scholarly journals NARR’s Atmospheric Water Cycle Components. Part II: Summertime Mean and Diurnal Interactions

2010 ◽  
Vol 11 (6) ◽  
pp. 1220-1233 ◽  
Author(s):  
Alex C. Ruane
Keyword(s):  
Diurnal Cycle ◽  
North American ◽  
Water Cycle ◽  
Value Added ◽  
Precipitable Water ◽  
Strong Relationship ◽  
Moisture Flux ◽  
Atmospheric Water ◽  
Annual Variations ◽  
Model Precipitation

Abstract Summertime interactions in the North American Regional Reanalysis (NARR) atmospheric water cycle are examined from a user’s perspective over the 1980–99 period with a particular emphasis on the diurnal cycle, the nocturnal maximum of precipitation over the Midwest, and the impacts of precipitation assimilation. NARR’s full-year mean atmospheric water cycle and its annual variations are examined in Part I of this study. North American summertime (June–August) features substantial convective activity that is often organized on a diurnal scale, although diverse regional diurnal features are evident to various extents in high-resolution precipitation products. NARR’s hourly assimilation of precipitation observations over the continental United States allows it to resolve diurnal effects on the water cycle, but in other regions the diurnal cycle of precipitation is imposed from an external reanalysis model. The prominent nocturnal maximum in precipitation across the upper Midwest is captured in NARR, but different precipitation assimilation sources disrupt the propagation of convective systems across the Canadian border. Normalized covariances of NARR’s diurnal water cycle component interactions in the nocturnal maximum region reveal a strong relationship between moisture convergence and precipitation, and also measure the way in which the precipitable water column holds a lagged response between evaporation and precipitation. In many regions the diurnal cycle of rainfall is driven by interactions with water cycle components that differ from those driving the seasonal cycle. A comparison between NARR’s precipitation and an estimate of the model precipitation prior to precipitation assimilation distinguishes the portion of the water cycle captured in full by the model and that which is value added by the assimilation routine. The nocturnal rainfall maximum is not present in the model precipitation estimate, leading to diurnal-scale biases in the evaporation and moisture flux convergence fields that are not directly modified by precipitation assimilation.

scholarly journals NARR’s Atmospheric Water Cycle Components. Part I: 20-Year Mean and Annual Interactions

2010 ◽  
Vol 11 (6) ◽  
pp. 1205-1219 ◽  
Author(s):  
Alex C. Ruane
Keyword(s):  
High Resolution ◽  
Water Cycle ◽  
Moisture Flux ◽  
Climate Impact ◽  
Atmospheric Water ◽  
Moisture Flux Convergence ◽  
The North ◽  
Precipitation Estimates ◽  
Assimilation Scheme ◽  
Model Precipitation

Abstract The North American Regional Reanalysis (NARR) atmospheric water cycle is examined from 1980 to 1999 using a budget approach, with a particular emphasis on annual component interactions and the role of hourly precipitation assimilation. NARR’s summertime atmospheric water cycle and diurnal component interactions are examined in Part II of this study. NARR’s high-resolution reanalysis and precipitation assimilation allow an improved climatology of mean water cycle components over North America, which is very attractive for applications, climate impact assessments, and as a basis for comparison with other products. A 20-yr climatology of precipitation, evaporation, moisture flux convergence, and the residual error term are produced for comparison to observations, other reanalyses and models, and future climate scenarios. Maps of the normalized covariance of annual precipitation with each of the other water cycle components identify regimes of seasonal interaction that form an additional basis for comparison. The annual cycle of assimilated precipitation is compared to high-resolution precipitation products as an example, and points of interest for continuing studies are identified. Analysis of the mean and transient balances reveals a significant effect from NARR’s precipitation assimilation scheme, which is investigated using an estimate of NARR’s underlying model precipitation (before assimilation), generated using the precipitation assimilation increment as a proxy. Biases of the precipitation assimilation scheme are then characterized spatially and temporally to inform the interpretation of NARR applications and comparisons. These model precipitation estimates reveal a more tightly closed atmospheric water cycle with predominantly excessive precipitation, resulting in too vigorous evaporation and moisture flux convergences. The sign and magnitude of evaporation and moisture flux convergence biases are found to be related to the precipitation assimilation correction and are important to consider in applications of NARR output.

