Search

Your search keyword '"Nozomu Ohkawara"' showing total 3 results
Start Over Author "Nozomu Ohkawara" Topic ozone
3 results on '"Nozomu Ohkawara"'

1. Twenty-five years of spectral UV-B measurements over Canada, Europe and Japan: Trends and effects from changes in ozone, aerosols, clouds, and surface reflectivity

Author

J. Kapsomenakis, Nozomu Ohkawara, Hugo De Backer, Vitali Fioletov, Alkiviadis F. Bais, Ann R. Webb, Ilias Fountoulakis, Maria-Elissavet Koukouli, Christos Zerefos, Kaisa Lakkala, and Tomi Karppinen

Subjects
Global and Planetary Change, Ozone, 010504 meteorology & atmospheric sciences, Cloud cover, Irradiance, Northern Hemisphere, 010501 environmental sciences, Atmospheric sciences, Solar irradiance, 01 natural sciences, Aerosol, Latitude, chemistry.chemical_compound, chemistry, General Earth and Planetary Sciences, Environmental science, sense organs, Absorption (electromagnetic radiation), 0105 earth and related environmental sciences
Abstract

Spectral UV records of solar irradiance at stations over Europe, Canada, and Japan were used to study long-term trends at 307.5 nm for a 25-year period, from 1992 to 2016. Ground-based measurements of total ozone, as well as satellite measurements of the Aerosol Index, the Total Cloud Cover and the surface reflectivity were also used in order to attribute the estimated changes of the UV to the corresponding changes of these factors. The present study shows that over the Northern Hemisphere, the long-term changes in UV-B radiation reaching the Earth’s surface vary significantly over different locations, and that the main drivers of these variations are changes in aerosols and total ozone. At high latitudes, part of the observed changes may also be attributed to changes in the surface reflectivity. Over Japan, the UV-B irradiance at 307.5 nm has increased significantly by 3%/decade during the past 25 years, possibly due to the corresponding significant decrease of its absorption by aerosols. It was found that the greatest part of this increase took place before the mid-2000s. The only European station, over which UV radiation increases significantly, is that of Thessaloniki, Greece. Analysis of the clear-sky irradiance for the particular station shows increasing irradiance at 307.5 nm by 3.5%/decade during the entire period of study, with an increasing rate of change during the last decade, possibly again due to the decreasing absorption by aerosols.

Published
2018

2. Optimal use of Prede POM sky radiometer for aerosol, water vapor, and ozone retrievals.

Author

Rei Kudo, Diémoz, Henri, Estellés, Victor, Campanelli, Monica, Masahiro Momoi, Marenco, Franco, Ryder, Claire L., Osamu Ijima, Akihiro Uchiyama, Kouichi Nakashima, Akihiro Yamazaki, Ryoji Nagasawa, Nozomu Ohkawara, and Haruma Ishida

Subjects
WATER vapor, MINERAL dusts, AEROSOLS, OZONE, RADIOMETERS, PLANE geometry, OPTICAL properties
Abstract

