Climate Change in the tropical Andes - Part 2 by Proyecto PRAA

Climate Change in the tropical Andes Impacts and consequences for glaciation and water resources Part II: Climate and Glacier Monitoring A report prepared by

MATHIAS VUILLE with contributions from BERNARD FRANCOU DOUGLAS R. HARDY GEORG KASER RAYMOND S. BRADLEY

Climate Change in the tropical Andes â&#x20AC;&#x201C; Impacts and consequences for glaciation and water resources Part II: Climate and Glacier Monitoring A report for CONAM and the World Bank prepared by

MATHIAS VUILLE (University of Massachusetts)

with contributions from BERNARD FRANCOU (IRD) DOUGLAS R. HARDY (University of Massachusetts) GEORG KASER (University of Innsbruck) RAYMOND S. BRADLEY (University of Massachusetts)

Amherst, Massachusetts, 29. May, 2007

Cover photo: Carsten Braun working on AWS on Nevado Illimani (6265 m), Cordillera Real, Bolivia, July 1997 (photo credit: M. Vuille)

TABLE OF CONTENTS 1) INTRODUCTION ...................................................................................................2 2) UMASS-CSRC ACTIVITIES .............................................................................3 3) INNSBRUCK-ITGG ACTIVITIES .....................................................................7 4) IRD ACTIVITIES ...................................................................................................11 REFERENCES ............................................................................................................16

1) INTRODUCTION This second report is intended to give a state-of-the-art overview of past and current monitoring and research activities by the Universities of Massachusetts (CSRC), Innsbruck (ITGG) and the IRD. It focuses exclusively on climatologic, glaciologic, and hydrologic monitoring networks which have been installed and maintained by the three groups. It does not, however, include activities by other foreign research groups nor does it discuss the networks maintained and operated by the national meteorological or hydrological services such as SENAMHI, INRENA or INAMHI. The report is meant to give an accurate description of current monitoring efforts, but it does not address the adequacy or shortcomings of these installations and monitoring sites. This issue is discussed separately in the third volume (see Part III: Future recommendations). We hope that the overview presented in this report can provide a starting point for discussions as to how this network could be better maintained and expanded in the near future. It may also serve as a reference framework regarding design and operation of future stations and monitoring networks. Ultimately the long-term goal of such a network must be to assure continuity of the data stream and procurement of long, reliable and homogeneous glacier and climate records from the tropical Andes for many more years to come.

2) UMASS-CSRC ACTIVITIES Climate monitoring activities by the Climate System Research Center (CSRC) at the University of Massachusetts, Amherst started in 1996, when a high-elevation station was deployed at 6515 m a.s.l. on the summit of Sajama, the highest peak in Bolivia (Hardy et al., 1998). Since then the group, lead by Dr. D.R. Hardy, has specialized in extreme high-elevation automated weather station (AWS) design and instrumentation. A second station was installed only a year later near the summit of Illimani in the Cordillera Real of Bolivia at 6265 m (Hardy et al., 2001). A third station was deployed in 2003 on Quelccaya Ice Cap in the Cordillera Vilcanota, Peru at 5670 m (Figure 1).

Quelccaya Ice Cap, Peru: 5670m (18,598ft)

Figure 1: AWS on the summit of Quelccaya Ice cap, Cordillera Vilcanota, Peru (Photo D.R. Hardy).

The main motivation for the installation of these AWS was to gain a better understanding of climate at these high-elevation sites, in support of tropical ice core interpretations. At all three sites long ice core records have since been retrieved (Thompson et al., 1985, 1998; Knuesel et al., 2002, 2005; Ramirez et al., 2003). It is generally acknowledged that the interpretation of these records, in particular variations in the stable water isotope composition, is not well constrained and that they lack an adequate calibration. The AWS deployed by the CSRC have helped in these calibration efforts by providing unique, on-site, high-elevation climate measurements. The clear focus on climate research rather than monitoring, however, has limited their duration of deployment. Operating these AWS for more than 3-4 years usually goes way beyond what funding agencies are willing to support, so after a few years of operation the stations generally have to be disassembled. Maintaining these high-elevation stations is extremely time consuming and expensive (see Part III: Future recommendations), but without

careful maintenance and calibration, data quality will rapidly deteriorate. At some sites the stations are even in danger of being buried and lost. AWS located on glaciers for example need to be constantly raised or lowered in order to prevent them from being buried by snow or melting out and tipping over. Frequent exchange of instruments is necessary in order to recalibrate sensors or replace damaged measurement devices. Today only one station, Quelccaya is still operating, while the climate monitoring on Sajama and Illimani came to an end several years ago (see Table 1) for financial reasons. The focus on supporting ice core calibration efforts also explains why these stations were all installed on the highest peaks, in contrast to the IRD and Innsbruck stations (see sections 3 and 4), which are usually located on or near the ablation zone of glaciers to monitor the glacier surface energy balance (SEB). STATION