scholarly journals The North American Monsoon GPS Transect Experiment 2013

2016 ◽  
Vol 97 (11) ◽  
pp. 2103-2115 ◽  
Author(s):  
Yolande L. Serra ◽  
David K. Adams ◽  
Carlos Minjarez-Sosa ◽  
James M. Moker ◽  
Avelino F. Arellano ◽  
...  
Keyword(s):  
Water Vapor ◽  
North American ◽  
Water Cycle ◽  
Precipitable Water ◽  
Annual Rainfall ◽  
North American Monsoon ◽  
Atmospheric Sciences ◽  
The North ◽  
Northwestern Mexico ◽  
The Impact

Abstract Northwestern Mexico experiences large variations in water vapor on seasonal time scales in association with the North American monsoon, as well as during the monsoon associated with upper-tropospheric troughs, mesoscale convective systems, tropical easterly waves, and tropical cyclones. Together these events provide more than half of the annual rainfall to the region. A sufficient density of meteorological observations is required to properly observe, understand, and forecast the important processes contributing to the development of organized convection over northwestern Mexico. The stability of observations over long time periods is also of interest to monitor seasonal and longer-time-scale variability in the water cycle. For more than a decade, the U.S. Global Positioning System (GPS) has been used to obtain tropospheric precipitable water vapor (PWV) for applications in the atmospheric sciences. There is particular interest in establishing these systems where conventional operational meteorological networks are not possible due to the lack of financial or human resources to support the network. Here, we provide an overview of the North American Monsoon GPS Transect Experiment 2013 in northwestern Mexico for the study of mesoscale processes and the impact of PWV observations on high-resolution model forecasts of organized convective events during the 2013 monsoon. Some highlights are presented, as well as a look forward at GPS networks with surface meteorology (GPS-Met) planned for the region that will be capable of capturing a wider range of water vapor variability in both space and time across Mexico and into the southwestern United States.

Influence of mid-latitude oceanic fronts on the atmospheric water cycle

2020 ◽  
Author(s):  
Fumiaki Ogawa ◽  
Thomas Spengler
Keyword(s):  
Heat Exchange ◽  
Large Scale ◽  
Water Cycle ◽  
Moisture Flux ◽  
Convective Precipitation ◽  
Atmospheric Water ◽  
Moisture Flux Convergence ◽  
Sst Front ◽  
Oceanic Fronts ◽  
Sst Fronts

<p>      Midlatitude oceanic fronts play an important role in the air-sea coupled weather and climate system. Created by the confluence of warm and cool oceanic western boundary currents, the strong sea-surface temperature (SST) gradient is maintained throughout the year. The climatological mean turbulent air-sea heat exchange maximizes along these SST fronts and collocates with the major atmospheric storm tracks. A recent study identified that the air-sea heat exchange along the SST front mainly occurs on sub-weekly time scales, associated with synoptic atmospheric disturbances. This implies a crucial role of air-sea moisture exchange along the SST fronts on the atmospheric water cycle through the intensification of atmospheric cyclones and the associated precipitation.  </p><p>      In this study, we investigate this influence of the SST front on the atmospheric water cycle by analyzing the atmospheric response to different prescribed SST in the Atmospheric general circulation model For the Earth Simulator (AFES). Changing the latitude of the prescribed zonally symmetric SST in aqua-planet configuration, we find a distinctive response in convective and large-scale precipitation, surface latent and sensible heat fluxes, as well as diabatic heating and moistening with respect to the latitude of SST front. Upward surface latent heat flux and convective precipitation always maximize along the equatorward flank of SST front. On the other hand, large-scale precipitation is always located on the poleward flank of the SST front, in correspondence with the maximum atmospheric moisture flux convergence. The moisture flux convergence is mainly associated with midlatitude eddies and not with the time mean transport. This highlights the influence of mid-latitude SST fronts on the atmospheric water cycle through the organization of atmospheric storm track.</p>

scholarly journals Evaluating Forecast Skills of Moisture from Convective-Permitting WRF-ARW Model during 2017 North American Monsoon Season

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 694 ◽  
Author(s):  
Christoforus Bayu Risanto ◽  
Christopher L. Castro ◽  
James M. Moker ◽  
Avelino F. Arellano ◽  
David K. Adams ◽  
...  
Keyword(s):  
North American ◽  
Monsoon Season ◽  
Precipitable Water ◽  
Weather Forecast ◽  
Moisture Flux ◽  
Rain Gauge ◽  
North American Monsoon ◽  
Convective Systems ◽  
The North ◽  
Northwestern Mexico

