scholarly journals Why Scanning Instruments Are a Necessity for Constraining Temperature and Humidity Fields in the Lower Atmosphere

2014 ◽  
Vol 31 (11) ◽  
pp. 2462-2481 ◽  
Author(s):  
David Themens ◽  
Frédéric Fabry
Keyword(s):  
Water Vapor ◽  
Microwave Radiometer ◽  
Three Dimensional ◽  
Optimal Estimation ◽  
Lower Atmosphere ◽  
Temperature Fields ◽  
Vertical Profiling ◽  
Thermodynamic Variables ◽  
Free Environment ◽  
Measurement Strategies

AbstractThe ability of different ground-based measurement strategies for constraining thermodynamic variables in the troposphere, particularly at the mesoscale, is investigated. First, a preliminary assessment of the capability of pure-vertical sounders for constraining temperature and water vapor fields in clear-sky conditions to current accuracy requirements is presented. Using analyses over one month from the Rapid Refresh model as input to an optimal estimation technique, it is shown that the horizontal density of a network of nonexisting, ideal vertical profiling instruments must be greater than 30 km in order to achieve accuracies of 0.5 g kg−1 for water vapor and 0.5 K for temperature. Then, an assessment of a scanning microwave radiometer’s capability for retrieving water vapor and temperature fields in a cloud-free environment over two- and three-dimensional mesoscale domains is also presented. The information content of an elevation and azimuthal scanning microwave radiometer is assessed using the same optimal estimation framework. Even though, in any specific pointing direction, the scanning radiometer does not provide much information, it is capable of providing considerably more constraints on thermodynamic fields, particularly water vapor, than a near-perfect vertical sounder. These constraints on water vapor are largely located within 80 km of the radiometer and between 1000- and 7000-m altitude, while temperature constraints are limited to within 35 km of the instrument at altitudes between the ground and 1500 m. The findings suggest that measurements from scanning radiometers will be needed to properly constrain the temperature and especially moisture fields to accuracies needed for mesoscale forecasting.

scholarly journals Potential of Dual-Frequency Radar and Microwave Radiometer Synergy for Water Vapor Profiling in the Cloudy Trade Wind Environment

2020 ◽  
Vol 37 (11) ◽  
pp. 1973-1986
Author(s):  
Sabrina Schnitt ◽  
Ulrich Löhnert ◽  
René Preusker
Keyword(s):  
Water Vapor ◽  
Information Content ◽  
Degrees Of Freedom ◽  
Microwave Radiometer ◽  
Optimal Estimation ◽  
Cloud Layer ◽  
Trade Wind ◽  
Dual Frequency ◽  
Shallow Convection ◽  
Brightness Temperatures

AbstractHigh-resolution boundary layer water vapor profile observations are essential for understanding the interplay between shallow convection, cloudiness, and climate in the trade wind atmosphere. As current observation techniques can be limited by low spatial or temporal resolution, the synergistic benefit of combining ground-based microwave radiometer (MWR) and dual-frequency radar is investigated by analyzing the retrieval information content and uncertainty. Synthetic MWR brightness temperatures, as well as simulated dual-wavelength ratios of two radar frequencies are generated for a combination of Ka and W band (KaW), as well as differential absorption radar (DAR) G-band frequencies (167 and 174.8 GHz, G2). The synergy analysis is based on an optimal estimation scheme by varying the configuration of the observation vector. Combining MWR and KaW only marginally increases the retrieval information content. The synergy of MWR with G2 radar is more beneficial due to increasing degrees of freedom (4.5), decreasing retrieval errors, and a more realistic retrieved profile within the cloud layer. The information and profile below and within the cloud is driven by the radar observations, whereas the synergistic benefit is largest above the cloud layer, where information content is enhanced compared to an MWR-only or DAR-only setup. For full synergistic benefits, however, G-band radar sensitivities need to allow full-cloud profiling; in this case, the results suggest that a combined retrieval of MWR and G-band DAR can help close the observational gap of current techniques.

scholarly journals The Impact of Aerosols on Satellite Radiance Data Assimilation Using NCEP Global Data Assimilation System

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 432
Author(s):  
Shih-Wei Wei ◽  
Cheng-Hsuan (Sarah) Lu ◽  
Quanhua Liu ◽  
Andrew Collard ◽  
Tong Zhu ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Lower Atmosphere ◽  
Temperature Fields ◽  
Infrared Sensors ◽  
Research Attention ◽  
Brightness Temperatures ◽  
Thermal Window ◽  
Global Data Assimilation System ◽  
The Impact

Aerosol radiative effects have been studied extensively by climate and weather research communities. However, aerosol impacts on radiance in the context of data assimilation (DA) have received little research attention. In this study, we investigated the aerosol impacts on the assimilation of satellite radiances by incorporating time-varying three-dimensional aerosol distributions into the radiance observation operator. A series of DA experiments was conducted for August 2017. We assessed the aerosol impacts on the simulated brightness temperatures (BTs), bias correction and quality control (QC) algorithms for the assimilated infrared sensors, and analyzed temperature fields. We found that taking the aerosols into account reduces simulated BT in thermal window channels (8 to 13μm) by up to 4 K over dust-dominant regions. The cooler simulated BTs result in more positive first-guess departures, produce more negative biases, and alter the QC checks about 20%/40% of total/assimilated observations at the wavelength of 10.39μm. As a result, assimilating aerosol-affected BTs produces a warmer analyzed lower atmosphere and sea surface temperature which have better agreement with measurements over the trans-Atlantic region.

