Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

Beusekom, Ashley E. Van; González, Grizelle; Scholl, Martha A.

doi:10.5194/acp-17-7245-2017

Cited by 26 publications

(18 citation statements)

References 49 publications

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“…When mountains are narrower and shorter, and below the trade-wind inversion, as on the islands of Oahu and New Caledonia, maximum MAP typically occurs at or near the peak ( Fig 7C and 7D ); windward slopes receive more MAP than leeward slopes, but the difference is not as large. The highest peaks in the Luquillo Mountains, at 1,050–1,075 m in elevation, are below the average altitude of the cloud-capping trade-wind inversion (2,140 m in eastern Puerto Rico, based on San Juan radiosonde data [ 107 ]. A transect of elevation and MAP (estimated by our spatial model) through the Luquillo Mountains from the east shows that maximum MAP is located near the first major orographic barrier ( Fig 7E ), similar to Oahu and New Caledonia, and also to the relatively low mountain range of Dominica, another Caribbean island (not shown) [ 108 ].…”

Section: Discussionmentioning

confidence: 99%

Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications

et al. 2017

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Mountains receive a greater proportion of precipitation than other environments, and thus make a disproportionate contribution to the world’s water supply. The Luquillo Mountains receive the highest rainfall on the island of Puerto Rico and serve as a critical source of water to surrounding communities. The area’s role as a long-term research site has generated numerous hydrological, ecological, and geological investigations that have been included in regional and global overviews that compare tropical forests to other ecosystems. Most of the forest- and watershed-wide estimates of precipitation (and evapotranspiration, as inferred by a water balance) have assumed that precipitation increases consistently with elevation. However, in this new analysis of all known current and historical rain gages in the region, we find that similar to other mountainous islands in the trade wind latitudes, leeward (western) watersheds in the Luquillo Mountains receive lower mean annual precipitation than windward (eastern) watersheds. Previous studies in the Luquillo Mountains have therefore overestimated precipitation in leeward watersheds by up to 40%. The Icacos watershed, however, despite being located at elevations 200–400 m below the tallest peaks and to the lee of the first major orographic barrier, receives some of the highest precipitation. Such lee-side enhancement has been observed in other island mountains of similar height and width, and may be caused by several mechanisms. Thus, the long-reported discrepancy of unrealistically low rates of evapotranspiration in the Icacos watershed is likely caused by previous underestimation of precipitation, perhaps by as much as 20%. Rainfall/runoff ratios in several previous studies suggested either runoff excess or runoff deficiency in Luquillo watersheds, but this analysis suggests that in fact they are similar to other tropical watersheds. Because the Luquillo Mountains often serve as a wet tropical archetype in global assessments of basic ecohydrological processes, these revised estimates are relevant to regional and global assessments of runoff efficiency, hydrologic effects of reforestation, geomorphic processes, and climate change.

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Section: Discussionmentioning

confidence: 99%

Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications

et al. 2017

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“…From space, active measurements are carried out by CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) on the CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite (Winker et al, 2010). A valid retrieval of the z base can only be ensured if the signal of CALIOP reaches the Earth's surface, which is only possible in the case of low optical thickness.…”

Section: Introductionmentioning

confidence: 99%

Cloud base height retrieval from multi-angle satellite data

et al. 2019

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Abstract. Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base height (zbase) from satellite measurements. This study presents a new approach to retrieve cloud base heights using the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite. It can be applied if some cloud gaps occur within the chosen distance of typically 10 km. The MISR cloud base height (MIBase) algorithm then determines zbase from the ensemble of all MISR cloud top heights retrieved at a 1.1 km horizontal resolution in this area. MIBase is first calibrated using 1 year of ceilometer data from more than 1500 sites within the continental United States of America. The 15th percentile of the cloud top height distribution within a circular area of 10 km radius provides the best agreement with the ground-based data. The thorough evaluation of the MIBase product zbase with further ceilometer data yields a correlation coefficient of about 0.66, demonstrating the feasibility of this approach to retrieve zbase. The impacts of the cloud scene structure and macrophysical cloud properties are discussed. For a 3-year period, the median zbase is generated globally on a 0.25∘ × 0.25∘ grid. Even though overcast cloud scenes and high clouds are excluded from the statistics, the median zbase retrievals yield plausible results, in particular over ocean as well as for seasonal differences. The potential of the full 16 years of MISR data is demonstrated for the southeast Pacific, revealing interannual variability in zbase in accordance with reanalysis data. The global cloud base data for the 3-year period (2007–2009) are available at https://doi.org/10.5880/CRC1211DB.19.

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“…Cloud base heights over land are generally higher than those over islands, which are closely coupled to the oceanic boundary layer (Beusekom et al. 2017). Upward shifts of both the base height and the frequency of convective and orographic clouds can also be caused by lower elevation deforestation (Lawton et al.…”

Section: Discussionmentioning

confidence: 99%

“…Variations within the Intertropical Convergence Zone, El Niño Southern Oscillation, and Hadley circulation have all been attributed to changes in the height of the TWI (Schubert et al 1995;Loope and Giambelluca 1998;Sperling et al 2004;Cao et al 2007;Crausbay et al 2015). In oceanic settings, however, a stronger TWI can increase oceanic cloud cover and generally lowers the cloud base height (Stevens 2004;Myers and Norris 2013;Beusekom et al 2017). This effect could additionally explain downward shifts of cloud forest elevational limits with warming climates in an oceanic setting such as Tenerife.…”

Section: Broader Implications For Montane Cloud Forest Biodiversitymentioning

confidence: 99%

Long‐term cloud forest response to climate warming revealed by insect speciation history*

et al. 2020

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Montane cloud forests are areas of high endemism, and are one of the more vulnerable terrestrial ecosystems to climate change. Thus, understanding how they both contribute to the generation of biodiversity, and will respond to ongoing climate change, are important and related challenges. The widely accepted model for montane cloud forest dynamics involves upslope forcing of their range limits with global climate warming. However, limited climate data provides some support for an alternative model, where range limits are forced downslope with climate warming. Testing between these two models is challenging, due to the inherent limitations of climate and pollen records. We overcome this with an alternative source of historical information, testing between competing model predictions using genomic data and demographic analyses for a species of beetle tightly associated to an oceanic island cloud forest. Results unequivocally support the alternative model: populations that were isolated at higher elevation peaks during the Last Glacial Maximum are now in contact and hybridizing at lower elevations. Our results suggest that genomic data are a rich source of information to further understand how montane cloud forest biodiversity originates, and how it is likely to be impacted by ongoing climate change.

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Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

Cited by 26 publications

References 49 publications

Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications

Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications

Cloud base height retrieval from multi-angle satellite data

Long‐term cloud forest response to climate warming revealed by insect speciation history*

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