Ground-based Atmospheric Emitted Radiance Interferometer Research Articles

Information Content of a Synergy of Ground-Based and Space-Based Infrared Sounders. Part I: Clear-Sky Environments

Abstract Profiles of atmospheric temperature and water vapor from remotely sensed platforms provide critical observations within the temporal and spatial gaps of the radiosonde network. The 2017 National Academies of Science Decadal Survey highlighted that observations of the planetary boundary layer (PBL) from the current space-based observing system are not of the necessary accuracy or resolution for monitoring and predicting high-impact weather phenomena. One possible solution to improving observations of the PBL is supplementing the existing space-based observing system with a network of ground-based profilers. A synthetic information content study is developed utilizing profiles from the Atmospheric Radiation Measurement (ARM) program sites at the Southern Great Plains (SGP), east North Atlantic (ENA), and North Slope of Alaska (NSA) to assess the benefits, in terms of degrees of freedom (DOF), vertical resolution, and uncertainties, of a synergy between the ground-based Atmospheric Emitted Radiance Interferometer (AERI) with space-based hyperspectral infrared (IR) sounders. A combination of AERI with any of the three polar-orbiting IR sounders: the Atmospheric Infrared Sounder (AIRS), the Cross-track Infrared Sounder (CrIS), or the Infrared Atmospheric Sounding Interferometer (IASI), results in a DOF increase of 30%–40% in the surface-to-700-hPa layer compared to the space-based instrument alone. Introducing AERI measurements to the observing system also results in significant improvements to vertical resolution and uncertainties in the bottom 1000 m of the atmosphere compared to CrIS measurements alone. A synergy of CrIS and AERI exceeds the 1-km-vertical-resolution goal set by the Decadal Survey in the lowest 1000 m.

계절별 AERI 기준 스펙트럼 적용을 통한 구름에 영향을 받은 스펙트럼 자료 제거방법 개선

Abstract : The Atmospheric Emitted Radiance Interferometer (AERI) which is the Fourier TransformInfraRed (FTIR) spectrometer has been operated by the National Institute of Meteorological Research(NIMR) in Anmyeon island, South Korea since June 2010. The ground-based AERI with similar hyper-spectral infrared sensor to satellite could be an alternative way to validate satellite-based remote sensing.In this regard, the NIMR has focused on the improvement of Cloud data Filtering Method (CFM) whichemployed only one reference spectrum of clear sky in winter season. This study suggests Seasonal-Clouddata Filtering Method (S-CFM) which applied seasonal AERI reference spectra. For the comparison ofapplied S-CFM and CFM, the methane retrievals (surface volume mixing ratio) from AERI spectra areused. The quality of AERI methane retrieval applied S-CFM was significantly more improved than thatof CFM. The positive result of S-CFM is similar pattern with the seasonal variation of methane fromground-based in-situ measurement, even if the summer season’s methane is retrieved over-estimation. Inaddition, the comparison of vertical total column of methane from AERI and GOSAT shows good resultexcept for the summer season.Key Words : AERI, Cloud Filtering, FTIR, Infrared, Remote sensing, Satellite, GOSAT, Methaneretrieval요약 :

AERI 스펙트럼 분석을 통한 구름에 영향을 받은 스펙트럼 자료 제거 방법 개선

Abstract : The National Institute of Meteorological Research (NIMR) has operated the FourierTransform InfraRed (FTIR) spectrometer which is the Atmospheric Emitted Radiance Interferometer(AERI) in Anmyeon island, Korea since June 2010. The ground-based AERI with similar hyper-spectralinfrared sensor to satellite could be an alternative way to validate satellite-based remote sensing. In thisregard, the NIMR has focused on the improvement of retrieval quality from the AERI, particularly cloud-data filtering method. The AERI spectrum which is measured on a typical clear day is selected referencespectrum and we used region of atmospheric window. We performed test of threshold in order to selectvalid threshold. We retrieved methane using new method which is used reference spectrum, and the othermethod which is used KLAPS cloud cover information, each retrieved methane was compared with thatof ground-based in-situ measurements. The quality of AERI methane retrievals of new method wassignificantly more improved than method of used KLAPS. In addition, the comparison of vertical totalcolumn of methane from AERI and GOSAT shows good result.Key Words : AERI, Cloud Filtering, FTIR, Infrared, Remote sensing, Satellite.요약 :

Retrievals of atmospheric boundary layer temperature and moisture profiles by using Atmospheric Emitted Radiance Interferometer (AERI) measurements in Shouxian

The ground-based Atmospheric Emitted Radiance Interferometer (AERI) was deployed in Shouxian, China in 2008 to measure down-welling infrared radiances with high resolution. Based on AERI observations, we propose a new method for retrieving vertical temperature and water vapor profiles in the planetary boundary layer (PBL). The method exclusively uses NCEP-2, a global reanalysis data as a first-guess profile in an iterative recursive algorithm. The PBL profiles of temperature and moisture under clear sky conditions in Shouxian have been retrieved using this new method. Compared with coincident radiosonde measurements, we find that AERI is able to obtain more accurate temperature and water vapor profiles in the PBL. The retrieval results with high temporal resolution can be used to monitor the PBL stability and evolution.