MicroPulse DIAL (MPD) ground-based network for Thermodynamic Profiling in the Lower Troposphere

2020 ◽  
Author(s):  
Scott Spuler ◽  
Robert Stillwell ◽  
Matt Hayman ◽  
Tammy Weckwerth ◽  
Kevin Repasky
Keyword(s):  
Water Vapor ◽  
Weather Forecasting ◽  
Low Cost ◽  
Lower Troposphere ◽  
Atmospheric Temperature ◽  
Lower Atmosphere ◽  
High Spectral Resolution ◽  
Montana State University ◽  
Aerosol Scattering ◽  
Thermodynamic Variables

<p>The National Center for Atmospheric Research and Montana State University have developed a 5-unit ground-based test network of MicroPulse Differential Absorption Lidar (MPD) instruments to continuously measure high-vertical-resolution water vapor profiles in the lower atmosphere. These diode-laser-based instruments are accurate, low-cost, operate unattended, do not require external calibration, and eye-safe – all key features to enable larger 'national-scale' networks needed to characterize atmospheric moisture variability, which influences important processes related to weather and climate.  Enhancements to the water vapor MPD architecture have been recently developed that enable quantitative aerosol measurements and atmospheric temperature profiling by simultaneously measuring O2 absorption and aerosol backscatter ratio. This combination of measurements allows for the first DIAL measurements of atmospheric temperature with useful accuracy. The MPD has been demonstrated to provide continuous, range-resolved measurements of atmospheric thermodynamic variables, water vapor and temperature, and quantitative measurements of aerosol scattering from a high spectral resolution (HSRL) channel.  Thus, a network of these instruments shows promise to provide atmospheric profiling capabilities needed by both the climate and weather forecasting research communities.</p>

scholarly journals New Gridded Product for the Total Columnar Atmospheric Water Vapor over Ocean Surface Constructed from Microwave Radiometer Satellite Data

2021 ◽  
Vol 13 (12) ◽  
pp. 2402
Author(s):  
Weifu Sun ◽  
Jin Wang ◽  
Yuheng Li ◽  
Junmin Meng ◽  
Yujia Zhao ◽  
...  
Keyword(s):  
Water Vapor ◽  
Microwave Radiometer ◽  
Atmospheric Water Vapor ◽  
Global Ocean ◽  
Optimal Interpolation ◽  
Fusion Product ◽  
Mean Deviation ◽  
Atmospheric Water ◽  
Absolute Deviation ◽  
Better Than

Based on the optimal interpolation (OI) algorithm, a daily fusion product of high-resolution global ocean columnar atmospheric water vapor with a resolution of 0.25° was generated in this study from multisource remote sensing observations. The product covers the period from 2003 to 2018, and the data represent a fusion of microwave radiometer observations, including those from the Special Sensor Microwave Imager Sounder (SSMIS), WindSat, Advanced Microwave Scanning Radiometer for Earth Observing System sensor (AMSR-E), Advanced Microwave Scanning Radiometer 2 (AMSR2), and HY-2A microwave radiometer (MR). The accuracy of this water vapor fusion product was validated using radiosonde water vapor observations. The comparative results show that the overall mean deviation (Bias) is smaller than 0.6 mm; the root mean square error (RMSE) and standard deviation (SD) are better than 3 mm, and the mean absolute deviation (MAD) and correlation coefficient (R) are better than 2 mm and 0.98, respectively.

scholarly journals A Method of Estimating Three-Dimensional Wind Velocity and Conversion Rate of Water Vapor Using Information on Echo from Three-Dimensionally Scanning Radar

1992 ◽  
Vol 36 ◽  
pp. 483-488
Author(s):  
Eiichi Nakakita ◽  
Minoru Tanaka ◽  
Michiharu Shiiba ◽  
Shuichi Ikebuchi ◽  
Takuma Takasao
Keyword(s):  
Water Vapor ◽  
Wind Velocity ◽  
Conversion Rate ◽  
Three Dimensional

scholarly journals Water vapor transport in the lower mesosphere of the subtropics: a trajectory analysis

2008 ◽  
Vol 8 (23) ◽  
pp. 7273-7280 ◽  
Author(s):  
T. Flury ◽  
S. C. Müller ◽  
K. Hocke ◽  
N. Kämpfer
Keyword(s):  
Water Vapor ◽  
Trajectory Analysis ◽  
Microwave Radiometer ◽  
Rotational Transition ◽  
Transport Processes ◽  
Water Vapor Transport ◽  
Transition Line ◽  
Wind Fields ◽  
Large Variability ◽  
Northern India

Abstract. The Institute of Applied Physics operates an airborne microwave radiometer AMSOS that measures the rotational transition line of water vapor at 183.3 GHz. Water vapor profiles are retrieved for the altitude range from 15 to 75 km along the flight track. We report on a water vapor enhancement in the lower mesosphere above India and the Arabian Sea. The measurements took place on our flight from Switzerland to Australia and back in November 2005 conducted during EC- project SCOUT-O3. We find an enhancement of up to 25% in the lower mesospheric H2O volume mixing ratio measured on the return flight one week after the outward flight. The origin of the air is traced back by means of a trajectory model in the lower mesosphere and wind fields from ECMWF. During the outward flight the air came from the Atlantic Ocean around 25 N and 40 W. On the return flight the air came from northern India and Nepal around 25 N and 90 E. Mesospheric H2O measurements from Aura/MLS confirm the transport processes of H2O derived by trajectory analysis of the AMSOS data. Thus the large variability of H2O VMR during our flight is explained by a change of the winds in the lower mesosphere. This study shows that trajectory analysis can be applied in the mesosphere and is a powerful tool to understand the large variability in mesospheric H2O.

Sign in / Sign up

Export Citation Format

Share Document