FR3092669A1 - Device and method for measuring the surface melting of a glacier - Google Patents

Abstract

Device and method for measuring the surface melting of a glacier. The invention relates to the field of glaciology and more particularly to a device 1 for measuring the surface melt of a glacier comprising: a module for measuring the surface melt of the glacier; - a remote transmission system; - a support ; and- a battery; characterized in that the measuring module comprises a cable 110, a reel suitable for winding the cable 110 so as to keep said cable in tension, an encoder wheel configured so as to be driven in rotation during a winding of the cable by the reel; the reel and the encoder wheel being arranged so that the melting surface of the glacier induces the winding of the cable by the reel and a corresponding rotation of the encoder wheel; the teletransmission system therefore being able to emit a measurement signal proportional to the melting of the glacier's surface. Figure for the abstract: Fig. 1

Description

Device and method for measuring the melting on the surface of a glacier

The invention relates to the field of glaciology. It finds a particularly advantageous application in the measurement of melting on the surface of a glacier.

The measurement of the surface melting of a glacier is historically carried out using beacons comprising a succession of stakes, generally 2 meters long, linked to each other by a chain. Using a steam probe or a drill, holes are drilled in the ice or snow on the surface of a glacier, to a depth roughly equal to the length of the stakes. The beacon stakes are then inserted into the drilled holes. With this method, the melting of snow and/or ice on the surface of the glacier is quantified by manual measurement of the emergence of beacons over time. This measurement is carried out by an operator going to the field, generally at a monthly frequency during the melting period, generally from June to October in the northern hemisphere.

Measurement by beacon is discontinuous in time and requires travel in the field. Consequently, the surface melting of the glacier is integrated into the time interval separating two successive visits, which does not allow access to the variability of the melting on a short time scale, for example per hour, per day or per week. In addition, if we consider a surface melting of the glacier of 10 meters per year in the ablation zone of the glacier, it is necessary to reinstall the beacons several times a year. Thus, in addition to the trips to measure the emergence of the beacons, trips for the reinstallation of the beacons are also to be expected; however, access to beacons for measurement and/or their reinstallation is always difficult and may be made impossible, in particular due to weather conditions, which consequently limits the performance of measurements.

Autonomous devices have been developed in order to obtain a continuous measurement of the surface melting of a glacier. There are in particular devices comprising an ultrasound probe fixed to a mast implanted in the ice or the snowpack. The ultrasound probe is thus theoretically held in a fixed position and emits an ultrasound signal, part of which is reflected by the surface of the glacier, so that the reflected signal is detected by the probe and provides information on the distance between the probe and the surface. of the glacier. When melting occurs, the distance from the probe to the surface of the glacier increases, allowing the surface melting of the glacier to be measured.

Alternatively, a device known from the state of the art comprises an ultrasound source and a detector, one being buried under the surface of the glacier while the other is fixed to the emerged end of a mast planted in ice or snow cover. The ultrasonic signal emitted by the source thus crosses a portion of ice or snow before being collected by the detector. The portion of ice or snow crossed modifies the detected signal, thus making it possible to quantify the accumulation or the melting of ice or snow. It is more particularly known, from document JPH07113877, of a device comprising an oscillating source coupled to a detector, said device being suitable for measuring the variation in thickness of the snowpack to calculate the water equivalent of the available snow.

Autonomous devices according to the characteristics described above have several drawbacks. In particular, during the melting of the surface of the glacier, the masts on which said devices are fixed gradually emerge. Because of this increasing emergence, their position can vary, for example by a progressive inclination of the mast or even can completely fall. This decreases, on the one hand, the reliability of the measurement and, on the other hand, may require frequent, potentially monthly, reinstallation of the devices. Their autonomy is therefore quite relative.

Current devices and methods for measuring melting on the surface of a glacier therefore have their limits. In particular, none of them allows continuous measurement of the surface melting of a glacier while minimizing the movements of an operator in the field.

In this context, the present invention proposes, according to a first aspect, a device making it possible to overcome at least one of the aforementioned drawbacks.

More particularly, the device according to the first aspect of the invention aims to allow continuous, precise and reliable measurement over a long period, potentially over at least a year, of the melting at the surface of a glacier, while limiting the need to send an operator to the field.

The other objects, features and advantages of the present invention will become apparent from a review of the following description and the accompanying drawings. It is understood that other benefits may be incorporated.

To achieve this objective, according to one embodiment, the present invention provides a device for measuring the melting on the surface of a glacier comprising a module for measuring the melting on the surface of the glacier, an acquisition unit capable of controlling the module module and to receive a measurement signal from the measurement module, a remote transmission system for the measurement signal transmitted from the measurement module by the acquisition unit, a support configured to support at least part of the measurement module, and a battery capable of powering at least the measurement module, the acquisition unit and the remote transmission system.

