TY - JOUR
T1 - Retrieval of cloud properties from spectral zenith radiances observed by sky radiometers
AU - Khatri, Pradeep
AU - Iwabuchi, Hironobu
AU - Hayasaka, Tadahiro
AU - Irie, Hitoshi
AU - Takamura, Tamio
AU - Yamazaki, Akihiro
AU - Damiani, Alessandro
AU - Letu, Husi
AU - Kai, Qin
N1 - Funding Information:
Aerospace Exploration Agency (PI no. ER2GCF211, contract no. 19RT000370), the Japan Society for the Promotion of Science (JSPS) (grant no. 17K05650), and the CREST/JST (grant no. JP-MJCR15K4).
Funding Information:
Acknowledgements. This research is supported by the 2nd Research Announcement on the Earth Observations of the Japan Aerospace Exploration Agency (JAXA) (PI no. ER2GCF211, contract no. 19RT000370), a Grant-in-Aid for Scientific Research (C) (no. 17K05650) from the Japan Society for the Promotion of Science (JSPS), the “virtual laboratory for diagnosing the earth’s climate system” program of MEXT, Japan, and the CREST/JST research fund (grant no. JPMJCR15K4).
Funding Information:
Financial support. This research has been supported by the Japan
Publisher Copyright:
© 2019 Author(s).
PY - 2019/11/21
Y1 - 2019/11/21
N2 - An optimal estimation algorithm to retrieve the cloud optical depth (COD) and cloud particle effective radius (CER) from spectral zenith radiances observed by narrow field-of-view (FOV) ground-based sky radiometers was developed. To further address the filter degradation problem while analyzing long-term observation data, an on-site calibration procedure is proposed, which has good accuracy compared with the standard calibration transfer method. An error evaluation study conducted by assuming errors in observed transmittances and ancillary data for water vapor concentration and surface albedo suggests that the errors in input data affect retrieved CER more than COD. Except for some narrow domains that fall within a COD of < 15, the retrieval errors are small for both COD and CER. The retrieved cloud properties reproduce the broadband radiances observed by a narrow FOV radiometer more precisely than broadband irradiances observed by a wide-FOV pyranometer, justifying the quality of the retrieved product (at least of COD) and indicating the important effect of the instrument FOV in cloud remote sensing. Furthermore, CODs (CERs) from sky radiometer and satellite observations show good (poor) agreement.
AB - An optimal estimation algorithm to retrieve the cloud optical depth (COD) and cloud particle effective radius (CER) from spectral zenith radiances observed by narrow field-of-view (FOV) ground-based sky radiometers was developed. To further address the filter degradation problem while analyzing long-term observation data, an on-site calibration procedure is proposed, which has good accuracy compared with the standard calibration transfer method. An error evaluation study conducted by assuming errors in observed transmittances and ancillary data for water vapor concentration and surface albedo suggests that the errors in input data affect retrieved CER more than COD. Except for some narrow domains that fall within a COD of < 15, the retrieval errors are small for both COD and CER. The retrieved cloud properties reproduce the broadband radiances observed by a narrow FOV radiometer more precisely than broadband irradiances observed by a wide-FOV pyranometer, justifying the quality of the retrieved product (at least of COD) and indicating the important effect of the instrument FOV in cloud remote sensing. Furthermore, CODs (CERs) from sky radiometer and satellite observations show good (poor) agreement.
UR - http://www.scopus.com/inward/record.url?scp=85075689002&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85075689002&partnerID=8YFLogxK
U2 - 10.5194/amt-12-6037-2019
DO - 10.5194/amt-12-6037-2019
M3 - Article
AN - SCOPUS:85075689002
VL - 12
SP - 6037
EP - 6047
JO - Atmospheric Measurement Techniques
JF - Atmospheric Measurement Techniques
SN - 1867-1381
IS - 11
ER -