This paper examines the ability of the Weather Research and Forecasting model forecast to simulate moisture and precipitation during the North American Monsoon GPS Hydrometeorological Network field campaign that took place in 2017. A convective-permitting model configuration performs daily weather forecast simulations for northwestern Mexico and southwestern United States. Model precipitable water vapor (PWV) exhibits wet biases greater than 0.5 mm at the initial forecast hour, and its diurnal cycle is out of phase with time, compared to observations. As a result, the model initiates and terminates precipitation earlier than the satellite and rain gauge measurements, underestimates the westward propagation of the convective systems, and exhibits relatively low forecast skills on the days where strong synoptic-scale forcing features are absent. Sensitivity analysis shows that model PWV in the domain is sensitive to changes in initial PWV at coastal sites, whereas the model precipitation and moisture flux convergence (QCONV) are sensitive to changes in initial PWV at the mountainous sites. Improving the initial physical states, such as PWV, potentially increases the forecast skills.

scholarly journals The Diurnal Cycle of Precipitation over the North American Monsoon Region during the NAME 2004 Field Campaign

2008 ◽  
Vol 21 (4) ◽  
pp. 771-787 ◽  
Author(s):  
Emily J. Becker ◽  
Ernesto Hugo Berbery
Keyword(s):  
Diurnal Cycle ◽  
North American ◽  
Gulf Of California ◽  
Warm Season ◽  
Moisture Flux ◽  
North American Monsoon ◽  
The Core ◽  
The North ◽  
Eta Model ◽  
Diurnal Cycle Of Precipitation

Abstract The structure of the diurnal cycle of warm-season precipitation and its associated fields during the North American monsoon are examined for the core monsoon region and for the southwestern United States, using a diverse set of observations, analyses, and forecasts from the North American Monsoon Experiment field campaign of 2004. Included are rain gauge and satellite estimates of precipitation, Eta Model forecasts, and the North American Regional Reanalysis (NARR). Daily rain rates are of about the same magnitude in all datasets with the exception of the Climate Prediction Center (CPC) Morphing (CMORPH) technique, which exhibits markedly higher precipitation values. The diurnal cycle of precipitation within the core region occurs earlier in the day at higher topographic elevations, evolving with a westward shift of the maximum. This shift appears in the observations, reanalysis, and, while less pronounced, in the model forecasts. Examination of some of the fields associated with this cycle, including convective available potential energy (CAPE), convective inhibition (CIN), and moisture flux convergence (MFC), reveals that the westward shift appears in all of them, but more prominently in the latter. In general, warm-season precipitation in southern Arizona and parts of New Mexico shows a strong effect due to northward moisture surges from the Gulf of California. A reported positive bias in the NARR northward winds over the Gulf of California limits their use with confidence for studies of the moist surges along the Gulf; thus, the analysis is complemented with operational analysis and the Eta Model short-term simulations. The nonsurge diurnal cycle of precipitation lags the CAPE maximum by 6 h and is simultaneous with a minimum of CIN, while the moisture flux remains divergent throughout the day. During surges, CAPE and CIN have modifications only to the amplitude of their cycles, but the moisture flux becomes strongly convergent about 6 h before the precipitation maximum, suggesting a stronger role in the development of precipitation.

Investigation of the Summer Climate of the Contiguous United States and Mexico Using the Regional Atmospheric Modeling System (RAMS). Part I: Model Climatology (1950–2002)

2007 ◽  
Vol 20 (15) ◽  
pp. 3844-3865 ◽  
Author(s):  
Christopher L. Castro ◽  
Roger A. Pielke ◽  
Jimmy O. Adegoke
Keyword(s):  
United States ◽  
Diurnal Cycle ◽  
North American ◽  
Value Added ◽  
Atmospheric Modeling ◽  
Surface Energy Budget ◽  
Regional Atmospheric Modeling System ◽  
Convective Rainfall ◽  
Summer Climate ◽  
Regional Atmospheric Modeling

