scholarly journals The New Potential of Deep Convective Clouds as a Calibration Target for a Geostationary UV/VIS Hyperspectral Spectrometer

2020 ◽  
Vol 12 (3) ◽  
pp. 446 ◽  
Author(s):  
Yeeun Lee ◽  
Myoung-Hwan Ahn ◽  
Mina Kang
Keyword(s):  
Geostationary Satellite ◽  
Asia Pacific ◽  
Future Research ◽  
Ozone Monitoring Instrument ◽  
Single Observation ◽  
Vicarious Calibration ◽  
Monitoring Instrument ◽  
Convective Clouds ◽  
Observation Area ◽  
Deep Convective Clouds

As one of geostationary earth orbit constellation for environmental monitoring over the next decade, the Geostationary Environment Monitoring Spectrometer (GEMS) has been designed to observe the Asia-Pacific region to provide information on atmospheric chemicals, aerosols, and cloud properties. In order to continuously monitor sensor performance after its launch in early 2020, we suggest in this paper deep convective clouds (DCCs) as a possible target for the vicarious calibration of the GEMS, the first ultraviolet and visible hyperspectral sensor onboard a geostationary satellite. The Tropospheric Monitoring Instrument (TROPOMI) and the Ozone Monitoring Instrument (OMI) are used as a proxy for GEMS, and a conventional DCC-detection approach applying a thermal threshold test is used for DCC detection based on collocations with the Advanced Himawari Imager (AHI) onboard the Himawari-8 geostationary satellite. DCCs are frequently detected over the GEMS observation area at an average of over 200 pixels within a single observation scene. Considering the spatial resolution of the GEMS (3.5 × 8 km2), which is similar to the TROPOMI and its temporal resolution (eight times a day), the availability of DCCs is expected to be sufficient for the vicarious calibration of the GEMS. Inspection of the DCC reflectivity spectra estimated from OMI and TROPOMI data also shows promising results. The estimated DCC spectra are in good agreement within a known uncertainty range with comparable spectral features even with different observation geometries and sensor characteristics. When DCC detection is improved further by applying both visible and infrared tests, the variability of DCC reflectivity from TROPOMI data is reduced from 10% to 5%. This is mainly due to the efficient screening out of cold, thin cirrus clouds in the visible test and of bright, warm clouds in the infrared test. Precise DCC detection is also expected to contribute to the accurate characterization of cloud reflectivity, which will be investigated further in future research.

scholarly journals A New Potential of the Deep Convective Clouds as the Calibration Target for a Geostationary UV/VIS Hyperspectral Spectrometer

2019 ◽  
Author(s):  
Ye Eun Lee ◽  
Myoung-Hwan Ahn ◽  
Mina Kang
Keyword(s):  
Promising Result ◽  
Geostationary Satellite ◽  
Asia Pacific ◽  
Ozone Monitoring Instrument ◽  
Single Observation ◽  
Vicarious Calibration ◽  
Monitoring Instrument ◽  
Convective Clouds ◽  
Observation Area ◽  
Deep Convective Clouds

As one of GEO-constellation for environmental monitoring in the next decade, Geostationary Environment Monitoring Spectrometer (GEMS) is designed to observe the Asia Pacific region to provide the information on the atmospheric chemicals, aerosol and cloud properties. For the continuous monitoring of the sensor performance after its launch in early 2020, here we suggest deep convective clouds (DCCs) as a possible target for the vicarious calibration of GEMS, the first UV/VIS hyperspectral sensor onboard a geostationary satellite. Tropospheric Monitoring Instrument (TROPOMI) and Ozone Monitoring Instrument (OMI) are used as a proxy of GEMS, and a conventional DCC detection approach applying the thermal threshold test is used for the DCC detection based on the collocations with Advance Himawari-8 Imager (AHI) onboard Himawari-8 geostationary satellite. DCCs are frequently detected over the GEMS observation area on average over 200 pixels in a single observation scene. Considering the spatial resolution of GEMS, 3.5 km×7 km which is similar to TROPOMI, and its temporal resolution (8 times a day), availability of DCCs for vicarious calibration of GEMS is expected to be sufficient. Inspection of the DCC reflectivity spectra estimated from the OMI and TROPOMI data also shows a promising result. Even though, their observation geometry and sensor characteristics are quite a different, the estimated DCC spectra agree quite a well within a known uncertainty range with comparable spectral features. When the DCC detection is further improved by applying both visible and infrared tests, the variability of DCC reflectivity from the TROPOMI data is reduced by half, from 10% to 5%. This is mainly due to the efficient screening of cold thin cirrus with the visible test and of bright warm clouds with the infrared test. The precise DCC detection is also expected to contribute to the accurate characterization of the cloud reflectivity, which will be further investigated.

