Journal cover Journal topic
Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

Journal metrics

  • IF value: 3.089 IF 3.089
  • IF 5-year<br/> value: 3.700 IF 5-year
    3.700
  • CiteScore<br/> value: 3.59 CiteScore
    3.59
  • SNIP value: 1.273 SNIP 1.273
  • SJR value: 2.026 SJR 2.026
  • IPP value: 3.082 IPP 3.082
  • h5-index value: 45 h5-index 45
https://doi.org/10.5194/amt-2017-277
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
24 Aug 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Measurement Techniques (AMT) and is expected to appear here in due course.
Noise performance of microwave humidity sounders over their life time
Imke Hans1, Martin Burgdorf1, Viju O. John2,3, Jonathan Mittaz4,5, and Stefan A. Buehler1 1Meteorologisches Institut, Centrum für Erdsystem- und Nachhaltigkeitsforschung (CEN), Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany
2European Organisation for the Exploitation of Meteorological Satellites, Eumetsat Allee 1, D-64295 Darmstadt, Germany
3Met Office Hadley Centre, FitzRoy Road, Exeter, Devon EX1 3PB, United Kingdom
4Department of Meteorology, University of Reading, Reading, RG6 6AL, UK
5National Physical Laboratory, Teddington, TW11 0LW, UK
Abstract. The microwave humidity sounders Special Sensor Microwave Water Vapour Profiler (SSMT-2), Advanced Microwave Sounding Unit-B (AMSU-B) and Microwave Humidity Sounder (MHS) to date have been providing data records for 25 years. So far, the data records lack uncertainty information essential for constructing consistent long time data series. In this study, we assess the quality of the recorded data with respect to the uncertainty caused by noise. We calculate the noise on the raw calibration counts from the deep space view (DSV) of the instrument and the Noise Equivalent Differential Temperature (NEΔT) as a measure for the radiometer sensitivity. For this purpose, we use the Allan Deviation that is not biased from an underlying varying mean of the data and that has been suggested only recently for application in atmospheric remote sensing. Moreover, we use the bias function related to the Allan Deviation to infer the underlying spectrum of the noise. As examples, we investigate the noise spectrum in flight for some instruments. For the assessment of the noise evolution in time, we provide a descriptive and graphical overview of the calculated NEΔT over the life span of each instrument and channel. This overview can serve as an easily accessible information for users interested in the noise performance of a specific instrument, channel and time. Within the time evolution of the noise, we identify periods of instrumental degradation, which manifest themselves in an increasing NEΔT, and periods of erratic behaviour, which show sudden increases of NEΔT interrupting the overall smooth evolution of the noise. From this assessment and subsequent exclusion of the aforementioned periods, we present a chart showing available data records with NEΔT < K. Due to overlapping life spans of the instruments, these reduced data records still cover without gaps the time since 1994 and may therefore serve as first step for constructing long time series. Our method for count noise estimation, that has been used in this study, will be used in the data processing to provide input values for the uncertainty propagation in the generation of a new set of Fundamental Climate Data Records (FCDR) that are currently produced in the project Fidelity and Uncertainty in Climate data records from Earth Observation (FIDUCEO).

Citation: Hans, I., Burgdorf, M., John, V. O., Mittaz, J., and Buehler, S. A.: Noise performance of microwave humidity sounders over their life time, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-277, in review, 2017.
Imke Hans et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC1: 'anonymous review', Anonymous Referee #1, 20 Sep 2017 Printer-friendly Version 
AC1: 'Reply to Referee1', Imke Hans, 22 Sep 2017 Printer-friendly Version 
 
RC2: 'Review AMT-2017-277', Anonymous Referee #2, 13 Oct 2017 Printer-friendly Version 
AC2: 'Reply to Referee 2', Imke Hans, 16 Oct 2017 Printer-friendly Version 
Imke Hans et al.
Imke Hans et al.

Viewed

Total article views: 201 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
153 46 2 201 1 1

Views and downloads (calculated since 24 Aug 2017)

Cumulative views and downloads (calculated since 24 Aug 2017)

Viewed (geographical distribution)

Total article views: 201 (including HTML, PDF, and XML)

Thereof 199 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 24 Nov 2017
Publications Copernicus
Download
Share