Assessment of the total precipitable water from a sun photometer, microwave radiometer and radiosondes at a continental site in southeastern Europe
In this study, we discuss the differences in the total precipitable water (TPW), retrieved from a Cimel sun photometer operating at a continental site in southeast Europe, between version 3 (V3) and version 2 (V2) of the AErosol RObotic NETwork (AERONET) algorithms. In addition, we evaluate the perf...
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Published in | Atmospheric measurement techniques Vol. 12; no. 3; pp. 1979 - 1997 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
29.03.2019
Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | In this study, we discuss the differences in the total precipitable water
(TPW), retrieved from a Cimel sun photometer operating at a continental site
in southeast Europe, between version 3 (V3) and version 2 (V2) of the
AErosol RObotic NETwork (AERONET) algorithms. In addition, we evaluate the
performance of the two algorithms comparing their product with the TPW
obtained from a collocated microwave radiometer and nearby radiosondes during
the period 2007–2017. The TPW from all three instruments was highly
correlated, showing the same annual cycle, with lower values during winter
and higher values during summer. The sun photometer and the microwave radiometer
depict the same daily cycle, with some discrepancies during early morning and
late afternoon due to the effect of solar zenith angle on the measurements of
the photometer. The TPW from V3 of the AERONET algorithm has small
differences compared with V2, mostly related to the use of the new
laboratory-based temperature coefficients used in V3. The microwave
radiometer measurements are in good agreement with those obtained by the
radiosonde, especially during night-time when the differences between the two
instruments are almost negligible. The comparison of the sun photometer data
with high-quality independent measurements from radiosondes and the radiometer
shows that the absolute differences between V3 and the other two datasets are
slightly higher compared with V2. However, V3 has a lower dependence from the
TPW and the internal sensor temperature, indicating a better performance of
the retrieving algorithm. The calculated one-sigma uncertainty for V3 as
estimated, from the comparison with the radiosondes, is about 10 %, which is
in accordance with previous studies for the estimation of uncertainty for V2.
This uncertainty is further reduced to about 6 % when AERONET V3 is
compared with the collocated microwave radiometer. To our knowledge, this is
the first in-depth analysis of the V3 TPW, and although the findings presented
here are for a specific site, we believe that they are representative of
other mid-latitude continental stations. |
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ISSN: | 1867-8548 1867-1381 1867-8548 |
DOI: | 10.5194/amt-12-1979-2019 |