scholarly journals Estimating Soil Wetness from the GOES Sounder

2006 ◽  
Vol 23 (7) ◽  
pp. 991-1003 ◽  
Author(s):  
Robert M. Rabin ◽  
Timothy J. Schmit
Keyword(s):  
United States ◽  
Soil Moisture ◽  
High Temperature ◽  
Satellite Data ◽  
Temperature Rise ◽  
Clear Sky ◽  
Average Temperature ◽  
Radiative Temperature ◽  
The Relationship ◽  
High Temperature Rise

Abstract In this note, the relationship between the observed daytime rise in surface radiative temperature, derived from the Geostationary Operational Environmental Satellites (GOES) sounder clear-sky data, and modeled soil moisture is explored over the continental United States. The motivation is to provide an infrared (IR) satellite–based index for soil moisture, which has a higher resolution than possible with the microwave satellite data. The daytime temperature rise is negatively correlated with soil moisture in most areas. Anomalies in soil moisture and daytime temperature rise are also negatively correlated on monthly time scales. However, a number of exceptions to this correlation exist, particularly in the western states. In addition to soil moisture, the capacity of vegetation to generate evapotranspiration influences the amount of daytime temperature rise as sensed by the satellite. In general, regions of fair to poor vegetation health correspond to the relatively high temperature rise from the satellite. Regions of favorable vegetation match locations of lower-than-average temperature rise.

scholarly journals Flow Characteristics of a Rich-Quench-Lean Combustor-Combined Low-Emission and High-Temperature Rise Combustion

2019 ◽  
Vol 2019 ◽  
pp. 1-22
Author(s):  
Jianzhong Li ◽  
Jian Chen ◽  
Li Yuan ◽  
Ge Hu ◽  
Jianhan Feng
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
Residence Time ◽  
Temperature Rise ◽  
Recirculation Zone ◽  
Flow Characteristics ◽  
Field Structure ◽  
Low Emission ◽  
The Rich ◽  
High Temperature Rise

To determine the flow field structure and flow characteristics of a rich-quench-lean (RQL) combustor-combined low-emission and high-temperature rise combustion, a two-dimensional PIV technology was used to evaluate the effect of aerodynamic and structural parameters on the flow field and flow characteristics of the combustor. The variation in the total pressure loss of the combustor has little effect on the flow field structure of the combustor. However, the variation in the parameters of primary holes significantly affects the structure of the central recirculation zone, the distribution of local recirculation zones in the rich-burn zone and quenching zone, and the average residence time in the quenching zone. On the plane that passes through the center of the primary hole, the variations in the array mode and diameter of primary holes would form entrainment vortexes with different characteristics, thus affecting the position and flow state of local recirculation in the rich-burn zone and the local structure of the central recirculation zone. As the rotational direction of local recirculation coincides with that of the main air flow in the primary zone, the local center recirculation is intensified. In contrast, it is weakened. As the primary holes are located at half height (H/2) of the combustor, the residence time of air flow at the quenching zone can be shortened by 65% through using the staggered structure of primary holes and increasing the momentum of the partial single-hole jet. The quick-mixing process in the quenching zone is not beneficial to increase the number of primary holes and decrease the momentum of the single-hole jet.

Design Procedure of a Reverse Flow Combustor for a Helicopter Engine with High Temperature Rise

2011 ◽  
Author(s):  
Bhupendra Khandelwal ◽  
Mingchao Yan ◽  
Gajanana Hegde ◽  
Vishal Sethi ◽  
Riti Singh
Keyword(s):  
High Temperature ◽  
Temperature Rise ◽  
Reverse Flow ◽  
Design Procedure ◽  
High Temperature Rise

Prediction of Flash Droughts over the United States

2020 ◽  
Vol 21 (8) ◽  
pp. 1793-1810
Author(s):  
Kingtse C. Mo ◽  
Dennis P Lettenmaier
Keyword(s):  
United States ◽  
Soil Moisture ◽  
High Temperature ◽  
Pacific Northwest ◽  
Heat Wave ◽  
Late Summer ◽  
The United States ◽  
Late Spring ◽  
The North ◽  
June July

AbstractWe examine reforecasts of flash droughts over the United States for the late spring (April–May), midsummer (June–July), and late summer/early autumn (August–September) with lead times up to 3 pentads based on the NOAA second-generation Global Ensemble Forecast System reforecasts version 2 (GEFSv2). We consider forecasts of both heat wave and precipitation deficit (P deficit) flash droughts, where heat wave flash droughts are characterized by high temperature and depletion of soil moisture and P deficit flash droughts are caused by lack of precipitation that leads to (rather than being the cause of) high temperature. We find that the GEFSv2 reforecasts generally capture the frequency of occurrence (FOC) patterns. The equitable threat score (ETS) of heat wave flash drought forecasts for late spring in the regions where heat wave flash droughts are most likely to occur over the north-central and Pacific Northwest regions is statistically significant up to 2 pentads. The GEFSv2 reforecasts capture the basic pattern of the FOC of P-deficit flash droughts and also are skillful up to lead about 2 pentads. However, the reforecasts overestimate the P-deficit flash drought FOC over parts of the Southwest in late spring, leading to large false alarm rates. For autumn, the reforecasts underestimate P-deficit flash drought occurrence over California and Nevada. The GEFSv2 reforecasts are able to capture the approximately linear relationship between evaporation and soil moisture, but the lack of skill in precipitation forecasts limits the skill of P-deficit flash drought forecasts.