The measurement module comprises a cable of which a first portion, or even a first end, is intended to be anchored in a hole drilled in the glacier, as well as a reel capable of winding the cable by a second portion , or even a second end , of the cable, so as to keep the cable under tension between said first and second portions , or even between its two ends. The measurement module further comprises an encoder wheel configured fixedly relative to the winder and so as to accommodate, along at least part of its circumference, a third portion of the cable located between said first and second portions , or even between the two ends of the cable, so that the encoder wheel is driven in rotation during winding of the cable by the reel; the reel and the encoder wheel being arranged substantially plumb with the hole drilled using the support placed on the glacier, so that the melting on the surface of the glacier induces the winding of the cable by the reel and a rotation corresponding encoder wheel. The remote transmission system is therefore capable of emitting a measurement signal proportional to the melting of the surface of the glacier.

The device as introduced above is placed on the surface of the glacier. Thus, the distance between the surface of the glacier and the whole formed by the reel and the encoder wheel does not change over time, it is the progressive winding of the cable which is measured by the encoder wheel to assess the surface melting of the glacier. The measurement of the melting on the surface of the glacier can thus be carried out continuously. This also has several advantages. First, the stability of the device is maintained during the melting of the glacier surface. Once installed, the device is therefore operational for a long time, potentially for at least a year, without requiring frequent interventions by an operator having to go to the installation site. The reliability of the melting measurements on the surface of the glacier acquired over this period is also maintained. Secondly, the use of a measurement module comprising a winder and an encoder wheel according to the invention confers precision of the order of a millimeter on the measurement, while limiting the cost of the device, in particular compared to a device comprising an ultrasound source and the appropriate detector.

• le module de mesure peut comprendre au moins un capteur propre à mesurer au moins une condition environnementale du dispositif, notamment la température, la force du vent, l’ensoleillement et/ou la hauteur de neige ;
• le module de mesure peut comprendre au moins un capteur, tel qu’un inclinomètre ou un capteur GPS, propre à mesurer au moins une condition de fonctionnement du dispositif, telle que l’inclinaison ou la position du dispositif ;
• la centrale d’acquisition peut être propre à stocker des signaux de mesure issus du module de mesure ;
• l’enrouleur peut être un enrouleur à rappel automatique, comprenant préférentiellement un ressort à lame ;
• le dispositif peut comprendre en outre un lest fixé au câble pour ancrer la première portion, voire la première extrémité, du câble dans le trou foré, le lest étant préférentiellement initialement déposé en appui au fond du trou foré. L ’ utilisation d’un lest déposé au fond du trou foré permet de bénéficier d’une capacité de mesure de la fonte en surface du glacier égale à la profondeur du trou foré. Elle combine potentiellement les avantages précédemment énoncés et est compatible avec les caractéristiques suivantes du dispositif ;
• le câble peut être réalisé en un matériau synthétique, préférentiellement en polyamide, préférentiellement en nylon. L’utilisation d’un matériau synthétique, tel que le polyamide et plus particulièrement le nylon, permet avantageusement, d’une part, de limiter le coût et le poids du dispositif, et d’autre part, de résister aux conditions météorologiques observables sur un glacier ;
• la longueur initiale du câble entre lesdites première et troisième portions peut être d’une longueur comprise entre 5 et 20 mètres, préférentiellement entre 8 et 15 mètres. La mesure est ainsi réalisée sur une grande plage en longueur, permettant ainsi de mesurer la fonte en surface du glacier pour de fortes amplitudes de fonte ou d’effectuer la mesure sur une durée étendue, préférentiellement sur un an ;
• le câble peut être de section circulaire, permettant ainsi de limiter sa prise au vent, notamment sur une éventuelle portion émergée, située entre la surface du glacier et le module de mesure, susceptible d’être exposée aux intempéries. La fiabilité de la mesure est ainsi améliorée ;
• le dispositif peut comprendre en outre un module de recharge de la batterie, plus particulièrement un panneau photovoltaïque.

