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Characterization of the Far Infrared Properties and Radiative Forcing of Antarctic Ice and Water Clouds Exploiting the Spectrometer-LiDAR Synergy. REMOTE SENSING 2020. [DOI: 10.3390/rs12213574] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Optical and microphysical cloud properties are retrieved from measurements acquired in 2013 and 2014 at the Concordia base station in the Antarctic Plateau. Two sensors are used synergistically: a Fourier transform spectroradiometer named REFIR-PAD (Radiation Explorer in Far Infrared-Prototype for Applications and Developments) and a backscattering-depolarization LiDAR. First, in order to identify the cloudy scenes and assess the cloud thermodynamic phase, the REFIR-PAD spectral radiances are ingested by a machine learning algorithm called Cloud Identification and Classification (CIC). For each of the identified cloudy scenes, the nearest (in time) LiDAR backscattering profile is processed by the Polar Threshold (PT) algorithm that allows derivation of the cloud top and bottom heights. Subsequently, using the CIC and PT results as external constraints, the Simultaneous Atmospheric and Clouds Retrieval (SACR) code is applied to the REFIR-PAD spectral radiances. SACR simultaneously retrieves cloud optical depth and effective dimensions and atmospheric vertical profiles of water vapor and temperature. The analysis determines an average effective diameter of 28 μm with an optical depth of 0.76 for the ice clouds. Water clouds are only detected during the austral Summer, and the retrieved properties provide an average droplet diameter of 9 μm and average optical depth equal to four. The estimated retrieval error is about 1% for the ice crystal/droplet size and 2% for the cloud optical depth. The sensitivity of the retrieved parameters to the assumed crystal shape is also assessed. New parametrizations of the optical depth and the longwave downwelling forcing for Antarctic ice and water clouds, as a function of the ice/liquid water path, are presented. The longwave downwelling flux, computed from the top of the atmosphere to the surface, ranges between 70 and 220 W/m2. The estimated cloud longwave forcing at the surface is (31 ± 7) W/m2 and (29 ± 6) W/m2 for ice clouds and (64 ± 12) and (62 ± 11) W/m2 for water clouds, in 2013 and 2014, respectively. The total average cloud forcing for the two years investigated is (46 ± 9) W/m2.
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Radiosonde-Observed Vertical Profiles and Increasing Trends of Temperature and Humidity during 2005–2018 at the South Pole. ATMOSPHERE 2019. [DOI: 10.3390/atmos10070365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The vertical profiles and trends of temperature and humidity at the South Pole up to 10 km above mean sea level (amsl) were investigated by using radiosonde data collected from March 2005 to February 2018. During an average year between 2005 and 2018, the highest (lowest) temperature in the lower troposphere was approximately −25 °C (−60 °C) in December (July) at a height of about 500 m above the surface (at the surface). A temperature inversion layer above the surface was found during the whole year but was weaker during the summer, while the inversion layers at the tropopause (about 8 km amsl) mostly disappeared during spring and winter. General warming trends were found at all heights and months, but in a few heights and months cooling trends still occurred (e.g., in September below 7 km amsl). Nevertheless, seasonal and yearly averaged temperatures all presented warming trends: 1.1, 1.3, 0.6, 1.5 and 1.1 °C/decade at the surface, and 0.7, 1.0, 0.3, 0.3 and 0.6 °C/decade for the layer average from the surface to 10 km amsl, for spring, summer, autumn, winter, and yearly average, respectively. Most of the water vapor was confined in the lowermost 3 km of the atmosphere with a maximum of 0.35 g kg−1 in December at a 200 m height above surface, and the specific humidity had the similar characteristic of annual cycle and inversion layers as the temperature. At heights below 5 km amsl, increasing trends of specific humidity larger than 0.02 g kg−1/decade occurred during summer months, including the late spring and early autumn, and the annual mean showed an increasing trend of about 0.01–0.02 g kg−1/decade. Meanwhile, above 5 km amsl, the trends became small and generally less than 0.02 g kg−1/decade in all the months, and beyond 7 km amsl the specific humidity remained almost invariant due to its small moisture content as compared with lower levels. From the surface to 10 km amsl, the specific humidity averaged trends of 0.0062, 0.019, 0.0013, 0.002 and 0.007 g kg−1/decade for spring, summer, autumn, winter and yearly average, respectively.
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ZHANG WX, LÜ DR, CHANG YL. A Feasibility Study of Cloud Base Height Remote Sensing by Simulating Ground-Based Thermal Infrared Brightness Temperature Measurements. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/cjg2.1041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Wen-Xing ZHANG
- Institute of Atmospheric Physics; Chinese Academy of Sciences; Beijing; 100029; China
| | - Da-Ren LÜ
- Institute of Atmospheric Physics; Chinese Academy of Sciences; Beijing; 100029; China
| | - You-Li CHANG
- College of Resource Environment and Earth Science; Yunnan University; Kunmin; 650091; China
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Adhikari L, Wang Z, Deng M. Seasonal variations of Antarctic clouds observed by CloudSat and CALIPSO satellites. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016719] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Domine F, Gallet JC, Barret M, Houdier S, Voisin D, Douglas TA, Blum JD, Beine HJ, Anastasio C, Bréon FM. The specific surface area and chemical composition of diamond dust near Barrow, Alaska. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jd016162] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Jaross G, Warner J. Use of Antarctica for validating reflected solar radiation measured by satellite sensors. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd008835] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Rathke C, Neshyba S, Shupe MD, Rowe P, Rivers A. Radiative and microphysical properties of Arctic stratus clouds from multiangle downwelling infrared radiances. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jd001545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Carsten Rathke
- Institut für Weltraumwissenschaften; Freie Universität Berlin; Berlin Germany
| | - Steven Neshyba
- Chemistry Department; University of Puget Sound; Tacoma Washington USA
| | - Matthew D. Shupe
- Science and Technology Corporation; NOAA/Environmental Technology Laboratory; Boulder Colorado USA
| | - Penny Rowe
- Department of Chemistry; University of Washington; Seattle Washington USA
| | - Aaron Rivers
- Cooperative Institute for Research in Environmental Sciences; University of Colorado; Boulder Colorado USA
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Mahesh A, Walden VP, Warren SG. Ground-Based Infrared Remote Sensing of Cloud Properties over the Antarctic Plateau. Part II: Cloud Optical Depths and Particle Sizes. ACTA ACUST UNITED AC 2001. [DOI: 10.1175/1520-0450(2001)040<1279:gbirso>2.0.co;2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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