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Water vapor mixing ratios profiled in Finland by means of a lidar, a satellite and a model

Water vapor mixing ratios profiled in Finland by means of a lidar, a satellite and a model

As the dominant greenhouse gas, water vapour is involved in most of the atmospheric processes accounting for about half of today's greenhouse effect. Seasonal analysis of water vapor was done in Kuopio.

Tropospheric water vapor profiles were measured with a Raman lidar during three field campaigns held in Finland. Co-located radio soundings were available throughout the period for the calibration of the lidar signals. "We investigated the possibility of calibrating the lidar water vapor profiles in the absence of co-existing on site soundings using water vapor profiles from the combined Advanced Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU) satellite product; the Aire Limitee Adaptation dynamique Development International and High Resolution Limited Area Model (ALADIN/HIRLAM) numerical weather prediction (NWP) system, and the nearest radio sounding station located 100 km away from the lidar site (only for the permanent location of the lidar)", says researcher Maria Filioglou.  

The uncertainties of the calibration factor derived from the soundings, the satellite and the model data are < 2.8 %, 7.4 % and 3.9 %, respectively. Water vapor mixing ratio intercomparisons between the radio soundings and the various instruments/model for the period of the campaigns are also available.  A good agreement is observed for all comparisons with relative errors that do not exceed 50 % up to 8 km altitude in most cases.

Seasonal analysis of water vapor was done in Kuopio

A four-year seasonal analysis of vertical water vapor is also presented for the Kuopio site in Finland. During winter months, the air in Kuopio is dry (1.15 ± 0.40 g kg−1); during summer it is wet (5.54 ± 1.02 g kg−1); and at other times, the air is in an intermediate state. These are averaged values over the lowest 2 km in the atmosphere. Above that height a quick decrease of water vapor mixing ratios is observed, except during summer months where favorable atmospheric conditions enable higher mixing ratio values at higher altitudes. Lastly, the seasonal change in disagreement between the lidar and the model has been studied. The analysis showed that, on average, the model underestimates water vapor mixing ratios at high altitudes during spring and summer.

More information:

Maria Filioglou, tel. +358 50 463 9930, maria.filioglou@fmi.fi

Filioglou, M., Nikandrova, A., Niemelä, S., Baars, H., Mielonen, T., Leskinen, A., Brus, D., Romakkaniemi, S., Giannakaki, E., and Komppula, M.: Profiling water vapor mixing ratios in Finland by means of a Raman lidar, a satellite and a model, Atmos. Meas. Tech., 10, 4303-4316, https://doi.org/10.5194/amt-10-4303-2017, 2017.


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