CORDILLERA

COUNTRY

Sajama Illimani Quelccaya

C. Occidental C. Real C. Vilcanota

Bolivia Bolivia Peru

ELEVATION

START

END DATE

6515 m 6265 m 5670 m

9/1996 7/1997 8/2003

10/2000 11/2001 operating

Table 1: Table of AWS network maintained by the CSRC-UMass.

All CSRC stations are equipped with telemetry through a Geostationary Operational Environmental Satellite (GOES), which allows immediate data recovery and near real-time assessment of any unforeseen problems. Data are sent hourly to the satellite with a transmitter. This is essential given the remote high-elevation location of the stations, which precludes immediate and unscheduled visits for repair and service. In addition data is also stored on-site through a data logger, in case telemetry fails (e.g. when antenna is covered by snow), and it also allows storing additional data, which may exceed the transmission capacity. Measurements include all standard meteorological variables, such as wind speed and direction, barometric pressure, air temperature (aspirated and naturally ventilated), relative humidity (aspirated and naturally ventilated) and vapor pressure, incoming and reflected solar and longwave radiation, snow accumulation and ablation, snow surface temperature, and snow (firn) temperature at various depths (see Figure 2 and Table 2). The sampling interval and the interval at which data is stored and transmitted varies by station and sensor, but generally ranges on the order of 60 s to 10 min for sampling interval and 1-3 h for storage. The stations are powered by 12V DC systems, composed of 5-20 W solar panels and regulators which recharge sealed lead-acid batteries. The main problem with maintaining such remote high-elevation AWS is the difficulty of frequent and unscheduled visits. On average stations are serviced about once a year, when stations are raised, data is downloaded and sensors are replaced and brought back for calibration. In some years and locations (Illimani, in particular) snowfall was significantly higher than anticipated, which resulted in partial burial of the sensors. The changing distance between sensor and surface as snow accumulates throughout the wet season may also affect the data quality of some measurements. Nonetheless the stations have generally operated exceptionally well and provided several years of data from locations where previously absolutely no climatic information was available.

A more detailed description of the CSRC station design and operation of the AWS on Sajama can be found in Hardy et al., (1998, 2003).

Figure 2: Example from Quelccaya Ice cap of a fully automated and instrumented high-elevation weather station designed and maintained by D. R. Hardy (CSRC-UMASS). See text for detailed explanation.

Table 2: Configuration of the Sajama and Illimani AWS (Hardy et al., 1998).

3) INNSBRUCK-ITGG ACTIVITIES Glacier and climate monitoring activities by the University of Innsbruck Tropical Glaciology Group (ITGG) have focused primarily on the Cordillera Blanca in Peru. Much of their work was done in collaboration with local glaciologists, such as Jesus Gomez from INRENA and built on previous monitoring efforts and data collection by Electroperu S.A, which started runoff and precipitation measurements in the region back in 1953 (1949 in Paron). Ablation measurements on several glaciers started in the early the 1970s (Ames, 1985; Kaser et al., 1990), in particular on Yanamarey and Uruashraju glaciers (Figure 3). Early attempts to measure accumulation, however, were not successful, so that no long mass balance records exist for this region. Instead mass balance was reconstructed indirectly based on runoff records from the region (Kaser et al., 2003). The change of the terminus position is easier to assess than mass balance and has been determined annually for three small glaciers between the 1960s and 1994 (Ames et al., 1989, see also Table 3.). The ITGG built on these records and determined the terminus position of glaciers Vallunaraju and Chinchey using differential GPS (Global Positioning System) between 1999 and 2001.

Figure 3: Location of glaciers and AWS sites in the Cordillera Blanca, PerĂş, installed and maintained by ITGG (Juen, 2006).

Table 3: Historical and recent glaciological observations in the Cordillera Blanca, Peru (Juen, 2006).

