TY  - JOUR
A1  - Hargis, Hailey
A1  - Gotsch, Sybil G.
A1  - Porada, Philipp
A1  - Moore, Georgianne W.
A1  - Ferguson, Briana
A1  - Van Stan, John T.
T1  - Arboreal epiphytes in the soil-atmosphere interface
BT  - how often are the biggest "buckets" in the canopy empty?
JF  - Geosciences
N2  - Arboreal epiphytes (plants residing in forest canopies) are present across all major climate zones and play important roles in forest biogeochemistry. The substantial water storage capacity per unit area of the epiphyte "bucket" is a key attribute underlying their capability to influence forest hydrological processes and their related mass and energy flows. It is commonly assumed that the epiphyte bucket remains saturated, or near-saturated, most of the time; thus, epiphytes (particularly vascular epiphytes) can store little precipitation, limiting their impact on the forest canopy water budget. We present evidence that contradicts this common assumption from (i) an examination of past research; (ii) new datasets on vascular epiphyte and epi-soil water relations at a tropical montane cloud forest (Monteverde, Costa Rica); and (iii) a global evaluation of non-vascular epiphyte saturation state using a process-based vegetation model, LiBry. All analyses found that the external and internal water storage capacity of epiphyte communities is highly dynamic and frequently available to intercept precipitation. Globally, non-vascular epiphytes spend <20% of their time near saturation and regionally, including the humid tropics, model results found that non-vascular epiphytes spend similar to 1/3 of their time in the dry state (0-10% of water storage capacity). Even data from Costa Rican cloud forest sites found the epiphyte community was saturated only 1/3 of the time and that internal leaf water storage was temporally dynamic enough to aid in precipitation interception. Analysis of the epi-soils associated with epiphytes further revealed the extent to which the epiphyte bucket emptied-as even the canopy soils were often <50% saturated (29-53% of all days observed). Results clearly show that the epiphyte bucket is more dynamic than currently assumed, meriting further research on epiphyte roles in precipitation interception, redistribution to the surface and chemical composition of "net" precipitation waters reaching the surface.
KW  - precipitation
KW  - interception
KW  - bromeliad
KW  - vascular epiphyte
KW  - non-vascular epiphyte
KW  - lichens
KW  - bryophytes
KW  - water storage capacity
Y1  - 2019
U6  - https://doi.org/10.3390/geosciences9080342
SN  - 2076-3263
VL  - 9
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Hierro, Rodrigo
A1  - Burgos Fonseca, Y.
A1  - Ramezani Ziarani, Maryam
A1  - Llamedo, P.
A1  - Schmidt, Torsten
A1  - de la Torre, Alejandro
A1  - Alexander, P.
T1  - On the behavior of rainfall maxima at the eastern Andes
JF  - Atmospheric Research
N2  - In this study, we detect high percentile rainfall events in the eastern central Andes, based on Tropical Rainfall Measuring Mission (TRMM) with a spatial resolution of 0.25 × 0.25°, a temporal resolution of 3 h, and for the duration from 2001 to 2018. We identify three areas with high mean accumulated rainfall and analyze their atmospheric behaviour and rainfall characteristics with specific focus on extreme events. Extreme events are defined by events above the 95th percentile of their daily mean accumulated rainfall. Austral summer (DJF) is the period of the year presenting the most frequent extreme events over these three regions. Daily statistics show that the spatial maxima, as well as their associated extreme events, are produced during the night. For the considered period, ERA-Interim reanalysis data, provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) with 0.75° x0.75° spatial and 6-hourly temporal resolutions, were used for the analysis of the meso- and synoptic-scale atmospheric patterns. Night- and day-time differences indicate a nocturnal overload of northerly and northeasterly low-level humidity flows arriving from tropical South America. Under these conditions, cooling descending air from the mountains may find unstable air at the surface, giving place to the development of strong local convection. Another possible mechanism is presented here: a forced ascent of the low-level flow due to the mountains, disrupting the atmospheric stratification and generating vertical displacement of air trajectories. A Principal Component Analysis (PCA) in T-mode is applied to day- and night-time data during the maximum and extreme events. The results show strong correlation areas over each subregion under study during night-time, whereas during day-time no defined patterns are found. This confirms the observed nocturnal behavior of rainfall within these three hotspots.
KW  - South-America
KW  - rainy-season
KW  - part I
KW  - precipitation
KW  - TRMM
KW  - climate
KW  - summer
KW  - circulation
KW  - monsoon
KW  - systems
Y1  - 2019
U6  - https://doi.org/10.1016/j.atmosres.2019.104792
SN  - 0169-8095
VL  - 234
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  -