precipitation record
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Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 233
Author(s):  
Elia M. Tapia-Villaseñor ◽  
Eylon Shamir ◽  
Mary-Belle Cruz-Ayala ◽  
Sharon B. Megdal

The impact of climate uncertainties is already evident in the border communities of the United States and Mexico. This semi-arid to arid border region has faced increased vulnerability to water scarcity, propelled by droughts, warming atmosphere, population growth, ecosystem sensitivity, and institutional asymmetries between the two countries. In this study, we assessed the annual water withdrawal, which is essential for maintaining long-term sustainable conditions in the Santa Cruz River Aquifer in Mexico, which is part of the U.S.–Mexico Transboundary Santa Cruz Aquifer. For this assessment, we developed a water balance model that accounts for the water fluxes into and out of the aquifer’s basin. A central component of this model is a hydrologic model that uses precipitation and evapotranspiration demand as input to simulate the streamflow into and out of the basin, natural recharge, soil moisture, and actual evapotranspiration. Based on the precipitation record for the period 1954–2020, we found that the amount of groundwater withdrawal that maintains sustainable conditions is 23.3 MCM/year. However, the record is clearly divided into two periods: a wet period, 1965–1993, in which the cumulative surplus in the basin reached ~380 MCM by 1993, and a dry period, 1994–2020, in which the cumulative surplus had been completely depleted. Looking at a balanced annual groundwater withdrawal for a moving average of 20-year intervals, we found the sustainable groundwater withdrawal to decline from a maximum of 36.4 MCM/year in 1993 to less than 8 MCM/year in 2020. This study underscores the urgency for adjusted water resources management that considers the large inter-annual climate variability in the region.


2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Takuya Itaki ◽  
Sakura Utsuki ◽  
Yuki Haneda ◽  
Kentaro Izumi ◽  
Yoshimi Kubota ◽  
...  

AbstractMarine isotope stage (MIS) 19 is considered to be the best orbital analog for the present interglacial. Consequently, clarifying the climatic features of this period can provide us with insights regarding a natural baseline for assessing future climate changes. A high-resolution radiolarian record from 800 to 750 ka (MIS 20 to MIS 18) was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the Global Boundary Stratotype Section and Point for the lower–middle Pleistocene boundary on the Boso Peninsula on the Pacific side of central Japan. Millennial-scale oscillations in the Kuroshio warm and Oyashio cold currents were revealed by the Tr index, which is estimated using a simple equation based on radiolarian assemblages. The estimated Tr values ranged between 0.1 and 0.8 for MIS 18 through MIS 19, with minimum and maximum values corresponding to values observed off present day Aomori (41°N) and the Boso Peninsula (35°N), respectively. The observed patterns tended to be synchronous with the total radiolarian abundance associated with their production. Multiple maxima in radiolarian abundance occurred during periods of the Oyashio expanded mode before 785 ka and during periods of Kuroshio extension after 785 ka in MIS 19. Such increases in radiolarian abundance with the Kuroshio extension during MIS 19 are likely related to improvements in nutrient and photic environments with the development of a two-layer structure along the Kuroshio–Oyashio boundary zone. A similar pattern of millennial-scale climatic changes was also recognized in a precipitation record from the Sulmona Basin in central Italy, suggesting a close relationship with the CbCS record as a result of a large-scale climate system similar to the Arctic Oscillation in the northern hemisphere.


Author(s):  
Nathaniel Parker ◽  
Andres Patrignani

Abstract Complete and accurate precipitation records are important for developing reliable flood warning systems, streamflow forecasts, rainfall-runoff estimates, and numerical land surface predictions. Existing methods for flagging missing precipitation events and filling gaps in the precipitation record typically rely on precipitation from neighboring stations. In this study, we investigated an alternative method for back-calculating precipitation events using changes in rootzone soil water storage. Our hypothesis was that using a different variable (i.e., soil moisture) from the same monitoring station will be more accurate in estimating hourly precipitation than using the same variable (i.e., precipitation) from the nearest neighboring station. Precipitation events were estimated from soil moisture as the sum of hourly changes in profile soil water storage. Hourly precipitation and soil moisture observations were obtained for a mesoscale network in the central U.S. Great Plains from May 2017 to December 2020. The proposed method based on soil moisture had a minimum detectable limit of 7.6 mm (95th percentile of undetected precipitation events) due to canopy and soil interception. The method was outperformed by the nearest neighbor (NN) interpolation method when neighboring stations were at distances of <10 km. However, the proposed method outperformed the NN method in 22 out of 27 stations when nearest stations were at distances >10 km. Using changes in soil water storage resulted effective in flagging and reconstructing actual missing precipitation events caused by pluviometer malfunction, highlighting new opportunities for using readily available in situ soil moisture information for operational quality control in mesoscale environmental monitoring networks.