scholarly journals Ozone mixing ratios inside tropical deep convective clouds from OMI satellite measurements

2008 ◽  
Vol 8 (4) ◽  
pp. 16381-16407
Author(s):  
J. R. Ziemke ◽  
J. Joiner ◽  
S. Chandra ◽  
P. K. Bhartia ◽  
A. Vasilkov ◽  
...  
Keyword(s):  
Radar Data ◽  
Mixing Ratio ◽  
Ozone Monitoring Instrument ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
A New Technique ◽  
Oceanic Boundary Layer ◽  
Column Ozone

Abstract. We have developed a new technique for estimating ozone mixing ratio inside deep convective clouds. The technique uses the concept of an optical centroid cloud pressure that is indicative of the photon path inside clouds. Radiative transfer calculations based on realistic cloud vertical structure as provided by CloudSat radar data show that because deep convective clouds are optically thin near the top, photons can penetrate significantly inside the cloud. This photon penetration coupled with in-cloud scattering produces optical centroid pressures that are hundreds of hPa inside the cloud. We use the measured column ozone and the optical centroid cloud pressure derived using the effects of rotational-Raman scattering to estimate O3 mixing ratio in the upper regions of deep convective clouds. The data are obtained from the Ozone Monitoring Instrument (OMI) aboard NASA's Aura satellite. Our results show that low O3 concentrations in these clouds are a common occurrence throughout much of the tropical Pacific. Ozonesonde measurements in the tropics following convective activity also show very low concentrations of O3 in the upper troposphere. These low amounts are attributed to vertical injection of ozone poor oceanic boundary layer air during convection into the upper troposphere followed by convective outflow. Over South America and Africa, O3 mixing ratio inside deep convective clouds often exceeds 50 ppbv which is comparable to mean background (cloud-free) concentrations. These areas contain higher amounts of ozone precursors due to biomass burning and lightning. Assuming that O3 is well mixed (i.e. constant mixing ratio with height) up to the tropopause, we can estimate the stratospheric column O3 over clouds. Stratospheric column ozone derived in this manner agrees well with that retrieved independently with the Aura Microwave Limb Sounder (MLS) instrument and thus provides a consistency check of our method.

Analysis on spectral reflectivity of deep convective clouds towards vicarious calibration of UV/VIS hyperspectral instruments onboard geostationary satellites

2020 ◽  
Author(s):  
Yeeun Lee ◽  
Myoung-Hwan Ahn ◽  
Mina Kang
Keyword(s):  
Detection Method ◽  
Hyperspectral Data ◽  
Spectral Radiance ◽  
Atmospheric Effects ◽  
Detection Thresholds ◽  
Vicarious Calibration ◽  
Convective Clouds ◽  
Cloud Properties ◽  
Deep Convective Clouds ◽  
Environmental Sensor

