R. Longman

R. Longman
University of Hawai'i System · Geography

PhD

About

32
Publications
6,649
Reads
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938
Citations
Citations since 2016
19 Research Items
760 Citations
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2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
Additional affiliations
January 2010 - present
University of Hawaiʻi at Mānoa
Position
  • Lecturer
Description
  • Geography 300 (Introduction to Climatology) Geography 101 (The Natural Environment) Geography 101L (The Natural Environment Lab)

Publications

Publications (32)
Article
Full-text available
Drought is a prominent feature of Hawaiʻi’s climate. However, it has been over 30 years since the last comprehensive meteorological drought analysis, and recent drying trends have emphasized the need to better understand drought dynamics and multi-sector effects in Hawaiʻi. Here, we provide a comprehensive synthesis of past drought effects in Hawai...
Article
Full-text available
Drought is a growing threat to hydrological, ecological, agricultural, and socio-cultural systems of the tropics, especially tropical islands of the Pacific where severe droughts can compromise food and water security. Overcoming barriers to knowledge sharing between land managers and researchers is a critical cross-sector strategy for engaging and...
Article
Full-text available
With increasing needs for understanding historic climatic events and assessing changes in extreme weather to support natural hazard planning and infrastructure design, it is vital to have an accurate long-term hourly rainfall dataset. In Hawai'i, annual, monthly, and daily gauge data have been well-compiled and are accessible. Here, we compiled hou...
Article
Full-text available
Proper knowledge and understanding of climatic variability across different seasons are important in farm management. To learn more about the potential effects of climate change on dairying in Hawaii, we conducted a study on site-specific climate characterization using several variables including rainfall, wind speed, solar radiation, and temperatu...
Article
Full-text available
Gridded monthly rainfall estimates can be used for a number of research applications, including hydrologic modeling and weather forecasting. Automated interpolation algorithms, such as the “autoKrige” function in R, can produce gridded rainfall estimates that validate well but produce unrealistic spatial patterns. In this work, an optimized geostat...
Article
Full-text available
Tropical island ecosystems are highly vulnerable to the multiple threats of climate change (Nurse et al. 2014; Bonan 2008). In response, agencies and organizations are tasked with developing land-management strategies to help ecosystems adapt to changing environmental conditions (Swanston et al. 2016). Research has shown that proactive planning can...
Article
This article discusses the technologies and implementation of a climate data portal. This portal provides researchers and community stakeholders access to climatological data and resources, currently focusing on the state of Hawai'i. The portal provides interactive access to and visualization of hosted historical and near‐real‐time gridded maps and...
Article
Undisturbed trade-wind conditions comprise the most prevalent synoptic weather pattern in Hawai’i and produces a distinct pattern of orographic rainfall. Significant total rainfall contributions and extreme events are linked to four types of atmospheric disturbances: cold fronts, Kona lows, upper-tropospheric disturbances, and tropical cyclones. In...
Article
Full-text available
To better understand the historical and projected future climatology and hydrologic impacts of rainfall over the Hawaiian Islands, regional climate simulations over the main Hawaiian Islands were conducted for two 10-year periods using the Weather Research and Forecasting (WRF) model in two nested domains. The first (historical) simulation was driv...
Article
Almost all daily rainfall time series contain gaps in the instrumental record. Various methods can be used to fill in missing data using observations at neighboring sites (predictor stations). In this study, five computationally simple gap-filling approaches—normal ratio (NR), linear regression (LR), inverse distance weighting (ID), quantile mappin...
Article
Full-text available
Hurricane Lane (2018) was an impactful event for the Hawaiian Islands and provided a textbook example of the compounding hazards that can be produced from a single storm. Over a 4-day period, the island of Hawaiʻi received an island-wide average of 424 mm (17 in.) of rainfall, with a 4-day single-station maximum of 1,444 mm (57 in.), making Hurrica...
Article
It is a major challenge to develop gridded precipitation and temperature estimates that adequately resolve the extreme spatial gradients present in the Hawaiian Islands. The challenge is particularly pronounced because the available station networks are irregularly spaced and sparse, creating large uncertainties in gridded spatial meteorological es...
Article
Full-text available
Spatially continuous data products are essential for a number of applications including climate and hydrologic modeling, weather prediction, and water resource management. In this work, a distance-weighted interpolation method used to map daily rainfall and temperature in Hawaii is described and assessed. New high-resolution (250 m) maps were devel...
