scholarly journals Concurrent and lagged relationships among various drought indices in the United states

MAUSAM ◽  
2021 ◽  
Vol 43 (1) ◽  
pp. 43-50
Author(s):  
PETER T. SOULE
Keyword(s):  
United States ◽  
Supply And Demand ◽  
Severity Index ◽  
Fast Response ◽  
The United States ◽  
Drought Indices ◽  
Drought Severity ◽  
Strongly Correlated ◽  
Entire Study ◽  
Hydrologic Drought

The purpose of this study is to examine the nature of the concurrent and lagged relationships among various drought type-specific measures of drought severity. Monthly values of average temperature (TEMPZ), total precipitation (PREZ), the Palmer moisture anomaly index (ZINX)  the Palmer drought severity index  (PDSl), and the Palmer hydrologic drought seventy Index (PHDI) were examined  from a sample of climatic divisions, in the United States for the period,1931-1985. The relationships are examined at two levels through the use of simple correlations. Level one utilizes data from the entire study period. Data from selected drought   events are employed in level two.   The results show that the strongest relationships are between drought indices with similar rates of response to changes in moisture supply and demand. The correlations also show that lagged values of fast-response drought indices (ZINX, PREZ) arc more strongly correlated with the slow-response PHD1 than concurrent values. Intersite differences between correlated pairs of indices are generally small and follow consistent trends; cross the flow pattern sample for both level one and level two analyses. Intra-site differences are large for some pairs of correlated indices indicating that characteristics of individual droughts can deviate substantially from average or normal conditions

scholarly journals Adaptation of Irrigation Infrastructure on Irrigation Demands under Future Drought in the United States*

2015 ◽  
Vol 19 (7) ◽  
pp. 1-16 ◽  
Author(s):  
Tianyi Zhang ◽  
Xiaomao Lin ◽  
Danny H. Rogers ◽  
Freddie R. Lamm
Keyword(s):  
United States ◽  
Irrigation Water ◽  
Severity Index ◽  
The United States ◽  
Drought Severity ◽  
Severe Drought ◽  
Surface Irrigation ◽  
Irrigation Depth ◽  
Unit Reduction ◽  
Irrigation Infrastructure

Abstract More severe droughts in the United States will bring great challenges to irrigation water supply. Here, the authors assessed the potential adaptive effects of irrigation infrastructure under present and more extensive droughts. Based on data over 1985–2005, this study established a statistical model that suggests around 4.4% more irrigation was applied in response to a one-unit reduction in the Palmer drought severity index (PDSI), and approximately 5.0% of irrigation water application could be saved for each 10% decrease in the areas supplied by surface irrigation infrastructure. Based on the results, the model-projected irrigation infrastructure has played a greater role in changes in irrigation than drought in most areas under the current climate except some southwestern counties. However, under the predicted future more severe drought in 2080–99 under the representative concentration pathways 4.5 scenario, the model projected that the drought will require 0%–20% greater irrigation amounts assuming the current irrigation efficiency. Under the predicted drought scenario, irrigation depth can be maintained at or below the baseline level in the western United States only when better irrigation infrastructure replaced 40% of the current surface irrigation infrastructure areas. In the northeast United States, limited changes in irrigation depth were predicted under different irrigation infrastructure scenarios because the percentage of surface irrigation area is already low under the baseline climate, and thus there is limited opportunity to adapt to future drought with advanced irrigation infrastructure. These results indicate that other effective solutions are required to complement these measures and aid U.S. agriculture in the future, more extensive drought.

scholarly journals Tracking Interannual Streamflow Variability with Drought Indices in the U.S. Pacific Northwest

2014 ◽  
Vol 15 (5) ◽  
pp. 1900-1912 ◽  
Author(s):  
John T. Abatzoglou ◽  
Renaud Barbero ◽  
Jacob W. Wolf ◽  
Zachary A. Holden
Keyword(s):  
Pacific Northwest ◽  
Potential Evapotranspiration ◽  
Standardized Precipitation Index ◽  
Severity Index ◽  
The United States ◽  
Drought Indices ◽  
Drought Severity ◽  
Climate Data ◽  
Mountain Watersheds ◽  
Streamflow Variability

