SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Ekström Mattias 1977 ) ;lar1:(cth);pers:(Eriksson Patrick 1964)"

Sökning: WFRF:(Ekström Mattias 1977 ) > Chalmers tekniska högskola > Eriksson Patrick 1964

  • Resultat 1-9 av 9
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Ekström, Mattias, 1977, et al. (författare)
  • Altitude resolved ice-fraction in the uppermost tropical troposphere
  • 2008
  • Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 35:2, s. L13822-
  • Tidskriftsartikel (refereegranskat)abstract
    • The exact nature of the processes responsible for the moistening of the upper tropical troposphere is still uncertain. Altitude resolved measurements of water vapor from Aura/Microwave Limb Sounder (MLS) and cloud ice from CloudSat are used to investigate the ratio of ice mass to total water. Horizontal and vertical ice-fraction distributions in the pressure range 100-316 hPa over the tropical region are presented. They reveal that the ice-fraction is generally low, less than 10% around 316 hPa in general and outside regions of deep convection in the altitude levels above. On the other hand, the ice-fraction can be significant at higher altitudes in large regions above deep convection, reaching values of ∼90%. Below the tropical tropopause layer (TTL) ice and water vapor distributions have similar spatial patterns indicating that water in both phases is transported up to the upper troposphere by the same processes. Over regions of strong deep convection where ice is transported into the TTL, the dissimilar patterns of ice and water vapor could be interpreted as that the cloud ice gives a limited final moistening effect. Copyright 2008 by the American Geophysical Union.
  •  
2.
  • Ekström, Mattias, 1977, et al. (författare)
  • Comparison of satellite limb-sounding humidity climatologies of the uppermost tropical troposphere
  • 2008
  • Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:2, s. 309-320
  • Tidskriftsartikel (refereegranskat)abstract
    • Humidity climatologies of the tropical uppermost troposphere from satellite limb emission measurements have been compared. Four instruments are considered; UARS-MLS, Odin-SMR, and Aura-MLS operating in the microwave region, and MIPAS in the infrared region. A reference for the comparison is obtained by MOZAIC in-situ measurements.The upper tropospheric humidity products were compared on basis of their empirical probability density functions and seasonally averaged horizontal fields at two altitude layers, 12 and 15 km. The probability density functions of the microwave datasets were found to be in very good agreement with each other, and were also consistent with MOZAIC. The average seasonal humidities differ with less than 10%RHi between the instruments, indicating that stated measurement accuracies of 20–30% are conservative estimates. The systematic uncertainty in Odin-SMR data due to cloud correction was also independently estimated to be 10%RHi. MIPAS humidity profiles were found to suffer from cloud contamination, with only 30% of the measurements reaching into the upper troposphere, but under clear-sky conditions there is a good agreement between MIPAS, Odin-SMR and Aura-MLS.Odin-SMR and the two MLS datasets can be treated as independent, being based on different underlying spectroscopy and technology. The good agreement between the microwave limb-sounders, and MOZAIC, is therefore an important step towards understanding the upper tropospheric humidity. The found accuracy of 10%RHi is approaching the level required to validate climate modelling of the upper troposphere humidity. The comparison of microwave and infrared also stresses that microwave limb-sounding is necessary for a complete view of the upper troposphere.
  •  
3.
  •  
4.
  • Eriksson, Patrick, 1964, et al. (författare)
  • Comparison between early Odin-SMR, Aura MLS and CloudSat retrievals of cloud ice mass in the upper tropical troposphere
  • 2008
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:7, s. 1937-1948
  • Tidskriftsartikel (refereegranskat)abstract
    • Emerging microwave satellite techniques are expected to provide improved global measurements of cloud ice mass. CloudSat, Aura MLS and Odin-SMR fall into this category and early cloud ice retrievals from these instruments are compared. The comparison follows the SMR retrieval product and is made for partial ice water columns above 12 km. None of the retrievals shows a significant degree of false cloud detections, the ratio between local mean values from the instruments is fairly constant and a consistent view of the geographical distribution of cloud ice is obtained. However, important differences on the absolute levels exist, where the overall mean is 9.6, 4.2 and 3.7 g m−2 for CloudSat, SMR and MLS, respectively. Assumptions about the particle size distribution (PSD) are a consideration for all three instruments and constitute the dominating retrieval uncertainty for CloudSat. The mean for CloudSat when applying the same PSD as for MLS and SMR was estimated to 6.3 g m−2. A second main consideration for MLS and SMR are the effects caused by the poorer spatial resolution: a possible vertical misplacement of retrieved values and an impact of cloud inhomogeneities. The latter effect was found to be the dominating retrieval uncertainty for SMR, giving a possible mean value range of 2.3–8.9 g m−2. The comparison indicates a common retrieval accuracy in the order of 70%. Already this number should suffice for improved validations of cloud ice parametrisation schemes in atmospheric models, but a substantially better consistency between the datasets should be attainable through an increased understanding of main retrieval error sources.
  •  
5.
  •  
6.
  •  
7.
  •  
8.
  •  
9.
  • Urban, Joachim, 1964, et al. (författare)
  • Odin/SMR Limb Observations of Stratospheric Trace Gases: Level 2 Processing of ClO, N2O, O3, and HNO3
  • 2005
  • Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 110:D14, s. 1-20
  • Tidskriftsartikel (refereegranskat)abstract
    • The Sub-Millimetre Radiometer (SMR) on board the Odin satellite, launched on 20 February 2001, observes key species with respect to stratospheric chemistry and dynamics such as O-3, ClO, N2O, and HNO3 using two bands centered at 501.8 and 544.6 GHz. We present the adopted methodology for level 2 processing and the achieved in-orbit measurement capabilities of the SMR radiometer for these species in terms of altitude range, altitude resolution, and measurement precision. The characteristics of the relevant level 2 data versions, namely version 1.2 of the operational processor as well as versions 222 and 223 of the reference code, are discussed and differences are evaluated. An analysis of systematic retrieval errors, resulting from spectroscopic and instrumental uncertainties, is also presented.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-9 av 9

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy