Soil Moisture and Climate Change - RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY

SOIL MOISTURE AND CLIMATE CHANGE

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

TERMINATED

Funding Source

HATCH

Reporting Frequency

Annual

Accession No.

0201271

Grant No.

(N/A)

Project No.

NJ07172

Proposal No.

(N/A)

Multistate No.

(N/A)

Program Code

(N/A)

Project Start Date

Sep 1, 2004

Project End Date

Aug 31, 2009

Grant Year

(N/A)

Project Director
Robock, A.

Recipient Organization
RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
3 RUTGERS PLZA
NEW BRUNSWICK,NJ 08901-8559

Performing Department
ENVIRONMENTAL SCIENCES

Non Technical Summary
Climate change will have significant impacts on the hydrology of New Jersey and the rest of the planet. We will use actual soil moisture observations and climate models to better understand the water cycle and how it will change with climate change.

Animal Health Component

(N/A)

Research Effort Categories

Basic

100%

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
132	0110	2070	20%
132	0210	2070	30%
132	0430	2070	50%

Knowledge Area
132 - Weather and Climate;

Subject Of Investigation
0210 - Water resources; 0110 - Soil; 0430 - Climate;

Field Of Science
2070 - Meteorology and climatology;

Goals / Objectives
Soil moisture is an important component of climate change. Among the many reasons, the most significant include the following. Soil moisture is responsible for partitioning outgoing convective fluxes between sensible and latent heat flux, with a strong effect on the resulting surface temperature. Soil moisture is the main source of natural water resources for agriculture and natural vegetation. Drought is a soil moisture deficiency. Plants depend on soil moisture. Unfavorable changes in the soil moisture regime, with summer drying, are predicted as a result of global greenhouse warming. Flooding is a soil moisture excess. Soil moisture affects not only the vertical fluxes of energy and moisture, but also the horizontal fluxes of moisture, namely runoff. Soil moisture variations from month to month are as large as the other main terms of the land surface water balance, namely precipitation, evaporation, and runoff. Correct monitoring of each of these variables is necessary to avoid the appearance of unpredicted anomalies in the hydrological cycle. Soil moisture, along with snow cover, is also the most important component of meteorological memory for the climate system over the land. Soil moisture anomalies are an important initial condition for seasonal forecasts. If soil moisture is an important component of the climate system, then soil moisture observations are important. Different scientists study soil moisture in various ways, including as an internal parameter of their models, a component of the water budget of the upper soil layer, a part of the water resources available for agricultural crops and natural vegetation, a physical carrier of meteorological memory, or an important problem of greenhouse global warming. Real in situ data, ground truth, is necessary for land surface model development and evaluation, for climatological analysis, and for calibration and evaluation of remote sensing observations. As climate and soil moisture change, there will be large impacts on many human activities, especially agriculture. The specific objectives of this work are: 1. Understand the spatial and temporal scales of soil moisture variations. 2. Improve the ability of climate models to simulate soil moisture variations. 3. Develop techniques for remote sensing of soil moisture. 4. Detect the anthropogenic signal in global climate change using soil moisture and other hydrological observations. 5. Develop scenarios of future climate change in New Jersey and use them in integrated assessment of the impact of global climate change on New Jersey, including impacts on agriculture.

Project Methods
It is the goal of this work to identify future changes of soil moisture, through data analysis, remote sensing, and modeling, and to identify the potential impacts in New Jersey. This work will combine my present work on soil moisture with work that I conduct with the Center for Environmental Prediction (CEP) and to integrated assessment with other researchers at Cook College. I will work with this output to identify the impacts of future climate change on agricultural and other activities in New Jersey. Specifically I will: 1. Collect soil moisture observations, enhancing the Global Soil Moisture Data Bank. The data collection will include ancillary meteorological, radiation, and flux data, which will be used to validate climate models simulations of the land surface in the same locations. 2. Land surface scheme intercomparisons. This will involve organizing international climate model intercomparison projects, forcing the models with observations of meteorology and radiation from various climate regimes, and validating the results with our soil moisture observations. We will expand our successful experiment with data from a grassland catchment at Valdai, Russia, for an 18-year period, to the catchment at Kamennaya Steppe and will organize other such experiments using data from other locations with other climates and vegetation. 3. Comparison of observed trends with simulations from transient global warming climate model simulations. While climate model simulations of doubled CO2 suggest summer drying of mid-latitude continents, our preliminary observations show that it has actually been getting wetter in Russia and Mongolia for the past several decades in the summer. By comparing actual observations with the results of the latest transient climate model simulations, we will see when the drying is actually expected to occur, and determine when to expect to see an anthropogenic signal in this part of the hydrological system. 4. Derivation of calibration of microwave satellite observations based on in situ soil moisture observations. The only way to actually observe soil moisture globally will be with remote sensing. We will use our extensive data collection to develop these techniques with microwave and other sensors. 5. Climate model experiments to develop high-resolution scenarios for New Jersey. The CEP conducts climate model experiments that focuses on detailed high-resolution simulations centered over New Jersey. We use nested-grid approaches iby using output from global climate models. One of the important outputs of this work will be detailed prediction of the impacts of global climate change on local hydrology. 6. Work with other Cook College scientists to apply scenarios to agricultural and other activities. We will identify the sensitivities of local agricultural and other activities to the projected local climate changes and then conduct integrated assessments of the potential impacts. These will be used to develop adaptation strategies to mitigate the potential impacts.

Progress 09/01/04 to 08/31/09

Outputs
OUTPUTS: Papers presented at conferences: Land surface model evaluation using a new soil moisture dataset from Kamennaya Steppe, Russia (with T. Atkins and N. Speranskaya; presented by T. Atkins; AGU Fall Meeting, San Francisco, California, December 13-17, 2004) Forty Five Years of Observed Soil Moisture in the Ukraine: No Summer Desiccation (Yet) (with M. Mu, K. Y. Vinnikov, I. V. Trofimova, and T. I. Adamenko; presented by G. Miguez-Macho; AGU Fall Meeting, San Francisco, California, December 13-17, 2004) Evaluation of Reanalysis Soil Moisture Simulations Using Newly Updated Soil Moisture Observations from the Ukraine and China (with H. Li, M. Mu, and K. Y. Vinnikov; 19th AMS Conference on Hydrology and 16th AMS Conference on Climate Variability and Change; San Diego, California, January 10-13, 2005) Non-uniform root distribution in a land surface model to improve soil moisture and surface flux simulations (with Thomas Atkins; presented by Thomas Atkins; 19th AMS Conference on Hydrology; San Diego, California, January 10-13, 2005) Evaluation of IPCC soil moisture simulations using observations for the second half of the 20th Century (with Haibin Li; presented by Haibin Li; International Workshop on IPCC Model Analysis, Honolulu, Hawaii, March 1-4, 2005) Evaluation of Reanalysis Soil Moisture Simulations Using Newly Updated Soil Moisture Observations from the Ukraine and China (invited presentation; with H. Li, M. Mu, and K. Y. Vinnikov; European Geosciences Union General Assembly, Vienna, Austria, April 24-29, 2005. Also served as session chair.) Evaluation of Soil Moisture Ocean Salinity satellite retrievals of soil moisture using in situ soil moisture observations (First Meeting of the SMOS Validation and Retrieval Team, Avila, Spain, November 21-24, 2005) Evaluation of IPCC AR4 Soil Moisture Simulations for the Second Half of the 20th Century (with H. Li and M. Wild; presented by H. Li; AGU Fall Meeting, San Francisco, California, December 5-9, 2005) The Global Soil Moisture Data Bank - Benchmark Soil Moisture Observations (with Haibin Li and Konstantin Y. Vinnikov; AGU Fall Meeting, San Francisco, California, December 5-9, 2005) A Strategy for a Global In-Situ Soil Moisture Network (with Peter J. van Oevelen, Tom J. Jackson, D Entekhabi, and Yann H. Kerr; presented by Peter J. van Oevelen; AGU Fall Meeting, San Francisco, California, December 5-9, 2005) Effects of solar dimming on soil moisture trends (with Haibin Li; presented by Haibin Li; 18th American Meteorological Society Conference on Climate Variations, Atlanta, Georgia, January 29 - February 2, 2006) Using soil moisture observations to study climate variations, to evaluate climate models, and as ground truth for remote sensing (Invited presentation: International Soil Moisture Working Group Workshop, Noordwijk, Netherlands, March 28-29, 2006) Effects of solar dimming on soil moisture trends (with H. Li; European Geosciences Union General Assembly, Vienna, Austria, April 3-7, 2006) And others that you have no room for. PARTICIPANTS: Haibin Li completed a Ph.D. at Rutgers working on this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
We determined that reanalyses and state of the art climate models do a poor job of simulating soil moisture, both in trends and mean values. In situ soil moisture observations are invaluable for evaluating remote sensing. The longest record of soil moisture that exists, 45 years of summer observations for the Ukraine, show an upward trend, in spite of global warming. We have shown that the trend is caused by solar dimming, that is the increased tropospheric pollution blocked out sunlight and reduced evaporation.