The Prede POM sky radiometer is a filter radiometer deployed worldwide in the SKYNET international network. A new method called, Skyrad pack MRI version 2 (MRI v2), is here presented, to retrieve aerosol properties (size distribution, real and imaginary parts of the refractive index, single-scattering albedo, asymmetry factor, lidar ratio, and linear depolarization ratio), and water vapor and ozone column concentrations from the sky radiometer measurements. MRI v2 overcomes two limitations of previous methods (Skyrad pack versions 4.2 and 5, and MRI version 1). One is the use of all the wavelengths of 315, 340, 380, 400, 500, 675, 870, 940, 1020, 1627, and 2200 nm, if available from the sky radiometers, for example, in POM-02 models. The previous methods cannot use the wavelengths of 315, 940, 1627, and 2200 nm. This enables us to provide improved estimates of the aerosol optical properties, covering almost all the wavelengths of solar radiation. The other is the use of measurements in the principal plane geometry in addition to the solar almucantar plane geometry that is used in the previous versions. The measurements in the principal plane are regularly performed, however they are currently not exploited despite being useful in the case of small solar zenith angles, when the scattering angle distribution for almucantars becomes too small to yield useful information. Moreover, in the inversion algorithm, MRI v2 optimizes the smoothness constraints of the spectral dependencies of the refractive index and size distribution, and changes the contribution of the diffuse radiances to the cost function according to the aerosol optical depth. These overcome issues with the estimation of the size distribution and single-scattering albedo in the Skyrad pack version 4.2. The scattering model used here allows for nonspherical particles, improving results for mineral dust and permitting to evaluate the depolarization ratio. An assessment of the retrieval uncertainties using synthetic measurement show that best performance is obtained when the aerosol optical depths is larger than 0.2 at 500 nm. Improvements over the Skyrad pack versions 4.2 and 5 are obtained for the retrieved size distribution, imaginary part of the refractive index, single-scattering albedo, and lidar ratio at Tsukuba, Japan, while yielding comparable retrievals of the aerosol optical depth, real part of the refractive index, and asymmetry factor. A radiative closure study using surface solar irradiances from Baseline Surface Radiation Network and the parameters retrieved from MRI v2 showed consistency, with a positive bias of the simulated global irradiance, about +24 Wm-2 (+3 %). Furthermore, the MRI v2 retrievals of the refractive index, single-scattering albedo, asymmetry factor, and size distribution have been found in agreement with integrated profiles of aircraft in-situ measurements of two Saharan dust events at the Cape Verde archipelago, during the SAVEX-D 2015 field campaign. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