Optionally, the invention may also have at least one of the following characteristics:

• the measurement module can comprise at least one sensor capable of measuring at least one environmental condition of the device, in particular the temperature, the force of the wind, the sunshine and/or the depth of snow;
• the measurement module can comprise at least one sensor, such as an inclinometer or a GPS sensor, capable of measuring at least one operating condition of the device, such as the inclination or the position of the device;
• the acquisition unit can be suitable for storing measurement signals from the measurement module;
• the retractor may be a self-retracting retractor, preferably comprising a leaf spring;
• the device may further comprise a ballast fixed to the cable to anchor the first portion, or even the first end, of the cable in the drilled hole, the ballast being preferably initially deposited in support at the bottom of the drilled hole. The use of a ballast placed at the bottom of the drilled hole makes it possible to benefit from a capacity for measuring the melting on the surface of the glacier equal to the depth of the drilled hole. It potentially combines the advantages stated above and is compatible with the following characteristics of the device;
• the cable can be made of a synthetic material, preferably of polyamide, preferably of nylon. The use of a synthetic material, such as polyamide and more particularly nylon, advantageously makes it possible, on the one hand, to limit the cost and the weight of the device, and on the other hand, to resist the weather conditions observable on a glacier ;
• the initial length of the cable between said first and third portions can be between 5 and 20 meters long, preferably between 8 and 15 meters. The measurement is thus carried out over a large range in length, thus making it possible to measure the melting at the surface of the glacier for high amplitudes of melting or to carry out the measurement over an extended period, preferably over one year;
• the cable can be of circular section, thus making it possible to limit its wind resistance, in particular on a possible emerged portion, located between the surface of the glacier and the measurement module, likely to be exposed to bad weather. The reliability of the measurement is thus improved;
• the device may further comprise a battery charging module, more particularly a photovoltaic panel.

• un enroulement progressif du câble par l’enrouleur au fur et à mesure que la surface du glacier fond, entraînant un déplacement de la troisième portion de câble en contact avec la roue codeuse ;
• une rotation de la roue codeuse induite par l’enroulement du câble ;
• une mesure du degré de rotation de la roue codeuse ;
• une conversion de la mesure du degré de rotation en une mesure de hauteur de fonte ;
• la transmission, par le système de télétransmission, des mesures prises, à destination d’un système récepteur, tel qu’un serveur, préférentiellement via le réseau GSM.

According to a second aspect, the present invention provides a method for measuring the melting at the surface of a glacier, using at least one device according to any one of the characteristics stated above, used in combination or alternatively, comprising a step of taking measurements of the melting on the surface of the glacier by the measurement module described above, controlled by the data acquisition unit, said measurements comprising:

• a progressive winding of the cable by the reel as the surface of the glacier melts, causing a displacement of the third portion of cable in contact with the encoder wheel;
• a rotation of the encoder wheel induced by the winding of the cable;
• a measurement of the degree of rotation of the encoder wheel;
• converting the degree of rotation measurement to a cast height measurement;
• the transmission, by the remote transmission system, of the measurements taken, intended for a receiver system, such as a server, preferably via the GSM network.

The method according to the invention has the advantages of the device described above. In addition, the reduced cost of the device as well as the limitation of the interventions of an operator is compatible with the deployment of a plurality of devices to measure at several points of the glacier the melting on the surface of the glacier. Thus, quantification of melting is possible over an extended region, for example on the scale of a glacier.

According to the embodiment in which the measurement module comprises at least one sensor capable of measuring at least one environmental condition of the device, the method further comprises a measurement of said at least one environmental condition. The measurement of at least one environmental condition, in particular the temperature, the force of the wind, the sunshine and/or the depth of snow present on the surface of the glacier, can thus supplement the measurement of the melting on the surface of the glacier, in the aim, for example, of establishing a numerical model of melting on the surface of the glacier.

According to the embodiment in which the measurement module comprises at least one sensor, such as an inclinometer or a GPS sensor, capable of measuring at least one operating condition of the device, the method further comprises a measurement of said at least an operating condition of the device, such as tilt or position of the device. The measurement of said at least one condition makes it possible to ensure the proper functioning of the device independently of the measurement of the melting of the glacier. It is thus possible to more reliably identify a malfunction of the device and consequently to limit, or even avoid, unnecessary movements of an operator.

According to the embodiment in which the acquisition unit is suitable for storing measurement signals from the measurement module, the method comprises, between the steps of taking measurements and transmitting, a step of storage by the acquisition of the measurements taken by the device. In the event that the device does not have access to the GSM network, for example during bad weather, the measurements are thus stored without loss by the data logger. Subsequent transmission is then carried out by the teletransmission system.

Furthermore, according to this particular embodiment, the transmission of the data stored by the acquisition unit is advantageously carried out discontinuously, preferably daily. As an alternative to continuous data transmission, this embodiment reduces the power consumption of the remote transmission system in order to increase the autonomy of the device.

The aims, objects, as well as the characteristics and advantages of the invention will emerge better from the detailed description of an embodiment of the latter which is illustrated by the following accompanying drawings.

illustrates an overview of the device according to one embodiment of the invention.

represents a block diagram of the device according to one embodiment of the invention.