Publications

Li, Haibin, Alan Robock, Suxia Liu, Xingguo Mo, and Pedro Viterbo, 2005: Evaluation of reanalysis soil moisture simulations using updated Chinese soil moisture observations. J. Hydrometeorol., 6, 180-193.
Prigent, Catherine, Filipe Aires, William B. Rossow, and Alan Robock, 2005: Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale: Relationship of satellite observations to in situ soil moisture measurements,. J. Geophys. Res., 110, D07110, doi:10.1029/2004JD005087.
Robock, Alan, Mingquan Mu, Konstantin Vinnikov, Iryna V. Trofimova, and Tatyjana I. Adamenko, 2005: Forty five years of observed soil moisture in the Ukraine: No summer desiccation (yet). Geophys. Res. Lett., 32, L03401, doi:10.1029/2004GL021914.
Robock, Alan, and Haibin Li, 2006: Solar dimming and CO2 effects on soil moisture trends. Geophys. Res. Lett., 33, L20708, doi:10.1029/2006GL027585.
Li, Haibin, Alan Robock, and Martin Wild, 2007: Evaluation of Intergovernmental Panel on Climate Change Fourth Assessment soil moisture simulations for the second half of the twentieth century. J. Geophys. Res., 112, D06106, doi:10.1029/2006JD007455.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: None. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
None.

Publications

Anyah, Richard, Christopher P. Weaver, Gonzalo Miguez-Macho, Ying Fan, and Alan Robock, 2008: Incorporating water table dynamics in climate modeling: 3. Simulated groundwater influence on coupled land-atmosphere variability. J. Geophys. Res., 113, D07103, doi:10.1029/2007JD009087.

Progress 01/01/07 to 12/31/07

Outputs
Conducted research on soil moisture, land surface modeling, and regional climate modeling.

Impacts
Soil moisture trends, particularly during the growing season, are an important possible consequence of global warming. We compared soil moisture simulations from Intergovernmental Panel on Climate Change Fourth Assessment climate models forced with observed climate forcings for the past century, and evaluate them using in situ soil moisture measurements from over 140 stations or districts in mid-latitudes of the Northern Hemisphere. The models showed realistic seasonal cycles for Ukraine, Russia, and Illinois, but generally poor seasonal cycles for Mongolia and China. To explore the summer drying issue for the second half of the 20th century, we analyzed the linear trend of soil moisture for Ukraine and Russia. Observations from both regions show increases in summer for the period from 1958-1999 that were larger than most trends in the model simulations. Only two out of 25 model realizations show trends comparable to those of observations. These two trends, however, are due to internal model variability rather than a result of external forcing. Changes in precipitation and temperature cannot fully explain soil moisture increases for Ukraine and Russia, which indicates that other factors might have played a dominant role on the observed patterns for soil moisture. We suggest that changes in solar irradiance (the dimming effect) and resultant changes in evaporative demand explain most of the observed soil moisture trends. We examined the observed water table depth in the lower 48 states of the U.S. in search of salient spatial and temporal features that are relevant to climate dynamics. As a means to interpolate and synthesize the scattered observations, we use a simple two-dimensional groundwater flow model to construct an equilibrium water table as a result of long-term climatic and geologic forcing. Model simulations suggest that the water table depth exhibits spatial organization at watershed, regional and continental scales, which may have implications for the spatial organization of soil moisture at similar scales. The observations suggest that water table depth varies at diurnal, event, seasonal, and inter-annual scales, which may have implications for soil moisture memory at these scales. Where the water table is shallow, the groundwater reservoir is linked to the soil water reservoir through 2-way fluxes. At these locations, the role of the groundwater shifts from being primarily a sink to being primarily a source for the soil, as the season progresses from the wet spring to the dry autumn. Through the 2-way fluxes, groundwater exerts a certain degree of control on the root-zone soil moisture fields; there is an apparent spatial correlation between the distribution of shallow water table and wet soil. Since the water table reflects long-term climatic and topographic forcing and exhibits strong spatial organization, its link to the soil moisture gives the latter a certain degree of spatial organization as well. The slow changing nature of the water table acts to stabilize the temporal variations in soil water, giving the latter stronger seasonal persistence.

