Reconstruction of the mean specific mass balance of vatnajökull (iceland) with a seasonal sensitivity characteristic

Abstract

We present a Seasonal Sensitivity Characteristic (SSC) of Vatnajökull (Iceland), which consists of the sensitivity of the mean specific mass balance to monthly perturbations in temperature and precipitation. The climate in Iceland is predominantly maritime (high precipitation) although often the polar air mass influences the area. This results in temperature sensitivities that are high in summer and nearly zero during the winter months. In contrast, precipitation sensitivities are high in winter and low in summer. We use the SSC of Vatnajökull as a reduced mass balance model, with which we reconstruct the mass balance of Vatnajökull since 1825. The reduced model shows that changes in temperature and precipitation like the ones observed both have a significant impact upon the mass balance. The reconstructed mass balance records for two Icelandic glaciers correlate very well with mass balance records that are extracted from length records with a linear inverse model. This places confidence in both the reduced (forward) mass balance model and in the inverse model, although the forward method produces larger mass balance variations than the inverse method. For the south of Vatnajökull we find that after 1900, the length record is well explained by temperature variations alone, while another Icelandic glacier (Sólheimajökull) was also influenced by precipitation variations.

Origin and de‐icing of multiple generations of ice‐cored moraines at Brúarjökull, Iceland

“…For 1964Á1988, the MAAT in Kringilsárrani was more than 0.58C colder than the two surrounding periods. The reduced dead-ice melting rate from the period 1964Á1988 is in agreement with results from de Ruyter de Wildt et al (2003), who reported a local 9. A.…”

“…For 1964Á1988, the MAAT in Kringilsárrani was more than 0.58C colder than the two surrounding periods. The reduced dead-ice melting rate from the period 1964Á1988 is in agreement with results from de Ruyter de Wildt et al (2003), who reported a local Temperatures from Kringilsárrani were correlated (R 2 00.99) on a monthly basis for 2003Á2005 with meteorological data from Kárahnjú kar (25 km north of Brú arjö kull) dating back to 1999. Subsequently, the composite temperature series for 1999Á2005 was correlated on a monthly basis with meteorological data from Brú á Jö kuldal (40 km north of Brú arjö kull) for 1969Á2005, with R 2 00.99.…”

“…The equation from the last regression analysis allowed calculation of the mean monthly temperature in Kringilsárrani for 1830Á1968 and, subsequently, calculation of annual temperatures. Extrapolating monthly and annual temperatures back in time is possible because of the strong correlation between mean air temperatures from east and west Iceland (de Ruyter de Wildt et al 2003;Ravn 2006). B.…”

Firn layer impact on glacial runoff: a case study at Hofsjökull, Iceland

“…Hence, even small temperature increases in summer may have a considerable effect on mass balance and glacial runoff. The seasonal mass balance characteristic found on Hofsjökull is typical of maritime climates and similar to results obtained on Vatnajökull (de Ruyter de Wildt et al, 2003). Sensitivities have been shown to be higher on maritime glaciers characterized by high precipitation and large mass turnover compared with glaciers in continental environments (e.g.…”

Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012

“…The climate is largely a result of local (boundary layer) controls upon the weather. Vatnajökull probably determines the prevailing wind direction (southwesterly) within the central highlands and promotes a high pressure field and strong katabatic winds (Ashwell, 1986;de Ruyter de Wildt et al, 2003;Arnalds et al, 2011). The Ódáðahraun is a vast expanse of basalt sand that is a semidesert characterised by an almost total lack of vegetation or well-developed soil cover, vast lava flows, deflated bedrock forms, ventifacted bedrock surfaces and large boulders, mixed-genesis gravel sheets, dunes and bars, and aeolian sand (Käyhkö et al, 2002;Alho, 2003;Arnalds et al, 2011).…”