A new method for retrieving equivalent cloud base height and equivalent emissivity by using the ground-based Atmospheric Emitted Radiance Interferometer (AERI)

In the paper, we propose a new method of identifying the clear sky based on the Atmospheric Emitted Radiance Interferometer (AERI). Using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AFM) dataset in Shouxian in 2008, we simulate the downwelling radiances on the surface in the 8–12 μm window region using Line-By-Line Radiative Transfer Model (LBLRTM), and compare the results with the AERI radiances. The differences larger (smaller) than 3 mW (cm2 sr cm−1)−1 suggest a cloudy (clear) sky. Meanwhile, we develop the new algorithms for retrieving the zenith equivalent cloud base height (CBHe) and the equivalent emissivity (ɛe), respectively. The retrieval methods are described as follows. (1) An infinitely thin and isothermal blackbody cloud is simulated by the LBLRTM. The cloud base height (H) is adjusted iteratively to satisfy the situation that the contribution of the blackbody to the downwelling radiance is equal to that of realistic cloud. The final H is considered as CBHe. The retrieval results indicate that the differences between the CBHe and observational cloud base height (CBH) are much smaller for thick low cloud, and increase with the increasing CBH. (2) An infinitely thin and isothermal gray body cloud is simulated by the LBLRTM, with the CBH specified as the observed value. The cloud base emissivity (ɛc) is adjusted iteratively until the contribution of the gray body to the downwelling radiance is the same as that of realistic cloud. The corresponding ɛc is ɛe. The average ɛe for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respectively. It decreases with the increasing CBH. The retrieval results will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model.

Cloud Base Height and Effective Cloud Emissivity Retrieval with Ground-Based Infrared Interferometer

AbstractBased on ground-based Atmospheric Emitted Radiance Interferometer (AERI) observations in Shouxian, Anhui province, China, the authors retrieve the cloud base height (CBH) and effective cloud emissivity by using the minimum root-mean-square difference method. This method was originally developed for satellite remote sensing. The high-temporal-resolution retrieval results can depict the trivial variations of the zenith clouds continuously. The retrieval results are evaluated by comparing them with observations by the cloud radar. The comparison shows that the retrieval bias is smaller for the middle and low cloud, especially for the opaque cloud. When two layers of clouds exist, the retrieval results reflect the weighting radiative contribution of the multi-layer cloud. The retrieval accuracy is affected by uncertainties of the AERI radiances and sounding profiles, in which the role of uncertainty in the temperature profile is dominant.

Near-Continuous Profiling of Temperature, Moisture, and Atmospheric Stability Using the Atmospheric Emitted Radiance Interferometer (AERI)

Abstract The Department of Energy Atmospheric Radiation Measurement Program (ARM) has funded the development and installation of five ground-based atmospheric emitted radiance interferometer (AERI) systems at the Southern Great Plains (SGP) site. The purpose of this paper is to provide an overview of the AERI instrument, improvement of the AERI temperature and moisture retrieval technique, new profiling utility, and validation of high-temporal-resolution AERI-derived stability indices important for convective nowcasting. AERI systems have been built at the University of Wisconsin—Madison, Madison, Wisconsin, and deployed in the Oklahoma–Kansas area collocated with National Oceanic and Atmospheric Administration 404-MHz wind profilers at Lamont, Vici, Purcell, and Morris, Oklahoma, and Hillsboro, Kansas. The AERI systems produce absolutely calibrated atmospheric infrared emitted radiances at one-wavenumber resolution from 3 to 20 μm at less than 10-min temporal resolution. The instruments are robust, are a...

Retrieval of atmospheric-temperature and water-vapor profiles by use of combined satellite and ground-based infrared spectral-radiance measurements.