Figures 3A and 3B and illustrate one embodiment of the measurement module

.

illustrates the steps of the method for measuring the melting at the surface of a glacier according to one embodiment of the invention.

The drawings are given by way of examples and do not limit the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily scaled to practical applications. In particular, the relative scales of the elements of the device are not necessarily representative of reality. Furthermore, the respective placements of the elements of the device as described in FIG. 2 are not representative of reality.

During the detailed review of embodiments of the invention, optional features are set forth, which may optionally be used in combination or alternatively.

The device 1 for measuring the melting on the surface of a glacier is intended to be placed on the surface of a glacier, and more particularly on the surface of the ice or of a snowpack, preferentially on the surface of the zone ablation of the glacier. As illustrated in FIG. 1, the device 1 comprises a support 13 configured to stably support at least part of the measurement module 11, and in particular to support the whole formed by the winder and the encoder wheel substantially plumb with a hole drilled into the surface of the glacier. According to particular embodiments, support 13 is configured to support at least part of device 1, preferably device 1 in its entirety. We consider below the embodiment according to which the support 13 supports the device 1 in its entirety. Heavy weather can occur on a glacier, the support 13 is configured to hold and stabilize the device 1, in particular to avoid tilting or deviation of the device 1 from its initial position. More particularly, the support 13 is configured so as to minimize its wind resistance.

The support 13 thus comprises at least two feet 130, preferably three feet, fixed to the body 10 of the device 1 so as to hold it. The feet can comprise at their distal ends bases 131, potentially adjustable, intended to be deposited in contact with the surface of the glacier. The feet 130 can be fixed directly to the body 10 by means of fixing known to those skilled in the art. Said fixing can also be carried out by means of a part, for example circular, enclosing all or part of the body 10, and on which the feet 130 are fixed. The fixing of the feet 130 on the body 10 is preferably carried out at the level of the upper half of the body 10 in order to ensure the stability of the device in the event of bad weather.

Various configurations suitable for allowing the arrangement of the body 10 of the device 1 on the surface of the glacier, by keeping it substantially plumb with a hole drilled in the glacier, can be envisaged by those skilled in the art. For example, the support may comprise two legs 130 terminated by bases 131 configured so as to stabilize the device 1, for example orthogonally to a plane formed by said legs 130. The support may comprise, alternatively, a plurality of feet 130 arranged around the body 10, the angles formed between the feet 130 not necessarily being equal to each other. According to a particular embodiment, the support 13 is a tripod comprising three legs 130, each terminated by a base 131 and fixed in a distributed manner around the body 10, for example at angles of substantially 120° between the legs 130.

The body 10 of the device 1 is configured so as to contain the battery 14, the measurement module 11, the remote transmission system 12, and an acquisition unit 15, while minimizing the wind resistance of the device. It is understood that a shape having one main dimension will be chosen, for example a cylinder or an elongated block, rather than having two main dimensions, such as a panel. The body 10 can be held by the support 13 at a distance from the surface of the glacier or in contact with this surface, or even be partially inserted into the drilled hole. In this last alternative, the device preferably comprises a tube extending the body 10 and configured so as to be partially inserted into the drilled hole.

The body 10 may further comprise openings 16 allowing access to said contained elements. An opening 16 can be formed by a slot in the wall of body 10, closed by a door 160, or a non-solid end of body 10 closed by a cap 161. According to the particular embodiment described in FIG. 1, body 10 of the device 1 comprises a door 160 giving access to the lower part of the body 10, and a cap 161 giving access to its upper part.

The structure of the device 1, comprising the support 13 and the body 10, can be made from a plurality of materials accessible to those skilled in the art, preferably chosen from synthetic materials, composite or not, and metals, preferably stainless steel, the materials being resistant to the meteorological conditions observable on a glacier, and in particular to low temperatures and high humidity. The choice of materials is preferably made so as to limit the weight of the device to facilitate its transport, while aiming to guarantee the stability of the device for the duration of its use, preferably for one year.

As illustrated in FIG. 2, the device comprises a battery 14 capable of powering at least one of the elements included in the device 1, and particularly at least the measurement module 11, the remote transmission system 12 and the acquisition unit 15. In the measurement module 11, the battery 14 more particularly supplies the encoder wheel 112 included in the whole 110, 111,112 formed by the cable 110, the reel 111 and the encoder wheel 112. According to particular embodiments, the measurement module includes sensors 113, 114 which can also be powered by battery 14.

