The impact of revised simplified Arakawa–Schubert convection parameterization scheme in CFSv2 on the simulation of the Indian summer monsoon

Ganai, Malay K.; Mukhopadhyay, P.; Krishna, R. Phani Murali; Mahakur, M.

doi:10.1007/s00382-014-2320-4

Cited by 24 publications

(35 citation statements)

References 81 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Earlier studies [e.g., G14 ; Abhik et al ., ] have indicated that the convective processes are the major source of systematic biases in CFSv2. Some of these model biases, particularly the diurnal cycle, daily PDF and the seasonal mean precipitation, are found to be improved in the simulation of CFSv2 with the revised SAS convective scheme [ Ganai et al ., ]. In spite of these improvements, it still could not resolve the issue of a realistic ratio between convective and large‐scale rainfall over the global tropics.…”

Section: Discussionmentioning

confidence: 86%

“…This suggests that the simplified microphysics [ Zhao and Carr , ] in the model may not be sufficient to produce realistic large‐scale rainfall distribution and reduce the existing systematic biases of the model. To resolve these limitations of CFSv2, we have adopted similar revision of the existing convective parameterization (SAS) in the model as in Ganai et al ., []. Moreover, the Zhao‐Carr microphysical scheme of the model has been replaced by the WSM6 scheme in the CFSCR simulation.…”

Section: Discussionmentioning

confidence: 99%

“…Ganai et al . [] employed the revised SAS scheme for long simulations in CFS and showed that the performance of the model improves in simulating diurnal variability and mean climate during the boreal summer. However, the ratio between convective and large‐scale rainfall over global tropics did not show any improvement.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Revised cloud processes to improve the mean and intraseasonal variability of Indian summer monsoon in climate forecast system: Part 1

Abhik

Krishna

Mahakur

et al. 2017

J Adv Model Earth Syst

Self Cite

View full text Add to dashboard Cite

The National Centre for Environmental Prediction (NCEP) Climate Forecast System (CFS) is being used for operational monsoon prediction over the Indian region. Recent studies indicate that the moist convective process in CFS is one of the major sources of uncertainty in monsoon predictions. In this study, the existing simple cloud microphysics of CFS is replaced by the six‐class Weather Research Forecasting (WRF) single moment (WSM6) microphysical scheme. Additionally, a revised convective parameterization is employed to improve the performance of the model in simulating the boreal summer mean climate and intraseasonal variability over the Indian summer monsoon (ISM) region. The revised version of the model (CFSCR) exhibits a potential to improve shortcomings in the seasonal mean precipitation distribution relative to the standard CFS (CTRL), especially over the ISM region. Consistently, notable improvements are also evident in other observed ISM characteristics. These improvements are found to be associated with a better simulation of spatial and vertical distributions of cloud hydrometeors in CFSCR. A reasonable representation of the subgrid‐scale convective parameterization along with cloud hydrometeors helps to improve the convective and large‐scale precipitation distribution in the model. As a consequence, the simulated low‐frequency boreal summer intraseasonal oscillation (BSISO) exhibits realistic propagation and the observed northwest‐southeast rainband is well reproduced in CFSCR. Additionally, both the high and low‐frequency BSISOs are better captured in CFSCR. The improvement of low and high‐frequency BSISOs in CFSCR is shown to be related to a realistic phase relationship of clouds.

show abstract

Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Revised cloud processes to improve the mean and intraseasonal variability of Indian summer monsoon in climate forecast system: Part 1

Abhik

Krishna

Mahakur

et al. 2017

J Adv Model Earth Syst

Self Cite

View full text Add to dashboard Cite

show abstract

“…2 of Sperber et al 2013). 75The limited horizontal resolution of CGCMs is frequently listed as a major 76 caveat because current coarse atmospheric models cannot properly resolve orography 77 2013) or convection (Pattnaik et al 2013, Ganai et al 2015, which all significantly 80 contribute to the total ISM rainfall, especially in the monsoon trough region. 81…”

mentioning

confidence: 99%

Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean–atmosphere tropical-channel model