<p>To meet the increasing demand for obtaining reliable information on the atmospheric distribution of trace gases and aerosols, GEO-constellation consisting of Geostationary Korean Multi-Purpose Satellite-2B (GK-2B), Tropospheric Emissions: Monitoring Pollution and Sentinel-4 are planned to be operated in this decade. As one of the environmental instruments, Geostationary Environment Monitoring Spectrometer (GEMS) onboard GK-2B planned to launch in February 2020 is designed to provide spectral radiance in the wavelength range of 300-500 nm as observing the tropical western Pacific region. To prepare a means of monitoring the calibration accuracy of GEMS, we aim to evaluate the feasibility of deep convective clouds (DCCs) as a possible target for vicarious calibration of GEMS. While the DCC calibration technique has been continuously verified from various meteorological satellite programs, it has been rarely researched in the ultraviolet and visible spectral region especially for the hyperspectral data of the environmental sensor. To finely detect DCCs reflecting stable signal throughout the spectral range of GEMS, we update the DCC detection thresholds based on the conventional detection method by applying both visible and infrared detection thresholds. To examine the effectiveness of the detection, Tropospheric Monitoring Instrument (TROPOMI) onboard Sentinel-5 Precursor is used as a proxy of GEMS. Advanced Himawari Imager onboard Himawari-8 is also used to construct the collocated data with TROPOMI since the environmental sensor only provides spectral radiance at shorter wavelengths. The DCCs detected by the updated thresholds show higher reflectivity over 0.9 as presenting homogeneous spectral features even at the Fraunhofer lines in which the atmospheric effects are prominent. Cloud properties such as the cloud optical thickness and cloud top height also become relatively homogeneous when both visible and infrared thresholds are used for the DCC detection since both radiation thresholds can be complement to limit the cloud properties of the detected clouds. With the detailed results, bidirectional reflectance distribution function (BRDF) is also to be estimated by applying the updated DCC detection method hereafter in the study.</p>

scholarly journals Ozone mixing ratios inside tropical deep convective clouds from OMI satellite measurements

2009 ◽  
Vol 9 (2) ◽  
pp. 573-583 ◽  
Author(s):  
J. R. Ziemke ◽  
J. Joiner ◽  
S. Chandra ◽  
P. K. Bhartia ◽  
A. Vasilkov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radar Data ◽  
Mixing Ratio ◽  
Ozone Monitoring Instrument ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
Oceanic Boundary Layer ◽  
Column Ozone

Abstract. We have developed a new technique for estimating ozone mixing ratio inside deep convective clouds. The technique uses the concept of an optical centroid cloud pressure that is indicative of the photon path inside clouds. Radiative transfer calculations based on realistic cloud vertical structure as provided by CloudSat radar data show that because deep convective clouds are optically thin near the top, photons can penetrate significantly inside the cloud. This photon penetration coupled with in-cloud scattering produces optical centroid pressures that are hundreds of hPa inside the cloud. We combine measured column ozone and the optical centroid cloud pressure derived using the effects of rotational-Raman scattering to estimate O3 mixing ratio in the upper regions of deep convective clouds. The data are obtained from the Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite. Our results show that low O3 concentrations in these clouds are a common occurrence throughout much of the tropical Pacific. Ozonesonde measurements in the tropics following convective activity also show very low concentrations of O3 in the upper troposphere. These low amounts are attributed to vertical injection of ozone poor oceanic boundary layer air during convection into the upper troposphere followed by convective outflow. Over South America and Africa, O3 mixing ratios inside deep convective clouds often exceed 50 ppbv which are comparable to mean background (cloud-free) amounts and are consistent with higher concentrations of injected boundary layer/lower tropospheric O3 relative to the remote Pacific. The Atlantic region in general also consists of higher amounts of O3 precursors due to both biomass burning and lightning. Assuming that O3 is well mixed (i.e., constant mixing ratio with height) up to the tropopause, we can estimate the stratospheric column O3 over clouds. Stratospheric column ozone derived in this manner agrees well with that retrieved independently with the Aura Microwave Limb Sounder (MLS) instrument and thus provides a consistency check of our method.

Vicarious calibration of S-NPP/VIIRS day–night band using deep convective clouds

2015 ◽  
Vol 158 ◽  
pp. 42-55 ◽  
Author(s):  
Shuo Ma ◽  
Wei Yan ◽  
Yun-Xian Huang ◽  
Wei-Hua Ai ◽  
Xianbin Zhao
Keyword(s):  
Vicarious Calibration ◽  
Convective Clouds ◽  
Deep Convective Clouds

Science objectives of the ozone monitoring instrument

2006 ◽  
Vol 44 (5) ◽  
pp. 1199-1208 ◽  
Author(s):  
P.F. Levelt ◽  
E. Hilsenrath ◽  
G.W. Leppelmeier ◽  
G.H.J. van den Oord ◽  
P.K. Bhartia ◽  
...  
Keyword(s):  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring
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