Abstract Fifty-three years of the NCEP–NCAR Reanalysis I are dynamically downscaled using the Regional Atmospheric Modeling System (RAMS) to generate a regional climate model (RCM) climatology of the contiguous United States and Mexico. Data from the RAMS simulations are compared to the recently released North American Regional Reanalysis (NARR), as well as observed precipitation and temperature data. The RAMS simulations show the value added by using a RCM in a process study framework to represent North American summer climate beyond the driving global atmospheric reanalysis. Because of its enhanced representation of the land surface topography, the diurnal cycle of convective rainfall is present. This diurnal cycle largely governs the transitions associated with the evolution of the North American monsoon with regards to rainfall, the surface energy budget, and surface temperature. The lower frequency modes of convective rainfall, though weaker, account for rainfall variability at a remote distance from elevated terrain. As in previous studies with other RCMs, RAMS precipitation is overestimated compared to observations. The Great Plains low-level jet (LLJ) is also well represented in both RAMS and NARR, but the Baja LLJ and associated gulf surges are not.

Analysis of the Atmospheric Water Cycle for the Laurentian Great Lakes Region using CMIP6 models

2021 ◽  
pp. 1-47
Author(s):  
Samar Minallah ◽  
Allison L. Steiner
Keyword(s):  
Great Lakes ◽  
Seasonal Cycle ◽  
Water Cycle ◽  
Coupled Model ◽  
Moisture Flux ◽  
Laurentian Great Lakes ◽  
Convective Precipitation ◽  
Great Lakes Region ◽  
Total Precipitation ◽  
Atmospheric Water

AbstractThis study evaluates the historical climatology and future changes of the atmospheric water cycle for the Laurentian Great Lakes region using 15 Coupled Model Intercomparison Project Phase 6 (CMIP6) models. While the models have unique seasonal characteristics in the historical (1981 – 2010) simulations, common patterns emerge by the mid-century SSP2-4.5 scenario (2041 – 2070), including a prevalent shift in the precipitation seasonal cycle with summer drying and wetter winter-spring months, and a ubiquitous increase in the magnitudes of convective precipitation, evapotranspiration, and moisture inflow into the region. The seasonal cycle of moisture flux convergence is amplified (i.e., the magnitude of winter convergence and summer divergence increases), which is the primary driver of future total precipitation changes. Precipitation recycling ratio is also projected to decline in summer and increase in winter by the mid-century, signifying a larger contribution of the regional moisture (via evapotranspiration) to total precipitation in the colder months. Many models (6/15) do not include representation of the Great Lakes, while others (4/15) have major inconsistencies in how the lakes are simulated both in terms of spatial representation and treatment of lake processes. In models with some lake presence, contribution of lake grid cells to the regional evapotranspiration magnitude can be more than 50% in winter. In future, winter months have a larger increase in evaporation over water surfaces than the surrounding land, which corroborates past findings of sensitivity of deep lakes to climate warming and highlights the importance of lake representation in these models for reliable regional hydroclimatic assessments.

Dominant Balances and Exchanges of the Atmospheric Water Cycle in the Reanalysis 2 at Diurnal, Annual, and Intraseasonal Time Scales

2008 ◽  
Vol 21 (16) ◽  
pp. 3951-3966 ◽  
Author(s):  
Alex C. Ruane ◽  
John O. Roads
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Water Cycle ◽  
Precipitable Water ◽  
Temporal Variations ◽  
Department Of Energy ◽  
Atmospheric Water ◽  
Vapor Flux ◽  
Temporal Variance ◽  
Environmental Prediction

Abstract Output from the National Centers for Environmental Prediction–Department of Energy (NCEP–DOE) Reanalysis 2 (R2) is passed through a broadband filter to determine the normalized covariances that describe the variance of the atmospheric water cycle at diurnal, annual, and intraseasonal (∼7–80 days) time scales. Vapor flux convergence is residually defined to close the water cycle between successive 3-hourly output times from 2002 to 2004, resulting in a balance between precipitation, evaporation, precipitable water tendency, and vertically integrated vapor flux convergence. The same balance holds at each time scale, allowing 100% of each variable’s temporal variance to be described by its covariance with other water cycle components in the same variance category. Global maps of these normalized covariances are presented to demonstrate the unique balances and exchanges that govern temporal variations in the water cycle. The diurnal water cycle is found to be dominated by a land–sea contrast, with continents controlled thermodynamically through evaporation and the oceans following dynamic convergence. The annual time-scale features significant meridional structure, with the low latitudes described mostly through variability in convergence and the extratropics governed by the properties of advected continental and maritime air masses. Intraseasonal transients lack direct solar oscillations at the top of the atmosphere and are characterized by propagating dynamic systems that act to adjust the precipitable water content of unsaturated regions or exchange directly with precipitation in saturated areas. By substituting the modeled precipitation with observation-based fields, a detailed description of the water cycle’s exchanges relating to the nocturnal precipitation maximum over the Midwest is obtained.