Publications

Li, Haibin, Alan Robock, and Martin Wild, 2007: Evaluation of Intergovernmental Panel on Climate Change Fourth Assessment soil moisture simulations for the second half of the twentieth century. J. Geophys. Res., 112, D06106, doi:10.1029/2006JD007455.
Fan, Ying, Gonzalo Miguez-Macho, Christopher Weaver, Robert Walko, and Alan Robock, 2007: Incorporating water table dynamics in climate modeling: 1. Water table observations and the equilibrium water table. J. Geophys. Res., 112, D10125, doi:10.1029/2006JD008111.
Miguez-Macho, Gonzalo, Ying Fan, Christopher Weaver, Robert Walko, and Alan Robock, 2007: Incorporating water table dynamics in climate modeling: 2. Formulation, validation, and soil moisture simulation. J. Geophys. Res., 112, D13108, doi:10.1029/ 2006JD008112.

Progress 01/01/06 to 12/31/06

Outputs
This paper incorporates the latest improvements in inter-satellite calibration, along with a new statistical technique, to determine the diurnal and seasonal cycles and climatic trends of 1978-2004 tropospheric temperature using Microwave Sounding Unit measurements. We also compare the latitudinal distribution of temperature trends from the surface and troposphere with each other and with model simulations for the past 26 years. The observations at the surface and in the troposphere are consistent with climate model simulations. At mid- and high latitudes in the Northern Hemisphere, the zonally averaged temperature at the surface increased faster than in the troposphere while at low latitudes of both hemispheres the temperature increased more slowly at the surface than in the troposphere. The resulting global averaged tropospheric trend is +0.20 K/10 yr, with a standard error of 0.05 K/10 yr, which compares very well with the trend obtained from surface reports. It is commonly believed that greenhouse-gas-induced global warming can weaken the East Asian winter monsoon but strengthen the summer monsoon, due to stronger warming over high-latitude land as compared to low-latitude oceans. However, in this study we show that the surface wind speed associated with the East Asian monsoon has significantly weakened in both winter and summer in the recent three decades. From 1969 to 2000, annual mean wind speed over China has decreased steadily by 28% and the prevalence of windy days (daily mean wind speed > 5 m/s) has decreased by 58%. The temperature trends during this period have not been uniform. Significant winter warming in northern China may explain the decline of the winter monsoon, while the summer cooling in Central South China and warming over the South China Sea and the Western North Pacific Ocean may be responsible for weakening the summer monsoon. In addition, we found that the monsoon wind speed is also highly correlated with surface solar radiation. The present results, when interpreted together with those of recent climate model simulations, suggest that the decline of the EA winter monsoon may be related to global-scale greenhouse-gas-induced warming, while the decline of the EA summer monsoon may be related to local air-pollution-induced cooling over South-Central China. Summer soil moisture increased significantly from 1958 to the mid 1990s in Ukraine and Russia. This trend cannot be explained by changes in precipitation and temperature alone. To investigate the possible contribution from solar dimming and upward CO2 trends, we conducted experiments with a sophisticated land surface model. We demonstrate, by imposing a downward trend in incoming shortwave radiation forcing to mimic the observed dimming, that the observed soil moisture pattern can be well reproduced. On the other hand, the effects of upward CO2 trends were relatively small for the study period. Our results suggest tropospheric air pollution plays an important role in land water storage at the regional scale, and needs to be addressed accurately to study the effects of global warming on water resources.

Impacts
We are making progress in developing a system for evaluating the effect of climate change on soil moisture and water resources for New Jersey.

