Tropospheric water vapor from solar spectrometry and comparison with Jason microwave radiometer measurements

Abstract

[1] Atmospheric water vapor is a crucial factor in achieving highest accuracies in the field of space geodesy, particularly in the determination of height. A new instrumental approach to high-precision determination of tropospheric water vapor has been investigated and realized in the construction of a mobile solar spectrometer. The optical approach as applied to the spectrometer allows the simultaneous measurement of single vibrational-rotational absorption lines in the wide wavelength range between 728 nm and 915 nm. Dedicated field experiments have been carried out in the frame of an EU project for calibrating the Jason onboard microwave radiometer. A comparison of the spectrometer results with a conventional ground-based water vapor radiometer and radiosondes revealed a fit on the order of 10 mm for the wet path delay, which corresponds to 1.6 kg/m 2 integrated water vapor content (IWV). The comparison with the measurements from the radiometer of Jason reveals an even better agreement for the wet path delay. Long time series are foreseen for a detailed statistical analysis. The mobile solar spectrometer can be considered as a novel portable tool for determining tropospheric water vapor and as an excellent space-borne radiometer calibration and validation system.

Fifteen Years of Cal/Val Service to Reference Altimetry Missions: Calibration of Satellite Altimetry at the Permanent Facilities in Gavdos and Crete, Greece

“…From 11 January to 11 January 2003, a GEMOSS-I radiometer campaign was conducted in Rethymnon, Crete, to measure the zenith wet path delay during the overflight of Jason-1 on 11 January 2003 ( Figure 17). In the past, a Geodetic Mobile Solar Spectrometer (GEMOSS-I), developed by ETH Zurich, Switzerland, was used at the PFAC to retrieve the precipitable water vapor content in the atmosphere [39] during a satellite altimeter pass. From 11 January to 11 January 2003, a GEMOSS-I radiometer campaign was conducted in Rethymnon, Crete, to measure the zenith wet path delay during the overflight of Jason-1 on 11 January 2003 ( Figure 17).…”

Characterisation and Field Test of a Simple AvaSpec Array Spectroradiometer for Solar Irradiance Measurements at an Alpine Site

“…Further details on the application of spectroradiometers to PV technology are provided in Section S1 of the Supplementary Materials. Array spectroradiometers are also adopted in studies about air quality, photochemistry and atmospheric composition [12][13][14][15][16][17][18][19][20][21], by taking advantage of the spectral signature of some light-absorbing atmospheric compounds; phototherapy and medical dosimetry [22,23], in which the observation of the radiation spectrum is essential for assessing wavelengthdependent biological effects; measurement of the Earth's surface reflectance, e.g., to identify snow impurities [24]; and the monitoring of water quality and ecosystems [25][26][27]. Finally, array systems are not only useful in research but may also be introduced in industrial applications where reference solar spectra are required [28] or where spectroscopy-based techniques are employed for process control [29].…”

Calibration and Evaluation of Precipitable Water Vapor From MODIS Infrared Observations at Night

“…Spaceborne monitoring is strictly the only effective technique to evaluate water vapor distribution on a global scale. Currently, a number of sensors onboard satellite platforms have been implemented to observe water vapor amount, such as the Moderate Resolution Imaging Spectroradiometer (MODIS) [9] on Terra and Aqua platforms, the Medium Resolution Imaging Spectrometer (MERIS) [10] on Environmental Satellite platform, the Atmospheric Infrared Sounder (AIRS) [11] onboard Aqua, the Infrared Atmospheric Sounding Interferometer [12] onboard MetOp, the Microwave Radiometers (MWR) [13] onboard TOPEX/Poseidon and Jason, the Tropical Rainfall Measuring Mission's Microwave Imager (TMI) [14], and the recently launched Global Precipitation Measurement Microwave Imager [14]. The space-based instruments that detect infrared (IR) or (and) near-infrared (nIR) frequencies can measure moisture over both land and ocean regions, but only information collected under cloud-free conditions can be used, as the IR and nIR measurements are sensitive to the presence of clouds in the field of view.…”