Details:

Journal Title:
Journal of Climate
Personal Author:
Halder, Subhadeep ; Dirmeyer, Paul A.
Halder, Subhadeep ; Dirmeyer, Paul A. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office)
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office) Less -
Description:
This observationally based study demonstrates the importance of the delayed hydrological response of snow cover and snowmelt over the Eurasian region and Tibet for variability of Indian summer monsoon rainfall during the first two months after onset. Using snow cover fraction and snow water equivalent data during 1967–2003, it is demonstrated that, although the snow-albedo effect is prevalent over western Eurasia, the delayed hydrological effect is strong and persistent over the eastern part. Long soil moisture memory and strong sensitivity of surface fluxes to soil moisture variations over eastern Asia and Tibet provide a mechanism for soil moisture anomalies generated by anomalies in winter and spring snowfall to affect rainfall during the initial months in summer. Dry soil moisture anomalies over the eastern Eurasian region associated with anomalous heating at the surface and midtroposphere help in anchoring of an anomalous upper-tropospheric “blocking” ridge around 100°E and its persistence. This not only leads to prolonged weakening of the subtropical westerly jet but also shifts its position southward of 30°N, followed by penetration of anomalous troughs in the westerlies into the Indian region. Simultaneously, intrusion of cold and dry air from the midlatitudes can reduce the convective instability and hence rainfall over India after the onset. Such a southward shift of the jet can also significantly weaken the vertical easterly wind shear over the Indian region in summer and lead to decrease in rainfall. This delayed hydrological effect also has the potential to modulate the snow–atmosphere coupling strength for temperature and precipitation in operational forecast models through soil moisture–evaporation–precipitation feedbacks.
Keywords:
[+]
Atmosphere Monsoons Runoff Soil Moisture Surface fluxes
Source:
Journal of Climate, 30(4), 1273-1289
DOI:
https://doi.org/10.1175/JCLI-D-16-0033.1
Document Type:
Journal Article
Funding:
Grant no. NA09OAR4310058 ; Grant no. NA14OAR4310160
Grant no. NA09OAR4310058 ; Grant no. NA14OAR4310160 Less -
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:003358a76e7dbebcfaa43cf4768402bafa9d83c8982fb4dab67a8289ba8993f8
Download URL:
https://repository.library.noaa.gov/view/noaa/28357/noaa_28357_DS1.pdf
File Type:

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