2021 ◽  
Author(s):  
Malte Muller ◽  
Timo Kelder ◽  
Cyril Palerme

Extreme precipitation over the Svalbard Archipelago in the Arctic can have severe consequences for the ecosystem and society. In recent years several extreme precipitation events have been observed at Ny Ålesund, a weather station in the north-western part of the Svalbard Archipelago. The most recent observed events in the years 2012, 2016, and 2018 were the highest events in the entire precipitation record from 1974 till today. The key question of our study is whether those recently observed extremes are part of a climate change signal or are a random accumulation of extremes. With a novel approach based on a large ensemble of model simulations, we show that the likelihood of occurrence for extreme precipitation over Svalbard has increased over the last four decades. We find that the likelihood of occurrence is connected to the sea ice extent east of Greenland because the presence of sea ice shields the west coast of Svalbard from the incoming southerly moist air. Our analysis suggests, that in the future with a further decline of the sea ice coverage east of Greenland, the recently observed precipitation extremes will become even more frequent.


Author(s):  
Sean R. Scott ◽  
Jason P. Dunion ◽  
Mark L. Olson ◽  
David A. Gay

AbstractAtmospheric dust is an important mass transfer and nutrient supply process in Earth surface ecosystems. For decades, Saharan Dust has been hypothesized as a supplier of nutrients to the Amazon Rain Forest and Eastern North America. However, isotope studies aimed at detecting Saharan dust in the American sedimentary record have been ambiguous. A large Saharan dust storm emerged off the coast of Africa in June 2020 and extended into southeastern United States. This storm provided a means to evaluate the influence of Saharan dust in North America confirmed by independent satellite and ground observations. Precipitation samples from 17 sites within the National Atmospheric Deposition Program (NADP) were obtained from throughout the southeastern United States prior to, during, and after the arrival of Saharan dust. Precipitation samples were measured for their lead (Pb) isotopic composition, total Pb content, and 210Pb activity using multi-collector inductively coupled plasma mass spectrometry. We measured a significant isotopic shift (approximately 0.7 % in the 208Pb/206Pb relative to the 207Pb/206Pb) in precipitation that peaked in late June 2020 when the dust blanketed the southeastern US. However, the magnitude and short time period of the isotopic shift would make it difficult to detect in sedimentary records.


2021 ◽  
Author(s):  
Christophe Kinnard ◽  
Olivier Larouche ◽  
Michael N. Demuth ◽  
Brian Menounos

Abstract. Glacier mass balance models are needed at sites with scarce long-term observations to reconstruct past glacier mass balance and assess its sensitivity to future climate change. In this study North American Regional Reanalysis (NARR) data are used to force a physically-based, distributed glacier mass balance model of Saskatchewan Glacier for the historical period 1979–2016 and assess it sensitivity to climate change. A two-year record (2014–2016) from an on-glacier automatic weather station (AWS) and a homogenized historical precipitation record from nearby permanent weather stations were used to downscale air temperature, relative humidity, wind speed, incoming solar radiation and precipitation from the nearest NARR gridpoint to the glacier AWS site. The model was run with fixed (1979, 2010) and time-varying (dynamic) geometry using a multi-temporal digital elevation model (DEM) dataset. The model showed a good performance against recent (2012–2016) direct glaciological mass balance observations as well as with cumulative geodetic mass balance estimates. The simulated mass balance showed a large sensitivity to the biases in NARR precipitation and solar radiation, as well as to the prescribed precipitation lapse rate and ice aerodynamic roughness lengths, showing the importance of constraining these parameters with ancillary data. The difference between the static (1979) and dynamic simulations showed small differences (mean = 0.06 m w.e. a−1 or 1.5 m w.e. over 37 yrs), indicating minor effects of elevation changes on the glacier specific mass balance. The static mass balance sensitivity to climate was assessed for prescribed changes in regional mean air temperature between 0 to 7 °C and precipitation between −20 to +20 %, which comprise the spread of ensemble IPCC representative concentration pathways climate scenarios for the mid (2041–2070) and late (2071–2100) 21st century. The climate sensitivity experiments showed that future changes in precipitation would have a small impact on glacier mass-balance, while the temperature sensitivity increases with warming, from −0.65 to −0.93 m w.e. °C−1. Increased melting accounted for 90 % of the temperature sensitivity while precipitation phase feedbacks accounted for only 10 %. Roughly half of the melt response to warming was driven by a positive albedo feedback, in which glacier albedo decreases as the snow cover on the glacier thins and recedes earlier in response to warming, increasing net solar radiation fluxes. About one quarter of the melt response to warming was driven by latent heat energy gains (positive humidity feedback). Our study underlines the key role of albedo and air humidity in modulating the response of winter-accumulation type mountain glaciers and upland icefield-outlet glacier settings to climate.


