Recent changes of relative humidity: regional connections with land and ocean processes
<p>We analyzed changes in surface relative humidity (RH) at the global scale from 1979 to 2014 using both observations and the ERA-Interim dataset. We compared the variability and trends in RH with those of land evapotranspiration and ocean evaporation in moisture source areas across a ran...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Earth System Dynamics |
| Online Access: | https://www.earth-syst-dynam.net/9/915/2018/esd-9-915-2018.pdf |
| Summary: | <p>We analyzed changes in surface relative humidity (RH) at the global scale
from 1979 to 2014 using both observations and the ERA-Interim dataset. We
compared the variability and trends in RH with those of land
evapotranspiration and ocean evaporation in moisture source areas across a
range of selected regions worldwide. The sources of moisture for each
particular region were identified by integrating different observational data
and model outputs into a Lagrangian approach. The aim was to account for the
possible role of changes in air temperature over land, in comparison to sea
surface temperature (SST), but also the role of land evapotranspiration and
the ocean evaporation on RH variability. The results demonstrate that the
patterns of the observed trends in RH at the global scale cannot be linked to
a particular individual physical mechanism. Our results also stress that the
different hypotheses that may explain the decrease in RH under a global
warming scenario could act together to explain recent RH trends. Albeit with
uncertainty in establishing a direct causality between RH trends and the
different empirical moisture sources, we found that the observed decrease in
RH in some regions can be linked to lower water supply from land
evapotranspiration. In contrast, the empirical relationships also suggest
that RH trends in other target regions are mainly explained by the dynamic
and thermodynamic mechanisms related to the moisture supply from the oceanic
source regions. Overall, while this work gives insights into the connections
between RH trends and oceanic and continental processes at the global scale,
further investigation is still desired to assess the contribution of both
dynamic and thermodynamic factors to the evolution of RH over continental
regions.</p> |
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| ISSN: | 2190-4979 2190-4987 |