Home  About us  Contact
 

Measuring Mission (measuring + mission)

Distribution by Scientific Domains
Earth and Environmental Science75%

Kinds of Measuring Mission

  • rainfall measuring mission
    		•
  • tropical rainfall measuring mission
    		•

    Selected Abstracts

    Freezing height distribution in the tropics

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2003
    Merhala Thurai
    Abstract The calculation of fade margins required to meet the user-specified availability criteria needs to take into consideration a number of meteorological factors specific to the earth-station location. One such factor is the annual average of the freezing level height. Information on this height is available in ITU-R Recommendation P. 839-3, which provides contours that are generated on a 1.5° by 1.5° latitude by longitude resolution grid. This paper compares these heights with the bright-band heights (BBH) obtained from the precipitation radar on-board the TRMM (Tropical Rainfall Measuring Mission) satellite. Four years of TRMM radar data have been analysed, and their averages are compared within the latitude range covered by the satellite orbit (35°N to 35°S). Comparisons show that the radar bright-band heights typically occur 300 m below the 0°C isotherm heights. However, results also indicate that this difference may be latitude dependent. Also examined are the year-to-year variability and the seasonal variation. In the former case, only 1998 showed BBH values which are somewhat higher in tropical regions, this year having had one of the strongest El Niño events recorded. In the latter case, results show significant seasonal variation, becoming more pronounced at higher latitudes. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    A contribution by ice nuclei to global warming

    THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 643 2009
    Xiping Zeng
    Abstract Ice nuclei (IN) significantly affect clouds via supercooled droplets, that in turn modulate atmospheric radiation and thus climate change. Since the IN effect is relatively strong in stratiform clouds but weak in convective ones, the overall effect depends on the ratio of stratiform to convective cloud amount. In this paper, ten years of TRMM (Tropical Rainfall Measuring Mission) satellite data are analyzed to confirm that stratiform precipitation fraction increases with increasing latitude, which implies that the IN effect is stronger at higher latitudes. To quantitatively evaluate the IN effect versus latitude, large-scale forcing data from ten field campaigns are used to drive a cloud-resolving model to generate long-term cloud simulations. As revealed in the simulations, the increase in the net downward radiative flux at the top of the atmosphere from doubling the current IN concentrations is larger at higher latitude, which is attributed to the meridional tendency in the stratiform precipitation fraction. Surface warming from doubling the IN concentrations, based on the radiative balance of the globe, is compared with that from anthropogenic CO2. It is found that the former effect is stronger than the latter in middle and high latitudes but not in the Tropics. With regard to the impact of IN on global warming, there are two factors to consider: the radiative effect from increasing the IN concentration and the increase in IN concentration itself. The former relies on cloud ensembles and thus varies mainly with latitude. In contrast, the latter relies on IN sources (e.g. the land surface distribution) and thus varies not only with latitude but also longitude. Global desertification and industrialization provide clues on the geographic variation of the increase in IN concentration since pre-industrial times. Thus, their effect on global warming can be inferred and can then be compared with observations. A general match in geographic and seasonal variations between the inferred and observed warming suggests that IN may have contributed positively to global warming over the past decades, especially in middle and high latitudes. Copyright © 2009 Royal Meteorological Society [source]

    Diurnal and semidiurnal rainfall cycles during the rain season in SW Amazonia, observed via rain gauges and estimated using S-band radar

    ATMOSPHERIC SCIENCE LETTERS, Issue 2 2009
    Cláudio Moisés Santos e Silva
    Abstract The rainfall field estimated by an S-band radar was evaluated with rain gauges network measurements during the Tropical Rainfall Measuring Mission and Large-Scale Biosphere,Atmosphere Experiment in Amazonia (TRMM-LBA), then the daily variability associated with the presence (absence) of the South Atlantic convergence zone (SACZ) were studied. The results showed the high spatial variability of the rainfall over southwest (SW) Amazonia and suggest that local mechanisms (topography and/or local circulations induced by contrast of vegetation) may be associated with heavy rainfall episodes; moreover, it was possible to observe the squall line influence on the diurnal and semidiurnal cycles. Copyright © 2009 Royal Meteorological Society [source]

    Variability in sea-surface temperature and winds in the tropical south-east Atlantic Ocean and regional rainfall relationships

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2009
    J. C. Hermes
    Abstract Variability in sea-surface temperature (SST) and winds in the Angola Benguela frontal zone (ABFZ) in the tropical south-east Atlantic Ocean has previously been shown to be important for regional fisheries and for seasonal rainfall anomalies over Angola/Namibia in austral summer and coastal West Africa in boreal summer. This study investigates intraseasonal variability in winds and SST over this region using QuikSCAT and tropical rainfall measuring mission (TRMM) satellite data for 1999,2004. Wavelet analyses reveal periods of relatively strong power in the 20,30 or 30,64 day frequency bands throughout the record but that there is substantial interannual variability in the occurrence of these intraseasonal oscillations. The implications of this variability for seasonal rainfall anomalies during the main rainy seasons in southern Africa (austral summer) and coastal West Africa (boreal summer) are discussed. Copyright © 2008 Royal Meteorological Society [source]