et al. 2016

View full text Add to dashboard Cite

precipitations are underestimated over India while they are overestimated over the 37 southwestern Indian Ocean, South-East Asia and the Maritime Continent. The ISM 38 onset is delayed by several weeks, an error which is also very common in current 39 CGCMs. 40We show that land surface temperature errors are a major source of the ISM 41 low-level circulation and rainfall biases in our model: a cold bias over the East (ME) region weakens the Findlater jet while a warm bias over India strengthens 43 the monsoon circulation over the southern Bay of Bengal. A surface radiative heat 44 budget analysis reveals that the cold bias is due to an overestimated albedo in this 45 desertic ME region. Two new simulations using a satellite-observed land albedo show 46 a significant and robust improvement in terms of ISM circulation and precipitation. 47Furthermore, the ISM onset is shifted back by one month and becomes in phase with 48 observations. Finally, a supplementary set of simulations at 0.25°-resolution confirms 49 the robustness of our results and shows an additional reduction of the warm and dry 50 bias over India. These findings highlight the strong sensitivity of the simulated ISM 51 rainfall and its onset timing to the surface land heating pattern and amplitude, 52 especially in the ME region. It also illustrates the key-role of land surface processes 53 and horizontal resolution for improving the ISM representation, and more generally 54 the monsoons, in current CGCMs. 55 56 57 Keywords 58Indian Summer Monsoon; land surface albedo; horizontal resolution; 59 precipitation biases; monsoon onset; CGCM 60 3 Introduction 61 62The Indian Summer Monsoon (ISM; see Table 1 for acronyms) brings 63 substantial rainfall from June to September to some of the world most populated 64 regions, whose economy relies mainly on agriculture and water resources. But despite 65 recent progress in our understanding of mechanisms driving ISM precipitation, 66Coupled General Circulation Models (CGCMs) are still not able to correctly represent 67 its main spatial and temporal characteristics (Sperber et al. 2013) and the skill of 68 seasonal ISM predictions by dynamical or statistical models remains currently very 69 low, contrary to what is observed in other tropical regions (Wang et al. 2015). 70While some improvements have been achieved with the last generation of 71CGCMs, especially in terms of intraseasonal variability (Abhik et al. 2014, Sabeerali 72 et al. 2013, some basic features of the ISM, such as the onset or 73 the rainfall spatial distribution, are still poorly captured with a persisting (wet) dry 74 bias over (ocean) land (see Fig. 2 of Sperber et al. 2013). 75The limited horizontal resolution of CGCMs is frequently listed as a major 76 caveat because current coarse atmospheric models cannot properly resolve orography 77 2013) or convection (Pattnaik et al. 2013, Ganai et al. 2015, which all significantly 80 contribute to the total ISM rainfall, especially in the monsoon trough region. 81Regional Climate Models (RCMs) al...

show abstract

“…However, the new physics package also increased the surface temperature bias and negative wind speed bias throughout the atmosphere. Ganai et al [2015] evaluated the performance of several combinations of shallow and deep convection in representing the Indian Summer Monsoon using the CFSv2. They verified that the best configuration for representing the monsoon is the use of the New SAS deep convection scheme without using the SAS-based shallow cumulus.…”

Section: Journal Of Advances In Modeling Earth Systems 101002/2016msmentioning

confidence: 99%

The heated condensation framework as a convective trigger in the NCEP Climate Forecast System version 2

Bombardi

Tawfik

Manganello

et al. 2016

J Adv Model Earth Syst

View full text Add to dashboard Cite

An updated version of the Heated Condensation Framework (HCF) is implemented as a convective triggering criterion into the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). The new trigger replaces the original criteria in both the deep (Simplified Arakawa‐Schubert – SAS) and shallow (SAS based) convective schemes. The performance of the original and new triggering criteria is first compared against radiosonde observations. Then, a series of hindcasts are performed to evaluate the influence of the triggering criterion in the CFSv2 representation of summer precipitation, the diurnal cycle of precipitation, and hurricanes that made landfall. The observational analysis shows that the HCF trigger better captures the frequency of convection, where the original SAS trigger initiates convection too often. When implemented in CFSv2, the HCF trigger improves the seasonal forecast of the Indian summer monsoon rainfall, including the representation of the onset dates of the rainy season over India. On the other hand, the HCF trigger increases error in the seasonal forecast of precipitation over the eastern United States. The HCF trigger also improves the representation of the intensity of hurricanes. Moreover, the simulation of hurricanes provides insights on the mechanism whereby the HCF trigger impacts the representation of convection.

show abstract

The impact of revised simplified Arakawa–Schubert convection parameterization scheme in CFSv2 on the simulation of the Indian summer monsoon

Cited by 24 publications

References 81 publications

Revised cloud processes to improve the mean and intraseasonal variability of Indian summer monsoon in climate forecast system: Part 1

Revised cloud processes to improve the mean and intraseasonal variability of Indian summer monsoon in climate forecast system: Part 1

Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean–atmosphere tropical-channel model

The heated condensation framework as a convective trigger in the NCEP Climate Forecast System version 2

Contact Info

Product

Resources

About