Publications

Vinnikov, Konstantin Y., Norman C. Grody, Alan Robock, Ronald J. Stouffer, Philip D. Jones, and Mitchell D. Goldberg, 2006: Temperature trends at the surface and in the troposphere. J. Geophys. Res., 111, D03106, doi:10.1029/2005JD006392.
Xu, Ming, Chih-Pei Chang, Congbin Fu, Ye Qi, Alan Robock, David Robinson, and Huai-min Zhang, 2006: Steady decline of east Asian monsoon winds, 1969-2000: Evidence from direct ground measurements of wind speed. J. Geophys. Res., 111, D24111, doi: 10.1029/2006JD007337.
Robock, Alan, and Haibin Li, 2006: Solar dimming and CO2 effects on soil moisture trends. Geophys. Res. Lett., 33, L20708, doi:10.1029/2006GL027585.

Progress 01/01/05 to 12/31/05

Outputs
We investigated the reasons for biases in regional climate simulations, trying to discern whether they arise from deficiencies in the model parameterizations or are due to dynamical problems. Using the Regional Atmospheric Modeling System (RAMS) forced by the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, we simulated the detailed climate over North America at 50 km resolution for June 2000. We were only able to correct the precipitation location biases by implementing spectral nudging of the large scale (wavelength 2500 km) dynamics in RAMS. This corrected for circulation errors produced by interactions and reflection of the internal domain dynamics with the lateral boundaries where the model was forced by the reanalysis. We present the longest data set of observed soil moisture available in the world, 45 yr of gravimetrically-observed plant available soil moisture for the top 1 m of soil, observed every 10 days for April-October for 141 stations from fields with either winter or spring cereals from the Ukraine for 1958-2002. The observations show a positive soil moisture trend for the entire period of observation, with the trend leveling off in the last two decades. Although models of global warming predict summer desiccation in a greenhouse-warmed world, there is no evidence for this in the observations yet, even though the region has been warming for the entire period. Climate model simulations for the period show the same general shape as the observations, but differ quite a bit from each other and from the observations. An observed downward trend in insolation may have produced a downward trend in evaporation and may have contributed to the upward soil moisture trend. Using 19 years of Chinese soil moisture data from 1981-1999, we evaluated soil moisture in three reanalysis outputs: ERA40, NCEP/NCAR reanalysis (R-1), and NCEP/DOE reanalysis 2 (R-2) over China. This new long time series of observed soil moisture will prove valuable for other studies of climate change, remote sensing, and model evaluation. We conducted a systematic and integrated analysis of the sensitivity of the available satellite observations to in situ soil moisture measurements. The satellite observations include passive microwave emissivities, active microwave scatterometer data, and infrared estimates of the diurnal amplitude of the surface skin temperature. The Global Soil Moisture Data Bank provides in situ soil moisture measurements in five separate regions. This simultaneous analysis of various satellite observations and the large amount of in situ measurements has two major advantages. We helped to identify and separate the physical mechanisms that affect the satellite observations. We also conducted an objective comparison of the relative potential of the various satellite observations for soil moisture retrieval when other conditions are held constant.

Impacts
We are making progress in developing a system for evaluating the effect of climate change on soil moisture and water resources for New Jersey.

Publications

Miguez-Macho, Gonzalo, Georgiy L. Stenchikov, and Alan Robock, 2005: Regional climate simulations over North America: Interaction of local processes with improved large-scale flow. J. Climate, 18, 1227-1246.
Prigent, Catherine, Filipe Aires, William B. Rossow, and Alan Robock, 2005: Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale: Relationship of satellite observations to in situ soil moisture measurements. J. Geophys. Res., 110, D07110, doi:10.1029/2004JD005087.
Li, Haibin, Alan Robock, Suxia Liu, Xingguo Mo, and Pedro Viterbo, 2005: Evaluation of reanalysis soil moisture simulations using updated Chinese soil moisture observations. J. Hydrometeorol., 6, 180-193.
Robock, Alan, Mingquan Mu, Konstantin Vinnikov, Iryna V. Trofimova, and Tatyjana I. Adamenko, 2005: Forty five years of observed soil moisture in the Ukraine: No summer desiccation (yet). Geophys. Res. Lett., 32, L03401, doi:10.1029/2004GL021914.

Progress 01/01/04 to 12/31/04

Outputs
It is too early to report on this project.

Impacts
It is too early to report on this project.

Publications

No publications reported this period