The battery 14 thus allows the autonomous measurement of at least the melting on the surface of the glacier and the transmission of the measurement by the device 1. In order for the device to be operational over an extended period, preferably one year, without moving an operator in the field to replace the battery 14, the device can be provided with a charging module 141 of the battery 14. The charging module 141 is more particularly a photovoltaic panel, arranged for example on the support 13 as described in FIG. 1, and/or directly on the body 10 of the device 1.

The measurements carried out by the device 1 comprise the measurement of the melting at the surface of the glacier, described in more detail later, and according to particular embodiments, the measurement of conditions specific to the device or to its environment. The measurement module 11 can thus comprise at least one sensor 113 able to measure at least one environmental condition of the device 1. The environmental conditions considered are in particular, but not limited to, the temperature, the force of the wind, the sunshine , the height of snow deposited on the surface of the glacier, said surface being for example defined on installation of the device.

The measurement module 11 may further comprise at least one sensor 114 capable of measuring at least one operating condition of the device 1. The operating conditions considered are in particular, but not limited to, the position and the inclination of the device 1. The measurement of the position of the device, for example by a GPS sensor, makes it possible to verify any abnormal movement of the device, for example in the event of severe weather, in order, if necessary, to find it easily. The inclination of device 1, measured for example by an inclinometer, makes it possible to check for any tilting of device 1.

Note that the term measurement module 11 applies here from a functional and not necessarily structural point of view. Indeed, the whole 110, 111, 112, formed by the cable 110, the winder 111 and the encoder wheel 112, can be physically distinct from the sensors 113, 114, and consequently said elements are potentially placed at distinct places of the device 1.

As illustrated in FIG. 2, the measurements taken by the measurement module 11 are transferred to the acquisition unit 15. The acquisition unit 15 is thus suitable for receiving the measurements, or even processing them, and relaying them to the monitoring system. remote transmission 12. The data acquisition unit is also able to control the measurement module 11, that is to say to manage the measurement parameters of the measurement module 11, for example the frequency of measurement of the rotation of the encoder wheel and/or sensors 113, 114. The remote transmission system 12 is capable of transmitting the measurements taken by the measurement module 11 via a satellite network, more preferably via the GSM network, to a receiver system, such as a server or a computer. The remote transmission systems 12 capable of being incorporated into the device 1 are known from the state of the art. According to a particular embodiment, the remote transmission system 12 can also be included in the acquisition unit 15.

The measurements can be transmitted continuously by the remote transmission system 12. However, the location of the device 1 can induce limited access, for example intermittent, to the network. According to one embodiment of the invention, the acquisition unit 15 is therefore suitable for storing measurement signals from the measurement module 11. Thus, when the network for the transmission of measurements is not accessible, the unit 15 stores the measurements for subsequent transmission by the remote transmission system 12. This embodiment also allows periodic transmission of the measurements, configured to take place a defined number of times per month, per week or even per day, preferably daily. Thus, the remote transmission system 12 is only activated at the scheduled transmission times, thus limiting the consumption of the remote transmission system 12 and consequently that of the device 1.

The measurement of the melting on the surface of the glacier is carried out by the measurement module 11, more particularly by the whole 110, 111, 112 formed by the cable 110, the reel 111 and the encoder wheel 112, illustrated in FIG. 3A and 3B . The cable 110 is connected by a first portion 1100, even a first end, to a positioning element 115 capable of anchoring the first portion 1100 , even the first end, of the cable in the drilled hole. The cable 110 is connected by a second portion 1101, or even a second end, to a winder 111. The winder 111 is suitable for winding the cable 110 by exerting a restoring force on the cable 110, so as to hold the cable 110 in tension between said first and second portions, or even between its two ends.

The cable 110 is further arranged so that a third portion 1102 of the cable 110, located between said first and second portions, or even between the two ends of the cable 110, is accommodated, preferably in contact, along at at least a part of the circumference of the encoder wheel 112, for example in a groove 1120. The encoder wheel 112 is configured fixedly with respect to the winder 111, and said part of the encoder wheel 112 is configured so that a movement of the third portion 1102 of the cable 110, when the cable 110 is wound by the winder 111, causes the rotation of the encoder wheel 112 along an axis of rotation passing through the center of the wheel.

The cable 110 is intended to be inserted into a hole drilled vertically in the ice or snowpack. To do this, a vertical drilling is carried out beforehand on the surface of the glacier by techniques known to those skilled in the art, in particular using a steam probe, or using a drill. Once the cable 110 has been inserted into the drilled hole, the first portion 1100 of the cable 110 is held by the positioning element 115 at a fixed point of the drilled hole, preferably at the bottom of the drilled hole. The positioning element can for example be an anchor deploying in the drilled hole or a ballast initially deposited in support at the bottom of the drilled hole, preferably weighing between 100 g and 1 kg, more preferably between 300 g and 700 g. The use of a ballast constitutes a preferred embodiment of the invention, to which reference is made below.

