Climatological and Hydrological Observations for the South American Andes: In situ Stations, Satellite, and Reanalysis Data Sets

Abstract

Modern hydrology relies on multiple sources of information combined with climatological, hydrological and glaciological data. These data can be collected through various sources such as private initiatives by companies, research programs, and both national and international organisms. They also vary by types, e.g., in situ measurements, satellite, reanalysis and simulated data. Recently the ANDEX research project, as a GEWEX regional program, was created to understand the processes related to the hydrological cycle and energy fluxes in the Andean region from Colombia to Patagonia. It is quite challenging to carry out this program given the complex orography and diversity of climates from tropical to sub-polar climates. This review article is a compilation of the various databases that are useful for hydrometeorological research in the South American Andes. The National Meteorological and Hydrological Services in Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela and Argentina provide a large amount of data however the high-elevation areas are poorly instrumented and the number of stations varies greatly between the countries. National databases are only partially shared with the international bodies responsible for summarizing the existing data; this causes problems in term of data product assimilation. Across the entire continent, too few radiosondes are being used despite the fact that these data are crucial for validating and identifying problems in the atmospheric models. An increasing number of satellite data are available but it is difficult to assimilate them into the hydroclimatological models suited to the adjusted spatial and temporal resolutions. Specifically, for precipitation, we recommend merged products that account for the high spatial and temporal variability across the Andes. Finally, the international ANDEX program could be an excellent opportunity to increase the knowledge of the hydrological processes in the Andes.

Evaluation of multiple reanalyses in reproducing the spatio‐temporal variability of temperature and precipitation indices over southern South America

“…In this work, additionally to the stations network (which was used as reference), the CPC data set was included for comparison purposes. However, it is worth mentioning that other satellite‐based data sets are available for daily precipitation covering the whole SSA domain (Condom et al ., 2020), but unfortunately, they are not available for daily temperatures, which limits studies like the one proposed in the present work. In this regard, Taylor diagrams provide objective measures of observational uncertainties given by the distance between CPC and the reference point (in this case STN) in the cloud of points.…”

“…Notwithstanding, they are affected by inhomogeneities in the spatial patterns and temporal evolutions, which may be related to the different processes involved in data assimilation as well as to model uncertainty (Parker, 2016). Hence, intercomparison and evaluation studies against observational data become necessary, particularly in regions like southern South America, where data availability is often sparse (Condom et al ., 2020). A comparison across multiple data sets may help to bring consistency and ascertain our confidence in changes in extremes (Donat et al ., 2016).…”

“…Hence, considering multiple sources of information is strongly recommended to account for observational uncertainty, especially in regions like southern South America, where data availability and its resolution are often limited. A larger network of meteorological stations with extended spatial and temporal coverage is needed to assess the quality of the information provided by reanalyses, especially in regions with few measurements such as large portions of Argentina or the highest areas of the Andes (Condom et al ., 2020). Even more, results found in this study bring out the need to develop downscaling techniques in order to improve the misrepresentations of surface variables identified in the reanalyses, as well as to compare reanalyses performance in reproducing atmospheric circulation variables, which was probably associated to their differences found in the representation of extreme temperatures and precipitation.…”

Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America

“…While such excessive precipitation during the warm half of the year may be a result of overly strong convection or lack of topographic heterogeneity in the models (Chou et al 2014), part of this disagreement can also be due to the lack of ground stations in the mountainous regions (see difference between gauge-based and satellite-based observations; Fig. S1), as has been noted in many earlier studies (Baez-Villanueva et al 2018;Zubieta et al 2019;Condom et al 2020). Precipitation exhibits strong seasonality over the northern half of the continent, which is reflected in the large magnitude of its annual range (Fig.…”

Identificación de clústeres glaciares a lo largo de los Andes chilenos usando variables topoclimáticas

“…In order to identify the glacier similarities, we present a glacier cluster classification across the Chilean Andes using topo-climatic variables from the glacier national inventory of Chile and TerraClimate datasets, for 23,974 glaciers during the period 1980-2019 (Abatzoglou et al, 2018;DGA, 2015a). Goal in which the gridded data allows documenting the climate in poorly monitored regions (Condom et al, 2020;Manz et al, 2016;Schumacher et al, 2020). These glacier clusters will be calculated using the Partitioning Around Medoids (PAM) algorithm (Kaufman & Rousseeuw, 2008) and will allow identifying representative glaciers of zones with topo-climatic similarities.…”