Radiometer data from the high-Arctic ASCOS expedition 2008

Ola Persson

High resolution (in time and space) vertical profiles of temperature were obtained from a 60GHz scanning microwave radiometer. The radiometer measures the brightness temperature along the line-of-sight and generates a vertical profile by scanning in the vertical plane. The vertical resolution and accuracy decreases with altitude up to the measuring top at 1.2 km. It was located on the starboard bridge-roof wing of the Icebreaker Oden with a free view to starboard. The retrieval from this instrument uses the radiosonde profiles as a first guess and thus adds information on vertical and temporal variability to the radiosonde profiles.

Citation

Ola Persson (2018) Radiometer data from the high-Arctic ASCOS expedition 2008. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-ascos-2008-radiometer-1

References

Tjernström, M. et al. 2014. The Arctic Summer Cloud Ocean Study (ASCOS): overview and experimental design. Atmospheric Chemistry and Physics, 14, 2823–2869. https://doi.org/10.5194/acp-14-2823-2014

Data description

Update Version v1a, 9/3/09 OP

File ASCOS_60GHz_data_6h_v1a.mat replaces ASCOS_60GHz_data_6h_v1.mat because of some minor timing and low-level errors found in latter. File ASCOS_60GHz_data_6h_v1a.mat contains the 60 GHz scanning radiometer temperature profiles in matlab format. Only the scans from the right-hand-side of the ship are used (over the ice); those from the left-hand-side (over the bow) are not used. The retrieval technique follows Trokhimovski et al 1998 (IEEE Trans) and others and uses a linear interpolation of the 6-hourly soundings as a first guess. In the linear retrieval, a value of gamma=.05 is used. This is a compromise value to allow deviations from the first guess but to minimize the amount of spurious superadiabatic lapse rates obtained at low levels. Validations against independent sondes show root-mean-square-errors typically less than 1.0 K. Future versions of this data set will try to allow greater deviations by applying additional numerical constraints on the retrieval. Additional information can be found in the tables in the readme file.

The parameters include
JDayTot(1x9721) – the Year day of the retrieved soundings
sond6Time(1x10150) – the year day of the interpolated soundings
TeProTot6_05n(80x9721) – the 60GHz radiometer temperatures
h2(1x80) – height field
sond6Tem(80x10150) – sounding temperatures

A netcdf file of this same data is also in this zip file – the latitude and longitude are also included in the netcdf file

Comments

High resolution (in time and space) vertical profiles of temperature were obtained from a 60GHz scanning microwave radiometer. The radiometer measures the brightness temperature over an averaged window along the line-of-sight and by scanning in the vertical plane it provides this information at decreasingly high vertical resolution and accuracy with altitude up to 1.2 km. It was located on the starboard bridge-roof wing with a free view to starboard. The retrieval is based on a first-guess that comes from interpolation of radiosonde profiles; hence, this instrument adds information on vertical and temporal variability to the radiosonde profiles. At higher altitudes, it converges against the interpolated soundings and variability decreases while at lower altitudes it is consistent with the soundings in an average sense.

Original address: http://www.ascos.se/index.php?q=node/283

Files:
ASCOS_60Ghz_radiometer_data_v1a.ZIP (14 MB)