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  • 1
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    Highlights from the 1998-2000 SHADOZ (Southern Hemisphere Additional Ozonesondes) Satellite Validation Project (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: There are three years of data (more than 1000 individual ozone profiles) available from a network of 10 southern hemisphere tropical and subtropical stations, designated the Southern Hemisphere ADditional OZonesondes (SHADOZ) project. Since late 1999, a tropical station in the northern hemisphere (Paramaribo, Surinam; lat/long) joined SHADOZ, providing coordinated weekly ozone and radiosonde data from the surface to approx. 7 hPa for satellite validation, process studies, and model evaluation. Profiles are also collected at: Ascension Island; Nairobi, Kenya; Irene, South Africa; R (union Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. The archive, station characteristics and photos are available at http://code9l6.gsfc.nasa.gov/Data_ services/shadoz〉. SHADOZ ozone time-series and profiles in 1998-2000 display highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Integrated total ozone column amounts from the sondes are lower than independent measurements from a ground-based network and from the TOMS (Total Ozone Mapping Spectrometer) satellite (version 7 data).
    Keywords: Environment Pollution
    Type: AGU Spring Meeting; May 29, 2001 - Jun 02, 2001; Boston, MA; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Lidar observations and model studies of subvisible cloud formation at the tropical tropopause (2006)
    In:  [Poster] In: EGU General Assembly, 07.04, Vienna, Austria .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    PAPER (OCEANREP)
  • 3
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    Cirrus clouds, humidity, and dehydration at the tropical tropopause layer observed at Paramaribo/Suriname (5.8°N, 55.2°W) (2007)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Atmospheres, 112 (D3). D03209.
    Details
    Publication Date: 2018-02-06
    Description: In the framework of the European Project STAR the Mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI) was operated in Paramaribo, Suriname (5.8°N, 55.2°W), and carried out extensive observations of tropical cirrus clouds during the local dry season from 28 September 2004 to 16 November 2004. The coverage with ice clouds was very high with 81% in the upper troposphere (above 12 km). The frequency of occurrence of subvisual clouds was found to be clearly enhanced compared to similar observations performed with the same instrument at a station in the midlatitudes. The extinction-to-backscatter ratio of thin tropical cirrus is with 26 ± 7 sr significantly higher than that of midlatitude cirrus (16 ± 9 sr). Subvisual cirrus clouds often occur in the tropical tropopause layer (TTL) above an upper tropospheric inversion. Our observations show that the ice-forming ability of the TTL is very high. The transport of air in this layer was investigated by means of a newly developed trajectory model. We found that the occurrence of clouds is highly correlated with the temperature and humidity history of the corresponding air parcel. Air that experienced a temperature minimum before the measurement took place was generally cloud free, while air that was at its temperature minimum during the observation and thus was saturated contained ice. We also detected extremely thin cloud layers slightly above the temperature minimum in subsaturated air. The solid particles of such clouds are likely to consist of nitric acid trihydrate (NAT) rather than ice.
    Type: Article , PeerReviewed
    Format: text
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  • 4
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    Cirrus clouds, humidity, and dehydration in the tropical tropopause layer observed at Paramaribo, Suriname (5.8°N, 55.2°W) (2007)
    In:  EPIC3Journal of Geophysical Research, 112, D03209
    Details
    Publication Date: 2019-07-17
    Description: In the framework of the European Project STAR the mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI) was operated in Paramaribo/Suriname (5.8°, 55.2°W) and carried out extensive observations of tropical cirrus clouds during the fall dry season from September 28 to November 15 2004. With 81% the coverage with ice clouds was very high in the upper troposphere (above 12 km). The frequency of occurrence of subvisible clouds was found to be clearly enhanced compared to the midlatitudes. The extinction-to-backscatter ratio of thin tropical cirrus is with 26 ± 7 sr significantly higher than that of mid-latitude cirrus (16 ± 9 sr).Subvisible cirrus occur mostly in the tropical tropopause layer (TTL) abovean upper tropospheric inversion. The formation conditions of these cloudsand the dehydration of the TTL was investigated by means of a newly developed trajectory model. Clouds were assumed to occur when the relativehumidity above ice (RHI) exceeds 100% due to adiabatic cooling and subsequently the humidity is reduced to the saturation vapor pressure. This simple dehydration scheme yields an amazingly good agreement with cloud andhumidity observations at Paramaribo. However, it challenges the way cirrusformation is generally conceived, since high supersaturation were thoughtto be required. Our results suggest, that the inclination of the TTL to contain solid particles is rather high, even under modestly moist conditions. Wealso detected extremely thin layers of solid particles slightly above the temperature minimum in sub-saturated air which are possibly stabilized by HNO3.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Cirrus clouds and ice supersaturated regions observed by lidar and radiosondes. (2005)
    In:  EPIC3Joint CWVC and UTLS OZONE 'Water Vapour in the UTLS' Workshop: 5-7 July 2005, Lancaster, UK.