When the surface of the glacier melts, the surface of the ice or the snowpack lowers relative to the bottom of the drilled hole. The device 1 being placed on said surface, the distance between the ballast 115 and the reel 111 decreases. As this distance is reduced, the reel 111 winds the cable 110 according to a rotational movement illustrated in FIG. 3, so that the cable 110 remains in tension between the first 1100 and second 1101 portions, even between its two ends. The winding of the cable induces a displacement of the third portion 1102 of the cable 110 and a corresponding rotation of the encoder wheel 112. By measuring the rotation of the encoder wheel 112, a continuous measurement of the melting of snow and/or ice on the surface of the glacier is advantageously obtained.

The ballast 115 being deposited in support at the bottom of the drilled hole, the length of the cable 110 between the first 1100 and third 1102 portions corresponds at least to the depth of the drilled hole. This particular embodiment makes it possible to benefit from a cast iron measurement capacity equal to the depth of the drilled hole. More particularly, the length of cable 110 between said portions is between 5 and 20 meters, preferably between 8 and 15 meters. Thus, if we consider a surface melting of the glacier of 10 meters per year in the ablation zone of the glacier, the device 1 potentially makes it possible to measure the surface melting of a glacier over an extended period, and in particular over about a year.

Preferably, the cable 110 is of circular section, thus making it possible to limit its wind resistance, in particular on a possible emerged portion. Indeed, in the alternative where the device is free of a tube extending the body 10 and configured so as to be partially inserted into the drilled hole, the cable is likely to be exposed to the weather on a portion located between the surface of the glacier and the body 10 of the device 1, and more particularly the measurement module 11.

The cable 110 is made from a non-elastic material resistant to the meteorological conditions observable on a glacier, and in particular to low temperatures and high humidity. The material may be metal such as stainless steel or preferably a synthetic material, preferably polyamide, more preferably nylon. The use of a synthetic material has indeed advantages over metal. For one thing, a synthetic rope is lighter and more flexible than a metal rope. On the other hand, a synthetic cable can be pretreated to improve its resistance to weather conditions, in particular by waterproofing. In addition, a synthetic cable is compatible with commercial reels of lower cost, weight and power consumption than metal cable reels. Preferably, the winders used in the measurement module 11 are self-retracting, more preferably comprising a leaf spring.

The encoder wheel 112 according to the invention can be a commercial wheel suitable for accommodating, for example in a groove 1120, the cable 110 according to the characteristics described above. Preferably, the encoding street 112 gives an accuracy of measurement of the length of wound cable 110 of between 10 cm and 1 mm. According to a particular embodiment, an OTT SE 200 encoder wheel is used.

The relative position of the cable 110, the reel 111 and the encoder wheel 112 is chosen so as to allow the winding of the cable 110 and the rotation of the encoder wheel 112 while preventing the movement of the cable 110 from being hindered at a any point of its course. Depending on the diameters of the winder 111 and of the encoder wheel 112, it may be advantageous to position lugs 116 so as to guide the path of the cable 110. According to a particular embodiment, the cable passes through a slot 117 to be deflected by at least one lug 116 so as to bypass the winder 111. The slot 117, the winder 111 and the encoder wheel 112 being aligned, two additional lugs 116 guide the cable 110 so that the third portion 1102 of the cable 110 is accommodated along part of the circumference of the encoder wheel 112 by making a 180° turn to the winder 111. According to an alternative embodiment, it is possible that the light 117, the encoder wheel 112 and reel 111 forms a 90° bend, whereby cable 110 is received along part of the circumference of encoder wheel 112 making a 90° bend to reel 111.

The device 1 according to the characteristics previously described, used alternatively or combined, can be used in a method 2 for measuring the melting at the surface of a glacier. Method 2 has the previously described advantages of device 1, and in particular the continuous, autonomous and remote measurement of the surface melting of a glacier over an extended period of time, preferably over a year. In addition, the limitation of the cost and the weight of the device 1 as well as the movements on the ground of an operator, facilitates the deployment of a plurality of devices to measure the melting on the surface of the glacier in several points, even a multitude of points, preferably in the ablation zone of the glacier. Thus, method 2 not only makes it possible to measure the melting at the surface of a glacier, but in addition to carry out a quantification of the melting on the scale of the glacier, for example using about twenty devices distributed over the glacier.