A nonlinear sounding retrieval algorithm is used to produce vertical-temperature and water-vapor profiles from coincident observations taken by the airborne High-resolution Interferometer Sounder (HIS) and the ground-based Atmospheric Emitted Radiance Interferometer (AERI) during the SUbsonic Contrails and Clouds Effects Special Study (SUCCESS). Also, clear sky Geostationary Operational Environmental Satellite (GOES) and AERI radiance measurements, achieved on a daily real-time basis at the Department of Energy's Oklahoma CART (Cloud and Radiation Testbed) site, are used to demonstrate the current profiling capability by use of simultaneous geostationary satellite and ground-based remote sensing observations under clear-sky conditions. The discrepancy principle, a method to find the proper smoothing parameters from the minimum value between the normalized spectral residual norm and the a priori upper bound, is used to demonstrate the feasibility and effectiveness of on-line simultaneous tuning of the multiple weighting and smoothing parameters from the combined satellite/airborne and ground-based measurements for the temperature and water-vapor retrieval in this nonlinear-retrieval process. An objective method to determine the degrees of freedom (d.f.) of the observation signal is derived. The d.f. of the radiance signal for the combined GOES and AERI measurements is larger than that for either instrument alone; while the d.f. of the observation signal for the combined GOES and AERI measurements is larger than that for either instrument alone and of the combined GOES and AERI measurements. The use of simultaneous clear-sky AERI and GOES data now provides improved vertical temperature and moisture soundings on an hourly basis for use in the Atmospheric Radiation Measurement program [J. Appl. Meteorol. 37, 875 (1998)].

Monitoring High-Temporal-Resolution Convective Stability Indices Using the Ground-Based Atmospheric Emitted Radiance Interferometer (AERI) during the 3 May 1999 Oklahoma–Kansas Tornado Outbreak

Abstract The Department of Energy Atmospheric Radiation Measurement Program has funded the development and installation of five atmospheric emitted radiance interferometer (AERI) systems around the Southern Great Plains Cloud and Radiation Test Bed located in Oklahoma and Kansas. The AERI instruments measure atmospheric emitted radiance to within 1% ambient radiance at 1 cm–1 spectral resolution from 520 to 3000 cm–1 (3–20 μm) at 10-min temporal resolution. This high-spectral-resolution radiance information is inverted through a form of the infrared radiative transfer equation to produce temperature and water vapor profiles within the planetary boundary layer (to 3 km), effectively mapping the thermodynamic state of the lower troposphere. Taking advantage of the 10-min resolution of the AERI thermodynamic profiles, the convective destabilization during the 3 May 1999 Oklahoma–Kansas tornado outbreak is analyzed. Tropospheric changes involving the rapid (on the order of 1–2 h) dissipation of a capping temp...

Tropospheric carbon monoxide column density retrieval during Pre-launch MOPITT Validation exercise

The tropospheric carbon monoxide (CO) column density over the United States Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility near Lamont, Oklahoma (latitude 36°37′N, longitude 97°30′W) during the Pre-launch MOPITT Validation Exercise (Pre-MOVE) is retrieved from infrared spectra obtained by the ground-based Atmospheric Emitted Radiance Interferometer (AERI). This paper reports the first tropospheric CO time series retrieved from an AERI. With spectra measured every 8 min, CO retrieved from AERI spectra has a much higher temporal resolution than from any other ground-based instrument measuring atmospheric emission. The retrieved CO column density time series is examined using local meteorological data. Synoptic atmospheric conditions are found to have a controlling effect on tropospheric CO. During 2–4 March, 1998, a southerly to easterly surface wind brought an airmass with higher CO column density over the SGP Central Facility (SGPCF), whereas northerly and/or westerly surface winds tended to reduce the CO column density.

Meteorological Applications of Temperature and Water Vapor Retrievals from the Ground-Based Atmospheric Emitted Radiance Interferometer (AERI)

Abstract The Atmospheric Emitted Radiance Interferometer (AERI) is a well-calibrated ground-based instrument that measures high-resolution atmospheric emitted radiances from the atmosphere. The spectral resolution of the instrument is better than one wavenumber between 3 and 18 μm within the infrared spectrum. The AERI instrument detects vertical and temporal changes of temperature and water vapor in the planetary boundary layer. Excellent agreement between radiosonde and AERI retrievals for a 6-month sample of coincident profiles is presented in this paper. In addition, a statistical seasonal analysis of retrieval and radiosonde differences is discussed. High temporal and moderate vertical resolution in the lowest 3 km of the atmosphere allows meteorologically important mesoscale features to be detected. AERI participation in the Department of Energy Atmospheric Radiation Measurement program at the Southern Great Plains Cloud and Radiation Testbed (SGP CART) has allowed development of a robust operationa...