179 research outputs found
A precipitation-based regionalization for Western Iran and regional drought variability
Abstract. The spatial distribution of the seasonal and annual
precipitation was analyzed in western Iran using data
from 140 stations covering the period 1965–2000. Applying
the Precipitation Concentration Index (PCI), the intraannual
precipitation variability was also studied. Furthermore,
nine precipitation-derived parameters were used to regionalize
climate in western Iran using principal component
analysis and clustering techniques. Results suggest that five
spatially homogenous sub-regions can be identified characterized
by different precipitation regimes. The spatial pattern
of seasonal precipitation seems to be highly controlled by the
wide latitudinal extent of the region and by the pronounced
orographic relieves, and the time of occurrence of the maximum
precipitation varies from spring in the north to winter
in the south.
The time variability of dry and wet periods in the identified
sub-regions was analyzed using the Precipitation Index
(PI) and the existence of any long-term trend was tested. Results
show that the northern and southern regions of western
Iran are characterized by different climatic variability. Furthermore,
a negative long-term linear trend in the north and a
weak positive trend in the south of the study area have been
detected though they are not statistically significan
A Clean Energy Utility for Multifamily Housing in a Deregulated Energy Market
Energy efficiency and renewable energy (EERE) investment in multifamily residences in the United States has not kept pace with investment in resident-owned facilities. Split incentives, where owners cannot benefit economically from energy cost savings for residences and resident investment in EERE is not feasible, have posed a significant barrier. A clean energy utility is posited to circumvent this barrier. This utility would be responsible for power purchase from the grid, ideally as a real-time purchase agent from the grid manager; investment in energy efficiency and renewable energy; and demand management through control of water heating, as well as supply-side management through deployment of stored solar at near-peak grid power purchase cost. A clean energy fee is posed for recovery of costs, in contrast to typical consumption strategies (per kW h). A case study approach is employed to evaluate the feasibility of this type of utility of reducing carbon production in this building sector. Considered in the analysis is a 2008 multifamily facility located in the Midwest of the U.S., with apartment level interval meters for both power and water. Historical data from these meters were used to assess the savings and demand-side management potential from investments in improved efficiency lighting, refrigeration, heat pumps, and water heaters, as well as investments in solar PV and storage for supply-side management. The results show that the packaged retrofit EERE investment could yield costs for residents and profits for energy manager comparable to those in the current residential pricing scheme, while reducing grid-sourced energy by 42%. When solar PV and battery storage are added to the solution, it is shown that a clean energy fee structure can cost-effectively drive savings to over 54%. For new construction, even deeper cost effective savings are realizable. This research demonstrates the potential to drive deep energy savings in the multifamily building sector that can lower costs to residents through the establishment of clean energy utilities which recover investments in energy efficiency, demand management, and solar PV/battery systems through resident clean energy fees rather than consumption fees
Space-time variability of hydrological drought and wetness in Iran using NCEP/NCAR and GPCC datasets
Abstract. Space-time variability of hydrological drought
and wetness over Iran is investigated using the National
Centers for Environmental Prediction/National Center for
Atmospheric Research (NCEP/NCAR) reanalysis and the
Global Precipitation Climatology Centre (GPCC) dataset for
the common period 1948–2007. The aim is to complement
previous studies on the detection of long-term trends
in drought/wetness time series and on the applicability of
reanalysis data for drought monitoring in Iran. Climate
conditions of the area are assessed through the Standardized
Precipitation Index (SPI) on 24-month time scale, while
Principal Component Analysis (PCA) and Varimax rotation
are used for investigating drought/wetness variability, and
drought regionalization, respectively. Singular Spectrum
Analysis (SSA) is applied to the time series of interest to
extract the leading nonlinear components and compare them
with linear fittings.