Certain steps of the method 2, according to one embodiment of the invention, are represented in FIG. 4. The method 2 comprises in particular a first step of taking measurements 20, and in particular of the measurement 200 of the melting at the surface of the glacier. As described previously, the measurement 200 of the melting on the surface of the glacier by the measurement module 11, controlled by the acquisition unit 15, comprises a progressive winding 2001 of the cable 110 by the winder 111 as the surface of the glacier melts, causing a displacement of the third portion 1102 of cable 110 in contact with the encoder wheel 112. Said displacement induces a rotation 2002 of the encoder wheel 112.

The degree of rotation 2002 of the encoder wheel 112 is measured 2003, preferably by the encoder wheel 112. The degree of rotation 2002 is converted 2004 into a length of cable 110 wound up, by the acquisition unit 15 or by the encoder wheel 112 , the coiled cable length being equal to a cast height measurement in the present invention.

The taking 20 of the measurements can also comprise the measurement 201 of at least one environmental condition by at least one sensor 113 capable of measuring at least one environmental condition of the device. The measurement 201 of at least one environmental condition, for example the temperature, the force of the wind, the sunshine and/or the height of snow deposited on the surface of the glacier can thus supplement the measurement of the melting on the surface of the glacier, in particular in order to establish a numerical model of melting on the glacier surface. This embodiment of method 2 is particularly advantageous for quantifying the melting at the surface of a glacier in a punctual or distributed manner by multiplying the number of devices 1 on the surface of the glacier. For example, the measurement of melting 200 can be correlated to the sunshine, for example according to the adret or shady side, as well as to the variation of the sunshine during the duration of the measurement.

The measurement 20 can also comprise the measurement 202 of at least one operating condition by at least one sensor 114 capable of measuring at least one operating condition of the device 1. The measurement 202 of at least one operating condition of the device 1 makes it possible to ensure the correct operation of the device independently of the melting measurement at the surface of the glacier. The operating conditions envisaged are for example the inclination or the position of the device 1. A modification of the position of the device may occur, caused for example by bad weather. This displacement can induce unwinding of the cable 110, or cause the ballast 115 to no longer rest against the bottom of the hole drilled in the glacier, disturbing the measurement 200 of the melting at the surface of the glacier. A modification of the inclination of the device 1, or even its tilting, may also occur. It should be noted that an inclination of the device 1 does not disturb the progressive winding of the cable and therefore is not likely to disturb the measurement of the cast iron by the device 1. On the other hand, a tilting of the device can cause possible discomfort or even a blocking of the winding of the cable 110. By measuring 202 at least one operating condition of the device 1, it is possible to more reliably identify a malfunction of the device, or even the causes of the malfunction, and potentially to limit , or even avoid unnecessary movements of an operator.

As soon as the measurements are taken 20, they can be transmitted 21 to the acquisition center 15 and relayed to the remote transmission system 12, intended for a receiving system, such as a server or a computer, preferably via the network GSM.

As access to the GSM network may be limited on the glacier, the measurements can be stored 22 by the acquisition unit 15 in order to avoid loss of measurements. A subsequent transmission is then performed by the teletransmission system 21, when the network is accessible again. In addition, the storage step 22 provides an alternative to a continuous transmission 21 of the measurements. Indeed, thanks to the storage 22 of the measurements, their transmission 21 can be carried out discontinuously, preferably daily. Thus, the transmission system is not activated continuously, thus increasing the autonomy of device 1.

Following the transmission 21, the measurements are received 23 by a receiving system such as a server or a computer for their storage or for their use by an operator. If necessary, measurement instructions can be transmitted remotely by a transmitter system possibly confused with said receiver system, to the remote transmission system 12 and transmitted to the acquisition center 15. Thus, the parameters for taking measurements by the measurement module 11 can be modified 24 by the acquisition unit 15, such as the measurement frequency of the sensors 113, 114, the frequency of sending the rotation measurements of the encoder wheel 112 to the acquisition unit 15, and/or the frequency of sending by the remote transmission system 12. It is also envisaged that a measurement of an operating condition of the device 1 be recognized as abnormal and trigger the emission of an alert to warn an operator .

The invention is not limited to the embodiments described above and extends to all the embodiments covered by the claims.

