TY - JOUR
T1 - Long-term surface energy balance of the western Greenland Ice Sheet and the role of large-scale circulation variability
AU - Huai, B.
AU - van den Broeke, M. R.
AU - Reijmer, C. H.
PY - 2020/11/25
Y1 - 2020/11/25
N2 - We present the surface energy balance (SEB)
of the western Greenland Ice Sheet (GrIS) using an energy balance model forced with hourly observations from
nine automatic weather stations (AWSs) along two transects: the Kangerlussuaq (K) transect with seven AWSs in
the southwest and the Thule (T) transect with two AWSs in
the northwest. Modeled and observed surface temperatures
for non-melting conditions agree well with RMSEs of 1.1–
1.6 K, while reasonable agreement is found between modeled and observed 10 d cumulative ice melt. Absorbed shortwave radiation (Snet) is the main energy source for melting (M), followed by the sensible heat flux (Qh). The multiyear average seasonal cycle of SEB components shows
that Snet and M peak in July at all AWSs. The turbulent
fluxes of sensible (Qh) and latent heat (Ql) decrease significantly with elevation, and the latter becomes negative at
higher elevations, partly offsetting Qh. Average June, July
and August (JJA) albedo values are < 0.6 for stations below 1000 m a.s.l. and > 0.7 for the higher stations. The nearsurface climate variables and surface energy fluxes from reanalysis products ERA-Interim, ERA5 and the regional climate model RACMO2.3 were compared to the AWS values.
The newer ERA5 product only significantly improves ERAInterim for albedo. The regional model RACMO2.3, which
has higher resolution (5.5 km) and a dedicated snow/ice module, unsurprisingly outperforms the reanalyses for (near-
)surface climate variables, but the reanalyses are indispensable in detecting dependencies of west Greenland climate
and melt on large-scale circulation variability. We correlate
ERA5 with the AWS data to show a significant positive correlation of western GrIS summer surface temperature and
melt with the Greenland Blocking Index (GBI) and weaker
and opposite correlations with the North Atlantic Oscillation
(NAO). This analysis may further help to explain melting patterns on the western GrIS from the perspective of circulation anomalies.
AB - We present the surface energy balance (SEB)
of the western Greenland Ice Sheet (GrIS) using an energy balance model forced with hourly observations from
nine automatic weather stations (AWSs) along two transects: the Kangerlussuaq (K) transect with seven AWSs in
the southwest and the Thule (T) transect with two AWSs in
the northwest. Modeled and observed surface temperatures
for non-melting conditions agree well with RMSEs of 1.1–
1.6 K, while reasonable agreement is found between modeled and observed 10 d cumulative ice melt. Absorbed shortwave radiation (Snet) is the main energy source for melting (M), followed by the sensible heat flux (Qh). The multiyear average seasonal cycle of SEB components shows
that Snet and M peak in July at all AWSs. The turbulent
fluxes of sensible (Qh) and latent heat (Ql) decrease significantly with elevation, and the latter becomes negative at
higher elevations, partly offsetting Qh. Average June, July
and August (JJA) albedo values are < 0.6 for stations below 1000 m a.s.l. and > 0.7 for the higher stations. The nearsurface climate variables and surface energy fluxes from reanalysis products ERA-Interim, ERA5 and the regional climate model RACMO2.3 were compared to the AWS values.
The newer ERA5 product only significantly improves ERAInterim for albedo. The regional model RACMO2.3, which
has higher resolution (5.5 km) and a dedicated snow/ice module, unsurprisingly outperforms the reanalyses for (near-
)surface climate variables, but the reanalyses are indispensable in detecting dependencies of west Greenland climate
and melt on large-scale circulation variability. We correlate
ERA5 with the AWS data to show a significant positive correlation of western GrIS summer surface temperature and
melt with the Greenland Blocking Index (GBI) and weaker
and opposite correlations with the North Atlantic Oscillation
(NAO). This analysis may further help to explain melting patterns on the western GrIS from the perspective of circulation anomalies.
U2 - 10.5194/tc-14-4181-2020
DO - 10.5194/tc-14-4181-2020
M3 - Article
SN - 1994-0424
VL - 14
SP - 4181
EP - 4199
JO - The Cryosphere
JF - The Cryosphere
IS - 11
ER -
