Matthew G. Fearon

BEYOND POTENTIAL VEGETATION: COMBINING LIDAR DATA AND A HEIGHT‐STRUCTURED MODEL FOR CARBON STUDIES

Carbon estimates from terrestrial ecosystem models are limited by large uncertainties in the current state of the land surface. Natural and anthropogenic disturbances have important and lasting influences on ecosystem structure and fluxes that can be difficult to detect or assess with conventional methods. In this study, we combined two recent advances in remote sensing and ecosystem modeling to improve model carbon stock and flux estimates at a tropical forest study site at La Selva, Costa Rica (10°25′ N, 84°00′ W). Airborne lidar remote sensing was used to measure spatial heterogeneity in the vertical structure of vegetation. The ecosystem demography model (ED) was used to estimate the consequences of this heterogeneity for regional estimates of carbon stocks and fluxes. Lidar data provided substantial constraints on model estimates of both carbon stocks and net carbon fluxes. Lidar-initialized ED estimates of aboveground biomass were within 1.2% of regression-based approaches, and corresponding model estimates of net carbon fluxes differed substantially from bracketing alternatives. The results of this study provide a promising illustration of the power of combining lidar data on vegetation height with a height-structured ecosystem model. Extending these analyses to larger scales will require the development of regional and global lidar data sets, and the continued development and application of height structured ecosystem models.

Integrating SAR and optical imagery for regional mapping of paddy rice attributes in the Poyang Lake Watershed, China

The development of agricultural monitoring tools is a focus of the Group on Earth Observations for the Global Earth Observation System of Systems (GEOSS). This requires combining synthetic aperture radar (SAR) and optical satellite sensors to provide more meaningful information in an operational context. The goal of this research was to characterize paddy rice agro-ecological attributes in an operational context. A decision tree framework combined multitemporal and multiscale PALSAR, MODIS, and Landsat observations to map rice extent, hydroperiod, crop calendar, and cropping intensity. The study was carried out in the Poyang Lake Watershed, Jiangxi Province, China. A multiseason field campaign was carried out to calibrate algorithms and validate the rice maps. The field data corresponded relatively well with the remote sensing metrics and validation found that the derived rice paddy maps possessed a high overall accuracy of 89%. The rice maps indicate that the watershed has 25% rice agriculture with 85% of all paddies undergoing a double-crop management pattern. Remotely sensed metrics showed that inundation periods for early rice were typically twice as long as inundation periods between crops, which corresponded to site level measurements at double crop locations. Using hydroperiod and crop intensity information a crop calendar indicated that the day of year (DOY) planting and harvesting activities was typically around DOY 77 and 329, respectively. The automated approach combining SAR and optical platforms with continental-scale acquisition strategies might allow for large-area, operational agricultural rice mapping. This can contribute to a GEOSS framework for improved agricultural monitoring.

A bias corrected WRF mesoscale fire weather dataset for Victoria, Australia 1972-2012

Climatology data of fire weather across the landscape can provide science-based evidence for informing strategic decisions to ameliorate the impacts (at times extreme) of bushfires on community socio-economic wellbeing and to sustain ecosystem health and functions. A longterm climatology requires spatial and temporal data that are consistent to represent the landscape in sufficient detail to be useful for fire weather studies and management purposes. To address this inhomogeneity problem for analyses of a variety of fire weather interests and to provide a dataset for management decision-support, a homogeneous 41-year (1972-2012), hourly interval, 4 km gridded climate dataset for Victoria has been generated using a combination of mesoscale modelling, global reanalysis data, surface observations, and historic observed rainfall analyses. Hourly near-surface forecast fields were combined with Drought Factor (DF) fields calculated from the Australian Water Availability Project (AWAP) rainfall analyses to generate fields of hourly fire danger indices for each hour of the 41-year period. A quantile mapping (QM) bias correction technique utilizing available observations during 19962012 was used to ameliorate any model biases in wind speed, temperature and relative humidity. Extensive evaluation was undertaken including both quantitative and case study qualitative assessments. The final dataset includes 4-km surface hourly temperature, relative humidity, wind speed, wind direction, Forest Fire Danger Index (FFDI), and daily DF and Keetch-Byram Drought Index (KBDI), and a 32-level full three-dimensional volume atmosphere.

Herbert Riehl: Intrepid and Enigmatic Scholar

Herbert Riehl, known as the “father of tropical meteorology,” certainly made outstanding contributions to this field of study. Yet, when his oeuvre is examined retrospectively, there is strong evidence that his view was global and encompassed processes that cut across the latitudinal bands of the tropics, subtropics, and midlatitudes. His pathway into meteorology was unique as a Jewish man who immigrated to the United States from Germany in 1933—that point in time when the fascist regime in Germany gained significant power. Meteorology was not his first choice as a career, but circumstances related to imminent world war led him to the study of meteorology. He was inspired by his teaching and research experiences at the Institute of Tropical Meteorology in Puerto Rico during World War II. Further, he found his scientific calling in the milieu of “Rossbys School” at the University of Chicago (U of C) following the war. Particular attention is paid herein to his early work from the mid-1940s through the lat...