List of references
1 Measuring device
10 Device body
11 Measurement module
110 Cable
1100 First portion
1101 Second portion
1102 Third Portion
111 Winder
112 Encoder wheel
113 Sensor
114 Sensor
115 Positioning element
12 Remote transmission system
13 Stand
14 Battery
141 Charging module
15 Acquisition center
16 Opening
160 door
161 Cap
2 Method of measurement
20 Taking measurements
200 Measurement of glacier surface melting
2001 Cable winding
2002 Rotation of the encoder wheel
2003 Measurement of rotation
2004 Conversion to cast height
201 Measure environmental condition
202 Measure operating condition
21 Storage
22 Transmission of measurements
23 Receipt of measurements
24 Change of measurement instructions

Claims (15)

Device (1) for measuring the surface melting of a glacier comprising:

• a module (11) for measuring the surface melting of the glacier;
• an acquisition unit (15) able to drive the measurement module (11) and to receive a measurement signal from the measurement module (11);
• a remote transmission system (12) of the measurement signal transmitted from the measurement module (11) by the acquisition center (15);
• a support (13) configured to support at least part of the measurement module (11), and
• a battery (14) capable of powering at least the measurement module (11), the acquisition unit (15) and the remote transmission system (12);
  characterized in that the measurement module (11) comprises:
• a cable (110) of which a first portion (1100) is intended to be anchored in a hole drilled in the glacier;
• a winder (111) adapted to wind the cable (110) by a second portion (1101) of the cable (110), so as to maintain the cable (110) in tension between said first and second portions;
• an encoder wheel (112) fixedly configured with respect to the winder and so as to accommodate, along at least part of its circumference, a third portion (1102) of the cable (110) located between said first and second portions so that the encoder wheel (112) is driven in rotation during winding of the cable (110) by the winder (111); the winder (111) and the encoder wheel (112) being arranged substantially plumb with the hole drilled using the support (13) placed on the glacier, so that the melting on the surface of the glacier induces the winding of the cable by the reel (111) and a corresponding rotation of the encoder wheel (112), the remote transmission system (12) therefore being able to emit a measurement signal proportional to the melting of the surface of the glacier.

Device (1) according to the preceding claim, in which the measurement module (11) comprises at least one sensor (113) capable of measuring at least one environmental condition of the device. Device (1) according to any one of the preceding claims, in which the measurement module (11) comprises at least one sensor (114), such as an inclinometer or a GPS sensor, capable of measuring at least one operating condition of the device (1), such as the inclination or the position of the device (1). Device (1) according to any one of the preceding claims, in which the acquisition unit (15) is able to store measurement signals coming from the measurement module (11). Device (1) according to any one of the preceding claims, in which the retractor (111) is a self-retracting retractor, preferably comprising a leaf spring. Device (1) according to any one of the preceding claims, further comprising a ballast (115) fixed to the cable to anchor the first portion (1100) of the cable in the drilled hole, preferably the ballast being initially deposited in support of the bottom of the drilled hole. Device (1) according to any one of the preceding claims, in which the cable (110) is made of a synthetic material, preferably of polyamide, and more preferably of nylon. Device (1) according to any one of the preceding claims, in which the initial length of the cable (110) between the said first (1100) and third (1102) portions is of a length comprised between 5 and 20 meters, preferentially between 8 and 15 meters. Device (1) according to any one of the preceding claims, in which the cable (110) is of circular section. Device (1) according to any one of the preceding claims, further comprising a charging module (141) for the battery (14), more particularly a photovoltaic panel. Method (2) for measuring the melting at the surface of a glacier using at least one device (1) according to any one of Claims 1 to 10, comprising the following steps:

• the taking (20) of measurements (200) of the melting at the surface of the glacier by the measurement module (11) controlled by the acquisition unit (15), each measurement (200) comprising:
  • a progressive winding (2001) of the cable (110) by the reel (111) as the surface of the glacier melts, causing a displacement of the third portion (1102) of cable;
  • a rotation (2002) of the encoder wheel (112) induced by the winding of the cable (110);
  • a measurement (2003) of the degree of rotation of the encoder wheel (112);
  • converting (2004) the degree of rotation measurement (2003) to a cast height measurement;
• the transmission (21), by the remote transmission system (12), of the measurements taken (20), intended for a receiver system, such as a server, preferably via the GSM network;

Method (2) according to claim 11, in which, the measurement module (11) comprising at least one sensor (113) capable of measuring at least one environmental condition of said device, the method (2) further comprises a measurement (201 ) of said at least one environmental condition. Method (2) according to either of Claims 11 and 12, in which the measurement module (11) comprises at least one sensor (114), such as an inclinometer or a GPS sensor, capable of measuring at least one operating condition of the device (1), the method further comprises measuring (202) said at least one operating condition of the device, such as the inclination or the position of the device. Method (2) according to any one of Claims 11 to 13, in which, the acquisition unit (15) being able to store measurement signals coming from the measurement module (11), the method comprising, between the steps taking measurements (20) and transmitting (21), a step of storing (22) by the acquisition unit (15) the measurements taken by the device (1). Method (2) according to claim 14, in which the transmission step (21) comprises the transmission of the stored data (22) by the acquisition unit (15), and is carried out discontinuously, preferably daily.