Journal Article

Greenland Ice Sheet Mass Balance Reconstruction. Part II

Box, Jason E.

2013

Overview

Meteorological station records, ice cores, and regional climate model output are combined to develop a continuous 171-yr (1840–2010) reconstruction of Greenland ice sheet climatic surface mass balance (Bclim) and its subcomponents including near-surface air temperature (SAT) since the end of the Little Ice Age. Independent observations are used to assess and compensate errors. Melt water production is computed using separate degree-day factors for snow and bare ice surfaces. A simple meltwater retention scheme yields the time variation of internal accumulation, runoff, and bare ice area. At decadal time scales over the 1840–2010 time span, summer (June–August) SAT increased by 1.64°C, driving a 59% surface meltwater production increase. Winter warming was +2.0°C. Substantial interdecadal variability linked with episodic volcanism and atmospheric circulation anomalies is also evident. Increasing accumulation and melt rates, bare ice area, and meltwater retention are driven by increasing SAT. As a consequence of increasing accumulation and melt rates, calculated meltwater retention by firn increased 51% over the period, nearly compensating a 63% runoff increase. Calculated ice sheet end of melt season bare ice area increased more than 5%. Multiple regression of interannual SAT and precipitation anomalies suggests a dominance of melting on Bclimand a positive SAT precipitation sensitivity (+32 Gt yr−1K−1or 6.8% K−1). The Bclimcomponent magnitudes from this study are compared with results from Hanna et al. Periods of shared interannual variability are evident. However, the long-term trend in accumulation differs in sign.

• Publisher: American Meteorological Society
• Subject: Ablation / Accumulation / Air temperature / Anomalies / Atmospheric circulation / Atmospheric circulation anomalies / Bare ice / Climate models / Cores / Correlations / Dominance / Earth, ocean, space / Equilibrium / Exact sciences and technology / External geophysics / Firn / Glaciation / Global warming / Greenland ice sheet / Ice / Ice ages / Ice cores / Ice sheets / Interannual variability / Interdecadal variability / Little Ice Age / Mass / Mass balance / Mass balance of ice sheets / Mathematical analysis / Mathematical models / Melting / Melts / Meltwater / Precipitation / Precipitation anomalies / Rain / Reconstruction / Regional climate models / Regional climates / Regional development / Retention / Runoff / Runoff increase / Sea level / Seasons / Snow / Snow. Ice. Glaciers / Studies / Surface temperature / Surface water / Surface-air temperature relationships / Temperature / Trends / Variability / Volcanic activity / Volcanism / Weather stations