2021 ◽  
Author(s):  
Zeynab Foroozan ◽  
Jussi Grießinger ◽  
Kambiz Pourtahmasi ◽  
Achim Bräuning

&lt;p&gt;Knowledge about the long-term hydroclimatic variability is essential to analyze the historic course and recent impact of climate change, especially in semi-arid and arid regions of the world. In this study, we present the first tree-ring &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O chronology for the semi-arid parts of northern Iran based on juniper trees. We were able to reconstruct past hydroclimatic variability for the past 500 years. The highly significant correlation between tree-ring &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and spring precipitation indicates the primary influence of spring moisture availability on &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O variations. The thereof derived precipitation reconstruction reveals short and long-term variability of precipitation intensity, duration, and frequency of dry/wet events. During the past 500 years, the driest period occurred in the 16&lt;sup&gt;th&lt;/sup&gt; century, whereas the 18th century was comparably wet. A gradual decline in the reconstructed spring precipitation is evident since the beginning of the 19th century, culminating in the continuing drought of the 20&lt;sup&gt;th&lt;/sup&gt; century. An analysis of dry/wet years indicated that over the last three centuries, the occurrence of years with a relatively dry spring is increasing. In contrast, more humid spring conditions are decreasing. However, the overall frequency of the occurrence of extreme events increased over the past five centuries. In addition, past hydrological disasters recorded in Persian history were well represented in our reconstruction. Correlations between our reconstructed precipitation record and large-scale circulation systems revealed no significant influence of large-scale climatic drivers on spring precipitation variations in north Iran, which therefore seem to be mostly controlled by a regional climate forcing.&lt;/p&gt;


2021 ◽  
Author(s):  
Hansheng Wang ◽  
Junsheng Nie ◽  
Zeng Luo

&lt;p&gt;3.6 Ma represents a time period when Earth transitioned from single pole ice sheets to permanent ice sheets existing in both hemispheres. However, it remains unclear how this transition had its impact on East Asian summer monsoon system, which controls living of a large population. Here, we present a high-resolution (2~4 kyr) monsoon precipitation record from the Chaona section on the central Chinese Loess Plateau during the 3.95-2.95 Ma, using the magnetic parameter-based precipitation proxy (&amp;#967;fd/HIRM). The results reveal intensified precessional and semiprecessional fluctuations during high eccentricity, emphasizing direction role of low latitude insolation played in forcing Asian monsoon precipitation. The precipitation records also show that the 41-kyr cycles intensified after 3.3 Ma, in contrast with decreased obliquity variation amplitude of summer insolation. We interpret the enlarged 41-kyr precipitation cycles in our records as a result of high latitude ice sheet forcing. Together, our work provides an example demonstrating both high and low latitude forcing of Asian monsoon precipitation during the late Pliocene.&lt;/p&gt;


2021 ◽  
Author(s):  
Daniel Watters ◽  
Alessandro Battaglia ◽  
Richard Allan

&lt;p&gt;Simulations of the diurnal cycle of precipitation from CMIP6 models and the ERA5 reanalysis are evaluated against the observed diurnal cycle from NASA&amp;#8217;s IMERG observations.&amp;#160; The IMERG observation product, which combines the GPM/TRMM microwave constellation, spaceborne infrared sensors and ground-based gauge measurements, provides 20+ years of gridded global precipitation estimates at 0.1&amp;#730; every half hour.&amp;#160; Using IMERG&amp;#8217;s long precipitation record, the first multi-decade evaluation of the simulated diurnal cycle is conducted (IMERG and ERA5: 2000-2019; CMIP6: 1979-2008).&amp;#160; After spatial and temporal matching of IMERG to the hourly CMIP6 (NCAR-CESM2, CNRM-CM6-1, CNRM-ESM2-1) and ERA5 simulations, the diurnal cycle for boreal summer is compared between products across the globe (60&amp;#730;N-S).&amp;#160; To avoid bias in the results, regions with yearly mean precipitation &lt; 100 mm are excluded from all analyses, as well as regions with weak diurnal amplitudes when analysing the time of maximum precipitation.&amp;#160; CMIP6 and ERA5 simulations underestimate the observed diurnal amplitude over ocean (14-66% of the precipitation mean, for the 5&lt;sup&gt;th&lt;/sup&gt;-95&lt;sup&gt;th&lt;/sup&gt; percentile range), with varying performance over land (26-134%).&amp;#160; Maximum precipitation is observed to accumulate over land in the afternoon and at night (14-21 LST over flatter terrain, and 21-6 LST over mountainous regions), and in the morning over ocean (0-12 LST).&amp;#160; CMIP6 and ERA5 are identified to better simulate the time of maximum over ocean than over land, though typically earlier in the day than observed.&amp;#160; In particular, ERA5 and CMIP6 fail to capture the propagating night-time peaks in precipitation accumulation close to mountainous regions.&amp;#160; Further analyses over CONUS, which include the ground-based radar network, highlight the improved performance of models in regions susceptible to convection (e.g. the Rocky Mountains).&amp;#160; Furthermore, IMERG&amp;#8217;s skill in capturing the diurnal cycle over CONUS is demonstrated, and the current capability of the GPM Core Observatory&amp;#8217;s dual-frequency precipitation radar is assessed.&lt;/p&gt;


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