Abstract Drought indices are often used for monitoring interannual variability in macroscale hydrology. However, the diversity of drought indices raises several issues: 1) which indices perform best and where; 2) does the incorporation of potential evapotranspiration (PET) in indices strengthen relationships, and how sensitive is the choice of PET methods to such results; 3) what additional value is added by using higher-spatial-resolution gridded climate layers; and 4) how have observed relationships changed through time. Standardized precipitation index, standardized precipitation evapotranspiration index (SPEI), Palmer drought severity index, and water balance runoff (WBR) model output were correlated to water-year runoff for 21 unregulated drainage basins in the Pacific Northwest of the United States. SPEI and WBR with time scales encompassing the primary precipitation season maximized the explained variance in water-year runoff in most basins. Slightly stronger correlations were found using PET estimates from the Penman–Monteith method over the Thornthwaite method, particularly for time periods that incorporated the spring and summer months in basins that receive appreciable precipitation during the growing season. Indices computed using high-resolution climate surfaces explained over 10% more variability than metrics derived from coarser-resolution datasets. Increased correlation in the latter half of the study period was partially attributable to increased streamflow variability in recent decades as well as to improved climate data quality across the interior mountain watersheds.

scholarly journals Stochastically Generated North American Megadroughts

2015 ◽  
Vol 28 (5) ◽  
pp. 1865-1880 ◽  
Author(s):  
Samantha Stevenson ◽  
Axel Timmermann ◽  
Yoshimitsu Chikamoto ◽  
Sally Langford ◽  
Pedro DiNezio
Keyword(s):  
United States ◽  
North American ◽  
Land Surface ◽  
Severity Index ◽  
The United States ◽  
Dominant Factor ◽  
Drought Severity ◽  
The North ◽  
Sst Forcing ◽  
Sst Anomalies

Abstract The importance of interannual-to-decadal sea surface temperature (SST) influences on drought in the United States is examined using a suite of simulations conducted with the T31×3 resolution version of the NCAR Community Earth System Model (CESM1.0.3). The model captures tropical Pacific teleconnections to North American precipitation reasonably well, although orographic features are somewhat enhanced at higher resolution. The contribution of SST anomalies is isolated by comparing two idealized, 1000-yr CESM1.0.3 experiments: a fully coupled control and an atmosphere-only (CAM4) run forced with the SST climatology from the control. Droughts are identified using the Palmer Drought Severity Index (PDSI), which is computed over four U.S. regions from the CESM1.0.3 experiments and compared with the North American Drought Atlas (NADA). The CESM1.0.3 reproduces the persistence of NADA droughts quite well, although the model underestimates drought severity. Within the CESM1.0.3 framework, SST forcing does not significantly affect drought intensity or frequency of occurrence, even for very persistent “megadroughts” of 15 yr or more in length. In both the CESM1.0.3 and NADA, with the exception of the Southeast United States, droughts in all regions have intensities, persistence lengths, and occurrence frequencies statistically consistent with a red noise null hypothesis. This implies that SST forcing is not the dominant factor in generating drought and therefore that many decadal megadroughts are caused by a combination of internal atmospheric variability and coupling with the land surface, with SST anomalies playing only a secondary role.

scholarly journals Evidence for Increasingly Variable Drought Conditions in the United States Since 1895

2015 ◽  
Author(s):  
Sierra Rayne ◽  
Kaya Forest
Keyword(s):  
United States ◽  
Severity Index ◽  
The United States ◽  
Time Frame ◽  
Drought Severity ◽  
The Pacific ◽  
Rapid Changes ◽  
Increasing Trend ◽  
End Members ◽  
Short Time

Annual and summertime trends towards increasingly variable values of the Palmer Drought Severity Index (PDSI) over a sub-decadal period (five years) were investigated within the contiguous United States between 1895 and the present. For the contiguous U.S. as a whole, there is a significant increasing trend in the five-year running minimum-maximum ranges for the annual PDSI (aPDSI5yr(min|max range)). During this time frame, the averageaPDSI5yr(min|max range)has increased by about one full unit, indicating a substantial increase is drought variability over short time scales across the United States. The end members of the runningaPDSI5yr(min|max range)highlight even more rapid changes in the drought index variability within the past 120 years. This increasing variability in theaPDSI5yr(min|max range)is driven primarily by changes taking place in the Pacific and Atlantic Ocean coastal climate regions, climate regions which collectively comprise one-third the area of the contiguous U.S. Overall, interannual drought patterns are becoming more extreme and difficult to predict, posing a challenge to agricultural and other water-resource related planning efforts.