The deployment of AWS by the ITGG began in 1999. Three AWS were installed and maintained for a varying amount of time. These include the Rurichinchey AWS, installed in September 1999 below the glacier at 4600 m a.s.l.; the Vallunaraju AWS, installed in May 2000 on a ridge at 5000 m a.s.l. alongside the glacier and a second Rurichinchey AWS, also installed on a ridge near the glacier at the equilibrium line altitude (ELA) of 5100 m a.s.l. in October 2000 (Georges and Kaser, 2002). An additional AWS was installed in 2002 near glacier Shallap (Table 4). The AWS are all equipped with similar instruments as the UMASS stations (see previous section), albeit that they are designed somewhat differently due to differing research questions. They are all equipped with sensors to measure wind speed and direction, air temperature and relative humidity (both aspirated and naturally ventilated) and incoming shortwave radiation. Two of the stations were later (in 2004) equipped with a precipitation balance. In March 2004 two energy balance stations were installed by ITGG on the glacier surface itself (Juen, 2006). These stations are designed to measure all relevant fluxes to establish a full glacier energy balance. The stations were deployed on Glacier Artesonraju at 4850 and 4750 m a.s.l., respectively, because IRD already maintained a runoff station below the glacier at the outlet of Lake Artesoncocha at 4200 m since April 2000 (see next section and Figure 4). Joining forces, combining measurements and exchanging data turned out to be a successful strategy and mutually beneficial for both groups. These energy balance stations were complemented with a high-elevation station at 5100 m on a side moraine of the glacier (Figure 5). The ITGG stations were not running continuously (see Table 4), for various reasons (Juen, 2006). There is, however, enough overlap between the individual records to allow for the creation of a continuous time series (e.g. with the first difference method, Vuille and Bradley, 2000) between 2000 and 2005.

Figure 4: Runoff gauge at the outlet of Lake Artesoncocha (4200 m a.s.l.), maintained by IRD. (Photo: B. Pouyaud, in Juen, 2006).

Figure 5: AWS near glacier Artesonraju at 5100 m a.s.l., maintained by ITGG. (Photo G. Kaser, in Juen, 2006).

Table 4: Summary diagram of AWS deployed in the Cordillera Blanca by ITGG (Juen, 2006).

4) IRD ACTIVITIES Glacier and climate monitoring activities by the Institut de Recherche pour le DĂŠveloppement (IRD, formerly ORSTOM), are the most extensive and long-lived of all three groups. The studies by IRD focus on glaciers in Ecuador, Peru and Bolivia, which are considered typical of the regional climate in the inner tropics (Ecuador), the subtropics (Peru) and the outer tropics (Bolivia), respectively. In general IRD tends to select a small and a large glacier at each study site, to assess differences in their sensitivity and response to climate change.

Figure 6: Location of glaciers monitored by IRD.

Glacier monitoring started in Bolivia in 1991 by installing ablation stakes on two glaciers, Chacaltaya and Zongo, both located close to La Paz in the Cordillera Real (Pouyaud et al., 1995; Francou et al., 1995). The first ablation stakes were installed on Zongo glacier in July 1991 (Francou et al., 1995; Ribstein et al., 1995a, Wagnon et al., 2001). A limnimetric station measuring the proglacial stream discharge at 4830 m complements the ablation measurement on the glacier and has been merged with older gauge readings by an electric power plant dating back to 1973 (Ribstein et al., 1995a, b). In addition two AWS were installed on Zongo in 1993 near the ELA at 5150 m and in the 11

ablation zone at 5060 m (Figure 7). In March 1996 these stations were complemented by a suite of sensors to measure the entire glacier energy balance and in 1998 by ultrasonic depth sounders (Wagnon et al., 1999; Sicart et al., 2002). Measurements include ventilated wet and dry bulb temperature, wind speed and direction, incident and reflected shortwave radiation, net all wave radiation, snow height change and snow temperatures at various depths. In addition nine different rain gauges surrounding the glacier have been operating since 1995. These precipitation measurements are complemented by 3-5 snow pits, which are dug every year in the accumulation area between 5500 m and 5700 m (see also Figure 9).

Figure 7: AWS on Zongo Glacier, Cordillera Real, Bolivia (photo: B. Francou).