3. Validation of 10-year SAO OMI Ozone Profile (PROFOZ) product using ozonesonde observations

Author

Tristan J. Hall, Bertrand Calpini, Bogumil Kois, Roeland Van Malderen, René Stübi, Marion Marchand, Marc Allaart, Masatomo Fujiwara, Thierry Leblanc, Anne M. Thompson, M.B. Tully, Richard Querel, Everette Joseph, Françoise Posny, Ghassan Taha, Kai Yang, Zhaonan Cai, Giovanni Laneve, Michael J. Newchurch, Manvendra K. Dubey, Gary A. Morris, Hugo De Backer, Rinus Scheele, Xiong Liu, Jacquelyn C. Witte, Kenneth R. Minschwaner, Nozomu Ohkawara, Ankie Piters, Kelly Chance, Shin-Ya Ogino, Margarita Yela, Ninong Komala, Emilio Cuevas-Agulló, H. B. Selkirk, Sophie Godin-Beekmann, Guanyu Huang, Manuel Cupeiro, Valérie Thouret, Holger Vömel, Russell C. Schnell, Gerrie Coetzee, Pawan K. Bhartia, Masato Shiotani, Gérard Ancellet, Otto Schrems, Bryan J. Johnson, Gert König-Langlo, Rigel Kivi, F. J. Schmidlin, Peter von der Gathen, P. Skrivankova, David W. Tarasick, Henry E. Fuelberg, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Department of Atmospheric and Oceanic Science [College Park] (AOSC), University of Maryland [College Park], University of Maryland System-University of Maryland System, NASA Goddard Space Flight Center (GSFC), Royal Netherlands Meteorological Institute (KNMI), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Payerne Aerological Station, Federal Office of Meteorology and Climatology MeteoSwiss, South African Weather Service (SAWS), Izaña Atmospheric Research Center (IARC), Agencia Estatal de Meteorología (AEMet), National Meteorological Service [Ushuaia], Institut Royal Météorologique de Belgique [Bruxelles] (IRM), Los Alamos National Laboratory (LANL), Department of Earth, Ocean and Atmospheric Science [Tallahassee] (FSU | EOAS), Florida State University [Tallahassee] (FSU), Faculty of Environmental Earth Science [Sapporo], Hokkaido University [Sapporo, Japan], STRATO - LATMOS, ESRL Global Monitoring Laboratory [Boulder] (GML), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Atmospheric Sciences Research Center (ASRC), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), Finnish Meteorological Institute (FMI), Institute of Meteorology and Water Management - National Research Institute (IMGW - PIB), Indonesian National Institute of Aeronautics and Space (LAPAN), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Earth Observation Satellite Images Applications Laboratory (EOSIAL), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Physics [Socorro], New Mexico Institute of Mining and Technology [New Mexico Tech] (NMT), St. Edward's University, Department of Atmospheric Science [Huntsville], University of Alabama in Huntsville (UAH), Department of Coupled Ocean-Atmosphere-Land Processes Research (DCOP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Global Environment and Marine Department [Tokyo], Japan Meteorological Agency (JMA), Laboratoire de l'Atmosphère et des Cyclones (LACy), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France, Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), National Institute of Water and Atmospheric Research [Lauder] (NIWA), Universities Space Research Association (USRA), Research Institute for Sustainable Humanosphere (RISH), Kyoto University [Kyoto], Czech Hydrometeorological Institute (CHMI), Environment and Climate Change Canada, Laboratoire d'aérologie (LAERO), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Australian Bureau of Meteorology [Melbourne] (BoM), Australian Government, Earth Observing Laboratory [Boulder] (EOL), National Center for Atmospheric Research [Boulder] (NCAR)-University Corporation for Atmospheric Research (UCAR), Science Systems and Applications, Inc. [Lanham] (SSAI), Instituto Nacional de Técnica Aeroespacial (INTA), Harvard University-Smithsonian Institution, Institut Royal Météorologique de Belgique [Bruxelles] - Royal Meteorological Institute (IRM), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Kyoto University, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Cloud cover, 0211 other engineering and technologies, 02 engineering and technology, 01 natural sciences, Latitude, Troposphere, Ozone layer, lcsh:TA170-171, Stratosphere, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, validation, Ozone Monitoring Instrument, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:TA715-787, Anomaly (natural sciences), OMI, lcsh:Earthwork. Foundations, ozone, lcsh:Environmental engineering, Trace gas, 13. Climate action, Climatology, Environmental science
Abstract

We validate the Ozone Monitoring Instrument (OMI) Ozone Profile (PROFOZ) product from October 2004 through December 2014 retrieved by the Smithsonian Astrophysical Observatory (SAO) algorithm against ozonesonde observations. We also evaluate the effects of OMI row anomaly (RA) on the retrieval by dividing the dataset into before and after the occurrence of serious OMI RA, i.e., pre-RA (2004–2008) and post-RA (2009–2014). The retrieval shows good agreement with ozonesondes in the tropics and midlatitudes and for pressure ∼ 50 hPa after applying OMI averaging kernels to ozonesonde data. The MBs of the stratospheric ozone column (SOC, the ozone column from the tropopause pressure to the ozonesonde burst pressure) are within 2 % with SDs of ∼ 50 hPa. The SOC MBs increase up to 3 % with SDs as great as 6 % and the TOC SDs increase up to 30 %. The comparison generally degrades at larger solar zenith angles (SZA) due to weaker signals and additional sources of error, leading to worse performance at high latitudes and during the midlatitude winter. Agreement also degrades with increasing cloudiness for pressure > ∼ 100 hPa and varies with cross-track position, especially with large MBs and SDs at extreme off-nadir positions. In the tropics and midlatitudes, the post-RA comparison is considerably worse with larger SDs reaching 2 % in the stratosphere and 8 % in the troposphere and up to 6 % in TOC. There are systematic differences that vary with latitude compared to the pre-RA comparison. The retrieval comparison demonstrates good long-term stability during the pre-RA period but exhibits a statistically significant trend of 0.14–0.7 % year−1 for pressure

Published
2017

Catalog

Books, media, physical & digital resources
See catalog results