scholarly journals Spatial–Temporal Patterns of Historical, Near-Term, and Projected Drought in the Conterminous United States

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 136
Author(s):  
Susan M. Kotikot ◽  
Olufemi A. Omitaomu
Keyword(s):  
United States ◽  
Spatial Scale ◽  
Climate Models ◽  
Global Climate ◽  
Severity Index ◽  
The United States ◽  
Global Climate Models ◽  
Drought Severity ◽  
Near Term ◽  
Local Variability

Major droughts in the United States have heavily impacted the hydrologic system, negatively effecting energy and food production. Improved understanding of historical drought is critical for accurate forecasts. Data from global climate models (GCMs), commonly used to assess drought, cannot effectively evaluate local patterns because of their low spatial scale. This research leverages downscaled (~4 km grid spacing) temperature and precipitation estimates from nine GCMs’ data under the business-as-usual scenario (Representative Concentration Pathway 8.5) to examine drought patterns. Drought severity is estimated using the Palmer Drought Severity Index (PDSI) with the Thornthwaite evapotranspiration method. The specific objectives were (1) To reproduce historical (1966–2005) drought and calculate near-term to future (2011–2050) drought patterns over the conterminous USA. (2) To uncover the local variability of spatial drought patterns in California between 2012 and 2018 using a network-based approach. Our estimates of land proportions affected by drought agree with the known historical drought events of the mid-1960s, late 1970s to early 1980s, early 2000s, and between 2012 and 2015. Network analysis showed heterogeneity in spatial drought patterns in California, indicating local variability of drought occurrence. The high spatial scale at which the analysis was performed allowed us to uncover significant local differences in drought patterns. This is critical for highlighting possible weak systems that could inform adaptation strategies such as in the energy and agricultural sectors.

scholarly journals Supply and Demand for Radiation Oncology in the United States: Updated Projections for 2015 to 2025

2016 ◽  
Vol 96 (2) ◽  
pp. E394-E395
Author(s):  
H.Y. Pan ◽  
B.G. Haffty ◽  
B. Falit ◽  
T.A. Buchholz ◽  
L.D. Wilson ◽  
...  
Keyword(s):  
United States ◽  
Radiation Oncology ◽  
Supply And Demand ◽  
The United States

scholarly journals Effects of different reference periods on drought index (SPEI) estimations from 1901 to 2014

2017 ◽  
Vol 21 (10) ◽  
pp. 4989-5007 ◽  
Author(s):  
Myoung-Jin Um ◽  
Yeonjoo Kim ◽  
Daeryong Park ◽  
Jeongbin Kim
Keyword(s):  
West Africa ◽  
East Asia ◽  
The United States ◽  
Spatial Extent ◽  
Drought Indices ◽  
Drought Severity ◽  
Climate Change Scenarios ◽  
Reference Period ◽  
Drought Characteristics ◽  
Regional Drought

Abstract. This study aims to understand how different reference periods (i.e., calibration periods) of climate data used to estimate drought indices influence regional drought assessments. Specifically, we investigate the influences of different reference periods on historical drought characteristics, such as the trend, frequency, intensity and spatial extent, using the standardized precipitation evapotranspiration index (SPEI) with a 12-month lag (SPEI-12), which was estimated from the datasets of the Climate Research Unit (CRU) and the University of Delaware (UDEL). For the 1901–1957 (P1) and 1958–2014 (P2) estimation periods, three different types of reference periods are used to compute the SPEI: P1 and P2 together, P1 and P2 separately and P1 only. Focusing on East Asia, Europe, the United States and West Africa, we find that the influence of the reference period is significant in East Asia and West Africa, with dominant drying trends from P1 to P2. The reference period influenced the assessment of drought characteristics, particularly the severity and spatial extent, whereas the influence on the frequency was relatively small. Finally, self-calibration, which is the most common practice for indices such as the SPEI, tends to underestimate the drought severity and spatial extent relative to the other approaches used in this study. Although the conclusions drawn in this study are limited by the use of two global datasets, they highlight the need for clarification of the reference period in drought assessments to better understand regional drought characteristics and the associated temporal changes, particularly under climate change scenarios.

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