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17
Quantifying global uncertainties in a simple microwave rainfall algorithm
- J. Atmos. Oceanic Technol
, 2006
"... While a large number of methods exist in the literature for retrieving rainfall from passive microwave brightness temperatures, little has been written about the quantitative assessment of the expected uncer-tainties in these rainfall products at various time and space scales. The latter is the resu ..."
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While a large number of methods exist in the literature for retrieving rainfall from passive microwave brightness temperatures, little has been written about the quantitative assessment of the expected uncer-tainties in these rainfall products at various time and space scales. The latter is the result of two factors: sparse validation sites over most of the world’s oceans, and algorithm sensitivities to rainfall regimes that cause inconsistencies against validation data collected at different locations. To make progress in this area, a simple probabilistic algorithm is developed. The algorithm uses an a priori database constructed from the Tropical Rainfall Measuring Mission (TRMM) radar data coupled with radiative transfer computations. Unlike efforts designed to improve rainfall products, this algorithm takes a step backward in order to focus on uncertainties. In addition to inversion uncertainties, the construction of the algorithm allows errors resulting from incorrect databases, incomplete databases, and time- and space-varying databases to be examined. These are quantified. Results show that the simple algorithm reduces errors introduced by imperfect knowledge of precipitation radar (PR) rain by a factor of 4 relative to an algorithm that is tuned to the PR rainfall. Database completeness does not introduce any additional uncertainty at the global scale, while climatologically distinct space/time domains add approximately 25 % uncertainty that cannot be detected by a radiometer alone. Of this value, 20 % is attributed to changes in cloud morphology and microphysics, while 5 % is a result of changes in the rain/no-rain thresholds. All but 2%–3 % of this variability can be accounted for by considering the implicit assumptions in the algorithm. Additional uncertainties introduced by the details of the algorithm formulation are not quantified in this study because of the need for independent measurements that are beyond the scope of this paper. A validation strategy for these errors is outlined. 1.
C.: A neural network for real-time retrievals of PWV and LWP from arctic millimeter-wave ground-based observations
- IEEE T. Geosci. Remote
"... 2 ) and a retrieval error varying from 1 to about 10 g/m 2 when the PWV amount is between 1 and 10 mm. As an independent validation of the LWP retrieval, the longwave downwelling surface flux was computed and compared with observations. The comparison shows a significant improvement with respect to ..."
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2 ) and a retrieval error varying from 1 to about 10 g/m 2 when the PWV amount is between 1 and 10 mm. As an independent validation of the LWP retrieval, the longwave downwelling surface flux was computed and compared with observations. The comparison shows a significant improvement with respect to the MWR statistical retrievals, particularly for LWP amounts of less than 60 g/m 2 . This paper shows that the GVR alone can provide overall improved PWV and LWP retrievals when the PWV amount is less than 10 mm, and, when combined with the MWR, can provide improved retrievals over the whole water-vapor range.
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
"... Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments ..."
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Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
International Journal of Intelligent Systems and Applications in Engineering
, 2014
"... Abstract: In this work, we will adapt the NAW (Nagri, Adler and Wetzel), precipitation estimation approach to the north Algeria events using the Meteosat Second Generation (MSG) satellite images. The tests are carried out on seven areas of northern Algeria: Sidi Bel Abbes, Oran Port, Algiers Port, D ..."
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Abstract: In this work, we will adapt the NAW (Nagri, Adler and Wetzel), precipitation estimation approach to the north Algeria events using the Meteosat Second Generation (MSG) satellite images. The tests are carried out on seven areas of northern Algeria: Sidi Bel Abbes, Oran Port, Algiers Port, Dar El Beida, Bedjaia, Jijel-Achouat and Annaba, in winter 2006. The NAW approach is applied by thresholding to temperature from 253 K. The validation is performed by comparaison the estimated rainfall to in situ measures collected by the National Office of Meteorology in Dar El Beida (Algeria). We use the infrared data (10.8µm channel) of SEVIRI sensor in this study. The results obtained indicate that the NAW approach gives satisfactory results for the rain rates: 4mm/h assigned to the coldest 10%, 2mm/h assigned to the next 40 % and 0mm/h given to the remaining 50 % of the area defined as cloud. The rain rate 8mm/h assigned to the coldest 10 % of the pixels in the cloud applied for the convective clouds observed for tropical regions are not valid for the Algerian climate, especially for the stratiform clouds type.
Open Access Drinking Water Engineering and Science
"... www.earth-syst-sci-data.net/2/215/2010/ doi:10.5194/essd-2-215-2010 ..."
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
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"... Final Report on the Visiting Scientist activities: Refinement and operational implementation of a rain rate algorithm based on AMSU/MHS and rain gauge data over H-SAF area ..."
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Final Report on the Visiting Scientist activities: Refinement and operational implementation of a rain rate algorithm based on AMSU/MHS and rain gauge data over H-SAF area
Date Dedication
, 2013
"... To our God, the creator... The breath of God produces ice, and the broad waters become frozen. He loads the clouds with moisture; he scatters his lightning through them. At his direction they swirl around over the face of the whole earth to do whatever he commands them. He brings the clouds to punis ..."
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To our God, the creator... The breath of God produces ice, and the broad waters become frozen. He loads the clouds with moisture; he scatters his lightning through them. At his direction they swirl around over the face of the whole earth to do whatever he commands them. He brings the clouds to punish people, or to water his earth and show his love.
TOWARDS IMPROVEMENT OF HOAPS: NEW ESTIMATES OF EVAPORATION AND PRECIPITATION FROM TRMM
"... This note describes new developments of retrievals of basic state variables at the air-sea interface as well as rainfall, both essential for the computation of turbulent heat fluxes and the water budget at the sea surface. The Visible Infrared Scanner (VIRS) and the Tropical Rainfall Measuring Missi ..."
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This note describes new developments of retrievals of basic state variables at the air-sea interface as well as rainfall, both essential for the computation of turbulent heat fluxes and the water budget at the sea surface. The Visible Infrared Scanner (VIRS) and the Tropical Rainfall Measuring Mission (TRMM) microwave imager (TMI) are used to retrieve sea surface temperature, near-surface air specific humidity, and wind speed. All three variables are used within a bulk parameterization scheme to compute latent heat fluxes employing some additional empirical assumptions. Results of comparisons to buoy measurements led to several adjustments of the retrieval schemes. The application of the retrievals show that the sampling is sufficient to compute monthly averages. A comparison to HOAPS data showed substantially differences between the data sets primarily in the derived wind speed. For precipitation a new computationally efficient algorithm making use of TMI and the Precipitation Radar (PR) observations has been developed. The technique consists of a standard TMI algorithm that is compared to PR estimates of near-surface rainfall at TMI s spatial resolution and a reference altitude. The difference between TMI and PR estimates appear to be rather systematic which may be translated into a globally constant calibration thus easy to transfer to other passive microwave radiometers on other satellites.