    Details
    Publication Date: 2019-07-17
    Description: With our mobile Aerosol Raman Lidar (MARL) we have performed field campaigns in the mid latitudes in 2003 (Lindenberg/Germany, 53°N, 15°E) and in the tropics in 2004/05(Paramaribo/Suriname, 6°N, 55°W). The lidar system detects aerosols and clouds in the UTLS region. It is capable of detecting thin cirrus including extremely thin clouds with optical depth below 10-3. The system measures cloud altitudes with high vertical and temporal resolution and determines the depolarisation and optical depth. It operates day and night. During daytime cloud types including contrails are classified with the help of a video camera. During the campaigns, water vapour was measured by means of balloon borne sondes (Vaisala RS80/RS90, 'Snow white' frost point hygrometer) and by the LIDAR using the Raman technique. We investigated the occurrence of ice supersaturated regions and their relation to the occurrence of clouds. The accuracy of the water vapour measurements needs to be critically evaluated for this purpose. The cloudiness in the upper troposphere was found to be very high in the tropics where in about 90% of all measured profiles cirrus was present. In the mid latitudes cirrus were found in 55% of the measurements.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 6
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    Cirrus clouds and ice supersaturated regions observed by Raman lidar and radiosondes. (2005)
    In:  EPIC3Proceedings of Water Vapour in the Upper Troposphere and Lower Stratosphere Workshop, Lancaster University, England 5th to 7th July 2005., pp. 30-31
    Details
    Publication Date: 2019-07-17
    Description: With our mobile Aerosol Raman Lidar (MARL) we have performed field campaigns in the mid latitudes in 2003 (Lindenberg/Germany, 53°N, 15°E) and in the tropics in 2004/05(Paramaribo/Suriname, 6°N, 55°W). The lidar system detects aerosols and clouds in the UTLS region. It is capable of detecting thin cirrus including extremely thin clouds with optical depth below 10-3. The system measures cloud altitudes with high vertical and temporal resolution and determines the depolarisation and optical depth. It operates day and night. During daytime cloud types including contrails are classified with the help of a video camera. During the campaigns, water vapour was measured by means of balloon borne sondes (Vaisala RS80/RS90, 'Snow white' frost point hygrometer) and by the LIDAR using the Raman technique. We investigated the occurrence of ice supersaturated regions and their relation to the occurrence of clouds. The accuracy of the water vapour measurements needs to be critically evaluated for this purpose. The cloudiness in the upper troposphere was found to be very high in the tropics where in about 90% of all measured profiles cirrus was present. In the mid latitudes cirrus were found in 55% of the measurements.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 7
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    Lidar observations and model studies of subvisible cloud formation at the tropical tropopause. (2006)
    In:  EPIC3EGU general assembly, Wien.-7.04.2006., 3
    Details
    Publication Date: 2019-07-17
    Description: The Mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI)was operated at Paramaribo/Suriname (5.8°N, 55.2°W) in the fall dry season from September 28 to November 15 in 2004 during a campaign of the EU project STAR. MARL is capable of detecting extremely thin, subvisible cirrus clouds in the tropical tropopause region (TTL). In 81% of the obtained 140 hours of observation time ice clouds were present in the upper troposphere (above 12 km). The frequency of occurrence of subvisible clouds was found to be clearly enhanced compared to themid-latitudes. The formation conditions of these clouds and the dehydration of the TTL was investigated by means of a newly developed trajectory model, where diabatic heating rates calculated from a radiative transfer model are used to determine the vertical motion. Subvisible cirrus clouds are shown to form due to slow ascent in the TTL. If these clouds were assumed to occur whenever the relative humidity above ice(RHI) exceeds 100% due to adiabatic cooling, a good agreement between the model and the observations is achieved. In some cases however, extremely thin layers of particles were observed at conditions were the air is not saturated. This indicates that these clouds rather consist of NAT than of water ice particles.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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