The Impact of Assimilating GPS Precipitable Water Vapor in Convective-Permitting WRF-ARW on North American Monsoon Precipitation Forecasts over Northwest Mexico

2021 ◽  
Author(s):  
Christoforus Bayu Risanto ◽  
Christopher L. Castro ◽  
Avelino F. Arellano ◽  
James M. Moker ◽  
David K. Adams
Keyword(s):  
Water Vapor ◽  
Data Assimilation ◽  
North American ◽  
Precipitable Water ◽  
Precipitable Water Vapor ◽  
North American Monsoon ◽  
Convective Systems ◽  
Northwest Mexico ◽  
Dewpoint Temperature ◽  
The Impact

AbstractWe assess the impact of GPS precipitable water vapor (GPS-PWV) data assimilation (DA) on short-range North American monsoon (NAM) precipitation forecasts, across 38 days with weak synoptic forcing, during the NAM GPS Hydrometeorological Network field campaign in 2017 over northwest Mexico. Utilizing an ensemble-based data assimilation technique, the GPS-PWV data retrieved from 18 observation sites are assimilated every hour for 12 hours into a 30-member ensemble convective-permitting (2.5 km) Advanced Research version of the Weather Research and Forecasting (WRF-ARW) model. As the assimilation of the GPS-PWV improves the initial condition of WRF by reducing the root mean square error and bias of PWV across 1200-1800 UTC, this also leads to an improvement in capturing nocturnal convection of mesoscale convective systems (MCSs; after 0300 UTC) and to an increase by 0.1 mm h-1 in subsequent precipitation during the 0300-0600 UTC period relative to no assimilation of the GPS-PWV (NODA) over the area with relatively more observation sites. This response is consistent with observed precipitation from the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement Final Precipitation product. Moreover, compared to the NODA, we find that the GPS-PWV DA decreases cloud top temperature, increases most unstable convective available energy and surface dewpoint temperature, and thus creates a more favorable condition for convective organization in the region.

scholarly journals The Atmospheric Water Balance over the Semiarid Murray–Darling River Basin

2008 ◽  
Vol 9 (3) ◽  
pp. 521-534 ◽  
Author(s):  
Clara Draper ◽  
Graham Mills
Keyword(s):  
Surface Water ◽  
Water Balance ◽  
River Basin ◽  
Moisture Flux ◽  
Limited Area ◽  
Consecutive Series ◽  
Atmospheric Water ◽  
Flux Divergence ◽  
Murray Darling Basin ◽  
Moisture Flux Divergence

Abstract The atmospheric water balance over the semiarid Murray–Darling River basin in southeast Australia is analyzed based on a consecutive series of 3- to 24-h NWP forecasts from the Australian Bureau of Meteorology’s Limited Area Prediction System (LAPS). Investigation of the LAPS atmospheric water balance, including comparison of the forecast precipitation to analyzed rain gauge observations, indicates that the LAPS forecasts capture the general qualitative features of the water balance. The key features of the atmospheric water balance over the Murray–Darling Basin are small atmospheric moisture flux divergence (at daily to annual time scales) and extended periods during which the atmospheric water balance terms are largely inactive, with the exception of evaporation, which is consistent and very large in summer. These features present unique challenges for NWP modeling. For example, the small moisture fluxes in the basin can easily be obscured by the systematic errors inherent in all NWP models. For the LAPS model forecasts, there is an unrealistically large evaporation excess over precipitation (associated with a positive bias in evaporation) and unexpected behavior in the moisture flux divergence. Two global reanalysis products (the NCEP Reanalysis I and the 40-yr ECMWF Re-Analysis) also both describe (physically unrealistic) long-term negative surface water budgets over the Murray–Darling Basin, suggesting that the surface water budget cannot be sensibly diagnosed based on output from current NWP models. Despite this shortcoming, numerical models are in general the most appropriate tool for examining the atmospheric water balance over the Murray–Darling Basin, as the atmospheric sounding network in Australia has extremely low coverage.

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