briefly discussed. The MMR scheme is validated with the Atmospheric Infrared Sounder (AIRS) instrument using simulated observations. This new method is compared with the cloud-detection scheme from McNally and Watts that is operational at the European Centre for Medium-Range Weather Forecasts (ECMWF) and considered to be the state of the art in cloud detection for hyperspectral infrared sounders.

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