Article
This study presents a gridded meteorology intercomparison using the State of Hawaii as a testbed. This is motivated by the goal to provide the broad user community with knowledge of interproduct differences and the reasons differences exist. More generally, the challenge of generating station-based gridded meteorological surfaces and the difficulti...
Article
Full-text available
Long-term, accurate observations of atmospheric phenomena are essential for a myriad of applications, including historic and future climate assessments, resource management, and infrastructure planning. In Hawai‘i, climate data are available from individual researchers, local, State, and Federal agencies, and from large electronic repositories such...
Article
Full-text available
Background: Detailed assessments of species responses to climate change are uncommon, owing to the limited nature of most ecological and local climate data sets. Exceptions, such as the case of the Haleakalā silversword, can provide important insights into the complexity of biological responses to changing climate conditions. We present a time seri...
Article
Consistent increases in the strength and frequency of occurrence of the trade wind inversion (TWI) are identified across a ~40-yr period (1973-2013) in Hawaii. Changepoint analysis indicates that a marked shift occurred in the early 1990s resulting in a 20% increase in the mean TWI frequency between the periods 1973-90 and 1991-2013, based on the a...
Article
Full-text available
The goal of this study was to determine the effects of atmospheric demand on both plant water relations and daily whole-tree water balance across the upper limit of a cloud forest at the mean base height of the trade wind inversion in the tropical trade wind belt. We measured the microclimate and water relations (sap flow, water potential, stomatal...
Article
In the accompanying Comment, Hawkins et al.1 suggest that our index2 of the projected timing of climate departure from recent variability is biased to occur too early and is given with overestimated confidence. We contest their assertions and maintain that our findings are conservative and remain unaltered in light of their analysis.
Article
Trends in downwelling global solar irradiance were evaluated at high elevation sites on the island of Maui, Hawai‘i. Departures from monthly means were assessed for the 6-month Hawaiian wet and dry seasons over the period 1988 to 2012. Linear regression analysis was used to characterize trends in each season. For the dry season (May-October), stati...
Article
Full-text available
Growing evidence suggests short-duration climate events may drive community structure and composition more directly than long-term climate means, particularly at ecotones where taxa are close to their physiological limits. Here we use an empirical habitat model to evaluate the role of microclimate during a strong El Niño in structuring a tropical m...
Article
Full-text available
Ecological and societal disruptions by modern climate change are critically determined by the time frame over which climates shift beyond historical analogues. Here we present a new index of the year when the projected mean climate of a given location moves to a state continuously outside the bounds of historical variability under alternative green...
Article
The reliability of solar irradiance measurements is dependent on the calibration of the pyranometer used to make them. Internationally recognized standards for pyranometer calibrations require resources that may not be available to all observers. To fill this gap, we propose a method of homogenizing hourly solar radiation time series based on compa...
Article
Full-text available
Estimates of clear sky global solar irradiance using the parametric model SPCTRAL2 were tested against clear sky radiation observations at four sites in Hawai`i using daily, mean monthly, and 1 year mean model parameter settings. Atmospheric parameters in SPCTRAL2 and similar models are usually set at site-specific values and are not varied to repr...
Conference Paper
Despite the buffering effects of the tropical Pacific Ocean, secular trends in air temperature, precipitation, and stream discharge, especially during the past three decades, suggest that Hawai'i is already experiencing rapid climate change. Temperature increased statewide at 0.164 degrees C per decade during the 30 years ending in 2006, with more...
Article
Trends in clear-sky and total global solar irradiance for the period of 1988 to 2011 were evaluated based on data obtained from three high elevation climate stations on the island of Maui, Hawai'i. These climate stations, part of the HaleNet climate network, are located on the leeward slope of Haleakalā Volcano and cover a 870 m vertical elevation...
Article
Since its establishment in 1988, the HaleNet climate network has been recording microclimatic data on the slopes of Haleakala volcano. The 11 stations within the network encompass a 2020-m elevation gradient with both windward and leeward exposures. HaleNet is a unique resource for operational conservation biology activities, climate change monitor...

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Projects

Projects (2)
Project
Project
Create gridded daily fields of Daily Temperature (Min, Max, Air) and Rainfall for the entire Island chain at a 250 m resolution. These variables will then be used to estimate daily RH and Solar using an empirical model.