On Chacaltaya a network of ablation stakes was installed in September 1991. This network was extended twice, in 1995 and in 1996 by adding additional stakes to achieve a better spatial coverage of the entire glacier (Francou et al., 2003). In August 1991 several rain gauges were installed surrounding the glacier, effectively complementing the existing long rainfall record at the nearby astronomical observatory, dating back to 1953. Because glacier Chacaltaya has almost completely disappeared, the monitoring activities

have mostly ceased and been transferred to Charquini glacier, located about half way between Chacaltaya and Zongo. A proglacial discharge station had already been installed there back in 1995. The glacier monitoring networks pioneered by IRD in Bolivia were later successfully implemented in Peru and Ecuador. In 1994 two glaciers in the Cordillera Blanca, Artesonraju and Yanamarey, were chosen for similar activities. Besides accumulation and ablation measurements the network also includes pluviometric readings and runoff measurements at the outlet of Lake Artesonraju below the glacier (see Figure 4 and Pouyaud et al., 1998). In Ecuador the ablation zone of glacier 15 on Antizana was the first to be equipped with a network of ablation stakes by IRD in June 1994 (Pouyaud et al., 1998). This stake network was expanded the following year and in 1996 pluviometers and a stream gauge below the glacier snout were added (Francou et al., 2004). Finally in September 1998 an AWS was deployed at 4890 m on the glacier ablation zone to complete the monitoring setup (Figure 8). Some of the radiometers needed for a complete glacier energy balance, however, were only installed in March 2002 (Favier et al., 2004). More recently glacier monitoring activities in Ecuador have been expanded to glacier Carihuayrazo (Francou et al., 2005).

Figure 8: Example of a glacier monitoring network by the IRD (example of Antizana 15, Ecuador), including mass balance stakes, AWS, several rain gauges and a stream gauge (Francou et al., 2004).

What sets the IRD activities apart from all other research groups is their maintenance of an extended network of ablation and accumulation stakes, which are visited monthly by IRD or affiliated personnel. These measurements have proven especially valuable as they allowed for the first time to assess in detail how accumulation and ablation vary throughout the year under tropical and subtropical conditions (Francou et al., 2003, 2004). These measurements are summarized in annual reports by the IRD and are also being furnished to the World Glacier Monitoring Service (WGMS) at the University of Z端rich, Switzerland, where the data is made available to the public (to access the data go to: http://www.geo.unizh.ch/wgms/). To get a sense of total mass accumulation in the higher reaches of the glacier, snow pits are dug roughly twice a year in the accumulation zone of all glaciers. An overview over the different mass balance measurements on the glacier, performed routinely by IRD personnel or their affiliates is given in Figure 9.

Figure 9: Mass balance measurements performed by IRD on various glaciers in the tropical Andes (Photo: B. Francou).

Finally IRD also monitors the extent of their glaciers annually with photogrammetric surveys and smaller glaciers such as Chacaltaya have been surveyed repeatedly with radar to estimate the change in total ice volume (Ramirez et al., 2001). These recent estimates have been put into a longer term context by comparing them with aerial photographs and satellite data (see Part I: The Scientific Basis). Today the network of monitoring sites maintained by IRD spans 11 different sites. A schematic overview over these activities is given in Table 5.

GLACIERS Zongo 16°S1 Chacaltaya1 16°S Charquini S1 16°S Charquini N1 16°S Sullcón 12°S2 Yanaramey2 10°S

BM + + + + + +

BH + + + + +

GTS + + +

APR + + + +

BE +

T, P + + +

+ +

Uruashraju3 10°S

Artesonraju2 9°S

Carihuairazo4 1°S Antizana 155 0°28S Antizana 125 Los Crespos 0°28S

+ + +

+ +

+ + +

+ +

ECONOMIC SETTING Hydropower La Paz Fresh water La Paz Fresh water La Paz Hydropower La Paz Fresh water Hydropower Lima Irrigation Peruvian coast Hydropower Irrigation Peruvian coast Hydropower Irrigation Peruvian coast Hydropower Irrigation Fresh water Quito Irrigation Fresh water Quito Irrigation

Table 5: The glacier monitoring network maintained by IRD and its South American partners. 1 IRD-IHH-COBEE-SENAMHI, 2IRD-UGRH-INRENA, 3INRENA, 4IRD-INAMHI, 5IRD-INAMHIEMAAP-Q. Bm: mass balance (stakes, pits, drillings), Bh: hydrological balance with rain gauge and runoff stations, GTS: ground topographical survey, APR: periodic aerophotogrammetrical restitution, Be: energy balance, T,P: basic meteorological station (temperature and pluviometry).

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