Ice velocity and mass balance measurements at Hurd glacier

In English:
The main activities were mass balance and ice velocity measurements in the net
of stakes of Hurd glacier, complemented by the maintenance of the net of stakes
of Johnsons glacier, plus some radar profiles in the side lobes of Hurd
glacier.

The ice velocities at surface were determined by repeated DGPS positioning of
the stakes of Hurd (some 30 stakes) and Johnsons (some 20 stakes). Two full
sets of measurements were done, one at the beginning and another one close to
the end of the campaign. The maintenance of the stake network consisted of
extending those stakes in the accumulation area close to be buried by the snow,
as well as re-inserting, at a deeper level, those stakes in the ablation area
having only a small portion below the ice surface, so being at risk of falling.
For re-inserting the latter, a steam drill was used.

A radio-echo sounding of the side lobes of Hurd glacier was performed, aimed at
complementing those done during the previous campaign. Several profiles were
done, using an ice-penetrating radar VIRL-2A (central frequency 15-18 MHz), on
the side lobes of Hurd glacier draining toward False Bay (Argentina and Las
Palmas lobes). Transmitter and receiver, with their corresponding antennae and
the digital recording system, were placed on two sledges towed by snowmobiles.

En Espanol:
Las actividades desarrolladas estuvieron centradas en la realizacion de medidas
de balance de masas y de velocidad del hielo en la superficie del glaciar Hurd,
complementados con el mantenimiento de la red de estacas del glaciar Johnsons y
la realizacion de perfiles adicionales de radioecosonda en los lobulos
laterales del glaciar Hurd.

Las medidas de velocidades superficiales del hielo se obtuvieron a partir de
los datos de posicionamiento preciso de las redes de estacas de los glaciares
Hurd y Johnsons en periodos sucesivos (una treintena y una veintena de estacas,
respectivamente). Se efectuaron dos tandas completas de medidas, una al inicio
de la campana y otra al final de la misma. Se realizo el mantenimiento de las
redes de estacas: extender las que, en zona de acumulacion, estan a punto de
quedar sepultadas, y reinstalar a mayor profundidad, en zona de ablacion,
aquellas cuya parte expuesta es grande, por lo que podrian llegar a caer. Esta
ultima operacion requiere el uso de sonda de vapor.

Se llevo a cabo un radioecosondeo de los lobulos laterales del glaciar Hurd con
objeto de complementar los efectuados durante la anterior campana. Se
realizaron perfiles con radioecosonda VIRL-2A (frecuencia central 15-18 MHz) en
los lobulos laterales del glaciar Hurd que drenan hacia Bahia Sur (lobulos
Argentina y Las Palmas). Los equipos emisor y receptor, con sus antenas
correspondientes y con el sistema de registro digital asociado, se instalaron
en sendos trineos arrastrados por motos de nieve.