Differences in drought and wetness area coverage resulting
from the two datasets are discussed also in relation to the
change occurred in recent years. NCEP/NCAR and GPCC
are in good agreement in identifying four sub-regions as principal
spatial modes of drought variability. However, the climate
variability in each area is not univocally represented
by the two datasets: a good agreement is found for southeastern
and north-western regions, while noticeable discrepancies
occur for central and Caspian sea regions. A comparison
with NCEP Reanalysis II for the period 1979–2007,
seems to exclude that the discrepancies are merely due to the
introduction of satellite data into the reanalysis assimilation
schem
Spatial and temporal variability of precipitation and drought in Portugal
The spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of 1941–2006. Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI), was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI) and the modified PDSI for Mediterranean conditions (MedPDSI) were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them
One-year prognosis of patients with normal myocardial perfusion imaging using technitium-99m sestamibi in suspected coronary artery disease: A single-center experience of 1,047 patients
Introduction: The aim of the present study was to evaluate the clinical outcome of a normal stress technetium-99m (99mTc)-Sestamibi single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with different probabilities of coronary artery disease (CAD). Material and Methods: A total of 1,047 subjects with a normal 99mTc-MIBI SPECT were followed up for one year and hard and soft cardiac events were assessed. Hard cardiac events were defined as cardiac death or non-fatal myocardial infarction (MI). Soft cardiac events included the patient's development of recurrent chest pain requiring coronary revascularization or significant stenosis in coronary arteries on angiography. Results: Overall, 1,047 patients (248 men and 799 women; mean age: 60.07 ± 12.31, range 29-92) were enrolled. Three hard cardiac events occurred in the groups; two had cardiac arrest and one non-fatal MI. As a result, the annualized hard cardiac event rate was 0.28%, the annualized cardiac mortality rate was 0.19%, and the rate of overall annualized cardiac events was 1.25%. Furthermore, there was a significant difference in cardiac events among patients with various pretest likelihoods of CAD (p value=0.04). Conclusion: Our data confirmed that patients with a normal 99mTc-Sestamibi myocardial SPECT are associated with a very low incidence of cardiovascular events. © The Author(s) 2011
How climate change has affected the spatio-temporal patterns of precipitation and temperature at various time scales in North Korea
Detecting changes in the spatio-temporal patterns of temperature and precipitation is a prerequisite for developing effective adaptation options and strategies for the future. An effective method for assessing climate change and for providing information to decision makers and stakeholders is needed to implement appropriate adaptation strategies. The objective of this study was to determine whether climate change has caused spatio-temporal changes in meteorological elements in North Korea. We delineated the spatio-temporal patterns of temperature and precipitation caused by climate change in specific time periods based on statistically significant differences using a statistically robust method. Historical weather data from 27 meteorological stations over a 30-year period (1981–2010) were used. The results demonstrated that statistically significant changes occurred over the 30 years. The temporal trends in the maximum and minimum temperatures were highly significantly different in the western agricultural regions and central/southwest urban regions during 1996–2010 compared with 1981–1995. The precipitation amounts were significantly different in the southeast regions (around the coast). The numbers of precipitation events were significantly different for portions of the northern and northeast areas near the mountains. Additionally, statistically significant differences in the spatial structures of the temperature and precipitation were found at different time scales. The significant differences were not uniform in each season/month. Therefore, significant differences occurred in the meteorological elements, and particular locations and urbanized areas were affected by global warming. However, the temporal trends and spatial structures of each meteorological element were not equally modified; the meteorological changes occurred locally as a result of the changing climate
Spatial patterns and temporal variability of drought in Western Iran
An analysis of drought in western Iran from 1966 to 2000 is presented
using monthly precipitation data observed at 140 gauges uniformly distributed over
the area. Drought conditions have been assessed by means of the Standardized
Precipitation Index (SPI). To study the long-term drought variability the principal
component analysis was applied to the SPI field computed on 12-month time scale.
The analysis shows that applying an orthogonal rotation to the first two principal
component patterns, two distinct sub-regions having different climatic variability
may be identified. Results have been compared to those obtained for the largescale
using re-analysis data suggesting a satisfactory agreement. Furthermore, the
extension of the large-scale analysis to a longer period (1948–2007) shows that
the spatial patterns and the associated time variability of drought are subjected
to noticeable changes. Finally, the relationship between hydrological droughts in
the two sub-regions and El Niño Southern Oscillation events has been investigated
finding that there is not clear evidence for a link between the two phenomen
- …