The Relationship between Cool and Warm Season Moisture over the Central United States, 1685–2015

2018 ◽  
Vol 31 (19) ◽  
pp. 7909-7924 ◽  
Author(s):  
Max C. A. Torbenson ◽  
David W. Stahle
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Tree Ring ◽  
Land Surface ◽  
Warm Season ◽  
Instrumental Record ◽  
Moisture Balance ◽  
Central United States ◽  
The Relationship

Land surface feedbacks impart a significant degree of persistence between cool and warm season moisture availability in the central United States. However, the degree of correlation between these two variables is subject to major changes that appear to occur on decadal to multidecadal time scales, even in the relatively short 115-yr instrumental record. Tree-ring reconstructions have extended the limited observational record of long-term soil moisture levels, but such reconstructions do not resolve the seasonal differences in moisture conditions. We present two separate 331-yr-long seasonal moisture reconstructions for the central United States, based on sensitive subannual and annual tree-ring chronologies that have strong and separate seasonal moisture signals: an estimate of the long-term May soil moisture balance and a second estimate of the short-term June–August atmospheric moisture balance. The predictors used in each seasonal reconstruction are not significantly correlated with the alternate season target. Both reconstructions capture over 70% of the interannual variance in the instrumental data for the calibration period and also share significant decadal and multidecadal variability with the instrumental record in both the calibration and validation periods. The instrumental and reconstructed moisture levels are both positively correlated between spring and summer strongly enough to have potential value in seasonal prediction. However, the relationship between spring and summer moisture exhibits major decadal changes in strength and even sign that appear to be related to large-scale ocean–atmosphere dynamics associated with the Atlantic multidecadal oscillation.

Flow and flame characteristics of a RP-3 fuelled high temperature rise combustor based on RQL

Fuel ◽  
2019 ◽  
Vol 235 ◽  
pp. 1159-1171 ◽  
Author(s):  
Jian Chen ◽  
Jianzhong Li ◽  
Li Yuan ◽  
Ge Hu
Keyword(s):  
High Temperature ◽  
Temperature Rise ◽  
High Temperature Rise

scholarly journals Ecosystem functional response across precipitation extremes in a sagebrush steppe

2017 ◽  
Author(s):  
Andrew T. Tredennick ◽  
Andrew R. Kleinhesselink ◽  
J. Bret Taylor ◽  
Peter B. Adler
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Functional Response ◽  
Community Composition ◽  
Plant Community ◽  
Extreme Precipitation ◽  
Sagebrush Steppe ◽  
Functional Responses ◽  
The Relationship

ABSTRACTBackgroundPrecipitation is predicted to become more variable in the western United States, meaning years of above and below average precipitation will become more common. Periods of extreme precipitation are major drivers of interannual variability in ecosystem functioning in water limited communities, but how ecosystems respond to these extremes over the long-term may shift with precipitation means and variances. Long-term changes in ecosystem functional response could reflect compensatory changes in species composition or species reaching physiological thresholds at extreme precipitation levels.MethodsWe conducted a five year precipitation manipulation experiment in a sagebrush steppe ecosystem in Idaho, United States. We used drought and irrigation treatments (approximately 50% decrease/increase) to investigate whether ecosystem functional response remains consistent under sustained high or low precipitation. We recorded data on aboveground net primary productivity (ANPP), species abundance, and soil moisture. We fit a generalized linear mixed effects model to determine if the relationship between ANPP and soil moisture differed among treatments. We used nonmetric multidimensional scaling to quantify community composition over the five years.ResultsEcosystem functional response, defined as the relationship between soil moisture and ANPP, was similar among irrigation and control treatments, but the drought treatment had a greater slope than the control treatment. However, all estimates for the effect of soil moisture on ANPP overlapped zero, indicating the relationship is weak and uncertain regardless of treatment. There was also large spatial variation in ANPP within-years, which contributes to the uncertainty of the soil moisture effect. Plant community composition was remarkably stable over the course of the experiment and did not differ among treatments.DiscussionDespite some evidence that ecosystem functional response became more sensitive under sustained drought conditions, the response of ANPP to soil moisture was consistently weak and community composition was stable. The similarity of ecosystem functional responses across treatments was not related to compensatory shifts at the plant community level, but instead may reflect the insensitivity of the dominant species to soil moisture. These species may be successful precisely because they have evolved life history strategies which buffer them against precipitation variability.

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