TITLE:
Anticipated Inversion and Visibility Conditions over Glacier Bay with a Changing Climate
AUTHORS:
Nicole Mölders, Scott Gende
KEYWORDS:
Glacier Bay National Park, Inversions, Visibility, CESM, WRF/Chem, Downscaling
JOURNAL NAME:
Journal of Environmental Protection,
Vol.6 No.5,
May
22,
2015
ABSTRACT: A RCP4.5
simulation from the Community Earth System Model was downscaled by the Weather
Research and Forecasting Model, inline coupled with chemistry, to examine how
climate change may affect inversions and visibility in Glacier Bay in the
presence of cruise-ship visitations. Mean downscaled climate conditions for the
tourist seasons for 2006-2012 were compared with downscaled conditions for
2026-2032 with identical cruise-ship entries and operating conditions thereby
isolating pollutant retention and visibility differences caused by atmospheric
climate change. Notable changes in future temperature, humidity, precipitation,
and wind-speed occurred for large areas of Southeast Alaska and the Gulf of
Alaska, although the anticipated differences were less pronounced in Glacier
Bay due to the presence of the large glaciers and ice fields. While increased
sensible heat and water vapor in the atmospheric boundary layer contributed to
on average 4.5 h reduced inversion duration in Glacier Bay, the on average 0.23
m·s-1 reduced wind speeds increased inversion frequency by 4% on
average. The future on average wetter conditions and altered precipitation
patterns in Glacier Bay affected the removal of gases and particulate matter
emitted by cruise ships locally or advected from areas outside the park. Season-spatial
averaged visibility in Glacier Bay remained the same. However, visibility was
degraded in the future scenario later in the season and slightly improved
during spring. The warmer conditions contributed to decreased visibility
indirectly by tieing up less NO2 in PAN and increasing biogenic NOx emissions. The wetter conditions contributed to reduced visibility in the last
third of the tourist season.